0,0 → 1,5061 |
/* |
This is a version (aka dlmalloc) of malloc/free/realloc written by |
Doug Lea and released to the public domain, as explained at |
http://creativecommons.org/licenses/publicdomain. Send questions, |
comments, complaints, performance data, etc to dl@cs.oswego.edu |
|
* Version 2.8.3 Thu Sep 22 11:16:15 2005 Doug Lea (dl at gee) |
|
Note: There may be an updated version of this malloc obtainable at |
ftp://gee.cs.oswego.edu/pub/misc/malloc.c |
Check before installing! |
|
* Quickstart |
|
This library is all in one file to simplify the most common usage: |
ftp it, compile it (-O3), and link it into another program. All of |
the compile-time options default to reasonable values for use on |
most platforms. You might later want to step through various |
compile-time and dynamic tuning options. |
|
For convenience, an include file for code using this malloc is at: |
ftp://gee.cs.oswego.edu/pub/misc/malloc-2.8.3.h |
You don't really need this .h file unless you call functions not |
defined in your system include files. The .h file contains only the |
excerpts from this file needed for using this malloc on ANSI C/C++ |
systems, so long as you haven't changed compile-time options about |
naming and tuning parameters. If you do, then you can create your |
own malloc.h that does include all settings by cutting at the point |
indicated below. Note that you may already by default be using a C |
library containing a malloc that is based on some version of this |
malloc (for example in linux). You might still want to use the one |
in this file to customize settings or to avoid overheads associated |
with library versions. |
|
* Vital statistics: |
|
Supported pointer/size_t representation: 4 or 8 bytes |
size_t MUST be an unsigned type of the same width as |
pointers. (If you are using an ancient system that declares |
size_t as a signed type, or need it to be a different width |
than pointers, you can use a previous release of this malloc |
(e.g. 2.7.2) supporting these.) |
|
Alignment: 8 bytes (default) |
This suffices for nearly all current machines and C compilers. |
However, you can define MALLOC_ALIGNMENT to be wider than this |
if necessary (up to 128bytes), at the expense of using more space. |
|
Minimum overhead per allocated chunk: 4 or 8 bytes (if 4byte sizes) |
8 or 16 bytes (if 8byte sizes) |
Each malloced chunk has a hidden word of overhead holding size |
and status information, and additional cross-check word |
if FOOTERS is defined. |
|
Minimum allocated size: 4-byte ptrs: 16 bytes (including overhead) |
8-byte ptrs: 32 bytes (including overhead) |
|
Even a request for zero bytes (i.e., malloc(0)) returns a |
pointer to something of the minimum allocatable size. |
The maximum overhead wastage (i.e., number of extra bytes |
allocated than were requested in malloc) is less than or equal |
to the minimum size, except for requests >= mmap_threshold that |
are serviced via mmap(), where the worst case wastage is about |
32 bytes plus the remainder from a system page (the minimal |
mmap unit); typically 4096 or 8192 bytes. |
|
Security: static-safe; optionally more or less |
The "security" of malloc refers to the ability of malicious |
code to accentuate the effects of errors (for example, freeing |
space that is not currently malloc'ed or overwriting past the |
ends of chunks) in code that calls malloc. This malloc |
guarantees not to modify any memory locations below the base of |
heap, i.e., static variables, even in the presence of usage |
errors. The routines additionally detect most improper frees |
and reallocs. All this holds as long as the static bookkeeping |
for malloc itself is not corrupted by some other means. This |
is only one aspect of security -- these checks do not, and |
cannot, detect all possible programming errors. |
|
If FOOTERS is defined nonzero, then each allocated chunk |
carries an additional check word to verify that it was malloced |
from its space. These check words are the same within each |
execution of a program using malloc, but differ across |
executions, so externally crafted fake chunks cannot be |
freed. This improves security by rejecting frees/reallocs that |
could corrupt heap memory, in addition to the checks preventing |
writes to statics that are always on. This may further improve |
security at the expense of time and space overhead. (Note that |
FOOTERS may also be worth using with MSPACES.) |
|
By default detected errors cause the program to abort (calling |
"abort()"). You can override this to instead proceed past |
errors by defining PROCEED_ON_ERROR. In this case, a bad free |
has no effect, and a malloc that encounters a bad address |
caused by user overwrites will ignore the bad address by |
dropping pointers and indices to all known memory. This may |
be appropriate for programs that should continue if at all |
possible in the face of programming errors, although they may |
run out of memory because dropped memory is never reclaimed. |
|
If you don't like either of these options, you can define |
CORRUPTION_ERROR_ACTION and USAGE_ERROR_ACTION to do anything |
else. And if if you are sure that your program using malloc has |
no errors or vulnerabilities, you can define INSECURE to 1, |
which might (or might not) provide a small performance improvement. |
|
Thread-safety: NOT thread-safe unless USE_LOCKS defined |
When USE_LOCKS is defined, each public call to malloc, free, |
etc is surrounded with either a pthread mutex or a win32 |
spinlock (depending on WIN32). This is not especially fast, and |
can be a major bottleneck. It is designed only to provide |
minimal protection in concurrent environments, and to provide a |
basis for extensions. If you are using malloc in a concurrent |
program, consider instead using ptmalloc, which is derived from |
a version of this malloc. (See http://www.malloc.de). |
|
System requirements: Any combination of MORECORE and/or MMAP/MUNMAP |
This malloc can use unix sbrk or any emulation (invoked using |
the CALL_MORECORE macro) and/or mmap/munmap or any emulation |
(invoked using CALL_MMAP/CALL_MUNMAP) to get and release system |
memory. On most unix systems, it tends to work best if both |
MORECORE and MMAP are enabled. On Win32, it uses emulations |
based on VirtualAlloc. It also uses common C library functions |
like memset. |
|
Compliance: I believe it is compliant with the Single Unix Specification |
(See http://www.unix.org). Also SVID/XPG, ANSI C, and probably |
others as well. |
|
* Overview of algorithms |
|
This is not the fastest, most space-conserving, most portable, or |
most tunable malloc ever written. However it is among the fastest |
while also being among the most space-conserving, portable and |
tunable. Consistent balance across these factors results in a good |
general-purpose allocator for malloc-intensive programs. |
|
In most ways, this malloc is a best-fit allocator. Generally, it |
chooses the best-fitting existing chunk for a request, with ties |
broken in approximately least-recently-used order. (This strategy |
normally maintains low fragmentation.) However, for requests less |
than 256bytes, it deviates from best-fit when there is not an |
exactly fitting available chunk by preferring to use space adjacent |
to that used for the previous small request, as well as by breaking |
ties in approximately most-recently-used order. (These enhance |
locality of series of small allocations.) And for very large requests |
(>= 256Kb by default), it relies on system memory mapping |
facilities, if supported. (This helps avoid carrying around and |
possibly fragmenting memory used only for large chunks.) |
|
All operations (except malloc_stats and mallinfo) have execution |
times that are bounded by a constant factor of the number of bits in |
a size_t, not counting any clearing in calloc or copying in realloc, |
or actions surrounding MORECORE and MMAP that have times |
proportional to the number of non-contiguous regions returned by |
system allocation routines, which is often just 1. |
|
The implementation is not very modular and seriously overuses |
macros. Perhaps someday all C compilers will do as good a job |
inlining modular code as can now be done by brute-force expansion, |
but now, enough of them seem not to. |
|
Some compilers issue a lot of warnings about code that is |
dead/unreachable only on some platforms, and also about intentional |
uses of negation on unsigned types. All known cases of each can be |
ignored. |
|
For a longer but out of date high-level description, see |
http://gee.cs.oswego.edu/dl/html/malloc.html |
|
* MSPACES |
If MSPACES is defined, then in addition to malloc, free, etc., |
this file also defines mspace_malloc, mspace_free, etc. These |
are versions of malloc routines that take an "mspace" argument |
obtained using create_mspace, to control all internal bookkeeping. |
If ONLY_MSPACES is defined, only these versions are compiled. |
So if you would like to use this allocator for only some allocations, |
and your system malloc for others, you can compile with |
ONLY_MSPACES and then do something like... |
static mspace mymspace = create_mspace(0,0); // for example |
#define mymalloc(bytes) mspace_malloc(mymspace, bytes) |
|
(Note: If you only need one instance of an mspace, you can instead |
use "USE_DL_PREFIX" to relabel the global malloc.) |
|
You can similarly create thread-local allocators by storing |
mspaces as thread-locals. For example: |
static __thread mspace tlms = 0; |
void* tlmalloc(size_t bytes) { |
if (tlms == 0) tlms = create_mspace(0, 0); |
return mspace_malloc(tlms, bytes); |
} |
void tlfree(void* mem) { mspace_free(tlms, mem); } |
|
Unless FOOTERS is defined, each mspace is completely independent. |
You cannot allocate from one and free to another (although |
conformance is only weakly checked, so usage errors are not always |
caught). If FOOTERS is defined, then each chunk carries around a tag |
indicating its originating mspace, and frees are directed to their |
originating spaces. |
|
------------------------- Compile-time options --------------------------- |
|
Be careful in setting #define values for numerical constants of type |
size_t. On some systems, literal values are not automatically extended |
to size_t precision unless they are explicitly casted. |
|
WIN32 default: defined if _WIN32 defined |
Defining WIN32 sets up defaults for MS environment and compilers. |
Otherwise defaults are for unix. |
|
MALLOC_ALIGNMENT default: (size_t)8 |
Controls the minimum alignment for malloc'ed chunks. It must be a |
power of two and at least 8, even on machines for which smaller |
alignments would suffice. It may be defined as larger than this |
though. Note however that code and data structures are optimized for |
the case of 8-byte alignment. |
|
MSPACES default: 0 (false) |
If true, compile in support for independent allocation spaces. |
This is only supported if HAVE_MMAP is true. |
|
ONLY_MSPACES default: 0 (false) |
If true, only compile in mspace versions, not regular versions. |
|
USE_LOCKS default: 0 (false) |
Causes each call to each public routine to be surrounded with |
pthread or WIN32 mutex lock/unlock. (If set true, this can be |
overridden on a per-mspace basis for mspace versions.) |
|
FOOTERS default: 0 |
If true, provide extra checking and dispatching by placing |
information in the footers of allocated chunks. This adds |
space and time overhead. |
|
INSECURE default: 0 |
If true, omit checks for usage errors and heap space overwrites. |
|
USE_DL_PREFIX default: NOT defined |
Causes compiler to prefix all public routines with the string 'dl'. |
This can be useful when you only want to use this malloc in one part |
of a program, using your regular system malloc elsewhere. |
|
ABORT default: defined as abort() |
Defines how to abort on failed checks. On most systems, a failed |
check cannot die with an "assert" or even print an informative |
message, because the underlying print routines in turn call malloc, |
which will fail again. Generally, the best policy is to simply call |
abort(). It's not very useful to do more than this because many |
errors due to overwriting will show up as address faults (null, odd |
addresses etc) rather than malloc-triggered checks, so will also |
abort. Also, most compilers know that abort() does not return, so |
can better optimize code conditionally calling it. |
|
PROCEED_ON_ERROR default: defined as 0 (false) |
Controls whether detected bad addresses cause them to bypassed |
rather than aborting. If set, detected bad arguments to free and |
realloc are ignored. And all bookkeeping information is zeroed out |
upon a detected overwrite of freed heap space, thus losing the |
ability to ever return it from malloc again, but enabling the |
application to proceed. If PROCEED_ON_ERROR is defined, the |
static variable malloc_corruption_error_count is compiled in |
and can be examined to see if errors have occurred. This option |
generates slower code than the default abort policy. |
|
DEBUG default: NOT defined |
The DEBUG setting is mainly intended for people trying to modify |
this code or diagnose problems when porting to new platforms. |
However, it may also be able to better isolate user errors than just |
using runtime checks. The assertions in the check routines spell |
out in more detail the assumptions and invariants underlying the |
algorithms. The checking is fairly extensive, and will slow down |
execution noticeably. Calling malloc_stats or mallinfo with DEBUG |
set will attempt to check every non-mmapped allocated and free chunk |
in the course of computing the summaries. |
|
ABORT_ON_ASSERT_FAILURE default: defined as 1 (true) |
Debugging assertion failures can be nearly impossible if your |
version of the assert macro causes malloc to be called, which will |
lead to a cascade of further failures, blowing the runtime stack. |
ABORT_ON_ASSERT_FAILURE cause assertions failures to call abort(), |
which will usually make debugging easier. |
|
MALLOC_FAILURE_ACTION default: sets errno to ENOMEM, or no-op on win32 |
The action to take before "return 0" when malloc fails to be able to |
return memory because there is none available. |
|
HAVE_MORECORE default: 1 (true) unless win32 or ONLY_MSPACES |
True if this system supports sbrk or an emulation of it. |
|
MORECORE default: sbrk |
The name of the sbrk-style system routine to call to obtain more |
memory. See below for guidance on writing custom MORECORE |
functions. The type of the argument to sbrk/MORECORE varies across |
systems. It cannot be size_t, because it supports negative |
arguments, so it is normally the signed type of the same width as |
size_t (sometimes declared as "intptr_t"). It doesn't much matter |
though. Internally, we only call it with arguments less than half |
the max value of a size_t, which should work across all reasonable |
possibilities, although sometimes generating compiler warnings. See |
near the end of this file for guidelines for creating a custom |
version of MORECORE. |
|
MORECORE_CONTIGUOUS default: 1 (true) |
If true, take advantage of fact that consecutive calls to MORECORE |
with positive arguments always return contiguous increasing |
addresses. This is true of unix sbrk. It does not hurt too much to |
set it true anyway, since malloc copes with non-contiguities. |
Setting it false when definitely non-contiguous saves time |
and possibly wasted space it would take to discover this though. |
|
MORECORE_CANNOT_TRIM default: NOT defined |
True if MORECORE cannot release space back to the system when given |
negative arguments. This is generally necessary only if you are |
using a hand-crafted MORECORE function that cannot handle negative |
arguments. |
|
HAVE_MMAP default: 1 (true) |
True if this system supports mmap or an emulation of it. If so, and |
HAVE_MORECORE is not true, MMAP is used for all system |
allocation. If set and HAVE_MORECORE is true as well, MMAP is |
primarily used to directly allocate very large blocks. It is also |
used as a backup strategy in cases where MORECORE fails to provide |
space from system. Note: A single call to MUNMAP is assumed to be |
able to unmap memory that may have be allocated using multiple calls |
to MMAP, so long as they are adjacent. |
|
HAVE_MREMAP default: 1 on linux, else 0 |
If true realloc() uses mremap() to re-allocate large blocks and |
extend or shrink allocation spaces. |
|
MMAP_CLEARS default: 1 on unix |
True if mmap clears memory so calloc doesn't need to. This is true |
for standard unix mmap using /dev/zero. |
|
USE_BUILTIN_FFS default: 0 (i.e., not used) |
Causes malloc to use the builtin ffs() function to compute indices. |
Some compilers may recognize and intrinsify ffs to be faster than the |
supplied C version. Also, the case of x86 using gcc is special-cased |
to an asm instruction, so is already as fast as it can be, and so |
this setting has no effect. (On most x86s, the asm version is only |
slightly faster than the C version.) |
|
malloc_getpagesize default: derive from system includes, or 4096. |
The system page size. To the extent possible, this malloc manages |
memory from the system in page-size units. This may be (and |
usually is) a function rather than a constant. This is ignored |
if WIN32, where page size is determined using getSystemInfo during |
initialization. |
|
USE_DEV_RANDOM default: 0 (i.e., not used) |
Causes malloc to use /dev/random to initialize secure magic seed for |
stamping footers. Otherwise, the current time is used. |
|
NO_MALLINFO default: 0 |
If defined, don't compile "mallinfo". This can be a simple way |
of dealing with mismatches between system declarations and |
those in this file. |
|
MALLINFO_FIELD_TYPE default: size_t |
The type of the fields in the mallinfo struct. This was originally |
defined as "int" in SVID etc, but is more usefully defined as |
size_t. The value is used only if HAVE_USR_INCLUDE_MALLOC_H is not set |
|
REALLOC_ZERO_BYTES_FREES default: not defined |
This should be set if a call to realloc with zero bytes should |
be the same as a call to free. Some people think it should. Otherwise, |
since this malloc returns a unique pointer for malloc(0), so does |
realloc(p, 0). |
|
LACKS_UNISTD_H, LACKS_FCNTL_H, LACKS_SYS_PARAM_H, LACKS_SYS_MMAN_H |
LACKS_STRINGS_H, LACKS_STRING_H, LACKS_SYS_TYPES_H, LACKS_ERRNO_H |
LACKS_STDLIB_H default: NOT defined unless on WIN32 |
Define these if your system does not have these header files. |
You might need to manually insert some of the declarations they provide. |
|
DEFAULT_GRANULARITY default: page size if MORECORE_CONTIGUOUS, |
system_info.dwAllocationGranularity in WIN32, |
otherwise 64K. |
Also settable using mallopt(M_GRANULARITY, x) |
The unit for allocating and deallocating memory from the system. On |
most systems with contiguous MORECORE, there is no reason to |
make this more than a page. However, systems with MMAP tend to |
either require or encourage larger granularities. You can increase |
this value to prevent system allocation functions to be called so |
often, especially if they are slow. The value must be at least one |
page and must be a power of two. Setting to 0 causes initialization |
to either page size or win32 region size. (Note: In previous |
versions of malloc, the equivalent of this option was called |
"TOP_PAD") |
|
DEFAULT_TRIM_THRESHOLD default: 2MB |
Also settable using mallopt(M_TRIM_THRESHOLD, x) |
The maximum amount of unused top-most memory to keep before |
releasing via malloc_trim in free(). Automatic trimming is mainly |
useful in long-lived programs using contiguous MORECORE. Because |
trimming via sbrk can be slow on some systems, and can sometimes be |
wasteful (in cases where programs immediately afterward allocate |
more large chunks) the value should be high enough so that your |
overall system performance would improve by releasing this much |
memory. As a rough guide, you might set to a value close to the |
average size of a process (program) running on your system. |
Releasing this much memory would allow such a process to run in |
memory. Generally, it is worth tuning trim thresholds when a |
program undergoes phases where several large chunks are allocated |
and released in ways that can reuse each other's storage, perhaps |
mixed with phases where there are no such chunks at all. The trim |
value must be greater than page size to have any useful effect. To |
disable trimming completely, you can set to MAX_SIZE_T. Note that the trick |
some people use of mallocing a huge space and then freeing it at |
program startup, in an attempt to reserve system memory, doesn't |
have the intended effect under automatic trimming, since that memory |
will immediately be returned to the system. |
|
DEFAULT_MMAP_THRESHOLD default: 256K |
Also settable using mallopt(M_MMAP_THRESHOLD, x) |
The request size threshold for using MMAP to directly service a |
