[qemu.git] / block.c

/*
 * 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 <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <getopt.h>
#include <inttypes.h>
#include <unistd.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <signal.h>
#include <time.h>
#include <sys/time.h>
#include <malloc.h>
#include <termios.h>
#include <sys/poll.h>
#include <errno.h>
#include <sys/wait.h>
#include <netinet/in.h>

#include "vl.h"

#define NO_THUNK_TYPE_SIZE
#include "thunk.h"

#include "cow.h"

struct BlockDriverState {
    int fd; /* if -1, only COW mappings */
    int64_t total_sectors;
    int read_only;

    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;
    int boot_sector_enabled;
    uint8_t boot_sector_data[512];

    char filename[1024];
};

BlockDriverState *bdrv_open(const char *filename, int snapshot)
{
    BlockDriverState *bs;
    int fd, cow_fd;
    int64_t size;
    char template[] = "/tmp/vl.XXXXXX";
    struct cow_header_v2 cow_header;
    struct stat st;

    bs = malloc(sizeof(BlockDriverState));
    if(!bs)
        return NULL;
    bs->read_only = 0;
    bs->fd = -1;
    bs->cow_fd = -1;
    bs->cow_bitmap = NULL;
    strcpy(bs->filename, filename);

    /* open standard HD image */
    fd = open(filename, O_RDWR | O_LARGEFILE);
    if (fd < 0) {
        /* read only image on disk */
        fd = open(filename, O_RDONLY | O_LARGEFILE);
        if (fd < 0) {
            perror(filename);
            goto fail;
        }
        if (!snapshot)
            bs->read_only = 1;
    }
    bs->fd = fd;

    /* 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;
    }
    if (cow_header.magic == htonl(COW_MAGIC) &&
        cow_header.version == htonl(COW_VERSION)) {
        /* 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;
            }
            if (st.st_mtime != htonl(cow_header.mtime)) {
                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;
    } else {
        /* standard raw image */
        size = lseek64(fd, 0, SEEK_END);
        bs->total_sectors = size / 512;
        bs->fd = fd;
    }

    if (snapshot) {
        /* create a temporary COW file */
        cow_fd = mkstemp(template);
        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;
    }
    
    return bs;
 fail:
    bdrv_close(bs);
    return NULL;
}

void bdrv_close(BlockDriverState *bs)
{
    /* 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);
    if (bs->cow_fd >= 0)
        close(bs->cow_fd);
    if (bs->fd >= 0)
        close(bs->fd);
    free(bs);
}

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;

    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;
}

/* return -1 if error */
int bdrv_read(BlockDriverState *bs, int64_t sector_num, 
              uint8_t *buf, int nb_sectors)
{
    int ret, n, fd;
    int64_t offset;
    
    while (nb_sectors > 0) {
        if (is_changed(bs->cow_bitmap, sector_num, nb_sectors, &n)) {
            fd = bs->cow_fd;
            offset = bs->cow_sectors_offset;
        } else if (sector_num == 0 && bs->boot_sector_enabled) {
            memcpy(buf, bs->boot_sector_data, 512);
            n = 1;
            goto next;
        } else {
            fd = bs->fd;
            offset = 0;
        }

        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;
            }
        }
    next:
        nb_sectors -= n;
        sector_num += n;
        buf += n * 512;
    }
    return 0;
}

/* return -1 if error */
int bdrv_write(BlockDriverState *bs, int64_t sector_num, 
               const uint8_t *buf, int nb_sectors)
{
    int ret, fd, i;
    int64_t offset, retl;
    
    if (bs->read_only)
        return -1;

    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) {
        return -1;
    }
    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;
}

void bdrv_get_geometry(BlockDriverState *bs, int64_t *nb_sectors_ptr)
{
    *nb_sectors_ptr = bs->total_sectors;
}

