mktag: allow turning off fsck.extraHeaderEntry

In earlier commits mktag learned to use the fsck machinery, at which
point we needed to add fsck.extraHeaderEntry so it could be as strict
about extra headers as it's been ever since it was implemented.

But it's not nice to need to switch away from "mktag" to "hash-object"
+ manual "fsck" just because you'd like to have an extra header. So
let's support turning it off by getting "fsck.*" variables from the
config.

Pedantically speaking it's still not possible to make "mktag" behave
just like "hash-object -t tag" does, since we're unconditionally going
to check the referenced object in verify_object_in_tag(), which is our
own check, and not one that exists in fsck.c.

But the spirit of "this works like fsck" is preserved, in that if you
created such a tag with "hash-object" and did a full "fsck" on the
repository it would also error out about that invalid object, it just
wouldn't emit the same message as fsck does.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 28 insertions, 2 deletions

diff --git a/Documentation/git-mktag.txt b/Documentation/git-mktag.txt
index fa070e21a0..79813ff8df 100644
--- a/Documentation/git-mktag.txt
+++ b/Documentation/git-mktag.txt
@@ -32,7 +32,10 @@ would run by default in that all `fsck.<msg-id>` messages are promoted
 from warnings to errors (so e.g. a missing "tagger" line is an error).
 
 Extra headers in the object are also an error under mktag, but ignored
-by linkgit:git-fsck[1]
+by linkgit:git-fsck[1]. This extra check can be turned off by setting
+the appropriate `fsck.<msg-id>` varible:
+
+    git -c fsck.extraHeaderEntry=ignore mktag <my-tag-with-headers
 
 Tag Format
 ----------
diff --git a/builtin/mktag.c b/builtin/mktag.c
index 4dd35bc79e..373926d7e0 100644
--- a/builtin/mktag.c
+++ b/builtin/mktag.c
@@ -3,6 +3,14 @@
 #include "replace-object.h"
 #include "object-store.h"
 #include "fsck.h"
+#include "config.h"
+
+static struct fsck_options fsck_options = FSCK_OPTIONS_STRICT;
+
+static int mktag_config(const char *var, const char *value, void *cb)
+{
+	return fsck_config_internal(var, value, cb, &fsck_options);
+}
 
 static int mktag_fsck_error_func(struct fsck_options *o,
 				 const struct object_id *oid,
@@ -53,7 +61,6 @@ static int verify_object_in_tag(struct object_id *tagged_oid, int *tagged_type)
 int cmd_mktag(int argc, const char **argv, const char *prefix)
 {
 	struct strbuf buf = STRBUF_INIT;
-	struct fsck_options fsck_options = FSCK_OPTIONS_STRICT;
 	struct object_id tagged_oid;
 	int tagged_type;
 	struct object_id result;
@@ -66,6 +73,8 @@ int cmd_mktag(int argc, const char **argv, const char *prefix)
 
 	fsck_options.error_func = mktag_fsck_error_func;
 	fsck_set_msg_type(&fsck_options, "extraheaderentry", "warn");
+	/* config might set fsck.extraHeaderEntry=* again */
+	git_config(mktag_config, NULL);
 	if (fsck_tag_standalone(NULL, buf.buf, buf.len, &fsck_options,
 				&tagged_oid, &tagged_type))
 		die("tag on stdin did not pass our strict fsck check");
diff --git a/t/t3800-mktag.sh b/t/t3800-mktag.sh
index 5e96f69e69..929bb9f492 100755
--- a/t/t3800-mktag.sh
+++ b/t/t3800-mktag.sh
@@ -412,6 +412,20 @@ EOF
 check_verify_failure 'detect invalid header entry' \
 	'^error:.* extraHeaderEntry:'
 
+test_expect_success 'invalid header entry config & fsck' '
+	test_must_fail git mktag <tag.sig &&
+	test_must_fail git -c fsck.extraHeaderEntry=error mktag <tag.sig &&
+	test_must_fail git -c fsck.extraHeaderEntry=warn mktag <tag.sig &&
+	git -c fsck.extraHeaderEntry=ignore mktag <tag.sig &&
+	git fsck &&
+	env GIT_TEST_GETTEXT_POISON=false \
+		git -c fsck.extraHeaderEntry=warn fsck 2>err &&
+	grep "warning .*extraHeaderEntry:" err &&
+	test_must_fail env GIT_TEST_GETTEXT_POISON=false \
+		git -c fsck.extraHeaderEntry=error 2>err fsck &&
+	grep "error .* extraHeaderEntry:" err
+'
+
 cat >tag.sig <<EOF
 object $head
 type commit