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block.c
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/*
* 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 "config-host.h"
#include "qemu-common.h"
#include "monitor.h"
#include "block_int.h"
#include "module.h"
#include "qemu-objects.h"
#ifdef CONFIG_BSD
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/queue.h>
#ifndef __DragonFly__
#include <sys/disk.h>
#endif
#endif
#ifdef _WIN32
#include <windows.h>
#endif
static BlockDriverAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque);
static BlockDriverAIOCB *bdrv_aio_writev_em(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque);
static BlockDriverAIOCB *bdrv_aio_flush_em(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque);
static int bdrv_read_em(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors);
static int bdrv_write_em(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors);
static QTAILQ_HEAD(, BlockDriverState) bdrv_states =
QTAILQ_HEAD_INITIALIZER(bdrv_states);
static BlockDriver *first_drv;
/* If non-zero, use only whitelisted block drivers */
static int use_bdrv_whitelist;
int path_is_absolute(const char *path)
{
const char *p;
#ifdef _WIN32
/* specific case for names like: "\\.\d:" */
if (*path == '/' || *path == '\\')
return 1;
#endif
p = strchr(path, ':');
if (p)
p++;
else
p = path;
#ifdef _WIN32
return (*p == '/' || *p == '\\');
#else
return (*p == '/');
#endif
}
/* if filename is absolute, just copy it to dest. Otherwise, build a
path to it by considering it is relative to base_path. URL are
supported. */
void path_combine(char *dest, int dest_size,
const char *base_path,
const char *filename)
{
const char *p, *p1;
int len;
if (dest_size <= 0)
return;
if (path_is_absolute(filename)) {
pstrcpy(dest, dest_size, filename);
} else {
p = strchr(base_path, ':');
if (p)
p++;
else
p = base_path;
p1 = strrchr(base_path, '/');
#ifdef _WIN32
{
const char *p2;
p2 = strrchr(base_path, '\\');
if (!p1 || p2 > p1)
p1 = p2;
}
#endif
if (p1)
p1++;
else
p1 = base_path;
if (p1 > p)
p = p1;
len = p - base_path;
if (len > dest_size - 1)
len = dest_size - 1;
memcpy(dest, base_path, len);
dest[len] = '\0';
pstrcat(dest, dest_size, filename);
}
}
void bdrv_register(BlockDriver *bdrv)
{
if (!bdrv->bdrv_aio_readv) {
/* add AIO emulation layer */
bdrv->bdrv_aio_readv = bdrv_aio_readv_em;
bdrv->bdrv_aio_writev = bdrv_aio_writev_em;
} else if (!bdrv->bdrv_read) {
/* add synchronous IO emulation layer */
bdrv->bdrv_read = bdrv_read_em;
bdrv->bdrv_write = bdrv_write_em;
}
if (!bdrv->bdrv_aio_flush)
bdrv->bdrv_aio_flush = bdrv_aio_flush_em;
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 *bs;
bs = qemu_mallocz(sizeof(BlockDriverState));
pstrcpy(bs->device_name, sizeof(bs->device_name), device_name);
if (device_name[0] != '\0') {
QTAILQ_INSERT_TAIL(&bdrv_states, bs, list);
}
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;
}
static int bdrv_is_whitelisted(BlockDriver *drv)
{
static const char *whitelist[] = {
CONFIG_BDRV_WHITELIST
};
const char **p;
if (!whitelist[0])
return 1; /* no whitelist, anything goes */
for (p = whitelist; *p; p++) {
if (!strcmp(drv->format_name, *p)) {
return 1;
}
}
return 0;
}
BlockDriver *bdrv_find_whitelisted_format(const char *format_name)
{
BlockDriver *drv = bdrv_find_format(format_name);
return drv && bdrv_is_whitelisted(drv) ? drv : NULL;
}
int bdrv_create(BlockDriver *drv, const char* filename,
QEMUOptionParameter *options)
{
if (!drv->bdrv_create)
return -ENOTSUP;
return drv->bdrv_create(filename, options);
}
#ifdef _WIN32
void get_tmp_filename(char *filename, int size)
{
char temp_dir[MAX_PATH];
GetTempPath(MAX_PATH, temp_dir);
GetTempFileName(temp_dir, "qem", 0, filename);
