release/src/router/busybox/e2fsprogs/ext2fs/rw_bitmaps.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * rw_bitmaps.c --- routines to read and write the  inode and block bitmaps.
   4  *
   5  * Copyright (C) 1993, 1994, 1994, 1996 Theodore Ts'o.
   6  *
   7  * %Begin-Header%
   8  * This file may be redistributed under the terms of the GNU Public
   9  * License.
  10  * %End-Header%
  11  */
  12
  13 #include <stdio.h>
  14 #include <string.h>
  15 #if HAVE_UNISTD_H
  16 #include <unistd.h>
  17 #endif
  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
  27 #include "ext2_fs.h"
  28 #include "ext2fs.h"
  29 #include "e2image.h"
  30
  31 #if defined(__powerpc__) && BB_BIG_ENDIAN
  32 /*
  33  * On the PowerPC, the big-endian variant of the ext2 filesystem
  34  * has its bitmaps stored as 32-bit words with bit 0 as the LSB
  35  * of each word.  Thus a bitmap with only bit 0 set would be, as
  36  * a string of bytes, 00 00 00 01 00 ...
  37  * To cope with this, we byte-reverse each word of a bitmap if
  38  * we have a big-endian filesystem, that is, if we are *not*
  39  * byte-swapping other word-sized numbers.
  40  */
  41 #define EXT2_BIG_ENDIAN_BITMAPS
  42 #endif
  43
  44 #ifdef EXT2_BIG_ENDIAN_BITMAPS
  45 static void ext2fs_swap_bitmap(ext2_filsys fs, char *bitmap, int nbytes)
  46 {
  47         __u32 *p = (__u32 *) bitmap;
  48         int n;
  49
  50         for (n = nbytes / sizeof(__u32); n > 0; --n, ++p)
  51                 *p = ext2fs_swab32(*p);
  52 }
  53 #endif
  54
  55 errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs)
  56 {
  57         dgrp_t          i;
  58         size_t          nbytes;
  59         errcode_t       retval;
  60         char * inode_bitmap = fs->inode_map->bitmap;
  61         char * bitmap_block = NULL;
  62         blk_t           blk;
  63
  64         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  65
  66         if (!(fs->flags & EXT2_FLAG_RW))
  67                 return EXT2_ET_RO_FILSYS;
  68         if (!inode_bitmap)
  69                 return 0;
  70         nbytes = (size_t) ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
  71
  72         retval = ext2fs_get_mem(fs->blocksize, &bitmap_block);
  73         if (retval)
  74                 return retval;
  75         memset(bitmap_block, 0xff, fs->blocksize);
  76         for (i = 0; i < fs->group_desc_count; i++) {
  77                 memcpy(bitmap_block, inode_bitmap, nbytes);
  78                 blk = fs->group_desc[i].bg_inode_bitmap;
  79                 if (blk) {
  80 #ifdef EXT2_BIG_ENDIAN_BITMAPS
  81                         if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  82                               (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
  83                                 ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
  84 #endif
  85                         retval = io_channel_write_blk(fs->io, blk, 1,
  86                                                       bitmap_block);
  87                         if (retval)
  88                                 return EXT2_ET_INODE_BITMAP_WRITE;
  89                 }
  90                 inode_bitmap += nbytes;
  91         }
  92         fs->flags &= ~EXT2_FLAG_IB_DIRTY;
  93         ext2fs_free_mem(&bitmap_block);
  94         return 0;
  95 }
  96
  97 errcode_t ext2fs_write_block_bitmap (ext2_filsys fs)
  98 {
  99         dgrp_t          i;
 100         unsigned int    j;
 101         int             nbytes;
 102         unsigned 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, &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 = ((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_BB_DIRTY;
 145         ext2fs_free_mem(&bitmap_block);
 146         return 0;
 147 }
 148
 149 static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
 150 {
 151         dgrp_t i;
 152         char *block_bitmap = NULL, *inode_bitmap = NULL;
 153         char *buf;
 154         errcode_t retval;
 155         int block_nbytes = (int) EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
 156         int inode_nbytes = (int) EXT2_INODES_PER_GROUP(fs->super) / 8;
 157         blk_t   blk;
 158
 159         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 160
 161         fs->write_bitmaps = ext2fs_write_bitmaps;
 162
 163         retval = ext2fs_get_mem(strlen(fs->device_name) + 80, &buf);
 164         if (retval)
 165                 return retval;
 166         if (do_block) {
 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                 ext2fs_free_inode_bitmap(fs->inode_map);
 176                 sprintf(buf, "inode bitmap for %s", fs->device_name);
 177                 retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
 178                 if (retval)
 179                         goto cleanup;
 180                 inode_bitmap = fs->inode_map->bitmap;
