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/*
* 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 <dirent.h>
#include <assert.h>
#include <sys/types.h>
#include <libadt/hash_table.h>
#include <as.h>
#define min(a, b) ((a) < (b) ? (a) : (b))
#define max(a, b) ((a) > (b) ? (a) : (b))
#define PLB_GET_CHAR(i) (tmpfs_reg.plb_ro[(i) % PLB_SIZE])
#define DENTRIES_BUCKETS 256
#define TMPFS_GET_INDEX(x) (((tmpfs_dentry_t *)(x))->index)
#define TMPFS_GET_LNKCNT(x) 1
/*
* Hash table of all directory entries.
*/
hash_table_t dentries;
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
};
unsigned tmpfs_next_index = 1;
static void tmpfs_dentry_initialize(tmpfs_dentry_t *dentry)
{
dentry->index = 0;
dentry->parent = NULL;
dentry->sibling = NULL;
dentry->child = NULL;
dentry->name = NULL;
dentry->type = TMPFS_NONE;
dentry->size = 0;
dentry->data = NULL;
link_initialize(&dentry->dh_link);
}
/*
* 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;
static bool tmpfs_init(void)
{
if (!hash_table_create(&dentries, DENTRIES_BUCKETS, 1, &dentries_ops))
return false;
root = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
if (!root)
return false;
tmpfs_dentry_initialize(root);
root->index = tmpfs_next_index++;
root->name = "";
root->type = TMPFS_DIRECTORY;
hash_table_insert(&dentries, &root->index, &root->dh_link);
return true;
}
/** Compare one component of path to a directory entry.
*
* @param nodep Node to compare the path component with.
* @param component Array of characters holding component name.
*
* @return True on match, false otherwise.
*/
static bool match_component(void *nodep, const char *component)
{
tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
return !strcmp(dentry->name, component);
}
static void *create_node(void *nodep,
const char *component, int lflag)
{
tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
assert(dentry->type == TMPFS_DIRECTORY);
assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));
tmpfs_dentry_t *node = malloc(sizeof(tmpfs_dentry_t));
if (!node)
return NULL;
size_t len = strlen(component);
char *name = malloc(len + 1);
if (!name) {
free(node);
return NULL;
}
strcpy(name, component);
tmpfs_dentry_initialize(node);
node->index = tmpfs_next_index++;
node->name = name;
node->parent = dentry;
if (lflag & L_DIRECTORY)
node->type = TMPFS_DIRECTORY;
else
node->type = TMPFS_FILE;
/* Insert the new node into the namespace. */
if (dentry->child) {
tmpfs_dentry_t *tmp = dentry->child;
while (tmp->sibling)
tmp = tmp->sibling;
tmp->sibling = node;
} else {
dentry->child = node;
}
/* Insert the new node into the dentry hash table. */
hash_table_insert(&dentries, &node->index, &node->dh_link);
return (void *) node;
}
static int destroy_component(void *nodeptr)
{
tmpfs_dentry_t *dentry = (tmpfs_dentry_t *)nodeptr;
if (dentry->child)
return ENOTEMPTY;
if (!dentry->parent)
return EBUSY;
if (dentry->parent->child == dentry) {
dentry->parent->child = dentry->sibling;
} else {
/* TODO: consider doubly linked list for organizing siblings. */
tmpfs_dentry_t *tmp = dentry->parent->child;
while (tmp->sibling != dentry)
tmp = tmp->sibling;
tmp->sibling = dentry->sibling;
}
return EOK;
}
void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
{
unsigned next = IPC_GET_ARG1(*request);
unsigned last = IPC_GET_ARG2(*request);
int dev_handle = IPC_GET_ARG3(*request);
int lflag = IPC_GET_ARG4(*request);
if (last < next)
last += PLB_SIZE;
/*
* Initialize TMPFS.
