lib/ext2fs/fileio.c

   1 /*
   2  * fileio.c --- Simple file I/O routines
   3  *
   4  * Copyright (C) 1997 Theodore Ts'o.
   5  *
   6  * %Begin-Header%
   7  * This file may be redistributed under the terms of the GNU Library
   8  * General Public License, version 2.
   9  * %End-Header%
  10  */
  11
  12 #include "config.h"
  13 #include <stdio.h>
  14 #include <string.h>
  15 #if HAVE_UNISTD_H
  16 #include <unistd.h>
  17 #endif
  18
  19 #include "ext2_fs.h"
  20 #include "ext2fs.h"
  21 #include "ext2fsP.h"
  22
  23 struct ext2_file {
  24         errcode_t               magic;
  25         ext2_filsys             fs;
  26         ext2_ino_t              ino;
  27         struct ext2_inode       inode;
  28         int                     flags;
  29         __u64                   pos;
  30         blk64_t                 blockno;
  31         blk64_t                 physblock;
  32         char                    *buf;
  33 };
  34
  35 #define BMAP_BUFFER (file->buf + fs->blocksize)
  36
  37 errcode_t ext2fs_file_open2(ext2_filsys fs, ext2_ino_t ino,
  38                             struct ext2_inode *inode,
  39                             int flags, ext2_file_t *ret)
  40 {
  41         ext2_file_t     file;
  42         errcode_t       retval;
  43
  44         /*
  45          * Don't let caller create or open a file for writing if the
  46          * filesystem is read-only.
  47          */
  48         if ((flags & (EXT2_FILE_WRITE | EXT2_FILE_CREATE)) &&
  49             !(fs->flags & EXT2_FLAG_RW))
  50                 return EXT2_ET_RO_FILSYS;
  51
  52         retval = ext2fs_get_mem(sizeof(struct ext2_file), &file);
  53         if (retval)
  54                 return retval;
  55
  56         memset(file, 0, sizeof(struct ext2_file));
  57         file->magic = EXT2_ET_MAGIC_EXT2_FILE;
  58         file->fs = fs;
  59         file->ino = ino;
  60         file->flags = flags & EXT2_FILE_MASK;
  61
  62         if (inode) {
  63                 memcpy(&file->inode, inode, sizeof(struct ext2_inode));
  64         } else {
  65                 retval = ext2fs_read_inode(fs, ino, &file->inode);
  66                 if (retval)
  67                         goto fail;
  68         }
  69
  70         retval = ext2fs_get_array(3, fs->blocksize, &file->buf);
  71         if (retval)
  72                 goto fail;
  73
  74         *ret = file;
  75         return 0;
  76
  77 fail:
  78         if (file->buf)
  79                 ext2fs_free_mem(&file->buf);
  80         ext2fs_free_mem(&file);
  81         return retval;
  82 }
  83
  84 errcode_t ext2fs_file_open(ext2_filsys fs, ext2_ino_t ino,
  85                            int flags, ext2_file_t *ret)
  86 {
  87         return ext2fs_file_open2(fs, ino, NULL, flags, ret);
  88 }
  89
  90 /*
  91  * This function returns the filesystem handle of a file from the structure
  92  */
  93 ext2_filsys ext2fs_file_get_fs(ext2_file_t file)
  94 {
  95         if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
  96                 return 0;
  97         return file->fs;
  98 }
  99
 100 /*
 101  * This function returns the pointer to the inode of a file from the structure
 102  */
 103 struct ext2_inode *ext2fs_file_get_inode(ext2_file_t file)
 104 {
 105         if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
 106                 return NULL;
 107         return &file->inode;
 108 }
 109
 110 /* This function returns the inode number from the structure */
 111 ext2_ino_t ext2fs_file_get_inode_num(ext2_file_t file)
 112 {
 113         if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
 114                 return 0;
 115         return file->ino;
 116 }
 117
 118 /*
 119  * This function flushes the dirty block buffer out to disk if
 120  * necessary.
