git: 95ac5b0e27e9 - main - mkimg: Add a reproducible mode

The branch main has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=95ac5b0e27e9070ba91c28f9a6ecbed743d148cb

commit 95ac5b0e27e9070ba91c28f9a6ecbed743d148cb
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2025-06-26 14:28:14 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2025-06-26 14:44:01 +0000

    mkimg: Add a reproducible mode
    
    mkimg embeds a UUID in the GPT header and uses the current time of day
    to generate it, so its output is not reproducible by default.  Add a -R
    flag to ask it to use a fixed time for UUID generation.
    
    Merge the FreeBSD-specific implementation of osdep_uuidgen() with that
    of Linux, as the use of uuidgen(2) is incompatible with reproducible
    output mode.
    
    Reviewed by:    bnovkov
    MFC after:      2 weeks
    Sponsored by:   The FreeBSD Foundation
    Sponsored by:   Klara, Inc.
    Differential Revision:  https://reviews.freebsd.org/D49716
---
 usr.bin/mkimg/mkimg.1 |  8 +++++++-
 usr.bin/mkimg/mkimg.c | 10 +++++++++-
 usr.bin/mkimg/mkimg.h |  3 +++
 usr.bin/mkimg/uuid.c  | 19 +++++--------------
 4 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/usr.bin/mkimg/mkimg.1 b/usr.bin/mkimg/mkimg.1
index 82bbee53a267..f6b151d2d5c7 100644
--- a/usr.bin/mkimg/mkimg.1
+++ b/usr.bin/mkimg/mkimg.1
@@ -22,7 +22,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd March 12, 2024
+.Dd June 25, 2025
 .Dt MKIMG 1
 .Os
 .Sh NAME
@@ -41,6 +41,7 @@
 .Op Fl f Ar format
 .Op Fl o Ar outfile
 .Op Fl a Ar active
+.Op Fl R
 .Op Fl v
 .Op Fl y
 .Op Fl s Ar scheme Op Fl p Ar partition ...
@@ -138,6 +139,11 @@ option is a shorthand to specify the minimum and maximum capacity at the
 same time.
 .Pp
 The
+.Fl R
+option enables reproducible mode: any timestamps or random identifiers will
+be fixed so as to ensure consistent output.
+.Pp
+The
 .Fl v
 option increases the level of output that the
 .Nm
diff --git a/usr.bin/mkimg/mkimg.c b/usr.bin/mkimg/mkimg.c
index 3cd9b03c06e9..c8872ebb1bc6 100644
--- a/usr.bin/mkimg/mkimg.c
+++ b/usr.bin/mkimg/mkimg.c
@@ -61,6 +61,8 @@ static struct option longopts[] = {
 static uint64_t min_capacity = 0;
 static uint64_t max_capacity = 0;
 
+bool reproducible = false;
+
 struct partlisthead partlist = TAILQ_HEAD_INITIALIZER(partlist);
 u_int nparts = 0;
 
@@ -561,7 +563,7 @@ main(int argc, char *argv[])
 
 	bcfd = -1;
 	outfd = 1;	/* Write to stdout by default */
-	while ((c = getopt_long(argc, argv, "a:b:c:C:f:o:p:s:vyH:P:S:T:",
+	while ((c = getopt_long(argc, argv, "a:b:c:C:f:o:p:s:vyH:P:RS:T:",
 	    longopts, NULL)) != -1) {
 		switch (c) {
 		case 'a':	/* ACTIVE PARTITION, if supported */
@@ -606,6 +608,9 @@ main(int argc, char *argv[])
 			if (error)
 				errc(EX_DATAERR, error, "partition");
 			break;
+		case 'R':
+			reproducible = true;
+			break;
 		case 's':	/* SCHEME */
 			if (scheme_selected() != NULL)
 				usage("multiple schemes given");
@@ -675,6 +680,9 @@ main(int argc, char *argv[])
 	if (max_capacity != 0 && min_capacity > max_capacity)
 		usage("minimum capacity cannot be larger than the maximum one");
 
+	if (reproducible)
+		srandom(42);
+
 	if (secsz > blksz) {
 		if (blksz != 0)
 			errx(EX_DATAERR, "the physical block size cannot "
diff --git a/usr.bin/mkimg/mkimg.h b/usr.bin/mkimg/mkimg.h
index e85f77de0ec7..608de458e83c 100644
--- a/usr.bin/mkimg/mkimg.h
+++ b/usr.bin/mkimg/mkimg.h
@@ -29,6 +29,9 @@
 
 #include <sys/queue.h>
 #include <sys/types.h>
+#include <stdbool.h>
+
+extern bool reproducible;	/* Generate reproducible output. */
 
 struct part {
 	TAILQ_ENTRY(part) link;
diff --git a/usr.bin/mkimg/uuid.c b/usr.bin/mkimg/uuid.c
index 470d92c76293..f3415a8c1111 100644
--- a/usr.bin/mkimg/uuid.c
+++ b/usr.bin/mkimg/uuid.c
@@ -45,20 +45,9 @@ osdep_uuidgen(mkimg_uuid_t *uuid)
 }
 #endif	/* __APPLE__ */
 
-#ifdef __FreeBSD__
-#include <sys/uuid.h>
-
-static void
-osdep_uuidgen(mkimg_uuid_t *uuid)
-{
-
-	uuidgen((void *)uuid, 1);
-}
-#endif	/* __FreeBSD__ */
-
-#ifdef __linux__
+#if defined(__linux__) || defined(__FreeBSD__)
+#include <sys/time.h>
 #include <stdlib.h>
-#include <time.h>
 
 static void
 osdep_uuidgen(mkimg_uuid_t *uuid)
@@ -68,7 +57,9 @@ osdep_uuidgen(mkimg_uuid_t *uuid)
 	u_int i;
 	uint16_t seq;
 
-	if (gettimeofday(&tv, NULL) == -1)
+	if (reproducible)
+		memset(&tv, 0, sizeof(tv));
+	else if (gettimeofday(&tv, NULL) == -1)
 		abort();
 
 	time += (uint64_t)tv.tv_sec * 10000000LL;