qemu: pass the information when disks are read-only

* src/qemu/qemu_conf.c: add the ",readonly=on" for read-only disks
  and also parse it back in qemuParseCommandLineDisk()
* tests/qemuxml2argvtest.c
  tests/qemuxml2argvdata/qemuxml2argv-disk-drive-readonly-disk.args
  tests/qemuxml2argvdata/qemuxml2argv-disk-drive-readonly-disk.xml:
  add a specific regression test

src/qemu/qemu_conf.c

@@ -2398,6 +2398,9 @@ qemuBuildDriveStr(virDomainDiskDefPtr disk,
     if (bootable &&
         disk->device == VIR_DOMAIN_DISK_DEVICE_DISK)
         virBufferAddLit(&opt, ",boot=on");
+    if (disk->readonly &&
+        qemuCmdFlags & QEMUD_CMD_FLAG_DEVICE)
+        virBufferAddLit(&opt, ",readonly=on");
     if (disk->driverType &&
         disk->type != VIR_DOMAIN_DISK_TYPE_DIR &&
         qemuCmdFlags & QEMUD_CMD_FLAG_DRIVE_FORMAT)
@@ -4694,6 +4697,9 @@ qemuParseCommandLineDisk(const char *val,
                                 _("cannot parse drive unit '%s'"), val);
                 goto cleanup;
             }
+        } else if (STREQ(keywords[i], "readonly")) {
+            if ((values[i] == NULL) || STREQ(values[i], "on"))
+                def->readonly = 1;
         }
     }
 

tests/qemuxml2argvdata/qemuxml2argv-disk-drive-readonly-disk.args

+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu -S -M pc -m 214 -smp 1 -nographic -nodefaults -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -drive file=/dev/HostVG/QEMUGuest1,if=none,id=drive-ide0-0-0 -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 -drive file=/dev/sr0,if=none,media=cdrom,id=drive-ide0-1-0,readonly=on -device ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -usb -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3

tests/qemuxml2argvdata/qemuxml2argv-disk-drive-readonly-disk.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory>219200</memory>
+  <currentMemory>219200</currentMemory>
+  <vcpu>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <address type='drive' controller='0' bus='0' unit='0'/>
+    </disk>
+    <disk type='block' device='cdrom'>
+       <source dev='/dev/sr0'/>
+       <target dev='hdc' bus='ide'/>
+       <readonly/>
+       <address type='drive' controller='0' bus='1' unit='0'/>
+    </disk>
+    <controller type='ide' index='0'/>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -249,6 +249,8 @@ mymain(int argc, char **argv)
             QEMUD_CMD_FLAG_DRIVE_BOOT | QEMUD_CMD_FLAG_DRIVE_FORMAT);
     DO_TEST("disk-drive-fat", QEMUD_CMD_FLAG_DRIVE |
             QEMUD_CMD_FLAG_DRIVE_BOOT | QEMUD_CMD_FLAG_DRIVE_FORMAT);
+    DO_TEST("disk-drive-readonly-disk", QEMUD_CMD_FLAG_DRIVE |
+            QEMUD_CMD_FLAG_DEVICE);
     DO_TEST("disk-drive-fmt-qcow", QEMUD_CMD_FLAG_DRIVE |
             QEMUD_CMD_FLAG_DRIVE_BOOT | QEMUD_CMD_FLAG_DRIVE_FORMAT);
     DO_TEST("disk-drive-shared", QEMUD_CMD_FLAG_DRIVE |