 121  */
 122 errcode_t ext2fs_file_flush(ext2_file_t file)
 123 {
 124         errcode_t       retval;
 125         ext2_filsys fs;
 126         int             ret_flags;
 127         blk64_t         dontcare;
 128
 129         EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
 130         fs = file->fs;
 131
 132         if (!(file->flags & EXT2_FILE_BUF_VALID) ||
 133             !(file->flags & EXT2_FILE_BUF_DIRTY))
 134                 return 0;
 135
 136         /* Is this an uninit block? */
 137         if (file->physblock && file->inode.i_flags & EXT4_EXTENTS_FL) {
 138                 retval = ext2fs_bmap2(fs, file->ino, &file->inode, BMAP_BUFFER,
 139                                       0, file->blockno, &ret_flags, &dontcare);
 140                 if (retval)
 141                         return retval;
 142                 if (ret_flags & BMAP_RET_UNINIT) {
 143                         retval = ext2fs_bmap2(fs, file->ino, &file->inode,
 144                                               BMAP_BUFFER, BMAP_SET,
 145                                               file->blockno, 0,
 146                                               &file->physblock);
 147                         if (retval)
 148                                 return retval;
 149                 }
 150         }
 151
 152         /*
 153          * OK, the physical block hasn't been allocated yet.
 154          * Allocate it.
 155          */
 156         if (!file->physblock) {
 157                 retval = ext2fs_bmap2(fs, file->ino, &file->inode,
 158                                      BMAP_BUFFER, file->ino ? BMAP_ALLOC : 0,
 159                                      file->blockno, 0, &file->physblock);
 160                 if (retval)
 161                         return retval;
 162         }
 163
 164         retval = io_channel_write_blk64(fs->io, file->physblock, 1, file->buf);
 165         if (retval)
 166                 return retval;
 167
 168         file->flags &= ~EXT2_FILE_BUF_DIRTY;
 169
 170         return retval;
 171 }
 172
 173 /*
 174  * This function synchronizes the file's block buffer and the current
 175  * file position, possibly invalidating block buffer if necessary
 176  */
 177 static errcode_t sync_buffer_position(ext2_file_t file)
 178 {
 179         blk64_t b;
 180         errcode_t       retval;
 181
 182         b = file->pos / file->fs->blocksize;
 183         if (b != file->blockno) {
 184                 retval = ext2fs_file_flush(file);
 185                 if (retval)
 186                         return retval;
 187                 file->flags &= ~EXT2_FILE_BUF_VALID;
 188         }
 189         file->blockno = b;
 190         return 0;
 191 }
 192
 193 /*
 194  * This function loads the file's block buffer with valid data from
 195  * the disk as necessary.
 196  *
 197  * If dontfill is true, then skip initializing the buffer since we're
 198  * going to be replacing its entire contents anyway.  If set, then the
 199  * function basically only sets file->physblock and EXT2_FILE_BUF_VALID
 200  */
 201 #define DONTFILL 1
 202 static errcode_t load_buffer(ext2_file_t file, int dontfill)
 203 {
 204         ext2_filsys     fs = file->fs;
 205         errcode_t       retval;
 206         int             ret_flags;
 207
 208         if (!(file->flags & EXT2_FILE_BUF_VALID)) {
 209                 retval = ext2fs_bmap2(fs, file->ino, &file->inode,
 210                                      BMAP_BUFFER, 0, file->blockno, &ret_flags,
 211                                      &file->physblock);
 212                 if (retval)
 213                         return retval;
 214                 if (!dontfill) {
 215                         if (file->physblock &&
 216                             !(ret_flags & BMAP_RET_UNINIT)) {
 217                                 retval = io_channel_read_blk64(fs->io,
 218                                                                file->physblock,
 219                                                                1, file->buf);
 220                                 if (retval)
 221                                         return retval;
 222                         } else
 223                                 memset(file->buf, 0, fs->blocksize);
 224                 }
 225                 file->flags |= EXT2_FILE_BUF_VALID;
 226         }
 227         return 0;
 228 }
 229
 230
 231 errcode_t ext2fs_file_close(ext2_file_t file)
 232 {
 233         errcode_t       retval;
 234
 235         EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
 236
 237         retval = ext2fs_file_flush(file);
 238
 239         if (file->buf)
 240                 ext2fs_free_mem(&file->buf);
