1 /*
2 * unix_io.c --- This is the Unix (well, really POSIX) implementation
3 * of the I/O manager.
4 *
5 * Implements a one-block write-through cache.
6 *
7 * Includes support for Windows NT support under Cygwin.
8 *
9 * Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
10 * 2002 by Theodore Ts'o.
11 *
12 * %Begin-Header%
13 * This file may be redistributed under the terms of the GNU Public
14 * License.
15 * %End-Header%
16 */
17
18 #define _LARGEFILE_SOURCE
19 #define _LARGEFILE64_SOURCE
20
21 #include <stdio.h>
22 #include <string.h>
23 #if HAVE_UNISTD_H
24 #include <unistd.h>
25 #endif
26 #if HAVE_ERRNO_H
27 #include <errno.h>
28 #endif
29 #include <fcntl.h>
30 #include <time.h>
31 #ifdef __linux__
32 #include <sys/utsname.h>
33 #endif
34 #ifdef HAVE_SYS_IOCTL_H
35 #include <sys/ioctl.h>
36 #endif
37 #ifdef HAVE_SYS_MOUNT_H
38 #include <sys/mount.h>
39 #endif
40 #if HAVE_SYS_STAT_H
41 #include <sys/stat.h>
42 #endif
43 #if HAVE_SYS_TYPES_H
44 #include <sys/types.h>
45 #endif
46 #if HAVE_SYS_RESOURCE_H
47 #include <sys/resource.h>
48 #endif
49
50 #if defined(__linux__) && defined(_IO) && !defined(BLKGETSIZE)
51 #define BLKROGET _IO(0x12, 94) /* Get read-only status (0 = read_write). */
52 #endif
53
54 #include "ext2_fs.h"
55 #include "ext2fs.h"
56
57 /*
58 * For checking structure magic numbers...
59 */
60
61 #define EXT2_CHECK_MAGIC(struct, code) \
62 if ((struct)->magic != (code)) return (code)
63
64 struct unix_cache {
65 char *buf;
66 unsigned long block;
67 int access_time;
68 unsigned dirty:1;
69 unsigned in_use:1;
70 };
71
72 #define CACHE_SIZE 8
73 #define WRITE_DIRECT_SIZE 4 /* Must be smaller than CACHE_SIZE */
74 #define READ_DIRECT_SIZE 4 /* Should be smaller than CACHE_SIZE */
75
76 struct unix_private_data {
77 int magic;
78 int dev;
79 int flags;
80 int access_time;
81 ext2_loff_t offset;
82 struct unix_cache cache[CACHE_SIZE];
83 struct struct_io_stats io_stats;
84 };
85
86 static errcode_t unix_open(const char *name, int flags, io_channel *channel);
87 static errcode_t unix_close(io_channel channel);
88 static errcode_t unix_set_blksize(io_channel channel, int blksize);
89 static errcode_t unix_read_blk(io_channel channel, unsigned long block,
90 int count, void *data);
91 static errcode_t unix_write_blk(io_channel channel, unsigned long block,
92 int count, const void *data);
93 static errcode_t unix_flush(io_channel channel);
94 static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
95 int size, const void *data);
96 static errcode_t unix_set_option(io_channel channel, const char *option,
97 const char *arg);
98 static errcode_t unix_get_stats(io_channel channel, io_stats *stats)
99 ;
100 static void reuse_cache(io_channel channel, struct unix_private_data *data,
101 struct unix_cache *cache, unsigned long long block);
102 static errcode_t unix_read_blk64(io_channel channel, unsigned long long block,
103 int count, void *data);
104 static errcode_t unix_write_blk64(io_channel channel, unsigned long long block,
105 int count, const void *data);
106
107 /* __FreeBSD_kernel__ is defined by GNU/kFreeBSD - the FreeBSD kernel
108 * does not know buffered block devices - everything is raw. */
109 #if defined(__CYGWIN__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
110 #define NEED_BOUNCE_BUFFER
111 #else
112 #undef NEED_BOUNCE_BUFFER
113 #endif
114
115 static struct struct_io_manager struct_unix_manager = {
116 EXT2_ET_MAGIC_IO_MANAGER,
117 "Unix I/O Manager",
118 unix_open,
119 unix_close,
