/*
* Copyright (c) 2008 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup fs
* @{
*/
/**
* @file tmpfs_ops.c
* @brief Implementation of VFS operations for the TMPFS file system
* server.
*/
#include "tmpfs.h"
#include "../../vfs/vfs.h"
#include <ipc/ipc.h>
#include <async.h>
#include <errno.h>
#include <atomic.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <assert.h>
#include <sys/types.h>
#include <libadt/hash_table.h>
#include <as.h>
#include <libfs.h>
#define min(a, b) ((a) < (b) ? (a) : (b))
#define max(a, b) ((a) > (b) ? (a) : (b))
#define DENTRIES_BUCKETS 256
#define NAMES_BUCKETS 4
/*
* For now, we don't distinguish between different dev_handles/instances. All
* requests resolve to the only instance, rooted in the following variable.
*/
static tmpfs_dentry_t *root;
#define TMPFS_DEV 0 /**< Dummy device handle for TMPFS */
/*
* Implementation of the libfs interface.
*/
/* Forward declarations of static functions. */
static void *tmpfs_match(void *, const char *);
static void *tmpfs_node_get(dev_handle_t, fs_index_t);
static void tmpfs_node_put(void *);
static void *tmpfs_create_node(dev_handle_t, int);
static int tmpfs_link_node(void *, void *, const char *);
static int tmpfs_unlink_node(void *, void *);
static int tmpfs_destroy_node(void *);
/* Implementation of helper functions. */
static fs_index_t tmpfs_index_get(void *nodep)
{
return ((tmpfs_dentry_t *) nodep)->index;
}
static size_t tmpfs_size_get(void *nodep)
{
return ((tmpfs_dentry_t *) nodep)->size;
}
static unsigned tmpfs_lnkcnt_get(void *nodep)
{
return ((tmpfs_dentry_t *) nodep)->lnkcnt;
}
static bool tmpfs_has_children(void *nodep)
{
return ((tmpfs_dentry_t *) nodep)->child != NULL;
}
static void *tmpfs_root_get(dev_handle_t dev_handle)
{
return root;
}
static char tmpfs_plb_get_char(unsigned pos)
{
return tmpfs_reg.plb_ro[pos % PLB_SIZE];
}
static bool tmpfs_is_directory(void *nodep)
{
return ((tmpfs_dentry_t *) nodep)->type == TMPFS_DIRECTORY;
}
static bool tmpfs_is_file(void *nodep)
{
return ((tmpfs_dentry_t *) nodep)->type == TMPFS_FILE;
}
/** libfs operations */
libfs_ops_t tmpfs_libfs_ops = {
.match = tmpfs_match,
.node_get = tmpfs_node_get,
.node_put = tmpfs_node_put,
.create = tmpfs_create_node,
.destroy = tmpfs_destroy_node,
.link = tmpfs_link_node,
.unlink = tmpfs_unlink_node,
.index_get = tmpfs_index_get,
.size_get = tmpfs_size_get,
.lnkcnt_get = tmpfs_lnkcnt_get,
.has_children = tmpfs_has_children,
.root_get = tmpfs_root_get,
.plb_get_char = tmpfs_plb_get_char,
.is_directory = tmpfs_is_directory,
.is_file = tmpfs_is_file
};
/** Hash table of all directory entries. */
hash_table_t dentries;
/* Implementation of hash table interface for the dentries hash table. */
static hash_index_t dentries_hash(unsigned long *key)
{
return *key % DENTRIES_BUCKETS;
}
static int dentries_compare(unsigned long *key, hash_count_t keys,
link_t *item)
{
tmpfs_dentry_t *dentry = hash_table_get_instance(item, tmpfs_dentry_t,
dh_link);
return dentry->index == *key;
}
static void dentries_remove_callback(link_t *item)
{
}
/** TMPFS dentries hash table operations. */
hash_table_operations_t dentries_ops = {
.hash = dentries_hash,
.compare = dentries_compare,