request. Requests of at least this size that cannot be allocated |
using already-existing space will be serviced via mmap. (If enough |
normal freed space already exists it is used instead.) Using mmap |
segregates relatively large chunks of memory so that they can be |
individually obtained and released from the host system. A request |
serviced through mmap is never reused by any other request (at least |
not directly; the system may just so happen to remap successive |
requests to the same locations). Segregating space in this way has |
the benefits that: Mmapped space can always be individually released |
back to the system, which helps keep the system level memory demands |
of a long-lived program low. Also, mapped memory doesn't become |
`locked' between other chunks, as can happen with normally allocated |
chunks, which means that even trimming via malloc_trim would not |
release them. However, it has the disadvantage that the space |
cannot be reclaimed, consolidated, and then used to service later |
requests, as happens with normal chunks. The advantages of mmap |
nearly always outweigh disadvantages for "large" chunks, but the |
value of "large" may vary across systems. The default is an |
empirically derived value that works well in most systems. You can |
disable mmap by setting to MAX_SIZE_T. |
|
*/ |
|
#ifndef WIN32 |
#ifdef _WIN32 |
#define WIN32 1 |
#endif /* _WIN32 */ |
#endif /* WIN32 */ |
#ifdef WIN32 |
#define WIN32_LEAN_AND_MEAN |
#include <windows.h> |
#define HAVE_MMAP 1 |
#define HAVE_MORECORE 0 |
#define LACKS_UNISTD_H |
#define LACKS_SYS_PARAM_H |
#define LACKS_SYS_MMAN_H |
#define LACKS_STRING_H |
#define LACKS_STRINGS_H |
#define LACKS_SYS_TYPES_H |
#define LACKS_ERRNO_H |
#define MALLOC_FAILURE_ACTION |
#define MMAP_CLEARS 0 /* WINCE and some others apparently don't clear */ |
#endif /* WIN32 */ |
|
#if defined(DARWIN) || defined(_DARWIN) |
/* Mac OSX docs advise not to use sbrk; it seems better to use mmap */ |
#ifndef HAVE_MORECORE |
#define HAVE_MORECORE 0 |
#define HAVE_MMAP 1 |
#endif /* HAVE_MORECORE */ |
#endif /* DARWIN */ |
|
#ifndef LACKS_SYS_TYPES_H |
#include <sys/types.h> /* For size_t */ |
#endif /* LACKS_SYS_TYPES_H */ |
|
/* The maximum possible size_t value has all bits set */ |
#define MAX_SIZE_T (~(size_t)0) |
|
#ifndef ONLY_MSPACES |
#define ONLY_MSPACES 0 |
#endif /* ONLY_MSPACES */ |
#ifndef MSPACES |
#if ONLY_MSPACES |
#define MSPACES 1 |
#else /* ONLY_MSPACES */ |
#define MSPACES 0 |
#endif /* ONLY_MSPACES */ |
#endif /* MSPACES */ |
#ifndef MALLOC_ALIGNMENT |
#define MALLOC_ALIGNMENT ((size_t)8U) |
#endif /* MALLOC_ALIGNMENT */ |
#ifndef FOOTERS |
#define FOOTERS 0 |
#endif /* FOOTERS */ |
#ifndef ABORT |
#define ABORT abort() |
#endif /* ABORT */ |
#ifndef ABORT_ON_ASSERT_FAILURE |
#define ABORT_ON_ASSERT_FAILURE 1 |
#endif /* ABORT_ON_ASSERT_FAILURE */ |
#ifndef PROCEED_ON_ERROR |
#define PROCEED_ON_ERROR 0 |
#endif /* PROCEED_ON_ERROR */ |
#ifndef USE_LOCKS |
#define USE_LOCKS 0 |
#endif /* USE_LOCKS */ |
#ifndef INSECURE |
#define INSECURE 0 |
#endif /* INSECURE */ |
#ifndef HAVE_MMAP |
#define HAVE_MMAP 1 |
#endif /* HAVE_MMAP */ |
#ifndef MMAP_CLEARS |
#define MMAP_CLEARS 1 |
#endif /* MMAP_CLEARS */ |
#ifndef HAVE_MREMAP |
#ifdef linux |
#define HAVE_MREMAP 1 |
#else /* linux */ |
#define HAVE_MREMAP 0 |
#endif /* linux */ |
#endif /* HAVE_MREMAP */ |
#ifndef MALLOC_FAILURE_ACTION |
#define MALLOC_FAILURE_ACTION errno = ENOMEM; |
#endif /* MALLOC_FAILURE_ACTION */ |
#ifndef HAVE_MORECORE |
#if ONLY_MSPACES |
#define HAVE_MORECORE 0 |
#else /* ONLY_MSPACES */ |
#define HAVE_MORECORE 1 |
#endif /* ONLY_MSPACES */ |
#endif /* HAVE_MORECORE */ |
#if !HAVE_MORECORE |
#define MORECORE_CONTIGUOUS 0 |
#else /* !HAVE_MORECORE */ |
#ifndef MORECORE |
#define MORECORE sbrk |
#endif /* MORECORE */ |
#ifndef MORECORE_CONTIGUOUS |
#define MORECORE_CONTIGUOUS 1 |
#endif /* MORECORE_CONTIGUOUS */ |
#endif /* HAVE_MORECORE */ |
#ifndef DEFAULT_GRANULARITY |
#if MORECORE_CONTIGUOUS |
#define DEFAULT_GRANULARITY (0) /* 0 means to compute in init_mparams */ |
#else /* MORECORE_CONTIGUOUS */ |
#define DEFAULT_GRANULARITY ((size_t)64U * (size_t)1024U) |
#endif /* MORECORE_CONTIGUOUS */ |
#endif /* DEFAULT_GRANULARITY */ |
#ifndef DEFAULT_TRIM_THRESHOLD |
#ifndef MORECORE_CANNOT_TRIM |
#define DEFAULT_TRIM_THRESHOLD ((size_t)2U * (size_t)1024U * (size_t)1024U) |
#else /* MORECORE_CANNOT_TRIM */ |
#define DEFAULT_TRIM_THRESHOLD MAX_SIZE_T |
#endif /* MORECORE_CANNOT_TRIM */ |
#endif /* DEFAULT_TRIM_THRESHOLD */ |
#ifndef DEFAULT_MMAP_THRESHOLD |
#if HAVE_MMAP |
#define DEFAULT_MMAP_THRESHOLD ((size_t)256U * (size_t)1024U) |
#else /* HAVE_MMAP */ |
#define DEFAULT_MMAP_THRESHOLD MAX_SIZE_T |
#endif /* HAVE_MMAP */ |
#endif /* DEFAULT_MMAP_THRESHOLD */ |
#ifndef USE_BUILTIN_FFS |
#define USE_BUILTIN_FFS 0 |
#endif /* USE_BUILTIN_FFS */ |
#ifndef USE_DEV_RANDOM |
#define USE_DEV_RANDOM 0 |
#endif /* USE_DEV_RANDOM */ |
#ifndef NO_MALLINFO |
#define NO_MALLINFO 0 |
#endif /* NO_MALLINFO */ |
#ifndef MALLINFO_FIELD_TYPE |
#define MALLINFO_FIELD_TYPE size_t |
#endif /* MALLINFO_FIELD_TYPE */ |
|
/* |
mallopt tuning options. SVID/XPG defines four standard parameter |
numbers for mallopt, normally defined in malloc.h. None of these |
are used in this malloc, so setting them has no effect. But this |
malloc does support the following options. |
*/ |
|
#define M_TRIM_THRESHOLD (-1) |
#define M_GRANULARITY (-2) |
#define M_MMAP_THRESHOLD (-3) |
|
/* ------------------------ Mallinfo declarations ------------------------ */ |
|
#if !NO_MALLINFO |
/* |
This version of malloc supports the standard SVID/XPG mallinfo |
routine that returns a struct containing usage properties and |
statistics. It should work on any system that has a |
/usr/include/malloc.h defining struct mallinfo. The main |
declaration needed is the mallinfo struct that is returned (by-copy) |
by mallinfo(). The malloinfo struct contains a bunch of fields that |
are not even meaningful in this version of malloc. These fields are |
are instead filled by mallinfo() with other numbers that might be of |
interest. |
|
HAVE_USR_INCLUDE_MALLOC_H should be set if you have a |
/usr/include/malloc.h file that includes a declaration of struct |
mallinfo. If so, it is included; else a compliant version is |
declared below. These must be precisely the same for mallinfo() to |
work. The original SVID version of this struct, defined on most |
systems with mallinfo, declares all fields as ints. But some others |
define as unsigned long. If your system defines the fields using a |
type of different width than listed here, you MUST #include your |
system version and #define HAVE_USR_INCLUDE_MALLOC_H. |
*/ |
|
/* #define HAVE_USR_INCLUDE_MALLOC_H */ |
|
#ifdef HAVE_USR_INCLUDE_MALLOC_H |
#include "/usr/include/malloc.h" |
#else /* HAVE_USR_INCLUDE_MALLOC_H */ |
|
struct mallinfo { |
MALLINFO_FIELD_TYPE arena; /* non-mmapped space allocated from system */ |
MALLINFO_FIELD_TYPE ordblks; /* number of free chunks */ |
MALLINFO_FIELD_TYPE smblks; /* always 0 */ |
MALLINFO_FIELD_TYPE hblks; /* always 0 */ |
MALLINFO_FIELD_TYPE hblkhd; /* space in mmapped regions */ |
MALLINFO_FIELD_TYPE usmblks; /* maximum total allocated space */ |
MALLINFO_FIELD_TYPE fsmblks; /* always 0 */ |
MALLINFO_FIELD_TYPE uordblks; /* total allocated space */ |
MALLINFO_FIELD_TYPE fordblks; /* total free space */ |
MALLINFO_FIELD_TYPE keepcost; /* releasable (via malloc_trim) space */ |
}; |
|
#endif /* HAVE_USR_INCLUDE_MALLOC_H */ |
#endif /* NO_MALLINFO */ |
|
#ifdef __cplusplus |
extern "C" { |
#endif /* __cplusplus */ |
|
#if !ONLY_MSPACES |
|
/* ------------------- Declarations of public routines ------------------- */ |
|
#ifndef USE_DL_PREFIX |
#define dlcalloc calloc |
#define dlfree free |
#define dlmalloc malloc |
#define dlmemalign memalign |
#define dlrealloc realloc |
#define dlvalloc valloc |
#define dlpvalloc pvalloc |
#define dlmallinfo mallinfo |
#define dlmallopt mallopt |
#define dlmalloc_trim malloc_trim |
#define dlmalloc_stats malloc_stats |
#define dlmalloc_usable_size malloc_usable_size |
#define dlmalloc_footprint malloc_footprint |
#define dlmalloc_max_footprint malloc_max_footprint |
#define dlindependent_calloc independent_calloc |
#define dlindependent_comalloc independent_comalloc |
#endif /* USE_DL_PREFIX */ |
|
|
/* |
malloc(size_t n) |
Returns a pointer to a newly allocated chunk of at least n bytes, or |
null if no space is available, in which case errno is set to ENOMEM |
on ANSI C systems. |
|
If n is zero, malloc returns a minimum-sized chunk. (The minimum |
size is 16 bytes on most 32bit systems, and 32 bytes on 64bit |
systems.) Note that size_t is an unsigned type, so calls with |
arguments that would be negative if signed are interpreted as |
requests for huge amounts of space, which will often fail. The |
maximum supported value of n differs across systems, but is in all |
cases less than the maximum representable value of a size_t. |
*/ |
void* dlmalloc(size_t); |
|
/* |
free(void* p) |
Releases the chunk of memory pointed to by p, that had been previously |
allocated using malloc or a related routine such as realloc. |
It has no effect if p is null. If p was not malloced or already |
freed, free(p) will by default cause the current program to abort. |
*/ |
void dlfree(void*); |
|
/* |
calloc(size_t n_elements, size_t element_size); |
Returns a pointer to n_elements * element_size bytes, with all locations |
set to zero. |
*/ |
void* dlcalloc(size_t, size_t); |
|
/* |
realloc(void* p, size_t n) |
Returns a pointer to a chunk of size n that contains the same data |
as does chunk p up to the minimum of (n, p's size) bytes, or null |
if no space is available. |
|
The returned pointer may or may not be the same as p. The algorithm |
prefers extending p in most cases when possible, otherwise it |
employs the equivalent of a malloc-copy-free sequence. |
|
If p is null, realloc is equivalent to malloc. |
|
If space is not available, realloc returns null, errno is set (if on |
ANSI) and p is NOT freed. |
|
if n is for fewer bytes than already held by p, the newly unused |
space is lopped off and freed if possible. realloc with a size |
argument of zero (re)allocates a minimum-sized chunk. |
|
The old unix realloc convention of allowing the last-free'd chunk |
to be used as an argument to realloc is not supported. |
*/ |
|
void* dlrealloc(void*, size_t); |
|
/* |
memalign(size_t alignment, size_t n); |
Returns a pointer to a newly allocated chunk of n bytes, aligned |
in accord with the alignment argument. |
|
The alignment argument should be a power of two. If the argument is |
not a power of two, the nearest greater power is used. |
8-byte alignment is guaranteed by normal malloc calls, so don't |
bother calling memalign with an argument of 8 or less. |
|
Overreliance on memalign is a sure way to fragment space. |
*/ |
void* dlmemalign(size_t, size_t); |
|
/* |
valloc(size_t n); |
Equivalent to memalign(pagesize, n), where pagesize is the page |
size of the system. If the pagesize is unknown, 4096 is used. |
*/ |
void* dlvalloc(size_t); |
|
/* |
mallopt(int parameter_number, int parameter_value) |
Sets tunable parameters The format is to provide a |
(parameter-number, parameter-value) pair. mallopt then sets the |
corresponding parameter to the argument value if it can (i.e., so |
long as the value is meaningful), and returns 1 if successful else |
0. SVID/XPG/ANSI defines four standard param numbers for mallopt, |
normally defined in malloc.h. None of these are use in this malloc, |
so setting them has no effect. But this malloc also supports other |
options in mallopt. See below for details. Briefly, supported |
parameters are as follows (listed defaults are for "typical" |
configurations). |
|
Symbol param # default allowed param values |
M_TRIM_THRESHOLD -1 2*1024*1024 any (MAX_SIZE_T disables) |
M_GRANULARITY -2 page size any power of 2 >= page size |
M_MMAP_THRESHOLD -3 256*1024 any (or 0 if no MMAP support) |
*/ |
int dlmallopt(int, int); |
|
/* |
malloc_footprint(); |
Returns the number of bytes obtained from the system. The total |
number of bytes allocated by malloc, realloc etc., is less than this |
value. Unlike mallinfo, this function returns only a precomputed |
result, so can be called frequently to monitor memory consumption. |
Even if locks are otherwise defined, this function does not use them, |
so results might not be up to date. |
*/ |
size_t dlmalloc_footprint(void); |
|
/* |
malloc_max_footprint(); |
Returns the maximum number of bytes obtained from the system. This |
value will be greater than current footprint if deallocated space |
has been reclaimed by the system. The peak number of bytes allocated |
by malloc, realloc etc., is less than this value. Unlike mallinfo, |
this function returns only a precomputed result, so can be called |
frequently to monitor memory consumption. Even if locks are |
otherwise defined, this function does not use them, so results might |
not be up to date. |
*/ |
size_t dlmalloc_max_footprint(void); |
|
#if !NO_MALLINFO |
/* |
mallinfo() |
Returns (by copy) a struct containing various summary statistics: |
|
arena: current total non-mmapped bytes allocated from system |
ordblks: the number of free chunks |
smblks: always zero. |
hblks: current number of mmapped regions |
hblkhd: total bytes held in mmapped regions |
usmblks: the maximum total allocated space. This will be greater |
than current total if trimming has occurred. |
fsmblks: always zero |
uordblks: current total allocated space (normal or mmapped) |
fordblks: total free space |
keepcost: the maximum number of bytes that could ideally be released |
back to system via malloc_trim. ("ideally" means that |
it ignores page restrictions etc.) |
|
Because these fields are ints, but internal bookkeeping may |
be kept as longs, the reported values may wrap around zero and |
thus be inaccurate. |
*/ |
struct mallinfo dlmallinfo(void); |
#endif /* NO_MALLINFO */ |
|
/* |
independent_calloc(size_t n_elements, size_t element_size, void* chunks[]); |
|
independent_calloc is similar to calloc, but instead of returning a |
single cleared space, it returns an array of pointers to n_elements |
independent elements that can hold contents of size elem_size, each |
of which starts out cleared, and can be independently freed, |
realloc'ed etc. The elements are guaranteed to be adjacently |
allocated (this is not guaranteed to occur with multiple callocs or |
mallocs), which may also improve cache locality in some |
applications. |
|
The "chunks" argument is optional (i.e., may be null, which is |
probably the most typical usage). If it is null, the returned array |
is itself dynamically allocated and should also be freed when it is |
no longer needed. Otherwise, the chunks array must be of at least |
n_elements in length. It is filled in with the pointers to the |
chunks. |
|
In either case, independent_calloc returns this pointer array, or |
null if the allocation failed. If n_elements is zero and "chunks" |
is null, it returns a chunk representing an array with zero elements |
(which should be freed if not wanted). |
|
Each element must be individually freed when it is no longer |
needed. If you'd like to instead be able to free all at once, you |
should instead use regular calloc and assign pointers into this |
space to represent elements. (In this case though, you cannot |
independently free elements.) |
|
independent_calloc simplifies and speeds up implementations of many |
kinds of pools. It may also be useful when constructing large data |
structures that initially have a fixed number of fixed-sized nodes, |
but the number is not known at compile time, and some of the nodes |
may later need to be freed. For example: |
|
struct Node { int item; struct Node* next; }; |
|
struct Node* build_list() { |
struct Node** pool; |
int n = read_number_of_nodes_needed(); |
if (n <= 0) return 0; |
pool = (struct Node**)(independent_calloc(n, sizeof(struct Node), 0); |
if (pool == 0) die(); |
// organize into a linked list... |
struct Node* first = pool[0]; |
for (i = 0; i < n-1; ++i) |
pool[i]->next = pool[i+1]; |
free(pool); // Can now free the array (or not, if it is needed later) |
return first; |
} |
*/ |
void** dlindependent_calloc(size_t, size_t, void**); |
|
/* |
independent_comalloc(size_t n_elements, size_t sizes[], void* chunks[]); |
|
independent_comalloc allocates, all at once, a set of n_elements |
chunks with sizes indicated in the "sizes" array. It returns |
an array of pointers to these elements, each of which can be |
independently freed, realloc'ed etc. The elements are guaranteed to |
be adjacently allocated (this is not guaranteed to occur with |
multiple callocs or mallocs), which may also improve cache locality |
in some applications. |
|
The "chunks" argument is optional (i.e., may be null). If it is null |
the returned array is itself dynamically allocated and should also |
be freed when it is no longer needed. Otherwise, the chunks array |
must be of at least n_elements in length. It is filled in with the |
pointers to the chunks. |
|
In either case, independent_comalloc returns this pointer array, or |
null if the allocation failed. If n_elements is zero and chunks is |
null, it returns a chunk representing an array with zero elements |
(which should be freed if not wanted). |
|
Each element must be individually freed when it is no longer |
needed. If you'd like to instead be able to free all at once, you |
should instead use a single regular malloc, and assign pointers at |
particular offsets in the aggregate space. (In this case though, you |
cannot independently free elements.) |
|
independent_comallac differs from independent_calloc in that each |
element may have a different size, and also that it does not |
automatically clear elements. |
|
independent_comalloc can be used to speed up allocation in cases |
where several structs or objects must always be allocated at the |
same time. For example: |
|
struct Head { ... } |
struct Foot { ... } |
|
void send_message(char* msg) { |
int msglen = strlen(msg); |
size_t sizes[3] = { sizeof(struct Head), msglen, sizeof(struct Foot) }; |
void* chunks[3]; |
if (independent_comalloc(3, sizes, chunks) == 0) |
die(); |
struct Head* head = (struct Head*)(chunks[0]); |
char* body = (char*)(chunks[1]); |
struct Foot* foot = (struct Foot*)(chunks[2]); |
// ... |
} |
|
In general though, independent_comalloc is worth using only for |
larger values of n_elements. For small values, you probably won't |
detect enough difference from series of malloc calls to bother. |
|
Overuse of independent_comalloc can increase overall memory usage, |
since it cannot reuse existing noncontiguous small chunks that |
might be available for some of the elements. |
*/ |
void** dlindependent_comalloc(size_t, size_t*, void**); |
|
|
/* |
pvalloc(size_t n); |
Equivalent to valloc(minimum-page-that-holds(n)), that is, |
round up n to nearest pagesize. |
*/ |
void* dlpvalloc(size_t); |
|
/* |
malloc_trim(size_t pad); |
|
If possible, gives memory back to the system (via negative arguments |
to sbrk) if there is unused memory at the `high' end of the malloc |
pool or in unused MMAP segments. You can call this after freeing |
large blocks of memory to potentially reduce the system-level memory |
requirements of a program. However, it cannot guarantee to reduce |
memory. Under some allocation patterns, some large free blocks of |
memory will be locked between two used chunks, so they cannot be |
given back to the system. |
|
The `pad' argument to malloc_trim represents the amount of free |
trailing space to leave untrimmed. If this argument is zero, only |
the minimum amount of memory to maintain internal data structures |
will be left. Non-zero arguments can be supplied to maintain enough |
trailing space to service future expected allocations without having |
to re-obtain memory from the system. |
|
Malloc_trim returns 1 if it actually released any memory, else 0. |
*/ |
int dlmalloc_trim(size_t); |
|
/* |
malloc_usable_size(void* p); |
|
Returns the number of bytes you can actually use in |
an allocated chunk, which may be more than you requested (although |
often not) due to alignment and minimum size constraints. |
You can use this many bytes without worrying about |
overwriting other allocated objects. This is not a particularly great |
programming practice. malloc_usable_size can be more useful in |
debugging and assertions, for example: |
|
p = malloc(n); |
assert(malloc_usable_size(p) >= 256); |
*/ |
size_t dlmalloc_usable_size(void*); |
|
/* |
malloc_stats(); |
Prints on stderr the amount of space obtained from the system (both |
via sbrk and mmap), the maximum amount (which may be more than |
current if malloc_trim and/or munmap got called), and the current |
number of bytes allocated via malloc (or realloc, etc) but not yet |
