From 71bc2e8b772695c00b2ed550565724afddd6fb7e Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 29 Aug 2019 15:11:04 -0400
Subject: [PATCH 2/2] make_ext4fs: allow setting a specific UUID

The UUID was previously only reproducibly generated using a combination
of a fixed namespace and the label of the partition. This change allows
projects to specify a desired UUID instead.

Signed-off-by: Samuel Dionne-Riel <samuel@dionne-riel.com>
---
 ext4_sb.h          |  3 +++
 ext4_utils.c       | 13 ++++++++++++-
 make_ext4fs.c      |  5 +++++
 make_ext4fs_main.c |  9 +++++++--
 4 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/ext4_sb.h b/ext4_sb.h
index d6416a7..68f5cb1 100644
--- a/ext4_sb.h
+++ b/ext4_sb.h
@@ -18,6 +18,7 @@
 #define _EXT4_UTILS_EXT4_SB_H_
 
 #include "ext4_kernel_headers.h"
+#include <stdbool.h>
 
 #define EXT4_SUPER_MAGIC 0xEF53
 
@@ -42,6 +43,8 @@ struct fs_info {
 	uint32_t reserve_pcnt;
 	const char *label;
 	uint8_t no_journal;
+	bool with_uuid;
+	uint8_t uuid[16];
 };
 
 int ext4_parse_sb(struct ext4_super_block *sb, struct fs_info *info);
diff --git a/ext4_utils.c b/ext4_utils.c
index 1a886d7..e8e60fb 100644
--- a/ext4_utils.c
+++ b/ext4_utils.c
@@ -221,7 +221,13 @@ void ext4_fill_in_sb()
 	sb->s_feature_compat = info.feat_compat;
 	sb->s_feature_incompat = info.feat_incompat;
 	sb->s_feature_ro_compat = info.feat_ro_compat;
-	generate_uuid("extandroid/make_ext4fs", info.label, sb->s_uuid);
+	if (info.with_uuid) {
+		memset(sb->s_uuid, 0, sizeof(sb->s_uuid));
+		memcpy(sb->s_uuid, info.uuid, sizeof(sb->s_uuid));
+	}
+	else {
+		generate_uuid("extandroid/make_ext4fs", info.label, sb->s_uuid);
+	}
 	memset(sb->s_volume_name, 0, sizeof(sb->s_volume_name));
 	strncpy(sb->s_volume_name, info.label, sizeof(sb->s_volume_name));
 	memset(sb->s_last_mounted, 0, sizeof(sb->s_last_mounted));
@@ -521,6 +527,11 @@ int read_ext(int fd, int verbose)
 		printf("    Inodes per group: %d\n", info.inodes_per_group);
 		printf("    Inode size: %d\n", info.inode_size);
 		printf("    Label: %s\n", info.label);
+		if (info.with_uuid) {
+			char uuid[UUID_STR_LEN] = "";
+			uuid_to_string(info.uuid, uuid);
+			printf("    UUID: %s\n", uuid);
+		}
 		printf("    Blocks: %"PRIu64"\n", aux_info.len_blocks);
 		printf("    Block groups: %d\n", aux_info.groups);
 		printf("    Reserved block group size: %d\n", info.bg_desc_reserve_blocks);
diff --git a/make_ext4fs.c b/make_ext4fs.c
index 051052b..ac38d15 100644
--- a/make_ext4fs.c
+++ b/make_ext4fs.c
@@ -451,6 +451,11 @@ int make_ext4fs_internal(int fd, const char *_directory,
 	printf("    Inode size: %d\n", info.inode_size);
 	printf("    Journal blocks: %d\n", info.journal_blocks);
 	printf("    Label: %s\n", info.label);
+	if (info.with_uuid) {
+		char uuid[UUID_STR_LEN] = "";
+		uuid_to_string(info.uuid, uuid);
+		printf("    UUID: %s\n", uuid);
+	}
 
 	ext4_create_fs_aux_info();
 
diff --git a/make_ext4fs_main.c b/make_ext4fs_main.c
index 88254c3..e957a03 100644
--- a/make_ext4fs_main.c
+++ b/make_ext4fs_main.c
@@ -27,6 +27,7 @@
 
 #include "ext4_utils.h"
 #include "canned_fs_config.h"
+#include "uuid.h"
 
 extern struct fs_info info;
 
@@ -35,7 +36,7 @@ static void usage(char *path)
 {
 	fprintf(stderr, "%s [ -l <len> ] [ -j <journal size> ] [ -b <block_size> ]\n", basename(path));
 	fprintf(stderr, "    [ -g <blocks per group> ] [ -i <inodes> ] [ -I <inode size> ]\n");
-	fprintf(stderr, "    [ -m <reserved blocks percent> ] [ -L <label> ] [ -f ]\n");
+	fprintf(stderr, "    [ -m <reserved blocks percent> ] [ -L <label> ] [ -U <uuid> ] [ -f ]\n");
 	fprintf(stderr, "    [ -S file_contexts ] [ -C fs_config ] [ -T timestamp ]\n");
 	fprintf(stderr, "    [ -z | -s ] [ -w ] [ -c ] [ -J ] [ -v ] [ -B <block_list_file> ]\n");
 	fprintf(stderr, "    <filename> [<directory>]\n");
@@ -58,7 +59,7 @@ int main(int argc, char **argv)
 	time_t fixed_time = -1;
 	FILE* block_list_file = NULL;
 
-	while ((opt = getopt(argc, argv, "l:j:b:g:i:I:L:T:C:B:m:fwzJsctv")) != -1) {
+	while ((opt = getopt(argc, argv, "l:j:b:g:i:I:L:T:C:B:m:U:fwzJsctv")) != -1) {
 		switch (opt) {
 		case 'l':
 			info.len = parse_num(optarg);
@@ -81,6 +82,10 @@ int main(int argc, char **argv)
 		case 'L':
 			info.label = optarg;
 			break;
+		case 'U':
+			info.with_uuid = true;
+			parse_uuid(optarg, info.uuid);
+			break;
 		case 'f':
 			force = 1;
 			break;
-- 
2.19.2