Merge branch 'jk/verify-sig-merge-into-void'

"git merge" and "git pull" that merges into an unborn branch used
to completely ignore "--verify-signatures", which has been
corrected.

* jk/verify-sig-merge-into-void:
  pull: handle --verify-signatures for unborn branch
  merge: handle --verify-signatures for unborn branch
  merge: extract verify_merge_signature() helper

builtin/merge.c

@@ -1337,6 +1337,10 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			die(_("%s - not something we can merge"), argv[0]);
 		if (remoteheads->next)
 			die(_("Can merge only exactly one commit into empty head"));
+
+		if (verify_signatures)
+			verify_merge_signature(remoteheads->item, verbosity);
+
 		remote_head_oid = &remoteheads->item->object.oid;
 		read_empty(remote_head_oid, 0);
 		update_ref("initial pull", "HEAD", remote_head_oid, NULL, 0,
@@ -1358,31 +1362,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	if (verify_signatures) {
 		for (p = remoteheads; p; p = p->next) {
-			struct commit *commit = p->item;
-			char hex[GIT_MAX_HEXSZ + 1];
-			struct signature_check signature_check;
-			memset(&signature_check, 0, sizeof(signature_check));
-
-			check_commit_signature(commit, &signature_check);
-
-			find_unique_abbrev_r(hex, &commit->object.oid, DEFAULT_ABBREV);
-			switch (signature_check.result) {
-			case 'G':
-				break;
-			case 'U':
-				die(_("Commit %s has an untrusted GPG signature, "
-				      "allegedly by %s."), hex, signature_check.signer);
-			case 'B':
-				die(_("Commit %s has a bad GPG signature "
-				      "allegedly by %s."), hex, signature_check.signer);
-			default: /* 'N' */
-				die(_("Commit %s does not have a GPG signature."), hex);
-			}
-			if (verbosity >= 0 && signature_check.result == 'G')
-				printf(_("Commit %s has a good GPG signature by %s\n"),
-				       hex, signature_check.signer);
-
-			signature_check_clear(&signature_check);
+			verify_merge_signature(p->item, verbosity);
 		}
 	}

builtin/pull.c

@@ -557,6 +557,17 @@ static int run_fetch(const char *repo, const char **refspecs)
 static int pull_into_void(const struct object_id *merge_head,
 		const struct object_id *curr_head)
 {
+	if (opt_verify_signatures) {
+		struct commit *commit;
+
+		commit = lookup_commit(the_repository, merge_head);
+		if (!commit)
+			die(_("unable to access commit %s"),
+			    oid_to_hex(merge_head));
+
+		verify_merge_signature(commit, opt_verbosity);
+	}
+
 	/*
 	 * Two-way merge: we treat the index as based on an empty tree,
 	 * and try to fast-forward to HEAD. This ensures we will not lose

commit.c

@@ -1099,7 +1099,33 @@ int check_commit_signature(const struct commit *commit, struct signature_check *
 	return ret;
 }
+void verify_merge_signature(struct commit *commit, int verbosity)
+{
+	char hex[GIT_MAX_HEXSZ + 1];
+	struct signature_check signature_check;
+	memset(&signature_check, 0, sizeof(signature_check));
+
+	check_commit_signature(commit, &signature_check);
+
+	find_unique_abbrev_r(hex, &commit->object.oid, DEFAULT_ABBREV);
+	switch (signature_check.result) {
+	case 'G':
+		break;
+	case 'U':
+		die(_("Commit %s has an untrusted GPG signature, "
+		      "allegedly by %s."), hex, signature_check.signer);
+	case 'B':
+		die(_("Commit %s has a bad GPG signature "
+		      "allegedly by %s."), hex, signature_check.signer);
+	default: /* 'N' */
+		die(_("Commit %s does not have a GPG signature."), hex);
+	}
+	if (verbosity >= 0 && signature_check.result == 'G')
+		printf(_("Commit %s has a good GPG signature by %s\n"),
+		       hex, signature_check.signer);
+	signature_check_clear(&signature_check);
+}
 void append_merge_tag_headers(struct commit_list *parents,
 			      struct commit_extra_header ***tail)

commit.h

@@ -340,6 +340,14 @@ void record_author_date(struct author_date_slab *author_date,
 			struct commit *commit);
 int compare_commits_by_author_date(const void *a_, const void *b_, void *unused);
+
+/*
+ * Verify a single commit with check_commit_signature() and die() if it is not
+ * a good signature. This isn't really suitable for general use, but is a
+ * helper to implement consistent logic for pull/merge --verify-signatures.
+ */
+void verify_merge_signature(struct commit *commit, int verbose);
+
 int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused);
 int compare_commits_by_gen_then_commit_date(const void *a_, const void *b_, void *unused);

t/t5573-pull-verify-signatures.sh

@@ -78,4 +78,11 @@ test_expect_success GPG 'pull commit with bad signature with --no-verify-signatu
 	git pull --ff-only --no-verify-signatures bad 2>pullerror
 '
+test_expect_success GPG 'pull unsigned commit into unborn branch' '
+	git init empty-repo &&
+	test_must_fail \
+		git -C empty-repo pull --verify-signatures ..  2>pullerror &&
+	test_i18ngrep "does not have a GPG signature" pullerror
+'
+
 test_done

t/t7612-merge-verify-signatures.sh

@@ -103,4 +103,11 @@ test_expect_success GPG 'merge commit with bad signature with merge.verifySignat
 	git merge --no-verify-signatures $(cat forged.commit)
 '
+test_expect_success GPG 'merge unsigned commit into unborn branch' '
+	test_when_finished "git checkout initial" &&
+	git checkout --orphan unborn &&
+	test_must_fail git merge --verify-signatures side-unsigned 2>mergeerror &&
+	test_i18ngrep "does not have a GPG signature" mergeerror
+'
+
 test_done