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>

4 files changed, 7 insertions, 6 deletions

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;
     }