source: MondoRescue/branches/stable/mindi-busybox/e2fsprogs/ext2fs/unix_io.c@ 821

Last change on this file since 821 was 821, checked in by Bruno Cornec, 18 years ago

Addition of busybox 1.2.1 as a mindi-busybox new package
This should avoid delivering binary files in mindi not built there (Fedora and Debian are quite serious about that)
File size: 16.9 KB
Line 
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#include <stdio.h>
19#include <string.h>
20#if HAVE_UNISTD_H
21#include <unistd.h>
22#endif
23#if HAVE_ERRNO_H
24#include <errno.h>
25#endif
26#include <fcntl.h>
27#include <time.h>
28#ifdef __linux__
29#include <sys/utsname.h>
30#endif
31#if HAVE_SYS_STAT_H
32#include <sys/stat.h>
33#endif
34#if HAVE_SYS_TYPES_H
35#include <sys/types.h>
36#endif
37#include <sys/resource.h>
38
39#include "ext2_fs.h"
40#include "ext2fs.h"
41
42/*
43 * For checking structure magic numbers...
44 */
45
46#define EXT2_CHECK_MAGIC(struct, code) \
47 if ((struct)->magic != (code)) return (code)
48
49struct unix_cache {
50 char *buf;
51 unsigned long block;
52 int access_time;
53 unsigned dirty:1;
54 unsigned in_use:1;
55};
56
57#define CACHE_SIZE 8
58#define WRITE_DIRECT_SIZE 4 /* Must be smaller than CACHE_SIZE */
59#define READ_DIRECT_SIZE 4 /* Should be smaller than CACHE_SIZE */
60
61struct unix_private_data {
62 int magic;
63 int dev;
64 int flags;
65 int access_time;
66 ext2_loff_t offset;
67 struct unix_cache cache[CACHE_SIZE];
68};
69
70static errcode_t unix_open(const char *name, int flags, io_channel *channel);
71static errcode_t unix_close(io_channel channel);
72static errcode_t unix_set_blksize(io_channel channel, int blksize);
73static errcode_t unix_read_blk(io_channel channel, unsigned long block,
74 int count, void *data);
75static errcode_t unix_write_blk(io_channel channel, unsigned long block,
76 int count, const void *data);
77static errcode_t unix_flush(io_channel channel);
78static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
79 int size, const void *data);
80static errcode_t unix_set_option(io_channel channel, const char *option,
81 const char *arg);
82
83static void reuse_cache(io_channel channel, struct unix_private_data *data,
84 struct unix_cache *cache, unsigned long block);
85
86/* __FreeBSD_kernel__ is defined by GNU/kFreeBSD - the FreeBSD kernel
87 * does not know buffered block devices - everything is raw. */
88#if defined(__CYGWIN__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
89#define NEED_BOUNCE_BUFFER
90#else
91#undef NEED_BOUNCE_BUFFER
92#endif
93
94static struct struct_io_manager struct_unix_manager = {
95 EXT2_ET_MAGIC_IO_MANAGER,
96 "Unix I/O Manager",
97 unix_open,
98 unix_close,
99 unix_set_blksize,
100 unix_read_blk,
101 unix_write_blk,
102 unix_flush,
103#ifdef NEED_BOUNCE_BUFFER
104 0,
105#else
106 unix_write_byte,
107#endif
108 unix_set_option
109};
110
111io_manager unix_io_manager = &struct_unix_manager;
112
113/*
114 * Here are the raw I/O functions
115 */
116#ifndef NEED_BOUNCE_BUFFER
117static errcode_t raw_read_blk(io_channel channel,
118 struct unix_private_data *data,
119 unsigned long block,
120 int count, void *buf)
121{
122 errcode_t retval;
123 ssize_t size;
124 ext2_loff_t location;
125 int actual = 0;
126
127 size = (count < 0) ? -count : count * channel->block_size;
128 location = ((ext2_loff_t) block * channel->block_size) + data->offset;
129 if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
130 retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
131 goto error_out;
132 }
133 actual = read(data->dev, buf, size);
134 if (actual != size) {
135 if (actual < 0)
136 actual = 0;
137 retval = EXT2_ET_SHORT_READ;
138 goto error_out;
139 }
140 return 0;
141
142error_out:
143 memset((char *) buf+actual, 0, size-actual);
144 if (channel->read_error)