120 unix_set_blksize,
121 unix_read_blk,
122 unix_write_blk,
123 unix_flush,
124 #ifdef NEED_BOUNCE_BUFFER
125 0,
126 #else
127 unix_write_byte,
128 #endif
129 unix_set_option,
130 unix_get_stats,
131 unix_read_blk64,
132 unix_write_blk64,
133 };
134
135 io_manager unix_io_manager = &struct_unix_manager;
136
unix_get_stats(io_channel channel,io_stats * stats)137 static errcode_t unix_get_stats(io_channel channel, io_stats *stats)
138 {
139 errcode_t retval = 0;
140
141 struct unix_private_data *data;
142
143 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
144 data = (struct unix_private_data *) channel->private_data;
145 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
146
147 if (stats)
148 *stats = &data->io_stats;
149
150 return retval;
151 }
152
153 /*
154 * Here are the raw I/O functions
155 */
156 #ifndef NEED_BOUNCE_BUFFER
raw_read_blk(io_channel channel,struct unix_private_data * data,unsigned long long block,int count,void * buf)157 static errcode_t raw_read_blk(io_channel channel,
158 struct unix_private_data *data,
159 unsigned long long block,
160 int count, void *buf)
161 {
162 errcode_t retval;
163 ssize_t size;
164 ext2_loff_t location;
165 int actual = 0;
166
167 size = (count < 0) ? -count : count * channel->block_size;
168 data->io_stats.bytes_read += size;
169 location = ((ext2_loff_t) block * channel->block_size) + data->offset;
170 if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
171 retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
172 goto error_out;
173 }
174 actual = read(data->dev, buf, size);
175 if (actual != size) {
176 if (actual < 0)
177 actual = 0;
178 retval = EXT2_ET_SHORT_READ;
179 goto error_out;
180 }
181 return 0;
182
183 error_out:
184 memset((char *) buf+actual, 0, size-actual);
185 if (channel->read_error)
186 retval = (channel->read_error)(channel, block, count, buf,
187 size, actual, retval);
188 return retval;
189 }
190 #else /* NEED_BOUNCE_BUFFER */
191 /*
192 * Windows and FreeBSD block devices only allow sector alignment IO in offset and size
193 */
raw_read_blk(io_channel channel,struct unix_private_data * data,unsigned long block,int count,void * buf)194 static errcode_t raw_read_blk(io_channel channel,
195 struct unix_private_data *data,
196 unsigned long block,
197 int count, void *buf)
198 {
199 errcode_t retval;
200 size_t size, alignsize, fragment;
201 ext2_loff_t location;
202 int total = 0, actual;
203 #define BLOCKALIGN 512
204 char sector[BLOCKALIGN];
205
206 size = (count < 0) ? -count : count * channel->block_size;
207 data->io_stats.bytes_read += size;
208 location = ((ext2_loff_t) block * channel->block_size) + data->offset;
209 #ifdef DEBUG
210 printf("count=%d, size=%d, block=%lu, blk_size=%d, location=%llx\n",
211 count, size, block, channel->block_size, (long long)location);
212 #endif
213 if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
214 retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
215 goto error_out;
216 }
217 fragment = size % BLOCKALIGN;
218 alignsize = size - fragment;
219 if (alignsize) {
220 actual = read(data->dev, buf, alignsize);
221 if (actual != alignsize)
222 goto short_read;
223 }
224 if (fragment) {
225 actual = read(data->dev, sector, BLOCKALIGN);
226 if (actual != BLOCKALIGN)
227 goto short_read;
228 memcpy(buf+alignsize, sector, fragment);
229 }
230 return 0;
231
232 short_read:
233 if (actual>0)
234 total += actual;
235 retval = EXT2_ET_SHORT_READ;
236
237 error_out:
238 memset((char *) buf+total, 0, size-actual);
