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/* vi: set sw=4 ts=4: */
/*
* namei.c --- ext2fs directory lookup operations
*
* Copyright (C) 1993, 1994, 1994, 1995 Theodore Ts'o.
*
* %Begin-Header%
* This file may be redistributed under the terms of the GNU Public
* License.
* %End-Header%
*/
#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
/* #define NAMEI_DEBUG */
#include "ext2_fs.h"
#include "ext2fs.h"
static errcode_t open_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t base,
const char *pathname, size_t pathlen, int follow,
int link_count, char *buf, ext2_ino_t *res_inode);
static errcode_t follow_link(ext2_filsys fs, ext2_ino_t root, ext2_ino_t dir,
ext2_ino_t inode, int link_count,
char *buf, ext2_ino_t *res_inode)
{
char *pathname;
char *buffer = 0;
errcode_t retval;
struct ext2_inode ei;
#ifdef NAMEI_DEBUG
printf("follow_link: root=%lu, dir=%lu, inode=%lu, lc=%d\n",
root, dir, inode, link_count);
#endif
retval = ext2fs_read_inode (fs, inode, &ei);
if (retval) return retval;
if (!LINUX_S_ISLNK (ei.i_mode)) {
*res_inode = inode;
return 0;
}
if (link_count++ > 5) {
return EXT2_ET_SYMLINK_LOOP;
}
if (ext2fs_inode_data_blocks(fs, &ei)) {
retval = ext2fs_get_mem(fs->blocksize, &buffer);
if (retval)
return retval;
retval = io_channel_read_blk(fs->io, ei.i_block[0], 1, buffer);
if (retval) {
ext2fs_free_mem(&buffer);
return retval;
}
pathname = buffer;
} else
pathname = (char *)&(ei.i_block[0]);
retval = open_namei(fs, root, dir, pathname, ei.i_size, 1,
link_count, buf, res_inode);
ext2fs_free_mem(&buffer);
return retval;
}
/*
* This routine interprets a pathname in the context of the current
* directory and the root directory, and returns the inode of the
* containing directory, and a pointer to the filename of the file
* (pointing into the pathname) and the length of the filename.
*/
static errcode_t dir_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t dir,
const char *pathname, int pathlen,
int link_count, char *buf,
const char **name, int *namelen,
ext2_ino_t *res_inode)
{
char c;
const char *thisname;
int len;
ext2_ino_t inode;
errcode_t retval;
if ((c = *pathname) == '/') {
dir = root;
pathname++;
pathlen--;
}
while (1) {
thisname = pathname;
for (len=0; --pathlen >= 0;len++) {
c = *(pathname++);
if (c == '/')
break;
}
if (pathlen < 0)
break;
retval = ext2fs_lookup (fs, dir, thisname, len, buf, &inode);
if (retval) return retval;
retval = follow_link (fs, root, dir, inode,
link_count, buf, &dir);
if (retval) return retval;
}
*name = thisname;
*namelen = len;
*res_inode = dir;
return 0;
}
static errcode_t open_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t base,
const char *pathname, size_t pathlen, int follow,
int link_count, char *buf, ext2_ino_t *res_inode)
{
const char *basename;
int namelen;
ext2_ino_t dir, inode;
errcode_t retval;
#ifdef NAMEI_DEBUG
printf("open_namei: root=%lu, dir=%lu, path=%*s, lc=%d\n",
root, base, pathlen, pathname, link_count);
#endif
retval = dir_namei(fs, root, base, pathname, pathlen,
link_count, buf, &basename, &namelen, &dir);
if (retval) return retval;
if (!namelen) { /* special case: '/usr/' etc */
*res_inode=dir;
return 0;
}
retval = ext2fs_lookup (fs, dir, basename, namelen, buf, &inode);
if (retval)
return retval;
if (follow) {
retval = follow_link(fs, root, dir, inode, link_count,
buf, &inode);
if (retval)
return retval;
}
#ifdef NAMEI_DEBUG
printf("open_namei: (link_count=%d) returns %lu\n",
link_count, inode);
#endif
*res_inode = inode;
return 0;
}
errcode_t ext2fs_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
const char *name, ext2_ino_t *inode)
{
char *buf;
errcode_t retval;
EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
retval = ext2fs_get_mem(fs->blocksize, &buf);
if (retval)
return retval;
retval = open_namei(fs, root, cwd, name, strlen(name), 0, 0,
buf, inode);
ext2fs_free_mem(&buf);
return retval;
}
errcode_t ext2fs_namei_follow(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
const char *name, ext2_ino_t *inode)
{
char *buf;
errcode_t retval;
EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
retval = ext2fs_get_mem(fs->blocksize, &buf);
if (retval)
return retval;
retval = open_namei(fs, root, cwd, name, strlen(name), 1, 0,
buf, inode);
ext2fs_free_mem(&buf);
return retval;
}
errcode_t ext2fs_follow_link(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
ext2_ino_t inode, ext2_ino_t *res_inode)
{
char *buf;
errcode_t retval;
EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
retval = ext2fs_get_mem(fs->blocksize, &buf);
if (retval)
return retval;
retval = follow_link(fs, root, cwd, inode, 0, buf, res_inode);
ext2fs_free_mem(&buf);
return retval;
}
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