better support of host drives

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@2124 c046a42c-6fe2-441c-8c8c-71466251a162

better support of host drives
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@2124 c046a42c-6fe2-441c-8c8c-71466251a162
bellard
1 parent 66c6ef76
Showing 5 changed files with 808 additions and 164 deletions
block-raw.c
block.c
block_int.h
qemu-doc.texi
vl.h
@@ -46,100 +46,42 @@
 #ifdef __sun__
 #include <sys/dkio.h>
 #endif
+#ifdef __linux__
+#include <sys/ioctl.h>
+#include <linux/cdrom.h>
+#include <linux/fd.h>
+#endif
-typedef struct BDRVRawState {
-    int fd;
-} BDRVRawState;
+//#define DEBUG_FLOPPY
-#ifdef CONFIG_COCOA
-static kern_return_t FindEjectableCDMedia( io_iterator_t *mediaIterator );
-static kern_return_t GetBSDPath( io_iterator_t mediaIterator, char *bsdPath, CFIndex maxPathSize );
-
-kern_return_t FindEjectableCDMedia( io_iterator_t *mediaIterator )
-{
-    kern_return_t       kernResult; 
-    mach_port_t     masterPort;
-    CFMutableDictionaryRef  classesToMatch;
-
-    kernResult = IOMasterPort( MACH_PORT_NULL, &masterPort );
-    if ( KERN_SUCCESS != kernResult ) {
-        printf( "IOMasterPort returned %d\n", kernResult );
-    }
-    
-    classesToMatch = IOServiceMatching( kIOCDMediaClass ); 
-    if ( classesToMatch == NULL ) {
-        printf( "IOServiceMatching returned a NULL dictionary.\n" );
-    } else {
-    CFDictionarySetValue( classesToMatch, CFSTR( kIOMediaEjectableKey ), kCFBooleanTrue );
-    }
-    kernResult = IOServiceGetMatchingServices( masterPort, classesToMatch, mediaIterator );
-    if ( KERN_SUCCESS != kernResult )
-    {
-        printf( "IOServiceGetMatchingServices returned %d\n", kernResult );
-    }
-    
-    return kernResult;
-}
+#define FTYPE_FILE   0
+#define FTYPE_CD     1
+#define FTYPE_FD     2
-kern_return_t GetBSDPath( io_iterator_t mediaIterator, char *bsdPath, CFIndex maxPathSize )
-{
-    io_object_t     nextMedia;
-    kern_return_t   kernResult = KERN_FAILURE;
-    *bsdPath = '\0';
-    nextMedia = IOIteratorNext( mediaIterator );
-    if ( nextMedia )
-    {
-        CFTypeRef   bsdPathAsCFString;
-    bsdPathAsCFString = IORegistryEntryCreateCFProperty( nextMedia, CFSTR( kIOBSDNameKey ), kCFAllocatorDefault, 0 );
-        if ( bsdPathAsCFString ) {
-            size_t devPathLength;
-            strcpy( bsdPath, _PATH_DEV );
-            strcat( bsdPath, "r" );
-            devPathLength = strlen( bsdPath );
-            if ( CFStringGetCString( bsdPathAsCFString, bsdPath + devPathLength, maxPathSize - devPathLength, kCFStringEncodingASCII ) ) {
-                kernResult = KERN_SUCCESS;
-            }
-            CFRelease( bsdPathAsCFString );
-        }
-        IOObjectRelease( nextMedia );
-    }
-    
-    return kernResult;
-}
+/* if the FD is not accessed during that time (in ms), we try to
+   reopen it to see if the disk has been changed */
+#define FD_OPEN_TIMEOUT 1000
+typedef struct BDRVRawState {
+    int fd;
+    int type;
+#if defined(__linux__)
+    /* linux floppy specific */
+    int fd_open_flags;
+    int64_t fd_open_time;
+    int64_t fd_error_time;
+    int fd_got_error;
+    int fd_media_changed;
 #endif
+} BDRVRawState;
+
+static int fd_open(BlockDriverState *bs);
 static int raw_open(BlockDriverState *bs, const char *filename, int flags)
 {
     BDRVRawState *s = bs->opaque;
-    int fd, open_flags;
+    int fd, open_flags, ret;
-#ifdef CONFIG_COCOA
-    if (strstart(filename, "/dev/cdrom", NULL)) {
-        kern_return_t kernResult;
-        io_iterator_t mediaIterator;
-        char bsdPath[ MAXPATHLEN ];
-        int fd;
- 
-        kernResult = FindEjectableCDMedia( &mediaIterator );
-        kernResult = GetBSDPath( mediaIterator, bsdPath, sizeof( bsdPath ) );
-    
-        if ( bsdPath[ 0 ] != '\0' ) {
-            strcat(bsdPath,"s0");
-            /* some CDs don't have a partition 0 */
-            fd = open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
-            if (fd < 0) {
-                bsdPath[strlen(bsdPath)-1] = '1';
-            } else {
-                close(fd);
-            }
-            filename = bsdPath;
-        }
-        
-        if ( mediaIterator )
-            IOObjectRelease( mediaIterator );
-    }
-#endif
     open_flags = O_BINARY;
     if ((flags & BDRV_O_ACCESS) == O_RDWR) {
         open_flags |= O_RDWR;
@@ -150,9 +92,15 @@ static int raw_open(BlockDriverState *bs, const char *filename, int flags)
     if (flags & BDRV_O_CREAT)
         open_flags |= O_CREAT | O_TRUNC;
+    s->type = FTYPE_FILE;
+
     fd = open(filename, open_flags, 0644);
-    if (fd < 0)
-        return -errno;
+    if (fd < 0) {
+        ret = -errno;
+        if (ret == -EROFS)
+            ret = -EACCES;
+        return ret;
+    }
     s->fd = fd;
     return 0;
 }
@@ -180,6 +128,10 @@ static int raw_pread(BlockDriverState *bs, int64_t offset,
     BDRVRawState *s = bs->opaque;
     int ret;