freed. Note that this is the number of bytes allocated, not the |
number requested. It will be larger than the number requested |
because of alignment and bookkeeping overhead. Because it includes |
alignment wastage as being in use, this figure may be greater than |
zero even when no user-level chunks are allocated. |
|
The reported current and maximum system memory can be inaccurate if |
a program makes other calls to system memory allocation functions |
(normally sbrk) outside of malloc. |
|
malloc_stats prints only the most commonly interesting statistics. |
More information can be obtained by calling mallinfo. |
*/ |
void dlmalloc_stats(void); |
|
#endif /* ONLY_MSPACES */ |
|
#if MSPACES |
|
/* |
mspace is an opaque type representing an independent |
region of space that supports mspace_malloc, etc. |
*/ |
typedef void* mspace; |
|
/* |
create_mspace creates and returns a new independent space with the |
given initial capacity, or, if 0, the default granularity size. It |
returns null if there is no system memory available to create the |
space. If argument locked is non-zero, the space uses a separate |
lock to control access. The capacity of the space will grow |
dynamically as needed to service mspace_malloc requests. You can |
control the sizes of incremental increases of this space by |
compiling with a different DEFAULT_GRANULARITY or dynamically |
setting with mallopt(M_GRANULARITY, value). |
*/ |
mspace create_mspace(size_t capacity, int locked); |
|
/* |
destroy_mspace destroys the given space, and attempts to return all |
of its memory back to the system, returning the total number of |
bytes freed. After destruction, the results of access to all memory |
used by the space become undefined. |
*/ |
size_t destroy_mspace(mspace msp); |
|
/* |
create_mspace_with_base uses the memory supplied as the initial base |
of a new mspace. Part (less than 128*sizeof(size_t) bytes) of this |
space is used for bookkeeping, so the capacity must be at least this |
large. (Otherwise 0 is returned.) When this initial space is |
exhausted, additional memory will be obtained from the system. |
Destroying this space will deallocate all additionally allocated |
space (if possible) but not the initial base. |
*/ |
mspace create_mspace_with_base(void* base, size_t capacity, int locked); |
|
/* |
mspace_malloc behaves as malloc, but operates within |
the given space. |
*/ |
void* mspace_malloc(mspace msp, size_t bytes); |
|
/* |
mspace_free behaves as free, but operates within |
the given space. |
|
If compiled with FOOTERS==1, mspace_free is not actually needed. |
free may be called instead of mspace_free because freed chunks from |
any space are handled by their originating spaces. |
*/ |
void mspace_free(mspace msp, void* mem); |
|
/* |
mspace_realloc behaves as realloc, but operates within |
the given space. |
|
If compiled with FOOTERS==1, mspace_realloc is not actually |
needed. realloc may be called instead of mspace_realloc because |
realloced chunks from any space are handled by their originating |
spaces. |
*/ |
void* mspace_realloc(mspace msp, void* mem, size_t newsize); |
|
/* |
mspace_calloc behaves as calloc, but operates within |
the given space. |
*/ |
void* mspace_calloc(mspace msp, size_t n_elements, size_t elem_size); |
|
/* |
mspace_memalign behaves as memalign, but operates within |
the given space. |
*/ |
void* mspace_memalign(mspace msp, size_t alignment, size_t bytes); |
|
/* |
mspace_independent_calloc behaves as independent_calloc, but |
operates within the given space. |
*/ |
void** mspace_independent_calloc(mspace msp, size_t n_elements, |
size_t elem_size, void* chunks[]); |
|
/* |
mspace_independent_comalloc behaves as independent_comalloc, but |
operates within the given space. |
*/ |
void** mspace_independent_comalloc(mspace msp, size_t n_elements, |
size_t sizes[], void* chunks[]); |
|
/* |
mspace_footprint() returns the number of bytes obtained from the |
system for this space. |
*/ |
size_t mspace_footprint(mspace msp); |
|
/* |
mspace_max_footprint() returns the peak number of bytes obtained from the |
system for this space. |
*/ |
size_t mspace_max_footprint(mspace msp); |
|
|
#if !NO_MALLINFO |
/* |
mspace_mallinfo behaves as mallinfo, but reports properties of |
the given space. |
*/ |
struct mallinfo mspace_mallinfo(mspace msp); |
#endif /* NO_MALLINFO */ |
|
/* |
mspace_malloc_stats behaves as malloc_stats, but reports |
properties of the given space. |
*/ |
void mspace_malloc_stats(mspace msp); |
|
/* |
mspace_trim behaves as malloc_trim, but |
operates within the given space. |
*/ |
int mspace_trim(mspace msp, size_t pad); |
|
/* |
An alias for mallopt. |
*/ |
int mspace_mallopt(int, int); |
|
#endif /* MSPACES */ |
|
#ifdef __cplusplus |
}; /* end of extern "C" */ |
#endif /* __cplusplus */ |
|
/* |
======================================================================== |
To make a fully customizable malloc.h header file, cut everything |
above this line, put into file malloc.h, edit to suit, and #include it |
on the next line, as well as in programs that use this malloc. |
======================================================================== |
*/ |
|
/* #include "malloc.h" */ |
|
/*------------------------------ internal #includes ---------------------- */ |
|
#ifdef WIN32 |
#pragma warning( disable : 4146 ) /* no "unsigned" warnings */ |
#endif /* WIN32 */ |
|
#include <stdio.h> /* for printing in malloc_stats */ |
|
#ifndef LACKS_ERRNO_H |
#include <errno.h> /* for MALLOC_FAILURE_ACTION */ |
#endif /* LACKS_ERRNO_H */ |
#if FOOTERS |
#include <time.h> /* for magic initialization */ |
#endif /* FOOTERS */ |
#ifndef LACKS_STDLIB_H |
#include <stdlib.h> /* for abort() */ |
#endif /* LACKS_STDLIB_H */ |
#ifdef DEBUG |
#if ABORT_ON_ASSERT_FAILURE |
#define assert(x) if(!(x)) ABORT |
#else /* ABORT_ON_ASSERT_FAILURE */ |
#include <assert.h> |
#endif /* ABORT_ON_ASSERT_FAILURE */ |
#else /* DEBUG */ |
#define assert(x) |
#endif /* DEBUG */ |
#ifndef LACKS_STRING_H |
#include <string.h> /* for memset etc */ |
#endif /* LACKS_STRING_H */ |
#if USE_BUILTIN_FFS |
#ifndef LACKS_STRINGS_H |
#include <strings.h> /* for ffs */ |
#endif /* LACKS_STRINGS_H */ |
#endif /* USE_BUILTIN_FFS */ |
#if HAVE_MMAP |
#ifndef LACKS_SYS_MMAN_H |
#include <sys/mman.h> /* for mmap */ |
#endif /* LACKS_SYS_MMAN_H */ |
#ifndef LACKS_FCNTL_H |
#include <fcntl.h> |
#endif /* LACKS_FCNTL_H */ |
#endif /* HAVE_MMAP */ |
#if HAVE_MORECORE |
#ifndef LACKS_UNISTD_H |
#include <unistd.h> /* for sbrk */ |
#else /* LACKS_UNISTD_H */ |
#if !defined(__FreeBSD__) && !defined(__OpenBSD__) && !defined(__NetBSD__) |
extern void* sbrk(ptrdiff_t); |
#endif /* FreeBSD etc */ |
#endif /* LACKS_UNISTD_H */ |
#endif /* HAVE_MMAP */ |
|
#ifndef WIN32 |
#ifndef malloc_getpagesize |
# ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */ |
# ifndef _SC_PAGE_SIZE |
# define _SC_PAGE_SIZE _SC_PAGESIZE |
# endif |
# endif |
# ifdef _SC_PAGE_SIZE |
# define malloc_getpagesize sysconf(_SC_PAGE_SIZE) |
# else |
# if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE) |
extern size_t getpagesize(); |
# define malloc_getpagesize getpagesize() |
# else |
# ifdef WIN32 /* use supplied emulation of getpagesize */ |
# define malloc_getpagesize getpagesize() |
# else |
# ifndef LACKS_SYS_PARAM_H |
# include <sys/param.h> |
# endif |
# ifdef EXEC_PAGESIZE |
# define malloc_getpagesize EXEC_PAGESIZE |
# else |
# ifdef NBPG |
# ifndef CLSIZE |
# define malloc_getpagesize NBPG |
# else |
# define malloc_getpagesize (NBPG * CLSIZE) |
# endif |
# else |
# ifdef NBPC |
# define malloc_getpagesize NBPC |
# else |
# ifdef PAGESIZE |
# define malloc_getpagesize PAGESIZE |
# else /* just guess */ |
# define malloc_getpagesize ((size_t)4096U) |
# endif |
# endif |
# endif |
# endif |
# endif |
# endif |
# endif |
#endif |
#endif |
|
/* ------------------- size_t and alignment properties -------------------- */ |
|
/* The byte and bit size of a size_t */ |
#define SIZE_T_SIZE (sizeof(size_t)) |
#define SIZE_T_BITSIZE (sizeof(size_t) << 3) |
|
/* Some constants coerced to size_t */ |
/* Annoying but necessary to avoid errors on some plaftorms */ |
#define SIZE_T_ZERO ((size_t)0) |
#define SIZE_T_ONE ((size_t)1) |
#define SIZE_T_TWO ((size_t)2) |
#define TWO_SIZE_T_SIZES (SIZE_T_SIZE<<1) |
#define FOUR_SIZE_T_SIZES (SIZE_T_SIZE<<2) |
#define SIX_SIZE_T_SIZES (FOUR_SIZE_T_SIZES+TWO_SIZE_T_SIZES) |
#define HALF_MAX_SIZE_T (MAX_SIZE_T / 2U) |
|
/* The bit mask value corresponding to MALLOC_ALIGNMENT */ |
#define CHUNK_ALIGN_MASK (MALLOC_ALIGNMENT - SIZE_T_ONE) |
|
/* True if address a has acceptable alignment */ |
#define is_aligned(A) (((size_t)((A)) & (CHUNK_ALIGN_MASK)) == 0) |
|
/* the number of bytes to offset an address to align it */ |
#define align_offset(A)\ |
((((size_t)(A) & CHUNK_ALIGN_MASK) == 0)? 0 :\ |
((MALLOC_ALIGNMENT - ((size_t)(A) & CHUNK_ALIGN_MASK)) & CHUNK_ALIGN_MASK)) |
|
/* -------------------------- MMAP preliminaries ------------------------- */ |
|
/* |
If HAVE_MORECORE or HAVE_MMAP are false, we just define calls and |
checks to fail so compiler optimizer can delete code rather than |
using so many "#if"s. |
*/ |
|
|
/* MORECORE and MMAP must return MFAIL on failure */ |
#define MFAIL ((void*)(MAX_SIZE_T)) |
#define CMFAIL ((char*)(MFAIL)) /* defined for convenience */ |
|
#if !HAVE_MMAP |
#define IS_MMAPPED_BIT (SIZE_T_ZERO) |
#define USE_MMAP_BIT (SIZE_T_ZERO) |
#define CALL_MMAP(s) MFAIL |
#define CALL_MUNMAP(a, s) (-1) |
#define DIRECT_MMAP(s) MFAIL |
|
#else /* HAVE_MMAP */ |
#define IS_MMAPPED_BIT (SIZE_T_ONE) |
#define USE_MMAP_BIT (SIZE_T_ONE) |
|
#ifndef WIN32 |
#define CALL_MUNMAP(a, s) munmap((a), (s)) |
#define MMAP_PROT (PROT_READ|PROT_WRITE) |
#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON) |
#define MAP_ANONYMOUS MAP_ANON |
#endif /* MAP_ANON */ |
#ifdef MAP_ANONYMOUS |
#define MMAP_FLAGS (MAP_PRIVATE|MAP_ANONYMOUS) |
#define CALL_MMAP(s) mmap(0, (s), MMAP_PROT, MMAP_FLAGS, -1, 0) |
#else /* MAP_ANONYMOUS */ |
/* |
Nearly all versions of mmap support MAP_ANONYMOUS, so the following |
is unlikely to be needed, but is supplied just in case. |
*/ |
#define MMAP_FLAGS (MAP_PRIVATE) |
static int dev_zero_fd = -1; /* Cached file descriptor for /dev/zero. */ |
#define CALL_MMAP(s) ((dev_zero_fd < 0) ? \ |
(dev_zero_fd = open("/dev/zero", O_RDWR), \ |
mmap(0, (s), MMAP_PROT, MMAP_FLAGS, dev_zero_fd, 0)) : \ |
mmap(0, (s), MMAP_PROT, MMAP_FLAGS, dev_zero_fd, 0)) |
#endif /* MAP_ANONYMOUS */ |
|
#define DIRECT_MMAP(s) CALL_MMAP(s) |
#else /* WIN32 */ |
|
/* Win32 MMAP via VirtualAlloc */ |
static void* win32mmap(size_t size) { |
void* ptr = VirtualAlloc(0, size, MEM_RESERVE|MEM_COMMIT, PAGE_READWRITE); |
return (ptr != 0)? ptr: MFAIL; |
} |
|
/* For direct MMAP, use MEM_TOP_DOWN to minimize interference */ |
static void* win32direct_mmap(size_t size) { |
void* ptr = VirtualAlloc(0, size, MEM_RESERVE|MEM_COMMIT|MEM_TOP_DOWN, |
PAGE_READWRITE); |
return (ptr != 0)? ptr: MFAIL; |
} |
|
/* This function supports releasing coalesed segments */ |
static int win32munmap(void* ptr, size_t size) { |
MEMORY_BASIC_INFORMATION minfo; |
char* cptr = ptr; |
while (size) { |
if (VirtualQuery(cptr, &minfo, sizeof(minfo)) == 0) |
return -1; |
if (minfo.BaseAddress != cptr || minfo.AllocationBase != cptr || |
minfo.State != MEM_COMMIT || minfo.RegionSize > size) |
return -1; |
if (VirtualFree(cptr, 0, MEM_RELEASE) == 0) |
return -1; |
cptr += minfo.RegionSize; |
size -= minfo.RegionSize; |
} |
return 0; |
} |
|
#define CALL_MMAP(s) win32mmap(s) |
#define CALL_MUNMAP(a, s) win32munmap((a), (s)) |
#define DIRECT_MMAP(s) win32direct_mmap(s) |
#endif /* WIN32 */ |
#endif /* HAVE_MMAP */ |
|
#if HAVE_MMAP && HAVE_MREMAP |
#define CALL_MREMAP(addr, osz, nsz, mv) mremap((addr), (osz), (nsz), (mv)) |
#else /* HAVE_MMAP && HAVE_MREMAP */ |
#define CALL_MREMAP(addr, osz, nsz, mv) MFAIL |
#endif /* HAVE_MMAP && HAVE_MREMAP */ |
|
#if HAVE_MORECORE |
#define CALL_MORECORE(S) MORECORE(S) |
#else /* HAVE_MORECORE */ |
#define CALL_MORECORE(S) MFAIL |
#endif /* HAVE_MORECORE */ |
|
/* mstate bit set if continguous morecore disabled or failed */ |
#define USE_NONCONTIGUOUS_BIT (4U) |
|
/* segment bit set in create_mspace_with_base */ |
#define EXTERN_BIT (8U) |
|
|
/* --------------------------- Lock preliminaries ------------------------ */ |
|
#if USE_LOCKS |
|
/* |
When locks are defined, there are up to two global locks: |
|
* If HAVE_MORECORE, morecore_mutex protects sequences of calls to |
MORECORE. In many cases sys_alloc requires two calls, that should |
not be interleaved with calls by other threads. This does not |
protect against direct calls to MORECORE by other threads not |
using this lock, so there is still code to cope the best we can on |
interference. |
|
* magic_init_mutex ensures that mparams.magic and other |
unique mparams values are initialized only once. |
*/ |
|
#ifndef WIN32 |
/* By default use posix locks */ |
#include <pthread.h> |
#define MLOCK_T pthread_mutex_t |
#define INITIAL_LOCK(l) pthread_mutex_init(l, NULL) |
#define ACQUIRE_LOCK(l) pthread_mutex_lock(l) |
#define RELEASE_LOCK(l) pthread_mutex_unlock(l) |
|
#if HAVE_MORECORE |
static MLOCK_T morecore_mutex = PTHREAD_MUTEX_INITIALIZER; |
#endif /* HAVE_MORECORE */ |
|
static MLOCK_T magic_init_mutex = PTHREAD_MUTEX_INITIALIZER; |
|
#else /* WIN32 */ |
/* |
Because lock-protected regions have bounded times, and there |
are no recursive lock calls, we can use simple spinlocks. |
*/ |
|
#define MLOCK_T long |
static int win32_acquire_lock (MLOCK_T *sl) { |
for (;;) { |
#ifdef InterlockedCompareExchangePointer |
if (!InterlockedCompareExchange(sl, 1, 0)) |
return 0; |
#else /* Use older void* version */ |
if (!InterlockedCompareExchange((void**)sl, (void*)1, (void*)0)) |
return 0; |
#endif /* InterlockedCompareExchangePointer */ |
Sleep (0); |
} |
} |
|
static void win32_release_lock (MLOCK_T *sl) { |
InterlockedExchange (sl, 0); |
} |
|
#define INITIAL_LOCK(l) *(l)=0 |
#define ACQUIRE_LOCK(l) win32_acquire_lock(l) |
#define RELEASE_LOCK(l) win32_release_lock(l) |
#if HAVE_MORECORE |
static MLOCK_T morecore_mutex; |
#endif /* HAVE_MORECORE */ |
static MLOCK_T magic_init_mutex; |
#endif /* WIN32 */ |
|
#define USE_LOCK_BIT (2U) |
#else /* USE_LOCKS */ |
#define USE_LOCK_BIT (0U) |
#define INITIAL_LOCK(l) |
#endif /* USE_LOCKS */ |
|
#if USE_LOCKS && HAVE_MORECORE |
#define ACQUIRE_MORECORE_LOCK() ACQUIRE_LOCK(&morecore_mutex); |
#define RELEASE_MORECORE_LOCK() RELEASE_LOCK(&morecore_mutex); |
#else /* USE_LOCKS && HAVE_MORECORE */ |
#define ACQUIRE_MORECORE_LOCK() |
#define RELEASE_MORECORE_LOCK() |
#endif /* USE_LOCKS && HAVE_MORECORE */ |
|
#if USE_LOCKS |
#define ACQUIRE_MAGIC_INIT_LOCK() ACQUIRE_LOCK(&magic_init_mutex); |
#define RELEASE_MAGIC_INIT_LOCK() RELEASE_LOCK(&magic_init_mutex); |
#else /* USE_LOCKS */ |
#define ACQUIRE_MAGIC_INIT_LOCK() |
#define RELEASE_MAGIC_INIT_LOCK() |
#endif /* USE_LOCKS */ |
|
|
/* ----------------------- Chunk representations ------------------------ */ |
|
/* |
(The following includes lightly edited explanations by Colin Plumb.) |
|
The malloc_chunk declaration below is misleading (but accurate and |
necessary). It declares a "view" into memory allowing access to |
necessary fields at known offsets from a given base. |
|
Chunks of memory are maintained using a `boundary tag' method as |
originally described by Knuth. (See the paper by Paul Wilson |
ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a survey of such |
techniques.) Sizes of free chunks are stored both in the front of |
each chunk and at the end. This makes consolidating fragmented |
chunks into bigger chunks fast. The head fields also hold bits |
representing whether chunks are free or in use. |
|
Here are some pictures to make it clearer. They are "exploded" to |
show that the state of a chunk can be thought of as extending from |
the high 31 bits of the head field of its header through the |
prev_foot and PINUSE_BIT bit of the following chunk header. |
|
A chunk that's in use looks like: |
|
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Size of previous chunk (if P = 1) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |P| |
| Size of this chunk 1| +-+ |
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | |
+- -+ |
| | |
+- -+ |
| : |
+- size - sizeof(size_t) available payload bytes -+ |
: | |
chunk-> +- -+ |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1| |
| Size of next chunk (may or may not be in use) | +-+ |
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
|
And if it's free, it looks like this: |
|
chunk-> +- -+ |
| User payload (must be in use, or we would have merged!) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |P| |
| Size of this chunk 0| +-+ |
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Next pointer | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Prev pointer | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| : |
+- size - sizeof(struct chunk) unused bytes -+ |
: | |
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Size of this chunk | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| |
| Size of next chunk (must be in use, or we would have merged)| +-+ |
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| : |
+- User payload -+ |
: | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
|0| |
+-+ |
Note that since we always merge adjacent free chunks, the chunks |
adjacent to a free chunk must be in use. |
|
Given a pointer to a chunk (which can be derived trivially from the |
payload pointer) we can, in O(1) time, find out whether the adjacent |
chunks are free, and if so, unlink them from the lists that they |
are on and merge them with the current chunk. |
|
Chunks always begin on even word boundaries, so the mem portion |
(which is returned to the user) is also on an even word boundary, and |
thus at least double-word aligned. |
|
The P (PINUSE_BIT) bit, stored in the unused low-order bit of the |
chunk size (which is always a multiple of two words), is an in-use |
bit for the *previous* chunk. If that bit is *clear*, then the |
word before the current chunk size contains the previous chunk |
size, and can be used to find the front of the previous chunk. |
The very first chunk allocated always has this bit set, preventing |
access to non-existent (or non-owned) memory. If pinuse is set for |
any given chunk, then you CANNOT determine the size of the |
previous chunk, and might even get a memory addressing fault when |
trying to do so. |
|
The C (CINUSE_BIT) bit, stored in the unused second-lowest bit of |
the chunk size redundantly records whether the current chunk is |
inuse. This redundancy enables usage checks within free and realloc, |
and reduces indirection when freeing and consolidating chunks. |
|
Each freshly allocated chunk must have both cinuse and pinuse set. |
That is, each allocated chunk borders either a previously allocated |
and still in-use chunk, or the base of its memory arena. This is |
ensured by making all allocations from the the `lowest' part of any |
found chunk. Further, no free chunk physically borders another one, |
so each free chunk is known to be preceded and followed by either |
inuse chunks or the ends of memory. |
|
Note that the `foot' of the current chunk is actually represented |
as the prev_foot of the NEXT chunk. This makes it easier to |
deal with alignments etc but can be very confusing when trying |
to extend or adapt this code. |
|
The exceptions to all this are |
|
1. The special chunk `top' is the top-most available chunk (i.e., |
the one bordering the end of available memory). It is treated |
specially. Top is never included in any bin, is used only if |
no other chunk is available, and is released back to the |
system if it is very large (see M_TRIM_THRESHOLD). In effect, |
the top chunk is treated as larger (and thus less well |
fitting) than any other available chunk. The top chunk |
doesn't update its trailing size field since there is no next |
contiguous chunk that would have to index off it. However, |
space is still allocated for it (TOP_FOOT_SIZE) to enable |
separation or merging when space is extended. |
|
3. Chunks allocated via mmap, which have the lowest-order bit |
(IS_MMAPPED_BIT) set in their prev_foot fields, and do not set |
PINUSE_BIT in their head fields. Because they are allocated |
one-by-one, each must carry its own prev_foot field, which is |
also used to hold the offset this chunk has within its mmapped |
region, which is needed to preserve alignment. Each mmapped |
chunk is trailed by the first two fields of a fake next-chunk |
for sake of usage checks. |
|
*/ |
|
struct malloc_chunk { |
size_t prev_foot; /* Size of previous chunk (if free). */ |
size_t head; /* Size and inuse bits. */ |
struct malloc_chunk* fd; /* double links -- used only if free. */ |
struct malloc_chunk* bk; |
}; |
|
typedef struct malloc_chunk mchunk; |
typedef struct malloc_chunk* mchunkptr; |
