lib/ext2fs/imager.c

   1 /*
   2  * image.c --- writes out the critical parts of the filesystem as a
   3  *      flat file.
   4  *
   5  * Copyright (C) 2000 Theodore Ts'o.
   6  *
   7  * Note: this uses the POSIX IO interfaces, unlike most of the other
   8  * functions in this library.  So sue me.
   9  *
  10  * %Begin-Header%
  11  * This file may be redistributed under the terms of the GNU Library
  12  * General Public License, version 2.
  13  * %End-Header%
  14  */
  15
  16 #include "config.h"
  17 #include <stdio.h>
  18 #include <string.h>
  19 #if HAVE_UNISTD_H
  20 #include <unistd.h>
  21 #endif
  22 #if HAVE_ERRNO_H
  23 #include <errno.h>
  24 #endif
  25 #include <fcntl.h>
  26 #include <time.h>
  27 #if HAVE_SYS_STAT_H
  28 #include <sys/stat.h>
  29 #endif
  30 #if HAVE_SYS_TYPES_H
  31 #include <sys/types.h>
  32 #endif
  33
  34 #include "ext2_fs.h"
  35 #include "ext2fs.h"
  36
  37 #ifndef HAVE_TYPE_SSIZE_T
  38 typedef int ssize_t;
  39 #endif
  40
  41 /*
  42  * This function returns 1 if the specified block is all zeros
  43  */
  44 static int check_zero_block(char *buf, int blocksize)
  45 {
  46         char    *cp = buf;
  47         int     left = blocksize;
  48
  49         while (left > 0) {
  50                 if (*cp++)
  51                         return 0;
  52                 left--;
  53         }
  54         return 1;
  55 }
  56
  57 /*
  58  * Write the inode table out as a single block.
  59  */
  60 #define BUF_BLOCKS      32
  61
  62 errcode_t ext2fs_image_inode_write(ext2_filsys fs, int fd, int flags)
  63 {
  64         unsigned int    group, left, c, d;
  65         char            *buf, *cp;
  66         blk64_t         blk;
  67         ssize_t         actual;
  68         errcode_t       retval;
  69         off_t           r;
  70
  71         buf = malloc(fs->blocksize * BUF_BLOCKS);
  72         if (!buf)
  73                 return ENOMEM;
  74
  75         for (group = 0; group < fs->group_desc_count; group++) {
  76                 blk = ext2fs_inode_table_loc(fs, (unsigned)group);
  77                 if (!blk) {
  78                         retval = EXT2_ET_MISSING_INODE_TABLE;
  79                         goto errout;
  80                 }
  81                 left = fs->inode_blocks_per_group;
  82                 while (left) {
  83                         c = BUF_BLOCKS;
  84                         if (c > left)
  85                                 c = left;
  86                         retval = io_channel_read_blk64(fs->io, blk, c, buf);
  87                         if (retval)
  88                                 goto errout;
  89                         cp = buf;
  90                         while (c) {
  91                                 if (!(flags & IMAGER_FLAG_SPARSEWRITE)) {
  92                                         d = c;
  93                                         goto skip_sparse;
  94                                 }
  95                                 /* Skip zero blocks */
  96                                 if (check_zero_block(cp, fs->blocksize)) {
  97                                         c--;
  98                                         blk++;
  99                                         left--;
 100                                         cp += fs->blocksize;
 101                                         r = ext2fs_llseek(fd, fs->blocksize,
 102                                                           SEEK_CUR);
 103                                         if (r < 0) {
 104                                                 retval = errno;
 105                                                 goto errout;
 106                                         }
 107                                         continue;
 108                                 }
 109                                 /* Find non-zero blocks */
 110                                 for (d=1; d < c; d++) {
 111                                         if (check_zero_block(cp + d*fs->blocksize, fs->blocksize))
 112                                                 break;
 113                                 }
 114                         skip_sparse:
 115                                 actual = write(fd, cp, fs->blocksize * d);
 116                                 if (actual == -1) {
 117                                         retval = errno;
 118                                         goto errout;
 119                                 }
 120                                 if (actual != (ssize_t) (fs->blocksize * d)) {
 121                                         retval = EXT2_ET_SHORT_WRITE;
 122                                         goto errout;
 123                                 }
 124                                 blk += d;
 125                                 left -= d;
 126                                 cp += fs->blocksize * d;
 127                                 c -= d;
 128                         }
 129                 }
 130         }
 131         retval = 0;
 132
 133 errout:
 134         free(buf);
 135         return retval;
 136 }
 137
 138 /*
 139  * Read in the inode table and stuff it into place
 140  */
 141 errcode_t ext2fs_image_inode_read(ext2_filsys fs, int fd,
