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>

5 files changed, 28 insertions, 8 deletions

diff --git a/docs/misc/xl-disk-configuration.txt b/docs/misc/xl-disk-configuration.txt
index 740b8f6429..5da5e11ea4 100644
--- a/docs/misc/xl-disk-configuration.txt
+++ b/docs/misc/xl-disk-configuration.txt
@@ -221,3 +221,14 @@ to specify several of these, for example:
   "tap:aio:/some/path..."
 
 All of these prefixes are now stripped and ignored.
+
+
+Missing format and empty target
+-------------------------------
+
+The following syntax is also supported:
+
+  ,<vdev>:<devtype>,<access>   (deprecated)
+
+This is soley for compatibility with xend's syntax for empty cdroms,
+which is (for example) ",hdc:cdrom,r".
diff --git a/tools/libxl/check-xl-disk-parse b/tools/libxl/check-xl-disk-parse
index 7a337802d5..ffe3613bde 100755
--- a/tools/libxl/check-xl-disk-parse
+++ b/tools/libxl/check-xl-disk-parse
@@ -123,6 +123,7 @@ disk: {
 EOF
 one 0 devtype=cdrom,,,hdc
 one 0 ,,hdc:cdrom,r
+one 0 ,hdc:cdrom,r
 one 0 vdev=hdc,access=r,devtype=cdrom,target=
 one 0 ,empty,hdc:cdrom,r
 
diff --git a/tools/libxl/libxlu_disk_l.c b/tools/libxl/libxlu_disk_l.c
index b4ad65108a..f6903853ee 100644
--- a/tools/libxl/libxlu_disk_l.c
+++ b/tools/libxl/libxlu_disk_l.c
@@ -1404,7 +1404,11 @@ YY_RULE_SETUP
         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);
@@ -1419,7 +1423,7 @@ YY_RULE_SETUP
 	YY_BREAK
 case 23:
 YY_RULE_SETUP
-#line 233 "libxlu_disk_l.l"
+#line 237 "libxlu_disk_l.l"
 {
     BEGIN(LEXERR);
     yymore();
@@ -1427,17 +1431,17 @@ YY_RULE_SETUP
 	YY_BREAK
 case 24:
 YY_RULE_SETUP
-#line 237 "libxlu_disk_l.l"
+#line 241 "libxlu_disk_l.l"
 {
     xlu__disk_err(DPC,yytext,"bad disk syntax"); return 0;
 }
 	YY_BREAK
 case 25:
 YY_RULE_SETUP
-#line 240 "libxlu_disk_l.l"
+#line 244 "libxlu_disk_l.l"
 YY_FATAL_ERROR( "flex scanner jammed" );
 	YY_BREAK
-#line 1441 "libxlu_disk_l.c"
+#line 1445 "libxlu_disk_l.c"
 			case YY_STATE_EOF(INITIAL):
 			case YY_STATE_EOF(LEXERR):
 				yyterminate();
@@ -2529,4 +2533,4 @@ void xlu__disk_yyfree (void * ptr , yyscan_t yyscanner)
 
 #define YYTABLES_NAME "yytables"
 
-#line 240 "libxlu_disk_l.l"
+#line 244 "libxlu_disk_l.l"
diff --git a/tools/libxl/libxlu_disk_l.h b/tools/libxl/libxlu_disk_l.h
index 4d0328e4f5..26c9a860d4 100644
--- a/tools/libxl/libxlu_disk_l.h
+++ b/tools/libxl/libxlu_disk_l.h
@@ -340,7 +340,7 @@ extern int xlu__disk_yylex (yyscan_t yyscanner);
 #undef YY_DECL
 #endif
 
-#line 240 "libxlu_disk_l.l"
+#line 244 "libxlu_disk_l.l"
 
 #line 346 "libxlu_disk_l.h"
 #undef xlu__disk_yyIN_HEADER
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);