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/*
* Copyright (c) 2007 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 <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
/*
* 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);
/*
* This is only for debugging. Once we can create files and directories
* using VFS, we can get rid of this.
*/
tmpfs_dentry_t *d;
d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
if (!d) {
free(root);
root = NULL;
return false;
}
tmpfs_dentry_initialize(d);
d->index = tmpfs_next_index++;
root->child = d;
d->parent = root;
d->type = TMPFS_DIRECTORY;
d->name = "dir1";
hash_table_insert(&dentries, &d->index, &d->dh_link);
d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
if (!d) {
free(root->child);
free(root);
root = NULL;
return false;
}
tmpfs_dentry_initialize(d);
d->index = tmpfs_next_index++;
root->child->sibling = d;
d->parent = root;
d->type = TMPFS_DIRECTORY;
d->name = "dir2";
hash_table_insert(&dentries, &d->index, &d->dh_link);
d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
if (!d) {
free(root->child->sibling);
free(root->child);
free(root);
root = NULL;
return false;
}
tmpfs_dentry_initialize(d);
d->index = tmpfs_next_index++;
root->child->child = d;
d->parent = root->child;
d->type = TMPFS_FILE;
d->name = "file1";
d->data = "This is the contents of /dir1/file1.\n";
d->size = strlen(d->data);
hash_table_insert(&dentries, &d->index, &d->dh_link);
d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
if (!d) {
free(root->child->sibling);
free(root->child->child);
free(root->child);
free(root);
root = NULL;
return false;
}
tmpfs_dentry_initialize(d);
d->index = tmpfs_next_index++;
root->child->sibling->child = d;
d->parent = root->child->sibling;
d->type = TMPFS_FILE;
d->name = "file2";
d->data = "This is the contents of /dir2/file2.\n";
d->size = strlen(d->data);
hash_table_insert(&dentries, &d->index, &d->dh_link);
return true;
}
/** Compare one component of path to a directory entry.
*
* @param dentry Directory entry to compare the path component with.
* @param start Index into PLB where the path component starts.
* @param last Index of the last character of the path in PLB.
*
* @return Zero on failure or delta such that (index + delta) %
* PLB_SIZE points to the first unprocessed character in
* PLB which comprises the path.
*/
static unsigned match_path_component(tmpfs_dentry_t *dentry, unsigned start,
unsigned last)
{
int i, j;
size_t namelen;
namelen = strlen(dentry->name);
if (last < start)
last += PLB_SIZE;
for (i = 0, j = start; i < namelen && j <= last; i++, j++) {
if (dentry->name[i] != PLB_GET_CHAR(j))
return 0;
}
if (i != namelen)
return 0;
if (j < last && PLB_GET_CHAR(j) != '/')
return 0;
if (j == last)
return 0;
return (j - start);
}
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);
if (last < next)
last += PLB_SIZE;
if (!root && !tmpfs_init()) {
ipc_answer_0(rid, ENOMEM);
return;
}
tmpfs_dentry_t *dtmp = root->child;
tmpfs_dentry_t *dcur = root;
bool hit = true;
if (PLB_GET_CHAR(next) == '/')
next++; /* eat slash */
while (next <= last) {
unsigned delta;
hit = false;
do {
delta = match_path_component(dtmp, next, last);
if (!delta) {
dtmp = dtmp->sibling;
} else {
hit = true;
next += delta;
next++; /* eat slash */
dcur = dtmp;
dtmp = dtmp->child;
}
} while (delta == 0 && dtmp);
if (!hit) {
ipc_answer_3(rid, ENOENT, tmpfs_reg.fs_handle,
dev_handle, dcur->index);
return;
}
}
ipc_answer_3(rid, EOK, tmpfs_reg.fs_handle, dev_handle, dcur->index);
}
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 = max(0, min(dentry->size - pos, len));
(void) ipc_data_read_finalize(callid, dentry->data + pos, bytes);
/*
* 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_1(rid, EOK, len);
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_1(rid, EOK, 0);
return;
}
dentry->size += delta;
dentry->data = newdata;
(void) ipc_data_write_finalize(callid, dentry->data + pos, len);
ipc_answer_1(rid, EOK, len);
}
/**
* @}
*/