block.c - qemu - Git at Google

 /*
  * 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"
 #include "block_int.h"

 static BlockDriverState *bdrv_first;
 static BlockDriver *first_drv;

 void bdrv_register(BlockDriver *bdrv)
 {
     bdrv->next = first_drv;
     first_drv = bdrv;
 }

 /* 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);
     if (device_name[0] != '\0') {
         /* insert at the end */
         pbs = &bdrv_first;
         while (*pbs != NULL)
             pbs = &(*pbs)->next;
         *pbs = bs;
     }
     return bs;
 }

 BlockDriver *bdrv_find_format(const char *format_name)
 {
     BlockDriver *drv1;
     for(drv1 = first_drv; drv1 != NULL; drv1 = drv1->next) {
         if (!strcmp(drv1->format_name, format_name))
             return drv1;
     }
     return NULL;
 }

 int bdrv_create(BlockDriver *drv,
                 const char *filename, int64_t size_in_sectors,
                 const char *backing_file, int flags)
 {
     if (!drv->bdrv_create)
         return -ENOTSUP;
     return drv->bdrv_create(filename, size_in_sectors, backing_file, flags);
 }

 #ifdef _WIN32
 static void get_tmp_filename(char *filename, int size)
 {
     /* XXX: find a better function */
     tmpnam(filename);
 }
 #else
 static void get_tmp_filename(char *filename, int size)
 {
     int fd;
     /* XXX: race condition possible */
     pstrcpy(filename, size, "/tmp/vl.XXXXXX");
     fd = mkstemp(filename);
     close(fd);
 }
 #endif

 static BlockDriver *find_image_format(const char *filename)
 {
     int fd, ret, score, score_max;
     BlockDriver *drv1, *drv;
     uint8_t buf[1024];

     fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
     if (fd < 0)
         return NULL;
     ret = read(fd, buf, sizeof(buf));
     if (ret < 0) {
         close(fd);
         return NULL;
     }
     close(fd);

     drv = NULL;
     score_max = 0;
     for(drv1 = first_drv; drv1 != NULL; drv1 = drv1->next) {
         score = drv1->bdrv_probe(buf, ret, filename);
         if (score > score_max) {
             score_max = score;
             drv = drv1;
         }
     }
     return drv;
 }

 int bdrv_open(BlockDriverState *bs, const char *filename, int snapshot)
 {
     return bdrv_open2(bs, filename, snapshot, NULL);
 }

 int bdrv_open2(BlockDriverState *bs, const char *filename, int snapshot,
                BlockDriver *drv)
 {
     int ret;
     char tmp_filename[1024];

     bs->read_only = 0;
     bs->is_temporary = 0;
     bs->encrypted = 0;

     if (snapshot) {
         BlockDriverState *bs1;
         int64_t total_size;

         /* if snapshot, we create a temporary backing file and open it
            instead of opening 'filename' directly */

         /* if there is a backing file, use it */
         bs1 = bdrv_new("");
         if (!bs1) {
             return -1;
         }
         if (bdrv_open(bs1, filename, 0) < 0) {
             bdrv_delete(bs1);
             return -1;
         }
         total_size = bs1->total_sectors;
         bdrv_delete(bs1);

         get_tmp_filename(tmp_filename, sizeof(tmp_filename));
         /* XXX: use cow for linux as it is more efficient ? */
         if (bdrv_create(&bdrv_qcow, tmp_filename,
                         total_size, filename, 0) < 0) {
             return -1;
         }
         filename = tmp_filename;
         bs->is_temporary = 1;
     }

     pstrcpy(bs->filename, sizeof(bs->filename), filename);
     if (!drv) {
         drv = find_image_format(filename);
         if (!drv)
             return -1;
     }
     bs->drv = drv;
     bs->opaque = qemu_mallocz(drv->instance_size);
     if (bs->opaque == NULL && drv->instance_size > 0)
         return -1;

     ret = drv->bdrv_open(bs, filename);
     if (ret < 0) {
         qemu_free(bs->opaque);
         return -1;
     }
 #ifndef _WIN32
     if (bs->is_temporary) {
         unlink(filename);
     }
 #endif
     if (bs->backing_file[0] != '\0' && drv->bdrv_is_allocated) {
         /* if there is a backing file, use it */
         bs->backing_hd = bdrv_new("");
         if (!bs->backing_hd) {
         fail:
             bdrv_close(bs);
             return -1;
         }
         if (bdrv_open(bs->backing_hd, bs->backing_file, 0) < 0)
             goto fail;
     }

     bs->inserted = 1;

