lib/ext2fs/dir_iterate.c

   1 /*
   2  * dir_iterate.c --- ext2fs directory iteration operations
   3  *
   4  * Copyright (C) 1993, 1994, 1994, 1995, 1996, 1997 Theodore Ts'o.
   5  *
   6  * %Begin-Header%
   7  * This file may be redistributed under the terms of the GNU Public
   8  * License.
   9  * %End-Header%
  10  */
  11
  12 #include <stdio.h>
  13 #include <string.h>
  14 #if HAVE_UNISTD_H
  15 #include <unistd.h>
  16 #endif
  17 #if HAVE_ERRNO_H
  18 #include <errno.h>
  19 #endif
  20
  21 #include "ext2_fs.h"
  22 #include "ext2fsP.h"
  23
  24 /*
  25  * This function checks to see whether or not a potential deleted
  26  * directory entry looks valid.  What we do is check the deleted entry
  27  * and each successive entry to make sure that they all look valid and
  28  * that the last deleted entry ends at the beginning of the next
  29  * undeleted entry.  Returns 1 if the deleted entry looks valid, zero
  30  * if not valid.
  31  */
  32 static int ext2fs_validate_entry(char *buf, int offset, int final_offset)
  33 {
  34         struct ext2_dir_entry *dirent;
  35
  36         while (offset < final_offset) {
  37                 dirent = (struct ext2_dir_entry *)(buf + offset);
  38                 offset += dirent->rec_len;
  39                 if ((dirent->rec_len < 8) ||
  40                     ((dirent->rec_len % 4) != 0) ||
  41                     (((dirent->name_len & 0xFF)+8) > dirent->rec_len))
  42                         return 0;
  43         }
  44         return (offset == final_offset);
  45 }
  46
  47 errcode_t ext2fs_dir_iterate2(ext2_filsys fs,
  48                               ext2_ino_t dir,
  49                               int flags,
  50                               char *block_buf,
  51                               int (*func)(ext2_ino_t    dir,
  52                                           int           entry,
  53                                           struct ext2_dir_entry *dirent,
  54                                           int   offset,
  55                                           int   blocksize,
  56                                           char  *buf,
  57                                           void  *priv_data),
  58                               void *priv_data)
  59 {
  60         struct          dir_context     ctx;
  61         errcode_t       retval;
  62
  63         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  64
  65         retval = ext2fs_check_directory(fs, dir);
  66         if (retval)
  67                 return retval;
  68
  69         ctx.dir = dir;
  70         ctx.flags = flags;
  71         if (block_buf)
  72                 ctx.buf = block_buf;
  73         else {
  74                 retval = ext2fs_get_mem(fs->blocksize, &ctx.buf);
  75                 if (retval)
  76                         return retval;
  77         }
  78         ctx.func = func;
  79         ctx.priv_data = priv_data;
  80         ctx.errcode = 0;
  81         retval = ext2fs_block_iterate2(fs, dir, BLOCK_FLAG_READ_ONLY, 0,
  82                                        ext2fs_process_dir_block, &ctx);
  83         if (!block_buf)
  84                 ext2fs_free_mem(&ctx.buf);
  85         if (retval)
  86                 return retval;
  87         return ctx.errcode;
  88 }
  89
  90 struct xlate {
  91         int (*func)(struct ext2_dir_entry *dirent,
  92                     int         offset,
  93                     int         blocksize,
  94                     char        *buf,
  95                     void        *priv_data);
  96         void *real_private;
  97 };
  98
  99 static int xlate_func(ext2_ino_t dir EXT2FS_ATTR((unused)),
 100                       int entry EXT2FS_ATTR((unused)),
 101                       struct ext2_dir_entry *dirent, int offset,
 102                       int blocksize, char *buf, void *priv_data)
 103 {
 104         struct xlate *xl = (struct xlate *) priv_data;
 105
 106         return (*xl->func)(dirent, offset, blocksize, buf, xl->real_private);
 107 }
 108
 109 extern errcode_t ext2fs_dir_iterate(ext2_filsys fs,
 110                               ext2_ino_t dir,
 111                               int flags,
 112                               char *block_buf,
 113                               int (*func)(struct ext2_dir_entry *dirent,
 114                                           int   offset,