+    ret = fd_open(bs);
+    if (ret < 0)
+        return ret;
+
     lseek(s->fd, offset, SEEK_SET);
     ret = read(s->fd, buf, count);
     return ret;
@@ -191,13 +143,17 @@ static int raw_pwrite(BlockDriverState *bs, int64_t offset,
     BDRVRawState *s = bs->opaque;
     int ret;
+    ret = fd_open(bs);
+    if (ret < 0)
+        return ret;
+
     lseek(s->fd, offset, SEEK_SET);
     ret = write(s->fd, buf, count);
     return ret;
 }
 /***********************************************************/
-/* Unix AOP using POSIX AIO */
+/* Unix AIO using POSIX AIO */
 typedef struct RawAIOCB {
     BlockDriverAIOCB common;
@@ -236,15 +192,18 @@ void qemu_aio_init(void)
     act.sa_handler = aio_signal_handler;
     sigaction(aio_sig_num, &act, NULL);
+#if defined(__GLIBC__) && defined(__linux__)
     {
-        /* XXX: aio thread exit seems to hang on RH 9 */
+        /* XXX: aio thread exit seems to hang on RedHat 9 and this init
+           seems to fix the problem. */
         struct aioinit ai;
         memset(&ai, 0, sizeof(ai));
-        ai.aio_threads = 2;
+        ai.aio_threads = 1;
         ai.aio_num = 1;
         ai.aio_idle_time = 365 * 100000;
         aio_init(&ai);
     }
+#endif
 }
 void qemu_aio_poll(void)
@@ -270,7 +229,7 @@ void qemu_aio_poll(void)
                     if (ret == acb->aiocb.aio_nbytes)
                         ret = 0;
                     else
-                        ret = -1;
+                        ret = -EINVAL;
                 } else {
                     ret = -ret;
                 }
@@ -329,6 +288,9 @@ static RawAIOCB *raw_aio_setup(BlockDriverState *bs,
     BDRVRawState *s = bs->opaque;
     RawAIOCB *acb;
+    if (fd_open(bs) < 0)
+        return NULL;
+
     acb = qemu_aio_get(bs, cb, opaque);
     if (!acb)
         return NULL;
@@ -405,12 +367,17 @@ static void raw_aio_cancel(BlockDriverAIOCB *blockacb)
 static void raw_close(BlockDriverState *bs)
 {
     BDRVRawState *s = bs->opaque;
-    close(s->fd);
+    if (s->fd >= 0) {
+        close(s->fd);
+        s->fd = -1;
+    }
 }
 static int raw_truncate(BlockDriverState *bs, int64_t offset)
 {
     BDRVRawState *s = bs->opaque;
+    if (s->type != FTYPE_FILE)
+        return -ENOTSUP;
     if (ftruncate(s->fd, offset) < 0)
         return -errno;
     return 0;
@@ -428,6 +395,11 @@ static int64_t  raw_getlength(BlockDriverState *bs)
     struct dk_minfo minfo;
     int rv;
 #endif
+    int ret;
+
+    ret = fd_open(bs);
+    if (ret < 0)
+        return ret;
 #ifdef _BSD
     if (!fstat(fd, &sb) && (S_IFCHR & sb.st_mode)) {
@@ -455,12 +427,6 @@ static int64_t  raw_getlength(BlockDriverState *bs)
     {
         size = lseek(fd, 0, SEEK_END);
     }
-#ifdef _WIN32
-    /* On Windows hosts it can happen that we're unable to get file size
-       for CD-ROM raw device (it's inherent limitation of the CDFS driver). */
-    if (size == -1)
-        size = LONG_LONG_MAX;
-#endif
     return size;
 }
@@ -509,13 +475,358 @@ BlockDriver bdrv_raw = {
     .bdrv_getlength = raw_getlength,
 };
+/***********************************************/
+/* host device */
+
+#ifdef CONFIG_COCOA
+static kern_return_t FindEjectableCDMedia( io_iterator_t *mediaIterator );
+static kern_return_t GetBSDPath( io_iterator_t mediaIterator, char *bsdPath, CFIndex maxPathSize );
+
+kern_return_t FindEjectableCDMedia( io_iterator_t *mediaIterator )
+{
+    kern_return_t       kernResult; 
+    mach_port_t     masterPort;
+    CFMutableDictionaryRef  classesToMatch;
+
+    kernResult = IOMasterPort( MACH_PORT_NULL, &masterPort );
+    if ( KERN_SUCCESS != kernResult ) {
+        printf( "IOMasterPort returned %d\n", kernResult );
+    }
+    
+    classesToMatch = IOServiceMatching( kIOCDMediaClass ); 
+    if ( classesToMatch == NULL ) {
+        printf( "IOServiceMatching returned a NULL dictionary.\n" );
+    } else {
+    CFDictionarySetValue( classesToMatch, CFSTR( kIOMediaEjectableKey ), kCFBooleanTrue );
+    }
+    kernResult = IOServiceGetMatchingServices( masterPort, classesToMatch, mediaIterator );
+    if ( KERN_SUCCESS != kernResult )
+    {
+        printf( "IOServiceGetMatchingServices returned %d\n", kernResult );
+    }
+    
+    return kernResult;
+}
+
+kern_return_t GetBSDPath( io_iterator_t mediaIterator, char *bsdPath, CFIndex maxPathSize )
+{
+    io_object_t     nextMedia;
+    kern_return_t   kernResult = KERN_FAILURE;
+    *bsdPath = '\0';
+    nextMedia = IOIteratorNext( mediaIterator );
+    if ( nextMedia )
+    {
+        CFTypeRef   bsdPathAsCFString;
+    bsdPathAsCFString = IORegistryEntryCreateCFProperty( nextMedia, CFSTR( kIOBSDNameKey ), kCFAllocatorDefault, 0 );
+        if ( bsdPathAsCFString ) {
+            size_t devPathLength;
+            strcpy( bsdPath, _PATH_DEV );
+            strcat( bsdPath, "r" );
+            devPathLength = strlen( bsdPath );
+            if ( CFStringGetCString( bsdPathAsCFString, bsdPath + devPathLength, maxPathSize - devPathLength, kCFStringEncodingASCII ) ) {
