builtin/apply: make gitdiff_*() return 1 at end of header

The gitdiff_*() functions that are called as p->fn() in parse_git_header()
should return 1 instead of -1 in case of end of header or unrecognized
input, as these are not real errors. It just instructs the parser to break
out.

This makes it possible for gitdiff_*() functions to return -1 in case of a
real error. This will be done in a following patch.

Helped-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/apply.c

@@ -812,7 +812,7 @@ static int gitdiff_hdrend(struct apply_state *state,
 			  const char *line,
 			  struct patch *patch)
 {
-	return -1;
+	return 1;
 }
 
 /*
@@ -1016,7 +1016,7 @@ static int gitdiff_unrecognized(struct apply_state *state,
 				const char *line,
 				struct patch *patch)
 {
-	return -1;
+	return 1;
 }
 
 /*
@@ -1248,9 +1248,13 @@ static int parse_git_header(struct apply_state *state,
 		for (i = 0; i < ARRAY_SIZE(optable); i++) {
 			const struct opentry *p = optable + i;
 			int oplen = strlen(p->str);
+			int res;
 			if (len < oplen || memcmp(p->str, line, oplen))
 				continue;
-			if (p->fn(state, line + oplen, patch) < 0)
+			res = p->fn(state, line + oplen, patch);
+			if (res < 0)
+				return -1;
+			if (res > 0)
 				return offset;
 			break;
 		}
@@ -1430,6 +1434,8 @@ static int find_header(struct apply_state *state,
 		 */
 		if (!memcmp("diff --git ", line, 11)) {
 			int git_hdr_len = parse_git_header(state, line, len, size, patch);
+			if (git_hdr_len < 0)
+				return -128;
 			if (git_hdr_len <= len)
 				continue;
 			if (!patch->old_name && !patch->new_name) {