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

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * valid_blk.c --- does the inode have valid blocks?
   4  *
   5  * Copyright 1997 by 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
  14 #include <stdio.h>
  15 #if HAVE_UNISTD_H
  16 #include <unistd.h>
  17 #endif
  18 #include <string.h>
  19 #include <time.h>
  20
  21 #include "ext2_fs.h"
  22 #include "ext2fs.h"
  23
  24 /*
  25  * This function returns 1 if the inode's block entries actually
  26  * contain block entries.
  27  */
  28 int ext2fs_inode_has_valid_blocks(struct ext2_inode *inode)
  29 {
  30         /*
  31          * Only directories, regular files, and some symbolic links
  32          * have valid block entries.
  33          */
  34         if (!LINUX_S_ISDIR(inode->i_mode) && !LINUX_S_ISREG(inode->i_mode) &&
  35             !LINUX_S_ISLNK(inode->i_mode))
  36                 return 0;
  37
  38         /*
  39          * If the symbolic link is a "fast symlink", then the symlink
  40          * target is stored in the block entries.
  41          */
  42         if (LINUX_S_ISLNK (inode->i_mode)) {
  43                 if (inode->i_file_acl == 0) {
  44                         /* With no EA block, we can rely on i_blocks */
  45                         if (inode->i_blocks == 0)
  46                                 return 0;
  47                 } else {
  48                         /* With an EA block, life gets more tricky */
  49                         if (inode->i_size >= EXT2_N_BLOCKS*4)
  50                                 return 1; /* definitely using i_block[] */
  51                         if (inode->i_size > 4 && inode->i_block[1] == 0)
  52                                 return 1; /* definitely using i_block[] */
  53                         return 0; /* Probably a fast symlink */
  54                 }
  55         }
  56         return 1;
  57 }