fix SkRRect fuzzer assert

fuzzer bug triggers an assert in SkRRect::isValid because
on radius is zero and the other, while small, is not.

The radii are normally both set to zero if one is zero
in SkRRect::setRectRadii. However, subsequently scaleRadii
may set one to zero when normalizing the pair.

Move the clamping code out of setRectRadii so it can be
called from scaleRadii as well.

R=reed@google.com
Bug: skia:
Change-Id: Ib9a86da7212567b2f4b83d99a41cf9ba2c30e9b9
Reviewed-on: https://skia-review.googlesource.com/115701
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Cary Clark <caryclark@google.com>

1 files changed, 29 insertions, 19 deletions

diff --git a/src/core/SkRRect.cpp b/src/core/SkRRect.cpp
index a8ed7246ef..50a87fab3c 100644
--- a/src/core/SkRRect.cpp
+++ b/src/core/SkRRect.cpp
@@ -116,40 +116,44 @@ static double compute_min_scale(double rad1, double rad2, double limit, double c
     return curMin;
 }
 
-void SkRRect::setRectRadii(const SkRect& rect, const SkVector radii[4]) {
-    if (!this->initializeRect(rect)) {
-        return;
-    }
-
-    if (!SkScalarsAreFinite(&radii[0].fX, 8)) {
-        this->setRect(rect);    // devolve into a simple rect
-        return;
-    }
-
-    memcpy(fRadii, radii, sizeof(fRadii));
-
+static bool clamp_to_zero(SkVector radii[4]) {
     bool allCornersSquare = true;
 
     // Clamp negative radii to zero
     for (int i = 0; i < 4; ++i) {
-        if (fRadii[i].fX <= 0 || fRadii[i].fY <= 0) {
+        if (radii[i].fX <= 0 || radii[i].fY <= 0) {
             // In this case we are being a little fast & loose. Since one of
             // the radii is 0 the corner is square. However, the other radii
             // could still be non-zero and play in the global scale factor
             // computation.
-            fRadii[i].fX = 0;
-            fRadii[i].fY = 0;
+            radii[i].fX = 0;
+            radii[i].fY = 0;
         } else {
             allCornersSquare = false;
         }
     }
 
-    if (allCornersSquare) {
+    return allCornersSquare;
+}
+
+void SkRRect::setRectRadii(const SkRect& rect, const SkVector radii[4]) {
+    if (!this->initializeRect(rect)) {
+        return;
+    }
+
+    if (!SkScalarsAreFinite(&radii[0].fX, 8)) {
+        this->setRect(rect);    // devolve into a simple rect
+        return;
+    }
+
+    memcpy(fRadii, radii, sizeof(fRadii));
+
+    if (clamp_to_zero(fRadii)) {
         this->setRect(rect);
         return;
     }
 
-    this->scaleRadii();
+    this->scaleRadii(rect);
 }
 
 bool SkRRect::initializeRect(const SkRect& rect) {
@@ -167,7 +171,7 @@ bool SkRRect::initializeRect(const SkRect& rect) {
     return true;
 }
 
-void SkRRect::scaleRadii() {
+void SkRRect::scaleRadii(const SkRect& rect) {
 
     // Proportionally scale down all radii to fit. Find the minimum ratio
     // of a side and the radii on that side (for all four sides) and use
@@ -196,6 +200,12 @@ void SkRRect::scaleRadii() {
         SkScaleToSides::AdjustRadii(height, scale, &fRadii[3].fY, &fRadii[0].fY);
     }
 
+    // adjust radii may set x or y to zero; set companion to zero as well
+    if (clamp_to_zero(fRadii)) {
+        this->setRect(rect);
+        return;
+    }
+
     // At this point we're either oval, simple, or complex (not empty or rect).
     this->computeType();
 
@@ -440,7 +450,7 @@ bool SkRRect::transform(const SkMatrix& matrix, SkRRect* dst) const {
         return false;
     }
 
-    dst->scaleRadii();
+    dst->scaleRadii(dst->fRect);
     dst->isValid();
 
     return true;