typedef struct malloc_chunk* sbinptr; /* The type of bins of chunks */ |
typedef unsigned int bindex_t; /* Described below */ |
typedef unsigned int binmap_t; /* Described below */ |
typedef unsigned int flag_t; /* The type of various bit flag sets */ |
|
/* ------------------- Chunks sizes and alignments ----------------------- */ |
|
#define MCHUNK_SIZE (sizeof(mchunk)) |
|
#if FOOTERS |
#define CHUNK_OVERHEAD (TWO_SIZE_T_SIZES) |
#else /* FOOTERS */ |
#define CHUNK_OVERHEAD (SIZE_T_SIZE) |
#endif /* FOOTERS */ |
|
/* MMapped chunks need a second word of overhead ... */ |
#define MMAP_CHUNK_OVERHEAD (TWO_SIZE_T_SIZES) |
/* ... and additional padding for fake next-chunk at foot */ |
#define MMAP_FOOT_PAD (FOUR_SIZE_T_SIZES) |
|
/* The smallest size we can malloc is an aligned minimal chunk */ |
#define MIN_CHUNK_SIZE\ |
((MCHUNK_SIZE + CHUNK_ALIGN_MASK) & ~CHUNK_ALIGN_MASK) |
|
/* conversion from malloc headers to user pointers, and back */ |
#define chunk2mem(p) ((void*)((char*)(p) + TWO_SIZE_T_SIZES)) |
#define mem2chunk(mem) ((mchunkptr)((char*)(mem) - TWO_SIZE_T_SIZES)) |
/* chunk associated with aligned address A */ |
#define align_as_chunk(A) (mchunkptr)((A) + align_offset(chunk2mem(A))) |
|
/* Bounds on request (not chunk) sizes. */ |
#define MAX_REQUEST ((-MIN_CHUNK_SIZE) << 2) |
#define MIN_REQUEST (MIN_CHUNK_SIZE - CHUNK_OVERHEAD - SIZE_T_ONE) |
|
/* pad request bytes into a usable size */ |
#define pad_request(req) \ |
(((req) + CHUNK_OVERHEAD + CHUNK_ALIGN_MASK) & ~CHUNK_ALIGN_MASK) |
|
/* pad request, checking for minimum (but not maximum) */ |
#define request2size(req) \ |
(((req) < MIN_REQUEST)? MIN_CHUNK_SIZE : pad_request(req)) |
|
|
/* ------------------ Operations on head and foot fields ----------------- */ |
|
/* |
The head field of a chunk is or'ed with PINUSE_BIT when previous |
adjacent chunk in use, and or'ed with CINUSE_BIT if this chunk is in |
use. If the chunk was obtained with mmap, the prev_foot field has |
IS_MMAPPED_BIT set, otherwise holding the offset of the base of the |
mmapped region to the base of the chunk. |
*/ |
|
#define PINUSE_BIT (SIZE_T_ONE) |
#define CINUSE_BIT (SIZE_T_TWO) |
#define INUSE_BITS (PINUSE_BIT|CINUSE_BIT) |
|
/* Head value for fenceposts */ |
#define FENCEPOST_HEAD (INUSE_BITS|SIZE_T_SIZE) |
|
/* extraction of fields from head words */ |
#define cinuse(p) ((p)->head & CINUSE_BIT) |
#define pinuse(p) ((p)->head & PINUSE_BIT) |
#define chunksize(p) ((p)->head & ~(INUSE_BITS)) |
|
#define clear_pinuse(p) ((p)->head &= ~PINUSE_BIT) |
#define clear_cinuse(p) ((p)->head &= ~CINUSE_BIT) |
|
/* Treat space at ptr +/- offset as a chunk */ |
#define chunk_plus_offset(p, s) ((mchunkptr)(((char*)(p)) + (s))) |
#define chunk_minus_offset(p, s) ((mchunkptr)(((char*)(p)) - (s))) |
|
/* Ptr to next or previous physical malloc_chunk. */ |
#define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->head & ~INUSE_BITS))) |
#define prev_chunk(p) ((mchunkptr)( ((char*)(p)) - ((p)->prev_foot) )) |
|
/* extract next chunk's pinuse bit */ |
#define next_pinuse(p) ((next_chunk(p)->head) & PINUSE_BIT) |
|
/* Get/set size at footer */ |
#define get_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_foot) |
#define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_foot = (s)) |
|
/* Set size, pinuse bit, and foot */ |
#define set_size_and_pinuse_of_free_chunk(p, s)\ |
((p)->head = (s|PINUSE_BIT), set_foot(p, s)) |
|
/* Set size, pinuse bit, foot, and clear next pinuse */ |
#define set_free_with_pinuse(p, s, n)\ |
(clear_pinuse(n), set_size_and_pinuse_of_free_chunk(p, s)) |
|
#define is_mmapped(p)\ |
(!((p)->head & PINUSE_BIT) && ((p)->prev_foot & IS_MMAPPED_BIT)) |
|
/* Get the internal overhead associated with chunk p */ |
#define overhead_for(p)\ |
(is_mmapped(p)? MMAP_CHUNK_OVERHEAD : CHUNK_OVERHEAD) |
|
/* Return true if malloced space is not necessarily cleared */ |
#if MMAP_CLEARS |
#define calloc_must_clear(p) (!is_mmapped(p)) |
#else /* MMAP_CLEARS */ |
#define calloc_must_clear(p) (1) |
#endif /* MMAP_CLEARS */ |
|
/* ---------------------- Overlaid data structures ----------------------- */ |
|
/* |
When chunks are not in use, they are treated as nodes of either |
lists or trees. |
|
"Small" chunks are stored in circular doubly-linked lists, and look |
like this: |
|
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Size of previous chunk | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
`head:' | Size of chunk, in bytes |P| |
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Forward pointer to next chunk in list | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Back pointer to previous chunk in list | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Unused space (may be 0 bytes long) . |
. . |
. | |
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
`foot:' | Size of chunk, in bytes | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
|
Larger chunks are kept in a form of bitwise digital trees (aka |
tries) keyed on chunksizes. Because malloc_tree_chunks are only for |
free chunks greater than 256 bytes, their size doesn't impose any |
constraints on user chunk sizes. Each node looks like: |
|
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Size of previous chunk | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
`head:' | Size of chunk, in bytes |P| |
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Forward pointer to next chunk of same size | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Back pointer to previous chunk of same size | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Pointer to left child (child[0]) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Pointer to right child (child[1]) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Pointer to parent | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| bin index of this chunk | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Unused space . |
. | |
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
`foot:' | Size of chunk, in bytes | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
|
Each tree holding treenodes is a tree of unique chunk sizes. Chunks |
of the same size are arranged in a circularly-linked list, with only |
the oldest chunk (the next to be used, in our FIFO ordering) |
actually in the tree. (Tree members are distinguished by a non-null |
parent pointer.) If a chunk with the same size an an existing node |
is inserted, it is linked off the existing node using pointers that |
work in the same way as fd/bk pointers of small chunks. |
|
Each tree contains a power of 2 sized range of chunk sizes (the |
smallest is 0x100 <= x < 0x180), which is is divided in half at each |
tree level, with the chunks in the smaller half of the range (0x100 |
<= x < 0x140 for the top nose) in the left subtree and the larger |
half (0x140 <= x < 0x180) in the right subtree. This is, of course, |
done by inspecting individual bits. |
|
Using these rules, each node's left subtree contains all smaller |
sizes than its right subtree. However, the node at the root of each |
subtree has no particular ordering relationship to either. (The |
dividing line between the subtree sizes is based on trie relation.) |
If we remove the last chunk of a given size from the interior of the |
tree, we need to replace it with a leaf node. The tree ordering |
rules permit a node to be replaced by any leaf below it. |
|
The smallest chunk in a tree (a common operation in a best-fit |
allocator) can be found by walking a path to the leftmost leaf in |
the tree. Unlike a usual binary tree, where we follow left child |
pointers until we reach a null, here we follow the right child |
pointer any time the left one is null, until we reach a leaf with |
both child pointers null. The smallest chunk in the tree will be |
somewhere along that path. |
|
The worst case number of steps to add, find, or remove a node is |
bounded by the number of bits differentiating chunks within |
bins. Under current bin calculations, this ranges from 6 up to 21 |
(for 32 bit sizes) or up to 53 (for 64 bit sizes). The typical case |
is of course much better. |
*/ |
|
struct malloc_tree_chunk { |
/* The first four fields must be compatible with malloc_chunk */ |
size_t prev_foot; |
size_t head; |
struct malloc_tree_chunk* fd; |
struct malloc_tree_chunk* bk; |
|
struct malloc_tree_chunk* child[2]; |
struct malloc_tree_chunk* parent; |
bindex_t index; |
}; |
|
typedef struct malloc_tree_chunk tchunk; |
typedef struct malloc_tree_chunk* tchunkptr; |
typedef struct malloc_tree_chunk* tbinptr; /* The type of bins of trees */ |
|
/* A little helper macro for trees */ |
#define leftmost_child(t) ((t)->child[0] != 0? (t)->child[0] : (t)->child[1]) |
|
/* ----------------------------- Segments -------------------------------- */ |
|
/* |
Each malloc space may include non-contiguous segments, held in a |
list headed by an embedded malloc_segment record representing the |
top-most space. Segments also include flags holding properties of |
the space. Large chunks that are directly allocated by mmap are not |
included in this list. They are instead independently created and |
destroyed without otherwise keeping track of them. |
|
Segment management mainly comes into play for spaces allocated by |
MMAP. Any call to MMAP might or might not return memory that is |
adjacent to an existing segment. MORECORE normally contiguously |
extends the current space, so this space is almost always adjacent, |
which is simpler and faster to deal with. (This is why MORECORE is |
used preferentially to MMAP when both are available -- see |
sys_alloc.) When allocating using MMAP, we don't use any of the |
hinting mechanisms (inconsistently) supported in various |
implementations of unix mmap, or distinguish reserving from |
committing memory. Instead, we just ask for space, and exploit |
contiguity when we get it. It is probably possible to do |
better than this on some systems, but no general scheme seems |
to be significantly better. |
|
Management entails a simpler variant of the consolidation scheme |
used for chunks to reduce fragmentation -- new adjacent memory is |
normally prepended or appended to an existing segment. However, |
there are limitations compared to chunk consolidation that mostly |
reflect the fact that segment processing is relatively infrequent |
(occurring only when getting memory from system) and that we |
don't expect to have huge numbers of segments: |
|
* Segments are not indexed, so traversal requires linear scans. (It |
would be possible to index these, but is not worth the extra |
overhead and complexity for most programs on most platforms.) |
* New segments are only appended to old ones when holding top-most |
memory; if they cannot be prepended to others, they are held in |
different segments. |
|
Except for the top-most segment of an mstate, each segment record |
is kept at the tail of its segment. Segments are added by pushing |
segment records onto the list headed by &mstate.seg for the |
containing mstate. |
|
Segment flags control allocation/merge/deallocation policies: |
* If EXTERN_BIT set, then we did not allocate this segment, |
and so should not try to deallocate or merge with others. |
(This currently holds only for the initial segment passed |
into create_mspace_with_base.) |
* If IS_MMAPPED_BIT set, the segment may be merged with |
other surrounding mmapped segments and trimmed/de-allocated |
using munmap. |
* If neither bit is set, then the segment was obtained using |
MORECORE so can be merged with surrounding MORECORE'd segments |
and deallocated/trimmed using MORECORE with negative arguments. |
*/ |
|
struct malloc_segment { |
char* base; /* base address */ |
size_t size; /* allocated size */ |
struct malloc_segment* next; /* ptr to next segment */ |
flag_t sflags; /* mmap and extern flag */ |
}; |
|
#define is_mmapped_segment(S) ((S)->sflags & IS_MMAPPED_BIT) |
#define is_extern_segment(S) ((S)->sflags & EXTERN_BIT) |
|
typedef struct malloc_segment msegment; |
typedef struct malloc_segment* msegmentptr; |
|
/* ---------------------------- malloc_state ----------------------------- */ |
|
/* |
A malloc_state holds all of the bookkeeping for a space. |
The main fields are: |
|
Top |
The topmost chunk of the currently active segment. Its size is |
cached in topsize. The actual size of topmost space is |
topsize+TOP_FOOT_SIZE, which includes space reserved for adding |
fenceposts and segment records if necessary when getting more |
space from the system. The size at which to autotrim top is |
cached from mparams in trim_check, except that it is disabled if |
an autotrim fails. |
|
Designated victim (dv) |
This is the preferred chunk for servicing small requests that |
don't have exact fits. It is normally the chunk split off most |
recently to service another small request. Its size is cached in |
dvsize. The link fields of this chunk are not maintained since it |
is not kept in a bin. |
|
SmallBins |
An array of bin headers for free chunks. These bins hold chunks |
with sizes less than MIN_LARGE_SIZE bytes. Each bin contains |
chunks of all the same size, spaced 8 bytes apart. To simplify |
use in double-linked lists, each bin header acts as a malloc_chunk |
pointing to the real first node, if it exists (else pointing to |
itself). This avoids special-casing for headers. But to avoid |
waste, we allocate only the fd/bk pointers of bins, and then use |
repositioning tricks to treat these as the fields of a chunk. |
|
TreeBins |
Treebins are pointers to the roots of trees holding a range of |
sizes. There are 2 equally spaced treebins for each power of two |
from TREE_SHIFT to TREE_SHIFT+16. The last bin holds anything |
larger. |
|
Bin maps |
There is one bit map for small bins ("smallmap") and one for |
treebins ("treemap). Each bin sets its bit when non-empty, and |
clears the bit when empty. Bit operations are then used to avoid |
bin-by-bin searching -- nearly all "search" is done without ever |
looking at bins that won't be selected. The bit maps |
conservatively use 32 bits per map word, even if on 64bit system. |
For a good description of some of the bit-based techniques used |
here, see Henry S. Warren Jr's book "Hacker's Delight" (and |
supplement at http://hackersdelight.org/). Many of these are |
intended to reduce the branchiness of paths through malloc etc, as |
well as to reduce the number of memory locations read or written. |
|
Segments |
A list of segments headed by an embedded malloc_segment record |
representing the initial space. |
|
Address check support |
The least_addr field is the least address ever obtained from |
MORECORE or MMAP. Attempted frees and reallocs of any address less |
than this are trapped (unless INSECURE is defined). |
|
Magic tag |
A cross-check field that should always hold same value as mparams.magic. |
|
Flags |
Bits recording whether to use MMAP, locks, or contiguous MORECORE |
|
Statistics |
Each space keeps track of current and maximum system memory |
obtained via MORECORE or MMAP. |
|
Locking |
If USE_LOCKS is defined, the "mutex" lock is acquired and released |
around every public call using this mspace. |
*/ |
|
/* Bin types, widths and sizes */ |
#define NSMALLBINS (32U) |
#define NTREEBINS (32U) |
#define SMALLBIN_SHIFT (3U) |
#define SMALLBIN_WIDTH (SIZE_T_ONE << SMALLBIN_SHIFT) |
#define TREEBIN_SHIFT (8U) |
#define MIN_LARGE_SIZE (SIZE_T_ONE << TREEBIN_SHIFT) |
#define MAX_SMALL_SIZE (MIN_LARGE_SIZE - SIZE_T_ONE) |
#define MAX_SMALL_REQUEST (MAX_SMALL_SIZE - CHUNK_ALIGN_MASK - CHUNK_OVERHEAD) |
|
struct malloc_state { |
binmap_t smallmap; |
binmap_t treemap; |
size_t dvsize; |
size_t topsize; |
char* least_addr; |
mchunkptr dv; |
mchunkptr top; |
size_t trim_check; |
size_t magic; |
mchunkptr smallbins[(NSMALLBINS+1)*2]; |
tbinptr treebins[NTREEBINS]; |
size_t footprint; |
size_t max_footprint; |
flag_t mflags; |
#if USE_LOCKS |
MLOCK_T mutex; /* locate lock among fields that rarely change */ |
#endif /* USE_LOCKS */ |
msegment seg; |
}; |
|
typedef struct malloc_state* mstate; |
|
/* ------------- Global malloc_state and malloc_params ------------------- */ |
|
/* |
malloc_params holds global properties, including those that can be |
dynamically set using mallopt. There is a single instance, mparams, |
initialized in init_mparams. |
*/ |
|
struct malloc_params { |
size_t magic; |
size_t page_size; |
size_t granularity; |
size_t mmap_threshold; |
size_t trim_threshold; |
flag_t default_mflags; |
}; |
|
static struct malloc_params mparams; |
|
/* The global malloc_state used for all non-"mspace" calls */ |
static struct malloc_state _gm_; |
#define gm (&_gm_) |
#define is_global(M) ((M) == &_gm_) |
#define is_initialized(M) ((M)->top != 0) |
|
/* -------------------------- system alloc setup ------------------------- */ |
|
/* Operations on mflags */ |
|
#define use_lock(M) ((M)->mflags & USE_LOCK_BIT) |
#define enable_lock(M) ((M)->mflags |= USE_LOCK_BIT) |
#define disable_lock(M) ((M)->mflags &= ~USE_LOCK_BIT) |
|
#define use_mmap(M) ((M)->mflags & USE_MMAP_BIT) |
#define enable_mmap(M) ((M)->mflags |= USE_MMAP_BIT) |
#define disable_mmap(M) ((M)->mflags &= ~USE_MMAP_BIT) |
|
#define use_noncontiguous(M) ((M)->mflags & USE_NONCONTIGUOUS_BIT) |
#define disable_contiguous(M) ((M)->mflags |= USE_NONCONTIGUOUS_BIT) |
|
#define set_lock(M,L)\ |
((M)->mflags = (L)?\ |
((M)->mflags | USE_LOCK_BIT) :\ |
((M)->mflags & ~USE_LOCK_BIT)) |
|
/* page-align a size */ |
#define page_align(S)\ |
(((S) + (mparams.page_size)) & ~(mparams.page_size - SIZE_T_ONE)) |
|
/* granularity-align a size */ |
#define granularity_align(S)\ |
(((S) + (mparams.granularity)) & ~(mparams.granularity - SIZE_T_ONE)) |
|
#define is_page_aligned(S)\ |
(((size_t)(S) & (mparams.page_size - SIZE_T_ONE)) == 0) |
#define is_granularity_aligned(S)\ |
(((size_t)(S) & (mparams.granularity - SIZE_T_ONE)) == 0) |
|
/* True if segment S holds address A */ |
#define segment_holds(S, A)\ |
((char*)(A) >= S->base && (char*)(A) < S->base + S->size) |
|
/* Return segment holding given address */ |
static msegmentptr segment_holding(mstate m, char* addr) { |
msegmentptr sp = &m->seg; |
for (;;) { |
if (addr >= sp->base && addr < sp->base + sp->size) |
return sp; |
if ((sp = sp->next) == 0) |
return 0; |
} |
} |
|
/* Return true if segment contains a segment link */ |
static int has_segment_link(mstate m, msegmentptr ss) { |
msegmentptr sp = &m->seg; |
for (;;) { |
if ((char*)sp >= ss->base && (char*)sp < ss->base + ss->size) |
return 1; |
if ((sp = sp->next) == 0) |
return 0; |
} |
} |
|
#ifndef MORECORE_CANNOT_TRIM |
#define should_trim(M,s) ((s) > (M)->trim_check) |
#else /* MORECORE_CANNOT_TRIM */ |
#define should_trim(M,s) (0) |
#endif /* MORECORE_CANNOT_TRIM */ |
|
/* |
TOP_FOOT_SIZE is padding at the end of a segment, including space |
that may be needed to place segment records and fenceposts when new |
noncontiguous segments are added. |
*/ |
#define TOP_FOOT_SIZE\ |
(align_offset(chunk2mem(0))+pad_request(sizeof(struct malloc_segment))+MIN_CHUNK_SIZE) |
|
|
/* ------------------------------- Hooks -------------------------------- */ |
|
/* |
PREACTION should be defined to return 0 on success, and nonzero on |
failure. If you are not using locking, you can redefine these to do |
anything you like. |
*/ |
|
#if USE_LOCKS |
|
/* Ensure locks are initialized */ |
#define GLOBALLY_INITIALIZE() (mparams.page_size == 0 && init_mparams()) |
|
#define PREACTION(M) ((GLOBALLY_INITIALIZE() || use_lock(M))? ACQUIRE_LOCK(&(M)->mutex) : 0) |
#define POSTACTION(M) { if (use_lock(M)) RELEASE_LOCK(&(M)->mutex); } |
#else /* USE_LOCKS */ |
|
#ifndef PREACTION |
#define PREACTION(M) (0) |
#endif /* PREACTION */ |
|
#ifndef POSTACTION |
#define POSTACTION(M) |
#endif /* POSTACTION */ |
|
#endif /* USE_LOCKS */ |
|
/* |
CORRUPTION_ERROR_ACTION is triggered upon detected bad addresses. |
USAGE_ERROR_ACTION is triggered on detected bad frees and |
reallocs. The argument p is an address that might have triggered the |
fault. It is ignored by the two predefined actions, but might be |
useful in custom actions that try to help diagnose errors. |
*/ |
|
#if PROCEED_ON_ERROR |
|
/* A count of the number of corruption errors causing resets */ |
int malloc_corruption_error_count; |
|
/* default corruption action */ |
static void reset_on_error(mstate m); |
|
#define CORRUPTION_ERROR_ACTION(m) reset_on_error(m) |
#define USAGE_ERROR_ACTION(m, p) |
|
#else /* PROCEED_ON_ERROR */ |
|
#ifndef CORRUPTION_ERROR_ACTION |
#define CORRUPTION_ERROR_ACTION(m) ABORT |
#endif /* CORRUPTION_ERROR_ACTION */ |
|
#ifndef USAGE_ERROR_ACTION |
#define USAGE_ERROR_ACTION(m,p) ABORT |
#endif /* USAGE_ERROR_ACTION */ |
|
#endif /* PROCEED_ON_ERROR */ |
|
/* -------------------------- Debugging setup ---------------------------- */ |
|
#if ! DEBUG |
|
#define check_free_chunk(M,P) |
#define check_inuse_chunk(M,P) |
#define check_malloced_chunk(M,P,N) |