 142                                   int flags EXT2FS_ATTR((unused)))
 143 {
 144         unsigned int    group, c, left;
 145         char            *buf;
 146         blk64_t         blk;
 147         ssize_t         actual;
 148         errcode_t       retval;
 149
 150         buf = malloc(fs->blocksize * BUF_BLOCKS);
 151         if (!buf)
 152                 return ENOMEM;
 153
 154         for (group = 0; group < fs->group_desc_count; group++) {
 155                 blk = ext2fs_inode_table_loc(fs, (unsigned)group);
 156                 if (!blk) {
 157                         retval = EXT2_ET_MISSING_INODE_TABLE;
 158                         goto errout;
 159                 }
 160                 left = fs->inode_blocks_per_group;
 161                 while (left) {
 162                         c = BUF_BLOCKS;
 163                         if (c > left)
 164                                 c = left;
 165                         actual = read(fd, buf, fs->blocksize * c);
 166                         if (actual == -1) {
 167                                 retval = errno;
 168                                 goto errout;
 169                         }
 170                         if (actual != (ssize_t) (fs->blocksize * c)) {
 171                                 retval = EXT2_ET_SHORT_READ;
 172                                 goto errout;
 173                         }
 174                         retval = io_channel_write_blk64(fs->io, blk, c, buf);
 175                         if (retval)
 176                                 goto errout;
 177
 178                         blk += c;
 179                         left -= c;
 180                 }
 181         }
 182         retval = ext2fs_flush_icache(fs);
 183
 184 errout:
 185         free(buf);
 186         return retval;
 187 }
 188
 189 /*
 190  * Write out superblock and group descriptors
 191  */
 192 errcode_t ext2fs_image_super_write(ext2_filsys fs, int fd,
 193                                    int flags EXT2FS_ATTR((unused)))
 194 {
 195         char            *buf, *cp;
 196         ssize_t         actual;
 197         errcode_t       retval;
 198 #ifdef WORDS_BIGENDIAN
 199         unsigned int    groups_per_block;
 200         struct          ext2_group_desc *gdp;
 201         int             j;
 202 #endif
 203
 204         buf = malloc(fs->blocksize);
 205         if (!buf)
 206                 return ENOMEM;
 207
 208         /*
 209          * Write out the superblock
 210          */
 211         memset(buf, 0, fs->blocksize);
 212 #ifdef WORDS_BIGENDIAN
 213         /*
 214          * We're writing out superblock so let's convert
 215          * it to little endian and then back if needed
 216          */
 217         ext2fs_swap_super(fs->super);
 218         memcpy(buf, fs->super, SUPERBLOCK_SIZE);
 219         ext2fs_swap_super(fs->super);
 220 #else
 221         memcpy(buf, fs->super, SUPERBLOCK_SIZE);
 222 #endif
 223         actual = write(fd, buf, fs->blocksize);
 224         if (actual == -1) {
 225                 retval = errno;
 226                 goto errout;
 227         }
 228         if (actual != (ssize_t) fs->blocksize) {
 229                 retval = EXT2_ET_SHORT_WRITE;
 230                 goto errout;
 231         }
 232
 233         /*
 234          * Now write out the block group descriptors
 235          */
 236
 237         cp = (char *) fs->group_desc;
 238
 239 #ifdef WORDS_BIGENDIAN
 240         /*
 241          * Convert group descriptors to little endian and back
 242          * if needed
 243          */
 244         groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
 245         for (j=0; j < groups_per_block*fs->desc_blocks; j++) {
 246                 gdp = ext2fs_group_desc(fs, fs->group_desc, j);
 247                 if (gdp)
 248                         ext2fs_swap_group_desc2(fs, gdp);
 249         }
 250 #endif
 251
 252         actual = write(fd, cp, fs->blocksize * fs->desc_blocks);
 253
 254
 255 #ifdef WORDS_BIGENDIAN
 256         groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
 257         for (j=0; j < groups_per_block*fs->desc_blocks; j++) {
 258                 gdp = ext2fs_group_desc(fs, fs->group_desc, j);
 259                 if (gdp)
 260                         ext2fs_swap_group_desc2(fs, gdp);
 261         }
 262 #endif
 263
 264         if (actual == -1) {
 265                 retval = errno;
 266                 goto errout;
 267         }
 268         if (actual != (ssize_t) (fs->blocksize * fs->desc_blocks)) {
 269                 retval = EXT2_ET_SHORT_WRITE;
 270                 goto errout;
 271         }
 272
 273         retval = 0;
 274
 275 errout:
 276         free(buf);
 277         return retval;
 278 }
 279
 280 /*
 281  * Read the superblock and group descriptors and overwrite them.
 282  */
 283 errcode_t ext2fs_image_super_read(ext2_filsys fs, int fd,
 284                                   int flags EXT2FS_ATTR((unused)))
 285 {
 286         char            *buf;
 287         ssize_t         actual, size;
 288         errcode_t       retval;
 289
 290         size = fs->blocksize * (fs->group_desc_count + 1);
 291         buf = malloc(size);
 292         if (!buf)
 293                 return ENOMEM;
 294
 295         /*
 296          * Read it all in.