+                kernResult = KERN_SUCCESS;
+            }
+            CFRelease( bsdPathAsCFString );
+        }
+        IOObjectRelease( nextMedia );
+    }
+    
+    return kernResult;
+}
+
+#endif
+
+static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
+{
+    BDRVRawState *s = bs->opaque;
+    int fd, open_flags, ret;
+
+#ifdef CONFIG_COCOA
+    if (strstart(filename, "/dev/cdrom", NULL)) {
+        kern_return_t kernResult;
+        io_iterator_t mediaIterator;
+        char bsdPath[ MAXPATHLEN ];
+        int fd;
+ 
+        kernResult = FindEjectableCDMedia( &mediaIterator );
+        kernResult = GetBSDPath( mediaIterator, bsdPath, sizeof( bsdPath ) );
+    
+        if ( bsdPath[ 0 ] != '\0' ) {
+            strcat(bsdPath,"s0");
+            /* some CDs don't have a partition 0 */
+            fd = open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
+            if (fd < 0) {
+                bsdPath[strlen(bsdPath)-1] = '1';
+            } else {
+                close(fd);
+            }
+            filename = bsdPath;
+        }
+        
+        if ( mediaIterator )
+            IOObjectRelease( mediaIterator );
+    }
+#endif
+    open_flags = O_BINARY;
+    if ((flags & BDRV_O_ACCESS) == O_RDWR) {
+        open_flags |= O_RDWR;
+    } else {
+        open_flags |= O_RDONLY;
+        bs->read_only = 1;
+    }
+
+    s->type = FTYPE_FILE;
+#if defined(__linux__)
+    if (strstart(filename, "/dev/cd", NULL)) {
+        /* open will not fail even if no CD is inserted */
+        open_flags |= O_NONBLOCK;
+        s->type = FTYPE_CD;
+    } else if (strstart(filename, "/dev/fd", NULL)) {
+        s->type = FTYPE_FD;
+        s->fd_open_flags = open_flags;
+        /* open will not fail even if no floppy is inserted */
+        open_flags |= O_NONBLOCK;
+    }
+#endif
+    fd = open(filename, open_flags, 0644);
+    if (fd < 0) {
+        ret = -errno;
+        if (ret == -EROFS)
+            ret = -EACCES;
+        return ret;
+    }
+    s->fd = fd;
+#if defined(__linux__)
+    /* close fd so that we can reopen it as needed */
+    if (s->type == FTYPE_FD) {
+        close(s->fd);
+        s->fd = -1;
+        s->fd_media_changed = 1;
+    }
+#endif
+    return 0;
+}
+
+#if defined(__linux__) && !defined(QEMU_TOOL)
+
+/* Note: we do not have a reliable method to detect if the floppy is
+   present. The current method is to try to open the floppy at every
+   I/O and to keep it opened during a few hundreds of ms. */
+static int fd_open(BlockDriverState *bs)
+{
+    BDRVRawState *s = bs->opaque;
+    int last_media_present;
+
+    if (s->type != FTYPE_FD)
+        return 0;
+    last_media_present = (s->fd >= 0);
+    if (s->fd >= 0 && 
+        (qemu_get_clock(rt_clock) - s->fd_open_time) >= FD_OPEN_TIMEOUT) {
+        close(s->fd);
+        s->fd = -1;
+#ifdef DEBUG_FLOPPY
+        printf("Floppy closed\n");
+#endif
+    }
+    if (s->fd < 0) {
+        if (s->fd_got_error && 
+            (qemu_get_clock(rt_clock) - s->fd_error_time) < FD_OPEN_TIMEOUT) {
+#ifdef DEBUG_FLOPPY
+            printf("No floppy (open delayed)\n");
+#endif
+            return -EIO;
+        }
+        s->fd = open(bs->filename, s->fd_open_flags);
+        if (s->fd < 0) {
+            s->fd_error_time = qemu_get_clock(rt_clock);
+            s->fd_got_error = 1;
+            if (last_media_present)
+                s->fd_media_changed = 1;
+#ifdef DEBUG_FLOPPY
+            printf("No floppy\n");
+#endif
+            return -EIO;
+        }
+#ifdef DEBUG_FLOPPY
+        printf("Floppy opened\n");
+#endif
+    }
+    if (!last_media_present)
+        s->fd_media_changed = 1;
+    s->fd_open_time = qemu_get_clock(rt_clock);
+    s->fd_got_error = 0;
+    return 0;
+}
+#else
+static int fd_open(BlockDriverState *bs)
+{
+    return 0;
+}
+#endif
+
+#if defined(__linux__)
+
+static int raw_is_inserted(BlockDriverState *bs)
+{
+    BDRVRawState *s = bs->opaque;
+    int ret;
+
+    switch(s->type) {
+    case FTYPE_CD:
+        ret = ioctl(s->fd, CDROM_DRIVE_STATUS, CDSL_CURRENT);
+        if (ret == CDS_DISC_OK)
+            return 1;
+        else
+            return 0;
+        break;
+    case FTYPE_FD:
+        ret = fd_open(bs);
+        return (ret >= 0);
+    default:
+        return 1;
+    }
+}
+
+/* currently only used by fdc.c, but a CD version would be good too */
+static int raw_media_changed(BlockDriverState *bs)
+{
+    BDRVRawState *s = bs->opaque;
+
+    switch(s->type) {
+    case FTYPE_FD:
+        {
+            int ret;
+            /* XXX: we do not have a true media changed indication. It
+               does not work if the floppy is changed without trying
+               to read it */
+            fd_open(bs);
+            ret = s->fd_media_changed;
+            s->fd_media_changed = 0;
+#ifdef DEBUG_FLOPPY
+            printf("Floppy changed=%d\n", ret);
+#endif
