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 struct block_entry {
36 blk64_t physblock;
37 unsigned char sha[EXT2FS_SHA512_LENGTH];
38 };
39 typedef struct block_entry *block_entry_t;
40
41 #define BMAP_BUFFER (file->buf + fs->blocksize)
42
ext2fs_file_open2(ext2_filsys fs,ext2_ino_t ino,struct ext2_inode * inode,int flags,ext2_file_t * ret)43 errcode_t ext2fs_file_open2(ext2_filsys fs, ext2_ino_t ino,
44 struct ext2_inode *inode,
45 int flags, ext2_file_t *ret)
46 {
47 ext2_file_t file;
48 errcode_t retval;
49
50 /*
51 * Don't let caller create or open a file for writing if the
52 * filesystem is read-only.
53 */
54 if ((flags & (EXT2_FILE_WRITE | EXT2_FILE_CREATE)) &&
55 !(fs->flags & EXT2_FLAG_RW))
56 return EXT2_ET_RO_FILSYS;
57
58 retval = ext2fs_get_mem(sizeof(struct ext2_file), &file);
59 if (retval)
60 return retval;
61
62 memset(file, 0, sizeof(struct ext2_file));
63 file->magic = EXT2_ET_MAGIC_EXT2_FILE;
64 file->fs = fs;
65 file->ino = ino;
66 file->flags = flags & EXT2_FILE_MASK;
67
68 if (inode) {
69 memcpy(&file->inode, inode, sizeof(struct ext2_inode));
70 } else {
71 retval = ext2fs_read_inode(fs, ino, &file->inode);
72 if (retval)
73 goto fail;
74 }
75
76 retval = ext2fs_get_array(3, fs->blocksize, &file->buf);
77 if (retval)
78 goto fail;
79
80 *ret = file;
81 return 0;
82
83 fail:
84 if (file->buf)
85 ext2fs_free_mem(&file->buf);
86 ext2fs_free_mem(&file);
87 return retval;
88 }
89
ext2fs_file_open(ext2_filsys fs,ext2_ino_t ino,int flags,ext2_file_t * ret)90 errcode_t ext2fs_file_open(ext2_filsys fs, ext2_ino_t ino,
91 int flags, ext2_file_t *ret)
92 {
93 return ext2fs_file_open2(fs, ino, NULL, flags, ret);
94 }
95
96 /*
97 * This function returns the filesystem handle of a file from the structure
98 */
ext2fs_file_get_fs(ext2_file_t file)99 ext2_filsys ext2fs_file_get_fs(ext2_file_t file)
100 {
101 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
102 return 0;
103 return file->fs;
104 }
105
106 /*
107 * This function returns the pointer to the inode of a file from the structure
108 */
ext2fs_file_get_inode(ext2_file_t file)109 struct ext2_inode *ext2fs_file_get_inode(ext2_file_t file)
110 {
111 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
112 return NULL;
113 return &file->inode;
114 }
115
116 /* This function returns the inode number from the structure */
ext2fs_file_get_inode_num(ext2_file_t file)117 ext2_ino_t ext2fs_file_get_inode_num(ext2_file_t file)
118 {
119 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
120 return 0;
121 return file->ino;
122 }
123
124 /*
125 * This function flushes the dirty block buffer out to disk if
126 * necessary.
127 */
ext2fs_file_flush(ext2_file_t file)128 errcode_t ext2fs_file_flush(ext2_file_t file)
129 {
130 errcode_t retval;
131 ext2_filsys fs;
132 int ret_flags;
133 blk64_t dontcare;
134
135 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
136 fs = file->fs;
137
138 if (!(file->flags & EXT2_FILE_BUF_VALID) ||
139 !(file->flags & EXT2_FILE_BUF_DIRTY))
140 return 0;
141
142 /* Is this an uninit block? */
143 if (file->physblock && file->inode.i_flags & EXT4_EXTENTS_FL) {
144 retval = ext2fs_bmap2(fs, file->ino, &file->inode, BMAP_BUFFER,
145 0, file->blockno, &ret_flags, &dontcare);
146 if (retval)
147 return retval;
148 if (ret_flags & BMAP_RET_UNINIT) {
149 retval = ext2fs_bmap2(fs, file->ino, &file->inode,
150 BMAP_BUFFER, BMAP_SET,
151 file->blockno, 0,
152 &file->physblock);
153 if (retval)
154 return retval;
155 }
156 }
157
158 /*
159 * OK, the physical block hasn't been allocated yet.
