saturate some irect ops for fuzzers

Bug: skia:
Change-Id: I1c4f879a455048652abb619814841cd687a0474a
Reviewed-on: https://skia-review.googlesource.com/101881
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Reed <reed@google.com>

4 files changed, 69 insertions, 46 deletions

diff --git a/include/core/SkRect.h b/include/core/SkRect.h
index b09e53997b..0153d8ceb6 100644
--- a/include/core/SkRect.h
+++ b/include/core/SkRect.h
@@ -10,7 +10,7 @@
 
 #include "SkPoint.h"
 #include "SkSize.h"
-#include "../private/SkPedanticMath.h"
+#include "../private/SkSafe32.h"
 #include "../private/SkTFitsIn.h"
 
 struct SkRect;
@@ -96,7 +96,8 @@ struct SK_API SkIRect {
         @param b  integer stored in fBottom
         @return   bounds (l, t, r, b)
     */
-    static constexpr SkIRect SK_WARN_UNUSED_RESULT MakeLTRB(int32_t l, int32_t t, int32_t r, int32_t b) {
+    static constexpr SkIRect SK_WARN_UNUSED_RESULT MakeLTRB(int32_t l, int32_t t,
+                                                            int32_t r, int32_t b) {
         return SkIRect{l, t, r, b};
     }
 
@@ -109,8 +110,9 @@ struct SK_API SkIRect {
         @param h  added to y and stored in fBottom
         @return   bounds at (x, y) with width w and height h
     */
-    static constexpr SkIRect SK_WARN_UNUSED_RESULT MakeXYWH(int32_t x, int32_t y, int32_t w, int32_t h) {
-        return SkIRect{x, y, x + w, y + h};
+    static constexpr SkIRect SK_WARN_UNUSED_RESULT MakeXYWH(int32_t x, int32_t y,
+                                                            int32_t w, int32_t h) {
+        return { x, y, Sk32_sat_add(x, w), Sk32_sat_add(y, h) };
     }
 
     /** Returns left edge of SkIRect, if sorted.
@@ -160,14 +162,14 @@ struct SK_API SkIRect {
 
         @return  fRight minus fLeft
     */
-    int32_t width() const { return SkSub32(fRight, fLeft); }
+    int32_t width() const { return Sk32_can_overflow_sub(fRight, fLeft); }
 
     /** Returns span on the y-axis. This does not check if SkIRect is sorted, or if
         result fits in 32-bit signed integer; result may be negative.
 
         @return  fBottom minus fTop
     */
-    int32_t height() const { return SkSub32(fBottom, fTop); }
+    int32_t height() const { return Sk32_can_overflow_sub(fBottom, fTop); }
 
     /** Returns spans on the x-axis and y-axis. This does not check if SkIRect is sorted,
         or if result fits in 32-bit signed integer; result may be negative.
@@ -183,7 +185,7 @@ struct SK_API SkIRect {
 
         @return  midpoint in x
     */
-    int32_t centerX() const { return (fRight + fLeft) >> 1; }
+    int32_t centerX() const { return SkToS32(((int64_t)fRight + fLeft) >> 1); }
 
     /** Returns average of top edge and bottom edge. Result does not change if SkRect
         is sorted. Result may be incorrect if SkRect is far from the origin.
@@ -192,7 +194,7 @@ struct SK_API SkIRect {
 
         @return  midpoint in y
     */
-    int32_t centerY() const { return (fBottom + fTop) >> 1; }
+    int32_t centerY() const { return SkToS32(((int64_t)fBottom + fTop) >> 1); }
 
     int64_t width64() const { return (int64_t)fRight - (int64_t)fLeft; }
     int64_t height64() const { return (int64_t)fBottom - (int64_t)fTop; }
@@ -294,10 +296,10 @@ struct SK_API SkIRect {
         @param height  added to y and stored in fBottom
     */
     void setXYWH(int32_t x, int32_t y, int32_t width, int32_t height) {
-        fLeft = x;
-        fTop = y;
-        fRight = x + width;
-        fBottom = y + height;
+        fLeft   = x;
+        fTop    = y;
+        fRight  = Sk32_sat_add(x, width);
+        fBottom = Sk32_sat_add(y, height);
     }
 
     /** Returns SkIRect offset by (dx, dy).
@@ -312,7 +314,10 @@ struct SK_API SkIRect {
         @return    SkRect offset in x or y, with original width and height
     */
     SkIRect makeOffset(int32_t dx, int32_t dy) const {
-        return MakeLTRB(fLeft + dx, fTop + dy, fRight + dx, fBottom + dy);
+        return {
+            Sk32_sat_add(fLeft,  dx), Sk32_sat_add(fTop,    dy),
+            Sk32_sat_add(fRight, dx), Sk32_sat_add(fBottom, dy),
+        };
     }
 
     /** Returns SkIRect, inset by (dx, dy).
@@ -327,7 +332,10 @@ struct SK_API SkIRect {
         @return    SkRect inset symmetrically left and right, top and bottom
     */
     SkIRect makeInset(int32_t dx, int32_t dy) const {
-        return MakeLTRB(fLeft + dx, fTop + dy, fRight - dx, fBottom - dy);
+        return {
+            Sk32_sat_add(fLeft,  dx), Sk32_sat_add(fTop,    dy),
+            Sk32_sat_sub(fRight, dx), Sk32_sat_sub(fBottom, dy),
+        };
     }
 