/* 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);
}
Commit	Line	Data
fc01f7e7 FB	1	/*
	2	* QEMU System Emulator block driver
	3	*
	4	* Copyright (c) 2003 Fabrice Bellard
	5	*
	6	* Permission is hereby granted, free of charge, to any person obtaining a copy
	7	* of this software and associated documentation files (the "Software"), to deal
	8	* in the Software without restriction, including without limitation the rights
	9	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	10	* copies of the Software, and to permit persons to whom the Software is
	11	* furnished to do so, subject to the following conditions:
	12	*
	13	* The above copyright notice and this permission notice shall be included in
	14	* all copies or substantial portions of the Software.
	15	*
	16	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	17	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	18	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	19	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	20	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	21	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	22	* THE SOFTWARE.
	23	*/
	24	#include <stdlib.h>
	25	#include <stdio.h>
	26	#include <stdarg.h>
	27	#include <string.h>
	28	#include <getopt.h>
	29	#include <inttypes.h>
	30	#include <unistd.h>
	31	#include <sys/mman.h>
	32	#include <fcntl.h>
	33	#include <signal.h>
	34	#include <time.h>
	35	#include <sys/time.h>
	36	#include <malloc.h>
	37	#include <termios.h>
	38	#include <sys/poll.h>
	39	#include <errno.h>
	40	#include <sys/wait.h>
33e3963e	41	#include <netinet/in.h>
fc01f7e7 FB	42
	43	#include "vl.h"
	44
33e3963e FB	45	#define NO_THUNK_TYPE_SIZE
	46	#include "thunk.h"
	47
00af2b26 FB	48	#include "cow.h"
00af2b26 FB	49
fc01f7e7	50	struct BlockDriverState {
33e3963e	51	int fd; /* if -1, only COW mappings */
fc01f7e7	52	int64_t total_sectors;
0849bf08	53	int read_only;
33e3963e FB	54
	55	uint8_t cow_bitmap; / if non NULL, COW mappings are used first */
	56	uint8_t cow_bitmap_addr; / mmap address of cow_bitmap */
	57	int cow_bitmap_size;
	58	int cow_fd;
	59	int64_t cow_sectors_offset;
cf98951b FB	60	int boot_sector_enabled;
	61	uint8_t boot_sector_data[512];
	62
33e3963e	63	char filename[1024];
fc01f7e7 FB	64	};
fc01f7e7 FB	65
33e3963e	66	BlockDriverState bdrv_open(const char filename, int snapshot)
fc01f7e7 FB	67	{
fc01f7e7 FB	68	BlockDriverState *bs;
33e3963e	69	int fd, cow_fd;
fc01f7e7	70	int64_t size;
33e3963e FB	71	char template[] = "/tmp/vl.XXXXXX";
	72	struct cow_header_v2 cow_header;
	73	struct stat st;
fc01f7e7 FB	74
	75	bs = malloc(sizeof(BlockDriverState));
	76	if(!bs)
	77	return NULL;
0849bf08	78	bs->read_only = 0;
33e3963e FB	79	bs->fd = -1;
	80	bs->cow_fd = -1;
	81	bs->cow_bitmap = NULL;
	82	strcpy(bs->filename, filename);
	83
	84	/* open standard HD image */
	85	fd = open(filename, O_RDWR \| O_LARGEFILE);
fc01f7e7	86	if (fd < 0) {
33e3963e FB	87	/* read only image on disk */
33e3963e FB	88	fd = open(filename, O_RDONLY \| O_LARGEFILE);
0849bf08	89	if (fd < 0) {
33e3963e FB	90	perror(filename);
33e3963e FB	91	goto fail;
0849bf08	92	}
33e3963e FB	93	if (!snapshot)
33e3963e FB	94	bs->read_only = 1;
fc01f7e7	95	}
fc01f7e7	96	bs->fd = fd;
33e3963e FB	97
	98	/* see if it is a cow image */
	99	if (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) {
	100	fprintf(stderr, "%s: could not read header\n", filename);
	101	goto fail;
	102	}
