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_buf, *inode_buf;
  62         int             lazy_flag = 0;
  63         blk_t           blk;
  64         blk_t           blk_itr = fs->super->s_first_data_block;
  65         ext2_ino_t      ino_itr = 1;
  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 (EXT2_HAS_COMPAT_FEATURE(fs->super,
  72                                     EXT2_FEATURE_COMPAT_LAZY_BG))
  73                 lazy_flag = 1;
  74         inode_nbytes = block_nbytes = 0;
  75         if (do_block) {
  76                 block_nbytes = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
  77                 retval = ext2fs_get_mem(fs->blocksize, &block_buf);
  78                 if (retval)
  79                         return retval;
  80                 memset(block_buf, 0xff, fs->blocksize);
  81         }
  82         if (do_inode) {
  83                 inode_nbytes = (size_t)
  84                         ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
  85                 retval = ext2fs_get_mem(fs->blocksize, &inode_buf);
  86                 if (retval)
  87                         return retval;
  88                 memset(inode_buf, 0xff, fs->blocksize);
  89         }
  90
  91         for (i = 0; i < fs->group_desc_count; i++) {
  92                 if (!do_block)
  93                         goto skip_block_bitmap;
  94
  95                 if (lazy_flag && fs->group_desc[i].bg_flags &
  96                     EXT2_BG_BLOCK_UNINIT)
  97                         goto skip_this_block_bitmap;
  98
  99                 retval = ext2fs_get_block_bitmap_range(fs->block_map,
 100                                 blk_itr, block_nbytes << 3, block_buf);
 101                 if (retval)
 102                         return retval;
 103
 104                 if (i == fs->group_desc_count - 1) {
 105                         /* Force bitmap padding for the last group */
 106                         nbits = ((fs->super->s_blocks_count
 107                                   - fs->super->s_first_data_block)
 108                                  % EXT2_BLOCKS_PER_GROUP(fs->super));
 109                         if (nbits)
 110                                 for (j = nbits; j < fs->blocksize * 8; j++)
 111                                         ext2fs_set_bit(j, block_buf);
 112                 }
 113                 blk = fs->group_desc[i].bg_block_bitmap;
 114                 if (blk) {
 115 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 116                         if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 117                               (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
 118                                 ext2fs_swap_bitmap(fs, block_buf,
 119                                                    block_nbytes);
 120 #endif
 121                         retval = io_channel_write_blk(fs->io, blk, 1,
 122                                                       block_buf);
 123                         if (retval)
 124                                 return EXT2_ET_BLOCK_BITMAP_WRITE;
 125                 }
 126         skip_this_block_bitmap:
 127                 blk_itr += block_nbytes << 3;
 128         skip_block_bitmap:
 129
 130                 if (!do_inode)
 131                         continue;
 132
 133                 if (lazy_flag && fs->group_desc[i].bg_flags &
 134                     EXT2_BG_INODE_UNINIT)
 135                         goto skip_this_inode_bitmap;
 136
 137                 retval = ext2fs_get_inode_bitmap_range(fs->inode_map,
 138                                 ino_itr, inode_nbytes << 3, inode_buf);
 139                 if (retval)
 140                         return retval;
 141
 142                 blk = fs->group_desc[i].bg_inode_bitmap;
 143                 if (blk) {
 144 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 145                         if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 146                               (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
 147                                 ext2fs_swap_bitmap(fs, inode_buf,
 148                                                    inode_nbytes);
 149 #endif
 150                         retval = io_channel_write_blk(fs->io, blk, 1,
 151                                                       inode_buf);
 152                         if (retval)
 153                                 return EXT2_ET_INODE_BITMAP_WRITE;
 154                 }
 155         skip_this_inode_bitmap:
 156                 ino_itr += inode_nbytes << 3;
 157
 158         }
 159         if (do_block) {
 160                 fs->flags &= ~EXT2_FLAG_BB_DIRTY;
 161                 ext2fs_free_mem(&block_buf);
 162         }
 163         if (do_inode) {
 164                 fs->flags &= ~EXT2_FLAG_IB_DIRTY;
 165                 ext2fs_free_mem(&inode_buf);
 166         }
 167         return 0;
