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

/*
 * link.c --- create links in a ext2fs directory
 *
 * Copyright (C) 1993, 1994 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

#include "ext2_fs.h"
#include "ext2fs.h"

struct link_struct  {
    const char  *name;
    int     namelen;
    ext2_ino_t  inode;
    int     flags;
    int     done;
    struct ext2_super_block *sb;
};

static int link_proc(struct ext2_dir_entry *dirent,
             int    offset,
             int    blocksize,
             char   *buf,
             void   *priv_data)
{
    struct link_struct *ls = (struct link_struct *) priv_data;
    struct ext2_dir_entry *next;
    int rec_len, min_rec_len;
    int ret = 0;

    rec_len = EXT2_DIR_REC_LEN(ls->namelen);

    /*
     * See if the following directory entry (if any) is unused;
     * if so, absorb it into this one.
     */
    next = (struct ext2_dir_entry *) (buf + offset + dirent->rec_len);
    if ((offset + dirent->rec_len < blocksize - 8) &&
        (next->inode == 0) &&
        (offset + dirent->rec_len + next->rec_len <= blocksize)) {
        dirent->rec_len += next->rec_len;
        ret = DIRENT_CHANGED;
    }

    /*
     * If the directory entry is used, see if we can split the
     * directory entry to make room for the new name.  If so,
     * truncate it and return.
     */
    if (dirent->inode) {
        min_rec_len = EXT2_DIR_REC_LEN(dirent->name_len & 0xFF);
        if (dirent->rec_len < (min_rec_len + rec_len))
            return ret;
        rec_len = dirent->rec_len - min_rec_len;
        dirent->rec_len = min_rec_len;
        next = (struct ext2_dir_entry *) (buf + offset +
                          dirent->rec_len);
        next->inode = 0;
        next->name_len = 0;
        next->rec_len = rec_len;
        return DIRENT_CHANGED;
    }

    /*
     * If we get this far, then the directory entry is not used.
     * See if we can fit the request entry in.  If so, do it.
     */
    if (dirent->rec_len < rec_len)
        return ret;
    dirent->inode = ls->inode;
    dirent->name_len = ls->namelen;
    strncpy(dirent->name, ls->name, ls->namelen);
    if (ls->sb->s_feature_incompat & EXT2_FEATURE_INCOMPAT_FILETYPE)
        dirent->name_len |= (ls->flags & 0x7) << 8;

    ls->done++;
    return DIRENT_ABORT|DIRENT_CHANGED;
}

/*
 * Note: the low 3 bits of the flags field are used as the directory
 * entry filetype.
 */
#ifdef __TURBOC__
# pragma argsused
#endif
errcode_t ext2fs_link(ext2_filsys fs, ext2_ino_t dir, const char *name,
              ext2_ino_t ino, int flags)
{
    errcode_t       retval;
    struct link_struct  ls;
    struct ext2_inode   inode;

    EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

    if (!(fs->flags & EXT2_FLAG_RW))
        return EXT2_ET_RO_FILSYS;

    ls.name = name;
    ls.namelen = name ? strlen(name) : 0;
    ls.inode = ino;
    ls.flags = flags;
    ls.done = 0;
    ls.sb = fs->super;

    retval = ext2fs_dir_iterate(fs, dir, DIRENT_FLAG_INCLUDE_EMPTY,
                    0, link_proc, &ls);
    if (retval)
        return retval;

    if (!ls.done)
        return EXT2_ET_DIR_NO_SPACE;

    if ((retval = ext2fs_read_inode(fs, dir, &inode)) != 0)
        return retval;

    if (inode.i_flags & EXT2_INDEX_FL) {
        inode.i_flags &= ~EXT2_INDEX_FL;
        if ((retval = ext2fs_write_inode(fs, dir, &inode)) != 0)
            return retval;
    }

    return 0;
}