}
#else
void get_tmp_filename(char *filename, int size)
{
int fd;
const char *tmpdir;
/* XXX: race condition possible */
tmpdir = getenv("TMPDIR");
if (!tmpdir)
tmpdir = "/tmp";
snprintf(filename, size, "%s/vl.XXXXXX", tmpdir);
fd = mkstemp(filename);
close(fd);
}
#endif
#ifdef _WIN32
static int is_windows_drive_prefix(const char *filename)
{
return (((filename[0] >= 'a' && filename[0] <= 'z') ||
(filename[0] >= 'A' && filename[0] <= 'Z')) &&
filename[1] == ':');
}
int is_windows_drive(const char *filename)
{
if (is_windows_drive_prefix(filename) &&
filename[2] == '\0')
return 1;
if (strstart(filename, "\\\\.\\", NULL) ||
strstart(filename, "//./", NULL))
return 1;
return 0;
}
#endif
static BlockDriver *find_protocol(const char *filename)
{
BlockDriver *drv1;
char protocol[128];
int len;
const char *p;
#ifdef _WIN32
if (is_windows_drive(filename) ||
is_windows_drive_prefix(filename))
return bdrv_find_format("raw");
#endif
p = strchr(filename, ':');
if (!p)
return bdrv_find_format("raw");
len = p - filename;
if (len > sizeof(protocol) - 1)
len = sizeof(protocol) - 1;
memcpy(protocol, filename, len);
protocol[len] = '\0';
for(drv1 = first_drv; drv1 != NULL; drv1 = drv1->next) {
if (drv1->protocol_name &&
!strcmp(drv1->protocol_name, protocol))
return drv1;
}
return NULL;
}
/*
* Detect host devices. By convention, /dev/cdrom[N] is always
* recognized as a host CDROM.
*/
static BlockDriver *find_hdev_driver(const char *filename)
{
int score_max = 0, score;
BlockDriver *drv = NULL, *d;
for (d = first_drv; d; d = d->next) {
if (d->bdrv_probe_device) {
score = d->bdrv_probe_device(filename);
if (score > score_max) {
score_max = score;
drv = d;
}
}
}
return drv;
}
static BlockDriver *find_image_format(const char *filename)
{
int ret, score, score_max;
BlockDriver *drv1, *drv;
uint8_t buf[2048];
BlockDriverState *bs;
drv = find_protocol(filename);
/* no need to test disk image formats for vvfat */
if (drv && strcmp(drv->format_name, "vvfat") == 0)
return drv;
ret = bdrv_file_open(&bs, filename, 0);
if (ret < 0)
return NULL;
ret = bdrv_pread(bs, 0, buf, sizeof(buf));
bdrv_delete(bs);
if (ret < 0) {
return NULL;
}
score_max = 0;
for(drv1 = first_drv; drv1 != NULL; drv1 = drv1->next) {
if (drv1->bdrv_probe) {
score = drv1->bdrv_probe(buf, ret, filename);
if (score > score_max) {
score_max = score;
drv = drv1;
}
}
}
return drv;
}
int bdrv_file_open(BlockDriverState **pbs, const char *filename, int flags)
{
BlockDriverState *bs;
BlockDriver *drv;
int ret;
drv = find_protocol(filename);
if (!drv) {
return -ENOENT;
}
bs = bdrv_new("");
ret = bdrv_open(bs, filename, flags, drv);
if (ret < 0) {
bdrv_delete(bs);
return ret;
}
bs->growable = 1;
*pbs = bs;
return 0;
}
int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
BlockDriver *drv)
{
int ret, open_flags;
char tmp_filename[PATH_MAX];
char backing_filename[PATH_MAX];
bs->is_temporary = 0;
bs->encrypted = 0;
bs->valid_key = 0;
bs->open_flags = flags;
/* buffer_alignment defaulted to 512, drivers can change this value */
bs->buffer_alignment = 512;
if (flags & BDRV_O_SNAPSHOT) {
BlockDriverState *bs1;
int64_t total_size;
int is_protocol = 0;
BlockDriver *bdrv_qcow2;
QEMUOptionParameter *options;
/* 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("");
ret = bdrv_open(bs1, filename, 0, drv);
if (ret < 0) {
bdrv_delete(bs1);
return ret;
}
total_size = bdrv_getlength(bs1) >> BDRV_SECTOR_BITS;
if (bs1->drv && bs1->drv->protocol_name)
is_protocol = 1;
bdrv_delete(bs1);
get_tmp_filename(tmp_filename, sizeof(tmp_filename));
/* Real path is meaningless for protocols */
if (is_protocol)
snprintf(backing_filename, sizeof(backing_filename),
"%s", filename);
else if (!realpath(filename, backing_filename))