+            return ret;
+        }
+    default:
+        return -ENOTSUP;
+    }
+}
+
+static int raw_eject(BlockDriverState *bs, int eject_flag)
+{
+    BDRVRawState *s = bs->opaque;
+
+    switch(s->type) {
+    case FTYPE_CD:
+        if (eject_flag) {
+            if (ioctl (s->fd, CDROMEJECT, NULL) < 0)
+                perror("CDROMEJECT");
+        } else {
+            if (ioctl (s->fd, CDROMCLOSETRAY, NULL) < 0)
+                perror("CDROMEJECT");
+        }
+        break;
+    case FTYPE_FD:
+        {
+            int fd;
+            if (s->fd >= 0) {
+                close(s->fd);
+                s->fd = -1;
+            }
+            fd = open(bs->filename, s->fd_open_flags | O_NONBLOCK);
+            if (fd >= 0) {
+                if (ioctl(fd, FDEJECT, 0) < 0)
+                    perror("FDEJECT");
+                close(fd);
+            }
+        }
+        break;
+    default:
+        return -ENOTSUP;
+    }
+    return 0;
+}
+
+static int raw_set_locked(BlockDriverState *bs, int locked)
+{
+    BDRVRawState *s = bs->opaque;
+
+    switch(s->type) {
+    case FTYPE_CD:
+        if (ioctl (s->fd, CDROM_LOCKDOOR, locked) < 0) {
+            /* Note: an error can happen if the distribution automatically
+               mounts the CD-ROM */
+            //        perror("CDROM_LOCKDOOR");
+        }
+        break;
+    default:
+        return -ENOTSUP;
+    }
+    return 0;
+}
+
+#else
+
+static int raw_is_inserted(BlockDriverState *bs)
+{
+    return 1;
+}
+
+static int raw_media_changed(BlockDriverState *bs)
+{
+    return -ENOTSUP;
+}
+
+static int raw_eject(BlockDriverState *bs, int eject_flag)
+{
+    return -ENOTSUP;
+}
+
+static int raw_set_locked(BlockDriverState *bs, int locked)
+{
+    return -ENOTSUP;
+}
+
+#endif /* !linux */
+
+BlockDriver bdrv_host_device = {
+    "host_device",
+    sizeof(BDRVRawState),
+    NULL, /* no probe for protocols */
+    hdev_open,
+    NULL,
+    NULL,
+    raw_close,
+    NULL,
+    raw_flush,
+    
+    .bdrv_aio_read = raw_aio_read,
+    .bdrv_aio_write = raw_aio_write,
+    .bdrv_aio_cancel = raw_aio_cancel,
+    .aiocb_size = sizeof(RawAIOCB),
+    .bdrv_pread = raw_pread,
+    .bdrv_pwrite = raw_pwrite,
+    .bdrv_getlength = raw_getlength,
+
+    /* removable device support */
+    .bdrv_is_inserted = raw_is_inserted,
+    .bdrv_media_changed = raw_media_changed,
+    .bdrv_eject = raw_eject,
+    .bdrv_set_locked = raw_set_locked,
+};
+
 #else /* _WIN32 */
 /* XXX: use another file ? */
 #include <winioctl.h>
+#define FTYPE_FILE 0
+#define FTYPE_CD     1
+
 typedef struct BDRVRawState {
     HANDLE hfile;
+    int type;
+    char drive_letter[2];
 } BDRVRawState;
 typedef struct RawAIOCB {
@@ -565,6 +876,23 @@ static int raw_open(BlockDriverState *bs, const char *filename, int flags)
     BDRVRawState *s = bs->opaque;
     int access_flags, create_flags;
     DWORD overlapped;
+    char device_name[64];
+    const char *p;
+
+    if (strstart(filename, "/dev/cdrom", NULL)) {
+        if (find_cdrom(device_name, sizeof(device_name)) < 0)
+            return -ENOENT;
+        filename = device_name;
+    } else {
+        /* transform drive letters into device name */
+        if (((filename[0] >= 'a' && filename[0] <= 'z') ||
+             (filename[0] >= 'A' && filename[0] <= 'Z')) &&
+            filename[1] == ':' && filename[2] == '\0') {
+            snprintf(device_name, sizeof(device_name), "\\\\.\\%c:", filename[0]);
+            filename = device_name;
+        }
+    }
+    s->type = find_device_type(filename);
     if ((flags & BDRV_O_ACCESS) == O_RDWR) {
         access_flags = GENERIC_READ | GENERIC_WRITE;
@@ -765,10 +1093,22 @@ static int64_t  raw_getlength(BlockDriverState *bs)
 {
     BDRVRawState *s = bs->opaque;
     LARGE_INTEGER l;
+    ULARGE_INTEGER available, total, total_free; 
-    l.LowPart = GetFileSize(s->hfile, &l.HighPart);
-    if (l.LowPart == 0xffffffffUL && GetLastError() != NO_ERROR)
-	return -EIO;
+    switch(s->ftype) {
+    case FTYPE_FILE:
+        l.LowPart = GetFileSize(s->hfile, &l.HighPart);
+        if (l.LowPart == 0xffffffffUL && GetLastError() != NO_ERROR)
+            return -EIO;
+        break;
+    case FTYPE_CD:
+        if (!GetDiskFreeSpaceEx(s->drive_letter, &available, &total, &total_free))
+            return -EIO;
+        l = total;
+        break;
+    default:
+        return -EIO;
+    }
     return l.QuadPart;
 }
@@ -833,4 +1173,146 @@ BlockDriver bdrv_raw = {
     .bdrv_truncate = raw_truncate,
     .bdrv_getlength = raw_getlength,
 };
+
+/***********************************************/
+/* host device */
+
+static int find_cdrom(char *cdrom_name, int cdrom_name_size)
+{
+    char drives[256], *pdrv = drives;
+    UINT type;
+
+    memset(drives, 0, sizeof(drivers));
+    GetLogicalDriveStrings(sizeof(drives), drives);
+    while(pdrv[0] != '\0') {
+        type = GetDriveType(pdrv);
+        switch(type) {
