Merge branch 'jk/maint-tag-show-fixes' into maint

* jk/maint-tag-show-fixes:
  tag: do not show non-tag contents with "-n"
  tag: die when listing missing or corrupt objects
  tag: fix output of "tag -n" when errors occur

Conflicts:
	t/t7004-tag.sh

builtin/tag.c

@@ -83,18 +83,51 @@ static int contains(struct commit *candidate, const struct commit_list *want)
 	return contains_recurse(candidate, want);
 }
 
+static void show_tag_lines(const unsigned char *sha1, int lines)
+{
+	int i;
+	unsigned long size;
+	enum object_type type;
+	char *buf, *sp, *eol;
+	size_t len;
+
+	buf = read_sha1_file(sha1, &type, &size);
+	if (!buf)
+		die_errno("unable to read object %s", sha1_to_hex(sha1));
+	if (type != OBJ_COMMIT && type != OBJ_TAG)
+		goto free_return;
+	if (!size)
+		die("an empty %s object %s?",
+		    typename(type), sha1_to_hex(sha1));
+
+	/* skip header */
+	sp = strstr(buf, "\n\n");
+	if (!sp)
+		goto free_return;
+
+	/* only take up to "lines" lines, and strip the signature from a tag */
+	if (type == OBJ_TAG)
+		size = parse_signature(buf, size);
+	for (i = 0, sp += 2; i < lines && sp < buf + size; i++) {
+		if (i)
+			printf("\n    ");
+		eol = memchr(sp, '\n', size - (sp - buf));
+		len = eol ? eol - sp : size - (sp - buf);
+		fwrite(sp, len, 1, stdout);
+		if (!eol)
+			break;
+		sp = eol + 1;
+	}
+free_return:
+	free(buf);
+}
+
 static int show_reference(const char *refname, const unsigned char *sha1,
 			  int flag, void *cb_data)
 {
 	struct tag_filter *filter = cb_data;
 
 	if (match_pattern(filter->patterns, refname)) {
-		int i;
-		unsigned long size;
-		enum object_type type;
-		char *buf, *sp, *eol;
-		size_t len;
-
 		if (filter->with_commit) {
 			struct commit *commit;
 
@@ -110,33 +143,8 @@ static int show_reference(const char *refname, const unsigned char *sha1,
 			return 0;
 		}
 		printf("%-15s ", refname);
-
-		buf = read_sha1_file(sha1, &type, &size);
-		if (!buf || !size)
-			return 0;
-
-		/* skip header */
-		sp = strstr(buf, "\n\n");
-		if (!sp) {
-			free(buf);
-			return 0;
-		}
-		/* only take up to "lines" lines, and strip the signature */
-		size = parse_signature(buf, size);
-		for (i = 0, sp += 2;
-				i < filter->lines && sp < buf + size;
-				i++) {
-			if (i)
-				printf("\n    ");
-			eol = memchr(sp, '\n', size - (sp - buf));
-			len = eol ? eol - sp : size - (sp - buf);
-			fwrite(sp, len, 1, stdout);
-			if (!eol)
-				break;
-			sp = eol + 1;
-		}
+		show_tag_lines(sha1, filter->lines);
 		putchar('\n');
-		free(buf);
 	}
 
 	return 0;

t/t7004-tag.sh

@@ -586,6 +586,19 @@ test_expect_success \
 	test_cmp expect actual
 '
 
+test_expect_success 'annotations for blobs are empty' '
+	blob=$(git hash-object -w --stdin <<-\EOF
+	Blob paragraph 1.
+
+	Blob paragraph 2.
+	EOF
+	) &&
+	git tag tag-blob $blob &&
+	echo "tag-blob        " >expect &&
+	git tag -n1 -l tag-blob >actual &&
+	test_cmp expect actual
+'
+
 # trying to verify annotated non-signed tags:
 
 test_expect_success GPG \