From 0e479ac8f7a2d846f5e73fb07d7504fedb89d653 Mon Sep 17 00:00:00 2001
From: Tim Kientzle <kientzle@FreeBSD.org>
Date: Sat, 9 Oct 2010 05:31:08 +0000
Subject: [PATCH] Add -D (deterministic) option to ar. When set, it forces all
 timestamps and owners to zero and modes to 0644.  Useful for producing
 libraries that are bitwise identical across multiple build runs.

Submitted by:	Erik Cederstrand
Reviewed by:	Kai Wang
---
 usr.bin/ar/ar.1    | 11 +++++++++++
 usr.bin/ar/ar.c    | 13 +++++++++----
 usr.bin/ar/ar.h    |  1 +
 usr.bin/ar/write.c | 24 +++++++++++++++++++-----
 4 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/usr.bin/ar/ar.1 b/usr.bin/ar/ar.1
index 3a8b75373aab..c64c7f64ac6e 100644
--- a/usr.bin/ar/ar.1
+++ b/usr.bin/ar/ar.1
@@ -62,6 +62,7 @@
 .Op Fl a Ar position-after
 .Op Fl b Ar position-before
 .Op Fl c
+.Op Fl D
 .Op Fl i Ar position-before
 .Op Fl j
 .Op Fl s
@@ -179,6 +180,16 @@ from the archive specified by argument
 .Ar archive .
 The archive's symbol table, if present, is updated to reflect
 the new contents of the archive.
+.It Fl D
+When used in combination with the 
+.Fl r
+or
+.Fl q
+option, insert 0's instead of the real mtime, uid and gid values 
+and 0644 instead of file mode from the members named by arguments
+.Ar files ... .
+This ensures that checksums on the resulting archives are reproducible
+when member contents are identical.
 .It Fl f
 Synonymous with option
 .Fl T .
diff --git a/usr.bin/ar/ar.c b/usr.bin/ar/ar.c
index 1fe92fbef3d8..e5bc1d2682aa 100644
--- a/usr.bin/ar/ar.c
+++ b/usr.bin/ar/ar.c
@@ -154,7 +154,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((opt = getopt_long(argc, argv, "abCcdfijlMmopqrSsTtuVvxz",
+	while ((opt = getopt_long(argc, argv, "abCcdDfijlMmopqrSsTtuVvxz",
 	    longopts, NULL)) != -1) {
 		switch(opt) {
 		case 'a':
@@ -173,6 +173,9 @@ main(int argc, char **argv)
 		case 'd':
 			set_mode(bsdar, opt);
 			break;
+		case 'D':
+			bsdar->options |= AR_D;
+			break;
 		case 'f':
 		case 'T':
 			bsdar->options |= AR_TR;
@@ -269,6 +272,8 @@ main(int argc, char **argv)
 		only_mode(bsdar, "-c", "qr");
 	if (bsdar->options & AR_CC)
 		only_mode(bsdar, "-C", "x");
+	if (bsdar->options & AR_D)
+		only_mode(bsdar, "-D", "qr");
 	if (bsdar->options & AR_O)
 		only_mode(bsdar, "-o", "x");
 	if (bsdar->options & AR_SS)
@@ -356,9 +361,9 @@ bsdar_usage(void)
 	(void)fprintf(stderr, "\tar -m [-Tjsvz] archive file ...\n");
 	(void)fprintf(stderr, "\tar -m [-Tabijsvz] position archive file ...\n");
 	(void)fprintf(stderr, "\tar -p [-Tv] archive [file ...]\n");
-	(void)fprintf(stderr, "\tar -q [-Tcjsvz] archive file ...\n");
-	(void)fprintf(stderr, "\tar -r [-Tcjsuvz] archive file ...\n");
-	(void)fprintf(stderr, "\tar -r [-Tabcijsuvz] position archive file ...\n");
+	(void)fprintf(stderr, "\tar -q [-TcDjsvz] archive file ...\n");
+	(void)fprintf(stderr, "\tar -r [-TcDjsuvz] archive file ...\n");
+	(void)fprintf(stderr, "\tar -r [-TabcDijsuvz] position archive file ...\n");
 	(void)fprintf(stderr, "\tar -s [-jz] archive\n");
 	(void)fprintf(stderr, "\tar -t [-Tv] archive [file ...]\n");
 	(void)fprintf(stderr, "\tar -x [-CTouv] archive [file ...]\n");
diff --git a/usr.bin/ar/ar.h b/usr.bin/ar/ar.h
index 60fe8e8ef01f..77dd49219eab 100644
--- a/usr.bin/ar/ar.h
+++ b/usr.bin/ar/ar.h
@@ -43,6 +43,7 @@
 #define AR_U	0x0200		/* only extract or update newer members.*/
 #define AR_V	0x0400		/* verbose mode */
 #define AR_Z	0x0800		/* gzip compression */
+#define AR_D	0x1000		/* insert dummy mode, mtime, uid and gid */
 
 #define DEF_BLKSZ 10240		/* default block size */
 
diff --git a/usr.bin/ar/write.c b/usr.bin/ar/write.c
index 8b6fbdf5a2c5..d27a767049f8 100644
--- a/usr.bin/ar/write.c
+++ b/usr.bin/ar/write.c
@@ -163,11 +163,24 @@ create_obj_from_file(struct bsdar *bsdar, const char *name, time_t mtime)
 	if (mtime != 0 && bsdar->options & AR_U && sb.st_mtime <= mtime)
 		goto giveup;
 
-	obj->uid = sb.st_uid;
-	obj->gid = sb.st_gid;
-	obj->md = sb.st_mode;
+	/*
+	 * When option '-D' is specified, mtime and UID / GID from the file
+	 * will be replaced with 0, and file mode with 644. This ensures that 
+	 * checksums will match for two archives containing the exact same
+	 * files.
+	 */
+	if (bsdar->options & AR_D) {
+		obj->uid = 0;
+		obj->gid = 0;
+		obj->mtime = 0;
+		obj->md = S_IFREG | 0644;
+	} else {
+		obj->uid = sb.st_uid;
+		obj->gid = sb.st_gid;
+		obj->mtime = sb.st_mtime;
+		obj->md = sb.st_mode;
+	}
 	obj->size = sb.st_size;
-	obj->mtime = sb.st_mtime;
 	obj->dev = sb.st_dev;
 	obj->ino = sb.st_ino;
 
@@ -621,7 +634,8 @@ write_objs(struct bsdar *bsdar)
 	    bsdar->options & AR_S) {
 		entry = archive_entry_new();
 		archive_entry_copy_pathname(entry, "/");
-		archive_entry_set_mtime(entry, time(NULL), 0);
+		if ((bsdar->options & AR_D) == 0)
+			archive_entry_set_mtime(entry, time(NULL), 0);
 		archive_entry_set_size(entry, (bsdar->s_cnt + 1) *
 		    sizeof(uint32_t) + bsdar->s_sn_sz);
 		AC(archive_write_header(a, entry));