return -errno;
bdrv_qcow2 = bdrv_find_format("qcow2");
options = parse_option_parameters("", bdrv_qcow2->create_options, NULL);
set_option_parameter_int(options, BLOCK_OPT_SIZE, total_size * 512);
set_option_parameter(options, BLOCK_OPT_BACKING_FILE, backing_filename);
if (drv) {
set_option_parameter(options, BLOCK_OPT_BACKING_FMT,
drv->format_name);
}
ret = bdrv_create(bdrv_qcow2, tmp_filename, options);
if (ret < 0) {
return ret;
}
filename = tmp_filename;
drv = bdrv_qcow2;
bs->is_temporary = 1;
}
pstrcpy(bs->filename, sizeof(bs->filename), filename);
if (!drv) {
drv = find_hdev_driver(filename);
if (!drv) {
drv = find_image_format(filename);
}
}
if (!drv) {
ret = -ENOENT;
goto unlink_and_fail;
}
if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv)) {
ret = -ENOTSUP;
goto unlink_and_fail;
}
bs->drv = drv;
bs->opaque = qemu_mallocz(drv->instance_size);
/*
* Yes, BDRV_O_NOCACHE aka O_DIRECT means we have to present a
* write cache to the guest. We do need the fdatasync to flush
* out transactions for block allocations, and we maybe have a
* volatile write cache in our backing device to deal with.
*/
if (flags & (BDRV_O_CACHE_WB|BDRV_O_NOCACHE))
bs->enable_write_cache = 1;
/*
* Clear flags that are internal to the block layer before opening the
* image.
*/
open_flags = flags & ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
/*
* Snapshots should be writeable.
*/
if (bs->is_temporary) {
open_flags |= BDRV_O_RDWR;
}
ret = drv->bdrv_open(bs, filename, open_flags);
if (ret < 0) {
goto free_and_fail;
}
bs->keep_read_only = bs->read_only = !(open_flags & BDRV_O_RDWR);
if (drv->bdrv_getlength) {
bs->total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
}
#ifndef _WIN32
if (bs->is_temporary) {
unlink(filename);
}
#endif
if ((flags & BDRV_O_NO_BACKING) == 0 && bs->backing_file[0] != '\0') {
/* if there is a backing file, use it */
BlockDriver *back_drv = NULL;
bs->backing_hd = bdrv_new("");
path_combine(backing_filename, sizeof(backing_filename),
filename, bs->backing_file);
if (bs->backing_format[0] != '\0')
back_drv = bdrv_find_format(bs->backing_format);
/* backing files always opened read-only */
open_flags &= ~BDRV_O_RDWR;
ret = bdrv_open(bs->backing_hd, backing_filename, open_flags, back_drv);
if (ret < 0) {
bdrv_close(bs);
return ret;
}
if (bs->is_temporary) {
bs->backing_hd->keep_read_only = !(flags & BDRV_O_RDWR);
} else {
/* base image inherits from "parent" */
bs->backing_hd->keep_read_only = bs->keep_read_only;
}
}
if (!bdrv_key_required(bs)) {
/* call the change callback */
bs->media_changed = 1;
if (bs->change_cb)
bs->change_cb(bs->change_opaque);
}
return 0;
free_and_fail:
qemu_free(bs->opaque);
bs->opaque = NULL;
bs->drv = NULL;
unlink_and_fail:
if (bs->is_temporary)
unlink(filename);
return ret;
}
void bdrv_close(BlockDriverState *bs)
{
if (bs->drv) {
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;
/* call the change callback */
bs->media_changed = 1;
if (bs->change_cb)
bs->change_cb(bs->change_opaque);
}
}
void bdrv_delete(BlockDriverState *bs)
{
/* remove from list, if necessary */
if (bs->device_name[0] != '\0') {
QTAILQ_REMOVE(&bdrv_states, bs, list);
}
bdrv_close(bs);
qemu_free(bs);
}
/*
* Run consistency checks on an image
*
* Returns the number of errors or -errno when an internal error occurs
*/
int bdrv_check(BlockDriverState *bs)
{
if (bs->drv->bdrv_check == NULL) {
return -ENOTSUP;
}
return bs->drv->bdrv_check(bs);
}
/* commit COW file into the raw image */
int bdrv_commit(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
int64_t i, total_sectors;
int n, j, ro, open_flags;
int ret = 0, rw_ret = 0;
unsigned char sector[512];
char filename[1024];
BlockDriverState *bs_rw, *bs_ro;
