lib/ext2fs/ext_attr.c

   1 /*
   2  * ext_attr.c --- extended attribute blocks
   3  *
   4  * Copyright (C) 2001 Andreas Gruenbacher, <a.gruenbacher@computer.org>
   5  *
   6  * Copyright (C) 2002 Theodore Ts'o.
   7  *
   8  * %Begin-Header%
   9  * This file may be redistributed under the terms of the GNU Public
  10  * License.
  11  * %End-Header%
  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 "ext2_ext_attr.h"
  23
  24 #include "ext2fs.h"
  25
  26 #ifdef EXT2FS_ENABLE_SWAPFS
  27 void ext2fs_swap_ext_attr(ext2_filsys fs, char *to, char *from)
  28 {
  29         struct ext2_ext_attr_header *from_header =
  30                 (struct ext2_ext_attr_header *)from;
  31         struct ext2_ext_attr_header *to_header =
  32                 (struct ext2_ext_attr_header *)to;
  33         struct ext2_ext_attr_entry *from_entry, *to_entry;
  34         char *from_end = (char *)from_header + fs->blocksize;
  35         int n;
  36
  37         if (to_header != from_header)
  38                 memcpy(to_header, from_header, fs->blocksize);
  39
  40         to_header->h_magic    = ext2fs_swab32(from_header->h_magic);
  41         to_header->h_blocks   = ext2fs_swab32(from_header->h_blocks);
  42         to_header->h_refcount = ext2fs_swab32(from_header->h_refcount);
  43         for (n=0; n<4; n++)
  44                 to_header->h_reserved[n] =
  45                         ext2fs_swab32(from_header->h_reserved[n]);
  46
  47         from_entry = (struct ext2_ext_attr_entry *)(from_header+1);
  48         to_entry   = (struct ext2_ext_attr_entry *)(to_header+1);
  49         while ((char *)from_entry < from_end && *(__u32 *)from_entry) {
  50                 to_entry->e_value_offs  =
  51                         ext2fs_swab16(from_entry->e_value_offs);
  52                 to_entry->e_value_block =
  53                         ext2fs_swab32(from_entry->e_value_block);
  54                 to_entry->e_value_size  =
  55                         ext2fs_swab32(from_entry->e_value_size);
  56                 from_entry = EXT2_EXT_ATTR_NEXT(from_entry);
  57                 to_entry   = EXT2_EXT_ATTR_NEXT(to_entry);
  58         }
  59 }
  60 #endif
  61
  62 errcode_t ext2fs_read_ext_attr(ext2_filsys fs, blk_t block, void *buf)
  63 {
  64         errcode_t       retval;
  65
  66         retval = io_channel_read_blk(fs->io, block, 1, buf);
  67         if (retval)
  68                 return retval;
  69 #ifdef EXT2FS_ENABLE_SWAPFS
  70         if ((fs->flags & (EXT2_FLAG_SWAP_BYTES|
  71                           EXT2_FLAG_SWAP_BYTES_READ)) != 0)
  72                 ext2fs_swap_ext_attr(fs, buf, buf);
  73 #endif
  74         return 0;
  75 }
  76
  77 errcode_t ext2fs_write_ext_attr(ext2_filsys fs, blk_t block, void *inbuf)
  78 {
  79         errcode_t       retval;
  80         char            *write_buf;
  81         char            *buf = NULL;
  82
  83 #ifdef EXT2FS_ENABLE_SWAPFS
  84         if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  85             (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)) {
  86                 retval = ext2fs_get_mem(fs->blocksize, (void **) &buf);
  87                 if (retval)
  88                         return retval;
  89                 write_buf = buf;
  90                 ext2fs_swap_ext_attr(fs, buf, inbuf);
  91         } else
  92 #endif
  93                 write_buf = (char *) inbuf;
  94         retval = io_channel_write_blk(fs->io, block, 1, write_buf);
  95         if (buf)
  96                 ext2fs_free_mem((void **) &buf);
  97         if (!retval)
  98                 ext2fs_mark_changed(fs);
  99         return retval;
 100 }
 101
 102 /*
 103  * This function adjusts the reference count of the EA block.
 104  */
 105 errcode_t ext2fs_adjust_ea_refcount(ext2_filsys fs, blk_t blk,
 106                                     char *block_buf, int adjust,
 107                                     __u32 *newcount)
 108 {
 109         errcode_t       retval;
 110         struct ext2_ext_attr_header *header;
 111         char    *buf = 0;
 112
 113         if ((blk >= fs->super->s_blocks_count) ||
 114             (blk < fs->super->s_first_data_block))
 115                 return EXT2_ET_BAD_EA_BLOCK_NUM;
 116
 117         if (!block_buf) {
 118                 retval = ext2fs_get_mem(fs->blocksize, (void **) &buf);
 119                 if (retval)
 120                         return retval;
 121                 block_buf = buf;
 122         }
 123
 124         retval = ext2fs_read_ext_attr(fs, blk, block_buf);
 125         if (retval)
 126                 goto errout;
 127
 128         header = (struct ext2_ext_attr_header *) block_buf;
 129         header->h_refcount += adjust;
 130         if (newcount)
 131                 *newcount = header->h_refcount;
 132
 133         retval = ext2fs_write_ext_attr(fs, blk, block_buf);
 134         if (retval)
 135                 goto errout;
 136
 137 errout:
 138         if (buf)
 139                 ext2fs_free_mem((void **) &buf);
 140         return retval;
 141 }