[dm-devel] [PATCH v2 04/12] kpartx: relax and improve UUID check in dm_compare_uuid

[Martin Wilck]

It is wrong to assume that UUIDs of parent devices always contain
"mpath". Fix that, and make the check for the kpartx-specific prefix
"part%d-" stricter and more explicit.

Moreover, avoid duplication of string constants and properly express
the dependencies of the various constants.

Signed-off-by: Martin Wilck <mwilck at suse.com>
---
 kpartx/devmapper.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/kpartx/devmapper.c b/kpartx/devmapper.c
index 8aca9592..8b125be5 100644
--- a/kpartx/devmapper.c
+++ b/kpartx/devmapper.c
@@ -10,8 +10,10 @@
 #include <errno.h>
 #include "devmapper.h"
 
-#define UUID_PREFIX "part%d-"
-#define MAX_PREFIX_LEN 8
+#define _UUID_PREFIX "part"
+#define UUID_PREFIX _UUID_PREFIX "%d-"
+#define _UUID_PREFIX_LEN (sizeof(_UUID_PREFIX) - 1)
+#define MAX_PREFIX_LEN (_UUID_PREFIX_LEN + 4)
 #define PARAMS_SIZE 1024
 
 int dm_prereq(char * str, int x, int y, int z)
@@ -417,9 +419,13 @@ dm_compare_uuid(const char *mapuuid, const char *partname)
 	if (!partuuid)
 		return 1;
 
-	if (!strncmp(partuuid, "part", 4)) {
-		char *p = strstr(partuuid, "mpath-");
-		if (p && !strcmp(mapuuid, p))
+	if (!strncmp(partuuid, _UUID_PREFIX, _UUID_PREFIX_LEN)) {
+		char *p = partuuid + _UUID_PREFIX_LEN;
+		/* skip partition number */
+		while (isdigit(*p))
+			p++;
+		if (p != partuuid + _UUID_PREFIX_LEN && *p == '-' &&
+		    !strcmp(mapuuid, p + 1))
 			r = 0;
 	}
 	free(partuuid);
-- 
2.12.2