145 retval = (channel->read_error)(channel, block, count, buf,
146 size, actual, retval);
147 return retval;
148}
149#else /* NEED_BOUNCE_BUFFER */
150/*
151 * Windows and FreeBSD block devices only allow sector alignment IO in offset and size
152 */
153static errcode_t raw_read_blk(io_channel channel,
154 struct unix_private_data *data,
155 unsigned long block,
156 int count, void *buf)
157{
158 errcode_t retval;
159 size_t size, alignsize, fragment;
160 ext2_loff_t location;
161 int total = 0, actual;
162#define BLOCKALIGN 512
163 char sector[BLOCKALIGN];
164
165 size = (count < 0) ? -count : count * channel->block_size;
166 location = ((ext2_loff_t) block * channel->block_size) + data->offset;
167#ifdef DEBUG
168 printf("count=%d, size=%d, block=%d, blk_size=%d, location=%lx\n",
169 count, size, block, channel->block_size, location);
170#endif
171 if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
172 retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
173 goto error_out;
174 }
175 fragment = size % BLOCKALIGN;
176 alignsize = size - fragment;
177 if (alignsize) {
178 actual = read(data->dev, buf, alignsize);
179 if (actual != alignsize)
180 goto short_read;
181 }
182 if (fragment) {
183 actual = read(data->dev, sector, BLOCKALIGN);
184 if (actual != BLOCKALIGN)
185 goto short_read;
186 memcpy(buf+alignsize, sector, fragment);
187 }
188 return 0;
189
190short_read:
191 if (actual>0)
192 total += actual;
193 retval = EXT2_ET_SHORT_READ;
194
195error_out:
196 memset((char *) buf+total, 0, size-actual);
197 if (channel->read_error)
198 retval = (channel->read_error)(channel, block, count, buf,
199 size, actual, retval);
200 return retval;
201}
202#endif
203
204static errcode_t raw_write_blk(io_channel channel,
205 struct unix_private_data *data,
206 unsigned long block,
207 int count, const void *buf)
208{
209 ssize_t size;
210 ext2_loff_t location;
211 int actual = 0;
212 errcode_t retval;
213
214 if (count == 1)
215 size = channel->block_size;
216 else {
217 if (count < 0)
218 size = -count;
219 else
220 size = count * channel->block_size;
221 }
222
223 location = ((ext2_loff_t) block * channel->block_size) + data->offset;
224 if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
225 retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
226 goto error_out;
227 }
228
229 actual = write(data->dev, buf, size);
230 if (actual != size) {
231 retval = EXT2_ET_SHORT_WRITE;
232 goto error_out;
233 }
234 return 0;
235
236error_out:
237 if (channel->write_error)
238 retval = (channel->write_error)(channel, block, count, buf,
239 size, actual, retval);
240 return retval;
241}
242
243
244/*
245 * Here we implement the cache functions
246 */
247
248/* Allocate the cache buffers */
249static errcode_t alloc_cache(io_channel channel,
250 struct unix_private_data *data)
251{
252 errcode_t retval;
253 struct unix_cache *cache;
254 int i;
255
256 data->access_time = 0;
257 for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
258 cache->block = 0;
259 cache->access_time = 0;
260 cache->dirty = 0;
261 cache->in_use = 0;
262 if ((retval = ext2fs_get_mem(channel->block_size,
263 &cache->buf)))
264 return retval;
265 }
266 return 0;
267}
268
269/* Free the cache buffers */
270static void free_cache(struct unix_private_data *data)
271{
272 struct unix_cache *cache;
273 int i;
274
275 data->access_time = 0;
276 for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
277 cache->block = 0;
278 cache->access_time = 0;
279 cache->dirty = 0;
280 cache->in_use = 0;
281 ext2fs_free_mem(&cache->buf);
282 cache->buf = 0;
283 }
284}
285
286#ifndef NO_IO_CACHE
287/*
288 * Try to find a block in the cache. If the block is not found, and
289 * eldest is a non-zero pointer, then fill in eldest with the cache
290 * entry to that should be reused.
