linux: only return the description of a key

keyctl_describe returns a string of format:

  %s;%d;%d;%08x;%s

where the arguments are: key type name, key UID, key GID, key
permissions mask and key description. The key description will not
contain any semicolons.

The last entry contains the description which is what
nvme_describe_key_serial promisses to return.

Signed-off-by: Daniel Wagner <[email protected]>

Author: dwsuse

src/nvme/linux.c

@@ -1203,11 +1203,21 @@ long nvme_lookup_keyring(const char *keyring)
 
 char *nvme_describe_key_serial(long key_id)
 {
-	char *desc;
+	_cleanup_free_ char *str = NULL;
+	char *last;
 
-	if (keyctl_describe_alloc(key_id, &desc) < 0)
-		desc = NULL;
-	return desc;
+	if (keyctl_describe_alloc(key_id, &str) < 0)
+		return NULL;
+
+	last = strrchr(str, ';');
+	if (!last)
+		return NULL;
+
+	last++;
+	if (strlen(last) == 0)
+		return NULL;
+
+	return strdup(last);
 }
 
 long nvme_lookup_key(const char *type, const char *identity)