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 static errcode_t write_bitmaps(ext2_filsys fs, int do_inode, int do_block)
  55 {
  56         dgrp_t          i;
  57         unsigned int    j;
  58         int             block_nbytes, inode_nbytes;
  59         unsigned int    nbits;
  60         errcode_t       retval;
  61         char            *block_bitmap, *inode_bitmap;
  62         char            *block_buf, *inode_buf;
  63         int             lazy_flag = 0;
  64         blk_t           blk;
  65
  66         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  67
  68         if (!(fs->flags & EXT2_FLAG_RW))
  69                 return EXT2_ET_RO_FILSYS;
  70         if (EXT2_HAS_COMPAT_FEATURE(fs->super,
  71                                     EXT2_FEATURE_COMPAT_LAZY_BG))
  72                 lazy_flag = 1;
  73         inode_nbytes = block_nbytes = 0;
  74         block_bitmap = inode_bitmap = 0;
  75         if (do_block) {
  76                 block_bitmap = fs->block_map->bitmap;
  77                 block_nbytes = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
  78                 retval = ext2fs_get_mem(fs->blocksize, &block_buf);
  79                 if (retval)
  80                         return retval;
  81                 memset(block_buf, 0xff, fs->blocksize);
  82         }
  83         if (do_inode) {
  84                 inode_bitmap = fs->inode_map->bitmap;
  85                 inode_nbytes = (size_t)
  86                         ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
  87                 retval = ext2fs_get_mem(fs->blocksize, &inode_buf);
  88                 if (retval)
  89                         return retval;
  90                 memset(inode_buf, 0xff, fs->blocksize);
  91         }
  92
  93         for (i = 0; i < fs->group_desc_count; i++) {
  94                 if (!block_bitmap || !do_block)
  95                         goto skip_block_bitmap;
  96
  97                 if (lazy_flag && fs->group_desc[i].bg_flags &
  98                     EXT2_BG_BLOCK_UNINIT)
  99                         goto skip_this_block_bitmap;
 100
 101                 memcpy(block_buf, block_bitmap, block_nbytes);
 102                 if (i == fs->group_desc_count - 1) {
 103                         /* Force bitmap padding for the last group */
 104                         nbits = ((fs->super->s_blocks_count
 105                                   - fs->super->s_first_data_block)
 106                                  % EXT2_BLOCKS_PER_GROUP(fs->super));
 107                         if (nbits)
 108                                 for (j = nbits; j < fs->blocksize * 8; j++)
 109                                         ext2fs_set_bit(j, block_buf);
 110                 }
 111                 blk = fs->group_desc[i].bg_block_bitmap;
 112                 if (blk) {
 113 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 114                         if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 115                               (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
 116                                 ext2fs_swap_bitmap(fs, block_buf,
 117                                                    block_nbytes);
 118 #endif
 119                         retval = io_channel_write_blk(fs->io, blk, 1,
 120                                                       block_buf);
 121                         if (retval)
 122                                 return EXT2_ET_BLOCK_BITMAP_WRITE;
 123                 }
 124         skip_this_block_bitmap:
 125                 block_bitmap += block_nbytes;
 126         skip_block_bitmap:
 127
 128                 if (!inode_bitmap || !do_inode)
 129                         continue;
 130
 131                 if (lazy_flag && fs->group_desc[i].bg_flags &
 132                     EXT2_BG_INODE_UNINIT)
 133                         goto skip_this_inode_bitmap;
 134
 135                 memcpy(inode_buf, inode_bitmap, inode_nbytes);
 136                 blk = fs->group_desc[i].bg_inode_bitmap;
 137                 if (blk) {
 138 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 139                         if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 140                               (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
 141                                 ext2fs_swap_bitmap(fs, inode_buf,
 142                                                    inode_nbytes);
 143 #endif
 144                         retval = io_channel_write_blk(fs->io, blk, 1,
 145                                                       inode_buf);
 146                         if (retval)
 147                                 return EXT2_ET_INODE_BITMAP_WRITE;
 148                 }
 149         skip_this_inode_bitmap:
 150                 inode_bitmap += inode_nbytes;
 151
 152         }
 153         if (do_block) {
 154                 fs->flags &= ~EXT2_FLAG_BB_DIRTY;
 155                 ext2fs_free_mem(&block_buf);
 156         }
 157         if (do_inode) {
 158                 fs->flags &= ~EXT2_FLAG_IB_DIRTY;
 159                 ext2fs_free_mem(&inode_buf);
 160         }
 161         return 0;
 162 }
 163
 164 static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
 165 {
 166         dgrp_t i;
 167         char *block_bitmap = 0, *inode_bitmap = 0;
 168         char *buf;
 169         errcode_t retval;
 170         int block_nbytes = (int) EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
 171         int inode_nbytes = (int) EXT2_INODES_PER_GROUP(fs->super) / 8;
 172         int lazy_flag = 0;
 173         blk_t   blk;
 174
 175         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 176
 177         fs->write_bitmaps = ext2fs_write_bitmaps;
 178
 179         if (EXT2_HAS_COMPAT_FEATURE(fs->super,
 180                                     EXT2_FEATURE_COMPAT_LAZY_BG))
 181                 lazy_flag = 1;
 182
 183         retval = ext2fs_get_mem(strlen(fs->device_name) + 80, &buf);
 184         if (retval)
 185                 return retval;
 186         if (do_block) {
