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block.c
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8554 lines (7309 loc) · 250 KB
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/*
* QEMU System Emulator block driver
*
* Copyright (c) 2003 Fabrice Bellard
* Copyright (c) 2020 Virtuozzo International GmbH.
*
* 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 "qemu/osdep.h"
#include "block/trace.h"
#include "block/block_int.h"
#include "block/blockjob.h"
#include "block/dirty-bitmap.h"
#include "block/fuse.h"
#include "block/nbd.h"
#include "block/qdict.h"
#include "qemu/error-report.h"
#include "block/module_block.h"
#include "qemu/main-loop.h"
#include "qemu/module.h"
#include "qapi/error.h"
#include "qobject/qdict.h"
#include "qobject/qjson.h"
#include "qobject/qnull.h"
#include "qobject/qstring.h"
#include "qapi/qobject-output-visitor.h"
#include "qapi/qapi-visit-block-core.h"
#include "system/block-backend.h"
#include "qemu/notify.h"
#include "qemu/option.h"
#include "qemu/coroutine.h"
#include "block/qapi.h"
#include "qemu/timer.h"
#include "qemu/cutils.h"
#include "qemu/id.h"
#include "qemu/range.h"
#include "qemu/rcu.h"
#include "block/coroutines.h"
#ifdef CONFIG_BSD
#include <sys/ioctl.h>
#include <sys/queue.h>
#if defined(HAVE_SYS_DISK_H)
#include <sys/disk.h>
#endif
#endif
#ifdef _WIN32
#include <windows.h>
#endif
#define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
/* Protected by BQL */
static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states =
QTAILQ_HEAD_INITIALIZER(graph_bdrv_states);
/* Protected by BQL */
static QTAILQ_HEAD(, BlockDriverState) all_bdrv_states =
QTAILQ_HEAD_INITIALIZER(all_bdrv_states);
/* Protected by BQL */
static QLIST_HEAD(, BlockDriver) bdrv_drivers =
QLIST_HEAD_INITIALIZER(bdrv_drivers);
static BlockDriverState *bdrv_open_inherit(const char *filename,
const char *reference,
QDict *options, int flags,
BlockDriverState *parent,
const BdrvChildClass *child_class,
BdrvChildRole child_role,
bool parse_filename,
Error **errp);
static bool bdrv_recurse_has_child(BlockDriverState *bs,
BlockDriverState *child);
static void GRAPH_WRLOCK
bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs);
static void GRAPH_WRLOCK
bdrv_remove_child(BdrvChild *child, Transaction *tran);
static int bdrv_reopen_prepare(BDRVReopenState *reopen_state,
BlockReopenQueue *queue,
Transaction *change_child_tran, Error **errp);
static void bdrv_reopen_commit(BDRVReopenState *reopen_state);
static void bdrv_reopen_abort(BDRVReopenState *reopen_state);
static bool bdrv_backing_overridden(BlockDriverState *bs);
static bool GRAPH_RDLOCK
bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx,
GHashTable *visited, Transaction *tran, Error **errp);
/* If non-zero, use only whitelisted block drivers */
static int use_bdrv_whitelist;
#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
size_t bdrv_opt_mem_align(BlockDriverState *bs)
{
if (!bs || !bs->drv) {
/* page size or 4k (hdd sector size) should be on the safe side */
return MAX(4096, qemu_real_host_page_size());
}
IO_CODE();
return bs->bl.opt_mem_alignment;
}
size_t bdrv_min_mem_align(BlockDriverState *bs)
{
if (!bs || !bs->drv) {
/* page size or 4k (hdd sector size) should be on the safe side */
return MAX(4096, qemu_real_host_page_size());
}
IO_CODE();
return bs->bl.min_mem_alignment;
}
/* check if the path starts with "<protocol>:" */
int path_has_protocol(const char *path)
{
const char *p;
#ifdef _WIN32
if (is_windows_drive(path) ||
is_windows_drive_prefix(path)) {
return 0;
}
p = path + strcspn(path, ":/\\");
#else
p = path + strcspn(path, ":/");
#endif
return *p == ':';
}
int path_is_absolute(const char *path)
{
#ifdef _WIN32
/* specific case for names like: "\\.\d:" */
if (is_windows_drive(path) || is_windows_drive_prefix(path)) {
return 1;
}
return (*path == '/' || *path == '\\');