#define check_mmapped_chunk(M,P) |
#define check_malloc_state(M) |
#define check_top_chunk(M,P) |
|
#else /* DEBUG */ |
#define check_free_chunk(M,P) do_check_free_chunk(M,P) |
#define check_inuse_chunk(M,P) do_check_inuse_chunk(M,P) |
#define check_top_chunk(M,P) do_check_top_chunk(M,P) |
#define check_malloced_chunk(M,P,N) do_check_malloced_chunk(M,P,N) |
#define check_mmapped_chunk(M,P) do_check_mmapped_chunk(M,P) |
#define check_malloc_state(M) do_check_malloc_state(M) |
|
static void do_check_any_chunk(mstate m, mchunkptr p); |
static void do_check_top_chunk(mstate m, mchunkptr p); |
static void do_check_mmapped_chunk(mstate m, mchunkptr p); |
static void do_check_inuse_chunk(mstate m, mchunkptr p); |
static void do_check_free_chunk(mstate m, mchunkptr p); |
static void do_check_malloced_chunk(mstate m, void* mem, size_t s); |
static void do_check_tree(mstate m, tchunkptr t); |
static void do_check_treebin(mstate m, bindex_t i); |
static void do_check_smallbin(mstate m, bindex_t i); |
static void do_check_malloc_state(mstate m); |
static int bin_find(mstate m, mchunkptr x); |
static size_t traverse_and_check(mstate m); |
#endif /* DEBUG */ |
|
/* ---------------------------- Indexing Bins ---------------------------- */ |
|
#define is_small(s) (((s) >> SMALLBIN_SHIFT) < NSMALLBINS) |
#define small_index(s) ((s) >> SMALLBIN_SHIFT) |
#define small_index2size(i) ((i) << SMALLBIN_SHIFT) |
#define MIN_SMALL_INDEX (small_index(MIN_CHUNK_SIZE)) |
|
/* addressing by index. See above about smallbin repositioning */ |
#define smallbin_at(M, i) ((sbinptr)((char*)&((M)->smallbins[(i)<<1]))) |
#define treebin_at(M,i) (&((M)->treebins[i])) |
|
/* assign tree index for size S to variable I */ |
#if defined(__GNUC__) && defined(i386) |
#define compute_tree_index(S, I)\ |
{\ |
size_t X = S >> TREEBIN_SHIFT;\ |
if (X == 0)\ |
I = 0;\ |
else if (X > 0xFFFF)\ |
I = NTREEBINS-1;\ |
else {\ |
unsigned int K;\ |
__asm__("bsrl %1,%0\n\t" : "=r" (K) : "rm" (X));\ |
I = (bindex_t)((K << 1) + ((S >> (K + (TREEBIN_SHIFT-1)) & 1)));\ |
}\ |
} |
#else /* GNUC */ |
#define compute_tree_index(S, I)\ |
{\ |
size_t X = S >> TREEBIN_SHIFT;\ |
if (X == 0)\ |
I = 0;\ |
else if (X > 0xFFFF)\ |
I = NTREEBINS-1;\ |
else {\ |
unsigned int Y = (unsigned int)X;\ |
unsigned int N = ((Y - 0x100) >> 16) & 8;\ |
unsigned int K = (((Y <<= N) - 0x1000) >> 16) & 4;\ |
N += K;\ |
N += K = (((Y <<= K) - 0x4000) >> 16) & 2;\ |
K = 14 - N + ((Y <<= K) >> 15);\ |
I = (K << 1) + ((S >> (K + (TREEBIN_SHIFT-1)) & 1));\ |
}\ |
} |
#endif /* GNUC */ |
|
/* Bit representing maximum resolved size in a treebin at i */ |
#define bit_for_tree_index(i) \ |
(i == NTREEBINS-1)? (SIZE_T_BITSIZE-1) : (((i) >> 1) + TREEBIN_SHIFT - 2) |
|
/* Shift placing maximum resolved bit in a treebin at i as sign bit */ |
#define leftshift_for_tree_index(i) \ |
((i == NTREEBINS-1)? 0 : \ |
((SIZE_T_BITSIZE-SIZE_T_ONE) - (((i) >> 1) + TREEBIN_SHIFT - 2))) |
|
/* The size of the smallest chunk held in bin with index i */ |
#define minsize_for_tree_index(i) \ |
((SIZE_T_ONE << (((i) >> 1) + TREEBIN_SHIFT)) | \ |
(((size_t)((i) & SIZE_T_ONE)) << (((i) >> 1) + TREEBIN_SHIFT - 1))) |
|
|
/* ------------------------ Operations on bin maps ----------------------- */ |
|
/* bit corresponding to given index */ |
#define idx2bit(i) ((binmap_t)(1) << (i)) |
|
/* Mark/Clear bits with given index */ |
#define mark_smallmap(M,i) ((M)->smallmap |= idx2bit(i)) |
#define clear_smallmap(M,i) ((M)->smallmap &= ~idx2bit(i)) |
#define smallmap_is_marked(M,i) ((M)->smallmap & idx2bit(i)) |
|
#define mark_treemap(M,i) ((M)->treemap |= idx2bit(i)) |
#define clear_treemap(M,i) ((M)->treemap &= ~idx2bit(i)) |
#define treemap_is_marked(M,i) ((M)->treemap & idx2bit(i)) |
|
/* index corresponding to given bit */ |
|
#if defined(__GNUC__) && defined(i386) |
#define compute_bit2idx(X, I)\ |
{\ |
unsigned int J;\ |
__asm__("bsfl %1,%0\n\t" : "=r" (J) : "rm" (X));\ |
I = (bindex_t)J;\ |
} |
|
#else /* GNUC */ |
#if USE_BUILTIN_FFS |
#define compute_bit2idx(X, I) I = ffs(X)-1 |
|
#else /* USE_BUILTIN_FFS */ |
#define compute_bit2idx(X, I)\ |
{\ |
unsigned int Y = X - 1;\ |
unsigned int K = Y >> (16-4) & 16;\ |
unsigned int N = K; Y >>= K;\ |
N += K = Y >> (8-3) & 8; Y >>= K;\ |
N += K = Y >> (4-2) & 4; Y >>= K;\ |
N += K = Y >> (2-1) & 2; Y >>= K;\ |
N += K = Y >> (1-0) & 1; Y >>= K;\ |
I = (bindex_t)(N + Y);\ |
} |
#endif /* USE_BUILTIN_FFS */ |
#endif /* GNUC */ |
|
/* isolate the least set bit of a bitmap */ |
#define least_bit(x) ((x) & -(x)) |
|
/* mask with all bits to left of least bit of x on */ |
#define left_bits(x) ((x<<1) | -(x<<1)) |
|
/* mask with all bits to left of or equal to least bit of x on */ |
#define same_or_left_bits(x) ((x) | -(x)) |
|
|
/* ----------------------- Runtime Check Support ------------------------- */ |
|
/* |
For security, the main invariant is that malloc/free/etc never |
writes to a static address other than malloc_state, unless static |
malloc_state itself has been corrupted, which cannot occur via |
malloc (because of these checks). In essence this means that we |
believe all pointers, sizes, maps etc held in malloc_state, but |
check all of those linked or offsetted from other embedded data |
structures. These checks are interspersed with main code in a way |
that tends to minimize their run-time cost. |
|
When FOOTERS is defined, in addition to range checking, we also |
verify footer fields of inuse chunks, which can be used guarantee |
that the mstate controlling malloc/free is intact. This is a |
streamlined version of the approach described by William Robertson |
et al in "Run-time Detection of Heap-based Overflows" LISA'03 |
http://www.usenix.org/events/lisa03/tech/robertson.html The footer |
of an inuse chunk holds the xor of its mstate and a random seed, |
that is checked upon calls to free() and realloc(). This is |
(probablistically) unguessable from outside the program, but can be |
computed by any code successfully malloc'ing any chunk, so does not |
itself provide protection against code that has already broken |
security through some other means. Unlike Robertson et al, we |
always dynamically check addresses of all offset chunks (previous, |
next, etc). This turns out to be cheaper than relying on hashes. |
*/ |
|
#if !INSECURE |
/* Check if address a is at least as high as any from MORECORE or MMAP */ |
#define ok_address(M, a) ((char*)(a) >= (M)->least_addr) |
/* Check if address of next chunk n is higher than base chunk p */ |
#define ok_next(p, n) ((char*)(p) < (char*)(n)) |
/* Check if p has its cinuse bit on */ |
#define ok_cinuse(p) cinuse(p) |
/* Check if p has its pinuse bit on */ |
#define ok_pinuse(p) pinuse(p) |
|
#else /* !INSECURE */ |
#define ok_address(M, a) (1) |
#define ok_next(b, n) (1) |
#define ok_cinuse(p) (1) |
#define ok_pinuse(p) (1) |
#endif /* !INSECURE */ |
|
#if (FOOTERS && !INSECURE) |
/* Check if (alleged) mstate m has expected magic field */ |
#define ok_magic(M) ((M)->magic == mparams.magic) |
#else /* (FOOTERS && !INSECURE) */ |
#define ok_magic(M) (1) |
#endif /* (FOOTERS && !INSECURE) */ |
|
|
/* In gcc, use __builtin_expect to minimize impact of checks */ |
#if !INSECURE |
#if defined(__GNUC__) && __GNUC__ >= 3 |
#define RTCHECK(e) __builtin_expect(e, 1) |
#else /* GNUC */ |
#define RTCHECK(e) (e) |
#endif /* GNUC */ |
#else /* !INSECURE */ |
#define RTCHECK(e) (1) |
#endif /* !INSECURE */ |
|
/* macros to set up inuse chunks with or without footers */ |
|
#if !FOOTERS |
|
#define mark_inuse_foot(M,p,s) |
|
/* Set cinuse bit and pinuse bit of next chunk */ |
#define set_inuse(M,p,s)\ |
((p)->head = (((p)->head & PINUSE_BIT)|s|CINUSE_BIT),\ |
((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT) |
|
/* Set cinuse and pinuse of this chunk and pinuse of next chunk */ |
#define set_inuse_and_pinuse(M,p,s)\ |
((p)->head = (s|PINUSE_BIT|CINUSE_BIT),\ |
((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT) |
|
/* Set size, cinuse and pinuse bit of this chunk */ |
#define set_size_and_pinuse_of_inuse_chunk(M, p, s)\ |
((p)->head = (s|PINUSE_BIT|CINUSE_BIT)) |
|
#else /* FOOTERS */ |
|
/* Set foot of inuse chunk to be xor of mstate and seed */ |
#define mark_inuse_foot(M,p,s)\ |
(((mchunkptr)((char*)(p) + (s)))->prev_foot = ((size_t)(M) ^ mparams.magic)) |
|
#define get_mstate_for(p)\ |
((mstate)(((mchunkptr)((char*)(p) +\ |
(chunksize(p))))->prev_foot ^ mparams.magic)) |
|
#define set_inuse(M,p,s)\ |
((p)->head = (((p)->head & PINUSE_BIT)|s|CINUSE_BIT),\ |
(((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT), \ |
mark_inuse_foot(M,p,s)) |
|
#define set_inuse_and_pinuse(M,p,s)\ |
((p)->head = (s|PINUSE_BIT|CINUSE_BIT),\ |
(((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT),\ |
mark_inuse_foot(M,p,s)) |
|
#define set_size_and_pinuse_of_inuse_chunk(M, p, s)\ |
((p)->head = (s|PINUSE_BIT|CINUSE_BIT),\ |
mark_inuse_foot(M, p, s)) |
|
#endif /* !FOOTERS */ |
|
/* ---------------------------- setting mparams -------------------------- */ |
|
/* Initialize mparams */ |
static int init_mparams(void) { |
if (mparams.page_size == 0) { |
size_t s; |
|
mparams.mmap_threshold = DEFAULT_MMAP_THRESHOLD; |
mparams.trim_threshold = DEFAULT_TRIM_THRESHOLD; |
#if MORECORE_CONTIGUOUS |
mparams.default_mflags = USE_LOCK_BIT|USE_MMAP_BIT; |
#else /* MORECORE_CONTIGUOUS */ |
mparams.default_mflags = USE_LOCK_BIT|USE_MMAP_BIT|USE_NONCONTIGUOUS_BIT; |
#endif /* MORECORE_CONTIGUOUS */ |
|
#if (FOOTERS && !INSECURE) |
{ |
#if USE_DEV_RANDOM |
int fd; |
unsigned char buf[sizeof(size_t)]; |
/* Try to use /dev/urandom, else fall back on using time */ |
if ((fd = open("/dev/urandom", O_RDONLY)) >= 0 && |
read(fd, buf, sizeof(buf)) == sizeof(buf)) { |
s = *((size_t *) buf); |
close(fd); |
} |
else |
#endif /* USE_DEV_RANDOM */ |
s = (size_t)(time(0) ^ (size_t)0x55555555U); |
|
s |= (size_t)8U; /* ensure nonzero */ |
s &= ~(size_t)7U; /* improve chances of fault for bad values */ |
|
} |
#else /* (FOOTERS && !INSECURE) */ |
s = (size_t)0x58585858U; |
#endif /* (FOOTERS && !INSECURE) */ |
ACQUIRE_MAGIC_INIT_LOCK(); |
if (mparams.magic == 0) { |
mparams.magic = s; |
/* Set up lock for main malloc area */ |
INITIAL_LOCK(&gm->mutex); |
gm->mflags = mparams.default_mflags; |
} |
RELEASE_MAGIC_INIT_LOCK(); |
|
#ifndef WIN32 |
mparams.page_size = malloc_getpagesize; |
mparams.granularity = ((DEFAULT_GRANULARITY != 0)? |
DEFAULT_GRANULARITY : mparams.page_size); |
#else /* WIN32 */ |
{ |
SYSTEM_INFO system_info; |
GetSystemInfo(&system_info); |
mparams.page_size = system_info.dwPageSize; |
mparams.granularity = system_info.dwAllocationGranularity; |
} |
#endif /* WIN32 */ |
|
/* Sanity-check configuration: |
size_t must be unsigned and as wide as pointer type. |
ints must be at least 4 bytes. |
alignment must be at least 8. |
Alignment, min chunk size, and page size must all be powers of 2. |
*/ |
if ((sizeof(size_t) != sizeof(char*)) || |
(MAX_SIZE_T < MIN_CHUNK_SIZE) || |
(sizeof(int) < 4) || |
(MALLOC_ALIGNMENT < (size_t)8U) || |
((MALLOC_ALIGNMENT & (MALLOC_ALIGNMENT-SIZE_T_ONE)) != 0) || |
((MCHUNK_SIZE & (MCHUNK_SIZE-SIZE_T_ONE)) != 0) || |
((mparams.granularity & (mparams.granularity-SIZE_T_ONE)) != 0) || |
((mparams.page_size & (mparams.page_size-SIZE_T_ONE)) != 0)) |
ABORT; |
} |
return 0; |
} |
|
/* support for mallopt */ |
static int change_mparam(int param_number, int value) { |
size_t val = (size_t)value; |
init_mparams(); |
switch(param_number) { |
case M_TRIM_THRESHOLD: |
mparams.trim_threshold = val; |
return 1; |
case M_GRANULARITY: |
if (val >= mparams.page_size && ((val & (val-1)) == 0)) { |
mparams.granularity = val; |
return 1; |
} |
else |
return 0; |
case M_MMAP_THRESHOLD: |
mparams.mmap_threshold = val; |
return 1; |
default: |
return 0; |
} |
} |
|
#if DEBUG |
/* ------------------------- Debugging Support --------------------------- */ |
|
/* Check properties of any chunk, whether free, inuse, mmapped etc */ |
static void do_check_any_chunk(mstate m, mchunkptr p) { |
assert((is_aligned(chunk2mem(p))) || (p->head == FENCEPOST_HEAD)); |
assert(ok_address(m, p)); |
} |
|
/* Check properties of top chunk */ |
static void do_check_top_chunk(mstate m, mchunkptr p) { |
msegmentptr sp = segment_holding(m, (char*)p); |
size_t sz = chunksize(p); |
assert(sp != 0); |
assert((is_aligned(chunk2mem(p))) || (p->head == FENCEPOST_HEAD)); |
assert(ok_address(m, p)); |
assert(sz == m->topsize); |
assert(sz > 0); |
assert(sz == ((sp->base + sp->size) - (char*)p) - TOP_FOOT_SIZE); |
assert(pinuse(p)); |
assert(!next_pinuse(p)); |
} |
|
/* Check properties of (inuse) mmapped chunks */ |
static void do_check_mmapped_chunk(mstate m, mchunkptr p) { |
size_t sz = chunksize(p); |
size_t len = (sz + (p->prev_foot & ~IS_MMAPPED_BIT) + MMAP_FOOT_PAD); |
assert(is_mmapped(p)); |
assert(use_mmap(m)); |
assert((is_aligned(chunk2mem(p))) || (p->head == FENCEPOST_HEAD)); |
assert(ok_address(m, p)); |
assert(!is_small(sz)); |
assert((len & (mparams.page_size-SIZE_T_ONE)) == 0); |
assert(chunk_plus_offset(p, sz)->head == FENCEPOST_HEAD); |
assert(chunk_plus_offset(p, sz+SIZE_T_SIZE)->head == 0); |
} |
|
/* Check properties of inuse chunks */ |
static void do_check_inuse_chunk(mstate m, mchunkptr p) { |
do_check_any_chunk(m, p); |
assert(cinuse(p)); |
assert(next_pinuse(p)); |
/* If not pinuse and not mmapped, previous chunk has OK offset */ |
assert(is_mmapped(p) || pinuse(p) || next_chunk(prev_chunk(p)) == p); |
if (is_mmapped(p)) |
do_check_mmapped_chunk(m, p); |
} |
|
/* Check properties of free chunks */ |
static void do_check_free_chunk(mstate m, mchunkptr p) { |
size_t sz = p->head & ~(PINUSE_BIT|CINUSE_BIT); |
mchunkptr next = chunk_plus_offset(p, sz); |
do_check_any_chunk(m, p); |
assert(!cinuse(p)); |
assert(!next_pinuse(p)); |
assert (!is_mmapped(p)); |
if (p != m->dv && p != m->top) { |
if (sz >= MIN_CHUNK_SIZE) { |
assert((sz & CHUNK_ALIGN_MASK) == 0); |
assert(is_aligned(chunk2mem(p))); |
assert(next->prev_foot == sz); |
assert(pinuse(p)); |
assert (next == m->top || cinuse(next)); |
assert(p->fd->bk == p); |
assert(p->bk->fd == p); |
} |
else /* markers are always of size SIZE_T_SIZE */ |
assert(sz == SIZE_T_SIZE); |
} |
} |
|
/* Check properties of malloced chunks at the point they are malloced */ |
static void do_check_malloced_chunk(mstate m, void* mem, size_t s) { |
if (mem != 0) { |
mchunkptr p = mem2chunk(mem); |
size_t sz = p->head & ~(PINUSE_BIT|CINUSE_BIT); |
do_check_inuse_chunk(m, p); |
assert((sz & CHUNK_ALIGN_MASK) == 0); |
assert(sz >= MIN_CHUNK_SIZE); |
assert(sz >= s); |
/* unless mmapped, size is less than MIN_CHUNK_SIZE more than request */ |
assert(is_mmapped(p) || sz < (s + MIN_CHUNK_SIZE)); |
} |
} |
|
/* Check a tree and its subtrees. */ |
static void do_check_tree(mstate m, tchunkptr t) { |
tchunkptr head = 0; |
tchunkptr u = t; |
bindex_t tindex = t->index; |
size_t tsize = chunksize(t); |
bindex_t idx; |
compute_tree_index(tsize, idx); |
assert(tindex == idx); |
assert(tsize >= MIN_LARGE_SIZE); |
assert(tsize >= minsize_for_tree_index(idx)); |
assert((idx == NTREEBINS-1) || (tsize < minsize_for_tree_index((idx+1)))); |
|
do { /* traverse through chain of same-sized nodes */ |
do_check_any_chunk(m, ((mchunkptr)u)); |
assert(u->index == tindex); |
assert(chunksize(u) == tsize); |
assert(!cinuse(u)); |
assert(!next_pinuse(u)); |
assert(u->fd->bk == u); |
assert(u->bk->fd == u); |
if (u->parent == 0) { |
assert(u->child[0] == 0); |
assert(u->child[1] == 0); |
} |
else { |
assert(head == 0); /* only one node on chain has parent */ |
head = u; |
assert(u->parent != u); |
assert (u->parent->child[0] == u || |
u->parent->child[1] == u || |
*((tbinptr*)(u->parent)) == u); |
if (u->child[0] != 0) { |
assert(u->child[0]->parent == u); |
assert(u->child[0] != u); |
do_check_tree(m, u->child[0]); |
} |
if (u->child[1] != 0) { |
assert(u->child[1]->parent == u); |
assert(u->child[1] != u); |
do_check_tree(m, u->child[1]); |
} |
if (u->child[0] != 0 && u->child[1] != 0) { |
assert(chunksize(u->child[0]) < chunksize(u->child[1])); |
} |
} |
u = u->fd; |
} while (u != t); |
assert(head != 0); |
} |
|
/* Check all the chunks in a treebin. */ |
static void do_check_treebin(mstate m, bindex_t i) { |
tbinptr* tb = treebin_at(m, i); |
tchunkptr t = *tb; |
int empty = (m->treemap & (1U << i)) == 0; |
if (t == 0) |
assert(empty); |
if (!empty) |
do_check_tree(m, t); |
} |
|
/* Check all the chunks in a smallbin. */ |
static void do_check_smallbin(mstate m, bindex_t i) { |
sbinptr b = smallbin_at(m, i); |
mchunkptr p = b->bk; |
unsigned int empty = (m->smallmap & (1U << i)) == 0; |
if (p == b) |
assert(empty); |
if (!empty) { |
for (; p != b; p = p->bk) { |
size_t size = chunksize(p); |
mchunkptr q; |
/* each chunk claims to be free */ |
do_check_free_chunk(m, p); |
/* chunk belongs in bin */ |
assert(small_index(size) == i); |
assert(p->bk == b || chunksize(p->bk) == chunksize(p)); |
/* chunk is followed by an inuse chunk */ |
q = next_chunk(p); |
if (q->head != FENCEPOST_HEAD) |
do_check_inuse_chunk(m, q); |
} |
} |
} |
|
/* Find x in a bin. Used in other check functions. */ |
static int bin_find(mstate m, mchunkptr x) { |
size_t size = chunksize(x); |
if (is_small(size)) { |
bindex_t sidx = small_index(size); |
sbinptr b = smallbin_at(m, sidx); |
if (smallmap_is_marked(m, sidx)) { |
mchunkptr p = b; |
do { |
if (p == x) |
return 1; |
} while ((p = p->fd) != b); |
} |
} |
else { |
bindex_t tidx; |
compute_tree_index(size, tidx); |
if (treemap_is_marked(m, tidx)) { |
tchunkptr t = *treebin_at(m, tidx); |
size_t sizebits = size << leftshift_for_tree_index(tidx); |
while (t != 0 && chunksize(t) != size) { |
t = t->child[(sizebits >> (SIZE_T_BITSIZE-SIZE_T_ONE)) & 1]; |
sizebits <<= 1; |
} |
if (t != 0) { |
tchunkptr u = t; |
do { |
if (u == (tchunkptr)x) |
return 1; |
} while ((u = u->fd) != t); |
} |
} |
} |
return 0; |
} |
|
/* Traverse each chunk and check it; return total */ |
static size_t traverse_and_check(mstate m) { |
size_t sum = 0; |
if (is_initialized(m)) { |
msegmentptr s = &m->seg; |
sum += m->topsize + TOP_FOOT_SIZE; |
while (s != 0) { |
mchunkptr q = align_as_chunk(s->base); |
mchunkptr lastq = 0; |
assert(pinuse(q)); |
while (segment_holds(s, q) && |
q != m->top && q->head != FENCEPOST_HEAD) { |
sum += chunksize(q); |
if (cinuse(q)) { |
assert(!bin_find(m, q)); |
do_check_inuse_chunk(m, q); |
} |
else { |
assert(q == m->dv || bin_find(m, q)); |
assert(lastq == 0 || cinuse(lastq)); /* Not 2 consecutive free */ |
do_check_free_chunk(m, q); |
} |
lastq = q; |
q = next_chunk(q); |
} |
s = s->next; |
} |
} |
return sum; |
} |
|
/* Check all properties of malloc_state. */ |
static void do_check_malloc_state(mstate m) { |
bindex_t i; |
size_t total; |
/* check bins */ |
for (i = 0; i < NSMALLBINS; ++i) |
do_check_smallbin(m, i); |
for (i = 0; i < NTREEBINS; ++i) |
do_check_treebin(m, i); |
|
if (m->dvsize != 0) { /* check dv chunk */ |
do_check_any_chunk(m, m->dv); |
assert(m->dvsize == chunksize(m->dv)); |
assert(m->dvsize >= MIN_CHUNK_SIZE); |
assert(bin_find(m, m->dv) == 0); |
} |
|
if (m->top != 0) { /* check top chunk */ |
do_check_top_chunk(m, m->top); |
assert(m->topsize == chunksize(m->top)); |
assert(m->topsize > 0); |
assert(bin_find(m, m->top) == 0); |
} |
|
total = traverse_and_check(m); |
assert(total <= m->footprint); |
assert(m->footprint <= m->max_footprint); |
} |
#endif /* DEBUG */ |
|
/* ----------------------------- statistics ------------------------------ */ |
|
#if !NO_MALLINFO |
static struct mallinfo internal_mallinfo(mstate m) { |
struct mallinfo nm = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; |
if (!PREACTION(m)) { |
check_malloc_state(m); |
if (is_initialized(m)) { |
size_t nfree = SIZE_T_ONE; /* top always free */ |
size_t mfree = m->topsize + TOP_FOOT_SIZE; |
size_t sum = mfree; |
msegmentptr s = &m->seg; |
while (s != 0) { |
mchunkptr q = align_as_chunk(s->base); |
while (segment_holds(s, q) && |
q != m->top && q->head != FENCEPOST_HEAD) { |
size_t sz = chunksize(q); |
sum += sz; |
if (!cinuse(q)) { |
mfree += sz; |
++nfree; |
} |
q = next_chunk(q); |
} |
s = s->next; |
} |
|
nm.arena = sum; |
nm.ordblks = nfree; |
nm.hblkhd = m->footprint - sum; |
nm.usmblks = m->max_footprint; |
nm.uordblks = m->footprint - mfree; |
nm.fordblks = mfree; |
nm.keepcost = m->topsize; |
} |
|
POSTACTION(m); |
} |
return nm; |
} |
#endif /* !NO_MALLINFO */ |
|
static void internal_malloc_stats(mstate m) { |
if (!PREACTION(m)) { |
size_t maxfp = 0; |
size_t fp = 0; |
size_t used = 0; |
check_malloc_state(m); |
if (is_initialized(m)) { |
msegmentptr s = &m->seg; |
maxfp = m->max_footprint; |
fp = m->footprint; |
used = fp - (m->topsize + TOP_FOOT_SIZE); |
|
while (s != 0) { |
mchunkptr q = align_as_chunk(s->base); |
while (segment_holds(s, q) && |
q != m->top && q->head != FENCEPOST_HEAD) { |
if (!cinuse(q)) |
used -= chunksize(q); |
q = next_chunk(q); |
} |
s = s->next; |
} |
} |
|
fprintf(stderr, "max system bytes = %10lu\n", (unsigned long)(maxfp)); |
