xl: support xend empty cdrom device syntax

xend accepts `,hdc:cdrom,r' as an empty CDROM drive.  However this is
not consistent with the existing xl syntax in
docs/misc/xl-disk-configuration.txt which requires `,,hdc:cdrom,r'
(the additional positional paramter is the format).

We fix this by spotting the case specially: when the target is empty
and the format contains a colon, reinterpret the format as
<vdev>:<devtype>.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/tools/libxl/libxlu_disk_l.l b/tools/libxl/libxlu_disk_l.l
index 7e0a63532b..f4e6b1abf3 100644
--- a/tools/libxl/libxlu_disk_l.l
+++ b/tools/libxl/libxlu_disk_l.l
@@ -217,7 +217,11 @@ phy:/.*		{ DPC->had_depr_prefix=1; DEPRECATE(0); }
         SAVESTRING("target", pdev_path, yytext);
     } else if (!DPC->had_depr_prefix &&
                DPC->disk->format == LIBXL_DISK_FORMAT_UNKNOWN) {
-        setformat(DPC,yytext);
+        if (!*DPC->disk->pdev_path && vdev_and_devtype(DPC,yytext)) {
+            DPC->disk->format = LIBXL_DISK_FORMAT_EMPTY;
+        } else {
+            setformat(DPC,yytext);
+        }
     } else if (!DPC->disk->vdev) {
         if (!vdev_and_devtype(DPC,yytext))
             SAVESTRING("vdev", vdev, yytext);