+        case DRIVE_CDROM:
+            snprintf(cdrom_name, cdrom_name_size, "\\\\.\\%c:", pdrv[0]);
+            return 0;
+            break;
+        }
+        pdrv += lstrlen(pdrv) + 1;
+    }
+    return -1;
+}
+
+static int find_device_type(const char *filename)
+{
+    UINT type;
+    const char *p;
+
+    if (strstart(filename, "\\\\.\\", &p) ||
+        strstart(filename, "//./", &p)) {
+        s->drive_letter[0] = p[0];
+        s->drive_letter[1] = '\0';
+        type = GetDriveType(s->drive_letter);
+        if (type == DRIVE_CDROM)
+            return FTYPE_CD;
+        else
+            return FTYPE_FILE;
+    } else {
+        return FTYPE_FILE;
+    }
+}
+
+static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
+{
+    BDRVRawState *s = bs->opaque;
+    int access_flags, create_flags;
+    DWORD overlapped;
+    char device_name[64];
+    const char *p;
+
+    if (strstart(filename, "/dev/cdrom", NULL)) {
+        if (find_cdrom(device_name, sizeof(device_name)) < 0)
+            return -ENOENT;
+        filename = device_name;
+    } else {
+        /* transform drive letters into device name */
+        if (((filename[0] >= 'a' && filename[0] <= 'z') ||
+             (filename[0] >= 'A' && filename[0] <= 'Z')) &&
+            filename[1] == ':' && filename[2] == '\0') {
+            snprintf(device_name, sizeof(device_name), "\\\\.\\%c:", filename[0]);
+            filename = device_name;
+        }
+    }
+    s->type = find_device_type(filename);
+
+    if ((flags & BDRV_O_ACCESS) == O_RDWR) {
+        access_flags = GENERIC_READ | GENERIC_WRITE;
+    } else {
+        access_flags = GENERIC_READ;
+    }
+    create_flags = OPEN_EXISTING;
+
+#ifdef QEMU_TOOL
+    overlapped = 0;
+#else
+    overlapped = FILE_FLAG_OVERLAPPED;
+#endif
+    s->hfile = CreateFile(filename, access_flags, 
+                          FILE_SHARE_READ, NULL,
+                          create_flags, overlapped, 0);
+    if (s->hfile == INVALID_HANDLE_VALUE) 
+        return -1;
+    return 0;
+}
+
+#if 0
+/***********************************************/
+/* removable device additionnal commands */
+
+static int raw_is_inserted(BlockDriverState *bs)
+{
+    return 1;
+}
+
+static int raw_media_changed(BlockDriverState *bs)
+{
+    return -ENOTSUP;
+}
+
+static int raw_eject(BlockDriverState *bs, int eject_flag)
+{
+    DWORD ret_count;
+
+    if (s->type == FTYPE_FILE)
+        return -ENOTSUP;
+    if (eject_flag) {
+        DeviceIoControl(s->hfile, IOCTL_STORAGE_EJECT_MEDIA, 
+                        NULL, 0, NULL, 0, &lpBytesReturned, NULL);
+    } else {
+        DeviceIoControl(s->hfile, IOCTL_STORAGE_LOAD_MEDIA, 
+                        NULL, 0, NULL, 0, &lpBytesReturned, NULL);
+    }
+}
+
+static int raw_set_locked(BlockDriverState *bs, int locked)
+{
+    return -ENOTSUP;
+}
+#endif
+
+BlockDriver bdrv_host_device = {
+    "host_device",
+    sizeof(BDRVRawState),
+    NULL, /* no probe for protocols */
+    hdev_open,
+    NULL,
+    NULL,
+    raw_close,
+    NULL,
+    raw_flush,
+    
+#if 0
+    .bdrv_aio_read = raw_aio_read,
+    .bdrv_aio_write = raw_aio_write,
+    .bdrv_aio_cancel = raw_aio_cancel,
+    .aiocb_size = sizeof(RawAIOCB);
+#endif
+    .bdrv_pread = raw_pread,
+    .bdrv_pwrite = raw_pwrite,
+    .bdrv_getlength = raw_getlength,
+};
 #endif /* _WIN32 */
@@ -181,24 +181,37 @@ void get_tmp_filename(char *filename, int size)
 }
 #endif
+#ifdef _WIN32
+static int is_windows_drive(const char *filename)
+{
+    if (((filename[0] >= 'a' && filename[0] <= 'z') ||
+         (filename[0] >= 'A' && filename[0] <= 'Z')) &&
+        filename[1] == ':' && 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))
+        return &bdrv_raw;
+#endif
     p = strchr(filename, ':');
     if (!p)
         return &bdrv_raw;
     len = p - filename;
     if (len > sizeof(protocol) - 1)
         len = sizeof(protocol) - 1;
-#ifdef _WIN32
-    if (len == 1) {
-        /* specific win32 case for driver letters */
-        return &bdrv_raw;
-    }
-#endif   
     memcpy(protocol, filename, len);
     protocol[len] = '\0';
     for(drv1 = first_drv; drv1 != NULL; drv1 = drv1->next) {
@@ -218,14 +231,28 @@ static BlockDriver *find_image_format(const char *filename)
     uint8_t buf[2048];
     BlockDriverState *bs;
+    /* detect host devices. By convention, /dev/cdrom[N] is always
+       recognized as a host CDROM */
+    if (strstart(filename, "/dev/cdrom", NULL))
+        return &bdrv_host_device;
+#ifdef _WIN32
+    if (is_windows_drive(filename))
+        return &bdrv_host_device;
+#else
+    {
+        struct stat st;
+        if (stat(filename, &st) >= 0 && 
+            (S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode))) {
+            return &bdrv_host_device;
+        }
+    }
+#endif
+    
     drv = find_protocol(filename);
-    /* no need to test disk image formats for vvfat or host specific
-       devices */
