lib/ext2fs/rw_bitmaps.c

   1 /*
   2  * rw_bitmaps.c --- routines to read and write the  inode and block bitmaps.
   3  *
   4  * Copyright (C) 1993, 1994, 1994, 1996 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 #include <stdio.h>
  13 #include <string.h>
  14 #if HAVE_UNISTD_H
  15 #include <unistd.h>
  16 #endif
  17 #include <stdlib.h>
  18 #include <fcntl.h>
  19 #include <time.h>
  20 #ifdef HAVE_SYS_STAT_H
  21 #include <sys/stat.h>
  22 #endif
  23 #ifdef HAVE_SYS_TYPES_H
  24 #include <sys/types.h>
  25 #endif
  26 #if HAVE_ERRNO_H
  27 #include <errno.h>
  28 #endif
  29
  30 #include <linux/ext2_fs.h>
  31
  32 #include "ext2fs.h"
  33
  34 #ifdef __powerpc__
  35 /*
  36  * On the PowerPC, the big-endian variant of the ext2 filesystem
  37  * has its bitmaps stored as 32-bit words with bit 0 as the LSB
  38  * of each word.  Thus a bitmap with only bit 0 set would be, as
  39  * a string of bytes, 00 00 00 01 00 ...
  40  * To cope with this, we byte-reverse each word of a bitmap if
  41  * we have a big-endian filesystem, that is, if we are *not*
  42  * byte-swapping other word-sized numbers.
  43  */
  44 #define EXT2_BIG_ENDIAN_BITMAPS
  45 #endif
  46
  47 #ifdef EXT2_BIG_ENDIAN_BITMAPS
  48 void ext2fs_swap_bitmap(ext2_filsys fs, char *bitmap, int nbytes)
  49 {
  50         __u32 *p = (__u32 *) bitmap;
  51         int n;
  52
  53         for (n = nbytes / sizeof(__u32); n > 0; --n, ++p)
  54                 *p = ext2fs_swab32(*p);
  55 }
  56 #endif
  57
  58 errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs)
  59 {
  60         int             i;
  61         size_t          nbytes;
  62         errcode_t       retval;
  63         char * inode_bitmap = fs->inode_map->bitmap;
  64         char * bitmap_block = NULL;
  65         blk_t           blk;
  66
  67         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  68
  69         if (!(fs->flags & EXT2_FLAG_RW))
  70                 return EXT2_ET_RO_FILSYS;
  71         if (!inode_bitmap)
  72                 return 0;
  73         nbytes = (size_t) ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
  74
  75         bitmap_block = malloc(fs->blocksize);
  76         if (!bitmap_block)
  77                 return ENOMEM;
  78         memset(bitmap_block, 0xff, fs->blocksize);
  79         for (i = 0; i < fs->group_desc_count; i++) {
  80                 memcpy(bitmap_block, inode_bitmap, nbytes);
  81                 blk = fs->group_desc[i].bg_inode_bitmap;
  82                 if (blk) {
  83 #ifdef EXT2_BIG_ENDIAN_BITMAPS
  84                         if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  85                               (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
  86                                 ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
  87 #endif
  88                         retval = io_channel_write_blk(fs->io, blk, 1,
  89                                                       bitmap_block);
  90                         if (retval)
  91                                 return EXT2_ET_INODE_BITMAP_WRITE;
  92                 }
  93                 inode_bitmap += nbytes;
  94         }
  95         fs->flags |= EXT2_FLAG_CHANGED;
  96         fs->flags &= ~EXT2_FLAG_IB_DIRTY;
  97         free(bitmap_block);
  98         return 0;
  99 }
 100
 101 errcode_t ext2fs_write_block_bitmap (ext2_filsys fs)
 102 {
 103         int             i;
 104         int             j;
 105         int             nbytes;
 106         int             nbits;
 107         errcode_t       retval;
 108         char * block_bitmap = fs->block_map->bitmap;
 109         char * bitmap_block = NULL;
 110         blk_t           blk;
 111
 112         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 113
 114         if (!(fs->flags & EXT2_FLAG_RW))
 115                 return EXT2_ET_RO_FILSYS;
 116         if (!block_bitmap)
 117                 return 0;
 118         nbytes = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
 119         bitmap_block = malloc(fs->blocksize);
 120         if (!bitmap_block)
 121                 return ENOMEM;
 122         memset(bitmap_block, 0xff, fs->blocksize);
 123         for (i = 0; i < fs->group_desc_count; i++) {
 124                 memcpy(bitmap_block, block_bitmap, nbytes);
 125                 if (i == fs->group_desc_count - 1) {
 126                         /* Force bitmap padding for the last group */
 127                         nbits = (int) ((fs->super->s_blocks_count
 128                                         - fs->super->s_first_data_block)
 129                                        % EXT2_BLOCKS_PER_GROUP(fs->super));
 130                         if (nbits)
 131                                 for (j = nbits; j < fs->blocksize * 8; j++)
 132                                         ext2fs_set_bit(j, bitmap_block);
 133                 }
 134                 blk = fs->group_desc[i].bg_block_bitmap;
 135                 if (blk) {
 136 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 137                         if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 138                               (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
 139                                 ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
 140 #endif
 141                         retval = io_channel_write_blk(fs->io, blk, 1,
 142                                                       bitmap_block);
 143                         if (retval)