#else
return (*path == '/');
#endif
}
/* if filename is absolute, just return its duplicate. Otherwise, build a
path to it by considering it is relative to base_path. URL are
supported. */
char *path_combine(const char *base_path, const char *filename)
{
const char *protocol_stripped = NULL;
const char *p, *p1;
char *result;
int len;
if (path_is_absolute(filename)) {
return g_strdup(filename);
}
if (path_has_protocol(base_path)) {
protocol_stripped = strchr(base_path, ':');
if (protocol_stripped) {
protocol_stripped++;
}
}
p = protocol_stripped ?: 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;
result = g_malloc(len + strlen(filename) + 1);
memcpy(result, base_path, len);
strcpy(result + len, filename);
return result;
}
/*
* Helper function for bdrv_parse_filename() implementations to remove optional
* protocol prefixes (especially "file:") from a filename and for putting the
* stripped filename into the options QDict if there is such a prefix.
*/
void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix,
QDict *options)
{
if (strstart(filename, prefix, &filename)) {
/* Stripping the explicit protocol prefix may result in a protocol
* prefix being (wrongly) detected (if the filename contains a colon) */
if (path_has_protocol(filename)) {
GString *fat_filename;
/* This means there is some colon before the first slash; therefore,
* this cannot be an absolute path */
assert(!path_is_absolute(filename));
/* And we can thus fix the protocol detection issue by prefixing it
* by "./" */
fat_filename = g_string_new("./");
g_string_append(fat_filename, filename);
assert(!path_has_protocol(fat_filename->str));
qdict_put(options, "filename",
qstring_from_gstring(fat_filename));
} else {
/* If no protocol prefix was detected, we can use the shortened
* filename as-is */
qdict_put_str(options, "filename", filename);
}
}
}
/* Returns whether the image file is opened as read-only. Note that this can
* return false and writing to the image file is still not possible because the
* image is inactivated. */
bool bdrv_is_read_only(BlockDriverState *bs)
{
IO_CODE();
return !(bs->open_flags & BDRV_O_RDWR);
}
static int GRAPH_RDLOCK
bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
bool ignore_allow_rdw, Error **errp)
{
IO_CODE();
/* Do not set read_only if copy_on_read is enabled */
if (bs->copy_on_read && read_only) {
error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled",
bdrv_get_device_or_node_name(bs));
return -EINVAL;
}
/* Do not clear read_only if it is prohibited */
if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) &&
!ignore_allow_rdw)
{
error_setg(errp, "Node '%s' is read only",
bdrv_get_device_or_node_name(bs));
return -EPERM;
}
return 0;
}
/*
* Called by a driver that can only provide a read-only image.
*
* Returns 0 if the node is already read-only or it could switch the node to
* read-only because BDRV_O_AUTO_RDONLY is set.
*
* Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set
* or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg
* is not NULL, it is used as the error message for the Error object.
*/
int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
Error **errp)
{
int ret = 0;
IO_CODE();
if (!(bs->open_flags & BDRV_O_RDWR)) {
return 0;
}
if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) {
goto fail;
}
ret = bdrv_can_set_read_only(bs, true, false, NULL);
if (ret < 0) {
goto fail;
}
bs->open_flags &= ~BDRV_O_RDWR;
return 0;
fail:
error_setg(errp, "%s", errmsg ?: "Image is read-only");
return -EACCES;
}
/*
* If @backing is empty, this function returns NULL without setting
* @errp. In all other cases, NULL will only be returned with @errp
* set.
*
* Therefore, a return value of NULL without @errp set means that
* there is no backing file; if @errp is set, there is one but its
* absolute filename cannot be generated.