fprintf(stderr, "system bytes = %10lu\n", (unsigned long)(fp)); |
fprintf(stderr, "in use bytes = %10lu\n", (unsigned long)(used)); |
|
POSTACTION(m); |
} |
} |
|
/* ----------------------- Operations on smallbins ----------------------- */ |
|
/* |
Various forms of linking and unlinking are defined as macros. Even |
the ones for trees, which are very long but have very short typical |
paths. This is ugly but reduces reliance on inlining support of |
compilers. |
*/ |
|
/* Link a free chunk into a smallbin */ |
#define insert_small_chunk(M, P, S) {\ |
bindex_t I = small_index(S);\ |
mchunkptr B = smallbin_at(M, I);\ |
mchunkptr F = B;\ |
assert(S >= MIN_CHUNK_SIZE);\ |
if (!smallmap_is_marked(M, I))\ |
mark_smallmap(M, I);\ |
else if (RTCHECK(ok_address(M, B->fd)))\ |
F = B->fd;\ |
else {\ |
CORRUPTION_ERROR_ACTION(M);\ |
}\ |
B->fd = P;\ |
F->bk = P;\ |
P->fd = F;\ |
P->bk = B;\ |
} |
|
/* Unlink a chunk from a smallbin */ |
#define unlink_small_chunk(M, P, S) {\ |
mchunkptr F = P->fd;\ |
mchunkptr B = P->bk;\ |
bindex_t I = small_index(S);\ |
assert(P != B);\ |
assert(P != F);\ |
assert(chunksize(P) == small_index2size(I));\ |
if (F == B)\ |
clear_smallmap(M, I);\ |
else if (RTCHECK((F == smallbin_at(M,I) || ok_address(M, F)) &&\ |
(B == smallbin_at(M,I) || ok_address(M, B)))) {\ |
F->bk = B;\ |
B->fd = F;\ |
}\ |
else {\ |
CORRUPTION_ERROR_ACTION(M);\ |
}\ |
} |
|
/* Unlink the first chunk from a smallbin */ |
#define unlink_first_small_chunk(M, B, P, I) {\ |
mchunkptr F = P->fd;\ |
assert(P != B);\ |
assert(P != F);\ |
assert(chunksize(P) == small_index2size(I));\ |
if (B == F)\ |
clear_smallmap(M, I);\ |
else if (RTCHECK(ok_address(M, F))) {\ |
B->fd = F;\ |
F->bk = B;\ |
}\ |
else {\ |
CORRUPTION_ERROR_ACTION(M);\ |
}\ |
} |
|
/* Replace dv node, binning the old one */ |
/* Used only when dvsize known to be small */ |
#define replace_dv(M, P, S) {\ |
size_t DVS = M->dvsize;\ |
if (DVS != 0) {\ |
mchunkptr DV = M->dv;\ |
assert(is_small(DVS));\ |
insert_small_chunk(M, DV, DVS);\ |
}\ |
M->dvsize = S;\ |
M->dv = P;\ |
} |
|
/* ------------------------- Operations on trees ------------------------- */ |
|
/* Insert chunk into tree */ |
#define insert_large_chunk(M, X, S) {\ |
tbinptr* H;\ |
bindex_t I;\ |
compute_tree_index(S, I);\ |
H = treebin_at(M, I);\ |
X->index = I;\ |
X->child[0] = X->child[1] = 0;\ |
if (!treemap_is_marked(M, I)) {\ |
mark_treemap(M, I);\ |
*H = X;\ |
X->parent = (tchunkptr)H;\ |
X->fd = X->bk = X;\ |
}\ |
else {\ |
tchunkptr T = *H;\ |
size_t K = S << leftshift_for_tree_index(I);\ |
for (;;) {\ |
if (chunksize(T) != S) {\ |
tchunkptr* C = &(T->child[(K >> (SIZE_T_BITSIZE-SIZE_T_ONE)) & 1]);\ |
K <<= 1;\ |
if (*C != 0)\ |
T = *C;\ |
else if (RTCHECK(ok_address(M, C))) {\ |
*C = X;\ |
X->parent = T;\ |
X->fd = X->bk = X;\ |
break;\ |
}\ |
else {\ |
CORRUPTION_ERROR_ACTION(M);\ |
break;\ |
}\ |
}\ |
else {\ |
tchunkptr F = T->fd;\ |
if (RTCHECK(ok_address(M, T) && ok_address(M, F))) {\ |
T->fd = F->bk = X;\ |
X->fd = F;\ |
X->bk = T;\ |
X->parent = 0;\ |
break;\ |
}\ |
else {\ |
CORRUPTION_ERROR_ACTION(M);\ |
break;\ |
}\ |
}\ |
}\ |
}\ |
} |
|
/* |
Unlink steps: |
|
1. If x is a chained node, unlink it from its same-sized fd/bk links |
and choose its bk node as its replacement. |
2. If x was the last node of its size, but not a leaf node, it must |
be replaced with a leaf node (not merely one with an open left or |
right), to make sure that lefts and rights of descendents |
correspond properly to bit masks. We use the rightmost descendent |
of x. We could use any other leaf, but this is easy to locate and |
tends to counteract removal of leftmosts elsewhere, and so keeps |
paths shorter than minimally guaranteed. This doesn't loop much |
because on average a node in a tree is near the bottom. |
3. If x is the base of a chain (i.e., has parent links) relink |
x's parent and children to x's replacement (or null if none). |
*/ |
|
#define unlink_large_chunk(M, X) {\ |
tchunkptr XP = X->parent;\ |
tchunkptr R;\ |
if (X->bk != X) {\ |
tchunkptr F = X->fd;\ |
R = X->bk;\ |
if (RTCHECK(ok_address(M, F))) {\ |
F->bk = R;\ |
R->fd = F;\ |
}\ |
else {\ |
CORRUPTION_ERROR_ACTION(M);\ |
}\ |
}\ |
else {\ |
tchunkptr* RP;\ |
if (((R = *(RP = &(X->child[1]))) != 0) ||\ |
((R = *(RP = &(X->child[0]))) != 0)) {\ |
tchunkptr* CP;\ |
while ((*(CP = &(R->child[1])) != 0) ||\ |
(*(CP = &(R->child[0])) != 0)) {\ |
R = *(RP = CP);\ |
}\ |
if (RTCHECK(ok_address(M, RP)))\ |
*RP = 0;\ |
else {\ |
CORRUPTION_ERROR_ACTION(M);\ |
}\ |
}\ |
}\ |
if (XP != 0) {\ |
tbinptr* H = treebin_at(M, X->index);\ |
if (X == *H) {\ |
if ((*H = R) == 0) \ |
clear_treemap(M, X->index);\ |
}\ |
else if (RTCHECK(ok_address(M, XP))) {\ |
if (XP->child[0] == X) \ |
XP->child[0] = R;\ |
else \ |
XP->child[1] = R;\ |
}\ |
else\ |
CORRUPTION_ERROR_ACTION(M);\ |
if (R != 0) {\ |
if (RTCHECK(ok_address(M, R))) {\ |
tchunkptr C0, C1;\ |
R->parent = XP;\ |
if ((C0 = X->child[0]) != 0) {\ |
if (RTCHECK(ok_address(M, C0))) {\ |
R->child[0] = C0;\ |
C0->parent = R;\ |
}\ |
else\ |
CORRUPTION_ERROR_ACTION(M);\ |
}\ |
if ((C1 = X->child[1]) != 0) {\ |
if (RTCHECK(ok_address(M, C1))) {\ |
R->child[1] = C1;\ |
C1->parent = R;\ |
}\ |
else\ |
CORRUPTION_ERROR_ACTION(M);\ |
}\ |
}\ |
else\ |
CORRUPTION_ERROR_ACTION(M);\ |
}\ |
}\ |
} |
|
/* Relays to large vs small bin operations */ |
|
#define insert_chunk(M, P, S)\ |
if (is_small(S)) insert_small_chunk(M, P, S)\ |
else { tchunkptr TP = (tchunkptr)(P); insert_large_chunk(M, TP, S); } |
|
#define unlink_chunk(M, P, S)\ |
if (is_small(S)) unlink_small_chunk(M, P, S)\ |
else { tchunkptr TP = (tchunkptr)(P); unlink_large_chunk(M, TP); } |
|
|
/* Relays to internal calls to malloc/free from realloc, memalign etc */ |
|
#if ONLY_MSPACES |
#define internal_malloc(m, b) mspace_malloc(m, b) |
#define internal_free(m, mem) mspace_free(m,mem); |
#else /* ONLY_MSPACES */ |
#if MSPACES |
#define internal_malloc(m, b)\ |
(m == gm)? dlmalloc(b) : mspace_malloc(m, b) |
#define internal_free(m, mem)\ |
if (m == gm) dlfree(mem); else mspace_free(m,mem); |
#else /* MSPACES */ |
#define internal_malloc(m, b) dlmalloc(b) |
#define internal_free(m, mem) dlfree(mem) |
#endif /* MSPACES */ |
#endif /* ONLY_MSPACES */ |
|
/* ----------------------- Direct-mmapping chunks ----------------------- */ |
|
/* |
Directly mmapped chunks are set up with an offset to the start of |
the mmapped region stored in the prev_foot field of the chunk. This |
allows reconstruction of the required argument to MUNMAP when freed, |
and also allows adjustment of the returned chunk to meet alignment |
requirements (especially in memalign). There is also enough space |
allocated to hold a fake next chunk of size SIZE_T_SIZE to maintain |
the PINUSE bit so frees can be checked. |
*/ |
|
/* Malloc using mmap */ |
static void* mmap_alloc(mstate m, size_t nb) { |
size_t mmsize = granularity_align(nb + SIX_SIZE_T_SIZES + CHUNK_ALIGN_MASK); |
if (mmsize > nb) { /* Check for wrap around 0 */ |
char* mm = (char*)(DIRECT_MMAP(mmsize)); |
if (mm != CMFAIL) { |
size_t offset = align_offset(chunk2mem(mm)); |
size_t psize = mmsize - offset - MMAP_FOOT_PAD; |
mchunkptr p = (mchunkptr)(mm + offset); |
p->prev_foot = offset | IS_MMAPPED_BIT; |
(p)->head = (psize|CINUSE_BIT); |
mark_inuse_foot(m, p, psize); |
chunk_plus_offset(p, psize)->head = FENCEPOST_HEAD; |
chunk_plus_offset(p, psize+SIZE_T_SIZE)->head = 0; |
|
if (mm < m->least_addr) |
m->least_addr = mm; |
if ((m->footprint += mmsize) > m->max_footprint) |
m->max_footprint = m->footprint; |
assert(is_aligned(chunk2mem(p))); |
check_mmapped_chunk(m, p); |
return chunk2mem(p); |
} |
} |
return 0; |
} |
|
/* Realloc using mmap */ |
static mchunkptr mmap_resize(mstate m, mchunkptr oldp, size_t nb) { |
size_t oldsize = chunksize(oldp); |
if (is_small(nb)) /* Can't shrink mmap regions below small size */ |
return 0; |
/* Keep old chunk if big enough but not too big */ |
if (oldsize >= nb + SIZE_T_SIZE && |
(oldsize - nb) <= (mparams.granularity << 1)) |
return oldp; |
else { |
size_t offset = oldp->prev_foot & ~IS_MMAPPED_BIT; |
size_t oldmmsize = oldsize + offset + MMAP_FOOT_PAD; |
size_t newmmsize = granularity_align(nb + SIX_SIZE_T_SIZES + |
CHUNK_ALIGN_MASK); |
char* cp = (char*)CALL_MREMAP((char*)oldp - offset, |
oldmmsize, newmmsize, 1); |
if (cp != CMFAIL) { |
mchunkptr newp = (mchunkptr)(cp + offset); |
size_t psize = newmmsize - offset - MMAP_FOOT_PAD; |
newp->head = (psize|CINUSE_BIT); |
mark_inuse_foot(m, newp, psize); |
chunk_plus_offset(newp, psize)->head = FENCEPOST_HEAD; |
chunk_plus_offset(newp, psize+SIZE_T_SIZE)->head = 0; |
|
if (cp < m->least_addr) |
m->least_addr = cp; |
if ((m->footprint += newmmsize - oldmmsize) > m->max_footprint) |
m->max_footprint = m->footprint; |
check_mmapped_chunk(m, newp); |
return newp; |
} |
} |
return 0; |
} |
|
/* -------------------------- mspace management -------------------------- */ |
|
/* Initialize top chunk and its size */ |
static void init_top(mstate m, mchunkptr p, size_t psize) { |
/* Ensure alignment */ |
size_t offset = align_offset(chunk2mem(p)); |
p = (mchunkptr)((char*)p + offset); |
psize -= offset; |
|
m->top = p; |
m->topsize = psize; |
p->head = psize | PINUSE_BIT; |
/* set size of fake trailing chunk holding overhead space only once */ |
chunk_plus_offset(p, psize)->head = TOP_FOOT_SIZE; |
m->trim_check = mparams.trim_threshold; /* reset on each update */ |
} |
|
/* Initialize bins for a new mstate that is otherwise zeroed out */ |
static void init_bins(mstate m) { |
/* Establish circular links for smallbins */ |
bindex_t i; |
for (i = 0; i < NSMALLBINS; ++i) { |
sbinptr bin = smallbin_at(m,i); |
bin->fd = bin->bk = bin; |
} |
} |
|
#if PROCEED_ON_ERROR |
|
/* default corruption action */ |
static void reset_on_error(mstate m) { |
int i; |
++malloc_corruption_error_count; |
/* Reinitialize fields to forget about all memory */ |
m->smallbins = m->treebins = 0; |
m->dvsize = m->topsize = 0; |
m->seg.base = 0; |
m->seg.size = 0; |
m->seg.next = 0; |
m->top = m->dv = 0; |
for (i = 0; i < NTREEBINS; ++i) |
*treebin_at(m, i) = 0; |
init_bins(m); |
} |
#endif /* PROCEED_ON_ERROR */ |
|
/* Allocate chunk and prepend remainder with chunk in successor base. */ |
static void* prepend_alloc(mstate m, char* newbase, char* oldbase, |
size_t nb) { |
mchunkptr p = align_as_chunk(newbase); |
mchunkptr oldfirst = align_as_chunk(oldbase); |
size_t psize = (char*)oldfirst - (char*)p; |
mchunkptr q = chunk_plus_offset(p, nb); |
size_t qsize = psize - nb; |
set_size_and_pinuse_of_inuse_chunk(m, p, nb); |
|
assert((char*)oldfirst > (char*)q); |
assert(pinuse(oldfirst)); |
assert(qsize >= MIN_CHUNK_SIZE); |
|
/* consolidate remainder with first chunk of old base */ |
if (oldfirst == m->top) { |
size_t tsize = m->topsize += qsize; |
m->top = q; |
q->head = tsize | PINUSE_BIT; |
check_top_chunk(m, q); |
} |
else if (oldfirst == m->dv) { |
size_t dsize = m->dvsize += qsize; |
m->dv = q; |
set_size_and_pinuse_of_free_chunk(q, dsize); |
} |
else { |
if (!cinuse(oldfirst)) { |
size_t nsize = chunksize(oldfirst); |
unlink_chunk(m, oldfirst, nsize); |
oldfirst = chunk_plus_offset(oldfirst, nsize); |
qsize += nsize; |
} |
set_free_with_pinuse(q, qsize, oldfirst); |
insert_chunk(m, q, qsize); |
check_free_chunk(m, q); |
} |
|
check_malloced_chunk(m, chunk2mem(p), nb); |
return chunk2mem(p); |
} |
|
|
/* Add a segment to hold a new noncontiguous region */ |
static void add_segment(mstate m, char* tbase, size_t tsize, flag_t mmapped) { |
/* Determine locations and sizes of segment, fenceposts, old top */ |
char* old_top = (char*)m->top; |
msegmentptr oldsp = segment_holding(m, old_top); |
char* old_end = oldsp->base + oldsp->size; |
size_t ssize = pad_request(sizeof(struct malloc_segment)); |
char* rawsp = old_end - (ssize + FOUR_SIZE_T_SIZES + CHUNK_ALIGN_MASK); |
size_t offset = align_offset(chunk2mem(rawsp)); |
char* asp = rawsp + offset; |
char* csp = (asp < (old_top + MIN_CHUNK_SIZE))? old_top : asp; |
mchunkptr sp = (mchunkptr)csp; |
msegmentptr ss = (msegmentptr)(chunk2mem(sp)); |
mchunkptr tnext = chunk_plus_offset(sp, ssize); |
mchunkptr p = tnext; |
int nfences = 0; |
|
/* reset top to new space */ |
init_top(m, (mchunkptr)tbase, tsize - TOP_FOOT_SIZE); |
|
/* Set up segment record */ |
assert(is_aligned(ss)); |
set_size_and_pinuse_of_inuse_chunk(m, sp, ssize); |
*ss = m->seg; /* Push current record */ |
m->seg.base = tbase; |
m->seg.size = tsize; |
m->seg.sflags = mmapped; |
m->seg.next = ss; |
|
/* Insert trailing fenceposts */ |
for (;;) { |
mchunkptr nextp = chunk_plus_offset(p, SIZE_T_SIZE); |
p->head = FENCEPOST_HEAD; |
++nfences; |
if ((char*)(&(nextp->head)) < old_end) |
p = nextp; |
else |
break; |
} |
assert(nfences >= 2); |
|
/* Insert the rest of old top into a bin as an ordinary free chunk */ |
if (csp != old_top) { |
mchunkptr q = (mchunkptr)old_top; |
size_t psize = csp - old_top; |
mchunkptr tn = chunk_plus_offset(q, psize); |
set_free_with_pinuse(q, psize, tn); |
insert_chunk(m, q, psize); |
} |
|
check_top_chunk(m, m->top); |
} |
|
/* -------------------------- System allocation -------------------------- */ |
|
/* Get memory from system using MORECORE or MMAP */ |
static void* sys_alloc(mstate m, size_t nb) { |
char* tbase = CMFAIL; |
size_t tsize = 0; |
flag_t mmap_flag = 0; |
|
init_mparams(); |
|
/* Directly map large chunks */ |
if (use_mmap(m) && nb >= mparams.mmap_threshold) { |
void* mem = mmap_alloc(m, nb); |
if (mem != 0) |
return mem; |
} |
|
/* |
Try getting memory in any of three ways (in most-preferred to |
least-preferred order): |
1. A call to MORECORE that can normally contiguously extend memory. |
(disabled if not MORECORE_CONTIGUOUS or not HAVE_MORECORE or |
or main space is mmapped or a previous contiguous call failed) |
2. A call to MMAP new space (disabled if not HAVE_MMAP). |
Note that under the default settings, if MORECORE is unable to |
fulfill a request, and HAVE_MMAP is true, then mmap is |
used as a noncontiguous system allocator. This is a useful backup |
strategy for systems with holes in address spaces -- in this case |
sbrk cannot contiguously expand the heap, but mmap may be able to |
find space. |
3. A call to MORECORE that cannot usually contiguously extend memory. |
(disabled if not HAVE_MORECORE) |
*/ |
|
if (MORECORE_CONTIGUOUS && !use_noncontiguous(m)) { |
char* br = CMFAIL; |
msegmentptr ss = (m->top == 0)? 0 : segment_holding(m, (char*)m->top); |
size_t asize = 0; |
ACQUIRE_MORECORE_LOCK(); |
|
if (ss == 0) { /* First time through or recovery */ |
char* base = (char*)CALL_MORECORE(0); |
if (base != CMFAIL) { |
asize = granularity_align(nb + TOP_FOOT_SIZE + SIZE_T_ONE); |
/* Adjust to end on a page boundary */ |
if (!is_page_aligned(base)) |
asize += (page_align((size_t)base) - (size_t)base); |
/* Can't call MORECORE if size is negative when treated as signed */ |
if (asize < HALF_MAX_SIZE_T && |
(br = (char*)(CALL_MORECORE(asize))) == base) { |
tbase = base; |
tsize = asize; |
} |
} |
} |
else { |
/* Subtract out existing available top space from MORECORE request. */ |
asize = granularity_align(nb - m->topsize + TOP_FOOT_SIZE + SIZE_T_ONE); |
/* Use mem here only if it did continuously extend old space */ |
if (asize < HALF_MAX_SIZE_T && |
(br = (char*)(CALL_MORECORE(asize))) == ss->base+ss->size) { |
tbase = br; |
tsize = asize; |
} |
} |
|
if (tbase == CMFAIL) { /* Cope with partial failure */ |
if (br != CMFAIL) { /* Try to use/extend the space we did get */ |
if (asize < HALF_MAX_SIZE_T && |
asize < nb + TOP_FOOT_SIZE + SIZE_T_ONE) { |
size_t esize = granularity_align(nb + TOP_FOOT_SIZE + SIZE_T_ONE - asize); |
if (esize < HALF_MAX_SIZE_T) { |
char* end = (char*)CALL_MORECORE(esize); |
if (end != CMFAIL) |
asize += esize; |
else { /* Can't use; try to release */ |
CALL_MORECORE(-asize); |
br = CMFAIL; |
} |
} |
} |
} |
if (br != CMFAIL) { /* Use the space we did get */ |
tbase = br; |
tsize = asize; |
} |
else |
disable_contiguous(m); /* Don't try contiguous path in the future */ |
} |
|
RELEASE_MORECORE_LOCK(); |
} |
|
if (HAVE_MMAP && tbase == CMFAIL) { /* Try MMAP */ |
size_t req = nb + TOP_FOOT_SIZE + SIZE_T_ONE; |
size_t rsize = granularity_align(req); |
if (rsize > nb) { /* Fail if wraps around zero */ |
char* mp = (char*)(CALL_MMAP(rsize)); |
if (mp != CMFAIL) { |
tbase = mp; |
tsize = rsize; |
mmap_flag = IS_MMAPPED_BIT; |
} |
} |
} |
|
if (HAVE_MORECORE && tbase == CMFAIL) { /* Try noncontiguous MORECORE */ |
size_t asize = granularity_align(nb + TOP_FOOT_SIZE + SIZE_T_ONE); |
if (asize < HALF_MAX_SIZE_T) { |
char* br = CMFAIL; |
char* end = CMFAIL; |
ACQUIRE_MORECORE_LOCK(); |
br = (char*)(CALL_MORECORE(asize)); |
end = (char*)(CALL_MORECORE(0)); |
RELEASE_MORECORE_LOCK(); |
if (br != CMFAIL && end != CMFAIL && br < end) { |
size_t ssize = end - br; |
if (ssize > nb + TOP_FOOT_SIZE) { |
tbase = br; |
tsize = ssize; |
} |
} |
} |
} |
|
if (tbase != CMFAIL) { |
|
if ((m->footprint += tsize) > m->max_footprint) |
m->max_footprint = m->footprint; |
|
if (!is_initialized(m)) { /* first-time initialization */ |
m->seg.base = m->least_addr = tbase; |
m->seg.size = tsize; |
m->seg.sflags = mmap_flag; |
m->magic = mparams.magic; |
init_bins(m); |
if (is_global(m)) |
init_top(m, (mchunkptr)tbase, tsize - TOP_FOOT_SIZE); |
else { |
/* Offset top by embedded malloc_state */ |
mchunkptr mn = next_chunk(mem2chunk(m)); |
init_top(m, mn, (size_t)((tbase + tsize) - (char*)mn) -TOP_FOOT_SIZE); |
} |
} |
|
else { |
/* Try to merge with an existing segment */ |
msegmentptr sp = &m->seg; |
while (sp != 0 && tbase != sp->base + sp->size) |
sp = sp->next; |
if (sp != 0 && |
!is_extern_segment(sp) && |
(sp->sflags & IS_MMAPPED_BIT) == mmap_flag && |
segment_holds(sp, m->top)) { /* append */ |
sp->size += tsize; |
init_top(m, m->top, m->topsize + tsize); |
} |
else { |
if (tbase < m->least_addr) |
m->least_addr = tbase; |
sp = &m->seg; |
while (sp != 0 && sp->base != tbase + tsize) |
sp = sp->next; |
if (sp != 0 && |
!is_extern_segment(sp) && |
(sp->sflags & IS_MMAPPED_BIT) == mmap_flag) { |
char* oldbase = sp->base; |
sp->base = tbase; |
sp->size += tsize; |
return prepend_alloc(m, tbase, oldbase, nb); |
} |
else |
add_segment(m, tbase, tsize, mmap_flag); |
} |
} |
|
if (nb < m->topsize) { /* Allocate from new or extended top space */ |
size_t rsize = m->topsize -= nb; |
mchunkptr p = m->top; |
mchunkptr r = m->top = chunk_plus_offset(p, nb); |
r->head = rsize | PINUSE_BIT; |
set_size_and_pinuse_of_inuse_chunk(m, p, nb); |
check_top_chunk(m, m->top); |
check_malloced_chunk(m, chunk2mem(p), nb); |
return chunk2mem(p); |
} |
} |
|
MALLOC_FAILURE_ACTION; |
return 0; |
} |
|
/* ----------------------- system deallocation -------------------------- */ |
|
/* Unmap and unlink any mmapped segments that don't contain used chunks */ |
static size_t release_unused_segments(mstate m) { |
size_t released = 0; |
msegmentptr pred = &m->seg; |
msegmentptr sp = pred->next; |
while (sp != 0) { |
char* base = sp->base; |
size_t size = sp->size; |
msegmentptr next = sp->next; |
if (is_mmapped_segment(sp) && !is_extern_segment(sp)) { |
mchunkptr p = align_as_chunk(base); |
size_t psize = chunksize(p); |
/* Can unmap if first chunk holds entire segment and not pinned */ |
if (!cinuse(p) && (char*)p + psize >= base + size - TOP_FOOT_SIZE) { |
tchunkptr tp = (tchunkptr)p; |
assert(segment_holds(sp, (char*)sp)); |
if (p == m->dv) { |
m->dv = 0; |
m->dvsize = 0; |
} |
else { |
unlink_large_chunk(m, tp); |
} |
if (CALL_MUNMAP(base, size) == 0) { |
released += size; |
m->footprint -= size; |
/* unlink obsoleted record */ |
sp = pred; |
sp->next = next; |
} |
else { /* back out if cannot unmap */ |
insert_large_chunk(m, tp, psize); |
} |
} |
} |
pred = sp; |
sp = next; |
} |
return released; |
} |
|
static int sys_trim(mstate m, size_t pad) { |
size_t released = 0; |
if (pad < MAX_REQUEST && is_initialized(m)) { |
pad += TOP_FOOT_SIZE; /* ensure enough room for segment overhead */ |
|
if (m->topsize > pad) { |
/* Shrink top space in granularity-size units, keeping at least one */ |
size_t unit = mparams.granularity; |
size_t extra = ((m->topsize - pad + (unit - SIZE_T_ONE)) / unit - |
SIZE_T_ONE) * unit; |
msegmentptr sp = segment_holding(m, (char*)m->top); |
|
if (!is_extern_segment(sp)) { |
if (is_mmapped_segment(sp)) { |
if (HAVE_MMAP && |
sp->size >= extra && |
!has_segment_link(m, sp)) { /* can't shrink if pinned */ |
size_t newsize = sp->size - extra; |
/* Prefer mremap, fall back to munmap */ |
if ((CALL_MREMAP(sp->base, sp->size, newsize, 0) != MFAIL) || |
(CALL_MUNMAP(sp->base + newsize, extra) == 0)) { |
released = extra; |
} |
} |
} |
else if (HAVE_MORECORE) { |
if (extra >= HALF_MAX_SIZE_T) /* Avoid wrapping negative */ |
extra = (HALF_MAX_SIZE_T) + SIZE_T_ONE - unit; |
ACQUIRE_MORECORE_LOCK(); |
{ |
/* Make sure end of memory is where we last set it. */ |
char* old_br = (char*)(CALL_MORECORE(0)); |
if (old_br == sp->base + sp->size) { |
char* rel_br = (char*)(CALL_MORECORE(-extra)); |