 168 }
 169
 170 static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
 171 {
 172         dgrp_t i;
 173         char *block_bitmap = 0, *inode_bitmap = 0;
 174         char *buf;
 175         errcode_t retval;
 176         unsigned int block_nbytes = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
 177         unsigned inode_nbytes = EXT2_INODES_PER_GROUP(fs->super) / 8;
 178         int lazy_flag = 0;
 179         int do_image = fs->flags & EXT2_FLAG_IMAGE_FILE;
 180         unsigned int    cnt;
 181         blk_t   blk;
 182         blk_t   blk_itr = fs->super->s_first_data_block;
 183         blk_t   blk_cnt;
 184         ext2_ino_t ino_itr = 1;
 185         ext2_ino_t ino_cnt;
 186
 187         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 188
 189         fs->write_bitmaps = ext2fs_write_bitmaps;
 190
 191         if (EXT2_HAS_COMPAT_FEATURE(fs->super,
 192                                     EXT2_FEATURE_COMPAT_LAZY_BG))
 193                 lazy_flag = 1;
 194
 195         retval = ext2fs_get_mem(strlen(fs->device_name) + 80, &buf);
 196         if (retval)
 197                 return retval;
 198         if (do_block) {
 199                 if (fs->block_map)
 200                         ext2fs_free_block_bitmap(fs->block_map);
 201                 sprintf(buf, "block bitmap for %s", fs->device_name);
 202                 retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
 203                 if (retval)
 204                         goto cleanup;
 205                 retval = ext2fs_get_mem(do_image ? fs->blocksize :
 206                                         block_nbytes, &block_bitmap);
 207                 if (retval)
 208                         goto cleanup;
 209         } else
 210                 block_nbytes = 0;
 211         if (do_inode) {
 212                 if (fs->inode_map)
 213                         ext2fs_free_inode_bitmap(fs->inode_map);
 214                 sprintf(buf, "inode bitmap for %s", fs->device_name);
 215                 retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
 216                 if (retval)
 217                         goto cleanup;
 218                 retval = ext2fs_get_mem(do_image ? fs->blocksize :
 219                                         inode_nbytes, &inode_bitmap);
 220                 if (retval)
 221                         goto cleanup;
 222         } else
 223                 inode_nbytes = 0;
 224         ext2fs_free_mem(&buf);
 225
 226         if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
 227                 blk = (fs->image_header->offset_inodemap / fs->blocksize);
 228                 ino_cnt = fs->super->s_inodes_count;
 229                 while (inode_nbytes > 0) {
 230                         retval = io_channel_read_blk(fs->image_io, blk++,
 231                                                      1, inode_bitmap);
 232                         if (retval)
 233                                 goto cleanup;
 234                         cnt = fs->blocksize << 3;
 235                         if (cnt > ino_cnt)
 236                                 cnt = ino_cnt;
 237                         retval = ext2fs_set_inode_bitmap_range(fs->inode_map,
 238                                                ino_itr, cnt, inode_bitmap);
 239                         if (retval)
 240                                 goto cleanup;
 241                         ino_itr += fs->blocksize << 3;
 242                         ino_cnt -= fs->blocksize << 3;
 243                         inode_nbytes -= fs->blocksize;
 244                 }
 245                 blk = (fs->image_header->offset_blockmap /
 246                        fs->blocksize);
 247                 blk_cnt = EXT2_BLOCKS_PER_GROUP(fs->super) *
 248                         fs->group_desc_count;
 249                 while (block_nbytes > 0) {
 250                         retval = io_channel_read_blk(fs->image_io, blk++,
 251                                                      1, block_bitmap);
 252                         if (retval)
 253                                 goto cleanup;
 254                         cnt = fs->blocksize << 3;
 255                         if (cnt > blk_cnt)
 256                                 cnt = blk_cnt;
 257                         retval = ext2fs_set_block_bitmap_range(fs->block_map,
 258                                        blk_itr, cnt, block_bitmap);
 259                         if (retval)
 260                                 goto cleanup;
 261                         blk_itr += fs->blocksize << 3;
 262                         blk_cnt -= fs->blocksize << 3;
 263                         block_nbytes -= fs->blocksize;
 264                 }
 265                 goto success_cleanup;
 266         }
 267
 268         for (i = 0; i < fs->group_desc_count; i++) {
 269                 if (block_bitmap) {
 270                         blk = fs->group_desc[i].bg_block_bitmap;