*/
char *bdrv_get_full_backing_filename_from_filename(const char *backed,
const char *backing,
Error **errp)
{
if (backing[0] == '\0') {
return NULL;
} else if (path_has_protocol(backing) || path_is_absolute(backing)) {
return g_strdup(backing);
} else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) {
error_setg(errp, "Cannot use relative backing file names for '%s'",
backed);
return NULL;
} else {
return path_combine(backed, backing);
}
}
/*
* If @filename is empty or NULL, this function returns NULL without
* setting @errp. In all other cases, NULL will only be returned with
* @errp set.
*/
static char * GRAPH_RDLOCK
bdrv_make_absolute_filename(BlockDriverState *relative_to,
const char *filename, Error **errp)
{
char *dir, *full_name;
if (!filename || filename[0] == '\0') {
return NULL;
} else if (path_has_protocol(filename) || path_is_absolute(filename)) {
return g_strdup(filename);
}
dir = bdrv_dirname(relative_to, errp);
if (!dir) {
return NULL;
}
full_name = g_strconcat(dir, filename, NULL);
g_free(dir);
return full_name;
}
char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
{
GLOBAL_STATE_CODE();
return bdrv_make_absolute_filename(bs, bs->backing_file, errp);
}
void bdrv_register(BlockDriver *bdrv)
{
assert(bdrv->format_name);
GLOBAL_STATE_CODE();
QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
}
BlockDriverState *bdrv_new(void)
{
BlockDriverState *bs;
int i;
GLOBAL_STATE_CODE();
bs = g_new0(BlockDriverState, 1);
QLIST_INIT(&bs->dirty_bitmaps);
for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
QLIST_INIT(&bs->op_blockers[i]);
}
qemu_mutex_init(&bs->reqs_lock);
qemu_mutex_init(&bs->dirty_bitmap_mutex);
bs->refcnt = 1;
bs->aio_context = qemu_get_aio_context();
qemu_co_queue_init(&bs->flush_queue);
qemu_co_mutex_init(&bs->bsc_modify_lock);
bs->block_status_cache = g_new0(BdrvBlockStatusCache, 1);
for (i = 0; i < bdrv_drain_all_count; i++) {
bdrv_do_drained_begin_quiesce(bs, NULL);
}
QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list);
return bs;
}
static BlockDriver *bdrv_do_find_format(const char *format_name)
{
BlockDriver *drv1;
GLOBAL_STATE_CODE();
QLIST_FOREACH(drv1, &bdrv_drivers, list) {
if (!strcmp(drv1->format_name, format_name)) {
return drv1;
}
}
return NULL;
}
BlockDriver *bdrv_find_format(const char *format_name)
{
BlockDriver *drv1;
int i;
GLOBAL_STATE_CODE();
drv1 = bdrv_do_find_format(format_name);
if (drv1) {
return drv1;
}
/* The driver isn't registered, maybe we need to load a module */
for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
if (!strcmp(block_driver_modules[i].format_name, format_name)) {
Error *local_err = NULL;
int rv = block_module_load(block_driver_modules[i].library_name,
&local_err);
if (rv > 0) {
return bdrv_do_find_format(format_name);
} else if (rv < 0) {
error_report_err(local_err);
}
break;
}
}
return NULL;
}
static int bdrv_format_is_whitelisted(const char *format_name, bool read_only)
{
static const char *whitelist_rw[] = {
CONFIG_BDRV_RW_WHITELIST
NULL
};
static const char *whitelist_ro[] = {
CONFIG_BDRV_RO_WHITELIST
NULL
};
const char **p;
if (!whitelist_rw[0] && !whitelist_ro[0]) {
return 1; /* no whitelist, anything goes */
}
for (p = whitelist_rw; *p; p++) {
if (!strcmp(format_name, *p)) {
return 1;
}
}
if (read_only) {
for (p = whitelist_ro; *p; p++) {
if (!strcmp(format_name, *p)) {
return 1;
}
}
}
return 0;
}
int bdrv_is_whitelisted(BlockDriver *drv, bool read_only)
{
GLOBAL_STATE_CODE();
return bdrv_format_is_whitelisted(drv->format_name, read_only);
}
bool bdrv_uses_whitelist(void)
{
return use_bdrv_whitelist;
}
typedef struct CreateCo {
BlockDriver *drv;
char *filename;
QemuOpts *opts;
int ret;
Error *err;
} CreateCo;
int coroutine_fn bdrv_co_create(BlockDriver *drv, const char *filename,
QemuOpts *opts, Error **errp)
{
ERRP_GUARD();
int ret;
GLOBAL_STATE_CODE();
if (!drv->bdrv_co_create_opts) {
error_setg(errp, "Driver '%s' does not support image creation",
drv->format_name);
return -ENOTSUP;
}
ret = drv->bdrv_co_create_opts(drv, filename, opts, errp);
if (ret < 0 && !*errp) {
error_setg_errno(errp, -ret, "Could not create image");
}
return ret;
}
/**
* Helper function for bdrv_create_file_fallback(): Resize @blk to at
* least the given @minimum_size.