char* new_br = (char*)(CALL_MORECORE(0)); |
if (rel_br != CMFAIL && new_br < old_br) |
released = old_br - new_br; |
} |
} |
RELEASE_MORECORE_LOCK(); |
} |
} |
|
if (released != 0) { |
sp->size -= released; |
m->footprint -= released; |
init_top(m, m->top, m->topsize - released); |
check_top_chunk(m, m->top); |
} |
} |
|
/* Unmap any unused mmapped segments */ |
if (HAVE_MMAP) |
released += release_unused_segments(m); |
|
/* On failure, disable autotrim to avoid repeated failed future calls */ |
if (released == 0) |
m->trim_check = MAX_SIZE_T; |
} |
|
return (released != 0)? 1 : 0; |
} |
|
/* ---------------------------- malloc support --------------------------- */ |
|
/* allocate a large request from the best fitting chunk in a treebin */ |
static void* tmalloc_large(mstate m, size_t nb) { |
tchunkptr v = 0; |
size_t rsize = -nb; /* Unsigned negation */ |
tchunkptr t; |
bindex_t idx; |
compute_tree_index(nb, idx); |
|
if ((t = *treebin_at(m, idx)) != 0) { |
/* Traverse tree for this bin looking for node with size == nb */ |
size_t sizebits = nb << leftshift_for_tree_index(idx); |
tchunkptr rst = 0; /* The deepest untaken right subtree */ |
for (;;) { |
tchunkptr rt; |
size_t trem = chunksize(t) - nb; |
if (trem < rsize) { |
v = t; |
if ((rsize = trem) == 0) |
break; |
} |
rt = t->child[1]; |
t = t->child[(sizebits >> (SIZE_T_BITSIZE-SIZE_T_ONE)) & 1]; |
if (rt != 0 && rt != t) |
rst = rt; |
if (t == 0) { |
t = rst; /* set t to least subtree holding sizes > nb */ |
break; |
} |
sizebits <<= 1; |
} |
} |
|
if (t == 0 && v == 0) { /* set t to root of next non-empty treebin */ |
binmap_t leftbits = left_bits(idx2bit(idx)) & m->treemap; |
if (leftbits != 0) { |
bindex_t i; |
binmap_t leastbit = least_bit(leftbits); |
compute_bit2idx(leastbit, i); |
t = *treebin_at(m, i); |
} |
} |
|
while (t != 0) { /* find smallest of tree or subtree */ |
size_t trem = chunksize(t) - nb; |
if (trem < rsize) { |
rsize = trem; |
v = t; |
} |
t = leftmost_child(t); |
} |
|
/* If dv is a better fit, return 0 so malloc will use it */ |
if (v != 0 && rsize < (size_t)(m->dvsize - nb)) { |
if (RTCHECK(ok_address(m, v))) { /* split */ |
mchunkptr r = chunk_plus_offset(v, nb); |
assert(chunksize(v) == rsize + nb); |
if (RTCHECK(ok_next(v, r))) { |
unlink_large_chunk(m, v); |
if (rsize < MIN_CHUNK_SIZE) |
set_inuse_and_pinuse(m, v, (rsize + nb)); |
else { |
set_size_and_pinuse_of_inuse_chunk(m, v, nb); |
set_size_and_pinuse_of_free_chunk(r, rsize); |
insert_chunk(m, r, rsize); |
} |
return chunk2mem(v); |
} |
} |
CORRUPTION_ERROR_ACTION(m); |
} |
return 0; |
} |
|
/* allocate a small request from the best fitting chunk in a treebin */ |
static void* tmalloc_small(mstate m, size_t nb) { |
tchunkptr t, v; |
size_t rsize; |
bindex_t i; |
binmap_t leastbit = least_bit(m->treemap); |
compute_bit2idx(leastbit, i); |
|
v = t = *treebin_at(m, i); |
rsize = chunksize(t) - nb; |
|
while ((t = leftmost_child(t)) != 0) { |
size_t trem = chunksize(t) - nb; |
if (trem < rsize) { |
rsize = trem; |
v = t; |
} |
} |
|
if (RTCHECK(ok_address(m, v))) { |
mchunkptr r = chunk_plus_offset(v, nb); |
assert(chunksize(v) == rsize + nb); |
if (RTCHECK(ok_next(v, r))) { |
unlink_large_chunk(m, v); |
if (rsize < MIN_CHUNK_SIZE) |
set_inuse_and_pinuse(m, v, (rsize + nb)); |
else { |
set_size_and_pinuse_of_inuse_chunk(m, v, nb); |
set_size_and_pinuse_of_free_chunk(r, rsize); |
replace_dv(m, r, rsize); |
} |
return chunk2mem(v); |
} |
} |
|
CORRUPTION_ERROR_ACTION(m); |
return 0; |
} |
|
/* --------------------------- realloc support --------------------------- */ |
|
static void* internal_realloc(mstate m, void* oldmem, size_t bytes) { |
if (bytes >= MAX_REQUEST) { |
MALLOC_FAILURE_ACTION; |
return 0; |
} |
if (!PREACTION(m)) { |
mchunkptr oldp = mem2chunk(oldmem); |
size_t oldsize = chunksize(oldp); |
mchunkptr next = chunk_plus_offset(oldp, oldsize); |
mchunkptr newp = 0; |
void* extra = 0; |
|
/* Try to either shrink or extend into top. Else malloc-copy-free */ |
|
if (RTCHECK(ok_address(m, oldp) && ok_cinuse(oldp) && |
ok_next(oldp, next) && ok_pinuse(next))) { |
size_t nb = request2size(bytes); |
if (is_mmapped(oldp)) |
newp = mmap_resize(m, oldp, nb); |
else if (oldsize >= nb) { /* already big enough */ |
size_t rsize = oldsize - nb; |
newp = oldp; |
if (rsize >= MIN_CHUNK_SIZE) { |
mchunkptr remainder = chunk_plus_offset(newp, nb); |
set_inuse(m, newp, nb); |
set_inuse(m, remainder, rsize); |
extra = chunk2mem(remainder); |
} |
} |
else if (next == m->top && oldsize + m->topsize > nb) { |
/* Expand into top */ |
size_t newsize = oldsize + m->topsize; |
size_t newtopsize = newsize - nb; |
mchunkptr newtop = chunk_plus_offset(oldp, nb); |
set_inuse(m, oldp, nb); |
newtop->head = newtopsize |PINUSE_BIT; |
m->top = newtop; |
m->topsize = newtopsize; |
newp = oldp; |
} |
} |
else { |
USAGE_ERROR_ACTION(m, oldmem); |
POSTACTION(m); |
return 0; |
} |
|
POSTACTION(m); |
|
if (newp != 0) { |
if (extra != 0) { |
internal_free(m, extra); |
} |
check_inuse_chunk(m, newp); |
return chunk2mem(newp); |
} |
else { |
void* newmem = internal_malloc(m, bytes); |
if (newmem != 0) { |
size_t oc = oldsize - overhead_for(oldp); |
memcpy(newmem, oldmem, (oc < bytes)? oc : bytes); |
internal_free(m, oldmem); |
} |
return newmem; |
} |
} |
return 0; |
} |
|
/* --------------------------- memalign support -------------------------- */ |
|
static void* internal_memalign(mstate m, size_t alignment, size_t bytes) { |
if (alignment <= MALLOC_ALIGNMENT) /* Can just use malloc */ |
return internal_malloc(m, bytes); |
if (alignment < MIN_CHUNK_SIZE) /* must be at least a minimum chunk size */ |
alignment = MIN_CHUNK_SIZE; |
if ((alignment & (alignment-SIZE_T_ONE)) != 0) {/* Ensure a power of 2 */ |
size_t a = MALLOC_ALIGNMENT << 1; |
while (a < alignment) a <<= 1; |
alignment = a; |
} |
|
if (bytes >= MAX_REQUEST - alignment) { |
if (m != 0) { /* Test isn't needed but avoids compiler warning */ |
MALLOC_FAILURE_ACTION; |
} |
} |
else { |
size_t nb = request2size(bytes); |
size_t req = nb + alignment + MIN_CHUNK_SIZE - CHUNK_OVERHEAD; |
char* mem = (char*)internal_malloc(m, req); |
if (mem != 0) { |
void* leader = 0; |
void* trailer = 0; |
mchunkptr p = mem2chunk(mem); |
|
if (PREACTION(m)) return 0; |
if ((((size_t)(mem)) % alignment) != 0) { /* misaligned */ |
/* |
Find an aligned spot inside chunk. Since we need to give |
back leading space in a chunk of at least MIN_CHUNK_SIZE, if |
the first calculation places us at a spot with less than |
MIN_CHUNK_SIZE leader, we can move to the next aligned spot. |
We've allocated enough total room so that this is always |
possible. |
*/ |
char* br = (char*)mem2chunk((size_t)(((size_t)(mem + |
alignment - |
SIZE_T_ONE)) & |
-alignment)); |
char* pos = ((size_t)(br - (char*)(p)) >= MIN_CHUNK_SIZE)? |
br : br+alignment; |
mchunkptr newp = (mchunkptr)pos; |
size_t leadsize = pos - (char*)(p); |
size_t newsize = chunksize(p) - leadsize; |
|
if (is_mmapped(p)) { /* For mmapped chunks, just adjust offset */ |
newp->prev_foot = p->prev_foot + leadsize; |
newp->head = (newsize|CINUSE_BIT); |
} |
else { /* Otherwise, give back leader, use the rest */ |
set_inuse(m, newp, newsize); |
set_inuse(m, p, leadsize); |
leader = chunk2mem(p); |
} |
p = newp; |
} |
|
/* Give back spare room at the end */ |
if (!is_mmapped(p)) { |
size_t size = chunksize(p); |
if (size > nb + MIN_CHUNK_SIZE) { |
size_t remainder_size = size - nb; |
mchunkptr remainder = chunk_plus_offset(p, nb); |
set_inuse(m, p, nb); |
set_inuse(m, remainder, remainder_size); |
trailer = chunk2mem(remainder); |
} |
} |
|
assert (chunksize(p) >= nb); |
assert((((size_t)(chunk2mem(p))) % alignment) == 0); |
check_inuse_chunk(m, p); |
POSTACTION(m); |
if (leader != 0) { |
internal_free(m, leader); |
} |
if (trailer != 0) { |
internal_free(m, trailer); |
} |
return chunk2mem(p); |
} |
} |
return 0; |
} |
|
/* ------------------------ comalloc/coalloc support --------------------- */ |
|
static void** ialloc(mstate m, |
size_t n_elements, |
size_t* sizes, |
int opts, |
void* chunks[]) { |
/* |
This provides common support for independent_X routines, handling |
all of the combinations that can result. |
|
The opts arg has: |
bit 0 set if all elements are same size (using sizes[0]) |
bit 1 set if elements should be zeroed |
*/ |
|
size_t element_size; /* chunksize of each element, if all same */ |
size_t contents_size; /* total size of elements */ |
size_t array_size; /* request size of pointer array */ |
void* mem; /* malloced aggregate space */ |
mchunkptr p; /* corresponding chunk */ |
size_t remainder_size; /* remaining bytes while splitting */ |
void** marray; /* either "chunks" or malloced ptr array */ |
mchunkptr array_chunk; /* chunk for malloced ptr array */ |
flag_t was_enabled; /* to disable mmap */ |
size_t size; |
size_t i; |
|
/* compute array length, if needed */ |
if (chunks != 0) { |
if (n_elements == 0) |
return chunks; /* nothing to do */ |
marray = chunks; |
array_size = 0; |
} |
else { |
/* if empty req, must still return chunk representing empty array */ |
if (n_elements == 0) |
return (void**)internal_malloc(m, 0); |
marray = 0; |
array_size = request2size(n_elements * (sizeof(void*))); |
} |
|
/* compute total element size */ |
if (opts & 0x1) { /* all-same-size */ |
element_size = request2size(*sizes); |
contents_size = n_elements * element_size; |
} |
else { /* add up all the sizes */ |
element_size = 0; |
contents_size = 0; |
for (i = 0; i != n_elements; ++i) |
contents_size += request2size(sizes[i]); |
} |
|
size = contents_size + array_size; |
|
/* |
Allocate the aggregate chunk. First disable direct-mmapping so |
malloc won't use it, since we would not be able to later |
free/realloc space internal to a segregated mmap region. |
*/ |
was_enabled = use_mmap(m); |
disable_mmap(m); |
mem = internal_malloc(m, size - CHUNK_OVERHEAD); |
if (was_enabled) |
enable_mmap(m); |
if (mem == 0) |
return 0; |
|
if (PREACTION(m)) return 0; |
p = mem2chunk(mem); |
remainder_size = chunksize(p); |
|
assert(!is_mmapped(p)); |
|
if (opts & 0x2) { /* optionally clear the elements */ |
memset((size_t*)mem, 0, remainder_size - SIZE_T_SIZE - array_size); |
} |
|
/* If not provided, allocate the pointer array as final part of chunk */ |
if (marray == 0) { |
size_t array_chunk_size; |
array_chunk = chunk_plus_offset(p, contents_size); |
array_chunk_size = remainder_size - contents_size; |
marray = (void**) (chunk2mem(array_chunk)); |
set_size_and_pinuse_of_inuse_chunk(m, array_chunk, array_chunk_size); |
remainder_size = contents_size; |
} |
|
/* split out elements */ |
for (i = 0; ; ++i) { |
marray[i] = chunk2mem(p); |
if (i != n_elements-1) { |
if (element_size != 0) |
size = element_size; |
else |
size = request2size(sizes[i]); |
remainder_size -= size; |
set_size_and_pinuse_of_inuse_chunk(m, p, size); |
p = chunk_plus_offset(p, size); |
} |
else { /* the final element absorbs any overallocation slop */ |
set_size_and_pinuse_of_inuse_chunk(m, p, remainder_size); |
break; |
} |
} |
|
#if DEBUG |
if (marray != chunks) { |
/* final element must have exactly exhausted chunk */ |
if (element_size != 0) { |
assert(remainder_size == element_size); |
} |
else { |
assert(remainder_size == request2size(sizes[i])); |
} |
check_inuse_chunk(m, mem2chunk(marray)); |
} |
for (i = 0; i != n_elements; ++i) |
check_inuse_chunk(m, mem2chunk(marray[i])); |
|
#endif /* DEBUG */ |
|
POSTACTION(m); |
return marray; |
} |
|
|
/* -------------------------- public routines ---------------------------- */ |
|
#if !ONLY_MSPACES |
|
void* dlmalloc(size_t bytes) { |
/* |
Basic algorithm: |
If a small request (< 256 bytes minus per-chunk overhead): |
1. If one exists, use a remainderless chunk in associated smallbin. |
(Remainderless means that there are too few excess bytes to |
represent as a chunk.) |
2. If it is big enough, use the dv chunk, which is normally the |
chunk adjacent to the one used for the most recent small request. |
3. If one exists, split the smallest available chunk in a bin, |
saving remainder in dv. |
4. If it is big enough, use the top chunk. |
5. If available, get memory from system and use it |
Otherwise, for a large request: |
1. Find the smallest available binned chunk that fits, and use it |
if it is better fitting than dv chunk, splitting if necessary. |
2. If better fitting than any binned chunk, use the dv chunk. |
3. If it is big enough, use the top chunk. |
4. If request size >= mmap threshold, try to directly mmap this chunk. |
5. If available, get memory from system and use it |
|
The ugly goto's here ensure that postaction occurs along all paths. |
*/ |
|
if (!PREACTION(gm)) { |
void* mem; |
size_t nb; |
if (bytes <= MAX_SMALL_REQUEST) { |
bindex_t idx; |
binmap_t smallbits; |
nb = (bytes < MIN_REQUEST)? MIN_CHUNK_SIZE : pad_request(bytes); |
idx = small_index(nb); |
smallbits = gm->smallmap >> idx; |
|
if ((smallbits & 0x3U) != 0) { /* Remainderless fit to a smallbin. */ |
mchunkptr b, p; |
idx += ~smallbits & 1; /* Uses next bin if idx empty */ |
b = smallbin_at(gm, idx); |
p = b->fd; |
assert(chunksize(p) == small_index2size(idx)); |
unlink_first_small_chunk(gm, b, p, idx); |
set_inuse_and_pinuse(gm, p, small_index2size(idx)); |
mem = chunk2mem(p); |
check_malloced_chunk(gm, mem, nb); |
goto postaction; |
} |
|
else if (nb > gm->dvsize) { |
if (smallbits != 0) { /* Use chunk in next nonempty smallbin */ |
mchunkptr b, p, r; |
size_t rsize; |
bindex_t i; |
binmap_t leftbits = (smallbits << idx) & left_bits(idx2bit(idx)); |
binmap_t leastbit = least_bit(leftbits); |
compute_bit2idx(leastbit, i); |
b = smallbin_at(gm, i); |
p = b->fd; |
assert(chunksize(p) == small_index2size(i)); |
unlink_first_small_chunk(gm, b, p, i); |
rsize = small_index2size(i) - nb; |
/* Fit here cannot be remainderless if 4byte sizes */ |
if (SIZE_T_SIZE != 4 && rsize < MIN_CHUNK_SIZE) |
set_inuse_and_pinuse(gm, p, small_index2size(i)); |
else { |
set_size_and_pinuse_of_inuse_chunk(gm, p, nb); |
r = chunk_plus_offset(p, nb); |
set_size_and_pinuse_of_free_chunk(r, rsize); |
replace_dv(gm, r, rsize); |
} |
mem = chunk2mem(p); |
check_malloced_chunk(gm, mem, nb); |
goto postaction; |
} |
|
else if (gm->treemap != 0 && (mem = tmalloc_small(gm, nb)) != 0) { |
check_malloced_chunk(gm, mem, nb); |
goto postaction; |
} |
} |
} |
else if (bytes >= MAX_REQUEST) |
nb = MAX_SIZE_T; /* Too big to allocate. Force failure (in sys alloc) */ |
else { |
nb = pad_request(bytes); |
if (gm->treemap != 0 && (mem = tmalloc_large(gm, nb)) != 0) { |
check_malloced_chunk(gm, mem, nb); |
goto postaction; |
} |
} |
|
if (nb <= gm->dvsize) { |
size_t rsize = gm->dvsize - nb; |
mchunkptr p = gm->dv; |
if (rsize >= MIN_CHUNK_SIZE) { /* split dv */ |
mchunkptr r = gm->dv = chunk_plus_offset(p, nb); |
gm->dvsize = rsize; |
set_size_and_pinuse_of_free_chunk(r, rsize); |
set_size_and_pinuse_of_inuse_chunk(gm, p, nb); |
} |
else { /* exhaust dv */ |
size_t dvs = gm->dvsize; |
gm->dvsize = 0; |
gm->dv = 0; |
set_inuse_and_pinuse(gm, p, dvs); |
} |
mem = chunk2mem(p); |
check_malloced_chunk(gm, mem, nb); |
goto postaction; |
} |
|
else if (nb < gm->topsize) { /* Split top */ |
size_t rsize = gm->topsize -= nb; |
mchunkptr p = gm->top; |
mchunkptr r = gm->top = chunk_plus_offset(p, nb); |
r->head = rsize | PINUSE_BIT; |
set_size_and_pinuse_of_inuse_chunk(gm, p, nb); |
mem = chunk2mem(p); |
check_top_chunk(gm, gm->top); |
check_malloced_chunk(gm, mem, nb); |
goto postaction; |
} |
|
mem = sys_alloc(gm, nb); |
|
postaction: |
POSTACTION(gm); |
return mem; |
} |
|
return 0; |
} |
|
void dlfree(void* mem) { |
/* |
Consolidate freed chunks with preceeding or succeeding bordering |
free chunks, if they exist, and then place in a bin. Intermixed |
with special cases for top, dv, mmapped chunks, and usage errors. |
*/ |
|
if (mem != 0) { |
mchunkptr p = mem2chunk(mem); |
#if FOOTERS |
mstate fm = get_mstate_for(p); |
if (!ok_magic(fm)) { |
USAGE_ERROR_ACTION(fm, p); |
return; |
} |
#else /* FOOTERS */ |
#define fm gm |
#endif /* FOOTERS */ |
if (!PREACTION(fm)) { |
check_inuse_chunk(fm, p); |
if (RTCHECK(ok_address(fm, p) && ok_cinuse(p))) { |
size_t psize = chunksize(p); |
mchunkptr next = chunk_plus_offset(p, psize); |
if (!pinuse(p)) { |
size_t prevsize = p->prev_foot; |
if ((prevsize & IS_MMAPPED_BIT) != 0) { |
prevsize &= ~IS_MMAPPED_BIT; |
psize += prevsize + MMAP_FOOT_PAD; |
if (CALL_MUNMAP((char*)p - prevsize, psize) == 0) |
fm->footprint -= psize; |
goto postaction; |
} |
else { |
mchunkptr prev = chunk_minus_offset(p, prevsize); |
psize += prevsize; |
p = prev; |
if (RTCHECK(ok_address(fm, prev))) { /* consolidate backward */ |
if (p != fm->dv) { |
unlink_chunk(fm, p, prevsize); |
} |
else if ((next->head & INUSE_BITS) == INUSE_BITS) { |
fm->dvsize = psize; |
set_free_with_pinuse(p, psize, next); |
goto postaction; |
} |
} |
else |
goto erroraction; |
} |
} |
|
if (RTCHECK(ok_next(p, next) && ok_pinuse(next))) { |
if (!cinuse(next)) { /* consolidate forward */ |
if (next == fm->top) { |
size_t tsize = fm->topsize += psize; |
fm->top = p; |
p->head = tsize | PINUSE_BIT; |
if (p == fm->dv) { |
fm->dv = 0; |
fm->dvsize = 0; |
} |
if (should_trim(fm, tsize)) |
sys_trim(fm, 0); |
goto postaction; |
} |
else if (next == fm->dv) { |
size_t dsize = fm->dvsize += psize; |
fm->dv = p; |
set_size_and_pinuse_of_free_chunk(p, dsize); |
goto postaction; |
} |
else { |
size_t nsize = chunksize(next); |
psize += nsize; |
unlink_chunk(fm, next, nsize); |
set_size_and_pinuse_of_free_chunk(p, psize); |
if (p == fm->dv) { |
fm->dvsize = psize; |
goto postaction; |
} |
} |
} |
else |
set_free_with_pinuse(p, psize, next); |
insert_chunk(fm, p, psize); |
check_free_chunk(fm, p); |
goto postaction; |
} |
} |
erroraction: |
USAGE_ERROR_ACTION(fm, p); |
postaction: |
POSTACTION(fm); |
} |
} |
#if !FOOTERS |
#undef fm |
#endif /* FOOTERS */ |
} |
|
void* dlcalloc(size_t n_elements, size_t elem_size) { |
void* mem; |
size_t req = 0; |
if (n_elements != 0) { |
req = n_elements * elem_size; |
if (((n_elements | elem_size) & ~(size_t)0xffff) && |
(req / n_elements != elem_size)) |
req = MAX_SIZE_T; /* force downstream failure on overflow */ |
} |
mem = dlmalloc(req); |
if (mem != 0 && calloc_must_clear(mem2chunk(mem))) |
memset(mem, 0, req); |
return mem; |
} |
|
void* dlrealloc(void* oldmem, size_t bytes) { |
if (oldmem == 0) |
return dlmalloc(bytes); |
#ifdef REALLOC_ZERO_BYTES_FREES |
if (bytes == 0) { |
dlfree(oldmem); |
return 0; |
} |
#endif /* REALLOC_ZERO_BYTES_FREES */ |
else { |
#if ! FOOTERS |
mstate m = gm; |
#else /* FOOTERS */ |
mstate m = get_mstate_for(mem2chunk(oldmem)); |
if (!ok_magic(m)) { |
USAGE_ERROR_ACTION(m, oldmem); |
return 0; |
} |
#endif /* FOOTERS */ |
return internal_realloc(m, oldmem, bytes); |
} |
} |
|
void* dlmemalign(size_t alignment, size_t bytes) { |
return internal_memalign(gm, alignment, bytes); |
} |
|
void** dlindependent_calloc(size_t n_elements, size_t elem_size, |
void* chunks[]) { |
size_t sz = elem_size; /* serves as 1-element array */ |
return ialloc(gm, n_elements, &sz, 3, chunks); |
} |
|
void** dlindependent_comalloc(size_t n_elements, size_t sizes[], |
void* chunks[]) { |
return ialloc(gm, n_elements, sizes, 0, chunks); |
} |
|
void* dlvalloc(size_t bytes) { |
size_t pagesz; |
init_mparams(); |
pagesz = mparams.page_size; |
return dlmemalign(pagesz, bytes); |
} |
|
void* dlpvalloc(size_t bytes) { |
size_t pagesz; |
init_mparams(); |
pagesz = mparams.page_size; |
return dlmemalign(pagesz, (bytes + pagesz - SIZE_T_ONE) & ~(pagesz - SIZE_T_ONE)); |
} |
|
int dlmalloc_trim(size_t pad) { |
int result = 0; |
if (!PREACTION(gm)) { |
result = sys_trim(gm, pad); |
POSTACTION(gm); |
} |
return result; |
} |
|
size_t dlmalloc_footprint(void) { |
return gm->footprint; |
} |
|
size_t dlmalloc_max_footprint(void) { |
return gm->max_footprint; |
} |
|
#if !NO_MALLINFO |
struct mallinfo dlmallinfo(void) { |
return internal_mallinfo(gm); |
} |
#endif /* NO_MALLINFO */ |
|
void dlmalloc_stats() { |
internal_malloc_stats(gm); |
} |
|
size_t dlmalloc_usable_size(void* mem) { |
if (mem != 0) { |
mchunkptr p = mem2chunk(mem); |
if (cinuse(p)) |
return chunksize(p) - overhead_for(p); |
} |
return 0; |
} |
|
int dlmallopt(int param_number, int value) { |
return change_mparam(param_number, value); |
} |
|
#endif /* !ONLY_MSPACES */ |
|
/* ----------------------------- user mspaces ---------------------------- */ |
|
#if MSPACES |
|
static mstate init_user_mstate(char* tbase, size_t tsize) { |
size_t msize = pad_request(sizeof(struct malloc_state)); |
mchunkptr mn; |
mchunkptr msp = align_as_chunk(tbase); |
mstate m = (mstate)(chunk2mem(msp)); |
memset(m, 0, msize); |
INITIAL_LOCK(&m->mutex); |
msp->head = (msize|PINUSE_BIT|CINUSE_BIT); |
m->seg.base = m->least_addr = tbase; |
m->seg.size = m->footprint = m->max_footprint = tsize; |
m->magic = mparams.magic; |
m->mflags = mparams.default_mflags; |
disable_contiguous(m); |
init_bins(m); |
mn = next_chunk(mem2chunk(m)); |
init_top(m, mn, (size_t)((tbase + tsize) - (char*)mn) - TOP_FOOT_SIZE); |