291 */
292static struct unix_cache *find_cached_block(struct unix_private_data *data,
293 unsigned long block,
294 struct unix_cache **eldest)
295{
296 struct unix_cache *cache, *unused_cache, *oldest_cache;
297 int i;
298
299 unused_cache = oldest_cache = 0;
300 for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
301 if (!cache->in_use) {
302 if (!unused_cache)
303 unused_cache = cache;
304 continue;
305 }
306 if (cache->block == block) {
307 cache->access_time = ++data->access_time;
308 return cache;
309 }
310 if (!oldest_cache ||
311 (cache->access_time < oldest_cache->access_time))
312 oldest_cache = cache;
313 }
314 if (eldest)
315 *eldest = (unused_cache) ? unused_cache : oldest_cache;
316 return 0;
317}
318
319/*
320 * Reuse a particular cache entry for another block.
321 */
322static void reuse_cache(io_channel channel, struct unix_private_data *data,
323 struct unix_cache *cache, unsigned long block)
324{
325 if (cache->dirty && cache->in_use)
326 raw_write_blk(channel, data, cache->block, 1, cache->buf);
327
328 cache->in_use = 1;
329 cache->dirty = 0;
330 cache->block = block;
331 cache->access_time = ++data->access_time;
332}
333
334/*
335 * Flush all of the blocks in the cache
336 */
337static errcode_t flush_cached_blocks(io_channel channel,
338 struct unix_private_data *data,
339 int invalidate)
340
341{
342 struct unix_cache *cache;
343 errcode_t retval, retval2;
344 int i;
345
346 retval2 = 0;
347 for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
348 if (!cache->in_use)
349 continue;
350
351 if (invalidate)
352 cache->in_use = 0;
353
354 if (!cache->dirty)
355 continue;
356
357 retval = raw_write_blk(channel, data,
358 cache->block, 1, cache->buf);
359 if (retval)
360 retval2 = retval;
361 else
362 cache->dirty = 0;
363 }
364 return retval2;
365}
366#endif /* NO_IO_CACHE */
367
368static errcode_t unix_open(const char *name, int flags, io_channel *channel)
369{
370 io_channel io = NULL;
371 struct unix_private_data *data = NULL;
372 errcode_t retval;
373 int open_flags;
374 struct stat st;
375#ifdef __linux__
376 struct utsname ut;
377#endif
378
379 if (name == 0)
380 return EXT2_ET_BAD_DEVICE_NAME;
381 retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
382 if (retval)
383 return retval;
384 memset(io, 0, sizeof(struct struct_io_channel));
385 io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
386 retval = ext2fs_get_mem(sizeof(struct unix_private_data), &data);
387 if (retval)
388 goto cleanup;
389
390 io->manager = unix_io_manager;
391 retval = ext2fs_get_mem(strlen(name)+1, &io->name);
392 if (retval)
393 goto cleanup;
394
395 strcpy(io->name, name);
396 io->private_data = data;
397 io->block_size = 1024;
398 io->read_error = 0;
399 io->write_error = 0;
400 io->refcount = 1;
401
402 memset(data, 0, sizeof(struct unix_private_data));
403 data->magic = EXT2_ET_MAGIC_UNIX_IO_CHANNEL;
404
405 if ((retval = alloc_cache(io, data)))
406 goto cleanup;
407
408 open_flags = (flags & IO_FLAG_RW) ? O_RDWR : O_RDONLY;
409#ifdef CONFIG_LFS
410 data->dev = open64(io->name, open_flags);
411#else
412 data->dev = open(io->name, open_flags);
413#endif
414 if (data->dev < 0) {
415 retval = errno;
416 goto cleanup;
417 }
418
419#ifdef __linux__
420#undef RLIM_INFINITY
421#if (defined(__alpha__) || ((defined(__sparc__) || defined(__mips__)) && (SIZEOF_LONG == 4)))
422#define RLIM_INFINITY ((unsigned long)(~0UL>>1))
423#else
424#define RLIM_INFINITY (~0UL)
425#endif
426 /*
427 * Work around a bug in 2.4.10-2.4.18 kernels where writes to
428 * block devices are wrongly getting hit by the filesize
429 * limit. This workaround isn't perfect, since it won't work
430 * if glibc wasn't built against 2.2 header files. (Sigh.)
