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 <fcntl.h>
  18 #include <time.h>
  19 #ifdef HAVE_SYS_STAT_H
  20 #include <sys/stat.h>
  21 #endif
  22 #ifdef HAVE_SYS_TYPES_H
  23 #include <sys/types.h>
  24 #endif
  25
  26 #include "ext2_fs.h"
  27 #include "ext2fs.h"
  28 #include "e2image.h"
  29
  30 #if defined(__powerpc__) && defined(EXT2FS_ENABLE_SWAPFS)
  31 /*
  32  * On the PowerPC, the big-endian variant of the ext2 filesystem
  33  * has its bitmaps stored as 32-bit words with bit 0 as the LSB
  34  * of each word.  Thus a bitmap with only bit 0 set would be, as
  35  * a string of bytes, 00 00 00 01 00 ...
  36  * To cope with this, we byte-reverse each word of a bitmap if
  37  * we have a big-endian filesystem, that is, if we are *not*
  38  * byte-swapping other word-sized numbers.
  39  */
  40 #define EXT2_BIG_ENDIAN_BITMAPS
  41 #endif
  42
  43 #ifdef EXT2_BIG_ENDIAN_BITMAPS
  44 void ext2fs_swap_bitmap(ext2_filsys fs, char *bitmap, int nbytes)
  45 {
  46         __u32 *p = (__u32 *) bitmap;
  47         int n;
  48
  49         for (n = nbytes / sizeof(__u32); n > 0; --n, ++p)
  50                 *p = ext2fs_swab32(*p);
  51 }
  52 #endif
  53
  54 errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs)
  55 {
  56         dgrp_t          i;
  57         size_t          nbytes;
  58         errcode_t       retval;
  59         char * inode_bitmap = fs->inode_map->bitmap;
  60         char * bitmap_block = NULL;
  61         blk_t           blk;
  62
  63         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  64
  65         if (!(fs->flags & EXT2_FLAG_RW))
  66                 return EXT2_ET_RO_FILSYS;
  67         if (!inode_bitmap)
  68                 return 0;
  69         nbytes = (size_t) ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
  70
  71         retval = ext2fs_get_mem(fs->blocksize, (void **) &bitmap_block);
  72         if (retval)
  73                 return retval;
  74         memset(bitmap_block, 0xff, fs->blocksize);
  75         for (i = 0; i < fs->group_desc_count; i++) {
  76                 memcpy(bitmap_block, inode_bitmap, nbytes);
  77                 blk = fs->group_desc[i].bg_inode_bitmap;
  78                 if (blk) {
  79 #ifdef EXT2_BIG_ENDIAN_BITMAPS
  80                         if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  81                               (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
  82                                 ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
  83 #endif
  84                         retval = io_channel_write_blk(fs->io, blk, 1,
  85                                                       bitmap_block);
  86                         if (retval)
  87                                 return EXT2_ET_INODE_BITMAP_WRITE;
  88                 }
  89                 inode_bitmap += nbytes;
  90         }
  91         fs->flags |= EXT2_FLAG_CHANGED;
  92         fs->flags &= ~EXT2_FLAG_IB_DIRTY;
  93         ext2fs_free_mem((void **) &bitmap_block);
  94         return 0;
  95 }
  96
  97 errcode_t ext2fs_write_block_bitmap (ext2_filsys fs)
  98 {
  99         dgrp_t          i;
 100         int             j;
 101         int             nbytes;
 102         int             nbits;
 103         errcode_t       retval;
 104         char * block_bitmap = fs->block_map->bitmap;
 105         char * bitmap_block = NULL;
 106         blk_t           blk;
 107
 108         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 109
 110         if (!(fs->flags & EXT2_FLAG_RW))
 111                 return EXT2_ET_RO_FILSYS;
 112         if (!block_bitmap)
 113                 return 0;
 114         nbytes = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
 115         retval = ext2fs_get_mem(fs->blocksize, (void **) &bitmap_block);
 116         if (retval)
 117                 return retval;
 118         memset(bitmap_block, 0xff, fs->blocksize);
 119         for (i = 0; i < fs->group_desc_count; i++) {
 120                 memcpy(bitmap_block, block_bitmap, nbytes);
 121                 if (i == fs->group_desc_count - 1) {
 122                         /* Force bitmap padding for the last group */
 123                         nbits = (int) ((fs->super->s_blocks_count
 124                                         - fs->super->s_first_data_block)
 125                                        % EXT2_BLOCKS_PER_GROUP(fs->super));
 126                         if (nbits)
 127                                 for (j = nbits; j < fs->blocksize * 8; j++)
 128                                         ext2fs_set_bit(j, bitmap_block);
 129                 }
 130                 blk = fs->group_desc[i].bg_block_bitmap;
 131                 if (blk) {
 132 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 133                         if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 134                               (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
 135                                 ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
 136 #endif
 137                         retval = io_channel_write_blk(fs->io, blk, 1,
 138                                                       bitmap_block);
 139                         if (retval)
 140                                 return EXT2_ET_BLOCK_BITMAP_WRITE;
 141                 }
 142                 block_bitmap += nbytes;
 143         }
 144         fs->flags |= EXT2_FLAG_CHANGED;
 145         fs->flags &= ~EXT2_FLAG_BB_DIRTY;
 146         ext2fs_free_mem((void **) &bitmap_block);
 147         return 0;
 148 }
 149
 150 static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
 151 {
 152         dgrp_t i;
 153         char *block_bitmap = 0, *inode_bitmap = 0;
 154         char *buf;
 155         errcode_t retval;
 156         int block_nbytes = (int) EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
 157         int inode_nbytes = (int) EXT2_INODES_PER_GROUP(fs->super) / 8;
 158         blk_t   blk;
 159
 160         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 161