 241         ext2fs_free_mem(&file);
 242
 243         return retval;
 244 }
 245
 246
 247 static errcode_t
 248 ext2fs_file_read_inline_data(ext2_file_t file, void *buf,
 249                              unsigned int wanted, unsigned int *got)
 250 {
 251         ext2_filsys fs;
 252         errcode_t retval;
 253         unsigned int count = 0;
 254         size_t size;
 255
 256         fs = file->fs;
 257         retval = ext2fs_inline_data_get(fs, file->ino, &file->inode,
 258                                         file->buf, &size);
 259         if (retval)
 260                 return retval;
 261
 262         if (file->pos >= size)
 263                 goto out;
 264
 265         count = size - file->pos;
 266         if (count > wanted)
 267                 count = wanted;
 268         memcpy(buf, file->buf + file->pos, count);
 269         file->pos += count;
 270         buf = (char *) buf + count;
 271
 272 out:
 273         if (got)
 274                 *got = count;
 275         return retval;
 276 }
 277
 278
 279 errcode_t ext2fs_file_read(ext2_file_t file, void *buf,
 280                            unsigned int wanted, unsigned int *got)
 281 {
 282         ext2_filsys     fs;
 283         errcode_t       retval = 0;
 284         unsigned int    start, c, count = 0;
 285         __u64           left;
 286         char            *ptr = (char *) buf;
 287
 288         EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
 289         fs = file->fs;
 290
 291         /* If an inode has inline data, things get complicated. */
 292         if (file->inode.i_flags & EXT4_INLINE_DATA_FL)
 293                 return ext2fs_file_read_inline_data(file, buf, wanted, got);
 294
 295         while ((file->pos < EXT2_I_SIZE(&file->inode)) && (wanted > 0)) {
 296                 retval = sync_buffer_position(file);
 297                 if (retval)
 298                         goto fail;
 299                 retval = load_buffer(file, 0);
 300                 if (retval)
 301                         goto fail;
 302
 303                 start = file->pos % fs->blocksize;
 304                 c = fs->blocksize - start;
 305                 if (c > wanted)
 306                         c = wanted;
 307                 left = EXT2_I_SIZE(&file->inode) - file->pos ;
 308                 if (c > left)
 309                         c = left;
 310
 311                 memcpy(ptr, file->buf+start, c);
 312                 file->pos += c;
 313                 ptr += c;
 314                 count += c;
 315                 wanted -= c;
 316         }
 317
 318 fail:
 319         if (got)
 320                 *got = count;
 321         return retval;
 322 }
 323
 324
 325 static errcode_t
 326 ext2fs_file_write_inline_data(ext2_file_t file, const void *buf,
 327                               unsigned int nbytes, unsigned int *written)
 328 {
 329         ext2_filsys fs;
 330         errcode_t retval;
 331         unsigned int count = 0;
 332         size_t size;
 333
 334         fs = file->fs;
 335         retval = ext2fs_inline_data_get(fs, file->ino, &file->inode,
 336                                         file->buf, &size);
 337         if (retval)
 338                 return retval;
 339
 340         if (file->pos < size) {
 341                 count = nbytes - file->pos;
 342                 memcpy(file->buf + file->pos, buf, count);
 343
 344                 retval = ext2fs_inline_data_set(fs, file->ino, &file->inode,
 345                                                 file->buf, count);
 346                 if (retval == EXT2_ET_INLINE_DATA_NO_SPACE)
 347                         goto expand;
 348                 if (retval)
 349                         return retval;
 350
 351                 file->pos += count;
 352
 353                 /* Update inode size */
 354                 if (count != 0 && EXT2_I_SIZE(&file->inode) < file->pos) {
 355                         errcode_t       rc;
 356
 357                         rc = ext2fs_file_set_size2(file, file->pos);
 358                         if (retval == 0)
 359                                 retval = rc;
 360                 }
 361
 362                 if (written)
 363                         *written = count;
 364                 return 0;
 365         }
 366
 367 expand:
 368         retval = ext2fs_inline_data_expand(fs, file->ino);
 369         if (retval)
 370                 return retval;
 371         /*
 372          * reload inode and return no space error
 373          *
 374          * XXX: file->inode could be copied from the outside
 375          * in ext2fs_file_open2().  We have no way to modify
 376          * the outside inode.