*
* On success, return @blk's actual length.
* Otherwise, return -errno.
*/
static int64_t coroutine_fn GRAPH_UNLOCKED
create_file_fallback_truncate(BlockBackend *blk, int64_t minimum_size,
Error **errp)
{
Error *local_err = NULL;
int64_t size;
int ret;
GLOBAL_STATE_CODE();
ret = blk_co_truncate(blk, minimum_size, false, PREALLOC_MODE_OFF, 0,
&local_err);
if (ret < 0 && ret != -ENOTSUP) {
error_propagate(errp, local_err);
return ret;
}
size = blk_co_getlength(blk);
if (size < 0) {
error_free(local_err);
error_setg_errno(errp, -size,
"Failed to inquire the new image file's length");
return size;
}
if (size < minimum_size) {
/* Need to grow the image, but we failed to do that */
error_propagate(errp, local_err);
return -ENOTSUP;
}
error_free(local_err);
local_err = NULL;
return size;
}
/**
* Helper function for bdrv_create_file_fallback(): Zero the first
* sector to remove any potentially pre-existing image header.
*/
static int coroutine_fn
create_file_fallback_zero_first_sector(BlockBackend *blk,
int64_t current_size,
Error **errp)
{
int64_t bytes_to_clear;
int ret;
GLOBAL_STATE_CODE();
bytes_to_clear = MIN(current_size, BDRV_SECTOR_SIZE);
if (bytes_to_clear) {
ret = blk_co_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP);
if (ret < 0) {
error_setg_errno(errp, -ret,
"Failed to clear the new image's first sector");
return ret;
}
}
return 0;
}
/**
* Simple implementation of bdrv_co_create_opts for protocol drivers
* which only support creation via opening a file
* (usually existing raw storage device)
*/
int coroutine_fn bdrv_co_create_opts_simple(BlockDriver *drv,
const char *filename,
QemuOpts *opts,
Error **errp)
{
ERRP_GUARD();
BlockBackend *blk;
QDict *options;
int64_t size = 0;
char *buf = NULL;
PreallocMode prealloc;
Error *local_err = NULL;
int ret;
GLOBAL_STATE_CODE();
size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
prealloc = qapi_enum_parse(&PreallocMode_lookup, buf,
PREALLOC_MODE_OFF, &local_err);
g_free(buf);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
if (prealloc != PREALLOC_MODE_OFF) {
error_setg(errp, "Unsupported preallocation mode '%s'",
PreallocMode_str(prealloc));
return -ENOTSUP;
}
options = qdict_new();
qdict_put_str(options, "driver", drv->format_name);
blk = blk_co_new_open(filename, NULL, options,
BDRV_O_RDWR | BDRV_O_RESIZE, errp);
if (!blk) {
error_prepend(errp, "Protocol driver '%s' does not support creating "
"new images, so an existing image must be selected as "
"the target; however, opening the given target as an "
"existing image failed: ",
drv->format_name);
return -EINVAL;
}
size = create_file_fallback_truncate(blk, size, errp);
if (size < 0) {
ret = size;
goto out;
}
ret = create_file_fallback_zero_first_sector(blk, size, errp);
if (ret < 0) {
goto out;
}
ret = 0;
out:
blk_co_unref(blk);
return ret;
}
int coroutine_fn bdrv_co_create_file(const char *filename, QemuOpts *opts,
Error **errp)
{
QemuOpts *protocol_opts;
BlockDriver *drv;
QDict *qdict;
int ret;
GLOBAL_STATE_CODE();
drv = bdrv_find_protocol(filename, true, errp);
if (drv == NULL) {
return -ENOENT;
}
if (!drv->create_opts) {
error_setg(errp, "Driver '%s' does not support image creation",
drv->format_name);
return -ENOTSUP;
}
/*
* 'opts' contains a QemuOptsList with a combination of format and protocol
* default values.