 162         fs->write_bitmaps = ext2fs_write_bitmaps;
 163
 164         retval = ext2fs_get_mem(strlen(fs->device_name) + 80, (void **) &buf);
 165         if (retval)
 166                 return retval;
 167         if (do_block) {
 168                 if (fs->block_map)
 169                         ext2fs_free_block_bitmap(fs->block_map);
 170                 sprintf(buf, "block bitmap for %s", fs->device_name);
 171                 retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
 172                 if (retval)
 173                         goto cleanup;
 174                 block_bitmap = fs->block_map->bitmap;
 175         }
 176         if (do_inode) {
 177                 if (fs->inode_map)
 178                         ext2fs_free_inode_bitmap(fs->inode_map);
 179                 sprintf(buf, "inode bitmap for %s", fs->device_name);
 180                 retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
 181                 if (retval)
 182                         goto cleanup;
 183                 inode_bitmap = fs->inode_map->bitmap;
 184         }
 185         ext2fs_free_mem((void **) &buf);
 186
 187         if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
 188                 if (inode_bitmap) {
 189                         blk = (fs->image_header->offset_inodemap /
 190                                fs->blocksize);
 191                         retval = io_channel_read_blk(fs->io, blk,
 192                              -(inode_nbytes * fs->group_desc_count),
 193                              inode_bitmap);
 194                         if (retval)
 195                                 goto cleanup;
 196                 }
 197                 if (block_bitmap) {
 198                         blk = (fs->image_header->offset_blockmap /
 199                                fs->blocksize);
 200                         retval = io_channel_read_blk(fs->io, blk,
 201                              -(block_nbytes * fs->group_desc_count),
 202                              block_bitmap);
 203                         if (retval)
 204                                 goto cleanup;
 205                 }
 206                 return 0;
 207         }
 208
 209         for (i = 0; i < fs->group_desc_count; i++) {
 210                 if (block_bitmap) {
 211                         blk = fs->group_desc[i].bg_block_bitmap;
 212                         if (blk) {
 213                                 retval = io_channel_read_blk(fs->io, blk,
 214                                              -block_nbytes, block_bitmap);
 215                                 if (retval) {
 216                                         retval = EXT2_ET_BLOCK_BITMAP_READ;
 217                                         goto cleanup;
 218                                 }
 219 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 220                                 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 221                                       (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
 222                                         ext2fs_swap_bitmap(fs, block_bitmap, block_nbytes);
 223 #endif
 224                         } else
 225                                 memset(block_bitmap, 0, block_nbytes);
 226                         block_bitmap += block_nbytes;
 227                 }
 228                 if (inode_bitmap) {
 229                         blk = fs->group_desc[i].bg_inode_bitmap;
 230                         if (blk) {
 231                                 retval = io_channel_read_blk(fs->io, blk,
 232                                              -inode_nbytes, inode_bitmap);
 233                                 if (retval) {
 234                                         retval = EXT2_ET_INODE_BITMAP_READ;
 235                                         goto cleanup;
 236                                 }
 237 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 238                                 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 239                                       (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
 240                                         ext2fs_swap_bitmap(fs, inode_bitmap, inode_nbytes);
 241 #endif
 242                         } else
 243                                 memset(inode_bitmap, 0, inode_nbytes);
 244                         inode_bitmap += inode_nbytes;
 245                 }
 246         }
 247         return 0;
 248
 249 cleanup:
 250         if (do_block) {
 251                 ext2fs_free_mem((void **) &fs->block_map);
 252                 fs->block_map = 0;
 253         }
 254         if (do_inode) {
 255                 ext2fs_free_mem((void **) &fs->inode_map);
 256                 fs->inode_map = 0;
 257         }
 258         if (buf)
 259                 ext2fs_free_mem((void **) &buf);
 260         return retval;
 261 }
 262
 263 errcode_t ext2fs_read_inode_bitmap (ext2_filsys fs)
 264 {
 265         return read_bitmaps(fs, 1, 0);
 266 }
 267
 268 errcode_t ext2fs_read_block_bitmap(ext2_filsys fs)
 269 {
 270         return read_bitmaps(fs, 0, 1);
 271 }
 272
 273 errcode_t ext2fs_read_bitmaps(ext2_filsys fs)
 274 {
 275
 276         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 277
 278         if (fs->inode_map && fs->block_map)
 279                 return 0;
 280
 281         return read_bitmaps(fs, !fs->inode_map, !fs->block_map);
 282 }
 283
 284 errcode_t ext2fs_write_bitmaps(ext2_filsys fs)
 285 {
 286         errcode_t       retval;
 287
 288         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 289
 290         if (fs->block_map && ext2fs_test_bb_dirty(fs)) {
 291                 retval = ext2fs_write_block_bitmap(fs);
 292                 if (retval)
 293                         return retval;
 294         }
 295         if (fs->inode_map && ext2fs_test_ib_dirty(fs)) {
 296                 retval = ext2fs_write_inode_bitmap(fs);
 297                 if (retval)
 298                         return retval;
 299         }
 300         return 0;
 301 }
 302