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 Library
   8  * General Public License, version 2.
   9  * %End-Header%
  10  */
  11
  12 #include "config.h"
  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 #define EXT4_MAX_REC_LEN                ((1<<16)-1)
  26
  27 errcode_t ext2fs_get_rec_len(ext2_filsys fs,
  28                              struct ext2_dir_entry *dirent,
  29                              unsigned int *rec_len)
  30 {
  31         unsigned int len = dirent->rec_len;
  32
  33         if (fs->blocksize < 65536)
  34                 *rec_len = len;
  35         else if (len == EXT4_MAX_REC_LEN || len == 0)
  36                 *rec_len = fs->blocksize;
  37         else
  38                 *rec_len = (len & 65532) | ((len & 3) << 16);
  39         return 0;
  40 }
  41
  42 errcode_t ext2fs_set_rec_len(ext2_filsys fs,
  43                              unsigned int len,
  44                              struct ext2_dir_entry *dirent)
  45 {
  46         if ((len > fs->blocksize) || (fs->blocksize > (1 << 18)) || (len & 3))
  47                 return EINVAL;
  48         if (len < 65536) {
  49                 dirent->rec_len = len;
  50                 return 0;
  51         }
  52         if (len == fs->blocksize) {
  53                 if (fs->blocksize == 65536)
  54                         dirent->rec_len = EXT4_MAX_REC_LEN;
  55                 else
  56                         dirent->rec_len = 0;
  57         } else
  58                 dirent->rec_len = (len & 65532) | ((len >> 16) & 3);
  59         return 0;
  60 }
  61
  62 /*
  63  * This function checks to see whether or not a potential deleted
  64  * directory entry looks valid.  What we do is check the deleted entry
  65  * and each successive entry to make sure that they all look valid and
  66  * that the last deleted entry ends at the beginning of the next
  67  * undeleted entry.  Returns 1 if the deleted entry looks valid, zero
  68  * if not valid.
  69  */
  70 static int ext2fs_validate_entry(ext2_filsys fs, char *buf,
  71                                  unsigned int offset,
  72                                  unsigned int final_offset)
  73 {
  74         struct ext2_dir_entry *dirent;
  75         unsigned int rec_len;
  76 #define DIRENT_MIN_LENGTH 12
  77
  78         while ((offset < final_offset) &&
  79                (offset <= fs->blocksize - DIRENT_MIN_LENGTH)) {
  80                 dirent = (struct ext2_dir_entry *)(buf + offset);
  81                 if (ext2fs_get_rec_len(fs, dirent, &rec_len))
  82                         return 0;
  83                 offset += rec_len;
  84                 if ((rec_len < 8) ||
  85                     ((rec_len % 4) != 0) ||
  86                     ((((unsigned) dirent->name_len & 0xFF)+8) > rec_len))
  87                         return 0;
  88         }
  89         return (offset == final_offset);
  90 }
  91
  92 errcode_t ext2fs_dir_iterate2(ext2_filsys fs,
  93                               ext2_ino_t dir,
  94                               int flags,
  95                               char *block_buf,
  96                               int (*func)(ext2_ino_t    dir,
  97                                           int           entry,
  98                                           struct ext2_dir_entry *dirent,
  99                                           int   offset,
 100                                           int   blocksize,
 101                                           char  *buf,
 102                                           void  *priv_data),
 103                               void *priv_data)
 104 {
 105         struct          dir_context     ctx;
 106         errcode_t       retval;
 107
 108         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 109
 110         retval = ext2fs_check_directory(fs, dir);
 111         if (retval)
 112                 return retval;
 113
 114         ctx.dir = dir;
 115         ctx.flags = flags;
 116         if (block_buf)
 117                 ctx.buf = block_buf;
 118         else {
 119                 retval = ext2fs_get_mem(fs->blocksize, &ctx.buf);
 120                 if (retval)
 121                         return retval;
 122         }
 123         ctx.func = func;
 124         ctx.priv_data = priv_data;
 125         ctx.errcode = 0;
 126         retval = ext2fs_block_iterate3(fs, dir, BLOCK_FLAG_READ_ONLY, 0,
 127                                        ext2fs_process_dir_block, &ctx);
 128         if (!block_buf)
 129                 ext2fs_free_mem(&ctx.buf);
 130         if (retval)
 131                 return retval;
 132         return ctx.errcode;
 133 }
 134
 135 struct xlate {
 136         int (*func)(struct ext2_dir_entry *dirent,
 137                     int         offset,
 138                     int         blocksize,
 139                     char        *buf,
 140                     void        *priv_data);
 141         void *real_private;
 142 };
 143
 144 static int xlate_func(ext2_ino_t dir EXT2FS_ATTR((unused)),
 145                       int entry EXT2FS_ATTR((unused)),
 146                       struct ext2_dir_entry *dirent, int offset,
 147                       int blocksize, char *buf, void *priv_data)
 148 {
 149         struct xlate *xl = (struct xlate *) priv_data;
 150
 151         return (*xl->func)(dirent, offset, blocksize, buf, xl->real_private);
 152 }
 153