+    /* no need to test disk image formats for vvfat */
     if (drv == &bdrv_vvfat)
         return drv;
-    if (strstart(filename, "/dev/", NULL))
-        return &bdrv_raw;
-    
+
     ret = bdrv_file_open(&bs, filename, BDRV_O_RDONLY);
     if (ret < 0)
         return NULL;
@@ -362,9 +389,8 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags,
             goto fail;
     }
-    bs->inserted = 1;
-
     /* call the change callback */
+    bs->media_changed = 1;
     if (bs->change_cb)
         bs->change_cb(bs->change_opaque);
@@ -373,7 +399,7 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags,
 void bdrv_close(BlockDriverState *bs)
 {
-    if (bs->inserted) {
+    if (bs->drv) {
         if (bs->backing_hd)
             bdrv_delete(bs->backing_hd);
         bs->drv->bdrv_close(bs);
@@ -385,9 +411,9 @@ void bdrv_close(BlockDriverState *bs)
 #endif
         bs->opaque = NULL;
         bs->drv = NULL;
-        bs->inserted = 0;
         /* call the change callback */
+        bs->media_changed = 1;
         if (bs->change_cb)
             bs->change_cb(bs->change_opaque);
     }
@@ -403,12 +429,13 @@ void bdrv_delete(BlockDriverState *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;
     unsigned char sector[512];
-    if (!bs->inserted)
-        return -ENOENT;
+    if (!drv)
+        return -ENOMEDIUM;
     if (bs->read_only) {
 	return -EACCES;
@@ -420,7 +447,7 @@ int bdrv_commit(BlockDriverState *bs)
     total_sectors = bdrv_getlength(bs) >> SECTOR_BITS;
     for (i = 0; i < total_sectors;) {
-        if (bs->drv->bdrv_is_allocated(bs, i, 65536, &n)) {
+        if (drv->bdrv_is_allocated(bs, i, 65536, &n)) {
             for(j = 0; j < n; j++) {
                 if (bdrv_read(bs, i, sector, 1) != 0) {
                     return -EIO;
@@ -436,20 +463,20 @@ int bdrv_commit(BlockDriverState *bs)
         }
     }
-    if (bs->drv->bdrv_make_empty)
-	return bs->drv->bdrv_make_empty(bs);
+    if (drv->bdrv_make_empty)
+	return drv->bdrv_make_empty(bs);
     return 0;
 }
-/* return < 0 if error */
+/* 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 (!bs->inserted)
-        return -1;
+    if (!drv)
+        return -ENOMEDIUM;
     if (sector_num == 0 && bs->boot_sector_enabled && nb_sectors > 0) {
             memcpy(buf, bs->boot_sector_data, 512);
@@ -466,7 +493,7 @@ int bdrv_read(BlockDriverState *bs, int64_t sector_num,
         if (ret < 0)
             return ret;
         else if (ret != len)
-            return -EIO;
+            return -EINVAL;
         else
             return 0;
     } else {
@@ -474,15 +501,20 @@ int bdrv_read(BlockDriverState *bs, int64_t sector_num,
     }
 }
-/* return < 0 if error */
+/* 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->inserted)
-        return -1;
+    if (!bs->drv)
+        return -ENOMEDIUM;
     if (bs->read_only)
-        return -1;
+        return -EACCES;
     if (sector_num == 0 && bs->boot_sector_enabled && nb_sectors > 0) {
         memcpy(bs->boot_sector_data, buf, 512);   
     }
@@ -501,7 +533,6 @@ int bdrv_write(BlockDriverState *bs, int64_t sector_num,
     }
 }
-/* not necessary now */
 static int bdrv_pread_em(BlockDriverState *bs, int64_t offset, 
                          uint8_t *buf, int count1)
 {
@@ -603,7 +634,7 @@ int bdrv_pread(BlockDriverState *bs, int64_t offset,
     BlockDriver *drv = bs->drv;
     if (!drv)
-        return -ENOENT;
+        return -ENOMEDIUM;
     if (!drv->bdrv_pread)
         return bdrv_pread_em(bs, offset, buf1, count1);
     return drv->bdrv_pread(bs, offset, buf1, count1);
@@ -618,7 +649,7 @@ int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
     BlockDriver *drv = bs->drv;
     if (!drv)
-        return -ENOENT;
+        return -ENOMEDIUM;
     if (!drv->bdrv_pwrite)
         return bdrv_pwrite_em(bs, offset, buf1, count1);
     return drv->bdrv_pwrite(bs, offset, buf1, count1);
@@ -631,7 +662,7 @@ int bdrv_truncate(BlockDriverState *bs, int64_t offset)
 {
     BlockDriver *drv = bs->drv;
     if (!drv)
-        return -ENOENT;
+        return -ENOMEDIUM;
     if (!drv->bdrv_truncate)
         return -ENOTSUP;
     return drv->bdrv_truncate(bs, offset);
@@ -644,7 +675,7 @@ int64_t bdrv_getlength(BlockDriverState *bs)
 {
     BlockDriver *drv = bs->drv;
     if (!drv)
-        return -ENOENT;
+        return -ENOMEDIUM;
     if (!drv->bdrv_getlength) {
         /* legacy mode */
         return bs->total_sectors * SECTOR_SIZE;
@@ -652,9 +683,16 @@ int64_t bdrv_getlength(BlockDriverState *bs)
     return drv->bdrv_getlength(bs);
 }
+/* return 0 as number of sectors if no device present or error */
 void bdrv_get_geometry(BlockDriverState *bs, int64_t *nb_sectors_ptr)
 {
-    *nb_sectors_ptr = bs->total_sectors;
+    int64_t length;
+    length = bdrv_getlength(bs);
+    if (length < 0)
+        length = 0;
+    else
+        length = length >> SECTOR_BITS;
+    *nb_sectors_ptr = length;
 }
 /* force a given boot sector. */