160 * Allocate it.
161 */
162 if (!file->physblock) {
163 retval = ext2fs_bmap2(fs, file->ino, &file->inode,
164 BMAP_BUFFER, file->ino ? BMAP_ALLOC : 0,
165 file->blockno, 0, &file->physblock);
166 if (retval)
167 return retval;
168 }
169
170 retval = io_channel_write_blk64(fs->io, file->physblock, 1, file->buf);
171 if (retval)
172 return retval;
173
174 file->flags &= ~EXT2_FILE_BUF_DIRTY;
175
176 return retval;
177 }
178
179 /*
180 * This function synchronizes the file's block buffer and the current
181 * file position, possibly invalidating block buffer if necessary
182 */
sync_buffer_position(ext2_file_t file)183 static errcode_t sync_buffer_position(ext2_file_t file)
184 {
185 blk64_t b;
186 errcode_t retval;
187
188 b = file->pos / file->fs->blocksize;
189 if (b != file->blockno) {
190 retval = ext2fs_file_flush(file);
191 if (retval)
192 return retval;
193 file->flags &= ~EXT2_FILE_BUF_VALID;
194 }
195 file->blockno = b;
196 return 0;
197 }
198
199 /*
200 * This function loads the file's block buffer with valid data from
201 * the disk as necessary.
202 *
203 * If dontfill is true, then skip initializing the buffer since we're
204 * going to be replacing its entire contents anyway. If set, then the
205 * function basically only sets file->physblock and EXT2_FILE_BUF_VALID
206 */
207 #define DONTFILL 1
load_buffer(ext2_file_t file,int dontfill)208 static errcode_t load_buffer(ext2_file_t file, int dontfill)
209 {
210 ext2_filsys fs = file->fs;
211 errcode_t retval;
212 int ret_flags;
213
214 if (!(file->flags & EXT2_FILE_BUF_VALID)) {
215 retval = ext2fs_bmap2(fs, file->ino, &file->inode,
216 BMAP_BUFFER, 0, file->blockno, &ret_flags,
217 &file->physblock);
218 if (retval)
219 return retval;
220 if (!dontfill) {
221 if (file->physblock &&
222 !(ret_flags & BMAP_RET_UNINIT)) {
223 retval = io_channel_read_blk64(fs->io,
224 file->physblock,
225 1, file->buf);
226 if (retval)
227 return retval;
228 } else
229 memset(file->buf, 0, fs->blocksize);
230 }
231 file->flags |= EXT2_FILE_BUF_VALID;
232 }
233 return 0;
234 }
235
236
ext2fs_file_close(ext2_file_t file)237 errcode_t ext2fs_file_close(ext2_file_t file)
238 {
239 errcode_t retval;
240
241 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
242
243 retval = ext2fs_file_flush(file);
244
245 if (file->buf)
246 ext2fs_free_mem(&file->buf);
247 ext2fs_free_mem(&file);
248
249 return retval;
250 }
251
252
253 static errcode_t
ext2fs_file_read_inline_data(ext2_file_t file,void * buf,unsigned int wanted,unsigned int * got)254 ext2fs_file_read_inline_data(ext2_file_t file, void *buf,
255 unsigned int wanted, unsigned int *got)
256 {
257 ext2_filsys fs;
258 errcode_t retval;
259 unsigned int count = 0;
260 size_t size;
261
262 fs = file->fs;
263 retval = ext2fs_inline_data_get(fs, file->ino, &file->inode,
264 file->buf, &size);
265 if (retval)
266 return retval;
267
268 if (file->pos >= size)
269 goto out;
270
271 count = size - file->pos;
272 if (count > wanted)
273 count = wanted;
274 memcpy(buf, file->buf + file->pos, count);
275 file->pos += count;
276 buf = (char *) buf + count;
277
278 out:
279 if (got)
280 *got = count;
281 return retval;
282 }
283
284
ext2fs_file_read(ext2_file_t file,void * buf,unsigned int wanted,unsigned int * got)285 errcode_t ext2fs_file_read(ext2_file_t file, void *buf,
286 unsigned int wanted, unsigned int *got)
287 {
288 ext2_filsys fs;
289 errcode_t retval = 0;
290 unsigned int start, c, count = 0;
291 __u64 left;
292 char *ptr = (char *) buf;
293
294 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
