lib/ext2fs/valid_blk.c

   1 /*
   2  * valid_blk.c --- does the inode have valid blocks?
   3  *
   4  * Copyright 1997 by 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
  13 #include <stdio.h>
  14 #if HAVE_UNISTD_H
  15 #include <unistd.h>
  16 #endif
  17 #include <string.h>
  18 #include <time.h>
  19
  20 #include "ext2_fs.h"
  21 #include "ext2fs.h"
  22
  23 /*
  24  * This function returns 1 if the inode's block entries actually
  25  * contain block entries.
  26  */
  27 int ext2fs_inode_has_valid_blocks(struct ext2_inode *inode)
  28 {
  29         /*
  30          * Only directories, regular files, and some symbolic links
  31          * have valid block entries.
  32          */
  33         if (!LINUX_S_ISDIR(inode->i_mode) && !LINUX_S_ISREG(inode->i_mode) &&
  34             !LINUX_S_ISLNK(inode->i_mode))
  35                 return 0;
  36
  37         /*
  38          * If the symbolic link is a "fast symlink", then the symlink
  39          * target is stored in the block entries.
  40          */
  41         if (LINUX_S_ISLNK (inode->i_mode)) {
  42                 if (inode->i_file_acl == 0) {
  43                         /* With no EA block, we can rely on i_blocks */
  44                         if (inode->i_blocks == 0)
  45                                 return 0;
  46                 } else {
  47                         /* With an EA block, life gets more tricky */
  48                         if (inode->i_size >= EXT2_N_BLOCKS*4)
  49                                 return 1; /* definitely using i_block[] */
  50                         if (inode->i_size > 4 && inode->i_block[1] == 0)
  51                                 return 1; /* definitely using i_block[] */
  52                         return 0; /* Probably a fast symlink */
  53                 }
  54         }
  55         return 1;
  56 }