source: MondoRescue/branches/stable/mindi-busybox/e2fsprogs/ext2fs/namei.c@ 821

/*
 * 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;
}