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

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

To do that in a compatible manner with the rest of the error handling
in "builtin/apply.c", remove_file() should return -1 instead of
calling die().

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

builtin/apply.c

@@ -4085,17 +4085,18 @@ static void patch_stats(struct apply_state *state, struct patch *patch)
 	}
 }
 
-static void remove_file(struct apply_state *state, struct patch *patch, int rmdir_empty)
+static int remove_file(struct apply_state *state, struct patch *patch, int rmdir_empty)
 {
 	if (state->update_index) {
 		if (remove_file_from_cache(patch->old_name) < 0)
-			die(_("unable to remove %s from index"), patch->old_name);
+			return error(_("unable to remove %s from index"), patch->old_name);
 	}
 	if (!state->cached) {
 		if (!remove_or_warn(patch->old_mode, patch->old_name) && rmdir_empty) {
 			remove_path(patch->old_name);
 		}
 	}
+	return 0;
 }
 
 static void add_index_file(struct apply_state *state,
@@ -4274,8 +4275,10 @@ static void write_out_one_result(struct apply_state *state,
 				 int phase)
 {
 	if (patch->is_delete > 0) {
-		if (phase == 0)
-			remove_file(state, patch, 1);
+		if (phase == 0) {
+			if (remove_file(state, patch, 1))
+				exit(128);
+		}
 		return;
 	}
 	if (patch->is_new > 0 || patch->is_copy) {
@@ -4287,8 +4290,10 @@ static void write_out_one_result(struct apply_state *state,
 	 * Rename or modification boils down to the same
 	 * thing: remove the old, write the new
 	 */
-	if (phase == 0)
-		remove_file(state, patch, patch->is_rename);
+	if (phase == 0) {
+		if (remove_file(state, patch, patch->is_rename))
+			exit(128);
+	}
 	if (phase == 1)
 		create_file(state, patch);
 }