From fbf890200cfa93278259ddc87c7ae3636e85cc57 Mon Sep 17 00:00:00 2001
From: Campbell Barton <ideasman42@gmail.com>
Date: Thu, 16 May 2013 15:28:57 +0000
Subject: [PATCH] fix for crash in grid-fill where it was possible for rail
 edges to overlap.

---
 source/blender/bmesh/intern/bmesh_edgeloop.c  | 21 +++++++++++++++++++
 source/blender/bmesh/intern/bmesh_edgeloop.h  |  2 ++
 .../blender/bmesh/operators/bmo_grid_fill.c   |  6 ++++++
 3 files changed, 29 insertions(+)

diff --git a/source/blender/bmesh/intern/bmesh_edgeloop.c b/source/blender/bmesh/intern/bmesh_edgeloop.c
index 1ab7652502c..7c5b20381ab 100644
--- a/source/blender/bmesh/intern/bmesh_edgeloop.c
+++ b/source/blender/bmesh/intern/bmesh_edgeloop.c
@@ -601,3 +601,24 @@ void BM_edgeloop_expand(BMesh *UNUSED(bm), BMEdgeLoopStore *el_store, int el_sto
 
 	BLI_assert(el_store->len == el_store_len);
 }
+
+bool BM_edgeloop_overlap_check(struct BMEdgeLoopStore *el_store_a, struct BMEdgeLoopStore *el_store_b)
+{
+	LinkData *node;
+
+	/* init */
+	for (node = el_store_a->verts.first; node; node = node->next) {
+		BM_elem_flag_disable((BMVert *)node->data, BM_ELEM_INTERNAL_TAG);
+	}
+	for (node = el_store_b->verts.first; node; node = node->next) {
+		BM_elem_flag_enable((BMVert *)node->data, BM_ELEM_INTERNAL_TAG);
+	}
+
+	/* check 'a' */
+	for (node = el_store_a->verts.first; node; node = node->next) {
+		if (BM_elem_flag_test((BMVert *)node->data, BM_ELEM_INTERNAL_TAG)) {
+			return true;
+		}
+	}
+	return false;
+}
diff --git a/source/blender/bmesh/intern/bmesh_edgeloop.h b/source/blender/bmesh/intern/bmesh_edgeloop.h
index 50f85a3155b..aa57fcfc47d 100644
--- a/source/blender/bmesh/intern/bmesh_edgeloop.h
+++ b/source/blender/bmesh/intern/bmesh_edgeloop.h
@@ -57,6 +57,8 @@ void                BM_edgeloop_calc_normal(BMesh *bm, struct BMEdgeLoopStore *e
 void                BM_edgeloop_flip(BMesh *bm, struct BMEdgeLoopStore *el_store);
 void                BM_edgeloop_expand(BMesh *bm, struct BMEdgeLoopStore *el_store, int el_store_len);
 
+bool                BM_edgeloop_overlap_check(struct BMEdgeLoopStore *el_store_a, struct BMEdgeLoopStore *el_store_b);
+
 #define BM_EDGELOOP_NEXT(el_store, elink) \
 	(elink)->next ? elink->next : (BM_edgeloop_is_closed(el_store) ? BM_edgeloop_verts_get(el_store)->first : NULL)
 
diff --git a/source/blender/bmesh/operators/bmo_grid_fill.c b/source/blender/bmesh/operators/bmo_grid_fill.c
index 05116c93a13..21325cf05b2 100644
--- a/source/blender/bmesh/operators/bmo_grid_fill.c
+++ b/source/blender/bmesh/operators/bmo_grid_fill.c
@@ -423,6 +423,12 @@ void bmo_grid_fill_exec(BMesh *bm, BMOperator *op)
 		goto cleanup;
 	}
 
+	if (BM_edgeloop_overlap_check(estore_rail_a, estore_rail_b)) {
+		BMO_error_raise(bm, op, BMERR_INVALID_SELECTION,
+		                "Connecting edge loops overlap");
+		goto cleanup;
+	}
+
 	/* finally we have all edge loops needed */
 	bm_grid_fill(bm, estore_a, estore_b, estore_rail_a, estore_rail_b,
 	             mat_nr, use_smooth);