block.c 13.2 KB
Newer Older
bellard's avatar
bellard committed
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
/*
 * QEMU System Emulator block driver
 * 
 * Copyright (c) 2003 Fabrice Bellard
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#include "vl.h"

bellard's avatar
bellard committed
26
27
28
#ifndef _WIN32
#include <sys/mman.h>
#endif
29

bellard's avatar
bellard committed
30
31
#include "cow.h"

bellard's avatar
bellard committed
32
struct BlockDriverState {
33
    int fd; /* if -1, only COW mappings */
bellard's avatar
bellard committed
34
    int64_t total_sectors;
bellard's avatar
bellard committed
35
36
37
38
39
40
41
    int read_only; /* if true, the media is read only */
    int inserted; /* if true, the media is present */
    int removable; /* if true, the media can be removed */
    int locked;    /* if true, the media cannot temporarily be ejected */
    /* event callback when inserting/removing */
    void (*change_cb)(void *opaque);
    void *change_opaque;
42
43
44
45
46
47

    uint8_t *cow_bitmap; /* if non NULL, COW mappings are used first */
    uint8_t *cow_bitmap_addr; /* mmap address of cow_bitmap */
    int cow_bitmap_size;
    int cow_fd;
    int64_t cow_sectors_offset;
bellard's avatar
bellard committed
48
49
50
    int boot_sector_enabled;
    uint8_t boot_sector_data[512];

51
    char filename[1024];
bellard's avatar
bellard committed
52
53
54
55
56
57
58
    
    /* NOTE: the following infos are only hints for real hardware
       drivers. They are not used by the block driver */
    int cyls, heads, secs;
    int type;
    char device_name[32];
    BlockDriverState *next;
bellard's avatar
bellard committed
59
60
};

bellard's avatar
bellard committed
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
static BlockDriverState *bdrv_first;

/* create a new block device (by default it is empty) */
BlockDriverState *bdrv_new(const char *device_name)
{
    BlockDriverState **pbs, *bs;

    bs = qemu_mallocz(sizeof(BlockDriverState));
    if(!bs)
        return NULL;
    pstrcpy(bs->device_name, sizeof(bs->device_name), device_name);
    /* insert at the end */
    pbs = &bdrv_first;
    while (*pbs != NULL)
        pbs = &(*pbs)->next;
    *pbs = bs;
    return bs;
}

int bdrv_open(BlockDriverState *bs, const char *filename, int snapshot)
bellard's avatar
bellard committed
81
{
bellard's avatar
bellard committed
82
    int fd;
bellard's avatar
bellard committed
83
    int64_t size;
84
    struct cow_header_v2 cow_header;
bellard's avatar
bellard committed
85
86
87
#ifndef _WIN32
    char template[] = "/tmp/vl.XXXXXX";
    int cow_fd;
88
    struct stat st;
bellard's avatar
bellard committed
89
#endif
bellard's avatar
bellard committed
90

bellard's avatar
bellard committed
91
    bs->read_only = 0;
92
93
94
    bs->fd = -1;
    bs->cow_fd = -1;
    bs->cow_bitmap = NULL;
bellard's avatar
bellard committed
95
    pstrcpy(bs->filename, sizeof(bs->filename), filename);
96
97

    /* open standard HD image */
bellard's avatar
bellard committed
98
99
100
#ifdef _WIN32
    fd = open(filename, O_RDWR | O_BINARY);
#else
101
    fd = open(filename, O_RDWR | O_LARGEFILE);
bellard's avatar
bellard committed
102
#endif
bellard's avatar
bellard committed
103
    if (fd < 0) {
104
        /* read only image on disk */
bellard's avatar
bellard committed
105
106
107
#ifdef _WIN32
        fd = open(filename, O_RDONLY | O_BINARY);
#else
108
        fd = open(filename, O_RDONLY | O_LARGEFILE);
bellard's avatar
bellard committed
109
#endif
bellard's avatar
bellard committed
110
        if (fd < 0) {
111
112
            perror(filename);
            goto fail;
bellard's avatar
bellard committed
113
        }
114
115
        if (!snapshot)
            bs->read_only = 1;
bellard's avatar
bellard committed
116
117
    }
    bs->fd = fd;
118
119
120
121
122
123