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

     return 0;
 }

 void bdrv_close(BlockDriverState *bs)
 {
     if (bs->inserted) {
         if (bs->backing_hd)
             bdrv_delete(bs->backing_hd);
         bs->drv->bdrv_close(bs);
         qemu_free(bs->opaque);
 #ifdef _WIN32
         if (bs->is_temporary) {
             unlink(bs->filename);
         }
 #endif
         bs->opaque = NULL;
         bs->drv = NULL;
         bs->inserted = 0;

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

 void bdrv_delete(BlockDriverState *bs)
 {
     /* XXX: remove the driver list */
     bdrv_close(bs);
     qemu_free(bs);
 }

 /* commit COW file into the raw image */
 int bdrv_commit(BlockDriverState *bs)
 {
     int64_t i;
     int n, j;
     unsigned char sector[512];

     if (!bs->inserted)
         return -ENOENT;

     if (bs->read_only) {
 	return -EACCES;
     }

     if (!bs->backing_hd) {
 	return -ENOTSUP;
     }

     for (i = 0; i < bs->total_sectors;) {
         if (bs->drv->bdrv_is_allocated(bs, i, 65536, &n)) {
             for(j = 0; j < n; j++) {
                 if (bdrv_read(bs, i, sector, 1) != 0) {
                     return -EIO;
                 }

                 if (bdrv_write(bs->backing_hd, i, sector, 1) != 0) {
                     return -EIO;
                 }
                 i++;
 	    }
 	} else {
             i += n;
         }
     }
     return 0;
 }

 /* return -1 if error */
 int bdrv_read(BlockDriverState *bs, int64_t sector_num,
               uint8_t *buf, int nb_sectors)
 {
     int ret, n;
     BlockDriver *drv = bs->drv;

     if (!bs->inserted)
         return -1;

     while (nb_sectors > 0) {
         if (sector_num == 0 && bs->boot_sector_enabled) {
             memcpy(buf, bs->boot_sector_data, 512);
             n = 1;
         } else if (bs->backing_hd) {
             if (drv->bdrv_is_allocated(bs, sector_num, nb_sectors, &n)) {
                 ret = drv->bdrv_read(bs, sector_num, buf, n);
                 if (ret < 0)
                     return -1;
             } else {
                 /* read from the base image */
                 ret = bdrv_read(bs->backing_hd, sector_num, buf, n);
                 if (ret < 0)
                     return -1;
             }
         } else {
             ret = drv->bdrv_read(bs, sector_num, buf, nb_sectors);
             if (ret < 0)
                 return -1;
             /* no need to loop */
             break;
         }
         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)
 {
     if (!bs->inserted)
         return -1;
     if (bs->read_only)
         return -1;
     return bs->drv->bdrv_write(bs, sector_num, buf, nb_sectors);
 }

 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);
 }

 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;
 }

 int bdrv_is_encrypted(BlockDriverState *bs)
 {
     if (bs->backing_hd && bs->backing_hd->encrypted)
         return 1;
     return bs->encrypted;
 }

 int bdrv_set_key(BlockDriverState *bs, const char *key)
 {
     int ret;
     if (bs->backing_hd && bs->backing_hd->encrypted) {
         ret = bdrv_set_key(bs->backing_hd, key);
         if (ret < 0)
             return ret;
         if (!bs->encrypted)
             return 0;
     }
     if (!bs->encrypted || !bs->drv || !bs->drv->bdrv_set_key)
         return -1;
     return bs->drv->bdrv_set_key(bs, key);
 }

