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 <stdio.h> 13 #include <string.h> 14 #if HAVE_UNISTD_H 15 #include <unistd.h> 16 #endif 17 18 #include "ext2_fs.h" 19 #include "ext2fs.h" 20 #include "ext2fsP.h" 21 22 struct ext2_file { 23 errcode_t magic; 24 ext2_filsys fs; 25 ext2_ino_t ino; 26 struct ext2_inode inode; 27 int flags; 28 __u64 pos; 29 blk64_t blockno; 30 blk64_t physblock; 31 char *buf; 32 }; 33 34 #define BMAP_BUFFER (file->buf + fs->blocksize) 35 36 errcode_t ext2fs_file_open2(ext2_filsys fs, ext2_ino_t ino, 37 struct ext2_inode *inode, 38 int flags, ext2_file_t *ret) 39 { 40 ext2_file_t file; 41 errcode_t retval; 42 43 /* 44 * Don't let caller create or open a file for writing if the 45 * filesystem is read-only. 46 */ 47 if ((flags & (EXT2_FILE_WRITE | EXT2_FILE_CREATE)) && 48 !(fs->flags & EXT2_FLAG_RW)) 49 return EXT2_ET_RO_FILSYS; 50 51 retval = ext2fs_get_mem(sizeof(struct ext2_file), &file); 52 if (retval) 53 return retval; 54 55 memset(file, 0, sizeof(struct ext2_file)); 56 file->magic = EXT2_ET_MAGIC_EXT2_FILE; 57 file->fs = fs; 58 file->ino = ino; 59 file->flags = flags & EXT2_FILE_MASK; 60 61 if (inode) { 62 memcpy(&file->inode, inode, sizeof(struct ext2_inode)); 63 } else { 64 retval = ext2fs_read_inode(fs, ino, &file->inode); 65 if (retval) 66 goto fail; 67 } 68 69 retval = ext2fs_get_array(3, fs->blocksize, &file->buf); 70 if (retval) 71 goto fail; 72 73 *ret = file; 74 return 0; 75 76 fail: 77 if (file->buf) 78 ext2fs_free_mem(&file->buf); 79 ext2fs_free_mem(&file); 80 return retval; 81 } 82 83 errcode_t ext2fs_file_open(ext2_filsys fs, ext2_ino_t ino, 84 int flags, ext2_file_t *ret) 85 { 86 return ext2fs_file_open2(fs, ino, NULL, flags, ret); 87 } 88 89 /* 90 * This function returns the filesystem handle of a file from the structure 91 */ 92 ext2_filsys ext2fs_file_get_fs(ext2_file_t file) 93 { 94 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE) 95 return 0; 96 return file->fs; 97 } 98 99 /* 100 * This function returns the pointer to the inode of a file from the structure 101 */ 102 struct ext2_inode *ext2fs_file_get_inode(ext2_file_t file) 103 { 104 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE) 105 return NULL; 106 return &file->inode; 107 } 108 109 /* This function returns the inode number from the structure */ 110 ext2_ino_t ext2fs_file_get_inode_num(ext2_file_t file) 111 { 112 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE) 113 return 0; 114 return file->ino; 115 } 116 117 /* 118 * This function flushes the dirty block buffer out to disk if 119 * necessary. 120 */ 121 errcode_t ext2fs_file_flush(ext2_file_t file) 122 { 123 errcode_t retval; 124 ext2_filsys fs; 125 126 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE); 127 fs = file->fs; 128 129 if (!(file->flags & EXT2_FILE_BUF_VALID) || 130 !(file->flags & EXT2_FILE_BUF_DIRTY)) 131 return 0; 132 133 /* 134 * OK, the physical block hasn't been allocated yet. 135 * Allocate it. 136 */ 137 if (!file->physblock) { 138 retval = ext2fs_bmap2(fs, file->ino, &file->inode, 139 BMAP_BUFFER, file->ino ? BMAP_ALLOC : 0, 140 file->blockno, 0, &file->physblock); 141 if (retval) 142 return retval; 143 } 144 145 retval = io_channel_write_blk64(fs->io, file->physblock, 1, file->buf); 146 if (retval) 147 return retval; 148 149 file->flags &= ~EXT2_FILE_BUF_DIRTY; 150 151 return retval; 152 } 153 154 /* 155 * This function synchronizes the file's block buffer and the current 156 * file position, possibly invalidating block buffer if necessary 157 */ 158 static errcode_t sync_buffer_position(ext2_file_t file) 159 { 160 blk64_t b; 161 errcode_t retval; 162 163 b = file->pos / file->fs->blocksize; 164 if (b != file->blockno) { 165 retval = ext2fs_file_flush(file); 166 if (retval) 167 return retval; 168 file->flags &= ~EXT2_FILE_BUF_VALID; 169 } 170 file->blockno = b; 171 return 0; 172 } 173 174 /* 175 * This function loads the file's block buffer with valid data from 176 * the disk as necessary. 