*/
if (!root && !tmpfs_init()) {
ipc_answer_0(rid, ENOMEM);
return;
}
tmpfs_dentry_t *dtmp = root->child;
tmpfs_dentry_t *dcur = root;
if (PLB_GET_CHAR(next) == '/')
next++; /* eat slash */
char component[NAME_MAX + 1];
int len = 0;
while (dtmp && next <= last) {
/* collect the component */
if (PLB_GET_CHAR(next) != '/') {
if (len + 1 == NAME_MAX) {
/* comopnent length overflow */
ipc_answer_0(rid, ENAMETOOLONG);
return;
}
component[len++] = PLB_GET_CHAR(next);
next++; /* process next character */
if (next <= last)
continue;
}
assert(len);
component[len] = '\0';
next++; /* eat slash */
len = 0;
/* match the component */
while (dtmp && !match_component(dtmp, component))
dtmp = dtmp->sibling;
/* handle miss: match amongst siblings */
if (!dtmp) {
if ((next > last) && (lflag & L_CREATE)) {
/* no components left and L_CREATE specified */
if (dcur->type != TMPFS_DIRECTORY) {
ipc_answer_0(rid, ENOTDIR);
return;
}
void *nodep = create_node(dcur,
component, lflag);
if (nodep) {
ipc_answer_5(rid, EOK,
tmpfs_reg.fs_handle, dev_handle,
TMPFS_GET_INDEX(nodep), 0,
TMPFS_GET_LNKCNT(nodep));
} else {
ipc_answer_0(rid, ENOSPC);
}
return;
}
ipc_answer_0(rid, ENOENT);
return;
}
/* descend one level */
dcur = dtmp;
dtmp = dtmp->child;
}
/* handle miss: excessive components */
if (!dtmp && next <= last) {
if (lflag & L_CREATE) {
if (dcur->type != TMPFS_DIRECTORY) {
ipc_answer_0(rid, ENOTDIR);
return;
}
/* collect next component */
while (next <= last) {
if (PLB_GET_CHAR(next) == '/') {
/* more than one component */
ipc_answer_0(rid, ENOENT);
return;
}
if (len + 1 == NAME_MAX) {
/* component length overflow */
ipc_answer_0(rid, ENAMETOOLONG);
return;
}
component[len++] = PLB_GET_CHAR(next);
next++; /* process next character */
}
assert(len);
component[len] = '\0';
len = 0;
void *nodep = create_node(dcur, component, lflag);
if (nodep) {
ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle,
dev_handle, TMPFS_GET_INDEX(nodep), 0,
TMPFS_GET_LNKCNT(nodep));
} else {
ipc_answer_0(rid, ENOSPC);
}
return;
}
ipc_answer_0(rid, ENOENT);
return;
}
/* handle hit */
if (lflag & L_DESTROY) {
int res = destroy_component(dcur);
unsigned lnkcnt = (res == EOK) ? 0 : TMPFS_GET_LNKCNT(dcur);
ipc_answer_5(rid, (ipcarg_t)res, tmpfs_reg.fs_handle,
dev_handle, dcur->index, dcur->size, lnkcnt);
return;
}
if ((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) {
ipc_answer_0(rid, EEXIST);
return;
}
if ((lflag & L_FILE) && (dcur->type != TMPFS_FILE)) {
ipc_answer_0(rid, EISDIR);
return;
}
if ((lflag & L_DIRECTORY) && (dcur->type != TMPFS_DIRECTORY)) {
ipc_answer_0(rid, ENOTDIR);
return;
}
ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle, dev_handle, dcur->index,
dcur->size, TMPFS_GET_LNKCNT(dcur));
}
void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
{
int dev_handle = IPC_GET_ARG1(*request);
unsigned long index = IPC_GET_ARG2(*request);
off_t pos = IPC_GET_ARG3(*request);
/*
* Lookup the respective dentry.
*/
link_t *hlp;
hlp = hash_table_find(&dentries, &index);
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 = dentry->child;
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;
}
(void) ipc_data_read_finalize(callid, cur->name,
strlen(cur->name) + 1);
bytes = 1;
}
/*
* Answer the VFS_READ call.
*/
ipc_answer_1(rid, EOK, bytes);
}
void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
{
int dev_handle = IPC_GET_ARG1(*request);
unsigned long index = IPC_GET_ARG2(*request);
off_t pos = IPC_GET_ARG3(*request);
/*
* Lookup the respective dentry.
*/
link_t *hlp;
hlp = hash_table_find(&dentries, &index);
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)
{
int dev_handle = IPC_GET_ARG1(*request);
unsigned long index = IPC_GET_ARG2(*request);
size_t size = IPC_GET_ARG3(*request);
/*
* Lookup the respective dentry.
*/
link_t *hlp;
hlp = hash_table_find(&dentries, &index);
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_free(ipc_callid_t rid, ipc_call_t *request)
{
int dev_handle = IPC_GET_ARG1(*request);
unsigned long index = IPC_GET_ARG2(*request);
link_t *hlp;
hlp = hash_table_find(&dentries, &index);
if (!hlp) {
ipc_answer_0(rid, ENOENT);
return;
}
tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
dh_link);
assert(!dentry->parent);
assert(!dentry->child);
assert(!dentry->sibling);
hash_table_remove(&dentries, &index, 1);
if (dentry->type == TMPFS_FILE)
free(dentry->data);
free(dentry->name);
free(dentry);
ipc_answer_0(rid, EOK);
}
/**
* @}
*/