239 if (channel->read_error)
240 retval = (channel->read_error)(channel, block, count, buf,
241 size, actual, retval);
242 return retval;
243 }
244 #endif
245
raw_write_blk(io_channel channel,struct unix_private_data * data,unsigned long long block,int count,const void * buf)246 static errcode_t raw_write_blk(io_channel channel,
247 struct unix_private_data *data,
248 unsigned long long block,
249 int count, const void *buf)
250 {
251 ssize_t size;
252 ext2_loff_t location;
253 int actual = 0;
254 errcode_t retval;
255
256 if (count == 1)
257 size = channel->block_size;
258 else {
259 if (count < 0)
260 size = -count;
261 else
262 size = count * channel->block_size;
263 }
264 data->io_stats.bytes_written += size;
265
266 location = ((ext2_loff_t) block * channel->block_size) + data->offset;
267 if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
268 retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
269 goto error_out;
270 }
271
272 actual = write(data->dev, buf, size);
273 if (actual != size) {
274 retval = EXT2_ET_SHORT_WRITE;
275 goto error_out;
276 }
277 return 0;
278
279 error_out:
280 if (channel->write_error)
281 retval = (channel->write_error)(channel, block, count, buf,
282 size, actual, retval);
283 return retval;
284 }
285
286
287 /*
288 * Here we implement the cache functions
289 */
290
291 /* Allocate the cache buffers */
alloc_cache(io_channel channel,struct unix_private_data * data)292 static errcode_t alloc_cache(io_channel channel,
293 struct unix_private_data *data)
294 {
295 errcode_t retval;
296 struct unix_cache *cache;
297 int i;
298
299 data->access_time = 0;
300 for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
301 cache->block = 0;
302 cache->access_time = 0;
303 cache->dirty = 0;
304 cache->in_use = 0;
305 if ((retval = ext2fs_get_mem(channel->block_size,
306 &cache->buf)))
307 return retval;
308 }
309 return 0;
310 }
311
312 /* Free the cache buffers */
free_cache(struct unix_private_data * data)313 static void free_cache(struct unix_private_data *data)
314 {
315 struct unix_cache *cache;
316 int i;
317
318 data->access_time = 0;
319 for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
320 cache->block = 0;
321 cache->access_time = 0;
322 cache->dirty = 0;
323 cache->in_use = 0;
324 if (cache->buf)
325 ext2fs_free_mem(&cache->buf);
326 cache->buf = 0;
327 }
328 }
329
330 #ifndef NO_IO_CACHE
331 /*
332 * Try to find a block in the cache. If the block is not found, and
333 * eldest is a non-zero pointer, then fill in eldest with the cache
334 * entry to that should be reused.
335 */
find_cached_block(struct unix_private_data * data,unsigned long long block,struct unix_cache ** eldest)336 static struct unix_cache *find_cached_block(struct unix_private_data *data,
337 unsigned long long block,
338 struct unix_cache **eldest)
339 {
340 struct unix_cache *cache, *unused_cache, *oldest_cache;
341 int i;
342
343 unused_cache = oldest_cache = 0;
344 for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
345 if (!cache->in_use) {
346 if (!unused_cache)
347 unused_cache = cache;
348 continue;
349 }
350 if (cache->block == block) {
351 cache->access_time = ++data->access_time;
352 return cache;
353 }
354 if (!oldest_cache ||
355 (cache->access_time < oldest_cache->access_time))
356 oldest_cache = cache;
357 }
358 if (eldest)
359 *eldest = (unused_cache) ? unused_cache : oldest_cache;
360 return 0;
361 }
362
363 /*
364 * Reuse a particular cache entry for another block.
