Avoid possible memory leak with inner blurs.

If the inner blur dst is too big, SkBlurMask::BoxBlur can return without
freeing the intermediate blur mask. Fix this by using SkAutoMaskFreeImage.

Use SkAutoMaskFreeImage instead of custom SkAutoTCallVProc in
SkBlurMask::BlurGroundTruth.

Make SkAutoMaskFreeImage a special kind of std::unique_ptr.

Change-Id: I93dc54265416ca69254633b00f14be75009d990f
Reviewed-on: https://skia-review.googlesource.com/127402
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Ben Wagner <bungeman@google.com>

2 files changed, 7 insertions, 23 deletions

diff --git a/src/core/SkBlurMask.cpp b/src/core/SkBlurMask.cpp
index 04fd92292b..f4fa100961 100644
--- a/src/core/SkBlurMask.cpp
+++ b/src/core/SkBlurMask.cpp
@@ -205,6 +205,7 @@ bool SkBlurMask::BoxBlur(SkMask* dst, const SkMask& src, SkScalar sigma, SkBlurS
         case kInner_SkBlurStyle: {
             // now we allocate the "real" dst, mirror the size of src
             SkMask blur = *dst;
+            SkAutoMaskFreeImage autoFreeBlurMask(blur.fImage);
             dst->fBounds = src.fBounds;
             dst->fRowBytes = dst->fBounds.width();
             size_t dstSize = dst->computeImageSize();
@@ -247,7 +248,6 @@ bool SkBlurMask::BoxBlur(SkMask* dst, const SkMask& src, SkScalar sigma, SkBlurS
                 default:
                     SK_ABORT("Unhandled format.");
             };
-            SkMask::FreeImage(blur.fImage);
         } break;
     }
 
@@ -547,7 +547,7 @@ bool SkBlurMask::BlurGroundTruth(SkScalar sigma, SkMask* dst, const SkMask& src,
 
         const uint8_t*  srcPixels = src.fImage;
         uint8_t*        dstPixels = SkMask::AllocImage(dstSize);
-        SkAutoTCallVProc<uint8_t, SkMask_FreeImage> autoCall(dstPixels);
+        SkAutoMaskFreeImage autoFreeDstPixels(dstPixels);
 
         // do the actual blur.  First, make a padded copy of the source.
         // use double pad so we never have to check if we're outside anything
@@ -637,7 +637,7 @@ bool SkBlurMask::BlurGroundTruth(SkScalar sigma, SkMask* dst, const SkMask& src,
                 SkMask::FreeImage(dstPixels);
             } break;
         };
-        (void)autoCall.release();
+        autoFreeDstPixels.release();
     }
 
     if (style == kInner_SkBlurStyle) {
diff --git a/src/core/SkMask.h b/src/core/SkMask.h
index 395eecc44b..337664d9da 100644
--- a/src/core/SkMask.h
+++ b/src/core/SkMask.h
@@ -14,6 +14,8 @@
 #include "SkRect.h"
 #include "SkTemplates.h"
 
+#include <memory>
+
 /** \class SkMask
     SkMask is used to describe alpha bitmaps, either 1bit, 8bit, or
     the 3-channel 3D format. These are passed to SkMaskFilter objects.
@@ -229,30 +231,12 @@ template <> struct SkMask::AlphaIter<SkMask::kLCD16_Format> {
 ///////////////////////////////////////////////////////////////////////////////
 
 /**
- *  \class SkAutoMaskImage
+ *  \using SkAutoMaskImage
  *
  *  Stack class used to manage the fImage buffer in a SkMask.
  *  When this object loses scope, the buffer is freed with SkMask::FreeImage().
  */
-class SkAutoMaskFreeImage {
-public:
-    SkAutoMaskFreeImage(uint8_t* maskImage) {
-        fImage = maskImage;
-    }
-
-    ~SkAutoMaskFreeImage() {
-        SkMask::FreeImage(fImage);
-    }
-
-    uint8_t* release() {
-        uint8_t* tmp = fImage;
-        fImage = nullptr;
-        return tmp;
-    }
-
-private:
-    uint8_t* fImage;
-};
+using SkAutoMaskFreeImage = std::unique_ptr<uint8_t,SkFunctionWrapper<void,void,SkMask::FreeImage>>;
 #define SkAutoMaskFreeImage(...) SK_REQUIRE_LOCAL_VAR(SkAutoMaskFreeImage)
 
 #endif