 187                 if (fs->block_map)
 188                         ext2fs_free_block_bitmap(fs->block_map);
 189                 sprintf(buf, "block bitmap for %s", fs->device_name);
 190                 retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
 191                 if (retval)
 192                         goto cleanup;
 193                 block_bitmap = fs->block_map->bitmap;
 194         }
 195         if (do_inode) {
 196                 if (fs->inode_map)
 197                         ext2fs_free_inode_bitmap(fs->inode_map);
 198                 sprintf(buf, "inode bitmap for %s", fs->device_name);
 199                 retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
 200                 if (retval)
 201                         goto cleanup;
 202                 inode_bitmap = fs->inode_map->bitmap;
 203         }
 204         ext2fs_free_mem(&buf);
 205
 206         if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
 207                 if (inode_bitmap) {
 208                         blk = (fs->image_header->offset_inodemap /
 209                                fs->blocksize);
 210                         retval = io_channel_read_blk(fs->image_io, blk,
 211                              -(inode_nbytes * fs->group_desc_count),
 212                              inode_bitmap);
 213                         if (retval)
 214                                 goto cleanup;
 215                 }
 216                 if (block_bitmap) {
 217                         blk = (fs->image_header->offset_blockmap /
 218                                fs->blocksize);
 219                         retval = io_channel_read_blk(fs->image_io, blk,
 220                              -(block_nbytes * fs->group_desc_count),
 221                              block_bitmap);
 222                         if (retval)
 223                                 goto cleanup;
 224                 }
 225                 return 0;
 226         }
 227
 228         for (i = 0; i < fs->group_desc_count; i++) {
 229                 if (block_bitmap) {
 230                         blk = fs->group_desc[i].bg_block_bitmap;
 231                         if (lazy_flag && fs->group_desc[i].bg_flags &
 232                             EXT2_BG_BLOCK_UNINIT)
 233                                 blk = 0;
 234                         if (blk) {
 235                                 retval = io_channel_read_blk(fs->io, blk,
 236                                              -block_nbytes, block_bitmap);
 237                                 if (retval) {
 238                                         retval = EXT2_ET_BLOCK_BITMAP_READ;
 239                                         goto cleanup;
 240                                 }
 241 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 242                                 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 243                                       (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
 244                                         ext2fs_swap_bitmap(fs, block_bitmap, block_nbytes);
 245 #endif
 246                         } else
 247                                 memset(block_bitmap, 0xff, block_nbytes);
 248                         block_bitmap += block_nbytes;
 249                 }
 250                 if (inode_bitmap) {
 251                         blk = fs->group_desc[i].bg_inode_bitmap;
 252                         if (lazy_flag && fs->group_desc[i].bg_flags &
 253                             EXT2_BG_INODE_UNINIT)
 254                                 blk = 0;
 255                         if (blk) {
 256                                 retval = io_channel_read_blk(fs->io, blk,
 257                                              -inode_nbytes, inode_bitmap);
 258                                 if (retval) {
 259                                         retval = EXT2_ET_INODE_BITMAP_READ;
 260                                         goto cleanup;
 261                                 }
 262 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 263                                 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 264                                       (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
 265                                         ext2fs_swap_bitmap(fs, inode_bitmap, inode_nbytes);
 266 #endif
 267                         } else
 268                                 memset(inode_bitmap, 0xff, inode_nbytes);
 269                         inode_bitmap += inode_nbytes;
 270                 }
 271         }
 272         return 0;
 273
 274 cleanup:
 275         if (do_block) {
 276                 ext2fs_free_mem(&fs->block_map);
 277                 fs->block_map = 0;
 278         }
 279         if (do_inode) {
 280                 ext2fs_free_mem(&fs->inode_map);
 281                 fs->inode_map = 0;
 282         }
 283         if (buf)
 284                 ext2fs_free_mem(&buf);
 285         return retval;
 286 }
 287
 288 errcode_t ext2fs_read_inode_bitmap(ext2_filsys fs)
 289 {
 290         return read_bitmaps(fs, 1, 0);
 291 }
 292
 293 errcode_t ext2fs_read_block_bitmap(ext2_filsys fs)
 294 {
 295         return read_bitmaps(fs, 0, 1);
 296 }
 297
 298 errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs)
 299 {
 300         return write_bitmaps(fs, 1, 0);
 301 }
 302
 303 errcode_t ext2fs_write_block_bitmap (ext2_filsys fs)
 304 {
 305         return write_bitmaps(fs, 0, 1);
 306 }
 307
 308 errcode_t ext2fs_read_bitmaps(ext2_filsys fs)
 309 {
 310         if (fs->inode_map && fs->block_map)
 311                 return 0;
 312
 313         return read_bitmaps(fs, !fs->inode_map, !fs->block_map);
 314 }
 315
 316 errcode_t ext2fs_write_bitmaps(ext2_filsys fs)
 317 {
 318         int do_inode = fs->inode_map && ext2fs_test_ib_dirty(fs);
 319         int do_block = fs->block_map && ext2fs_test_bb_dirty(fs);
 320
 321         if (!do_inode && !do_block)
 322                 return 0;
 323
 324         return write_bitmaps(fs, do_inode, do_block);
 325 }