*
* The format properly removes its options, but the default values remain
* in 'opts->list'. So if the protocol has options with the same name
* (e.g. rbd has 'cluster_size' as qcow2), it will see the default values
* of the format, since for overlapping options, the format wins.
*
* To avoid this issue, lets convert QemuOpts to QDict, in this way we take
* only the set options, and then convert it back to QemuOpts, using the
* create_opts of the protocol. So the new QemuOpts, will contain only the
* protocol defaults.
*/
qdict = qemu_opts_to_qdict(opts, NULL);
protocol_opts = qemu_opts_from_qdict(drv->create_opts, qdict, errp);
if (protocol_opts == NULL) {
ret = -EINVAL;
goto out;
}
ret = bdrv_co_create(drv, filename, protocol_opts, errp);
out:
qemu_opts_del(protocol_opts);
qobject_unref(qdict);
return ret;
}
int coroutine_fn bdrv_co_delete_file(BlockDriverState *bs, Error **errp)
{
Error *local_err = NULL;
int ret;
IO_CODE();
assert(bs != NULL);
assert_bdrv_graph_readable();
if (!bs->drv) {
error_setg(errp, "Block node '%s' is not opened", bs->filename);
return -ENOMEDIUM;
}
if (!bs->drv->bdrv_co_delete_file) {
error_setg(errp, "Driver '%s' does not support image deletion",
bs->drv->format_name);
return -ENOTSUP;
}
ret = bs->drv->bdrv_co_delete_file(bs, &local_err);
if (ret < 0) {
error_propagate(errp, local_err);
}
return ret;
}
void coroutine_fn bdrv_co_delete_file_noerr(BlockDriverState *bs)
{
Error *local_err = NULL;
int ret;
IO_CODE();
if (!bs) {
return;
}
ret = bdrv_co_delete_file(bs, &local_err);
/*
* ENOTSUP will happen if the block driver doesn't support
* the 'bdrv_co_delete_file' interface. This is a predictable
* scenario and shouldn't be reported back to the user.
*/
if (ret == -ENOTSUP) {
error_free(local_err);
} else if (ret < 0) {
error_report_err(local_err);
}
}
/**
* Try to get @bs's logical and physical block size.
* On success, store them in @bsz struct and return 0.
* On failure return -errno.
* @bs must not be empty.
*/
int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
{
BlockDriver *drv = bs->drv;
BlockDriverState *filtered = bdrv_filter_bs(bs);
GLOBAL_STATE_CODE();
if (drv && drv->bdrv_probe_blocksizes) {
return drv->bdrv_probe_blocksizes(bs, bsz);
} else if (filtered) {
return bdrv_probe_blocksizes(filtered, bsz);
}
return -ENOTSUP;
}
/**
* Try to get @bs's geometry (cyls, heads, sectors).
* On success, store them in @geo struct and return 0.
* On failure return -errno.
* @bs must not be empty.
*/
int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
{
BlockDriver *drv = bs->drv;
BlockDriverState *filtered;
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
if (drv && drv->bdrv_probe_geometry) {
return drv->bdrv_probe_geometry(bs, geo);
}
filtered = bdrv_filter_bs(bs);
if (filtered) {
return bdrv_probe_geometry(filtered, geo);
}
return -ENOTSUP;
}
/*
* Create a uniquely-named empty temporary file.