check_top_chunk(m, m->top); |
return m; |
} |
|
mspace create_mspace(size_t capacity, int locked) { |
mstate m = 0; |
size_t msize = pad_request(sizeof(struct malloc_state)); |
init_mparams(); /* Ensure pagesize etc initialized */ |
|
if (capacity < (size_t) -(msize + TOP_FOOT_SIZE + mparams.page_size)) { |
size_t rs = ((capacity == 0)? mparams.granularity : |
(capacity + TOP_FOOT_SIZE + msize)); |
size_t tsize = granularity_align(rs); |
char* tbase = (char*)(CALL_MMAP(tsize)); |
if (tbase != CMFAIL) { |
m = init_user_mstate(tbase, tsize); |
m->seg.sflags = IS_MMAPPED_BIT; |
set_lock(m, locked); |
} |
} |
return (mspace)m; |
} |
|
mspace create_mspace_with_base(void* base, size_t capacity, int locked) { |
mstate m = 0; |
size_t msize = pad_request(sizeof(struct malloc_state)); |
init_mparams(); /* Ensure pagesize etc initialized */ |
|
if (capacity > msize + TOP_FOOT_SIZE && |
capacity < (size_t) -(msize + TOP_FOOT_SIZE + mparams.page_size)) { |
m = init_user_mstate((char*)base, capacity); |
m->seg.sflags = EXTERN_BIT; |
set_lock(m, locked); |
} |
return (mspace)m; |
} |
|
size_t destroy_mspace(mspace msp) { |
size_t freed = 0; |
mstate ms = (mstate)msp; |
if (ok_magic(ms)) { |
msegmentptr sp = &ms->seg; |
while (sp != 0) { |
char* base = sp->base; |
size_t size = sp->size; |
flag_t flag = sp->sflags; |
sp = sp->next; |
if ((flag & IS_MMAPPED_BIT) && !(flag & EXTERN_BIT) && |
CALL_MUNMAP(base, size) == 0) |
freed += size; |
} |
} |
else { |
USAGE_ERROR_ACTION(ms,ms); |
} |
return freed; |
} |
|
/* |
mspace versions of routines are near-clones of the global |
versions. This is not so nice but better than the alternatives. |
*/ |
|
|
void* mspace_malloc(mspace msp, size_t bytes) { |
mstate ms = (mstate)msp; |
if (!ok_magic(ms)) { |
USAGE_ERROR_ACTION(ms,ms); |
return 0; |
} |
if (!PREACTION(ms)) { |
void* mem; |
size_t nb; |
if (bytes <= MAX_SMALL_REQUEST) { |
bindex_t idx; |
binmap_t smallbits; |
nb = (bytes < MIN_REQUEST)? MIN_CHUNK_SIZE : pad_request(bytes); |
idx = small_index(nb); |
smallbits = ms->smallmap >> idx; |
|
if ((smallbits & 0x3U) != 0) { /* Remainderless fit to a smallbin. */ |
mchunkptr b, p; |
idx += ~smallbits & 1; /* Uses next bin if idx empty */ |
b = smallbin_at(ms, idx); |
p = b->fd; |
assert(chunksize(p) == small_index2size(idx)); |
unlink_first_small_chunk(ms, b, p, idx); |
set_inuse_and_pinuse(ms, p, small_index2size(idx)); |
mem = chunk2mem(p); |
check_malloced_chunk(ms, mem, nb); |
goto postaction; |
} |
|
else if (nb > ms->dvsize) { |
if (smallbits != 0) { /* Use chunk in next nonempty smallbin */ |
mchunkptr b, p, r; |
size_t rsize; |
bindex_t i; |
binmap_t leftbits = (smallbits << idx) & left_bits(idx2bit(idx)); |
binmap_t leastbit = least_bit(leftbits); |
compute_bit2idx(leastbit, i); |
b = smallbin_at(ms, i); |
p = b->fd; |
assert(chunksize(p) == small_index2size(i)); |
unlink_first_small_chunk(ms, b, p, i); |
rsize = small_index2size(i) - nb; |
/* Fit here cannot be remainderless if 4byte sizes */ |
if (SIZE_T_SIZE != 4 && rsize < MIN_CHUNK_SIZE) |
set_inuse_and_pinuse(ms, p, small_index2size(i)); |
else { |
set_size_and_pinuse_of_inuse_chunk(ms, p, nb); |
r = chunk_plus_offset(p, nb); |
set_size_and_pinuse_of_free_chunk(r, rsize); |
replace_dv(ms, r, rsize); |
} |
mem = chunk2mem(p); |
check_malloced_chunk(ms, mem, nb); |
goto postaction; |
} |
|
else if (ms->treemap != 0 && (mem = tmalloc_small(ms, nb)) != 0) { |
check_malloced_chunk(ms, mem, nb); |
goto postaction; |
} |
} |
} |
else if (bytes >= MAX_REQUEST) |
nb = MAX_SIZE_T; /* Too big to allocate. Force failure (in sys alloc) */ |
else { |
nb = pad_request(bytes); |
if (ms->treemap != 0 && (mem = tmalloc_large(ms, nb)) != 0) { |
check_malloced_chunk(ms, mem, nb); |
goto postaction; |
} |
} |
|
if (nb <= ms->dvsize) { |
size_t rsize = ms->dvsize - nb; |
mchunkptr p = ms->dv; |
if (rsize >= MIN_CHUNK_SIZE) { /* split dv */ |
mchunkptr r = ms->dv = chunk_plus_offset(p, nb); |
ms->dvsize = rsize; |
set_size_and_pinuse_of_free_chunk(r, rsize); |
set_size_and_pinuse_of_inuse_chunk(ms, p, nb); |
} |
else { /* exhaust dv */ |
size_t dvs = ms->dvsize; |
ms->dvsize = 0; |
ms->dv = 0; |
set_inuse_and_pinuse(ms, p, dvs); |
} |
mem = chunk2mem(p); |
check_malloced_chunk(ms, mem, nb); |
goto postaction; |
} |
|
else if (nb < ms->topsize) { /* Split top */ |
size_t rsize = ms->topsize -= nb; |
mchunkptr p = ms->top; |
mchunkptr r = ms->top = chunk_plus_offset(p, nb); |
r->head = rsize | PINUSE_BIT; |
set_size_and_pinuse_of_inuse_chunk(ms, p, nb); |
mem = chunk2mem(p); |
check_top_chunk(ms, ms->top); |
check_malloced_chunk(ms, mem, nb); |
goto postaction; |
} |
|
mem = sys_alloc(ms, nb); |
|
postaction: |
POSTACTION(ms); |
return mem; |
} |
|
return 0; |
} |
|
void mspace_free(mspace msp, void* mem) { |
if (mem != 0) { |
mchunkptr p = mem2chunk(mem); |
#if FOOTERS |
mstate fm = get_mstate_for(p); |
#else /* FOOTERS */ |
mstate fm = (mstate)msp; |
#endif /* FOOTERS */ |
if (!ok_magic(fm)) { |
USAGE_ERROR_ACTION(fm, p); |
return; |
} |
if (!PREACTION(fm)) { |
check_inuse_chunk(fm, p); |
if (RTCHECK(ok_address(fm, p) && ok_cinuse(p))) { |
size_t psize = chunksize(p); |
mchunkptr next = chunk_plus_offset(p, psize); |
if (!pinuse(p)) { |
size_t prevsize = p->prev_foot; |
if ((prevsize & IS_MMAPPED_BIT) != 0) { |
prevsize &= ~IS_MMAPPED_BIT; |
psize += prevsize + MMAP_FOOT_PAD; |
if (CALL_MUNMAP((char*)p - prevsize, psize) == 0) |
fm->footprint -= psize; |
goto postaction; |
} |
else { |
mchunkptr prev = chunk_minus_offset(p, prevsize); |
psize += prevsize; |
p = prev; |
if (RTCHECK(ok_address(fm, prev))) { /* consolidate backward */ |
if (p != fm->dv) { |
unlink_chunk(fm, p, prevsize); |
} |
else if ((next->head & INUSE_BITS) == INUSE_BITS) { |
fm->dvsize = psize; |
set_free_with_pinuse(p, psize, next); |
goto postaction; |
} |
} |
else |
goto erroraction; |
} |
} |
|
if (RTCHECK(ok_next(p, next) && ok_pinuse(next))) { |
if (!cinuse(next)) { /* consolidate forward */ |
if (next == fm->top) { |
size_t tsize = fm->topsize += psize; |
fm->top = p; |
p->head = tsize | PINUSE_BIT; |
if (p == fm->dv) { |
fm->dv = 0; |
fm->dvsize = 0; |
} |
if (should_trim(fm, tsize)) |
sys_trim(fm, 0); |
goto postaction; |
} |
else if (next == fm->dv) { |
size_t dsize = fm->dvsize += psize; |
fm->dv = p; |
set_size_and_pinuse_of_free_chunk(p, dsize); |
goto postaction; |
} |
else { |
size_t nsize = chunksize(next); |
psize += nsize; |
unlink_chunk(fm, next, nsize); |
set_size_and_pinuse_of_free_chunk(p, psize); |
if (p == fm->dv) { |
fm->dvsize = psize; |
goto postaction; |
} |
} |
} |
else |
set_free_with_pinuse(p, psize, next); |
insert_chunk(fm, p, psize); |
check_free_chunk(fm, p); |
goto postaction; |
} |
} |
erroraction: |
USAGE_ERROR_ACTION(fm, p); |
postaction: |
POSTACTION(fm); |
} |
} |
} |
|
void* mspace_calloc(mspace msp, size_t n_elements, size_t elem_size) { |
void* mem; |
size_t req = 0; |
mstate ms = (mstate)msp; |
if (!ok_magic(ms)) { |
USAGE_ERROR_ACTION(ms,ms); |
return 0; |
} |
if (n_elements != 0) { |
req = n_elements * elem_size; |
if (((n_elements | elem_size) & ~(size_t)0xffff) && |
(req / n_elements != elem_size)) |
req = MAX_SIZE_T; /* force downstream failure on overflow */ |
} |
mem = internal_malloc(ms, req); |
if (mem != 0 && calloc_must_clear(mem2chunk(mem))) |
memset(mem, 0, req); |
return mem; |
} |
|
void* mspace_realloc(mspace msp, void* oldmem, size_t bytes) { |
if (oldmem == 0) |
return mspace_malloc(msp, bytes); |
#ifdef REALLOC_ZERO_BYTES_FREES |
if (bytes == 0) { |
mspace_free(msp, oldmem); |
return 0; |
} |
#endif /* REALLOC_ZERO_BYTES_FREES */ |
else { |
#if FOOTERS |
mchunkptr p = mem2chunk(oldmem); |
mstate ms = get_mstate_for(p); |
#else /* FOOTERS */ |
mstate ms = (mstate)msp; |
#endif /* FOOTERS */ |
if (!ok_magic(ms)) { |
USAGE_ERROR_ACTION(ms,ms); |
return 0; |
} |
return internal_realloc(ms, oldmem, bytes); |
} |
} |
|
void* mspace_memalign(mspace msp, size_t alignment, size_t bytes) { |
mstate ms = (mstate)msp; |
if (!ok_magic(ms)) { |
USAGE_ERROR_ACTION(ms,ms); |
return 0; |
} |
return internal_memalign(ms, alignment, bytes); |
} |
|
void** mspace_independent_calloc(mspace msp, size_t n_elements, |
size_t elem_size, void* chunks[]) { |
size_t sz = elem_size; /* serves as 1-element array */ |
mstate ms = (mstate)msp; |
if (!ok_magic(ms)) { |
USAGE_ERROR_ACTION(ms,ms); |
return 0; |
} |
return ialloc(ms, n_elements, &sz, 3, chunks); |
} |
|
void** mspace_independent_comalloc(mspace msp, size_t n_elements, |
size_t sizes[], void* chunks[]) { |
mstate ms = (mstate)msp; |
if (!ok_magic(ms)) { |
USAGE_ERROR_ACTION(ms,ms); |
return 0; |
} |
return ialloc(ms, n_elements, sizes, 0, chunks); |
} |
|
int mspace_trim(mspace msp, size_t pad) { |
int result = 0; |
mstate ms = (mstate)msp; |
if (ok_magic(ms)) { |
if (!PREACTION(ms)) { |
result = sys_trim(ms, pad); |
POSTACTION(ms); |
} |
} |
else { |
USAGE_ERROR_ACTION(ms,ms); |
} |
return result; |
} |
|
void mspace_malloc_stats(mspace msp) { |
mstate ms = (mstate)msp; |
if (ok_magic(ms)) { |
internal_malloc_stats(ms); |
} |
else { |
USAGE_ERROR_ACTION(ms,ms); |
} |
} |
|
size_t mspace_footprint(mspace msp) { |
size_t result; |
mstate ms = (mstate)msp; |
if (ok_magic(ms)) { |
result = ms->footprint; |
} |
USAGE_ERROR_ACTION(ms,ms); |
return result; |
} |
|
|
size_t mspace_max_footprint(mspace msp) { |
size_t result; |
mstate ms = (mstate)msp; |
if (ok_magic(ms)) { |
result = ms->max_footprint; |
} |
USAGE_ERROR_ACTION(ms,ms); |
return result; |
} |
|
|
#if !NO_MALLINFO |
struct mallinfo mspace_mallinfo(mspace msp) { |
mstate ms = (mstate)msp; |
if (!ok_magic(ms)) { |
USAGE_ERROR_ACTION(ms,ms); |
} |
return internal_mallinfo(ms); |
} |
#endif /* NO_MALLINFO */ |
|
int mspace_mallopt(int param_number, int value) { |
return change_mparam(param_number, value); |
} |
|
#endif /* MSPACES */ |
|
/* -------------------- Alternative MORECORE functions ------------------- */ |
|
/* |
Guidelines for creating a custom version of MORECORE: |
|
* For best performance, MORECORE should allocate in multiples of pagesize. |
* MORECORE may allocate more memory than requested. (Or even less, |
but this will usually result in a malloc failure.) |
* MORECORE must not allocate memory when given argument zero, but |
instead return one past the end address of memory from previous |
nonzero call. |
* For best performance, consecutive calls to MORECORE with positive |
arguments should return increasing addresses, indicating that |
space has been contiguously extended. |
* Even though consecutive calls to MORECORE need not return contiguous |
addresses, it must be OK for malloc'ed chunks to span multiple |
regions in those cases where they do happen to be contiguous. |
* MORECORE need not handle negative arguments -- it may instead |
just return MFAIL when given negative arguments. |
Negative arguments are always multiples of pagesize. MORECORE |
must not misinterpret negative args as large positive unsigned |
args. You can suppress all such calls from even occurring by defining |
MORECORE_CANNOT_TRIM, |
|
As an example alternative MORECORE, here is a custom allocator |
kindly contributed for pre-OSX macOS. It uses virtually but not |
necessarily physically contiguous non-paged memory (locked in, |
present and won't get swapped out). You can use it by uncommenting |
this section, adding some #includes, and setting up the appropriate |
defines above: |
|
#define MORECORE osMoreCore |
|
There is also a shutdown routine that should somehow be called for |
cleanup upon program exit. |
|
#define MAX_POOL_ENTRIES 100 |
#define MINIMUM_MORECORE_SIZE (64 * 1024U) |
static int next_os_pool; |
void *our_os_pools[MAX_POOL_ENTRIES]; |
|
void *osMoreCore(int size) |
{ |
void *ptr = 0; |
static void *sbrk_top = 0; |
|
if (size > 0) |
{ |
if (size < MINIMUM_MORECORE_SIZE) |
size = MINIMUM_MORECORE_SIZE; |
if (CurrentExecutionLevel() == kTaskLevel) |
ptr = PoolAllocateResident(size + RM_PAGE_SIZE, 0); |
if (ptr == 0) |
{ |
return (void *) MFAIL; |
} |
// save ptrs so they can be freed during cleanup |
our_os_pools[next_os_pool] = ptr; |
next_os_pool++; |
ptr = (void *) ((((size_t) ptr) + RM_PAGE_MASK) & ~RM_PAGE_MASK); |
sbrk_top = (char *) ptr + size; |
return ptr; |
} |
else if (size < 0) |
{ |
// we don't currently support shrink behavior |
return (void *) MFAIL; |
} |
else |
{ |
return sbrk_top; |
} |
} |
|
// cleanup any allocated memory pools |
// called as last thing before shutting down driver |
|
void osCleanupMem(void) |
{ |
void **ptr; |
|
for (ptr = our_os_pools; ptr < &our_os_pools[MAX_POOL_ENTRIES]; ptr++) |
if (*ptr) |
{ |
PoolDeallocate(*ptr); |
*ptr = 0; |
} |
} |
|
*/ |
|
|
/* ----------------------------------------------------------------------- |
History: |
V2.8.3 Thu Sep 22 11:16:32 2005 Doug Lea (dl at gee) |
* Add max_footprint functions |
* Ensure all appropriate literals are size_t |
* Fix conditional compilation problem for some #define settings |
* Avoid concatenating segments with the one provided |
in create_mspace_with_base |
* Rename some variables to avoid compiler shadowing warnings |
* Use explicit lock initialization. |
* Better handling of sbrk interference. |
* Simplify and fix segment insertion, trimming and mspace_destroy |
* Reinstate REALLOC_ZERO_BYTES_FREES option from 2.7.x |
* Thanks especially to Dennis Flanagan for help on these. |
|
V2.8.2 Sun Jun 12 16:01:10 2005 Doug Lea (dl at gee) |
* Fix memalign brace error. |
|
V2.8.1 Wed Jun 8 16:11:46 2005 Doug Lea (dl at gee) |
* Fix improper #endif nesting in C++ |
* Add explicit casts needed for C++ |
|
V2.8.0 Mon May 30 14:09:02 2005 Doug Lea (dl at gee) |
* Use trees for large bins |
* Support mspaces |
* Use segments to unify sbrk-based and mmap-based system allocation, |
removing need for emulation on most platforms without sbrk. |
* Default safety checks |
* Optional footer checks. Thanks to William Robertson for the idea. |
* Internal code refactoring |
* Incorporate suggestions and platform-specific changes. |
Thanks to Dennis Flanagan, Colin Plumb, Niall Douglas, |
Aaron Bachmann, Emery Berger, and others. |
* Speed up non-fastbin processing enough to remove fastbins. |
* Remove useless cfree() to avoid conflicts with other apps. |
* Remove internal memcpy, memset. Compilers handle builtins better. |
* Remove some options that no one ever used and rename others. |
|
V2.7.2 Sat Aug 17 09:07:30 2002 Doug Lea (dl at gee) |
* Fix malloc_state bitmap array misdeclaration |
|
V2.7.1 Thu Jul 25 10:58:03 2002 Doug Lea (dl at gee) |
* Allow tuning of FIRST_SORTED_BIN_SIZE |
* Use PTR_UINT as type for all ptr->int casts. Thanks to John Belmonte. |
* Better detection and support for non-contiguousness of MORECORE. |
Thanks to Andreas Mueller, Conal Walsh, and Wolfram Gloger |
* Bypass most of malloc if no frees. Thanks To Emery Berger. |
* Fix freeing of old top non-contiguous chunk im sysmalloc. |
* Raised default trim and map thresholds to 256K. |
* Fix mmap-related #defines. Thanks to Lubos Lunak. |
* Fix copy macros; added LACKS_FCNTL_H. Thanks to Neal Walfield. |
* Branch-free bin calculation |
* Default trim and mmap thresholds now 256K. |
|
V2.7.0 Sun Mar 11 14:14:06 2001 Doug Lea (dl at gee) |
* Introduce independent_comalloc and independent_calloc. |
Thanks to Michael Pachos for motivation and help. |
* Make optional .h file available |
* Allow > 2GB requests on 32bit systems. |
* new WIN32 sbrk, mmap, munmap, lock code from <Walter@GeNeSys-e.de>. |
Thanks also to Andreas Mueller <a.mueller at paradatec.de>, |
and Anonymous. |
* Allow override of MALLOC_ALIGNMENT (Thanks to Ruud Waij for |
helping test this.) |
* memalign: check alignment arg |
* realloc: don't try to shift chunks backwards, since this |
leads to more fragmentation in some programs and doesn't |
seem to help in any others. |
* Collect all cases in malloc requiring system memory into sysmalloc |
* Use mmap as backup to sbrk |
* Place all internal state in malloc_state |
* Introduce fastbins (although similar to 2.5.1) |
* Many minor tunings and cosmetic improvements |
* Introduce USE_PUBLIC_MALLOC_WRAPPERS, USE_MALLOC_LOCK |
* Introduce MALLOC_FAILURE_ACTION, MORECORE_CONTIGUOUS |
Thanks to Tony E. Bennett <tbennett@nvidia.com> and others. |
* Include errno.h to support default failure action. |
|
V2.6.6 Sun Dec 5 07:42:19 1999 Doug Lea (dl at gee) |
* return null for negative arguments |
* Added Several WIN32 cleanups from Martin C. Fong <mcfong at yahoo.com> |
* Add 'LACKS_SYS_PARAM_H' for those systems without 'sys/param.h' |
(e.g. WIN32 platforms) |
* Cleanup header file inclusion for WIN32 platforms |
* Cleanup code to avoid Microsoft Visual C++ compiler complaints |
* Add 'USE_DL_PREFIX' to quickly allow co-existence with existing |
memory allocation routines |
* Set 'malloc_getpagesize' for WIN32 platforms (needs more work) |
* Use 'assert' rather than 'ASSERT' in WIN32 code to conform to |
usage of 'assert' in non-WIN32 code |
* Improve WIN32 'sbrk()' emulation's 'findRegion()' routine to |
avoid infinite loop |
* Always call 'fREe()' rather than 'free()' |
|
V2.6.5 Wed Jun 17 15:57:31 1998 Doug Lea (dl at gee) |
* Fixed ordering problem with boundary-stamping |
|
V2.6.3 Sun May 19 08:17:58 1996 Doug Lea (dl at gee) |
* Added pvalloc, as recommended by H.J. Liu |
* Added 64bit pointer support mainly from Wolfram Gloger |
* Added anonymously donated WIN32 sbrk emulation |
* Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen |
* malloc_extend_top: fix mask error that caused wastage after |
foreign sbrks |
* Add linux mremap support code from HJ Liu |
|
V2.6.2 Tue Dec 5 06:52:55 1995 Doug Lea (dl at gee) |
* Integrated most documentation with the code. |
* Add support for mmap, with help from |
Wolfram Gloger (Gloger@lrz.uni-muenchen.de). |
* Use last_remainder in more cases. |
* Pack bins using idea from colin@nyx10.cs.du.edu |
* Use ordered bins instead of best-fit threshhold |
* Eliminate block-local decls to simplify tracing and debugging. |
* Support another case of realloc via move into top |
* Fix error occuring when initial sbrk_base not word-aligned. |
* Rely on page size for units instead of SBRK_UNIT to |
avoid surprises about sbrk alignment conventions. |
* Add mallinfo, mallopt. Thanks to Raymond Nijssen |
(raymond@es.ele.tue.nl) for the suggestion. |
* Add `pad' argument to malloc_trim and top_pad mallopt parameter. |
* More precautions for cases where other routines call sbrk, |
courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de). |
* Added macros etc., allowing use in linux libc from |
H.J. Lu (hjl@gnu.ai.mit.edu) |
* Inverted this history list |
|
V2.6.1 Sat Dec 2 14:10:57 1995 Doug Lea (dl at gee) |
* Re-tuned and fixed to behave more nicely with V2.6.0 changes. |
* Removed all preallocation code since under current scheme |
the work required to undo bad preallocations exceeds |
the work saved in good cases for most test programs. |
* No longer use return list or unconsolidated bins since |
no scheme using them consistently outperforms those that don't |
given above changes. |
* Use best fit for very large chunks to prevent some worst-cases. |
* Added some support for debugging |
|
V2.6.0 Sat Nov 4 07:05:23 1995 Doug Lea (dl at gee) |
* Removed footers when chunks are in use. Thanks to |
Paul Wilson (wilson@cs.texas.edu) for the suggestion. |
|
V2.5.4 Wed Nov 1 07:54:51 1995 Doug Lea (dl at gee) |
* Added malloc_trim, with help from Wolfram Gloger |
(wmglo@Dent.MED.Uni-Muenchen.DE). |
|
V2.5.3 Tue Apr 26 10:16:01 1994 Doug Lea (dl at g) |
|
V2.5.2 Tue Apr 5 16:20:40 1994 Doug Lea (dl at g) |
* realloc: try to expand in both directions |
* malloc: swap order of clean-bin strategy; |
* realloc: only conditionally expand backwards |
* Try not to scavenge used bins |
* Use bin counts as a guide to preallocation |
* Occasionally bin return list chunks in first scan |
* Add a few optimizations from colin@nyx10.cs.du.edu |
|
V2.5.1 Sat Aug 14 15:40:43 1993 Doug Lea (dl at g) |
* faster bin computation & slightly different binning |
* merged all consolidations to one part of malloc proper |
(eliminating old malloc_find_space & malloc_clean_bin) |
* Scan 2 returns chunks (not just 1) |
* Propagate failure in realloc if malloc returns 0 |
* Add stuff to allow compilation on non-ANSI compilers |
from kpv@research.att.com |
|
V2.5 Sat Aug 7 07:41:59 1993 Doug Lea (dl at g.oswego.edu) |
* removed potential for odd address access in prev_chunk |
* removed dependency on getpagesize.h |
* misc cosmetics and a bit more internal documentation |
* anticosmetics: mangled names in macros to evade debugger strangeness |
* tested on sparc, hp-700, dec-mips, rs6000 |
with gcc & native cc (hp, dec only) allowing |
Detlefs & Zorn comparison study (in SIGPLAN Notices.) |
|
Trial version Fri Aug 28 13:14:29 1992 Doug Lea (dl at g.oswego.edu) |
* Based loosely on libg++-1.2X malloc. (It retains some of the overall |
structure of old version, but most details differ.) |
|
*/ |