 void bdrv_get_format(BlockDriverState *bs, char *buf, int buf_size)
 {
     if (!bs->inserted || !bs->drv) {
         buf[0] = '\0';
     } else {
         pstrcpy(buf, buf_size, bs->drv->format_name);
     }
 }

 void bdrv_iterate_format(void (*it)(void *opaque, const char *name),
                          void *opaque)
 {
     BlockDriver *drv;

     for (drv = first_drv; drv != NULL; drv = drv->next) {
         it(opaque, drv->format_name);
     }
 }

 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_iterate(void (*it)(void *opaque, const char *name), void *opaque)
 {
     BlockDriverState *bs;

     for (bs = bdrv_first; bs != NULL; bs = bs->next) {
         it(opaque, bs->device_name);
     }
 }

 const char *bdrv_get_device_name(BlockDriverState *bs)
 {
     return bs->device_name;
 }

 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);
             if (bs->backing_file[0] != '\0')
                 term_printf(" backing_file=%s", bs->backing_file);
             term_printf(" ro=%d", bs->read_only);
             term_printf(" drv=%s", bs->drv->format_name);
             if (bs->encrypted)
                 term_printf(" encrypted");
         } else {
             term_printf(" [not inserted]");
         }
         term_printf("\n");
     }
 }


 /**************************************************************/
 /* RAW block driver */

 typedef struct BDRVRawState {
     int fd;
 } BDRVRawState;

 static int raw_probe(const uint8_t *buf, int buf_size, const char *filename)
 {
     return 1; /* maybe */
 }

 static int raw_open(BlockDriverState *bs, const char *filename)
 {
     BDRVRawState *s = bs->opaque;
     int fd;
     int64_t size;

     fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE);
     if (fd < 0) {
         fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
         if (fd < 0)
             return -1;
         bs->read_only = 1;
     }
     size = lseek(fd, 0, SEEK_END);
     bs->total_sectors = size / 512;
     s->fd = fd;
     return 0;
 }

 static int raw_read(BlockDriverState *bs, int64_t sector_num,
                     uint8_t *buf, int nb_sectors)
 {
     BDRVRawState *s = bs->opaque;
     int ret;

     lseek(s->fd, sector_num * 512, SEEK_SET);
     ret = read(s->fd, buf, nb_sectors * 512);
     if (ret != nb_sectors * 512)
         return -1;
     return 0;
 }

 static int raw_write(BlockDriverState *bs, int64_t sector_num,
                      const uint8_t *buf, int nb_sectors)
 {
     BDRVRawState *s = bs->opaque;
     int ret;

     lseek(s->fd, sector_num * 512, SEEK_SET);
     ret = write(s->fd, buf, nb_sectors * 512);
     if (ret != nb_sectors * 512)
         return -1;
     return 0;
 }

 static void raw_close(BlockDriverState *bs)
 {
     BDRVRawState *s = bs->opaque;
     close(s->fd);
 }

 static int raw_create(const char *filename, int64_t total_size,
                       const char *backing_file, int flags)
 {
     int fd;

     if (flags || backing_file)
         return -ENOTSUP;

     fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
               0644);
     if (fd < 0)
         return -EIO;
     ftruncate(fd, total_size * 512);
     close(fd);
     return 0;
 }

 BlockDriver bdrv_raw = {
     "raw",
     sizeof(BDRVRawState),
     raw_probe,
     raw_open,
     raw_read,
     raw_write,
     raw_close,
     raw_create,
 };

 void bdrv_init(void)
 {
     bdrv_register(&bdrv_raw);
 #ifndef _WIN32
     bdrv_register(&bdrv_cow);
 #endif
     bdrv_register(&bdrv_qcow);
     bdrv_register(&bdrv_vmdk);
     bdrv_register(&bdrv_cloop);
 }
	/*
	* 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"
	#include "block_int.h"

	static BlockDriverState *bdrv_first;
	static BlockDriver *first_drv;

	void bdrv_register(BlockDriver *bdrv)
	{
	bdrv->next = first_drv;
	first_drv = bdrv;
	}