.remove_callback = dentries_remove_callback
};
fs_index_t tmpfs_next_index = 1;
typedef struct {
char *name;
tmpfs_dentry_t *parent;
link_t link;
} tmpfs_name_t;
/* Implementation of hash table interface for the names hash table. */
static hash_index_t names_hash(unsigned long *key)
{
tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) *key;
return dentry->index % NAMES_BUCKETS;
}
static int names_compare(unsigned long *key, hash_count_t keys, link_t *item)
{
tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) *key;
tmpfs_name_t *namep = hash_table_get_instance(item, tmpfs_name_t,
link);
return dentry == namep->parent;
}
static void names_remove_callback(link_t *item)
{
tmpfs_name_t *namep = hash_table_get_instance(item, tmpfs_name_t,
link);
}
/** TMPFS node names hash table operations. */
static hash_table_operations_t names_ops = {
.hash = names_hash,
.compare = names_compare,
.remove_callback = names_remove_callback
};
static void tmpfs_name_initialize(tmpfs_name_t *namep)
{
namep->name = NULL;
namep->parent = NULL;
link_initialize(&namep->link);
}
static bool tmpfs_dentry_initialize(tmpfs_dentry_t *dentry)
{
dentry->index = 0;
dentry->sibling = NULL;
dentry->child = NULL;
dentry->type = TMPFS_NONE;
dentry->lnkcnt = 0;
dentry->size = 0;
dentry->data = NULL;
link_initialize(&dentry->dh_link);
return (bool)hash_table_create(&dentry->names, NAMES_BUCKETS, 1,
&names_ops);
}
static bool tmpfs_init(void)
{
if (!hash_table_create(&dentries, DENTRIES_BUCKETS, 1, &dentries_ops))
return false;
root = (tmpfs_dentry_t *) tmpfs_create_node(TMPFS_DEV, L_DIRECTORY);
if (!root) {
hash_table_destroy(&dentries);
return false;
}
root->lnkcnt = 0; /* FS root is not linked */
return true;
}
/** Compare one component of path to a directory entry.
*
* @param parentp Pointer to node from which we descended.
* @param childp Pointer to node to compare the path component with.
* @param component Array of characters holding component name.
*
* @return True on match, false otherwise.
*/
static bool
tmpfs_match_one(tmpfs_dentry_t *parentp, tmpfs_dentry_t *childp,
const char *component)
{
unsigned long key = (unsigned long) parentp;
link_t *hlp = hash_table_find(&childp->names, &key);
tmpfs_name_t *namep = hash_table_get_instance(hlp, tmpfs_name_t, link);
return !strcmp(namep
->name
, component
); }
void *tmpfs_match(void *prnt, const char *component)
{
tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
tmpfs_dentry_t *childp = parentp->child;
while (childp && !tmpfs_match_one(parentp, childp, component))
childp = childp->sibling;
return (void *) childp;
}
void *
tmpfs_node_get(dev_handle_t dev_handle, fs_index_t index)
{
unsigned long key = index;
link_t *lnk = hash_table_find(&dentries, &key);
if (!lnk)
return NULL;
return hash_table_get_instance(lnk, tmpfs_dentry_t, dh_link);
}
void tmpfs_node_put(void *node)
{
/* nothing to do */
}
void *tmpfs_create_node(dev_handle_t dev_handle, int lflag)
{
assert((lflag
& L_FILE
) ^ (lflag
& L_DIRECTORY
));
tmpfs_dentry_t
*node
= malloc(sizeof(tmpfs_dentry_t
)); if (!node)
return NULL;
if (!tmpfs_dentry_initialize(node)) {
return NULL;
}
node->index = tmpfs_next_index++;
if (lflag & L_DIRECTORY)