295 fs = file->fs;
296
297 /* If an inode has inline data, things get complicated. */
298 if (file->inode.i_flags & EXT4_INLINE_DATA_FL)
299 return ext2fs_file_read_inline_data(file, buf, wanted, got);
300
301 while ((file->pos < EXT2_I_SIZE(&file->inode)) && (wanted > 0)) {
302 retval = sync_buffer_position(file);
303 if (retval)
304 goto fail;
305 retval = load_buffer(file, 0);
306 if (retval)
307 goto fail;
308
309 start = file->pos % fs->blocksize;
310 c = fs->blocksize - start;
311 if (c > wanted)
312 c = wanted;
313 left = EXT2_I_SIZE(&file->inode) - file->pos ;
314 if (c > left)
315 c = left;
316
317 memcpy(ptr, file->buf+start, c);
318 file->pos += c;
319 ptr += c;
320 count += c;
321 wanted -= c;
322 }
323
324 fail:
325 if (got)
326 *got = count;
327 return retval;
328 }
329
330
331 static errcode_t
ext2fs_file_write_inline_data(ext2_file_t file,const void * buf,unsigned int nbytes,unsigned int * written)332 ext2fs_file_write_inline_data(ext2_file_t file, const void *buf,
333 unsigned int nbytes, unsigned int *written)
334 {
335 ext2_filsys fs;
336 errcode_t retval;
337 unsigned int count = 0;
338 size_t size;
339
340 fs = file->fs;
341 retval = ext2fs_inline_data_get(fs, file->ino, &file->inode,
342 file->buf, &size);
343 if (retval)
344 return retval;
345
346 if (file->pos < size) {
347 count = nbytes - file->pos;
348 memcpy(file->buf + file->pos, buf, count);
349
350 retval = ext2fs_inline_data_set(fs, file->ino, &file->inode,
351 file->buf, count);
352 if (retval == EXT2_ET_INLINE_DATA_NO_SPACE)
353 goto expand;
354 if (retval)
355 return retval;
356
357 file->pos += count;
358
359 /* Update inode size */
360 if (count != 0 && EXT2_I_SIZE(&file->inode) < file->pos) {
361 errcode_t rc;
362
363 rc = ext2fs_file_set_size2(file, file->pos);
364 if (retval == 0)
365 retval = rc;
366 }
367
368 if (written)
369 *written = count;
370 return 0;
371 }
372
373 expand:
374 retval = ext2fs_inline_data_expand(fs, file->ino);
375 if (retval)
376 return retval;
377 /*
378 * reload inode and return no space error
379 *
380 * XXX: file->inode could be copied from the outside
381 * in ext2fs_file_open2(). We have no way to modify
382 * the outside inode.
383 */
384 retval = ext2fs_read_inode(fs, file->ino, &file->inode);
385 if (retval)
386 return retval;
387 return EXT2_ET_INLINE_DATA_NO_SPACE;
388 }
389
390
ext2fs_file_write(ext2_file_t file,const void * buf,unsigned int nbytes,unsigned int * written)391 errcode_t ext2fs_file_write(ext2_file_t file, const void *buf,
392 unsigned int nbytes, unsigned int *written)
393 {
394 ext2_filsys fs;
395 errcode_t retval = 0;
396 unsigned int start, c, count = 0;
397 const char *ptr = (const char *) buf;
398 block_entry_t new_block = NULL, old_block = NULL;
399 int bmap_flags = 0;
400
401 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
402 fs = file->fs;
403
404 if (!(file->flags & EXT2_FILE_WRITE))
405 return EXT2_ET_FILE_RO;
406
407 /* If an inode has inline data, things get complicated. */
408 if (file->inode.i_flags & EXT4_INLINE_DATA_FL) {
409 retval = ext2fs_file_write_inline_data(file, buf, nbytes,
410 written);
411 if (retval != EXT2_ET_INLINE_DATA_NO_SPACE)
412 return retval;
413 /* fall through to read data from the block */
414 retval = 0;
415 }
416
417 while (nbytes > 0) {
418 retval = sync_buffer_position(file);
419 if (retval)
420 goto fail;
421
422 start = file->pos % fs->blocksize;
423 c = fs->blocksize - start;
424 if (c > nbytes)
425 c = nbytes;
426
427 /*
428 * We only need to do a read-modify-update cycle if
429 * we're doing a partial write.
