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/*
* Copyright (c) 2007 Travis Geiselbrecht
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files
* (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge,
* publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include <string.h>
#include <stdlib.h>
#include <debug.h>
#include <trace.h>
#include <err.h>
#include "ext2_priv.h"
#define LOCAL_TRACE 0
/* read in the dir, look for the entry */
static int ext2_dir_lookup(ext2_t *ext2, struct ext2_inode *dir_inode, const char *name, inodenum_t *inum)
{
uint file_blocknum;
int err;
uint8_t *buf;
size_t namelen = strlen(name);
if (!S_ISDIR(dir_inode->i_mode))
return ERR_NOT_DIR;
buf = malloc(EXT2_BLOCK_SIZE(ext2->sb));
file_blocknum = 0;
for (;;) {
/* read in the offset */
err = ext2_read_inode(ext2, dir_inode, buf, file_blocknum * EXT2_BLOCK_SIZE(ext2->sb), EXT2_BLOCK_SIZE(ext2->sb));
if (err <= 0) {
free(buf);
return -1;
}
/* walk through the directory entries, looking for the one that matches */
struct ext2_dir_entry_2 *ent;
uint pos = 0;
while (pos < EXT2_BLOCK_SIZE(ext2->sb)) {
ent = (struct ext2_dir_entry_2 *)&buf[pos];
LTRACEF("ent %d:%d: inode 0x%x, reclen %d, namelen %d\n",
file_blocknum, pos, LE32(ent->inode), LE16(ent->rec_len), ent->name_len/* , ent->name*/);
/* sanity check the record length */
if (LE16(ent->rec_len) == 0)
break;
if (ent->name_len == namelen && memcmp(name, ent->name, ent->name_len) == 0) {
// match
*inum = LE32(ent->inode);
LTRACEF("match: inode %d\n", *inum);
free(buf);
return 1;
}
pos += ROUNDUP(LE16(ent->rec_len), 4);
}
file_blocknum++;
/* sanity check the directory. 4MB should be enough */
if (file_blocknum > 1024) {
free(buf);
return -1;
}
}
}
/* note, trashes path */
static int ext2_walk(ext2_t *ext2, char *path, struct ext2_inode *start_inode, inodenum_t *inum, int recurse)
{
char *ptr;
struct ext2_inode inode;
struct ext2_inode dir_inode;
int err;
bool done;
LTRACEF("path '%s', start_inode %p, inum %p, recurse %d\n", path, start_inode, inum, recurse);
if (recurse > 4)
return ERR_RECURSE_TOO_DEEP;
/* chew up leading slashes */
ptr = &path[0];
while (*ptr == '/')
ptr++;
done = false;
memcpy(&dir_inode, start_inode, sizeof(struct ext2_inode));
while (!done) {
/* process the first component */
char *next_sep = strchr(ptr, '/');
if (next_sep) {
/* terminate the next component, giving us a substring */
*next_sep = 0;
} else {
/* this is the last component */
done = true;
}
LTRACEF("component '%s', done %d\n", ptr, done);
/* do the lookup on this component */
err = ext2_dir_lookup(ext2, &dir_inode, ptr, inum);
if (err < 0)
return err;
nextcomponent:
LTRACEF("inum %u\n", *inum);
/* load the next inode */
err = ext2_load_inode(ext2, *inum, &inode);
if (err < 0)
return err;
/* is it a symlink? */
if (S_ISLNK(inode.i_mode)) {
char link[512];
LTRACEF("hit symlink\n");
err = ext2_read_link(ext2, &inode, link, sizeof(link));
if (err < 0)
return err;
LTRACEF("symlink read returns %d '%s'\n", err, link);
/* recurse, parsing the link */
if (link[0] == '/') {
/* link starts with '/', so start over again at the rootfs */
err = ext2_walk(ext2, link, &ext2->root_inode, inum, recurse + 1);
} else {
err = ext2_walk(ext2, link, &dir_inode, inum, recurse + 1);
}
LTRACEF("recursive walk returns %d\n", err);
if (err < 0)
return err;
/* if we weren't done with our path parsing, start again with the result of this recurse */
if (!done) {
goto nextcomponent;
}
} else if (S_ISDIR(inode.i_mode)) {
/* for the next cycle, point the dir inode at our new directory */
memcpy(&dir_inode, &inode, sizeof(struct ext2_inode));
} else {
if (!done) {
/* we aren't done and this walked over a nondir, abort */
LTRACEF("not finished and component is nondir\n");
return ERR_NOT_FOUND;
}
}
if (!done) {
/* move to the next separator */
ptr = next_sep + 1;
/* consume multiple separators */
while (*ptr == '/')
ptr++;
}
}
return 0;
}
/* do a path parse, looking up each component */
int ext2_lookup(ext2_t *ext2, const char *_path, inodenum_t *inum)
{
LTRACEF("path '%s', inum %p\n", _path, inum);
char path[512];
strlcpy(path, _path, sizeof(path));
return ext2_walk(ext2, path, &ext2->root_inode, inum, 1);
}
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