btrfs-progs: return the fsid from make_btrfs()

The function make_btrfs() has as argument the fsid of the filesystem.
If this fsid is empty or null make_btrfs() generates a new fsid. However
If the buffer is valid (but the string is empty) the generated fsid is
copied back to the caller.

Signed-off-by: Goffredo Baroncelli <kreijack@inwind.it>
Reviewed-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

2 files changed, 10 insertions, 4 deletions

diff --git a/mkfs.c b/mkfs.c
index c069d369..962a7cd2 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -1142,7 +1142,7 @@ int main(int ac, char **av)
 	int dev_cnt = 0;
 	int saved_optind;
 	char estr[100];
-	char *fs_uuid = NULL;
+	char fs_uuid[BTRFS_UUID_UNPARSED_SIZE] = { 0 };
 	u64 features = BTRFS_MKFS_DEFAULT_FEATURES;
 
 	while(1) {
@@ -1235,7 +1235,8 @@ int main(int ac, char **av)
 				source_dir_set = 1;
 				break;
 			case 'U':
-				fs_uuid = optarg;
+				strncpy(fs_uuid, optarg,
+					BTRFS_UUID_UNPARSED_SIZE - 1);
 				break;
 			case 'K':
 				discard = 0;
@@ -1261,7 +1262,7 @@ int main(int ac, char **av)
 		exit(1);
 	}
 
-	if (fs_uuid) {
+	if (*fs_uuid) {
 		uuid_t dummy_uuid;
 
 		if (uuid_parse(fs_uuid, dummy_uuid) != 0) {
diff --git a/utils.c b/utils.c
index ef27c51e..f34c27b7 100644
--- a/utils.c
+++ b/utils.c
@@ -169,6 +169,9 @@ int test_uuid_unique(char *fs_uuid)
 	return unique;
 }
 
+/*
+ * @fs_uuid - if NULL, generates a UUID, returns back the new filesystem UUID
+ */
 int make_btrfs(int fd, const char *device, const char *label, char *fs_uuid,
 	       u64 blocks[7], u64 num_bytes, u32 nodesize,
 	       u32 sectorsize, u32 stripesize, u64 features)
@@ -201,7 +204,7 @@ int make_btrfs(int fd, const char *device, const char *label, char *fs_uuid,
 	memset(&super, 0, sizeof(super));
 
 	num_bytes = (num_bytes / sectorsize) * sectorsize;
-	if (fs_uuid) {
+	if (fs_uuid && *fs_uuid) {
 		if (uuid_parse(fs_uuid, super.fsid) != 0) {
 			fprintf(stderr, "could not parse UUID: %s\n", fs_uuid);
 			ret = -EINVAL;
@@ -214,6 +217,8 @@ int make_btrfs(int fd, const char *device, const char *label, char *fs_uuid,
 		}
 	} else {
 		uuid_generate(super.fsid);
+		if (fs_uuid)
+			uuid_unparse(super.fsid, fs_uuid);
 	}
 	uuid_generate(super.dev_item.uuid);
 	uuid_generate(chunk_tree_uuid);