node->type = TMPFS_DIRECTORY;
else
node->type = TMPFS_FILE;
/* Insert the new node into the dentry hash table. */
unsigned long key = node->index;
hash_table_insert(&dentries, &key, &node->dh_link);
return (void *) node;
}
int tmpfs_link_node(void *prnt, void *chld, const char *nm)
{
tmpfs_dentry_t *parentp = (tmpfs_dentry_t *) prnt;
tmpfs_dentry_t *childp = (tmpfs_dentry_t *) chld;
assert(parentp
->type
== TMPFS_DIRECTORY
);
tmpfs_name_t
*namep
= malloc(sizeof(tmpfs_name_t
)); if (!namep)
return ENOMEM;
tmpfs_name_initialize(namep);
namep
->name
= malloc(len
+ 1); if (!namep->name) {
return ENOMEM;
}
namep->parent = parentp;
childp->lnkcnt++;
unsigned long key = (unsigned long) parentp;
hash_table_insert(&childp->names, &key, &namep->link);
/* Insert the new node into the namespace. */
if (parentp->child) {
tmpfs_dentry_t *tmp = parentp->child;
while (tmp->sibling)
tmp = tmp->sibling;
tmp->sibling = childp;
} else {
parentp->child = childp;
}
return EOK;
}
int tmpfs_unlink_node(void *prnt, void *chld)
{
tmpfs_dentry_t *parentp = (tmpfs_dentry_t *)prnt;
tmpfs_dentry_t *childp = (tmpfs_dentry_t *)chld;
if (!parentp)
return EBUSY;
if (childp->child)
return ENOTEMPTY;
if (parentp->child == childp) {
parentp->child = childp->sibling;
} else {
/* TODO: consider doubly linked list for organizing siblings. */
tmpfs_dentry_t *tmp = parentp->child;
while (tmp->sibling != childp)
tmp = tmp->sibling;
tmp->sibling = childp->sibling;
}
childp->sibling = NULL;
unsigned long key = (unsigned long) parentp;
hash_table_remove(&childp->names, &key, 1);
childp->lnkcnt--;
return EOK;
}
int tmpfs_destroy_node(void *nodep)
{
tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
unsigned long key = dentry->index;
hash_table_remove(&dentries, &key, 1);
hash_table_destroy(&dentry->names);
if (dentry->type == TMPFS_FILE)
return EOK;
}
void tmpfs_mounted(ipc_callid_t rid, ipc_call_t *request)
{
dev_handle_t dev_handle = (dev_handle_t) IPC_GET_ARG1(*request);
/* Initialize TMPFS. */
if (!root && !tmpfs_init()) {
ipc_answer_0(rid, ENOMEM);
return;
}
if (dev_handle >= 0) {
if (tmpfs_restore(dev_handle))
ipc_answer_3(rid, EOK, root->index, root->size,
root->lnkcnt);
else
ipc_answer_0(rid, ELIMIT);
} else {
ipc_answer_3(rid, EOK, root->index, root->size, root->lnkcnt);
}
}
void tmpfs_mount(ipc_callid_t rid, ipc_call_t *request)
{
dev_handle_t mp_dev_handle = (dev_handle_t) IPC_GET_ARG1(*request);
fs_index_t mp_index = (fs_index_t) IPC_GET_ARG2(*request);
fs_handle_t mr_fs_handle = (fs_handle_t) IPC_GET_ARG3(*request);
dev_handle_t mr_dev_handle = (dev_handle_t) IPC_GET_ARG4(*request);
ipc_answer_0(rid, ENOTSUP);
}
void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
{
libfs_lookup(&tmpfs_libfs_ops, tmpfs_reg.fs_handle, rid, request);
}
void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
{
dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
off_t pos = (off_t)IPC_GET_ARG3(*request);
/*
* Lookup the respective dentry.
*/
link_t *hlp;
unsigned long key = index;
hlp = hash_table_find(&dentries, &key);
if (!hlp) {
ipc_answer_0(rid, ENOENT);
return;
}
tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
dh_link);
/*
* Receive the read request.