* Return the actual file name used upon success, otherwise NULL.
* This string should be freed with g_free() when not needed any longer.
*
* Note: creating a temporary file for the caller to (re)open is
* inherently racy. Use g_file_open_tmp() instead whenever practical.
*/
char *create_tmp_file(Error **errp)
{
int fd;
const char *tmpdir;
g_autofree char *filename = NULL;
tmpdir = g_get_tmp_dir();
#ifndef _WIN32
/*
* See commit 69bef79 ("block: use /var/tmp instead of /tmp for -snapshot")
*
* This function is used to create temporary disk images (like -snapshot),
* so the files can become very large. /tmp is often a tmpfs where as
* /var/tmp is usually on a disk, so more appropriate for disk images.
*/
if (!g_strcmp0(tmpdir, "/tmp")) {
tmpdir = "/var/tmp";
}
#endif
filename = g_strdup_printf("%s/vl.XXXXXX", tmpdir);
fd = g_mkstemp(filename);
if (fd < 0) {
error_setg_errno(errp, errno, "Could not open temporary file '%s'",
filename);
return NULL;
}
close(fd);
return g_steal_pointer(&filename);
}
/*
* 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;
GLOBAL_STATE_CODE();
QLIST_FOREACH(d, &bdrv_drivers, list) {
if (d->bdrv_probe_device) {
score = d->bdrv_probe_device(filename);
if (score > score_max) {
score_max = score;
drv = d;
}
}
}
return drv;
}
static BlockDriver *bdrv_do_find_protocol(const char *protocol)
{
BlockDriver *drv1;
GLOBAL_STATE_CODE();
QLIST_FOREACH(drv1, &bdrv_drivers, list) {
if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) {
return drv1;
}
}
return NULL;
}
BlockDriver *bdrv_find_protocol(const char *filename,
bool allow_protocol_prefix,
Error **errp)
{
BlockDriver *drv1;
char protocol[128];
int len;
const char *p;
int i;
GLOBAL_STATE_CODE();
/*
* XXX(hch): we really should not let host device detection
* override an explicit protocol specification, but moving this
* later breaks access to device names with colons in them.
* Thanks to the brain-dead persistent naming schemes on udev-
* based Linux systems those actually are quite common.
*/
drv1 = find_hdev_driver(filename);
if (drv1) {
return drv1;
}
if (!path_has_protocol(filename) || !allow_protocol_prefix) {
return &bdrv_file;
}
p = strchr(filename, ':');
assert(p != NULL);
len = p - filename;
if (len > sizeof(protocol) - 1)
len = sizeof(protocol) - 1;
memcpy(protocol, filename, len);
protocol[len] = '\0';
drv1 = bdrv_do_find_protocol(protocol);
if (drv1) {
return drv1;
}
for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
if (block_driver_modules[i].protocol_name &&
!strcmp(block_driver_modules[i].protocol_name, protocol)) {
int rv = block_module_load(block_driver_modules[i].library_name, errp);
if (rv > 0) {
drv1 = bdrv_do_find_protocol(protocol);
} else if (rv < 0) {
return NULL;
}
break;
}
}
if (!drv1) {
error_setg(errp, "Unknown protocol '%s'", protocol);
}
return drv1;
}
/*
* Guess image format by probing its contents.
* This is not a good idea when your image is raw (CVE-2008-2004), but
* we do it anyway for backward compatibility.
*
* @buf contains the image's first @buf_size bytes.
* @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE,
* but can be smaller if the image file is smaller)
* @filename is its filename.
*
* For all block drivers, call the bdrv_probe() method to get its
* probing score.
* Return the first block driver with the highest probing score.
*/
BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size,
const char *filename)
{
int score_max = 0, score;
BlockDriver *drv = NULL, *d;
IO_CODE();
QLIST_FOREACH(d, &bdrv_drivers, list) {