if (!drv)
return -ENOMEDIUM;
if (!bs->backing_hd) {
return -ENOTSUP;
}
if (bs->backing_hd->keep_read_only) {
return -EACCES;
}
ro = bs->backing_hd->read_only;
strncpy(filename, bs->backing_hd->filename, sizeof(filename));
open_flags = bs->backing_hd->open_flags;
if (ro) {
/* re-open as RW */
bdrv_delete(bs->backing_hd);
bs->backing_hd = NULL;
bs_rw = bdrv_new("");
rw_ret = bdrv_open(bs_rw, filename, open_flags | BDRV_O_RDWR, NULL);
if (rw_ret < 0) {
bdrv_delete(bs_rw);
/* try to re-open read-only */
bs_ro = bdrv_new("");
ret = bdrv_open(bs_ro, filename, open_flags & ~BDRV_O_RDWR, NULL);
if (ret < 0) {
bdrv_delete(bs_ro);
/* drive not functional anymore */
bs->drv = NULL;
return ret;
}
bs->backing_hd = bs_ro;
return rw_ret;
}
bs->backing_hd = bs_rw;
}
total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
for (i = 0; i < total_sectors;) {
if (drv->bdrv_is_allocated(bs, i, 65536, &n)) {
for(j = 0; j < n; j++) {
if (bdrv_read(bs, i, sector, 1) != 0) {
ret = -EIO;
goto ro_cleanup;
}
if (bdrv_write(bs->backing_hd, i, sector, 1) != 0) {
ret = -EIO;
goto ro_cleanup;
}
i++;
}
} else {
i += n;
}
}
if (drv->bdrv_make_empty) {
ret = drv->bdrv_make_empty(bs);
bdrv_flush(bs);
}
/*
* Make sure all data we wrote to the backing device is actually
* stable on disk.
*/
if (bs->backing_hd)
bdrv_flush(bs->backing_hd);
ro_cleanup:
if (ro) {
/* re-open as RO */
bdrv_delete(bs->backing_hd);
bs->backing_hd = NULL;
bs_ro = bdrv_new("");
ret = bdrv_open(bs_ro, filename, open_flags & ~BDRV_O_RDWR, NULL);
if (ret < 0) {
bdrv_delete(bs_ro);
/* drive not functional anymore */
bs->drv = NULL;
return ret;
}
bs->backing_hd = bs_ro;
bs->backing_hd->keep_read_only = 0;
}
return ret;
}
/*
* Return values:
* 0 - success
* -EINVAL - backing format specified, but no file
* -ENOSPC - can't update the backing file because no space is left in the
* image file header
* -ENOTSUP - format driver doesn't support changing the backing file
*/
int bdrv_change_backing_file(BlockDriverState *bs,
const char *backing_file, const char *backing_fmt)
{
BlockDriver *drv = bs->drv;
if (drv->bdrv_change_backing_file != NULL) {
return drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
} else {
return -ENOTSUP;
}
}
static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset,
size_t size)
{
int64_t len;
if (!bdrv_is_inserted(bs))
return -ENOMEDIUM;
if (bs->growable)
return 0;
len = bdrv_getlength(bs);
if (offset < 0)
return -EIO;
if ((offset > len) || (len - offset < size))
return -EIO;
return 0;
}
static int bdrv_check_request(BlockDriverState *bs, int64_t sector_num,
int nb_sectors)
{
return bdrv_check_byte_request(bs, sector_num * 512, nb_sectors * 512);
}
/* return < 0 if error. See bdrv_write() for the return codes */
int bdrv_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
BlockDriver *drv = bs->drv;
if (!drv)
return -ENOMEDIUM;
if (bdrv_check_request(bs, sector_num, nb_sectors))
return -EIO;
return drv->bdrv_read(bs, sector_num, buf, nb_sectors);
}
static void set_dirty_bitmap(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int dirty)
{
int64_t start, end;
unsigned long val, idx, bit;
start = sector_num / BDRV_SECTORS_PER_DIRTY_CHUNK;
end = (sector_num + nb_sectors - 1) / BDRV_SECTORS_PER_DIRTY_CHUNK;
for (; start <= end; start++) {
idx = start / (sizeof(unsigned long) * 8);
bit = start % (sizeof(unsigned long) * 8);
val = bs->dirty_bitmap[idx];
if (dirty) {
if (!(val & (1 << bit))) {
bs->dirty_count++;
val |= 1 << bit;
}
} else {
if (val & (1 << bit)) {
bs->dirty_count--;
val &= ~(1 << bit);
}
}
bs->dirty_bitmap[idx] = val;
}
}
/* Return < 0 if error. Important errors are:
-EIO generic I/O error (may happen for all errors)
-ENOMEDIUM No media inserted.
