[Qemu-devel] [PATCH v2] raw-posix.c: Make physical devices usable in QEMU under Mac OS X host

[Programmingkid <programmingkidx@gmail.com>]

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Mac OS X can be picky when it comes to allowing the user to use physical devices
in QEMU. This patch fixes that issue by testing each physical device first
before using it in QEMU. If an issue is detected, a message is displayed
showing the user how to unmount a volume. 

Signed-off-by: John Arbuckle <programmingkidx@gmail.com>

---
Removed volume unmounting code.
Removed automatic remounting code.
Displays helpful error message in place of remounting code.

 block/raw-posix.c |  115 ++++++++++++++++++++++++++++++++++++++++------------
 1 files changed, 88 insertions(+), 27 deletions(-)

diff --git a/block/raw-posix.c b/block/raw-posix.c
index cbe6574..9de37ea 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -42,9 +42,8 @@
 #include <IOKit/storage/IOMediaBSDClient.h>
 #include <IOKit/storage/IOMedia.h>
 #include <IOKit/storage/IOCDMedia.h>
-//#include <IOKit/storage/IOCDTypes.h>
 #include <CoreFoundation/CoreFoundation.h>
-#endif
+#endif /* (__APPLE__) && (__MACH__) */
 
 #ifdef __sun__
 #define _POSIX_PTHREAD_SEMANTICS 1
@@ -1972,8 +1971,9 @@ BlockDriver bdrv_file = {
 /* host device */
 
 #if defined(__APPLE__) && defined(__MACH__)
-static kern_return_t FindEjectableCDMedia( io_iterator_t *mediaIterator );
-static kern_return_t GetBSDPath( io_iterator_t mediaIterator, char *bsdPath, CFIndex maxPathSize );
+static kern_return_t FindEjectableCDMedia(io_iterator_t *mediaIterator);
+static kern_return_t GetBSDPath(io_iterator_t mediaIterator, char *bsdPath,
+                                CFIndex maxPathSize, int flags);
 
 kern_return_t FindEjectableCDMedia( io_iterator_t *mediaIterator )
 {
@@ -2001,7 +2001,8 @@ kern_return_t FindEjectableCDMedia( io_iterator_t *mediaIterator )
     return kernResult;
 }
 
-kern_return_t GetBSDPath( io_iterator_t mediaIterator, char *bsdPath, CFIndex maxPathSize )
+kern_return_t GetBSDPath(io_iterator_t mediaIterator, char *bsdPath,
+                         CFIndex maxPathSize, int flags)
 {
     io_object_t     nextMedia;
     kern_return_t   kernResult = KERN_FAILURE;
@@ -2014,7 +2015,9 @@ kern_return_t GetBSDPath( io_iterator_t mediaIterator, char *bsdPath, CFIndex ma
         if ( bsdPathAsCFString ) {
             size_t devPathLength;
             strcpy( bsdPath, _PATH_DEV );
-            strcat( bsdPath, "r" );
+            if (flags & BDRV_O_NOCACHE) {
+                strcat(bsdPath, "r");
+            }
             devPathLength = strlen( bsdPath );
             if ( CFStringGetCString( bsdPathAsCFString, bsdPath + devPathLength, maxPathSize - devPathLength, kCFStringEncodingASCII ) ) {
                 kernResult = KERN_SUCCESS;
@@ -2027,7 +2030,67 @@ kern_return_t GetBSDPath( io_iterator_t mediaIterator, char *bsdPath, CFIndex ma
     return kernResult;
 }
 
-#endif
+/* Sets up a physical device for use in QEMU */
+static void setupDevice(const char *bsdPath)
+{
+   /*
+    * Mac OS X does not like allowing QEMU to use physical devices that are
+    * mounted. Attempts to do so result in 'Resource busy' errors.
+    */
+
+    int fd;
+    fd = qemu_open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
+
+    /* if the device fails to open */
+    if (fd < 0) {
+        printf("Error: failed to open %s\n", bsdPath);
+        printf("If device %s is mounted on the desktop, unmount it"
+               " first before using it in QEMU.\n", bsdPath);
+        printf("\nCommand to unmount device: diskutil unmountDisk %s", bsdPath);
+        printf("\nCommand to mount device: diskutil mountDisk %s\n\n", bsdPath);
+    }
+
+    /* if the device opens */
+    else {
+        qemu_close(fd);
+    }
+}
+
+/* Sets up a real cdrom for use in QEMU */
+static void setupCDROM(char *bsdPath)
+{
+    int index, numOfTestPartitions = 2, fd;
+    char testPartition[MAXPATHLEN];
+    bool partitionFound = false;
+
+    /* look for a working partition */
+    for (index = 0; index < numOfTestPartitions; index++) {
+        strncpy(testPartition, bsdPath, MAXPATHLEN);
+        snprintf(testPartition, MAXPATHLEN, "%ss%d", testPartition, index);
+        fd = qemu_open(testPartition, O_RDONLY | O_BINARY | O_LARGEFILE);
+        if (fd > 0) {
+            partitionFound = true;
+            qemu_close(fd);
+            break;
+        }
+    }
+
+    /* if a working partition on the device was not found */
+    if (partitionFound == false) {
+        printf("Error: Failed to find a working partition on disc!\n");
+        printf("If your disc is mounted on the desktop, trying unmounting it"
+               " first before using it in QEMU.\n");
+        printf("\nCommand to unmount disc: "
+                "diskutil unmountDisk %s\n", bsdPath);
+        printf("Command to mount disc: "
+               "diskutil mountDisk %s\n\n", bsdPath);
+    }
+
+    DPRINTF("Using %s as CDROM\n", testPartition);
+    strncpy(bsdPath, testPartition, MAXPATHLEN);
+}
+
+#endif /* defined(__APPLE__) && defined(__MACH__) */
 
 static int hdev_probe_device(const char *filename)
 {
@@ -2119,30 +2182,28 @@ static int hdev_open(BlockDriverState *bs, QDict *options, int flags,
 #if defined(__APPLE__) && defined(__MACH__)
     const char *filename = qdict_get_str(options, "filename");
 
-    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 = qemu_open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
-            if (fd < 0) {
-                bsdPath[strlen(bsdPath)-1] = '1';
-            } else {
-                qemu_close(fd);
+    /* If using a physical device */
+    if (strstart(filename, "/dev/", NULL)) {
+
+        /* If the physical device is a cdrom */
+        if (strcmp(filename, "/dev/cdrom") == 0) {
+            char bsdPath[MAXPATHLEN];
+            io_iterator_t mediaIterator;
+            FindEjectableCDMedia(&mediaIterator);
+            GetBSDPath(mediaIterator, bsdPath, sizeof(bsdPath), flags);
+            if (mediaIterator) {
+                IOObjectRelease(mediaIterator);
             }
+            setupCDROM(bsdPath);
             filename = bsdPath;
-            qdict_put(options, "filename", qstring_from_str(filename));
         }
 
-        if ( mediaIterator )
-            IOObjectRelease( mediaIterator );
+        /* Setup any other physical device e.g. USB flash drive */
+        else {
+            setupDevice(filename);
+        }
+
+        qdict_put(options, "filename", qstring_from_str(filename));
     }
 #endif
 
-- 
1.7.5.4


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