commit ac2eeeffef0b2071f39513685c4b6d594a30416d
from: Neels Hofmeyr <neels@hofmeyr.de>
date: Sun Sep 20 14:13:07 2020 UTC

myers: error handling from diff_atoms_same()

commit - b3fb46867c2efc085c584bd336b9dca9cf26a161
commit + ac2eeeffef0b2071f39513685c4b6d594a30416d
blob - c164f2277b98e6aadeed4c94b4479e596473d531
blob + f56135e983c75dc1d4d176da40de71623e9d95b9
--- lib/diff_myers.c
+++ lib/diff_myers.c
@@ -209,14 +209,16 @@ struct diff_box {
  * meeting_snake: resulting meeting point, if any.
  * Return true when a meeting point has been identified.
  */
-static bool
-diff_divide_myers_forward(struct diff_data *left, struct diff_data *right,
+static int
+diff_divide_myers_forward(bool *found_midpoint,
+			  struct diff_data *left, struct diff_data *right,
 			  int *kd_forward, int *kd_backward, int d,
 			  struct diff_box *meeting_snake)
 {
 	int delta = (int)right->atoms.len - (int)left->atoms.len;
 	int k;
 	int x;
+	*found_midpoint = false;
 
 	debug("-- %s d=%d\n", __func__, d);
 
@@ -304,9 +306,8 @@ diff_divide_myers_forward(struct diff_data *left, stru
 					       &left->atoms.head[x],
 					       &right->atoms.head[
 						xk_to_y(x, k)]);
-			if (r) {
-				abort(); // TODO: error handling
-			}
+			if (r)
+				return r;
 			if (!same)
 				break;
 			x++;
@@ -462,14 +463,15 @@ diff_divide_myers_forward(struct diff_data *left, stru
 				debug_dump_myers_graph(left, right, NULL,
 						       kd_forward, d,
 						       kd_backward, d-1);
-				return true;
+				*found_midpoint = true;
+				return 0;
 			}
 		}
 	}
 
 	debug_dump_myers_graph(left, right, NULL, kd_forward, d,
 			       kd_backward, d-1);
-	return false;
+	return 0;
 }
 
 /* Do one backwards step in the "divide and conquer" graph traversal.
@@ -494,14 +496,17 @@ diff_divide_myers_forward(struct diff_data *left, stru
  * meeting_snake: resulting meeting point, if any.
  * Return true when a meeting point has been identified.
  */
-static bool
-diff_divide_myers_backward(struct diff_data *left, struct diff_data *right,
+static int
+diff_divide_myers_backward(bool *found_midpoint,
+			   struct diff_data *left, struct diff_data *right,
 			   int *kd_forward, int *kd_backward, int d,
 			   struct diff_box *meeting_snake)
 {
 	int delta = (int)right->atoms.len - (int)left->atoms.len;
 	int c;
 	int x;
+
+	*found_midpoint = false;
 
 	debug("-- %s d=%d\n", __func__, d);
 
@@ -602,9 +607,8 @@ diff_divide_myers_backward(struct diff_data *left, str
 					       &left->atoms.head[x-1],
 					       &right->atoms.head[
 						xc_to_y(x, c, delta)-1]);
-			if (r) {
-				abort(); // TODO: error handling
-			}
+			if (r)
+				return r;
 			if (!same)
 				break;
 			x--;
@@ -738,13 +742,14 @@ diff_divide_myers_backward(struct diff_data *left, str
 				debug_dump_myers_graph(left, right, NULL,
 						       kd_forward, d,
 						       kd_backward, d);
-				return true;
+				*found_midpoint = true;
+				return 0;
 			}
 		}
 	}
 	debug_dump_myers_graph(left, right, NULL, kd_forward, d, kd_backward,
 			       d);
-	return false;
+	return 0;
 }
 
 /* Myers "Divide et Impera": tracing forwards from the start and backwards from
@@ -789,11 +794,20 @@ diff_algo_myers_divide(const struct diff_algo_config *
 	struct diff_box mid_snake = {};
 	bool found_midpoint = false;
 	for (d = 0; d <= (max/2); d++) {
+		int r;
 		debug("-- d=%d\n", d);
-		found_midpoint = diff_divide_myers_forward(left, right, kd_forward, kd_backward, d, &mid_snake);
+		r = diff_divide_myers_forward(&found_midpoint, left, right,
+					      kd_forward, kd_backward, d,
+					      &mid_snake);
+		if (r)
+			return r;
 		if (found_midpoint)
 			break;
-		found_midpoint = diff_divide_myers_backward(left, right, kd_forward, kd_backward, d, &mid_snake);
+		r = diff_divide_myers_backward(&found_midpoint, left, right,
+					       kd_forward, kd_backward, d,
+					       &mid_snake);
+		if (r)
+			return r;
 		if (found_midpoint)
 			break;
 	}