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
ext2fs_file_open2(ext2_filsys fs,ext2_ino_t ino,struct ext2_inode * inode,int flags,ext2_file_t * ret)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
ext2fs_file_open(ext2_filsys fs,ext2_ino_t ino,int flags,ext2_file_t * ret)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 */
ext2fs_file_get_fs(ext2_file_t file)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 */
ext2fs_file_get_inode(ext2_file_t file)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 */
ext2fs_file_get_inode_num(ext2_file_t file)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 */
ext2fs_file_flush(ext2_file_t file)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 */
sync_buffer_position(ext2_file_t file)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
load_buffer(ext2_file_t file,int dontfill)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
ext2fs_file_close(ext2_file_t file)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
ext2fs_file_read_inline_data(ext2_file_t file,void * buf,unsigned int wanted,unsigned int * got)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
ext2fs_file_read(ext2_file_t file,void * buf,unsigned int wanted,unsigned int * got)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
ext2fs_file_write_inline_data(ext2_file_t file,const void * buf,unsigned int nbytes,unsigned int * written)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
ext2fs_file_write(ext2_file_t file,const void * buf,unsigned int nbytes,unsigned int * written)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
ext2fs_file_llseek(ext2_file_t file,__u64 offset,int whence,__u64 * ret_pos)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
ext2fs_file_lseek(ext2_file_t file,ext2_off_t offset,int whence,ext2_off_t * ret_pos)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 */
ext2fs_file_get_lsize(ext2_file_t file,__u64 * ret_size)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 */
ext2fs_file_get_size(ext2_file_t file)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. */
ext2fs_file_zero_past_offset(ext2_file_t file,ext2_off64_t offset)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 */
ext2fs_file_set_size2(ext2_file_t file,ext2_off64_t size)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
ext2fs_file_set_size(ext2_file_t file,ext2_off_t size)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 }
616