    /* see if it is a cow image */
    if (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) {
        fprintf(stderr, "%s: could not read header\n", filename);
        goto fail;
    }
bellard's avatar
bellard committed
124
125
126
#ifndef _WIN32
    if (be32_to_cpu(cow_header.magic) == COW_MAGIC &&
        be32_to_cpu(cow_header.version) == COW_VERSION) {
127
128
129
130
131
132
133
134
135
136
137
138
139
140
        /* cow image found */
        size = cow_header.size;
#ifndef WORDS_BIGENDIAN
        size = bswap64(size);
#endif    
        bs->total_sectors = size / 512;

        bs->cow_fd = fd;
        bs->fd = -1;
        if (cow_header.backing_file[0] != '\0') {
            if (stat(cow_header.backing_file, &st) != 0) {
                fprintf(stderr, "%s: could not find original disk image '%s'\n", filename, cow_header.backing_file);
                goto fail;
            }
bellard's avatar
bellard committed
141
            if (st.st_mtime != be32_to_cpu(cow_header.mtime)) {
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
                fprintf(stderr, "%s: original raw disk image '%s' does not match saved timestamp\n", filename, cow_header.backing_file);
                goto fail;
            }
            fd = open(cow_header.backing_file, O_RDONLY | O_LARGEFILE);
            if (fd < 0)
                goto fail;
            bs->fd = fd;
        }
        /* mmap the bitmap */
        bs->cow_bitmap_size = ((bs->total_sectors + 7) >> 3) + sizeof(cow_header);
        bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size), 
                                   bs->cow_bitmap_size, 
                                   PROT_READ | PROT_WRITE,
                                   MAP_SHARED, bs->cow_fd, 0);
        if (bs->cow_bitmap_addr == MAP_FAILED)
            goto fail;
        bs->cow_bitmap = bs->cow_bitmap_addr + sizeof(cow_header);
        bs->cow_sectors_offset = (bs->cow_bitmap_size + 511) & ~511;
        snapshot = 0;
bellard's avatar
bellard committed
161
162
163
    } else 
#endif
    {
164
165
166
167
168
169
        /* standard raw image */
        size = lseek64(fd, 0, SEEK_END);
        bs->total_sectors = size / 512;
        bs->fd = fd;
    }

bellard's avatar
bellard committed
170
#ifndef _WIN32
171
172
    if (snapshot) {
        /* create a temporary COW file */
bellard's avatar
bellard committed
173
        cow_fd = mkstemp64(template);
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
        if (cow_fd < 0)
            goto fail;
        bs->cow_fd = cow_fd;
	unlink(template);
        
        /* just need to allocate bitmap */
        bs->cow_bitmap_size = (bs->total_sectors + 7) >> 3;
        bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size), 
                                   bs->cow_bitmap_size, 
                                   PROT_READ | PROT_WRITE,
                                   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
        if (bs->cow_bitmap_addr == MAP_FAILED)
            goto fail;
        bs->cow_bitmap = bs->cow_bitmap_addr;
        bs->cow_sectors_offset = 0;
    }
bellard's avatar
bellard committed
190
#endif
191
    
bellard's avatar
bellard committed
192
193
194
195
196
197
198
    bs->inserted = 1;

    /* call the change callback */
    if (bs->change_cb)
        bs->change_cb(bs->change_opaque);

    return 0;
199
200
 fail:
    bdrv_close(bs);
bellard's avatar
bellard committed
201
    return -1;
bellard's avatar
bellard committed
202
203
204
205
}

void bdrv_close(BlockDriverState *bs)
{
bellard's avatar
bellard committed
206
    if (bs->inserted) {
bellard's avatar
bellard committed
207
#ifndef _WIN32
bellard's avatar
bellard committed
208
209
210
        /* we unmap the mapping so that it is written to the COW file */
        if (bs->cow_bitmap_addr)
            munmap(bs->cow_bitmap_addr, bs->cow_bitmap_size);
bellard's avatar
bellard committed
211
#endif
bellard's avatar
bellard committed
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
        if (bs->cow_fd >= 0)
            close(bs->cow_fd);
        if (bs->fd >= 0)
            close(bs->fd);
        bs->inserted = 0;

        /* call the change callback */
        if (bs->change_cb)
            bs->change_cb(bs->change_opaque);
    }
}

void bdrv_delete(BlockDriverState *bs)
{
    bdrv_close(bs);
    qemu_free(bs);
bellard's avatar
bellard committed
228
229
}