	103	if (cow_header.magic == htonl(COW_MAGIC) &&
	104	cow_header.version == htonl(COW_VERSION)) {
	105	/* cow image found */
	106	size = cow_header.size;
	107	#ifndef WORDS_BIGENDIAN
	108	size = bswap64(size);
	109	#endif
	110	bs->total_sectors = size / 512;
	111
	112	bs->cow_fd = fd;
	113	bs->fd = -1;
	114	if (cow_header.backing_file[0] != '\0') {
	115	if (stat(cow_header.backing_file, &st) != 0) {
	116	fprintf(stderr, "%s: could not find original disk image '%s'\n", filename, cow_header.backing_file);
	117	goto fail;
	118	}
	119	if (st.st_mtime != htonl(cow_header.mtime)) {
	120	fprintf(stderr, "%s: original raw disk image '%s' does not match saved timestamp\n", filename, cow_header.backing_file);
	121	goto fail;
	122	}
	123	fd = open(cow_header.backing_file, O_RDONLY \| O_LARGEFILE);
	124	if (fd < 0)
	125	goto fail;
	126	bs->fd = fd;
	127	}
	128	/* mmap the bitmap */
	129	bs->cow_bitmap_size = ((bs->total_sectors + 7) >> 3) + sizeof(cow_header);
	130	bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size),
	131	bs->cow_bitmap_size,
	132	PROT_READ \| PROT_WRITE,
	133	MAP_SHARED, bs->cow_fd, 0);
	134	if (bs->cow_bitmap_addr == MAP_FAILED)
	135	goto fail;
	136	bs->cow_bitmap = bs->cow_bitmap_addr + sizeof(cow_header);
	137	bs->cow_sectors_offset = (bs->cow_bitmap_size + 511) & ~511;
	138	snapshot = 0;
	139	} else {
	140	/* standard raw image */
	141	size = lseek64(fd, 0, SEEK_END);
	142	bs->total_sectors = size / 512;
	143	bs->fd = fd;
	144	}
	145
	146	if (snapshot) {
	147	/* create a temporary COW file */
	148	cow_fd = mkstemp(template);
	149	if (cow_fd < 0)
	150	goto fail;
	151	bs->cow_fd = cow_fd;
	152	unlink(template);
	153
	154	/* just need to allocate bitmap */
	155	bs->cow_bitmap_size = (bs->total_sectors + 7) >> 3;
	156	bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size),
	157	bs->cow_bitmap_size,
	158	PROT_READ \| PROT_WRITE,
	159	MAP_PRIVATE \| MAP_ANONYMOUS, -1, 0);
	160	if (bs->cow_bitmap_addr == MAP_FAILED)
161	goto fail;
162	bs->cow_bitmap = bs->cow_bitmap_addr;
163	bs->cow_sectors_offset = 0;
164	}
165
fc01f7e7	166	return bs;
33e3963e FB	167	fail:
	168	bdrv_close(bs);
	169	return NULL;
fc01f7e7 FB	170	}
	171
	172	void bdrv_close(BlockDriverState *bs)
	173	{
33e3963e FB	174	/* we unmap the mapping so that it is written to the COW file */
	175	if (bs->cow_bitmap_addr)
	176	munmap(bs->cow_bitmap_addr, bs->cow_bitmap_size);
	177	if (bs->cow_fd >= 0)
	178	close(bs->cow_fd);
	179	if (bs->fd >= 0)
	180	close(bs->fd);
fc01f7e7 FB	181	free(bs);
	182	}
	183
33e3963e FB	184	static inline void set_bit(uint8_t *bitmap, int64_t bitnum)
	185	{
	186	bitmap[bitnum / 8] \|= (1 << (bitnum%8));
	187	}
	188
	189	static inline int is_bit_set(const uint8_t *bitmap, int64_t bitnum)
	190	{
	191	return !!(bitmap[bitnum / 8] & (1 << (bitnum%8)));
	192	}
	193
	194
	195	/* Return true if first block has been changed (ie. current version is
	196	* in COW file). Set the number of continuous blocks for which that
	197	* is true. */
	198	static int is_changed(uint8_t *bitmap,
	199	int64_t sector_num, int nb_sectors,
	200	int *num_same)
	201	{
	202	int changed;
	203
	204	if (!bitmap \|\| nb_sectors == 0) {
	205	*num_same = nb_sectors;
	206	return 0;
	207	}
	208
	209	changed = is_bit_set(bitmap, sector_num);
	210	for (num_same = 1; num_same < nb_sectors; (*num_same)++) {
	211	if (is_bit_set(bitmap, sector_num + *num_same) != changed)
	212	break;
	213	}
	214
	215	return changed;
	216	}
