release/src/router/busybox/e2fsprogs/old_e2fsprogs/ext2fs/link.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * link.c --- create links in a ext2fs directory
   4  *
   5  * Copyright (C) 1993, 1994 Theodore Ts'o.
   6  *
   7  * %Begin-Header%
   8  * This file may be redistributed under the terms of the GNU Public
   9  * License.
  10  * %End-Header%
  11  */
  12
  13 #include <stdio.h>
  14 #include <string.h>
  15 #if HAVE_UNISTD_H
  16 #include <unistd.h>
  17 #endif
  18
  19 #include "ext2_fs.h"
  20 #include "ext2fs.h"
  21
  22 struct link_struct  {
  23         const char      *name;
  24         int             namelen;
  25         ext2_ino_t      inode;
  26         int             flags;
  27         int             done;
  28         struct ext2_super_block *sb;
  29 };
  30
  31 static int link_proc(struct ext2_dir_entry *dirent,
  32                      int        offset,
  33                      int        blocksize,
  34                      char       *buf,
  35                      void       *priv_data)
  36 {
  37         struct link_struct *ls = (struct link_struct *) priv_data;
  38         struct ext2_dir_entry *next;
  39         int rec_len, min_rec_len;
  40         int ret = 0;
  41
  42         rec_len = EXT2_DIR_REC_LEN(ls->namelen);
  43
  44         /*
  45          * See if the following directory entry (if any) is unused;
  46          * if so, absorb it into this one.
  47          */
  48         next = (struct ext2_dir_entry *) (buf + offset + dirent->rec_len);
  49         if ((offset + dirent->rec_len < blocksize - 8) &&
  50             (next->inode == 0) &&
  51             (offset + dirent->rec_len + next->rec_len <= blocksize)) {
  52                 dirent->rec_len += next->rec_len;
  53                 ret = DIRENT_CHANGED;
  54         }
  55
  56         /*
  57          * If the directory entry is used, see if we can split the
  58          * directory entry to make room for the new name.  If so,
  59          * truncate it and return.
  60          */
  61         if (dirent->inode) {
  62                 min_rec_len = EXT2_DIR_REC_LEN(dirent->name_len & 0xFF);
  63                 if (dirent->rec_len < (min_rec_len + rec_len))
  64                         return ret;
  65                 rec_len = dirent->rec_len - min_rec_len;
  66                 dirent->rec_len = min_rec_len;
  67                 next = (struct ext2_dir_entry *) (buf + offset +
  68                                                   dirent->rec_len);
  69                 next->inode = 0;
  70                 next->name_len = 0;
  71                 next->rec_len = rec_len;
  72                 return DIRENT_CHANGED;
  73         }
  74
  75         /*
  76          * If we get this far, then the directory entry is not used.
  77          * See if we can fit the request entry in.  If so, do it.
  78          */
  79         if (dirent->rec_len < rec_len)
  80                 return ret;
  81         dirent->inode = ls->inode;
  82         dirent->name_len = ls->namelen;
  83         strncpy(dirent->name, ls->name, ls->namelen);
  84         if (ls->sb->s_feature_incompat & EXT2_FEATURE_INCOMPAT_FILETYPE)
  85                 dirent->name_len |= (ls->flags & 0x7) << 8;
  86
  87         ls->done++;
  88         return DIRENT_ABORT|DIRENT_CHANGED;
  89 }
  90
  91 /*
  92  * Note: the low 3 bits of the flags field are used as the directory
  93  * entry filetype.
  94  */
  95 #ifdef __TURBOC__
  96 # pragma argsused
  97 #endif
  98 errcode_t ext2fs_link(ext2_filsys fs, ext2_ino_t dir, const char *name,
  99                       ext2_ino_t ino, int flags)
 100 {
 101         errcode_t               retval;
 102         struct link_struct      ls;
 103         struct ext2_inode       inode;
 104
 105         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 106
 107         if (!(fs->flags & EXT2_FLAG_RW))
 108                 return EXT2_ET_RO_FILSYS;
 109
 110         ls.name = name;
 111         ls.namelen = name ? strlen(name) : 0;
 112         ls.inode = ino;
 113         ls.flags = flags;
 114         ls.done = 0;
 115         ls.sb = fs->super;
 116
 117         retval = ext2fs_dir_iterate(fs, dir, DIRENT_FLAG_INCLUDE_EMPTY,
 118                                     0, link_proc, &ls);
 119         if (retval)
 120                 return retval;
 121
 122         if (!ls.done)
 123                 return EXT2_ET_DIR_NO_SPACE;
 124
 125         if ((retval = ext2fs_read_inode(fs, dir, &inode)) != 0)
 126                 return retval;
 127
 128         if (inode.i_flags & EXT2_INDEX_FL) {
 129                 inode.i_flags &= ~EXT2_INDEX_FL;
 130                 if ((retval = ext2fs_write_inode(fs, dir, &inode)) != 0)
 131                         return retval;
 132         }
 133
 134         return 0;
 135 }