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 static 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, &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_IB_DIRTY;
  92         ext2fs_free_mem(&bitmap_block);
  93         return 0;
  94 }
  95
  96 errcode_t ext2fs_write_block_bitmap (ext2_filsys fs)
  97 {
  98         dgrp_t          i;
  99         unsigned int    j;
 100         int             nbytes;
 101         unsigned int    nbits;
 102         errcode_t       retval;
 103         char * block_bitmap = fs->block_map->bitmap;
 104         char * bitmap_block = NULL;
 105         blk_t           blk;
 106
 107         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 108
 109         if (!(fs->flags & EXT2_FLAG_RW))
 110                 return EXT2_ET_RO_FILSYS;
 111         if (!block_bitmap)
 112                 return 0;
 113         nbytes = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
 114         retval = ext2fs_get_mem(fs->blocksize, &bitmap_block);
 115         if (retval)
 116                 return retval;
 117         memset(bitmap_block, 0xff, fs->blocksize);
 118         for (i = 0; i < fs->group_desc_count; i++) {
 119                 memcpy(bitmap_block, block_bitmap, nbytes);
 120                 if (i == fs->group_desc_count - 1) {
 121                         /* Force bitmap padding for the last group */
 122                         nbits = ((fs->super->s_blocks_count
 123                                   - fs->super->s_first_data_block)
 124                                  % EXT2_BLOCKS_PER_GROUP(fs->super));
 125                         if (nbits)
 126                                 for (j = nbits; j < fs->blocksize * 8; j++)
 127                                         ext2fs_set_bit(j, bitmap_block);
 128                 }
 129                 blk = fs->group_desc[i].bg_block_bitmap;
 130                 if (blk) {
 131 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 132                         if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 133                               (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
 134                                 ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
 135 #endif
 136                         retval = io_channel_write_blk(fs->io, blk, 1,
 137                                                       bitmap_block);
 138                         if (retval)
 139                                 return EXT2_ET_BLOCK_BITMAP_WRITE;
 140                 }
 141                 block_bitmap += nbytes;
 142         }
 143         fs->flags &= ~EXT2_FLAG_BB_DIRTY;
 144         ext2fs_free_mem(&bitmap_block);
 145         return 0;
 146 }
 147
 148 static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
 149 {
 150         dgrp_t i;
 151         char *block_bitmap = 0, *inode_bitmap = 0;
 152         char *buf;
 153         errcode_t retval;
 154         int block_nbytes = (int) EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
 155         int inode_nbytes = (int) EXT2_INODES_PER_GROUP(fs->super) / 8;
 156         blk_t   blk;
 157
 158         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 159
 160         fs->write_bitmaps = ext2fs_write_bitmaps;
 161
 162         retval = ext2fs_get_mem(strlen(fs->device_name) + 80, &buf);
 163         if (retval)
 164                 return retval;
 165         if (do_block) {
 166                 if (fs->block_map)
 167                         ext2fs_free_block_bitmap(fs->block_map);
 168                 sprintf(buf, "block bitmap for %s", fs->device_name);
 169                 retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
 170                 if (retval)
 171                         goto cleanup;
 172                 block_bitmap = fs->block_map->bitmap;
 173         }
 174         if (do_inode) {
 175                 if (fs->inode_map)
 176                         ext2fs_free_inode_bitmap(fs->inode_map);
 177                 sprintf(buf, "inode bitmap for %s", fs->device_name);
 178                 retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
 179                 if (retval)
 180                         goto cleanup;
 181                 inode_bitmap = fs->inode_map->bitmap;
 182         }
 183         ext2fs_free_mem(&buf);
 184
 185         if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
 186                 if (inode_bitmap) {
 187                         blk = (fs->image_header->offset_inodemap /
 188                                fs->blocksize);
 189                         retval = io_channel_read_blk(fs->io, blk,
 190                              -(inode_nbytes * fs->group_desc_count),
 191                              inode_bitmap);
 192                         if (retval)
 193                                 goto cleanup;
 194                 }
 195                 if (block_bitmap) {
 196                         blk = (fs->image_header->offset_blockmap /
 197                                fs->blocksize);
 198                         retval = io_channel_read_blk(fs->io, blk,
 199                              -(block_nbytes * fs->group_desc_count),
 200                              block_bitmap);
 201                         if (retval)
 202                                 goto cleanup;
 203                 }
 204                 return 0;
 205         }
 206
 207         for (i = 0; i < fs->group_desc_count; i++) {
 208                 if (block_bitmap) {
 209                         blk = fs->group_desc[i].bg_block_bitmap;
 210                         if (blk) {
 211                                 retval = io_channel_read_blk(fs->io, blk,
 212                                              -block_nbytes, block_bitmap);
 213                                 if (retval) {
 214                                         retval = EXT2_ET_BLOCK_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, block_bitmap, block_nbytes);
 221 #endif
 222                         } else
 223                                 memset(block_bitmap, 0, block_nbytes);
 224                         block_bitmap += block_nbytes;
 225                 }
 226                 if (inode_bitmap) {
 227                         blk = fs->group_desc[i].bg_inode_bitmap;
 228                         if (blk) {
 229                                 retval = io_channel_read_blk(fs->io, blk,
 230                                              -inode_nbytes, inode_bitmap);
 231                                 if (retval) {
 232                                         retval = EXT2_ET_INODE_BITMAP_READ;
 233                                         goto cleanup;
 234                                 }
 235 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 236                                 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 237                                       (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
 238                                         ext2fs_swap_bitmap(fs, inode_bitmap, inode_nbytes);
 239 #endif
 240                         } else
 241                                 memset(inode_bitmap, 0, inode_nbytes);
 242                         inode_bitmap += inode_nbytes;
 243                 }
 244         }
 245         return 0;
 246
 247 cleanup:
 248         if (do_block) {
 249                 ext2fs_free_mem(&fs->block_map);
 250                 fs->block_map = 0;
 251         }
 252         if (do_inode) {
 253                 ext2fs_free_mem(&fs->inode_map);
 254                 fs->inode_map = 0;
 255         }
 256         if (buf)
 257                 ext2fs_free_mem(&buf);
 258         return retval;
 259 }
 260
 261 errcode_t ext2fs_read_inode_bitmap (ext2_filsys fs)
 262 {
 263         return read_bitmaps(fs, 1, 0);
 264 }
 265
 266 errcode_t ext2fs_read_block_bitmap(ext2_filsys fs)
 267 {
 268         return read_bitmaps(fs, 0, 1);
 269 }
 270
 271 errcode_t ext2fs_read_bitmaps(ext2_filsys fs)
 272 {
 273
 274         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 275
 276         if (fs->inode_map && fs->block_map)
 277                 return 0;
 278
 279         return read_bitmaps(fs, !fs->inode_map, !fs->block_map);
 280 }
 281
 282 errcode_t ext2fs_write_bitmaps(ext2_filsys fs)
 283 {
 284         errcode_t       retval;
 285
 286         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 287
 288         if (fs->block_map && ext2fs_test_bb_dirty(fs)) {
 289                 retval = ext2fs_write_block_bitmap(fs);
 290                 if (retval)
 291                         return retval;
 292         }
 293         if (fs->inode_map && ext2fs_test_ib_dirty(fs)) {
 294                 retval = ext2fs_write_inode_bitmap(fs);
 295                 if (retval)
 296                         return retval;
 297         }
 298         return 0;
 299 }
 300