431 *
432 */
433 if ((flags & IO_FLAG_RW) &&
434 (uname(&ut) == 0) &&
435 ((ut.release[0] == '2') && (ut.release[1] == '.') &&
436 (ut.release[2] == '4') && (ut.release[3] == '.') &&
437 (ut.release[4] == '1') && (ut.release[5] >= '0') &&
438 (ut.release[5] < '8')) &&
439 (fstat(data->dev, &st) == 0) &&
440 (S_ISBLK(st.st_mode))) {
441 struct rlimit rlim;
442
443 rlim.rlim_cur = rlim.rlim_max = (unsigned long) RLIM_INFINITY;
444 setrlimit(RLIMIT_FSIZE, &rlim);
445 getrlimit(RLIMIT_FSIZE, &rlim);
446 if (((unsigned long) rlim.rlim_cur) <
447 ((unsigned long) rlim.rlim_max)) {
448 rlim.rlim_cur = rlim.rlim_max;
449 setrlimit(RLIMIT_FSIZE, &rlim);
450 }
451 }
452#endif
453 *channel = io;
454 return 0;
455
456cleanup:
457 if (data) {
458 free_cache(data);
459 ext2fs_free_mem(&data);
460 }
461 ext2fs_free_mem(&io);
462 return retval;
463}
464
465static errcode_t unix_close(io_channel channel)
466{
467 struct unix_private_data *data;
468 errcode_t retval = 0;
469
470 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
471 data = (struct unix_private_data *) channel->private_data;
472 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
473
474 if (--channel->refcount > 0)
475 return 0;
476
477#ifndef NO_IO_CACHE
478 retval = flush_cached_blocks(channel, data, 0);
479#endif
480
481 if (close(data->dev) < 0)
482 retval = errno;
483 free_cache(data);
484
485 ext2fs_free_mem(&channel->private_data);
486 ext2fs_free_mem(&channel->name);
487 ext2fs_free_mem(&channel);
488 return retval;
489}
490
491static errcode_t unix_set_blksize(io_channel channel, int blksize)
492{
493 struct unix_private_data *data;
494 errcode_t retval;
495
496 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
497 data = (struct unix_private_data *) channel->private_data;
498 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
499
500 if (channel->block_size != blksize) {
501#ifndef NO_IO_CACHE
502 if ((retval = flush_cached_blocks(channel, data, 0)))
503 return retval;
504#endif
505
506 channel->block_size = blksize;
507 free_cache(data);
508 if ((retval = alloc_cache(channel, data)))
509 return retval;
510 }
511 return 0;
512}
513
514
515static errcode_t unix_read_blk(io_channel channel, unsigned long block,
516 int count, void *buf)
517{
518 struct unix_private_data *data;
519 struct unix_cache *cache, *reuse[READ_DIRECT_SIZE];
520 errcode_t retval;
521 char *cp;
522 int i, j;
523
524 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
525 data = (struct unix_private_data *) channel->private_data;
526 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
527
528#ifdef NO_IO_CACHE
529 return raw_read_blk(channel, data, block, count, buf);
530#else
531 /*
532 * If we're doing an odd-sized read or a very large read,
533 * flush out the cache and then do a direct read.