     /** Returns SkIRect, outset by (dx, dy).
@@ -342,7 +350,10 @@ struct SK_API SkIRect {
         @return    SkRect outset symmetrically left and right, top and bottom
     */
     SkIRect makeOutset(int32_t dx, int32_t dy) const {
-        return MakeLTRB(fLeft - dx, fTop - dy, fRight + dx, fBottom + dy);
+        return {
+            Sk32_sat_sub(fLeft,  dx), Sk32_sat_sub(fTop,    dy),
+            Sk32_sat_add(fRight, dx), Sk32_sat_add(fBottom, dy),
+        };
     }
 
     /** Offsets SkIRect by adding dx to fLeft, fRight; and by adding dy to fTop, fBottom.
@@ -356,10 +367,10 @@ struct SK_API SkIRect {
         @param dy  offset added to fTop and fBottom
     */
     void offset(int32_t dx, int32_t dy) {
-        fLeft   += dx;
-        fTop    += dy;
-        fRight  += dx;
-        fBottom += dy;
+        fLeft   = Sk32_sat_add(fLeft,   dx);
+        fTop    = Sk32_sat_add(fTop,    dy);
+        fRight  = Sk32_sat_add(fRight,  dx);
+        fBottom = Sk32_sat_add(fBottom, dy);
     }
 
     /** Offsets SkIRect by adding delta.fX to fLeft, fRight; and by adding delta.fY to
@@ -383,10 +394,10 @@ struct SK_API SkIRect {
         @param newY  stored in fTop, preserving height()
     */
     void offsetTo(int32_t newX, int32_t newY) {
-        fRight += newX - fLeft;
-        fBottom += newY - fTop;
-        fLeft = newX;
-        fTop = newY;
+        fRight  = Sk64_pin_to_s32((int64_t)fRight + newX - fLeft);
+        fBottom = Sk64_pin_to_s32((int64_t)fBottom + newY - fTop);
+        fLeft   = newX;
+        fTop    = newY;
     }
 
     /** Insets SkIRect by (dx,dy).
@@ -400,10 +411,10 @@ struct SK_API SkIRect {
         @param dy  offset added to fTop and subtracted from fBottom
     */
     void inset(int32_t dx, int32_t dy) {
-        fLeft   += dx;
-        fTop    += dy;
-        fRight  -= dx;
-        fBottom -= dy;
+        fLeft   = Sk32_sat_add(fLeft,   dx);
+        fTop    = Sk32_sat_add(fTop,    dy);
+        fRight  = Sk32_sat_sub(fRight,  dx);
+        fBottom = Sk32_sat_sub(fBottom, dy);
     }
 
     /** Outsets SkIRect by (dx, dy).
diff --git a/include/private/SkPedanticMath.h b/include/private/SkPedanticMath.h
deleted file mode 100644
index 6d9c8a18be..0000000000
--- a/include/private/SkPedanticMath.h
+++ /dev/null
@@ -1,17 +0,0 @@
-/*
- * Copyright 2018 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#ifndef SkPedanticMath_DEFINED
-#define SkPedanticMath_DEFINED
-
-// To avoid UBSAN complaints about 2's compliment overflows
-//
-static inline int32_t SkSub32(int32_t a, int32_t b) {
-    return (int32_t)((uint32_t)a - (uint32_t)b);
-}
-
-#endif
diff --git a/include/private/SkSafe32.h b/include/private/SkSafe32.h
new file mode 100644
index 0000000000..40d4121b52
--- /dev/null
+++ b/include/private/SkSafe32.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkSafe32_DEFINED
+#define SkSafe32_DEFINED
+
+static constexpr int32_t Sk64_pin_to_s32(int64_t x) {
+    return x < SK_MinS32 ? SK_MinS32 : (x > SK_MaxS32 ? SK_MaxS32 : x);
+}
+
+static constexpr int32_t Sk32_sat_add(int32_t a, int32_t b) {
+    return Sk64_pin_to_s32((int64_t)a + (int64_t)b);
+}
+
+static constexpr int32_t Sk32_sat_sub(int32_t a, int32_t b) {
+    return Sk64_pin_to_s32((int64_t)a - (int64_t)b);
+}
+
+// To avoid UBSAN complaints about 2's compliment overflows
+//
+static constexpr int32_t Sk32_can_overflow_sub(int32_t a, int32_t b) {
+    return (int32_t)((uint32_t)a - (uint32_t)b);
+}
+
+#endif
diff --git a/src/effects/SkOffsetImageFilter.cpp b/src/effects/SkOffsetImageFilter.cpp
index a833987185..1141bfa281 100644
--- a/src/effects/SkOffsetImageFilter.cpp
+++ b/src/effects/SkOffsetImageFilter.cpp
@@ -44,8 +44,8 @@ sk_sp<SkSpecialImage> SkOffsetImageFilter::onFilterImage(SkSpecialImage* source,
     SkIPoint vec = map_offset_vector(ctx.ctm(), fOffset);
 
     if (!this->cropRectIsSet()) {
-        offset->fX = srcOffset.fX + vec.fX;
-        offset->fY = srcOffset.fY + vec.fY;
+        offset->fX = Sk32_sat_add(srcOffset.fX, vec.fX);
+        offset->fY = Sk32_sat_add(srcOffset.fY, vec.fY);
         return input;
     } else {
         SkIRect bounds;