177 * 178 * If dontfill is true, then skip initializing the buffer since we're 179 * going to be replacing its entire contents anyway. If set, then the 180 * function basically only sets file->physblock and EXT2_FILE_BUF_VALID 181 */ 182 #define DONTFILL 1 183 static errcode_t load_buffer(ext2_file_t file, int dontfill) 184 { 185 ext2_filsys fs = file->fs; 186 errcode_t retval; 187 188 if (!(file->flags & EXT2_FILE_BUF_VALID)) { 189 retval = ext2fs_bmap2(fs, file->ino, &file->inode, 190 BMAP_BUFFER, 0, file->blockno, 0, 191 &file->physblock); 192 if (retval) 193 return retval; 194 if (!dontfill) { 195 if (file->physblock) { 196 retval = io_channel_read_blk64(fs->io, 197 file->physblock, 198 1, file->buf); 199 if (retval) 200 return retval; 201 } else 202 memset(file->buf, 0, fs->blocksize); 203 } 204 file->flags |= EXT2_FILE_BUF_VALID; 205 } 206 return 0; 207 } 208 209 210 errcode_t ext2fs_file_close(ext2_file_t file) 211 { 212 errcode_t retval; 213 214 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE); 215 216 retval = ext2fs_file_flush(file); 217 218 if (file->buf) 219 ext2fs_free_mem(&file->buf); 220 ext2fs_free_mem(&file); 221 222 return retval; 223 } 224 225 226 errcode_t ext2fs_file_read(ext2_file_t file, void *buf, 227 unsigned int wanted, unsigned int *got) 228 { 229 ext2_filsys fs; 230 errcode_t retval = 0; 231 unsigned int start, c, count = 0; 232 __u64 left; 233 char *ptr = (char *) buf; 234 235 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE); 236 fs = file->fs; 237 238 while ((file->pos < EXT2_I_SIZE(&file->inode)) && (wanted > 0)) { 239 retval = sync_buffer_position(file); 240 if (retval) 241 goto fail; 242 retval = load_buffer(file, 0); 243 if (retval) 244 goto fail; 245 246 start = file->pos % fs->blocksize; 247 c = fs->blocksize - start; 248 if (c > wanted) 249 c = wanted; 250 left = EXT2_I_SIZE(&file->inode) - file->pos ; 251 if (c > left) 252 c = left; 253 254 memcpy(ptr, file->buf+start, c); 255 file->pos += c; 256 ptr += c; 257 count += c; 258 wanted -= c; 259 } 260 261 fail: 262 if (got) 263 *got = count; 264 return retval; 265 } 266 267 268 errcode_t ext2fs_file_write(ext2_file_t file, const void *buf, 269 unsigned int nbytes, unsigned int *written) 270 { 271 ext2_filsys fs; 272 errcode_t retval = 0; 273 unsigned int start, c, count = 0; 274 const char *ptr = (const char *) buf; 275 276 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE); 277 fs = file->fs; 278 279 if (!(file->flags & EXT2_FILE_WRITE)) 280 return EXT2_ET_FILE_RO; 281 282 while (nbytes > 0) { 283 retval = sync_buffer_position(file); 284 if (retval) 285 goto fail; 286 287 start = file->pos % fs->blocksize; 288 c = fs->blocksize - start; 289 if (c > nbytes) 290 c = nbytes; 291 292 /* 293 * We only need to do a read-modify-update cycle if 294 * we're doing a partial write. 295 */ 296 retval = load_buffer(file, (c == fs->blocksize)); 297 if (retval) 298 goto fail; 299 300 /* 301 * OK, the physical block hasn't been allocated yet. 302 * Allocate it. 303 */ 304 if (!file->physblock) { 305 retval = ext2fs_bmap2(fs, file->ino, &file->inode, 306 BMAP_BUFFER, 307 file->ino ? BMAP_ALLOC : 0, 308 file->blockno, 0, 309 &file->physblock); 310 if (retval) 311 goto fail; 312 } 313 314 file->flags |= EXT2_FILE_BUF_DIRTY; 315 memcpy(file->buf+start, ptr, c); 316 file->pos += c; 317 ptr += c; 318 count += c; 319 nbytes -= c; 320 } 321 322 fail: 323 /* Update inode size */ 324 if (count != 0 && EXT2_I_SIZE(&file->inode) < file->pos) { 325 errcode_t rc; 326 327 rc = ext2fs_file_set_size2(file, file->pos); 328 if (retval == 0) 329 retval = rc; 330 } 331 332 if (written) 333 *written = count; 334 return retval; 335 } 336 337 errcode_t ext2fs_file_llseek(ext2_file_t file, __u64 offset, 338 int whence, __u64 *ret_pos) 339 { 340 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE); 341 342 if (whence == EXT2_SEEK_SET) 343 file->pos = offset; 344 else if (whence == EXT2_SEEK_CUR) 345 file->pos += offset; 346 else if (whence == EXT2_SEEK_END) 347 file->pos = EXT2_I_SIZE(&file->inode) + offset; 348 else 349 return EXT2_ET_INVALID_ARGUMENT; 