change computeByteSize to return max_size_t on overflow

Bug: skia:7132
Change-Id: I41045640ee62b2c988a84370ead5034bbccc6daf
Reviewed-on: https://skia-review.googlesource.com/56620
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Mike Reed <reed@google.com>

9 files changed, 19 insertions, 8 deletions

diff --git a/include/core/SkImageInfo.h b/include/core/SkImageInfo.h
index 50d068a09c..cab84b9fe0 100644
--- a/include/core/SkImageInfo.h
+++ b/include/core/SkImageInfo.h
@@ -317,11 +317,19 @@ public:
     }
 #endif
 
+#ifdef SK_SUPPORT_LEGACY_COMPUTEBYTESIZE_RET_0
     /**
      *  Returns the size (in bytes) of the image buffer that this info needs, given the specified
      *  rowBytes. The rowBytes must be >= this->minRowBytes().
      *  If the calculation overflows, or if the height is 0, this returns 0.
      */
+#else
+    /**
+     *  Returns the size (in bytes) of the image buffer that this info needs, given the specified
+     *  rowBytes. The rowBytes must be >= this->minRowBytes().
+     *  If the calculation overflows this returns SK_MaxSizeT
+     */
+#endif
     size_t computeByteSize(size_t rowBytes) const;
 
     /**
diff --git a/include/core/SkTypes.h b/include/core/SkTypes.h
index 63a2b40591..59bdaaa90c 100644
--- a/include/core/SkTypes.h
+++ b/include/core/SkTypes.h
@@ -233,6 +233,7 @@ template <typename D, typename S> D SkTo(S s) {
 #define SK_MaxU32   0xFFFFFFFF
 #define SK_MinU32   0
 #define SK_NaN32    ((int) (1U << 31))
+#define SK_MaxSizeT SIZE_MAX
 
 static inline int32_t SkLeftShift(int32_t value, int32_t shift) {
     return (int32_t) ((uint32_t) value << shift);
diff --git a/public.bzl b/public.bzl
index e8325500a0..dfb64707d6 100644
--- a/public.bzl
+++ b/public.bzl
@@ -656,6 +656,7 @@ DEFINES_ALL = [
     # Required for building dm.
     "GR_TEST_UTILS",
     # Staging flags for API changes
+    "SK_SUPPORT_LEGACY_COMPUTEBYTESIZE_RET_0",
     # Should remove after we update golden images
     "SK_WEBP_ENCODER_USE_DEFAULT_METHOD",
     # Experiment to diagnose image diffs in Google3
diff --git a/src/core/SkAutoPixmapStorage.cpp b/src/core/SkAutoPixmapStorage.cpp
index df0c0fa878..fb8ad00246 100644
--- a/src/core/SkAutoPixmapStorage.cpp
+++ b/src/core/SkAutoPixmapStorage.cpp
@@ -37,7 +37,7 @@ bool SkAutoPixmapStorage::tryAlloc(const SkImageInfo& info) {
 
     size_t rb;
     size_t size = AllocSize(info, &rb);
-    if (0 == size) {
+    if (SK_MaxSizeT == size) {
         return false;
     }
     void* pixels = sk_malloc_flags(size, 0);
diff --git a/src/core/SkBitmapCache.cpp b/src/core/SkBitmapCache.cpp
index 8d3991a9d5..2f163183db 100644
--- a/src/core/SkBitmapCache.cpp
+++ b/src/core/SkBitmapCache.cpp
@@ -290,7 +290,7 @@ SkBitmapCache::RecPtr SkBitmapCache::Alloc(const SkBitmapCacheDesc& desc, const
 
     const size_t rb = info.minRowBytes();
     size_t size = info.computeByteSize(rb);
-    if (0 == size) {
+    if (SK_MaxSizeT == size) {
         return nullptr;
     }
 
diff --git a/src/core/SkImageInfo.cpp b/src/core/SkImageInfo.cpp
index c610b82bdc..9e08768d7b 100644
--- a/src/core/SkImageInfo.cpp
+++ b/src/core/SkImageInfo.cpp
@@ -78,7 +78,11 @@ size_t SkImageInfo::computeByteSize(size_t rowBytes) const {
     SkSafeMath safe;
     size_t bytes = safe.add(safe.mul(fHeight - 1, rowBytes),
                             safe.mul(fWidth, this->bytesPerPixel()));
+#ifdef SK_SUPPORT_LEGACY_COMPUTEBYTESIZE_RET_0
     return safe ? bytes : 0;
+#else
+    return safe ? bytes : SK_MaxSizeT;
+#endif
 }
 
 static bool alpha_type_is_valid(SkAlphaType alphaType) {
diff --git a/src/core/SkMallocPixelRef.cpp b/src/core/SkMallocPixelRef.cpp
index 10861028b1..531d9f8fdf 100644
--- a/src/core/SkMallocPixelRef.cpp
+++ b/src/core/SkMallocPixelRef.cpp
@@ -80,7 +80,7 @@ sk_sp<SkPixelRef> SkMallocPixelRef::MakeUsing(void*(*allocProc)(size_t),
     size_t size = 0;
     if (!info.isEmpty() && rowBytes) {
         size = info.computeByteSize(rowBytes);
-        if (!size) {
+        if (size == SK_MaxSizeT) {
             return nullptr; // overflow
         }
     }
@@ -131,9 +131,6 @@ sk_sp<SkPixelRef> SkMallocPixelRef::MakeWithData(const SkImageInfo& info,
     if (!is_valid(info)) {
         return nullptr;
     }
-    // TODO: what should we return if computeByteSize returns 0?
-    // - the info was empty?
-    // - we overflowed computing the size?
     if ((rowBytes < info.minRowBytes()) || (data->size() < info.computeByteSize(rowBytes))) {
         return nullptr;
     }
diff --git a/src/image/SkImage.cpp b/src/image/SkImage.cpp
index 705efaec30..c67b6e4cdb 100644
--- a/src/image/SkImage.cpp
+++ b/src/image/SkImage.cpp
@@ -423,7 +423,7 @@ sk_sp<SkImage> SkImageMakeRasterCopyAndAssignColorSpace(const SkImage* src,
 
     size_t rowBytes = info.minRowBytes();
     size_t size = info.computeByteSize(rowBytes);
-    if (size == 0) {
+    if (size == SK_MaxSizeT) {
         return nullptr;
     }
     auto data = SkData::MakeUninitialized(size);
diff --git a/src/image/SkImage_Raster.cpp b/src/image/SkImage_Raster.cpp
index c576d9d3a1..e43d2c48b7 100644
--- a/src/image/SkImage_Raster.cpp
+++ b/src/image/SkImage_Raster.cpp
@@ -62,7 +62,7 @@ public:
         }
 
         size_t size = info.computeByteSize(rowBytes);
-        if (0 == size) {
+        if (SK_MaxSizeT == size) {
             return false;
         }