builtin/apply: make write_out_one_result() return -1 on error

To libify `git apply` functionality we have to signal errors to the
caller instead of exit()ing.

To do that in a compatible manner with the rest of the error handling
in "builtin/apply.c", write_out_one_result() should just return what
remove_file() and create_file() are returning instead of calling
exit().

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/apply.c

@@ -4287,36 +4287,29 @@ static int create_file(struct apply_state *state, struct patch *patch)
 }
 
 /* phase zero is to remove, phase one is to create */
-static void write_out_one_result(struct apply_state *state,
-				 struct patch *patch,
-				 int phase)
+static int write_out_one_result(struct apply_state *state,
+				struct patch *patch,
+				int phase)
 {
 	if (patch->is_delete > 0) {
-		if (phase == 0) {
-			if (remove_file(state, patch, 1))
-				exit(128);
-		}
-		return;
+		if (phase == 0)
+			return remove_file(state, patch, 1);
+		return 0;
 	}
 	if (patch->is_new > 0 || patch->is_copy) {
-		if (phase == 1) {
-			if (create_file(state, patch))
-				exit(128);
-		}
-		return;
+		if (phase == 1)
+			return create_file(state, patch);
+		return 0;
 	}
 	/*
 	 * Rename or modification boils down to the same
 	 * thing: remove the old, write the new
 	 */
-	if (phase == 0) {
-		if (remove_file(state, patch, patch->is_rename))
-			exit(128);
-	}
-	if (phase == 1) {
-		if (create_file(state, patch))
-			exit(128);
-	}
+	if (phase == 0)
+		return remove_file(state, patch, patch->is_rename);
+	if (phase == 1)
+		return create_file(state, patch);
+	return 0;
 }
 
 static int write_out_one_reject(struct apply_state *state, struct patch *patch)
@@ -4403,7 +4396,8 @@ static int write_out_results(struct apply_state *state, struct patch *list)
 			if (l->rejected)
 				errs = 1;
 			else {
-				write_out_one_result(state, l, phase);
+				if (write_out_one_result(state, l, phase))
+					exit(128);
 				if (phase == 1) {
 					if (write_out_one_reject(state, l))
 						errs = 1;