 115                                           int   blocksize,
 116                                           char  *buf,
 117                                           void  *priv_data),
 118                               void *priv_data)
 119 {
 120         struct xlate xl;
 121
 122         xl.real_private = priv_data;
 123         xl.func = func;
 124
 125         return ext2fs_dir_iterate2(fs, dir, flags, block_buf,
 126                                    xlate_func, &xl);
 127 }
 128
 129
 130 /*
 131  * Helper function which is private to this module.  Used by
 132  * ext2fs_dir_iterate() and ext2fs_dblist_dir_iterate()
 133  */
 134 int ext2fs_process_dir_block(ext2_filsys fs,
 135                              blk_t      *blocknr,
 136                              e2_blkcnt_t blockcnt,
 137                              blk_t      ref_block EXT2FS_ATTR((unused)),
 138                              int        ref_offset EXT2FS_ATTR((unused)),
 139                              void       *priv_data)
 140 {
 141         struct dir_context *ctx = (struct dir_context *) priv_data;
 142         unsigned int    offset = 0;
 143         unsigned int    next_real_entry = 0;
 144         int             ret = 0;
 145         int             changed = 0;
 146         int             do_abort = 0;
 147         int             entry, size;
 148         struct ext2_dir_entry *dirent;
 149
 150         if (blockcnt < 0)
 151                 return 0;
 152
 153         entry = blockcnt ? DIRENT_OTHER_FILE : DIRENT_DOT_FILE;
 154
 155         ctx->errcode = ext2fs_read_dir_block(fs, *blocknr, ctx->buf);
 156         if (ctx->errcode)
 157                 return BLOCK_ABORT;
 158
 159         while (offset < fs->blocksize) {
 160                 dirent = (struct ext2_dir_entry *) (ctx->buf + offset);
 161                 if (((offset + dirent->rec_len) > fs->blocksize) ||
 162                     (dirent->rec_len < 8) ||
 163                     ((dirent->rec_len % 4) != 0) ||
 164                     (((dirent->name_len & 0xFF)+8) > dirent->rec_len)) {
 165                         ctx->errcode = EXT2_ET_DIR_CORRUPTED;
 166                         return BLOCK_ABORT;
 167                 }
 168                 if (!dirent->inode &&
 169                     !(ctx->flags & DIRENT_FLAG_INCLUDE_EMPTY))
 170                         goto next;
 171
 172                 ret = (ctx->func)(ctx->dir,
 173                                   (next_real_entry > offset) ?
 174                                   DIRENT_DELETED_FILE : entry,
 175                                   dirent, offset,
 176                                   fs->blocksize, ctx->buf,
 177                                   ctx->priv_data);
 178                 if (entry < DIRENT_OTHER_FILE)
 179                         entry++;
 180
 181                 if (ret & DIRENT_CHANGED)
 182                         changed++;
 183                 if (ret & DIRENT_ABORT) {
 184                         do_abort++;
 185                         break;
 186                 }
 187 next:
 188                 if (next_real_entry == offset)
 189                         next_real_entry += dirent->rec_len;
 190
 191                 if (ctx->flags & DIRENT_FLAG_INCLUDE_REMOVED) {
 192                         size = ((dirent->name_len & 0xFF) + 11) & ~3;
 193
 194                         if (dirent->rec_len != size)  {
 195                                 unsigned int final_offset;
 196
 197                                 final_offset = offset + dirent->rec_len;
 198                                 offset += size;
 199                                 while (offset < final_offset &&
 200                                        !ext2fs_validate_entry(ctx->buf,
 201                                                               offset,
 202                                                               final_offset))
 203                                         offset += 4;
 204                                 continue;
 205                         }
 206                 }
 207                 offset += dirent->rec_len;
 208         }
 209
 210         if (changed) {
 211                 ctx->errcode = ext2fs_write_dir_block(fs, *blocknr, ctx->buf);
 212                 if (ctx->errcode)
 213                         return BLOCK_ABORT;
 214         }
 215         if (do_abort)
 216                 return BLOCK_ABORT;
 217         return 0;
 218 }
 219