430 */
431 retval = load_buffer(file, (c == fs->blocksize));
432 if (retval)
433 goto fail;
434
435 file->flags |= EXT2_FILE_BUF_DIRTY;
436 memcpy(file->buf+start, ptr, c);
437
438 /*
439 * OK, the physical block hasn't been allocated yet.
440 * Allocate it.
441 */
442 if (!file->physblock) {
443 bmap_flags = (file->ino ? BMAP_ALLOC : 0);
444 if (fs->flags & EXT2_FLAG_SHARE_DUP) {
445 new_block = calloc(1, sizeof(*new_block));
446 if (!new_block) {
447 retval = EXT2_ET_NO_MEMORY;
448 goto fail;
449 }
450 ext2fs_sha512((const unsigned char*)file->buf,
451 fs->blocksize, new_block->sha);
452 old_block = ext2fs_hashmap_lookup(
453 fs->block_sha_map,
454 new_block->sha,
455 sizeof(new_block->sha));
456 }
457
458 if (old_block) {
459 file->physblock = old_block->physblock;
460 bmap_flags |= BMAP_SET;
461 free(new_block);
462 new_block = NULL;
463 }
464
465 retval = ext2fs_bmap2(fs, file->ino, &file->inode,
466 BMAP_BUFFER,
467 bmap_flags,
468 file->blockno, 0,
469 &file->physblock);
470 if (retval) {
471 free(new_block);
472 new_block = NULL;
473 goto fail;
474 }
475
476 if (new_block) {
477 new_block->physblock = file->physblock;
478 ext2fs_hashmap_add(fs->block_sha_map, new_block,
479 new_block->sha, sizeof(new_block->sha));
480 }
481
482 if (bmap_flags & BMAP_SET) {
483 ext2fs_iblk_add_blocks(fs, &file->inode, 1);
484 ext2fs_write_inode(fs, file->ino, &file->inode);
485 }
486 }
487
488 file->pos += c;
489 ptr += c;
490 count += c;
491 nbytes -= c;
492 }
493
494 fail:
495 /* Update inode size */
496 if (count != 0 && EXT2_I_SIZE(&file->inode) < file->pos) {
497 errcode_t rc;
498
499 rc = ext2fs_file_set_size2(file, file->pos);
500 if (retval == 0)
501 retval = rc;
502 }
503
504 if (written)
505 *written = count;
506 return retval;
507 }
508
ext2fs_file_llseek(ext2_file_t file,__u64 offset,int whence,__u64 * ret_pos)509 errcode_t ext2fs_file_llseek(ext2_file_t file, __u64 offset,
510 int whence, __u64 *ret_pos)
511 {
512 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
513
514 if (whence == EXT2_SEEK_SET)
515 file->pos = offset;
516 else if (whence == EXT2_SEEK_CUR)
517 file->pos += offset;
518 else if (whence == EXT2_SEEK_END)
519 file->pos = EXT2_I_SIZE(&file->inode) + offset;
520 else
521 return EXT2_ET_INVALID_ARGUMENT;
522
523 if (ret_pos)
524 *ret_pos = file->pos;
525
526 return 0;
527 }
528
ext2fs_file_lseek(ext2_file_t file,ext2_off_t offset,int whence,ext2_off_t * ret_pos)529 errcode_t ext2fs_file_lseek(ext2_file_t file, ext2_off_t offset,
530 int whence, ext2_off_t *ret_pos)
531 {
532 __u64 loffset, ret_loffset = 0;
533 errcode_t retval;
534
535 loffset = offset;
536 retval = ext2fs_file_llseek(file, loffset, whence, &ret_loffset);
537 if (ret_pos)
538 *ret_pos = (ext2_off_t) ret_loffset;
539 return retval;
540 }
541
542
543 /*
544 * This function returns the size of the file, according to the inode
545 */
ext2fs_file_get_lsize(ext2_file_t file,__u64 * ret_size)546 errcode_t ext2fs_file_get_lsize(ext2_file_t file, __u64 *ret_size)
547 {
548 if (file->magic != EXT2_ET_MAGIC_EXT2_FILE)
549 return EXT2_ET_MAGIC_EXT2_FILE;