	217
	218	/* commit COW file into the raw image */
	219	int bdrv_commit(BlockDriverState *bs)
	220	{
	221	int64_t i;
	222	uint8_t *cow_bitmap;
	223
	224	if (!bs->cow_bitmap) {
	225	fprintf(stderr, "Already committed to %s\n", bs->filename);
	226	return 0;
	227	}
	228
	229	if (bs->read_only) {
	230	fprintf(stderr, "Can't commit to %s: read-only\n", bs->filename);
	231	return -1;
	232	}
	233
	234	cow_bitmap = bs->cow_bitmap;
	235	for (i = 0; i < bs->total_sectors; i++) {
	236	if (is_bit_set(cow_bitmap, i)) {
	237	unsigned char sector[512];
	238	if (bdrv_read(bs, i, sector, 1) != 0) {
	239	fprintf(stderr, "Error reading sector %lli: aborting commit\n",
	240	(long long)i);
	241	return -1;
	242	}
	243
	244	/* Make bdrv_write write to real file for a moment. */
	245	bs->cow_bitmap = NULL;
	246	if (bdrv_write(bs, i, sector, 1) != 0) {
	247	fprintf(stderr, "Error writing sector %lli: aborting commit\n",
248	(long long)i);
249	bs->cow_bitmap = cow_bitmap;
250	return -1;
251	}
252	bs->cow_bitmap = cow_bitmap;
253	}
254	}
255	fprintf(stderr, "Committed snapshot to %s\n", bs->filename);
256	return 0;
257	}
258
fc01f7e7 FB	259	/* return -1 if error */
	260	int bdrv_read(BlockDriverState *bs, int64_t sector_num,
	261	uint8_t *buf, int nb_sectors)
	262	{
33e3963e FB	263	int ret, n, fd;
	264	int64_t offset;
	265
	266	while (nb_sectors > 0) {
	267	if (is_changed(bs->cow_bitmap, sector_num, nb_sectors, &n)) {
	268	fd = bs->cow_fd;
	269	offset = bs->cow_sectors_offset;
cf98951b FB	270	} else if (sector_num == 0 && bs->boot_sector_enabled) {
	271	memcpy(buf, bs->boot_sector_data, 512);
	272	n = 1;
	273	goto next;
33e3963e FB	274	} else {
	275	fd = bs->fd;
	276	offset = 0;
	277	}
fc01f7e7	278
33e3963e FB	279	if (fd < 0) {
	280	/* no file, just return empty sectors */
	281	memset(buf, 0, n * 512);
	282	} else {
	283	offset += sector_num * 512;
	284	lseek64(fd, offset, SEEK_SET);
	285	ret = read(fd, buf, n * 512);
	286	if (ret != n * 512) {
	287	return -1;
	288	}
	289	}
cf98951b	290	next:
33e3963e FB	291	nb_sectors -= n;
	292	sector_num += n;
	293	buf += n * 512;
	294	}
	295	return 0;
fc01f7e7 FB	296	}
	297
	298	/* return -1 if error */
	299	int bdrv_write(BlockDriverState *bs, int64_t sector_num,
	300	const uint8_t *buf, int nb_sectors)
	301	{
33e3963e FB	302	int ret, fd, i;
33e3963e FB	303	int64_t offset, retl;
cf98951b	304
0849bf08 FB	305	if (bs->read_only)
	306	return -1;
	307
33e3963e FB	308	if (bs->cow_bitmap) {
	309	fd = bs->cow_fd;
	310	offset = bs->cow_sectors_offset;
	311	} else {
	312	fd = bs->fd;
	313	offset = 0;
	314	}
	315
	316	offset += sector_num * 512;
	317	retl = lseek64(fd, offset, SEEK_SET);
	318	if (retl == -1) {
fc01f7e7	319	return -1;
33e3963e FB	320	}
	321	ret = write(fd, buf, nb_sectors * 512);
	322	if (ret != nb_sectors * 512) {
	323	return -1;
	324	}
	325
	326	if (bs->cow_bitmap) {
	327	for (i = 0; i < nb_sectors; i++)
	328	set_bit(bs->cow_bitmap, sector_num + i);
	329	}
	330	return 0;
fc01f7e7 FB	331	}
	332
	333	void bdrv_get_geometry(BlockDriverState bs, int64_t nb_sectors_ptr)
	334	{
	335	*nb_sectors_ptr = bs->total_sectors;
	336	}
cf98951b FB	337
	338	/* force a given boot sector. */
	339	void bdrv_set_boot_sector(BlockDriverState bs, const uint8_t data, int size)
	340	{
	341	bs->boot_sector_enabled = 1;
	342	if (size > 512)
	343	size = 512;
	344	memcpy(bs->boot_sector_data, data, size);
	345	memset(bs->boot_sector_data + size, 0, 512 - size);
	346	}