*/
ipc_callid_t callid;
size_t len;
if (!ipc_data_read_receive(&callid, &len)) {
ipc_answer_0(callid, EINVAL);
ipc_answer_0(rid, EINVAL);
return;
}
size_t bytes;
if (dentry->type == TMPFS_FILE) {
bytes = max(0, min(dentry->size - pos, len));
(void) ipc_data_read_finalize(callid, dentry->data + pos,
bytes);
} else {
int i;
tmpfs_dentry_t *cur;
assert(dentry
->type
== TMPFS_DIRECTORY
);
/*
* Yes, we really use O(n) algorithm here.
* If it bothers someone, it could be fixed by introducing a
* hash table.
*/
for (i = 0, cur = dentry->child; i < pos && cur; i++,
cur = cur->sibling)
;
if (!cur) {
ipc_answer_0(callid, ENOENT);
ipc_answer_1(rid, ENOENT, 0);
return;
}
unsigned long key = (unsigned long) dentry;
link_t *hlp = hash_table_find(&cur->names, &key);
tmpfs_name_t *namep = hash_table_get_instance(hlp, tmpfs_name_t,
link);
(void) ipc_data_read_finalize(callid, namep->name,
bytes = 1;
}
/*
* Answer the VFS_READ call.
*/
ipc_answer_1(rid, EOK, bytes);
}
void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
{
dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
off_t pos = (off_t)IPC_GET_ARG3(*request);
/*
* Lookup the respective dentry.
*/
link_t *hlp;
unsigned long key = index;
hlp = hash_table_find(&dentries, &key);
if (!hlp) {
ipc_answer_0(rid, ENOENT);
return;
}
tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
dh_link);
/*
* Receive the write request.
*/
ipc_callid_t callid;
size_t len;
if (!ipc_data_write_receive(&callid, &len)) {
ipc_answer_0(callid, EINVAL);
ipc_answer_0(rid, EINVAL);
return;
}
/*
* Check whether the file needs to grow.
*/
if (pos + len <= dentry->size) {
/* The file size is not changing. */
(void) ipc_data_write_finalize(callid, dentry->data + pos, len);
ipc_answer_2(rid, EOK, len, dentry->size);
return;
}
size_t delta = (pos + len) - dentry->size;
/*
* At this point, we are deliberately extremely straightforward and
* simply realloc the contents of the file on every write that grows the
* file. In the end, the situation might not be as bad as it may look:
* our heap allocator can save us and just grow the block whenever
* possible.
*/
void *newdata
= realloc(dentry
->data
, dentry
->size
+ delta
); if (!newdata) {
ipc_answer_0(callid, ENOMEM);
ipc_answer_2(rid, EOK, 0, dentry->size);
return;
}
/* Clear any newly allocated memory in order to emulate gaps. */
memset(newdata
+ dentry
->size
, 0, delta
); dentry->size += delta;
dentry->data = newdata;
(void) ipc_data_write_finalize(callid, dentry->data + pos, len);
ipc_answer_2(rid, EOK, len, dentry->size);
}
void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
{
dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
size_t size = (off_t)IPC_GET_ARG3(*request);
/*
* Lookup the respective dentry.
*/
link_t *hlp;
unsigned long key = index;
hlp = hash_table_find(&dentries, &key);
if (!hlp) {
ipc_answer_0(rid, ENOENT);
return;
}
tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
dh_link);
if (size == dentry->size) {
ipc_answer_0(rid, EOK);
return;
}
void *newdata
= realloc(dentry
->data
, size
); if (!newdata) {
ipc_answer_0(rid, ENOMEM);
return;
}
if (size > dentry->size) {
size_t delta = size - dentry->size;
memset(newdata
+ dentry
->size
, 0, delta
); }
dentry->size = size;
dentry->data = newdata;
ipc_answer_0(rid, EOK);
}
void tmpfs_destroy(ipc_callid_t rid, ipc_call_t *request)
{
dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
int rc;
link_t *hlp;
unsigned long key = index;
hlp = hash_table_find(&dentries, &key);
if (!hlp) {
ipc_answer_0(rid, ENOENT);
return;
}
tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
dh_link);
rc = tmpfs_destroy_node(dentry);
ipc_answer_0(rid, rc);
}
/**
* @}
*/