 377          */
 378         retval = ext2fs_read_inode(fs, file->ino, &file->inode);
 379         if (retval)
 380                 return retval;
 381         return EXT2_ET_INLINE_DATA_NO_SPACE;
 382 }
 383
 384
 385 errcode_t ext2fs_file_write(ext2_file_t file, const void *buf,
 386                             unsigned int nbytes, unsigned int *written)
 387 {
 388         ext2_filsys     fs;
 389         errcode_t       retval = 0;
 390         unsigned int    start, c, count = 0;
 391         const char      *ptr = (const char *) buf;
 392
 393         EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
 394         fs = file->fs;
 395
 396         if (!(file->flags & EXT2_FILE_WRITE))
 397                 return EXT2_ET_FILE_RO;
 398
 399         /* If an inode has inline data, things get complicated. */
 400         if (file->inode.i_flags & EXT4_INLINE_DATA_FL) {
 401                 retval = ext2fs_file_write_inline_data(file, buf, nbytes,
 402                                                        written);
 403                 if (retval != EXT2_ET_INLINE_DATA_NO_SPACE)
 404                         return retval;
 405                 /* fall through to read data from the block */
 406                 retval = 0;
 407         }
 408
 409         while (nbytes > 0) {
 410                 retval = sync_buffer_position(file);
 411                 if (retval)
 412                         goto fail;
 413
 414                 start = file->pos % fs->blocksize;
 415                 c = fs->blocksize - start;
 416                 if (c > nbytes)
 417                         c = nbytes;
 418
 419                 /*
 420                  * We only need to do a read-modify-update cycle if
 421                  * we're doing a partial write.
 422                  */
 423                 retval = load_buffer(file, (c == fs->blocksize));
 424                 if (retval)
 425                         goto fail;
 426
 427                 /*
 428                  * OK, the physical block hasn't been allocated yet.
 429                  * Allocate it.
 430                  */
 431                 if (!file->physblock) {
 432                         retval = ext2fs_bmap2(fs, file->ino, &file->inode,
 433                                               BMAP_BUFFER,
 434                                               file->ino ? BMAP_ALLOC : 0,
 435                                               file->blockno, 0,
 436                                               &file->physblock);
 437                         if (retval)
 438                                 goto fail;
 439                 }
 440
 441                 file->flags |= EXT2_FILE_BUF_DIRTY;
 442                 memcpy(file->buf+start, ptr, c);
 443                 file->pos += c;
 444                 ptr += c;
 445                 count += c;
 446                 nbytes -= c;
 447         }
 448
 449 fail:
 450         /* Update inode size */
 451         if (count != 0 && EXT2_I_SIZE(&file->inode) < file->pos) {
 452                 errcode_t       rc;
 453
 454                 rc = ext2fs_file_set_size2(file, file->pos);
 455                 if (retval == 0)
 456                         retval = rc;
 457         }
 458
 459         if (written)
 460                 *written = count;
 461         return retval;
 462 }
 463
 464 errcode_t ext2fs_file_llseek(ext2_file_t file, __u64 offset,
 465                             int whence, __u64 *ret_pos)
 466 {
 467         EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
 468
 469         if (whence == EXT2_SEEK_SET)
 470                 file->pos = offset;
 471         else if (whence == EXT2_SEEK_CUR)
 472                 file->pos += offset;
 473         else if (whence == EXT2_SEEK_END)
 474                 file->pos = EXT2_I_SIZE(&file->inode) + offset;
 475         else
 476                 return EXT2_ET_INVALID_ARGUMENT;
 477
 478         if (ret_pos)
 479                 *ret_pos = file->pos;
 480
 481         return 0;
 482 }
 483
 484 errcode_t ext2fs_file_lseek(ext2_file_t file, ext2_off_t offset,
 485                             int whence, ext2_off_t *ret_pos)
 486 {
 487         __u64           loffset, ret_loffset = 0;
 488         errcode_t       retval;
 489
 490         loffset = offset;
