[PATCH 4/4] mkfs: add option to use a pre-defined UUID

[Gao Xiang]

Usage: mkfs.erofs -U<uuid> <imagefile> <srcdir>

The filesystem UUID can now be optionally specified during filesystem
creation. The default behavior is still to generate a random UUID.

This is useful for reproducible builds.

Signed-off-by: Gao Xiang <hsiangkao at redhat.com>
---
 man/mkfs.erofs.1 |  6 ++++++
 mkfs/main.c      | 13 ++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/man/mkfs.erofs.1 b/man/mkfs.erofs.1
index 891c5a8..dcaf9d7 100644
--- a/man/mkfs.erofs.1
+++ b/man/mkfs.erofs.1
@@ -52,6 +52,12 @@ Forcely generate extended inodes (64-byte inodes) to output.
 Set all files to the given UNIX timestamp. Reproducible builds requires setting
 all to a specific one.
 .TP
+.BI "\-U " UUID
+Set the universally unique identifier (UUID) of the filesystem to
+.IR UUID .
+The format of the UUID is a series of hex digits separated by hyphens,
+like this: "c1b9d5a2-f162-11cf-9ece-0020afc76f16".
+.TP
 .BI "\-\-exclude-path=" path
 Ignore file that matches the exact literal path.
 You may give multiple `--exclude-path' options.
diff --git a/mkfs/main.c b/mkfs/main.c
index 0e17314..c63b274 100644
--- a/mkfs/main.c
+++ b/mkfs/main.c
@@ -66,6 +66,9 @@ static void usage(void)
 	      " -x#                set xattr tolerance to # (< 0, disable xattrs; default 2)\n"
 	      " -EX[,...]          X=extended options\n"
 	      " -T#                set a fixed UNIX timestamp # to all files\n"
+#ifdef HAVE_LIBUUID
+	      " -UX                use a given filesystem UUID\n"
+#endif
 	      " --exclude-path=X   avoid including file X (X = exact literal path)\n"
 	      " --exclude-regex=X  avoid including files that match X (X = regular expression)\n"
 #ifdef HAVE_LIBSELINUX
@@ -149,7 +152,7 @@ static int mkfs_parse_options_cfg(int argc, char *argv[])
 	char *endptr;
 	int opt, i;
 
-	while((opt = getopt_long(argc, argv, "d:x:z:E:T:",
+	while((opt = getopt_long(argc, argv, "d:x:z:E:T:U:",
 				 long_options, NULL)) != -1) {
 		switch (opt) {
 		case 'z':
@@ -200,6 +203,14 @@ static int mkfs_parse_options_cfg(int argc, char *argv[])
 			}
 			cfg.c_timeinherit = TIMESTAMP_FIXED;
 			break;
+#ifdef HAVE_LIBUUID
+		case 'U':
+			if (uuid_parse(optarg, sbi.uuid)) {
+				erofs_err("invalid UUID %s", optarg);
+				return -EINVAL;
+			}
+			break;
+#endif
 		case 2:
 			opt = erofs_parse_exclude_path(optarg, false);
 			if (opt) {
-- 
2.18.1