230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
static inline void set_bit(uint8_t *bitmap, int64_t bitnum)
{
    bitmap[bitnum / 8] |= (1 << (bitnum%8));
}

static inline int is_bit_set(const uint8_t *bitmap, int64_t bitnum)
{
    return !!(bitmap[bitnum / 8] & (1 << (bitnum%8)));
}


/* Return true if first block has been changed (ie. current version is
 * in COW file).  Set the number of continuous blocks for which that
 * is true. */
static int is_changed(uint8_t *bitmap,
                      int64_t sector_num, int nb_sectors,
                      int *num_same)
{
    int changed;

    if (!bitmap || nb_sectors == 0) {
	*num_same = nb_sectors;
	return 0;
    }

    changed = is_bit_set(bitmap, sector_num);
    for (*num_same = 1; *num_same < nb_sectors; (*num_same)++) {
	if (is_bit_set(bitmap, sector_num + *num_same) != changed)
	    break;
    }

    return changed;
}

/* commit COW file into the raw image */
int bdrv_commit(BlockDriverState *bs)
{
    int64_t i;
    uint8_t *cow_bitmap;

bellard's avatar
bellard committed
270
271
272
    if (!bs->inserted)
        return -1;

273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
    if (!bs->cow_bitmap) {
	fprintf(stderr, "Already committed to %s\n", bs->filename);
	return 0;
    }

    if (bs->read_only) {
	fprintf(stderr, "Can't commit to %s: read-only\n", bs->filename);
	return -1;
    }

    cow_bitmap = bs->cow_bitmap;
    for (i = 0; i < bs->total_sectors; i++) {
	if (is_bit_set(cow_bitmap, i)) {
	    unsigned char sector[512];
	    if (bdrv_read(bs, i, sector, 1) != 0) {
		fprintf(stderr, "Error reading sector %lli: aborting commit\n",
			(long long)i);
		return -1;
	    }

	    /* Make bdrv_write write to real file for a moment. */
	    bs->cow_bitmap = NULL;
	    if (bdrv_write(bs, i, sector, 1) != 0) {
		fprintf(stderr, "Error writing sector %lli: aborting commit\n",
			(long long)i);
		bs->cow_bitmap = cow_bitmap;
		return -1;
	    }
	    bs->cow_bitmap = cow_bitmap;
	}
    }
    fprintf(stderr, "Committed snapshot to %s\n", bs->filename);
    return 0;
}

bellard's avatar
bellard committed
308
309
310
311
/* return -1 if error */
int bdrv_read(BlockDriverState *bs, int64_t sector_num, 
              uint8_t *buf, int nb_sectors)
{
312
313
314
    int ret, n, fd;
    int64_t offset;
    
bellard's avatar
bellard committed
315
316
317
    if (!bs->inserted)
        return -1;

318
319
320
321
    while (nb_sectors > 0) {
        if (is_changed(bs->cow_bitmap, sector_num, nb_sectors, &n)) {
            fd = bs->cow_fd;
            offset = bs->cow_sectors_offset;
bellard's avatar
bellard committed
322
323
324
325
        } else if (sector_num == 0 && bs->boot_sector_enabled) {
            memcpy(buf, bs->boot_sector_data, 512);
            n = 1;
            goto next;
326
327
328
329
        } else {
            fd = bs->fd;
            offset = 0;
        }
bellard's avatar
bellard committed
330

331
332
333
334
335
336
337
338
339
340
341
        if (fd < 0) {
            /* no file, just return empty sectors */
            memset(buf, 0, n * 512);
        } else {
            offset += sector_num * 512;
            lseek64(fd, offset, SEEK_SET);
            ret = read(fd, buf, n * 512);
            if (ret != n * 512) {
                return -1;
            }
        }
bellard's avatar
bellard committed
342
    next:
343
344
345
346
347
        nb_sectors -= n;
        sector_num += n;
        buf += n * 512;
    }
    return 0;
bellard's avatar
bellard committed
348
349
350
351
352
353
}

/* return -1 if error */
int bdrv_write(BlockDriverState *bs, int64_t sector_num, 
               const uint8_t *buf, int nb_sectors)
{
354
355
    int ret, fd, i;
    int64_t offset, retl;
bellard's avatar
bellard committed
356
    
bellard's avatar
bellard committed
357
358
    if (!bs->inserted)
        return -1;
bellard's avatar
bellard committed
359
360
361
    if (bs->read_only)
        return -1;