 181         }
 182         ext2fs_free_mem(&buf);
 183
 184         if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
 185                 if (inode_bitmap) {
 186                         blk = (fs->image_header->offset_inodemap /
 187                                fs->blocksize);
 188                         retval = io_channel_read_blk(fs->image_io, blk,
 189                              -(inode_nbytes * fs->group_desc_count),
 190                              inode_bitmap);
 191                         if (retval)
 192                                 goto cleanup;
 193                 }
 194                 if (block_bitmap) {
 195                         blk = (fs->image_header->offset_blockmap /
 196                                fs->blocksize);
 197                         retval = io_channel_read_blk(fs->image_io, blk,
 198                              -(block_nbytes * fs->group_desc_count),
 199                              block_bitmap);
 200                         if (retval)
 201                                 goto cleanup;
 202                 }
 203                 return 0;
 204         }
 205
 206         for (i = 0; i < fs->group_desc_count; i++) {
 207                 if (block_bitmap) {
 208                         blk = fs->group_desc[i].bg_block_bitmap;
 209                         if (blk) {
 210                                 retval = io_channel_read_blk(fs->io, blk,
 211                                              -block_nbytes, block_bitmap);
 212                                 if (retval) {
 213                                         retval = EXT2_ET_BLOCK_BITMAP_READ;
 214                                         goto cleanup;
 215                                 }
 216 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 217                                 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 218                                       (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
 219                                         ext2fs_swap_bitmap(fs, block_bitmap, block_nbytes);
 220 #endif
 221                         } else
 222                                 memset(block_bitmap, 0, block_nbytes);
 223                         block_bitmap += block_nbytes;
 224                 }
 225                 if (inode_bitmap) {
 226                         blk = fs->group_desc[i].bg_inode_bitmap;
 227                         if (blk) {
 228                                 retval = io_channel_read_blk(fs->io, blk,
 229                                              -inode_nbytes, inode_bitmap);
 230                                 if (retval) {
 231                                         retval = EXT2_ET_INODE_BITMAP_READ;
 232                                         goto cleanup;
 233                                 }
 234 #ifdef EXT2_BIG_ENDIAN_BITMAPS
 235                                 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
 236                                       (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
 237                                         ext2fs_swap_bitmap(fs, inode_bitmap, inode_nbytes);
 238 #endif
 239                         } else
 240                                 memset(inode_bitmap, 0, inode_nbytes);
 241                         inode_bitmap += inode_nbytes;
 242                 }
 243         }
 244         return 0;
 245
 246 cleanup:
 247         if (do_block) {
 248                 ext2fs_free_mem(&fs->block_map);
 249         }
 250         if (do_inode) {
 251                 ext2fs_free_mem(&fs->inode_map);
 252         }
 253         ext2fs_free_mem(&buf);
 254         return retval;
 255 }
 256
 257 errcode_t ext2fs_read_inode_bitmap (ext2_filsys fs)
 258 {
 259         return read_bitmaps(fs, 1, 0);
 260 }
 261
 262 errcode_t ext2fs_read_block_bitmap(ext2_filsys fs)
 263 {
 264         return read_bitmaps(fs, 0, 1);
 265 }
 266
 267 errcode_t ext2fs_read_bitmaps(ext2_filsys fs)
 268 {
 269         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 270
 271         if (fs->inode_map && fs->block_map)
 272                 return 0;
 273
 274         return read_bitmaps(fs, !fs->inode_map, !fs->block_map);
 275 }
 276
 277 errcode_t ext2fs_write_bitmaps(ext2_filsys fs)
 278 {
 279         errcode_t       retval;
 280
 281         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 282
 283         if (fs->block_map && ext2fs_test_bb_dirty(fs)) {
 284                 retval = ext2fs_write_block_bitmap(fs);
 285                 if (retval)
 286                         return retval;
 287         }
 288         if (fs->inode_map && ext2fs_test_ib_dirty(fs)) {
 289                 retval = ext2fs_write_inode_bitmap(fs);
 290                 if (retval)
 291                         return retval;
 292         }
 293         return 0;
 294 }