	/* 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);
	if (device_name[0] != '\0') {
	/* insert at the end */
	pbs = &bdrv_first;
	while (*pbs != NULL)
	pbs = &(*pbs)->next;
	*pbs = bs;
	}
	return bs;
	}

	BlockDriver bdrv_find_format(const char format_name)
	{
	BlockDriver *drv1;
	for(drv1 = first_drv; drv1 != NULL; drv1 = drv1->next) {
	if (!strcmp(drv1->format_name, format_name))
	return drv1;
	}
	return NULL;
	}

	int bdrv_create(BlockDriver *drv,
	const char *filename, int64_t size_in_sectors,
	const char *backing_file, int flags)
	{
	if (!drv->bdrv_create)
	return -ENOTSUP;
	return drv->bdrv_create(filename, size_in_sectors, backing_file, flags);
	}

	#ifdef _WIN32
	static void get_tmp_filename(char *filename, int size)
	{
	/* XXX: find a better function */
	tmpnam(filename);
	}
	#else
	static void get_tmp_filename(char *filename, int size)
	{
	int fd;
	/* XXX: race condition possible */
	pstrcpy(filename, size, "/tmp/vl.XXXXXX");
	fd = mkstemp(filename);
	close(fd);
	}
	#endif

	static BlockDriver find_image_format(const char filename)
	{
	int fd, ret, score, score_max;
	BlockDriver drv1, drv;
	uint8_t buf[1024];

	fd = open(filename, O_RDONLY \| O_BINARY \| O_LARGEFILE);
	if (fd < 0)
	return NULL;
	ret = read(fd, buf, sizeof(buf));
	if (ret < 0) {
	close(fd);
	return NULL;
	}
	close(fd);

	drv = NULL;
	score_max = 0;
	for(drv1 = first_drv; drv1 != NULL; drv1 = drv1->next) {
	score = drv1->bdrv_probe(buf, ret, filename);
	if (score > score_max) {
	score_max = score;
	drv = drv1;
	}
	}
	return drv;
	}

	int bdrv_open(BlockDriverState bs, const char filename, int snapshot)
	{
	return bdrv_open2(bs, filename, snapshot, NULL);
	}

	int bdrv_open2(BlockDriverState bs, const char filename, int snapshot,
	BlockDriver *drv)
	{
	int ret;
	char tmp_filename[1024];

	bs->read_only = 0;
	bs->is_temporary = 0;
	bs->encrypted = 0;

	if (snapshot) {
	BlockDriverState *bs1;
	int64_t total_size;

	/* if snapshot, we create a temporary backing file and open it
	instead of opening 'filename' directly */

	/* if there is a backing file, use it */
	bs1 = bdrv_new("");
	if (!bs1) {
	return -1;
	}
	if (bdrv_open(bs1, filename, 0) < 0) {
	bdrv_delete(bs1);
	return -1;
	}
	total_size = bs1->total_sectors;
	bdrv_delete(bs1);

	get_tmp_filename(tmp_filename, sizeof(tmp_filename));
	/* XXX: use cow for linux as it is more efficient ? */
	if (bdrv_create(&bdrv_qcow, tmp_filename,
	total_size, filename, 0) < 0) {
	return -1;
	}
	filename = tmp_filename;
	bs->is_temporary = 1;
	}

	pstrcpy(bs->filename, sizeof(bs->filename), filename);
	if (!drv) {
	drv = find_image_format(filename);
	if (!drv)
	return -1;
	}
	bs->drv = drv;
	bs->opaque = qemu_mallocz(drv->instance_size);
	if (bs->opaque == NULL && drv->instance_size > 0)
	return -1;

	ret = drv->bdrv_open(bs, filename);
	if (ret < 0) {
	qemu_free(bs->opaque);
	return -1;
	}
	#ifndef _WIN32
	if (bs->is_temporary) {
	unlink(filename);
	}
	#endif
	if (bs->backing_file[0] != '\0' && drv->bdrv_is_allocated) {
	/* if there is a backing file, use it */
	bs->backing_hd = bdrv_new("");
	if (!bs->backing_hd) {
	fail:
	bdrv_close(bs);
	return -1;
	}
	if (bdrv_open(bs->backing_hd, bs->backing_file, 0) < 0)
	goto fail;
	}

	bs->inserted = 1;