 271                         if (lazy_flag && fs->group_desc[i].bg_flags &
 272                             EXT2_BG_BLOCK_UNINIT)
 273                                 blk = 0;
 274                         if (blk) {
 275                                 retval = io_channel_read_blk(fs->io, blk,
 276                                              -block_nbytes, block_bitmap);
 277                                 if (retval) {
 278                                         retval = EXT2_ET_BLOCK_BITMAP_READ;
 279                                         goto cleanup;
 280                                 }
 281 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 282                                 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 283                                       (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
 284                                         ext2fs_swap_bitmap(fs, block_bitmap, block_nbytes);
 285 #endif
 286                         } else
 287                                 memset(block_bitmap, 0xff, block_nbytes);
 288                         cnt = block_nbytes << 3;
 289                         retval = ext2fs_set_block_bitmap_range(fs->block_map,
 290                                                blk_itr, cnt, block_bitmap);
 291                         if (retval)
 292                                 goto cleanup;
 293                         blk_itr += block_nbytes << 3;
 294                 }
 295                 if (inode_bitmap) {
 296                         blk = fs->group_desc[i].bg_inode_bitmap;
 297                         if (lazy_flag && fs->group_desc[i].bg_flags &
 298                             EXT2_BG_INODE_UNINIT)
 299                                 blk = 0;
 300                         if (blk) {
 301                                 retval = io_channel_read_blk(fs->io, blk,
 302                                              -inode_nbytes, inode_bitmap);
 303                                 if (retval) {
 304                                         retval = EXT2_ET_INODE_BITMAP_READ;
 305                                         goto cleanup;
 306                                 }
 307 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 308                                 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 309                                       (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
 310                                         ext2fs_swap_bitmap(fs, inode_bitmap, inode_nbytes);
 311 #endif
 312                         } else
 313                                 memset(inode_bitmap, 0xff, inode_nbytes);
 314                         cnt = inode_nbytes << 3;
 315                         retval = ext2fs_set_inode_bitmap_range(fs->inode_map,
 316                                                ino_itr, cnt, inode_bitmap);
 317                         if (retval)
 318                                 goto cleanup;
 319                         ino_itr += inode_nbytes << 3;
 320                 }
 321         }
 322 success_cleanup:
 323         if (inode_bitmap)
 324                 ext2fs_free_mem(&inode_bitmap);
 325         if (block_bitmap)
 326                 ext2fs_free_mem(&block_bitmap);
 327         return 0;
 328
 329 cleanup:
 330         if (do_block) {
 331                 ext2fs_free_mem(&fs->block_map);
 332                 fs->block_map = 0;
 333         }
 334         if (do_inode) {
 335                 ext2fs_free_mem(&fs->inode_map);
 336                 fs->inode_map = 0;
 337         }
 338         if (inode_bitmap)
 339                 ext2fs_free_mem(&inode_bitmap);
 340         if (block_bitmap)
 341                 ext2fs_free_mem(&block_bitmap);
 342         if (buf)
 343                 ext2fs_free_mem(&buf);
 344         return retval;
 345 }
 346
 347 errcode_t ext2fs_read_inode_bitmap(ext2_filsys fs)
 348 {
 349         return read_bitmaps(fs, 1, 0);
 350 }
 351
 352 errcode_t ext2fs_read_block_bitmap(ext2_filsys fs)
 353 {
 354         return read_bitmaps(fs, 0, 1);
 355 }
 356
 357 errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs)
 358 {
 359         return write_bitmaps(fs, 1, 0);
 360 }
 361
 362 errcode_t ext2fs_write_block_bitmap (ext2_filsys fs)
 363 {
 364         return write_bitmaps(fs, 0, 1);
 365 }
 366
 367 errcode_t ext2fs_read_bitmaps(ext2_filsys fs)
 368 {
 369         if (fs->inode_map && fs->block_map)
 370                 return 0;
 371
 372         return read_bitmaps(fs, !fs->inode_map, !fs->block_map);
 373 }
 374
 375 errcode_t ext2fs_write_bitmaps(ext2_filsys fs)
 376 {
 377         int do_inode = fs->inode_map && ext2fs_test_ib_dirty(fs);
 378         int do_block = fs->block_map && ext2fs_test_bb_dirty(fs);
 379
 380         if (!do_inode && !do_block)
 381                 return 0;
 382
 383         return write_bitmaps(fs, do_inode, do_block);
 384 }