 144                                 return EXT2_ET_BLOCK_BITMAP_WRITE;
 145                 }
 146                 block_bitmap += nbytes;
 147         }
 148         fs->flags |= EXT2_FLAG_CHANGED;
 149         fs->flags &= ~EXT2_FLAG_BB_DIRTY;
 150         free(bitmap_block);
 151         return 0;
 152 }
 153
 154 static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
 155 {
 156         int i;
 157         char *block_bitmap = 0, *inode_bitmap = 0;
 158         char *buf;
 159         errcode_t retval;
 160         int block_nbytes = (int) EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
 161         int inode_nbytes = (int) EXT2_INODES_PER_GROUP(fs->super) / 8;
 162         blk_t   blk;
 163
 164         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 165
 166         fs->write_bitmaps = ext2fs_write_bitmaps;
 167
 168         buf = malloc(strlen(fs->device_name) + 80);
 169         if (do_block) {
 170                 if (fs->block_map)
 171                         ext2fs_free_block_bitmap(fs->block_map);
 172                 sprintf(buf, "block bitmap for %s", fs->device_name);
 173                 retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
 174                 if (retval)
 175                         goto cleanup;
 176                 block_bitmap = fs->block_map->bitmap;
 177         }
 178         if (do_inode) {
 179                 if (fs->inode_map)
 180                         ext2fs_free_inode_bitmap(fs->inode_map);
 181                 sprintf(buf, "inode bitmap for %s", fs->device_name);
 182                 retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
 183                 if (retval)
 184                         goto cleanup;
 185                 inode_bitmap = fs->inode_map->bitmap;
 186         }
 187         free(buf);
 188
 189         for (i = 0; i < fs->group_desc_count; i++) {
 190                 if (block_bitmap) {
 191                         blk = fs->group_desc[i].bg_block_bitmap;
 192                         if (blk) {
 193                                 retval = io_channel_read_blk(fs->io, blk,
 194                                              -block_nbytes, block_bitmap);
 195                                 if (retval) {
 196                                         retval = EXT2_ET_BLOCK_BITMAP_READ;
 197                                         goto cleanup;
 198                                 }
 199 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 200                                 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 201                                       (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
 202                                         ext2fs_swap_bitmap(fs, block_bitmap, block_nbytes);
 203 #endif
 204                         } else
 205                                 memset(block_bitmap, 0, block_nbytes);
 206                         block_bitmap += block_nbytes;
 207                 }
 208                 if (inode_bitmap) {
 209                         blk = fs->group_desc[i].bg_inode_bitmap;
 210                         if (blk) {
 211                                 retval = io_channel_read_blk(fs->io, blk,
 212                                              -inode_nbytes, inode_bitmap);
 213                                 if (retval) {
 214                                         retval = EXT2_ET_INODE_BITMAP_READ;
 215                                         goto cleanup;
 216                                 }
 217 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 218                                 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 219                                       (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
 220                                         ext2fs_swap_bitmap(fs, inode_bitmap, inode_nbytes);
 221 #endif
 222                         } else
 223                                 memset(inode_bitmap, 0, inode_nbytes);
 224                         inode_bitmap += inode_nbytes;
 225                 }
 226         }
 227         return 0;
 228
 229 cleanup:
 230         if (do_block) {
 231                 free(fs->block_map);
 232                 fs->block_map = 0;
 233         }
 234         if (do_inode) {
 235                 free(fs->inode_map);
 236                 fs->inode_map = 0;
 237         }
 238         if (buf)
 239                 free(buf);
 240         return retval;
 241 }
 242
 243 errcode_t ext2fs_read_inode_bitmap (ext2_filsys fs)
 244 {
 245         return read_bitmaps(fs, 1, 0);
 246 }
 247
 248 errcode_t ext2fs_read_block_bitmap(ext2_filsys fs)
 249 {
 250         return read_bitmaps(fs, 0, 1);
 251 }
 252
 253 errcode_t ext2fs_read_bitmaps(ext2_filsys fs)
 254 {
 255
 256         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 257
 258         return read_bitmaps(fs, !fs->inode_map, !fs->block_map);
 259 }
 260
 261 errcode_t ext2fs_write_bitmaps(ext2_filsys fs)
 262 {
 263         errcode_t       retval;
 264
 265         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 266
 267         if (fs->block_map && ext2fs_test_bb_dirty(fs)) {
 268                 retval = ext2fs_write_block_bitmap(fs);
 269                 if (retval)
 270                         return retval;
 271         }
 272         if (fs->inode_map && ext2fs_test_ib_dirty(fs)) {
 273                 retval = ext2fs_write_inode_bitmap(fs);
 274                 if (retval)
 275                         return retval;
 276         }
 277         return 0;
 278 }
 279