Fixing potential measure call with negative size value

Summary: There is a case when measure() function will be called with negative width/height because of margin/padding. This diff fixes that scenario

Reviewed By: emilsjolander

Differential Revision: D5111534

fbshipit-source-id: 99f09b85f0c6a0e5dec89a26baba8f9d560100da

tests/YGMeasureTest.cpp

@@ -39,6 +39,19 @@ static YGSize _simulate_wrapping_text(YGNodeRef node,
   };
 }
 
+static YGSize _measure_assert_negative(YGNodeRef node,
+                                       float width,
+                                       YGMeasureMode widthMode,
+                                       float height,
+                                       YGMeasureMode heightMode) {
+  EXPECT_GE(width, 0);
+  EXPECT_GE(height, 0);
+
+  return YGSize{
+    .width = 0, .height = 0,
+  };
+}
+
 TEST(YogaTest, dont_measure_single_grow_shrink_child) {
   const YGNodeRef root = YGNodeNew();
   YGNodeStyleSetWidth(root, 100);
@@ -563,3 +576,41 @@ TEST(YogaTest, can_nullify_measure_func_on_any_node) {
   ASSERT_TRUE(YGNodeGetMeasureFunc(root) == NULL);
   YGNodeFreeRecursive(root);
 }
+
+TEST(YogaTest, cant_call_negative_measure) {
+  const YGConfigRef config = YGConfigNew();
+
+  const YGNodeRef root = YGNodeNewWithConfig(config);
+  YGNodeStyleSetFlexDirection(root, YGFlexDirectionColumn);
+  YGNodeStyleSetWidth(root, 50);
+  YGNodeStyleSetHeight(root, 10);
+
+  const YGNodeRef root_child0 = YGNodeNewWithConfig(config);
+  YGNodeSetMeasureFunc(root_child0, _measure_assert_negative);
+  YGNodeStyleSetMargin(root_child0, YGEdgeTop, 20);
+  YGNodeInsertChild(root, root_child0, 0);
+
+  YGNodeCalculateLayout(root, YGUndefined, YGUndefined, YGDirectionLTR);
+
+  YGNodeFreeRecursive(root);
+  YGConfigFree(config);
+}
+
+TEST(YogaTest, cant_call_negative_measure_horizontal) {
+  const YGConfigRef config = YGConfigNew();
+
+  const YGNodeRef root = YGNodeNewWithConfig(config);
+  YGNodeStyleSetFlexDirection(root, YGFlexDirectionRow);
+  YGNodeStyleSetWidth(root, 10);
+  YGNodeStyleSetHeight(root, 20);
+
+  const YGNodeRef root_child0 = YGNodeNewWithConfig(config);
+  YGNodeSetMeasureFunc(root_child0, _measure_assert_negative);
+  YGNodeStyleSetMargin(root_child0, YGEdgeStart, 20);
+  YGNodeInsertChild(root, root_child0, 0);
+
+  YGNodeCalculateLayout(root, YGUndefined, YGUndefined, YGDirectionLTR);
+
+  YGNodeFreeRecursive(root);
+  YGConfigFree(config);
+}

yoga/Yoga.c

@@ -1736,8 +1736,13 @@ static void YGNodeWithMeasureFuncSetMeasuredDimensions(const YGNodeRef node,
   const float marginAxisRow = YGNodeMarginForAxis(node, YGFlexDirectionRow, availableWidth);
   const float marginAxisColumn = YGNodeMarginForAxis(node, YGFlexDirectionColumn, availableWidth);
 
-  const float innerWidth = availableWidth - marginAxisRow - paddingAndBorderAxisRow;
-  const float innerHeight = availableHeight - marginAxisColumn - paddingAndBorderAxisColumn;
+  // We want to make sure we don't call measure with negative size
+  const float innerWidth = YGFloatIsUndefined(availableWidth)
+                            ? availableWidth
+                            : fmaxf(0, availableWidth - marginAxisRow - paddingAndBorderAxisRow);
+  const float innerHeight = YGFloatIsUndefined(availableHeight)
+                            ? availableHeight
+                            : fmaxf(0, availableHeight - marginAxisColumn - paddingAndBorderAxisColumn);
 
   if (widthMeasureMode == YGMeasureModeExactly && heightMeasureMode == YGMeasureModeExactly) {
     // Don't bother sizing the text if both dimensions are already defined.