534 */
535 if (count < 0 || count > WRITE_DIRECT_SIZE) {
536 if ((retval = flush_cached_blocks(channel, data, 0)))
537 return retval;
538 return raw_read_blk(channel, data, block, count, buf);
539 }
540
541 cp = buf;
542 while (count > 0) {
543 /* If it's in the cache, use it! */
544 if ((cache = find_cached_block(data, block, &reuse[0]))) {
545#ifdef DEBUG
546 printf("Using cached block %d\n", block);
547#endif
548 memcpy(cp, cache->buf, channel->block_size);
549 count--;
550 block++;
551 cp += channel->block_size;
552 continue;
553 }
554 /*
555 * Find the number of uncached blocks so we can do a
556 * single read request
557 */
558 for (i=1; i < count; i++)
559 if (find_cached_block(data, block+i, &reuse[i]))
560 break;
561#ifdef DEBUG
562 printf("Reading %d blocks starting at %d\n", i, block);
563#endif
564 if ((retval = raw_read_blk(channel, data, block, i, cp)))
565 return retval;
566
567 /* Save the results in the cache */
568 for (j=0; j < i; j++) {
569 count--;
570 cache = reuse[j];
571 reuse_cache(channel, data, cache, block++);
572 memcpy(cache->buf, cp, channel->block_size);
573 cp += channel->block_size;
574 }
575 }
576 return 0;
577#endif /* NO_IO_CACHE */
578}
579
580static errcode_t unix_write_blk(io_channel channel, unsigned long block,
581 int count, const void *buf)
582{
583 struct unix_private_data *data;
584 struct unix_cache *cache, *reuse;
585 errcode_t retval = 0;
586 const char *cp;
587 int writethrough;
588
589 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
590 data = (struct unix_private_data *) channel->private_data;
591 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
592
593#ifdef NO_IO_CACHE
594 return raw_write_blk(channel, data, block, count, buf);
595#else
596 /*
597 * If we're doing an odd-sized write or a very large write,
598 * flush out the cache completely and then do a direct write.
599 */
600 if (count < 0 || count > WRITE_DIRECT_SIZE) {
601 if ((retval = flush_cached_blocks(channel, data, 1)))
602 return retval;
603 return raw_write_blk(channel, data, block, count, buf);
604 }
605
606 /*
607 * For a moderate-sized multi-block write, first force a write
608 * if we're in write-through cache mode, and then fill the
609 * cache with the blocks.
610 */
611 writethrough = channel->flags & CHANNEL_FLAGS_WRITETHROUGH;
612 if (writethrough)
613 retval = raw_write_blk(channel, data, block, count, buf);
614
615 cp = buf;
616 while (count > 0) {
617 cache = find_cached_block(data, block, &reuse);
618 if (!cache) {
619 cache = reuse;
620 reuse_cache(channel, data, cache, block);
621 }
622 memcpy(cache->buf, cp, channel->block_size);
623 cache->dirty = !writethrough;
624 count--;
625 block++;
626 cp += channel->block_size;
627 }
628 return retval;
629#endif /* NO_IO_CACHE */
630}
631
632static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
633 int size, const void *buf)
634{
635 struct unix_private_data *data;
636 errcode_t retval = 0;
637 ssize_t actual;
638
639 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
640 data = (struct unix_private_data *) channel->private_data;
641 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
642
643#ifndef NO_IO_CACHE
644 /*
645 * Flush out the cache completely
646 */
647 if ((retval = flush_cached_blocks(channel, data, 1)))
648 return retval;
649#endif
650
651 if (lseek(data->dev, offset + data->offset, SEEK_SET) < 0)
652 return errno;
653
654 actual = write(data->dev, buf, size);
655 if (actual != size)
656 return EXT2_ET_SHORT_WRITE;
657
658 return 0;
659}
660
661/*
662 * Flush data buffers to disk.
663 */
664static errcode_t unix_flush(io_channel channel)
665{
666 struct unix_private_data *data;
667 errcode_t retval = 0;
668
669 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
670 data = (struct unix_private_data *) channel->private_data;
671 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
672
673#ifndef NO_IO_CACHE
674 retval = flush_cached_blocks(channel, data, 0);
675#endif
676 fsync(data->dev);
677 return retval;
678}
679
680static errcode_t unix_set_option(io_channel channel, const char *option,
681 const char *arg)
682{
683 struct unix_private_data *data;
684 unsigned long tmp;
685 char *end;
686
687 EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
688 data = (struct unix_private_data *) channel->private_data;
689 EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
690
691 if (!strcmp(option, "offset")) {
692 if (!arg)
693 return EXT2_ET_INVALID_ARGUMENT;
694
695 tmp = strtoul(arg, &end, 0);
696 if (*end)
697 return EXT2_ET_INVALID_ARGUMENT;
698 data->offset = tmp;
699 return 0;
700 }
701 return EXT2_ET_INVALID_ARGUMENT;
702}
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