Merge branch 'rs/archive-mtime'

"git archive HEAD^{tree}" records the paths with the current
timestamp in the archive, making it harder to obtain a stable
output.  The command learned the --mtime option to specify an
arbitrary timestamp (e.g. --mtime="@0 +0000" for the epoch).

* rs/archive-mtime:
  archive: add --mtime

Documentation/git-archive.txt

@@ -86,6 +86,11 @@ cases, write an untracked file and use `--add-file` instead.
 	Look for attributes in .gitattributes files in the working tree
 	as well (see <<ATTRIBUTES>>).
 
+--mtime=<time>::
+	Set modification time of archive entries.  Without this option
+	the committer time is used if `<tree-ish>` is a commit or tag,
+	and the current time if it is a tree.
+
 <extra>::
 	This can be any options that the archiver backend understands.
 	See next section.

archive.c

@@ -472,6 +472,8 @@ static void parse_treeish_arg(const char **argv,
 		commit_oid = NULL;
 		archive_time = time(NULL);
 	}
+	if (ar_args->mtime_option)
+		archive_time = approxidate(ar_args->mtime_option);
 
 	tree = parse_tree_indirect(&oid);
 	if (!tree)
@@ -586,6 +588,7 @@ static int parse_archive_args(int argc, const char **argv,
 	const char *remote = NULL;
 	const char *exec = NULL;
 	const char *output = NULL;
+	const char *mtime_option = NULL;
 	int compression_level = -1;
 	int verbose = 0;
 	int i;
@@ -607,6 +610,9 @@ static int parse_archive_args(int argc, const char **argv,
 		OPT_BOOL(0, "worktree-attributes", &worktree_attributes,
 			N_("read .gitattributes in working directory")),
 		OPT__VERBOSE(&verbose, N_("report archived files on stderr")),
+		{ OPTION_STRING, 0, "mtime", &mtime_option, N_("time"),
+		  N_("set modification time of archive entries"),
+		  PARSE_OPT_NONEG },
 		OPT_NUMBER_CALLBACK(&compression_level,
 			N_("set compression level"), number_callback),
 		OPT_GROUP(""),
@@ -668,6 +674,7 @@ static int parse_archive_args(int argc, const char **argv,
 	args->base = base;
 	args->baselen = strlen(base);
 	args->worktree_attributes = worktree_attributes;
+	args->mtime_option = mtime_option;
 
 	return argc;
 }

archive.h

@@ -16,6 +16,7 @@ struct archiver_args {
 	struct tree *tree;
 	const struct object_id *commit_oid;
 	const struct commit *commit;
+	const char *mtime_option;
 	timestamp_t time;
 	struct pathspec pathspec;
 	unsigned int verbose : 1;

t/t5000-tar-tree.sh

@@ -105,6 +105,18 @@ check_added() {
 	'
 }
 
+check_mtime() {
+	dir=$1
+	path_in_archive=$2
+	mtime=$3
+
+	test_expect_success " validate mtime of $path_in_archive" '
+		test-tool chmtime --get $dir/$path_in_archive >actual.mtime &&
+		echo $mtime >expect.mtime &&
+		test_cmp expect.mtime actual.mtime
+	'
+}
+
 test_expect_success 'setup' '
 	test_oid_cache <<-EOF
 	obj sha1:19f9c8273ec45a8938e6999cb59b3ff66739902a
@@ -174,6 +186,13 @@ test_expect_success 'git archive' '
 
 check_tar b
 
+test_expect_success 'git archive --mtime' '
+	git archive --mtime=2002-02-02T02:02:02-0200 HEAD >with_mtime.tar
+'
+
+check_tar with_mtime
+check_mtime with_mtime a/a 1012622522
+
 test_expect_success 'git archive --prefix=prefix/' '
 	git archive --prefix=prefix/ HEAD >with_prefix.tar
 '