index-pack: support checking objects but not links

The index-pack command currently supports the
--check-self-contained-and-connected argument, for internal use only,
that instructs it to only check for broken links and not broken objects.
For partial clones, we need the inverse, so add a --fsck-objects
argument that checks for broken objects and not broken links, also for
internal use only.

This will be used by fetch-pack in a subsequent patch.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-index-pack.txt

@@ -77,6 +77,9 @@ OPTIONS
 --check-self-contained-and-connected::
 	Die if the pack contains broken links. For internal use only.
 
+--fsck-objects::
+	Die if the pack contains broken objects. For internal use only.
+
 --threads=<n>::
 	Specifies the number of threads to spawn when resolving
 	deltas. This requires that index-pack be compiled with

builtin/index-pack.c

@@ -828,7 +828,7 @@ static void sha1_object(const void *data, struct object_entry *obj_entry,
 		free(has_data);
 	}
 
-	if (strict) {
+	if (strict || do_fsck_object) {
 		read_lock();
 		if (type == OBJ_BLOB) {
 			struct blob *blob = lookup_blob(oid);
@@ -854,7 +854,7 @@ static void sha1_object(const void *data, struct object_entry *obj_entry,
 			if (do_fsck_object &&
 			    fsck_object(obj, buf, size, &fsck_options))
 				die(_("Error in object"));
-			if (fsck_walk(obj, NULL, &fsck_options))
+			if (strict && fsck_walk(obj, NULL, &fsck_options))
 				die(_("Not all child objects of %s are reachable"), oid_to_hex(&obj->oid));
 
 			if (obj->type == OBJ_TREE) {
@@ -1689,6 +1689,8 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
 			} else if (!strcmp(arg, "--check-self-contained-and-connected")) {
 				strict = 1;
 				check_self_contained_and_connected = 1;
+			} else if (!strcmp(arg, "--fsck-objects")) {
+				do_fsck_object = 1;
 			} else if (!strcmp(arg, "--verify")) {
 				verify = 1;
 			} else if (!strcmp(arg, "--verify-stat")) {

t/t5302-pack-index.sh

@@ -262,4 +262,9 @@ EOF
     grep "^warning:.* expected .tagger. line" err
 '
 
+test_expect_success 'index-pack --fsck-objects also warns upon missing tagger in tag' '
+    git index-pack --fsck-objects tag-test-${pack1}.pack 2>err &&
+    grep "^warning:.* expected .tagger. line" err
+'
+
 test_done