-EINVAL Invalid sector number or nb_sectors
-EACCES Trying to write a read-only device
*/
int bdrv_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
BlockDriver *drv = bs->drv;
if (!bs->drv)
return -ENOMEDIUM;
if (bs->read_only)
return -EACCES;
if (bdrv_check_request(bs, sector_num, nb_sectors))
return -EIO;
if (bs->dirty_bitmap) {
set_dirty_bitmap(bs, sector_num, nb_sectors, 1);
}
return drv->bdrv_write(bs, sector_num, buf, nb_sectors);
}
int bdrv_pread(BlockDriverState *bs, int64_t offset,
void *buf, int count1)
{
uint8_t tmp_buf[BDRV_SECTOR_SIZE];
int len, nb_sectors, count;
int64_t sector_num;
int ret;
count = count1;
/* first read to align to sector start */
len = (BDRV_SECTOR_SIZE - offset) & (BDRV_SECTOR_SIZE - 1);
if (len > count)
len = count;
sector_num = offset >> BDRV_SECTOR_BITS;
if (len > 0) {
if ((ret = bdrv_read(bs, sector_num, tmp_buf, 1)) < 0)
return ret;
memcpy(buf, tmp_buf + (offset & (BDRV_SECTOR_SIZE - 1)), len);
count -= len;
if (count == 0)
return count1;
sector_num++;
buf += len;
}
/* read the sectors "in place" */
nb_sectors = count >> BDRV_SECTOR_BITS;
if (nb_sectors > 0) {
if ((ret = bdrv_read(bs, sector_num, buf, nb_sectors)) < 0)
return ret;
sector_num += nb_sectors;
len = nb_sectors << BDRV_SECTOR_BITS;
buf += len;
count -= len;
}
/* add data from the last sector */
if (count > 0) {
if ((ret = bdrv_read(bs, sector_num, tmp_buf, 1)) < 0)
return ret;
memcpy(buf, tmp_buf, count);
}
return count1;
}
int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
const void *buf, int count1)
{
uint8_t tmp_buf[BDRV_SECTOR_SIZE];
int len, nb_sectors, count;
int64_t sector_num;
int ret;
count = count1;
/* first write to align to sector start */
len = (BDRV_SECTOR_SIZE - offset) & (BDRV_SECTOR_SIZE - 1);
if (len > count)
len = count;
sector_num = offset >> BDRV_SECTOR_BITS;
if (len > 0) {
if ((ret = bdrv_read(bs, sector_num, tmp_buf, 1)) < 0)
return ret;
memcpy(tmp_buf + (offset & (BDRV_SECTOR_SIZE - 1)), buf, len);
if ((ret = bdrv_write(bs, sector_num, tmp_buf, 1)) < 0)
return ret;
count -= len;
if (count == 0)
return count1;
sector_num++;
buf += len;
}
/* write the sectors "in place" */
nb_sectors = count >> BDRV_SECTOR_BITS;
if (nb_sectors > 0) {
if ((ret = bdrv_write(bs, sector_num, buf, nb_sectors)) < 0)
return ret;
sector_num += nb_sectors;
len = nb_sectors << BDRV_SECTOR_BITS;
buf += len;
count -= len;
}
/* add data from the last sector */
if (count > 0) {
if ((ret = bdrv_read(bs, sector_num, tmp_buf, 1)) < 0)
return ret;
memcpy(tmp_buf, buf, count);
if ((ret = bdrv_write(bs, sector_num, tmp_buf, 1)) < 0)
return ret;
}
return count1;
}
/**
* Truncate file to 'offset' bytes (needed only for file protocols)
*/
int bdrv_truncate(BlockDriverState *bs, int64_t offset)
{
BlockDriver *drv = bs->drv;
if (!drv)
return -ENOMEDIUM;
if (!drv->bdrv_truncate)
return -ENOTSUP;
if (bs->read_only)
return -EACCES;
return drv->bdrv_truncate(bs, offset);
}
/**
* Length of a file in bytes. Return < 0 if error or unknown.
