release/src/router/busybox/e2fsprogs/ext2fs/dir_iterate.c

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