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

	return 0;
	}

	void bdrv_close(BlockDriverState *bs)
	{
	if (bs->inserted) {
	if (bs->backing_hd)
	bdrv_delete(bs->backing_hd);
	bs->drv->bdrv_close(bs);
	qemu_free(bs->opaque);
	#ifdef _WIN32
	if (bs->is_temporary) {
	unlink(bs->filename);
	}
	#endif
	bs->opaque = NULL;
	bs->drv = NULL;
	bs->inserted = 0;

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

	void bdrv_delete(BlockDriverState *bs)
	{
	/* XXX: remove the driver list */
	bdrv_close(bs);
	qemu_free(bs);
	}

	/* commit COW file into the raw image */
	int bdrv_commit(BlockDriverState *bs)
	{
	int64_t i;
	int n, j;
	unsigned char sector[512];

	if (!bs->inserted)
	return -ENOENT;

	if (bs->read_only) {
	return -EACCES;
	}

	if (!bs->backing_hd) {
	return -ENOTSUP;
	}

	for (i = 0; i < bs->total_sectors;) {
	if (bs->drv->bdrv_is_allocated(bs, i, 65536, &n)) {
	for(j = 0; j < n; j++) {
	if (bdrv_read(bs, i, sector, 1) != 0) {
	return -EIO;
	}

	if (bdrv_write(bs->backing_hd, i, sector, 1) != 0) {
	return -EIO;
	}
	i++;
	}
	} else {
	i += n;
	}
	}
	return 0;
	}

	/* return -1 if error */
	int bdrv_read(BlockDriverState *bs, int64_t sector_num,
	uint8_t *buf, int nb_sectors)
	{
	int ret, n;
	BlockDriver *drv = bs->drv;

	if (!bs->inserted)
	return -1;

	while (nb_sectors > 0) {
	if (sector_num == 0 && bs->boot_sector_enabled) {
	memcpy(buf, bs->boot_sector_data, 512);
	n = 1;
	} else if (bs->backing_hd) {
	if (drv->bdrv_is_allocated(bs, sector_num, nb_sectors, &n)) {
	ret = drv->bdrv_read(bs, sector_num, buf, n);
	if (ret < 0)
	return -1;
	} else {
	/* read from the base image */
	ret = bdrv_read(bs->backing_hd, sector_num, buf, n);
	if (ret < 0)
	return -1;
	}
	} else {
	ret = drv->bdrv_read(bs, sector_num, buf, nb_sectors);
	if (ret < 0)
	return -1;
	/* no need to loop */
	break;
	}
	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)
	{
	if (!bs->inserted)
	return -1;
	if (bs->read_only)
	return -1;
	return bs->drv->bdrv_write(bs, sector_num, buf, nb_sectors);
	}

	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);
	}

	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;
	}

	int bdrv_is_encrypted(BlockDriverState *bs)
	{
	if (bs->backing_hd && bs->backing_hd->encrypted)
	return 1;
	return bs->encrypted;
	}

	int bdrv_set_key(BlockDriverState bs, const char key)
	{
	int ret;
	if (bs->backing_hd && bs->backing_hd->encrypted) {
	ret = bdrv_set_key(bs->backing_hd, key);
	if (ret < 0)
	return ret;
	if (!bs->encrypted)
	return 0;
	}
	if (!bs->encrypted \|\| !bs->drv \|\| !bs->drv->bdrv_set_key)
	return -1;
	return bs->drv->bdrv_set_key(bs, key);
	}

	void bdrv_get_format(BlockDriverState bs, char buf, int buf_size)
	{
	if (!bs->inserted \|\| !bs->drv) {
	buf[0] = '\0';
	} else {
	pstrcpy(buf, buf_size, bs->drv->format_name);
	}
	}

	void bdrv_iterate_format(void (it)(void opaque, const char *name),
	void *opaque)
	{
	BlockDriver *drv;

	for (drv = first_drv; drv != NULL; drv = drv->next) {
	it(opaque, drv->format_name);
	}
	}