*/
int64_t bdrv_getlength(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
if (!drv)
return -ENOMEDIUM;
if (!drv->bdrv_getlength) {
/* legacy mode */
return bs->total_sectors * BDRV_SECTOR_SIZE;
}
return drv->bdrv_getlength(bs);
}
/* return 0 as number of sectors if no device present or error */
void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr)
{
int64_t length;
length = bdrv_getlength(bs);
if (length < 0)
length = 0;
else
length = length >> BDRV_SECTOR_BITS;
*nb_sectors_ptr = length;
}
struct partition {
uint8_t boot_ind; /* 0x80 - active */
uint8_t head; /* starting head */
uint8_t sector; /* starting sector */
uint8_t cyl; /* starting cylinder */
uint8_t sys_ind; /* What partition type */
uint8_t end_head; /* end head */
uint8_t end_sector; /* end sector */
uint8_t end_cyl; /* end cylinder */
uint32_t start_sect; /* starting sector counting from 0 */
uint32_t nr_sects; /* nr of sectors in partition */
} __attribute__((packed));
/* try to guess the disk logical geometry from the MSDOS partition table. Return 0 if OK, -1 if could not guess */
static int guess_disk_lchs(BlockDriverState *bs,
int *pcylinders, int *pheads, int *psectors)
{
uint8_t buf[512];
int ret, i, heads, sectors, cylinders;
struct partition *p;
uint32_t nr_sects;
uint64_t nb_sectors;
bdrv_get_geometry(bs, &nb_sectors);
ret = bdrv_read(bs, 0, buf, 1);
if (ret < 0)
return -1;
/* test msdos magic */
if (buf[510] != 0x55 || buf[511] != 0xaa)
return -1;
for(i = 0; i < 4; i++) {
p = ((struct partition *)(buf + 0x1be)) + i;
nr_sects = le32_to_cpu(p->nr_sects);
if (nr_sects && p->end_head) {
/* We make the assumption that the partition terminates on
a cylinder boundary */
heads = p->end_head + 1;
sectors = p->end_sector & 63;
if (sectors == 0)
continue;
cylinders = nb_sectors / (heads * sectors);
if (cylinders < 1 || cylinders > 16383)
continue;
*pheads = heads;
*psectors = sectors;
*pcylinders = cylinders;
#if 0
printf("guessed geometry: LCHS=%d %d %d\n",
cylinders, heads, sectors);
#endif
return 0;
}
}
return -1;
}
void bdrv_guess_geometry(BlockDriverState *bs, int *pcyls, int *pheads, int *psecs)
{
int translation, lba_detected = 0;
int cylinders, heads, secs;
uint64_t nb_sectors;
/* if a geometry hint is available, use it */
bdrv_get_geometry(bs, &nb_sectors);
bdrv_get_geometry_hint(bs, &cylinders, &heads, &secs);
translation = bdrv_get_translation_hint(bs);
if (cylinders != 0) {
*pcyls = cylinders;
*pheads = heads;
*psecs = secs;
} else {
if (guess_disk_lchs(bs, &cylinders, &heads, &secs) == 0) {
if (heads > 16) {
/* if heads > 16, it means that a BIOS LBA
translation was active, so the default
hardware geometry is OK */
lba_detected = 1;
goto default_geometry;
} else {
*pcyls = cylinders;