hmp: Add read-only-mode option to change command

Expose the new read-only-mode option of 'blockdev-change-medium' for the
'change' HMP command.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 8939b98..f3de407 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -194,8 +194,8 @@
 
     {
         .name       = "change",
-        .args_type  = "device:B,target:F,arg:s?",
-        .params     = "device filename [format]",
+        .args_type  = "device:B,target:F,arg:s?,read-only-mode:s?",
+        .params     = "device filename [format [read-only-mode]]",
         .help       = "change a removable medium, optional format",
         .mhandler.cmd = hmp_change,
     },
@@ -206,7 +206,7 @@
 Change the configuration of a device.
 
 @table @option
-@item change @var{diskdevice} @var{filename} [@var{format}]
+@item change @var{diskdevice} @var{filename} [@var{format} [@var{read-only-mode}]]
 Change the medium for a removable disk device to point to @var{filename}. eg
 
 @example
@@ -215,6 +215,20 @@
 
 @var{format} is optional.
 
+@var{read-only-mode} may be used to change the read-only status of the device.
+It accepts the following values:
+
+@table @var
+@item retain
+Retains the current status; this is the default.
+
+@item read-only
+Makes the device read-only.
+
+@item read-write
+Makes the device writable.
+@end table
+
 @item change vnc @var{display},@var{options}
 Change the configuration of the VNC server. The valid syntax for @var{display}
 and @var{options} are described at @ref{sec_invocation}. eg