 297          */
 298         actual = read(fd, buf, size);
 299         if (actual == -1) {
 300                 retval = errno;
 301                 goto errout;
 302         }
 303         if (actual != size) {
 304                 retval = EXT2_ET_SHORT_READ;
 305                 goto errout;
 306         }
 307
 308         /*
 309          * Now copy in the superblock and group descriptors
 310          */
 311         memcpy(fs->super, buf, SUPERBLOCK_SIZE);
 312
 313         memcpy(fs->group_desc, buf + fs->blocksize,
 314                fs->blocksize * fs->group_desc_count);
 315
 316         retval = 0;
 317
 318 errout:
 319         free(buf);
 320         return retval;
 321 }
 322
 323 /*
 324  * Write the block/inode bitmaps.
 325  */
 326 errcode_t ext2fs_image_bitmap_write(ext2_filsys fs, int fd, int flags)
 327 {
 328         ext2fs_generic_bitmap   bmap;
 329         errcode_t               retval;
 330         ssize_t                 actual;
 331         size_t                  c;
 332         __u64                   itr, cnt, size, total_size;
 333         char                    buf[1024];
 334
 335         if (flags & IMAGER_FLAG_INODEMAP) {
 336                 if (!fs->inode_map) {
 337                         retval = ext2fs_read_inode_bitmap(fs);
 338                         if (retval)
 339                                 return retval;
 340                 }
 341                 bmap = fs->inode_map;
 342                 itr = 1;
 343                 cnt = EXT2_INODES_PER_GROUP(fs->super) * fs->group_desc_count;
 344                 size = (EXT2_INODES_PER_GROUP(fs->super) / 8);
 345         } else {
 346                 if (!fs->block_map) {
 347                         retval = ext2fs_read_block_bitmap(fs);
 348                         if (retval)
 349                                 return retval;
 350                 }
 351                 bmap = fs->block_map;
 352                 itr = fs->super->s_first_data_block;
 353                 cnt = EXT2_GROUPS_TO_CLUSTERS(fs->super, fs->group_desc_count);
 354                 size = EXT2_CLUSTERS_PER_GROUP(fs->super) / 8;
 355         }
 356         total_size = size * fs->group_desc_count;
 357
 358         while (cnt > 0) {
 359                 size = sizeof(buf);
 360                 if (size > (cnt >> 3))
 361                         size = (cnt >> 3);
 362
 363                 retval = ext2fs_get_generic_bmap_range(bmap, itr,
 364                                                        size << 3, buf);
 365                 if (retval)
 366                         return retval;
 367
 368                 actual = write(fd, buf, size);
 369                 if (actual == -1)
 370                         return errno;
 371                 if (actual != (int) size)
 372                         return EXT2_ET_SHORT_READ;
 373
 374                 itr += size << 3;
 375                 cnt -= size << 3;
 376         }
 377
 378         size = total_size % fs->blocksize;
 379         memset(buf, 0, sizeof(buf));
 380         if (size) {
 381                 size = fs->blocksize - size;
 382                 while (size) {
 383                         c = size;
 384                         if (c > (int) sizeof(buf))
 385                                 c = sizeof(buf);
 386                         actual = write(fd, buf, c);
 387                         if (actual < 0)
 388                                 return errno;
 389                         if ((size_t) actual != c)
 390                                 return EXT2_ET_SHORT_WRITE;
 391                         size -= c;
 392                 }
 393         }
 394         return 0;
 395 }
 396
 397
 398 /*
 399  * Read the block/inode bitmaps.
 400  */
 401 errcode_t ext2fs_image_bitmap_read(ext2_filsys fs, int fd, int flags)
 402 {
 403         ext2fs_generic_bitmap   bmap;
 404         errcode_t               retval;
 405         __u64                   itr, cnt;
 406         char                    buf[1024];
 407         unsigned int            size;
 408         ssize_t                 actual;
 409
 410         if (flags & IMAGER_FLAG_INODEMAP) {
 411                 if (!fs->inode_map) {
 412                         retval = ext2fs_read_inode_bitmap(fs);
 413                         if (retval)
 414                                 return retval;
 415                 }
 416                 bmap = fs->inode_map;
 417                 itr = 1;
 418                 cnt = EXT2_INODES_PER_GROUP(fs->super) * fs->group_desc_count;
 419                 size = (EXT2_INODES_PER_GROUP(fs->super) / 8);
 420         } else {
 421                 if (!fs->block_map) {
 422                         retval = ext2fs_read_block_bitmap(fs);
 423                         if (retval)
 424                                 return retval;
 425                 }
 426                 bmap = fs->block_map;
 427                 itr = fs->super->s_first_data_block;
 428                 cnt = EXT2_GROUPS_TO_BLOCKS(fs->super, fs->group_desc_count);
 429                 size = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
 430         }
 431
 432         while (cnt > 0) {
 433                 size = sizeof(buf);
 434                 if (size > (cnt >> 3))
 435                         size = (cnt >> 3);
 436
 437                 actual = read(fd, buf, size);
 438                 if (actual == -1)
 439                         return errno;
 440                 if (actual != (int) size)
 441                         return EXT2_ET_SHORT_READ;
 442
 443                 retval = ext2fs_set_generic_bmap_range(bmap, itr,
 444                                                        size << 3, buf);
 445                 if (retval)
 446                         return retval;
 447
 448                 itr += size << 3;
 449                 cnt -= size << 3;
 450         }
 451         return 0;
 452 }