365 */
reuse_cache(io_channel channel,struct unix_private_data * data,struct unix_cache * cache,unsigned long long block)366 static void reuse_cache(io_channel channel, struct unix_private_data *data,
367 struct unix_cache *cache, unsigned long long block)
368 {
369 if (cache->dirty && cache->in_use)
370 raw_write_blk(channel, data, cache->block, 1, cache->buf);
371
372 cache->in_use = 1;
373 cache->dirty = 0;
374 cache->block = block;
375 cache->access_time = ++data->access_time;
376 }
377
378 /*
379 * Flush all of the blocks in the cache
380 */
flush_cached_blocks(io_channel channel,struct unix_private_data * data,int invalidate)381 static errcode_t flush_cached_blocks(io_channel channel,
382 struct unix_private_data *data,
383 int invalidate)
384
385 {
386 struct unix_cache *cache;
387 errcode_t retval, retval2;
388 int i;
389
390 retval2 = 0;
391 for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
392 if (!cache->in_use)
393 continue;
394
395 if (invalidate)
396 cache->in_use = 0;
397
398 if (!cache->dirty)
399 continue;
400
401 retval = raw_write_blk(channel, data,
402 cache->block, 1, cache->buf);
403 if (retval)
404 retval2 = retval;
405 else
406 cache->dirty = 0;
407 }
408 return retval2;
409 }
410 #endif /* NO_IO_CACHE */
411
unix_open(const char * name,int flags,io_channel * channel)412 static errcode_t unix_open(const char *name, int flags, io_channel *channel)
413 {
414 io_channel io = NULL;
415 struct unix_private_data *data = NULL;
416 errcode_t retval;
417 int open_flags;
418 struct stat st;
419 #ifdef __linux__
420 struct utsname ut;
421 #endif
422
423 if (name == 0)
424 return EXT2_ET_BAD_DEVICE_NAME;
425 retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
426 if (retval)
427 return retval;
428 memset(io, 0, sizeof(struct struct_io_channel));
429 io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
430 retval = ext2fs_get_mem(sizeof(struct unix_private_data), &data);
431 if (retval)
432 goto cleanup;
433
434 io->manager = unix_io_manager;
435 retval = ext2fs_get_mem(strlen(name)+1, &io->name);
436 if (retval)
437 goto cleanup;
438
439 strcpy(io->name, name);
440 io->private_data = data;
441 io->block_size = 1024;
442 io->read_error = 0;
443 io->write_error = 0;
444 io->refcount = 1;
445
446 memset(data, 0, sizeof(struct unix_private_data));
447 data->magic = EXT2_ET_MAGIC_UNIX_IO_CHANNEL;
448 data->io_stats.num_fields = 2;
449
450 if ((retval = alloc_cache(io, data)))
451 goto cleanup;
452
453 open_flags = (flags & IO_FLAG_RW) ? O_RDWR : O_RDONLY;
454 if (flags & IO_FLAG_EXCLUSIVE)
455 open_flags |= O_EXCL;
456 #ifdef HAVE_OPEN64
457 data->dev = open64(io->name, open_flags);
458 #else
459 data->dev = open(io->name, open_flags);
460 #endif
461 if (data->dev < 0) {
462 retval = errno;
463 goto cleanup;
464 }
465
466 #ifdef BLKROGET
467 if (flags & IO_FLAG_RW) {
468 int error;
469 int readonly = 0;
470
471 /* Is the block device actually writable? */
472 error = ioctl(data->dev, BLKROGET, &readonly);
473 if (!error && readonly) {
474 close(data->dev);
475 retval = EPERM;
476 goto cleanup;
477 }
478 }
479 #endif
480
481 #ifdef __linux__
482 #undef RLIM_INFINITY
483 #if (defined(__alpha__) || ((defined(__sparc__) || defined(__mips__)) && (SIZEOF_LONG == 4)))
484 #define RLIM_INFINITY ((unsigned long)(~0UL>>1))
485 #else
486 #define RLIM_INFINITY (~0UL)
487 #endif
488 /*
489 * Work around a bug in 2.4.10-2.4.18 kernels where writes to
490 * block devices are wrongly getting hit by the filesize
491 * limit. This workaround isn't perfect, since it won't work
492 * if glibc wasn't built against 2.2 header files. (Sigh.)