	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_iterate(void (it)(void opaque, const char name), void opaque)
	{
	BlockDriverState *bs;

	for (bs = bdrv_first; bs != NULL; bs = bs->next) {
	it(opaque, bs->device_name);
	}
	}

	const char bdrv_get_device_name(BlockDriverState bs)
	{
	return bs->device_name;
	}

	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);
	if (bs->backing_file[0] != '\0')
	term_printf(" backing_file=%s", bs->backing_file);
	term_printf(" ro=%d", bs->read_only);
	term_printf(" drv=%s", bs->drv->format_name);
	if (bs->encrypted)
	term_printf(" encrypted");
	} else {
	term_printf(" [not inserted]");
	}
	term_printf("\n");
	}
	}


	/**************************************************************/
	/* RAW block driver */

	typedef struct BDRVRawState {
	int fd;
	} BDRVRawState;

	static int raw_probe(const uint8_t buf, int buf_size, const char filename)
	{
	return 1; /* maybe */
	}

	static int raw_open(BlockDriverState bs, const char filename)
	{
	BDRVRawState *s = bs->opaque;
	int fd;
	int64_t size;

	fd = open(filename, O_RDWR \| O_BINARY \| O_LARGEFILE);
	if (fd < 0) {
	fd = open(filename, O_RDONLY \| O_BINARY \| O_LARGEFILE);
	if (fd < 0)
	return -1;
	bs->read_only = 1;
	}
	size = lseek(fd, 0, SEEK_END);
	bs->total_sectors = size / 512;
	s->fd = fd;
	return 0;
	}

	static int raw_read(BlockDriverState *bs, int64_t sector_num,
	uint8_t *buf, int nb_sectors)
	{
	BDRVRawState *s = bs->opaque;
	int ret;

	lseek(s->fd, sector_num * 512, SEEK_SET);
	ret = read(s->fd, buf, nb_sectors * 512);
	if (ret != nb_sectors * 512)
	return -1;
	return 0;
	}

	static int raw_write(BlockDriverState *bs, int64_t sector_num,
	const uint8_t *buf, int nb_sectors)
	{
	BDRVRawState *s = bs->opaque;
	int ret;

	lseek(s->fd, sector_num * 512, SEEK_SET);
	ret = write(s->fd, buf, nb_sectors * 512);
	if (ret != nb_sectors * 512)
	return -1;
	return 0;
	}

	static void raw_close(BlockDriverState *bs)
	{
	BDRVRawState *s = bs->opaque;
	close(s->fd);
	}

	static int raw_create(const char *filename, int64_t total_size,
	const char *backing_file, int flags)
	{
	int fd;

	if (flags \|\| backing_file)
	return -ENOTSUP;

	fd = open(filename, O_WRONLY \| O_CREAT \| O_TRUNC \| O_BINARY \| O_LARGEFILE,
	0644);
	if (fd < 0)
	return -EIO;
	ftruncate(fd, total_size * 512);
	close(fd);
	return 0;
	}

	BlockDriver bdrv_raw = {
	"raw",
	sizeof(BDRVRawState),
	raw_probe,
	raw_open,
	raw_read,
	raw_write,
	raw_close,
	raw_create,
	};

	void bdrv_init(void)
	{
	bdrv_register(&bdrv_raw);
	#ifndef _WIN32
	bdrv_register(&bdrv_cow);
	#endif
	bdrv_register(&bdrv_qcow);
	bdrv_register(&bdrv_vmdk);
	bdrv_register(&bdrv_cloop);
	}