350 351 if (ret_pos) 352 *ret_pos = file->pos; 353 354 return 0; 355 } 356 357 errcode_t ext2fs_file_lseek(ext2_file_t file, ext2_off_t offset, 358 int whence, ext2_off_t *ret_pos) 359 { 360 __u64 loffset, ret_loffset; 361 errcode_t retval; 362 363 loffset = offset; 364 retval = ext2fs_file_llseek(file, loffset, whence, &ret_loffset); 365 if (ret_pos) 366 *ret_pos = (ext2_off_t) ret_loffset; 367 return retval; 368 } 369 370 371 /* 372 * This function returns the size of the file, according to the inode 373 */ 374 errcode_t ext2fs_file_get_lsize(ext2_file_t file, __u64 *ret_size) 375 { 376 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE) 377 return EXT2_ET_MAGIC_EXT2_FILE; 378 *ret_size = EXT2_I_SIZE(&file->inode); 379 return 0; 380 } 381 382 /* 383 * This function returns the size of the file, according to the inode 384 */ 385 ext2_off_t ext2fs_file_get_size(ext2_file_t file) 386 { 387 __u64 size; 388 389 if (ext2fs_file_get_lsize(file, &size)) 390 return 0; 391 if ((size >> 32) != 0) 392 return 0; 393 return size; 394 } 395 396 /* Zero the parts of the last block that are past EOF. */ 397 static errcode_t ext2fs_file_zero_past_offset(ext2_file_t file, 398 ext2_off64_t offset) 399 { 400 ext2_filsys fs = file->fs; 401 char *b = NULL; 402 ext2_off64_t off = offset % fs->blocksize; 403 blk64_t blk; 404 int ret_flags; 405 errcode_t retval; 406 407 if (off == 0) 408 return 0; 409 410 retval = sync_buffer_position(file); 411 if (retval) 412 return retval; 413 414 /* Is there an initialized block at the end? */ 415 retval = ext2fs_bmap2(fs, file->ino, NULL, NULL, 0, 416 offset / fs->blocksize, &ret_flags, &blk); 417 if (retval) 418 return retval; 419 if ((blk == 0) || (ret_flags & BMAP_RET_UNINIT)) 420 return 0; 421 422 /* Zero to the end of the block */ 423 retval = ext2fs_get_mem(fs->blocksize, &b); 424 if (retval) 425 return retval; 426 427 /* Read/zero/write block */ 428 retval = io_channel_read_blk64(fs->io, blk, 1, b); 429 if (retval) 430 goto out; 431 432 memset(b + off, 0, fs->blocksize - off); 433 434 retval = io_channel_write_blk64(fs->io, blk, 1, b); 435 if (retval) 436 goto out; 437 438 out: 439 ext2fs_free_mem(&b); 440 return retval; 441 } 442 443 /* 444 * This function sets the size of the file, truncating it if necessary 445 * 446 */ 447 errcode_t ext2fs_file_set_size2(ext2_file_t file, ext2_off64_t size) 448 { 449 ext2_off64_t old_size; 450 errcode_t retval; 451 blk64_t old_truncate, truncate_block; 452 453 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE); 454 455 if (size && ext2fs_file_block_offset_too_big(file->fs, &file->inode, 456 (size - 1) / file->fs->blocksize)) 457 return EXT2_ET_FILE_TOO_BIG; 458 truncate_block = ((size + file->fs->blocksize - 1) >> 459 EXT2_BLOCK_SIZE_BITS(file->fs->super)); 460 old_size = EXT2_I_SIZE(&file->inode); 461 old_truncate = ((old_size + file->fs->blocksize - 1) >> 462 EXT2_BLOCK_SIZE_BITS(file->fs->super)); 463 464 /* If we're writing a large file, set the large_file flag */ 465 if (LINUX_S_ISREG(file->inode.i_mode) && 466 ext2fs_needs_large_file_feature(EXT2_I_SIZE(&file->inode)) && 467 (!EXT2_HAS_RO_COMPAT_FEATURE(file->fs->super, 468 EXT2_FEATURE_RO_COMPAT_LARGE_FILE) || 469 file->fs->super->s_rev_level == EXT2_GOOD_OLD_REV)) { 470 file->fs->super->s_feature_ro_compat |= 471 EXT2_FEATURE_RO_COMPAT_LARGE_FILE; 472 ext2fs_update_dynamic_rev(file->fs); 473 ext2fs_mark_super_dirty(file->fs); 474 } 475 476 file->inode.i_size = size & 0xffffffff; 477 file->inode.i_size_high = (size >> 32); 478 if (file->ino) { 479 retval = ext2fs_write_inode(file->fs, file->ino, &file->inode); 480 if (retval) 481 return retval; 482 } 483 484 retval = ext2fs_file_zero_past_offset(file, size); 485 if (retval) 486 return retval; 487 488 if (truncate_block >= old_truncate) 489 return 0; 490 491 return ext2fs_punch(file->fs, file->ino, &file->inode, 0, 492 truncate_block, ~0ULL); 493 } 494 495 errcode_t ext2fs_file_set_size(ext2_file_t file, ext2_off_t size) 496 { 497 return ext2fs_file_set_size2(file, size); 498 } 499