 154 extern errcode_t ext2fs_dir_iterate(ext2_filsys fs,
 155                               ext2_ino_t dir,
 156                               int flags,
 157                               char *block_buf,
 158                               int (*func)(struct ext2_dir_entry *dirent,
 159                                           int   offset,
 160                                           int   blocksize,
 161                                           char  *buf,
 162                                           void  *priv_data),
 163                               void *priv_data)
 164 {
 165         struct xlate xl;
 166
 167         xl.real_private = priv_data;
 168         xl.func = func;
 169
 170         return ext2fs_dir_iterate2(fs, dir, flags, block_buf,
 171                                    xlate_func, &xl);
 172 }
 173
 174
 175 /*
 176  * Helper function which is private to this module.  Used by
 177  * ext2fs_dir_iterate() and ext2fs_dblist_dir_iterate()
 178  */
 179 int ext2fs_process_dir_block(ext2_filsys fs,
 180                              blk64_t    *blocknr,
 181                              e2_blkcnt_t blockcnt,
 182                              blk64_t    ref_block EXT2FS_ATTR((unused)),
 183                              int        ref_offset EXT2FS_ATTR((unused)),
 184                              void       *priv_data)
 185 {
 186         struct dir_context *ctx = (struct dir_context *) priv_data;
 187         unsigned int    offset = 0;
 188         unsigned int    next_real_entry = 0;
 189         int             ret = 0;
 190         int             changed = 0;
 191         int             do_abort = 0;
 192         unsigned int    rec_len, size;
 193         int             entry;
 194         struct ext2_dir_entry *dirent;
 195         int             csum_size = 0;
 196
 197         if (blockcnt < 0)
 198                 return 0;
 199
 200         entry = blockcnt ? DIRENT_OTHER_FILE : DIRENT_DOT_FILE;
 201
 202         ctx->errcode = ext2fs_read_dir_block4(fs, *blocknr, ctx->buf, 0,
 203                                               ctx->dir);
 204         if (ctx->errcode)
 205                 return BLOCK_ABORT;
 206
 207         if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 208                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
 209                 csum_size = sizeof(struct ext2_dir_entry_tail);
 210
 211         while (offset < (fs->blocksize - csum_size)) {
 212                 dirent = (struct ext2_dir_entry *) (ctx->buf + offset);
 213                 if (ext2fs_get_rec_len(fs, dirent, &rec_len))
 214                         return BLOCK_ABORT;
 215                 if (((offset + rec_len) > fs->blocksize) ||
 216                     (rec_len < 8) ||
 217                     ((rec_len % 4) != 0) ||
 218                     ((((unsigned) dirent->name_len & 0xFF)+8) > rec_len)) {
 219                         ctx->errcode = EXT2_ET_DIR_CORRUPTED;
 220                         return BLOCK_ABORT;
 221                 }
 222                 if (!dirent->inode &&
 223                     !(ctx->flags & DIRENT_FLAG_INCLUDE_EMPTY))
 224                         goto next;
 225
 226                 ret = (ctx->func)(ctx->dir,
 227                                   (next_real_entry > offset) ?
 228                                   DIRENT_DELETED_FILE : entry,
 229                                   dirent, offset,
 230                                   fs->blocksize, ctx->buf,
 231                                   ctx->priv_data);
 232                 if (entry < DIRENT_OTHER_FILE)
 233                         entry++;
 234
 235                 if (ret & DIRENT_CHANGED) {
 236                         if (ext2fs_get_rec_len(fs, dirent, &rec_len))
 237                                 return BLOCK_ABORT;
 238                         changed++;
 239                 }
 240                 if (ret & DIRENT_ABORT) {
 241                         do_abort++;
 242                         break;
 243                 }
 244 next:
 245                 if (next_real_entry == offset)
 246                         next_real_entry += rec_len;
 247
 248                 if (ctx->flags & DIRENT_FLAG_INCLUDE_REMOVED) {
 249                         size = ((dirent->name_len & 0xFF) + 11) & ~3;
 250
 251                         if (rec_len != size)  {
 252                                 unsigned int final_offset;
 253
 254                                 final_offset = offset + rec_len;
 255                                 offset += size;
 256                                 while (offset < final_offset &&
 257                                        !ext2fs_validate_entry(fs, ctx->buf,
 258                                                               offset,
 259                                                               final_offset))
 260                                         offset += 4;
 261                                 continue;
 262                         }
 263                 }
 264                 offset += rec_len;
 265         }
 266
 267         if (changed) {
 268                 ctx->errcode = ext2fs_write_dir_block4(fs, *blocknr, ctx->buf,
 269                                                        0, ctx->dir);
 270                 if (ctx->errcode)
 271                         return BLOCK_ABORT;
 272         }
 273         if (do_abort)
 274                 return BLOCK_ABORT;
 275         return 0;
 276 }
 277