@@ -715,21 +753,7 @@ 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;
-}
-
+/* XXX: no longer used */
 void bdrv_set_change_cb(BlockDriverState *bs, 
                         void (*change_cb)(void *opaque), void *opaque)
 {
@@ -761,7 +785,7 @@ int bdrv_set_key(BlockDriverState *bs, const char *key)
 void bdrv_get_format(BlockDriverState *bs, char *buf, int buf_size)
 {
-    if (!bs->inserted || !bs->drv) {
+    if (!bs->drv) {
         buf[0] = '\0';
     } else {
         pstrcpy(buf, buf_size, bs->drv->format_name);
@@ -833,7 +857,7 @@ void bdrv_info(void)
         if (bs->removable) {
             term_printf(" locked=%d", bs->locked);
         }
-        if (bs->inserted) {
+        if (bs->drv) {
             term_printf(" file=%s", bs->filename);
             if (bs->backing_file[0] != '\0')
                 term_printf(" backing_file=%s", bs->backing_file);
@@ -863,7 +887,7 @@ int bdrv_write_compressed(BlockDriverState *bs, int64_t sector_num,
 {
     BlockDriver *drv = bs->drv;
     if (!drv)
-        return -ENOENT;
+        return -ENOMEDIUM;
     if (!drv->bdrv_write_compressed)
         return -ENOTSUP;
     return drv->bdrv_write_compressed(bs, sector_num, buf, nb_sectors);
@@ -873,7 +897,7 @@ int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 {
     BlockDriver *drv = bs->drv;
     if (!drv)
-        return -ENOENT;
+        return -ENOMEDIUM;
     if (!drv->bdrv_get_info)
         return -ENOTSUP;
     memset(bdi, 0, sizeof(*bdi));
@@ -888,7 +912,7 @@ int bdrv_snapshot_create(BlockDriverState *bs,
 {
     BlockDriver *drv = bs->drv;
     if (!drv)
-        return -ENOENT;
+        return -ENOMEDIUM;
     if (!drv->bdrv_snapshot_create)
         return -ENOTSUP;
     return drv->bdrv_snapshot_create(bs, sn_info);
@@ -899,7 +923,7 @@ int bdrv_snapshot_goto(BlockDriverState *bs,
 {
     BlockDriver *drv = bs->drv;
     if (!drv)
-        return -ENOENT;
+        return -ENOMEDIUM;
     if (!drv->bdrv_snapshot_goto)
         return -ENOTSUP;
     return drv->bdrv_snapshot_goto(bs, snapshot_id);
@@ -909,7 +933,7 @@ int bdrv_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
 {
     BlockDriver *drv = bs->drv;
     if (!drv)
-        return -ENOENT;
+        return -ENOMEDIUM;
     if (!drv->bdrv_snapshot_delete)
         return -ENOTSUP;
     return drv->bdrv_snapshot_delete(bs, snapshot_id);
@@ -920,7 +944,7 @@ int bdrv_snapshot_list(BlockDriverState *bs,
 {
     BlockDriver *drv = bs->drv;
     if (!drv)
-        return -ENOENT;
+        return -ENOMEDIUM;
     if (!drv->bdrv_snapshot_list)
         return -ENOTSUP;
     return drv->bdrv_snapshot_list(bs, psn_info);
@@ -1001,7 +1025,7 @@ BlockDriverAIOCB *bdrv_aio_read(BlockDriverState *bs, int64_t sector_num,
 {
     BlockDriver *drv = bs->drv;
-    if (!bs->inserted)
+    if (!drv)
         return NULL;
     /* XXX: we assume that nb_sectors == 0 is suppored by the async read */
@@ -1021,7 +1045,7 @@ BlockDriverAIOCB *bdrv_aio_write(BlockDriverState *bs, int64_t sector_num,
 {
     BlockDriver *drv = bs->drv;
-    if (!bs->inserted)
+    if (!drv)
         return NULL;
     if (bs->read_only)
         return NULL;
@@ -1170,6 +1194,7 @@ static int bdrv_write_em(BlockDriverState *bs, int64_t sector_num,
 void bdrv_init(void)
 {
     bdrv_register(&bdrv_raw);
+    bdrv_register(&bdrv_host_device);
 #ifndef _WIN32
     bdrv_register(&bdrv_cow);
 #endif
@@ -1211,3 +1236,78 @@ void qemu_aio_release(void *p)
     acb->next = drv->free_aiocb;
     drv->free_aiocb = acb;
 }
+
+/**************************************************************/
+/* removable device support */
+
+/**
+ * Return TRUE if the media is present
+ */
+int bdrv_is_inserted(BlockDriverState *bs)
+{
+    BlockDriver *drv = bs->drv;
+    int ret;
+    if (!drv)
+        return 0;
+    if (!drv->bdrv_is_inserted)
+        return 1;
+    ret = drv->bdrv_is_inserted(bs);
+    return ret;
+}
+
+/**
+ * Return TRUE if the media changed since the last call to this
+ * function. It is currently only used for floppy disks 
+ */
+int bdrv_media_changed(BlockDriverState *bs)
+{
+    BlockDriver *drv = bs->drv;
+    int ret;
+
+    if (!drv || !drv->bdrv_media_changed)
+        ret = -ENOTSUP;
+    else
+        ret = drv->bdrv_media_changed(bs);
+    if (ret == -ENOTSUP)
+        ret = bs->media_changed;
+    bs->media_changed = 0;
+    return ret;
+}
+
+/**
+ * If eject_flag is TRUE, eject the media. Otherwise, close the tray
+ */
+void bdrv_eject(BlockDriverState *bs, int eject_flag)
+{
+    BlockDriver *drv = bs->drv;
+    int ret;
+
+    if (!drv || !drv->bdrv_eject) {
+        ret = -ENOTSUP;
+    } else {
+        ret = drv->bdrv_eject(bs, eject_flag);
+    }
+    if (ret == -ENOTSUP) {
+        if (eject_flag)
+            bdrv_close(bs);
+    }
+}
+
+int bdrv_is_locked(BlockDriverState *bs)
+{
+    return bs->locked;
+}
+
+/**
+ * Lock or unlock the media (if it is locked, the user won't be able
+ * to eject it manually).
