[PATCH v6 30/39] builtin/verify-pack: implement an --object-format option

["brian m. carlson" <sandals@crustytoothpaste.net>]

A recently added test in t5702 started using git verify-pack outside of
a repository.  While this poses no problems with SHA-1, with SHA-256 we
implicitly rely on the setup of the repository to initialize our hash
algorithm settings.

Since we're not in a repository here, we need to provide git verify-pack
help to set things up properly.  git index-pack already knows an
--object-format option, so let's accept one as well and pass it down to
our git index-pack invocation.  Since we're now dynamically adjusting
the elements in argv, let's switch to using struct argv_array to manage
them.  Finally, let's make t5702 pass the proper argument on down to its
git verify-pack caller.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 builtin/verify-pack.c  | 23 +++++++++++++++--------
 t/t5702-protocol-v2.sh |  2 +-
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/builtin/verify-pack.c b/builtin/verify-pack.c
index c2a1a5c504..3669a90263 100644
--- a/builtin/verify-pack.c
+++ b/builtin/verify-pack.c
@@ -7,21 +7,26 @@
 #define VERIFY_PACK_VERBOSE 01
 #define VERIFY_PACK_STAT_ONLY 02
 
-static int verify_one_pack(const char *path, unsigned int flags)
+static int verify_one_pack(const char *path, unsigned int flags, const char *hash_algo)
 {
 	struct child_process index_pack = CHILD_PROCESS_INIT;
-	const char *argv[] = {"index-pack", NULL, NULL, NULL };
+	struct argv_array *argv = &index_pack.args;
 	struct strbuf arg = STRBUF_INIT;
 	int verbose = flags & VERIFY_PACK_VERBOSE;
 	int stat_only = flags & VERIFY_PACK_STAT_ONLY;
 	int err;
 
+	argv_array_push(argv, "index-pack");
+
 	if (stat_only)
-		argv[1] = "--verify-stat-only";
+		argv_array_push(argv, "--verify-stat-only");
 	else if (verbose)
-		argv[1] = "--verify-stat";
+		argv_array_push(argv, "--verify-stat");
 	else
-		argv[1] = "--verify";
+		argv_array_push(argv, "--verify");
+
+	if (hash_algo)
+		argv_array_pushf(argv, "--object-format=%s", hash_algo);
 
 	/*
 	 * In addition to "foo.pack" we accept "foo.idx" and "foo";
@@ -31,9 +36,8 @@ static int verify_one_pack(const char *path, unsigned int flags)
 	if (strbuf_strip_suffix(&arg, ".idx") ||
 	    !ends_with(arg.buf, ".pack"))
 		strbuf_addstr(&arg, ".pack");
-	argv[2] = arg.buf;
+	argv_array_push(argv, arg.buf);
 
-	index_pack.argv = argv;
 	index_pack.git_cmd = 1;
 
 	err = run_command(&index_pack);
@@ -60,12 +64,15 @@ int cmd_verify_pack(int argc, const char **argv, const char *prefix)
 {
 	int err = 0;
 	unsigned int flags = 0;
+	const char *object_format = NULL;
 	int i;
 	const struct option verify_pack_options[] = {
 		OPT_BIT('v', "verbose", &flags, N_("verbose"),
 			VERIFY_PACK_VERBOSE),
 		OPT_BIT('s', "stat-only", &flags, N_("show statistics only"),
 			VERIFY_PACK_STAT_ONLY),
+		OPT_STRING(0, "object-format", &object_format, N_("hash"),
+			   N_("specify the hash algorithm to use")),
 		OPT_END()
 	};
 
@@ -75,7 +82,7 @@ int cmd_verify_pack(int argc, const char **argv, const char *prefix)
 	if (argc < 1)
 		usage_with_options(verify_pack_usage, verify_pack_options);
 	for (i = 0; i < argc; i++) {
-		if (verify_one_pack(argv[i], flags))
+		if (verify_one_pack(argv[i], flags, object_format))
 			err = 1;
 	}
 
diff --git a/t/t5702-protocol-v2.sh b/t/t5702-protocol-v2.sh
index 1b54c35b01..7fc22171e7 100755
--- a/t/t5702-protocol-v2.sh
+++ b/t/t5702-protocol-v2.sh
@@ -829,7 +829,7 @@ test_expect_success 'part of packfile response provided as URI' '
 	# Ensure that my-blob and other-blob are in separate packfiles.
 	for idx in http_child/.git/objects/pack/*.idx
 	do
-		git verify-pack --verbose $idx >out &&
+		git verify-pack --object-format=$(test_oid algo) --verbose $idx >out &&
 		{
 			grep "^[0-9a-f]\{16,\} " out || :
 		} >out.objectlist &&