fsck: disallow demoting grave fsck errors to warnings

Some kinds of errors are intrinsically unrecoverable (e.g. errors while
uncompressing objects). It does not make sense to allow demoting them to
mere warnings.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

fsck.c

@@ -9,7 +9,12 @@
 #include "refs.h"
 #include "utf8.h"
 
+#define FSCK_FATAL -1
+
 #define FOREACH_MSG_ID(FUNC) \
+	/* fatal errors */ \
+	FUNC(NUL_IN_HEADER, FATAL) \
+	FUNC(UNTERMINATED_HEADER, FATAL) \
 	/* errors */ \
 	FUNC(BAD_DATE, ERROR) \
 	FUNC(BAD_DATE_OVERFLOW, ERROR) \
@@ -39,11 +44,9 @@
 	FUNC(MISSING_TYPE, ERROR) \
 	FUNC(MISSING_TYPE_ENTRY, ERROR) \
 	FUNC(MULTIPLE_AUTHORS, ERROR) \
-	FUNC(NUL_IN_HEADER, ERROR) \
 	FUNC(TAG_OBJECT_NOT_TAG, ERROR) \
 	FUNC(TREE_NOT_SORTED, ERROR) \
 	FUNC(UNKNOWN_TYPE, ERROR) \
-	FUNC(UNTERMINATED_HEADER, ERROR) \
 	FUNC(ZERO_PADDED_DATE, ERROR) \
 	/* warnings */ \
 	FUNC(BAD_FILEMODE, WARN) \
@@ -149,6 +152,9 @@ void fsck_set_msg_type(struct fsck_options *options,
 		die("Unhandled message id: %s", msg_id);
 	type = parse_msg_type(msg_type);
 
+	if (type != FSCK_ERROR && msg_id_info[id].msg_type == FSCK_FATAL)
+		die("Cannot demote %s to %s", msg_id, msg_type);
+
 	if (!options->msg_type) {
 		int i;
 		int *msg_type = xmalloc(sizeof(int) * FSCK_MSG_MAX);
@@ -216,6 +222,9 @@ static int report(struct fsck_options *options, struct object *object,
 	struct strbuf sb = STRBUF_INIT;
 	int msg_type = fsck_msg_type(id, options), result;
 
+	if (msg_type == FSCK_FATAL)
+		msg_type = FSCK_ERROR;
+
 	append_msg_id(&sb, msg_id_info[id].id_string);
 
 	va_start(ap, fmt);

t/t5504-fetch-receive-strict.sh

@@ -136,4 +136,15 @@ test_expect_success 'push with receive.fsck.missingEmail=warn' '
 	grep "missingEmail" act
 '
 
+test_expect_success \
+	'receive.fsck.unterminatedHeader=warn triggers error' '
+	rm -rf dst &&
+	git init dst &&
+	git --git-dir=dst/.git config receive.fsckobjects true &&
+	git --git-dir=dst/.git config \
+		receive.fsck.unterminatedheader warn &&
+	test_must_fail git push --porcelain dst HEAD >act 2>&1 &&
+	grep "Cannot demote unterminatedheader" act
+'
+
 test_done