362
363
364
365
366
367
368
369
370
371
372
    if (bs->cow_bitmap) {
        fd = bs->cow_fd;
        offset = bs->cow_sectors_offset;
    } else {
        fd = bs->fd;
        offset = 0;
    }
    
    offset += sector_num * 512;
    retl = lseek64(fd, offset, SEEK_SET);
    if (retl == -1) {
bellard's avatar
bellard committed
373
        return -1;
374
375
376
377
378
379
380
381
382
383
384
    }
    ret = write(fd, buf, nb_sectors * 512);
    if (ret != nb_sectors * 512) {
        return -1;
    }

    if (bs->cow_bitmap) {
	for (i = 0; i < nb_sectors; i++)
	    set_bit(bs->cow_bitmap, sector_num + i);
    }
    return 0;
bellard's avatar
bellard committed
385
386
387
388
389
390
}

void bdrv_get_geometry(BlockDriverState *bs, int64_t *nb_sectors_ptr)
{
    *nb_sectors_ptr = bs->total_sectors;
}
bellard's avatar
bellard committed
391
392
393
394
395
396
397
398
399
400

/* force a given boot sector. */
void bdrv_set_boot_sector(BlockDriverState *bs, const uint8_t *data, int size)
{
    bs->boot_sector_enabled = 1;
    if (size > 512)
        size = 512;
    memcpy(bs->boot_sector_data, data, size);
    memset(bs->boot_sector_data + size, 0, 512 - size);
}
bellard's avatar
bellard committed
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503

void bdrv_set_geometry_hint(BlockDriverState *bs, 
                            int cyls, int heads, int secs)
{
    bs->cyls = cyls;
    bs->heads = heads;
    bs->secs = secs;
}

void bdrv_set_type_hint(BlockDriverState *bs, int type)
{
    bs->type = type;
    bs->removable = ((type == BDRV_TYPE_CDROM ||
                      type == BDRV_TYPE_FLOPPY));
}

void bdrv_get_geometry_hint(BlockDriverState *bs, 
                            int *pcyls, int *pheads, int *psecs)
{
    *pcyls = bs->cyls;
    *pheads = bs->heads;
    *psecs = bs->secs;
}

int bdrv_get_type_hint(BlockDriverState *bs)
{
    return bs->type;
}

int bdrv_is_removable(BlockDriverState *bs)
{
    return bs->removable;
}

int bdrv_is_read_only(BlockDriverState *bs)
{
    return bs->read_only;
}

int bdrv_is_inserted(BlockDriverState *bs)
{
    return bs->inserted;
}

int bdrv_is_locked(BlockDriverState *bs)
{
    return bs->locked;
}

void bdrv_set_locked(BlockDriverState *bs, int locked)
{
    bs->locked = locked;
}

void bdrv_set_change_cb(BlockDriverState *bs, 
                        void (*change_cb)(void *opaque), void *opaque)
{
    bs->change_cb = change_cb;
    bs->change_opaque = opaque;
}

BlockDriverState *bdrv_find(const char *name)
{
    BlockDriverState *bs;

    for (bs = bdrv_first; bs != NULL; bs = bs->next) {
        if (!strcmp(name, bs->device_name))
            return bs;
    }
    return NULL;
}

void bdrv_info(void)
{
    BlockDriverState *bs;

    for (bs = bdrv_first; bs != NULL; bs = bs->next) {
        term_printf("%s:", bs->device_name);
        term_printf(" type=");
        switch(bs->type) {
        case BDRV_TYPE_HD:
            term_printf("hd");
            break;
        case BDRV_TYPE_CDROM:
            term_printf("cdrom");
            break;
        case BDRV_TYPE_FLOPPY:
            term_printf("floppy");
            break;
        }
        term_printf(" removable=%d", bs->removable);
        if (bs->removable) {
            term_printf(" locked=%d", bs->locked);
        }
        if (bs->inserted) {
            term_printf(" file=%s", bs->filename);
            term_printf(" ro=%d", bs->read_only);
        } else {
            term_printf(" [not inserted]");
        }
        term_printf("\n");
    }
}