493 *
494 */
495 if ((flags & IO_FLAG_RW) &&
496 (uname(&ut) == 0) &&
497 ((ut.release[0] == '2') && (ut.release[1] == '.') &&
498 (ut.release[2] == '4') && (ut.release[3] == '.') &&
499 (ut.release[4] == '1') && (ut.release[5] >= '0') &&
500 (ut.release[5] < '8')) &&
501 (fstat(data->dev, &st) == 0) &&
502 (S_ISBLK(st.st_mode))) {
503 struct rlimit rlim;
504
505 rlim.rlim_cur = rlim.rlim_max = (unsigned long) RLIM_INFINITY;
506 setrlimit(RLIMIT_FSIZE, &rlim);
507 getrlimit(RLIMIT_FSIZE, &rlim);
508 if (((unsigned long) rlim.rlim_cur) <
509 ((unsigned long) rlim.rlim_max)) {
510 rlim.rlim_cur = rlim.rlim_max;
511 setrlimit(RLIMIT_FSIZE, &rlim);
512 }
513 }
514 #endif
515 *channel = io;
516 return 0;
517
518 cleanup:
519 if (data) {
520 free_cache(data);
521 ext2fs_free_mem(&data);
522 }
523 if (io)
524 ext2fs_free_mem(&io);
525 return retval;
526 }
527
unix_close(io_channel channel)528 static errcode_t unix_close(io_channel channel)
529 {
530 struct unix_private_data *data;
531 errcode_t retval = 0;
532
533 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
534 data = (struct unix_private_data *) channel->private_data;
535 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
536
537 if (--channel->refcount > 0)
538 return 0;
539
540 #ifndef NO_IO_CACHE
541 retval = flush_cached_blocks(channel, data, 0);
542 #endif
543
544 if (close(data->dev) < 0)
545 retval = errno;
546 free_cache(data);
547
548 ext2fs_free_mem(&channel->private_data);
549 if (channel->name)
550 ext2fs_free_mem(&channel->name);
551 ext2fs_free_mem(&channel);
552 return retval;
553 }
554
unix_set_blksize(io_channel channel,int blksize)555 static errcode_t unix_set_blksize(io_channel channel, int blksize)
556 {
557 struct unix_private_data *data;
558 errcode_t retval;
559
560 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
561 data = (struct unix_private_data *) channel->private_data;
562 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
563
564 if (channel->block_size != blksize) {
565 #ifndef NO_IO_CACHE
566 if ((retval = flush_cached_blocks(channel, data, 0)))
567 return retval;
568 #endif
569
570 channel->block_size = blksize;
571 free_cache(data);
572 if ((retval = alloc_cache(channel, data)))
573 return retval;
574 }
575 return 0;
576 }
577
578
unix_read_blk64(io_channel channel,unsigned long long block,int count,void * buf)579 static errcode_t unix_read_blk64(io_channel channel, unsigned long long block,
580 int count, void *buf)
581 {
582 struct unix_private_data *data;
583 struct unix_cache *cache, *reuse[READ_DIRECT_SIZE];
584 errcode_t retval;
585 char *cp;
586 int i, j;
587
588 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
589 data = (struct unix_private_data *) channel->private_data;
590 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
591
592 #ifdef NO_IO_CACHE
593 return raw_read_blk(channel, data, block, count, buf);
594 #else
595 /*
596 * If we're doing an odd-sized read or a very large read,
597 * flush out the cache and then do a direct read.
598 */
599 if (count < 0 || count > WRITE_DIRECT_SIZE) {
600 if ((retval = flush_cached_blocks(channel, data, 0)))
601 return retval;
602 return raw_read_blk(channel, data, block, count, buf);
603 }
604
605 cp = buf;
606 while (count > 0) {
607 /* If it's in the cache, use it! */
608 if ((cache = find_cached_block(data, block, &reuse[0]))) {
609 #ifdef DEBUG
610 printf("Using cached block %lu\n", block);
611 #endif
612 memcpy(cp, cache->buf, channel->block_size);
613 count--;
614 block++;
615 cp += channel->block_size;
616 continue;
617 }
618 /*
619 * Find the number of uncached blocks so we can do a
620 * single read request
621 */
622 for (i=1; i < count; i++)
623 if (find_cached_block(data, block+i, &reuse[i]))
624 break;
625 #ifdef DEBUG
626 printf("Reading %d blocks starting at %lu\n", i, block);
627 #endif
628 if ((retval = raw_read_blk(channel, data, block, i, cp)))
629 return retval;
630
631 /* Save the results in the cache */
632 for (j=0; j < i; j++) {
633 count--;
634 cache = reuse[j];
635 reuse_cache(channel, data, cache, block++);
636 memcpy(cache->buf, cp, channel->block_size);
637 cp += channel->block_size;
638 }
639 }
640 return 0;
641 #endif /* NO_IO_CACHE */
642 }
643
unix_read_blk(io_channel channel,unsigned long block,int count,void * buf)644 static errcode_t unix_read_blk(io_channel channel, unsigned long block,
645 int count, void *buf)
646 {
647 return unix_read_blk64(channel, block, count, buf);
648 }
649
unix_write_blk64(io_channel channel,unsigned long long block,int count,const void * buf)650 static errcode_t unix_write_blk64(io_channel channel, unsigned long long block,
651 int count, const void *buf)
652 {
653 struct unix_private_data *data;
654 struct unix_cache *cache, *reuse;
655 errcode_t retval = 0;
656 const char *cp;
657 int writethrough;
658
659 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
660 data = (struct unix_private_data *) channel->private_data;
661 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
662
663 #ifdef NO_IO_CACHE
664 return raw_write_blk(channel, data, block, count, buf);
665 #else
666 /*
667 * If we're doing an odd-sized write or a very large write,
668 * flush out the cache completely and then do a direct write.