+ */
+void bdrv_set_locked(BlockDriverState *bs, int locked)
+{
+    BlockDriver *drv = bs->drv;
+
+    bs->locked = locked;
+    if (drv && drv->bdrv_set_locked) {
+        drv->bdrv_set_locked(bs, locked);
+    }
+}
@@ -70,6 +70,12 @@ struct BlockDriver {
                               QEMUSnapshotInfo **psn_info);
     int (*bdrv_get_info)(BlockDriverState *bs, BlockDriverInfo *bdi);
+    /* removable device specific */
+    int (*bdrv_is_inserted)(BlockDriverState *bs);
+    int (*bdrv_media_changed)(BlockDriverState *bs);
+    int (*bdrv_eject)(BlockDriverState *bs, int eject_flag);
+    int (*bdrv_set_locked)(BlockDriverState *bs, int locked);
+    
     BlockDriverAIOCB *free_aiocb;
     struct BlockDriver *next;
 };
@@ -78,7 +84,6 @@ struct BlockDriverState {
     int64_t total_sectors; /* if we are reading a disk image, give its
                               size in sectors */
     int read_only; /* if true, the media is read only */
-    int inserted; /* if true, the media is present */
     int removable; /* if true, the media can be removed */
     int locked;    /* if true, the media cannot temporarily be ejected */
     int encrypted; /* if true, the media is encrypted */
@@ -86,7 +91,7 @@ struct BlockDriverState {
     void (*change_cb)(void *opaque);
     void *change_opaque;
-    BlockDriver *drv;
+    BlockDriver *drv; /* NULL means no media */
     void *opaque;
     int boot_sector_enabled;
@@ -96,7 +101,8 @@ struct BlockDriverState {
     char backing_file[1024]; /* if non zero, the image is a diff of
                                 this file image */
     int is_temporary;
-    
+    int media_changed;
+
     BlockDriverState *backing_hd;
     /* async read/write emulation */
@@ -206,7 +206,7 @@ Select the emulated machine (@code{-M ?} for list)
 @item -fda file
 @item -fdb file
 Use @var{file} as floppy disk 0/1 image (@pxref{disk_images}). You can
-use the host floppy by using @file{/dev/fd0} as filename.
+use the host floppy by using @file{/dev/fd0} as filename (@pxref{host_drives}).
 @item -hda file
 @item -hdb file
@@ -217,7 +217,7 @@ Use @var{file} as hard disk 0, 1, 2 or 3 image (@pxref{disk_images}).
 @item -cdrom file
 Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and and
 @option{-cdrom} at the same time). You can use the host CD-ROM by
-using @file{/dev/cdrom} as filename.
+using @file{/dev/cdrom} as filename (@pxref{host_drives}).
 @item -boot [a|c|d]
 Boot on floppy (a), hard disk (c) or CD-ROM (d). Hard disk boot is
@@ -916,6 +916,7 @@ snapshots.
 * disk_images_snapshot_mode:: Snapshot mode
 * vm_snapshots::              VM snapshots
 * qemu_img_invocation::       qemu-img Invocation
+* host_drives::               Using host drives
 * disk_images_fat_images::    Virtual FAT disk images
 @end menu
@@ -997,6 +998,57 @@ state is not saved or restored properly (in particular USB).
 @include qemu-img.texi
+@node host_drives
+@subsection Using host drives
+
+In addition to disk image files, QEMU can directly access host
+devices. We describe here the usage for QEMU version >= 0.8.3.
+
+@subsubsection Linux
+
+On Linux, you can directly use the host device filename instead of a
+disk image filename provided you have enough proviledge to access
+it. For example, use @file{/dev/cdrom} to access to the CDROM or
+@file{/dev/fd0} for the floppy.
+
+@table
+@item CD
+You can specify a CDROM device even if no CDROM is loaded. QEMU has
+specific code to detect CDROM insertion or removal. CDROM ejection by
+the guest OS is supported. Currently only data CDs are supported.
+@item Floppy
+You can specify a floppy device even if no floppy is loaded. Floppy
+removal is currently not detected accurately (if you change floppy
+without doing floppy access while the floppy is not loaded, the guest
+OS will think that the same floppy is loaded).
+@item Hard disks
+Hard disks can be used. Normally you must specify the whole disk
+(@file{/dev/hdb} instead of @file{/dev/hdb1}) so that the guest OS can
+see it as a partitioned disk. WARNING: unless you know what you do, it
+is better to only make READ-ONLY accesses to the hard disk otherwise
+you may corrupt your host data (use the @option{-snapshot} command
+line option or modify the device permissions accordingly).
+@end table
+
+@subsubsection Windows
+
+On Windows you can use any host drives as QEMU drive. The prefered
+syntax is the driver letter (e.g. @file{d:}). The alternate syntax
+@file{\\.\d:} is supported. @file{/dev/cdrom} is supported as an alias
+to the first CDROM drive.
+
+Currently there is no specific code to handle removable medias, so it
+is better to use the @code{change} or @code{eject} monitor commands to
+change or eject media.
+
+@subsubsection Mac OS X
+
+@file{/dev/cdrom} is an alias to the first CDROM. 
+
+Currently there is no specific code to handle removable medias, so it
+is better to use the @code{change} or @code{eject} monitor commands to
+change or eject media.
+
 @node disk_images_fat_images
 @subsection Virtual FAT disk images
@@ -50,6 +50,7 @@
 #define fsync _commit
 #define lseek _lseeki64
 #define ENOTSUP 4096
+#define ENOMEDIUM 4097
 extern int qemu_ftruncate64(int, int64_t);
 #define ftruncate qemu_ftruncate64
@@ -502,6 +503,7 @@ typedef struct BlockDriverState BlockDriverState;
 typedef struct BlockDriver BlockDriver;
 extern BlockDriver bdrv_raw;
+extern BlockDriver bdrv_host_device;
 extern BlockDriver bdrv_cow;
 extern BlockDriver bdrv_qcow;
 extern BlockDriver bdrv_vmdk;
@@ -604,8 +606,10 @@ int bdrv_get_translation_hint(BlockDriverState *bs);
 int bdrv_is_removable(BlockDriverState *bs);
 int bdrv_is_read_only(BlockDriverState *bs);
 int bdrv_is_inserted(BlockDriverState *bs);
+int bdrv_media_changed(BlockDriverState *bs);
 int bdrv_is_locked(BlockDriverState *bs);
 void bdrv_set_locked(BlockDriverState *bs, int locked);
+void bdrv_eject(BlockDriverState *bs, int eject_flag);
 void bdrv_set_change_cb(BlockDriverState *bs, 
                         void (*change_cb)(void *opaque), void *opaque);
 void bdrv_get_format(BlockDriverState *bs, char *buf, int buf_size);