gpt: support random UUIDs without setting environment variables

Currently, an environment variable must be used to store the randomly
generated UUID for each partition. This is not necessary, so make storing
the UUID optional. Now passing uuid_disk and uuid are optional when random
UUIDs are enabled.

Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Przemyslaw Marczak <p.marczak@samsung.com>

common/cmd_gpt.c

@@ -154,17 +154,24 @@ static int set_gpt_info(block_dev_desc_t *dev_desc,
 
 	/* extract disk guid */
 	s = str;
-	tok = strsep(&s, ";");
-	val = extract_val(tok, "uuid_disk");
+	val = extract_val(str, "uuid_disk");
 	if (!val) {
+#ifdef CONFIG_RANDOM_UUID
+		*str_disk_guid = malloc(UUID_STR_LEN + 1);
+		gen_rand_uuid_str(*str_disk_guid, UUID_STR_FORMAT_STD);
+#else
 		free(str);
 		return -2;
+#endif
+	} else {
+		val = strsep(&val, ";");
+		if (extract_env(val, &p))
+			p = val;
+		*str_disk_guid = strdup(p);
+		free(val);
+		/* Move s to first partition */
+		strsep(&s, ";");
 	}
-	if (extract_env(val, &p))
-		p = val;
-	*str_disk_guid = strdup(p);
-	free(val);
-
 	if (strlen(s) == 0)
 		return -3;
 
@@ -192,20 +199,25 @@ static int set_gpt_info(block_dev_desc_t *dev_desc,
 
 		/* uuid */
 		val = extract_val(tok, "uuid");
-		if (!val) { /* 'uuid' is mandatory */
-			errno = -4;
-			goto err;
-		}
-		if (extract_env(val, &p))
-			p = val;
-		if (strlen(p) >= sizeof(parts[i].uuid)) {
-			printf("Wrong uuid format for partition %d\n", i);
+		if (!val) {
+			/* 'uuid' is optional if random uuid's are enabled */
+#ifdef CONFIG_RANDOM_UUID
+			gen_rand_uuid_str(parts[i].uuid, UUID_STR_FORMAT_STD);
+#else
 			errno = -4;
 			goto err;
+#endif
+		} else {
+			if (extract_env(val, &p))
+				p = val;
+			if (strlen(p) >= sizeof(parts[i].uuid)) {
+				printf("Wrong uuid format for partition %d\n", i);
+				errno = -4;
+				goto err;
+			}
+			strcpy((char *)parts[i].uuid, p);
+			free(val);
 		}
-		strcpy((char *)parts[i].uuid, p);
-		free(val);
-
 		/* name */
 		val = extract_val(tok, "name");
 		if (!val) { /* name is mandatory */

doc/README.gpt

@@ -157,11 +157,13 @@ To restore GUID partition table one needs to:
      "partitions=uuid_disk=${uuid_gpt_disk};name=${uboot_name},
 	size=${uboot_size},uuid=${uboot_uuid};"
 
-   Fields 'name', 'size' and 'uuid' are mandatory for every partition.
+   The fields 'name' and 'size' are mandatory for every partition.
    The field 'start' is optional.
 
-   option: CONFIG_RANDOM_UUID
-   If any partition "UUID" no exists then it is randomly generated.
+   The fields 'uuid' and 'uuid_disk' are optional if CONFIG_RANDOM_UUID is
+   enabled. A random uuid will be used if omitted or they point to an empty/
+   non-existent environment variable. The environment variable will be set to
+   the generated UUID.
 
 2. Define 'CONFIG_EFI_PARTITION' and 'CONFIG_CMD_GPT'