 491         retval = ext2fs_file_llseek(file, loffset, whence, &ret_loffset);
 492         if (ret_pos)
 493                 *ret_pos = (ext2_off_t) ret_loffset;
 494         return retval;
 495 }
 496
 497
 498 /*
 499  * This function returns the size of the file, according to the inode
 500  */
 501 errcode_t ext2fs_file_get_lsize(ext2_file_t file, __u64 *ret_size)
 502 {
 503         if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
 504                 return EXT2_ET_MAGIC_EXT2_FILE;
 505         *ret_size = EXT2_I_SIZE(&file->inode);
 506         return 0;
 507 }
 508
 509 /*
 510  * This function returns the size of the file, according to the inode
 511  */
 512 ext2_off_t ext2fs_file_get_size(ext2_file_t file)
 513 {
 514         __u64   size;
 515
 516         if (ext2fs_file_get_lsize(file, &size))
 517                 return 0;
 518         if ((size >> 32) != 0)
 519                 return 0;
 520         return size;
 521 }
 522
 523 /* Zero the parts of the last block that are past EOF. */
 524 static errcode_t ext2fs_file_zero_past_offset(ext2_file_t file,
 525                                               ext2_off64_t offset)
 526 {
 527         ext2_filsys fs = file->fs;
 528         char *b = NULL;
 529         ext2_off64_t off = offset % fs->blocksize;
 530         blk64_t blk;
 531         int ret_flags;
 532         errcode_t retval;
 533
 534         if (off == 0)
 535                 return 0;
 536
 537         retval = sync_buffer_position(file);
 538         if (retval)
 539                 return retval;
 540
 541         /* Is there an initialized block at the end? */
 542         retval = ext2fs_bmap2(fs, file->ino, NULL, NULL, 0,
 543                               offset / fs->blocksize, &ret_flags, &blk);
 544         if (retval)
 545                 return retval;
 546         if ((blk == 0) || (ret_flags & BMAP_RET_UNINIT))
 547                 return 0;
 548
 549         /* Zero to the end of the block */
 550         retval = ext2fs_get_mem(fs->blocksize, &b);
 551         if (retval)
 552                 return retval;
 553
 554         /* Read/zero/write block */
 555         retval = io_channel_read_blk64(fs->io, blk, 1, b);
 556         if (retval)
 557                 goto out;
 558
 559         memset(b + off, 0, fs->blocksize - off);
 560
 561         retval = io_channel_write_blk64(fs->io, blk, 1, b);
 562         if (retval)
 563                 goto out;
 564
 565 out:
 566         ext2fs_free_mem(&b);
 567         return retval;
 568 }
 569
 570 /*
 571  * This function sets the size of the file, truncating it if necessary
 572  *
 573  */
 574 errcode_t ext2fs_file_set_size2(ext2_file_t file, ext2_off64_t size)
 575 {
 576         ext2_off64_t    old_size;
 577         errcode_t       retval;
 578         blk64_t         old_truncate, truncate_block;
 579
 580         EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
 581
 582         if (size && ext2fs_file_block_offset_too_big(file->fs, &file->inode,
 583                                         (size - 1) / file->fs->blocksize))
 584                 return EXT2_ET_FILE_TOO_BIG;
 585         truncate_block = ((size + file->fs->blocksize - 1) >>
 586                           EXT2_BLOCK_SIZE_BITS(file->fs->super));
 587         old_size = EXT2_I_SIZE(&file->inode);
 588         old_truncate = ((old_size + file->fs->blocksize - 1) >>
 589                       EXT2_BLOCK_SIZE_BITS(file->fs->super));
 590
 591         retval = ext2fs_inode_size_set(file->fs, &file->inode, size);
 592         if (retval)
 593                 return retval;
 594
 595         if (file->ino) {
 596                 retval = ext2fs_write_inode(file->fs, file->ino, &file->inode);
 597                 if (retval)
 598                         return retval;
 599         }
 600
 601         retval = ext2fs_file_zero_past_offset(file, size);
 602         if (retval)
 603                 return retval;
 604
 605         if (truncate_block >= old_truncate)
 606                 return 0;
 607
 608         return ext2fs_punch(file->fs, file->ino, &file->inode, 0,
 609                             truncate_block, ~0ULL);
 610 }
 611
 612 errcode_t ext2fs_file_set_size(ext2_file_t file, ext2_off_t size)
 613 {
 614         return ext2fs_file_set_size2(file, size);
 615 }