Merge branch 'jc/fsck-nul-in-commit' into maint

"git fsck" learned to catch NUL byte in a commit object as
potential error and warn.

* jc/fsck-nul-in-commit:
  fsck: detect and warn a commit with embedded NUL
  fsck_commit_buffer(): do not special case the last validation

fsck.c

@@ -59,6 +59,7 @@
 	FUNC(HAS_DOTGIT, WARN) \
 	FUNC(NULL_SHA1, WARN) \
 	FUNC(ZERO_PADDED_FILEMODE, WARN) \
+	FUNC(NUL_IN_COMMIT, WARN) \
 	/* infos (reported as warnings, but ignored by default) */ \
 	FUNC(BAD_TAG_NAME, INFO) \
 	FUNC(MISSING_TAGGER_ENTRY, INFO)
@@ -610,6 +611,7 @@ static int fsck_commit_buffer(struct commit *commit, const char *buffer,
 	struct commit_graft *graft;
 	unsigned parent_count, parent_line_count = 0, author_count;
 	int err;
+	const char *buffer_begin = buffer;
 
 	if (verify_headers(buffer, size, &commit->object, options))
 		return -1;
@@ -666,9 +668,17 @@ static int fsck_commit_buffer(struct commit *commit, const char *buffer,
 	err = fsck_ident(&buffer, &commit->object, options);
 	if (err)
 		return err;
-	if (!commit->tree)
-		return report(options, &commit->object, FSCK_MSG_BAD_TREE, "could not load commit's tree %s", sha1_to_hex(tree_sha1));
-
+	if (!commit->tree) {
+		err = report(options, &commit->object, FSCK_MSG_BAD_TREE, "could not load commit's tree %s", sha1_to_hex(tree_sha1));
+		if (err)
+			return err;
+	}
+	if (memchr(buffer_begin, '\0', size)) {
+		err = report(options, &commit->object, FSCK_MSG_NUL_IN_COMMIT,
+			     "NUL byte in the commit object body");
+		if (err)
+			return err;
+	}
 	return 0;
 }
 

t/t1450-fsck.sh

@@ -427,6 +427,24 @@ test_expect_success 'fsck allows .Ňit' '
 	)
 '
 
+test_expect_success 'NUL in commit' '
+	rm -fr nul-in-commit &&
+	git init nul-in-commit &&
+	(
+		cd nul-in-commit &&
+		git commit --allow-empty -m "initial commitQNUL after message" &&
+		git cat-file commit HEAD >original &&
+		q_to_nul <original >munged &&
+		git hash-object -w -t commit --stdin <munged >name &&
+		git branch bad $(cat name) &&
+
+		test_must_fail git -c fsck.nulInCommit=error fsck 2>warn.1 &&
+		grep nulInCommit warn.1 &&
+		git fsck 2>warn.2 &&
+		grep nulInCommit warn.2
+	)
+'
+
 # create a static test repo which is broken by omitting
 # one particular object ($1, which is looked up via rev-parse
 # in the new repository).