550 *ret_size = EXT2_I_SIZE(&file->inode);
551 return 0;
552 }
553
554 /*
555 * This function returns the size of the file, according to the inode
556 */
ext2fs_file_get_size(ext2_file_t file)557 ext2_off_t ext2fs_file_get_size(ext2_file_t file)
558 {
559 __u64 size;
560
561 if (ext2fs_file_get_lsize(file, &size))
562 return 0;
563 if ((size >> 32) != 0)
564 return 0;
565 return size;
566 }
567
568 /* Zero the parts of the last block that are past EOF. */
ext2fs_file_zero_past_offset(ext2_file_t file,ext2_off64_t offset)569 static errcode_t ext2fs_file_zero_past_offset(ext2_file_t file,
570 ext2_off64_t offset)
571 {
572 ext2_filsys fs = file->fs;
573 char *b = NULL;
574 ext2_off64_t off = offset % fs->blocksize;
575 blk64_t blk;
576 int ret_flags;
577 errcode_t retval;
578
579 if (off == 0)
580 return 0;
581
582 retval = sync_buffer_position(file);
583 if (retval)
584 return retval;
585
586 /* Is there an initialized block at the end? */
587 retval = ext2fs_bmap2(fs, file->ino, NULL, NULL, 0,
588 offset / fs->blocksize, &ret_flags, &blk);
589 if (retval)
590 return retval;
591 if ((blk == 0) || (ret_flags & BMAP_RET_UNINIT))
592 return 0;
593
594 /* Zero to the end of the block */
595 retval = ext2fs_get_mem(fs->blocksize, &b);
596 if (retval)
597 return retval;
598
599 /* Read/zero/write block */
600 retval = io_channel_read_blk64(fs->io, blk, 1, b);
601 if (retval)
602 goto out;
603
604 memset(b + off, 0, fs->blocksize - off);
605
606 retval = io_channel_write_blk64(fs->io, blk, 1, b);
607 if (retval)
608 goto out;
609
610 out:
611 ext2fs_free_mem(&b);
612 return retval;
613 }
614
615 /*
616 * This function sets the size of the file, truncating it if necessary
617 *
618 */
ext2fs_file_set_size2(ext2_file_t file,ext2_off64_t size)619 errcode_t ext2fs_file_set_size2(ext2_file_t file, ext2_off64_t size)
620 {
621 ext2_off64_t old_size;
622 errcode_t retval;
623 blk64_t old_truncate, truncate_block;
624
625 EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
626
627 if (size && ext2fs_file_block_offset_too_big(file->fs, &file->inode,
628 (size - 1) / file->fs->blocksize))
629 return EXT2_ET_FILE_TOO_BIG;
630 truncate_block = ((size + file->fs->blocksize - 1) >>
631 EXT2_BLOCK_SIZE_BITS(file->fs->super));
632 old_size = EXT2_I_SIZE(&file->inode);
633 old_truncate = ((old_size + file->fs->blocksize - 1) >>
634 EXT2_BLOCK_SIZE_BITS(file->fs->super));
635
636 retval = ext2fs_inode_size_set(file->fs, &file->inode, size);
637 if (retval)
638 return retval;
639
640 if (file->ino) {
641 retval = ext2fs_write_inode(file->fs, file->ino, &file->inode);
642 if (retval)
643 return retval;
644 }
645
646 retval = ext2fs_file_zero_past_offset(file, size);
647 if (retval)
648 return retval;
649
650 if (truncate_block >= old_truncate)
651 return 0;
652
653 return ext2fs_punch(file->fs, file->ino, &file->inode, 0,
654 truncate_block, ~0ULL);
655 }
656
ext2fs_file_set_size(ext2_file_t file,ext2_off_t size)657 errcode_t ext2fs_file_set_size(ext2_file_t file, ext2_off_t size)
658 {
659 return ext2fs_file_set_size2(file, size);
660 }
661