669 */
670 if (count < 0 || count > WRITE_DIRECT_SIZE) {
671 if ((retval = flush_cached_blocks(channel, data, 1)))
672 return retval;
673 return raw_write_blk(channel, data, block, count, buf);
674 }
675
676 /*
677 * For a moderate-sized multi-block write, first force a write
678 * if we're in write-through cache mode, and then fill the
679 * cache with the blocks.
680 */
681 writethrough = channel->flags & CHANNEL_FLAGS_WRITETHROUGH;
682 if (writethrough)
683 retval = raw_write_blk(channel, data, block, count, buf);
684
685 cp = buf;
686 while (count > 0) {
687 cache = find_cached_block(data, block, &reuse);
688 if (!cache) {
689 cache = reuse;
690 reuse_cache(channel, data, cache, block);
691 }
692 memcpy(cache->buf, cp, channel->block_size);
693 cache->dirty = !writethrough;
694 count--;
695 block++;
696 cp += channel->block_size;
697 }
698 return retval;
699 #endif /* NO_IO_CACHE */
700 }
701
unix_write_blk(io_channel channel,unsigned long block,int count,const void * buf)702 static errcode_t unix_write_blk(io_channel channel, unsigned long block,
703 int count, const void *buf)
704 {
705 return unix_write_blk64(channel, block, count, buf);
706 }
707
unix_write_byte(io_channel channel,unsigned long offset,int size,const void * buf)708 static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
709 int size, const void *buf)
710 {
711 struct unix_private_data *data;
712 errcode_t retval = 0;
713 ssize_t actual;
714
715 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
716 data = (struct unix_private_data *) channel->private_data;
717 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
718
719 #ifndef NO_IO_CACHE
720 /*
721 * Flush out the cache completely
722 */
723 if ((retval = flush_cached_blocks(channel, data, 1)))
724 return retval;
725 #endif
726
727 if (lseek(data->dev, offset + data->offset, SEEK_SET) < 0)
728 return errno;
729
730 actual = write(data->dev, buf, size);
731 if (actual != size)
732 return EXT2_ET_SHORT_WRITE;
733
734 return 0;
735 }
736
737 /*
738 * Flush data buffers to disk.
739 */
unix_flush(io_channel channel)740 static errcode_t unix_flush(io_channel channel)
741 {
742 struct unix_private_data *data;
743 errcode_t retval = 0;
744
745 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
746 data = (struct unix_private_data *) channel->private_data;
747 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
748
749 #ifndef NO_IO_CACHE
750 retval = flush_cached_blocks(channel, data, 0);
751 #endif
752 fsync(data->dev);
753 return retval;
754 }
755
unix_set_option(io_channel channel,const char * option,const char * arg)756 static errcode_t unix_set_option(io_channel channel, const char *option,
757 const char *arg)
758 {
759 struct unix_private_data *data;
760 unsigned long long tmp;
761 char *end;
762
763 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
764 data = (struct unix_private_data *) channel->private_data;
765 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
766
767 if (!strcmp(option, "offset")) {
768 if (!arg)
769 return EXT2_ET_INVALID_ARGUMENT;
770
771 tmp = strtoull(arg, &end, 0);
772 if (*end)
773 return EXT2_ET_INVALID_ARGUMENT;
774 data->offset = tmp;
775 if (data->offset < 0)
776 return EXT2_ET_INVALID_ARGUMENT;
777 return 0;
778 }
779 return EXT2_ET_INVALID_ARGUMENT;
780 }
781