Cancel image loads if decoding failed (attempt #2)

third_party/WebKit/Source/platform/image-decoders/ImageDecoder.cpp

 /*
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Library General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 62 matching lines @@
 inline bool matchesCURSignature(const char* contents)
 {
     return !memcmp(contents, "\x00\x00\x02\x00", 4);
 }
 
 inline bool matchesBMPSignature(const char* contents)
 {
     return !memcmp(contents, "BM", 2);
 }
 
-std::unique_ptr<ImageDecoder> ImageDecoder::create(const char* contents, size_t length, AlphaOption alphaOption, GammaAndColorProfileOption colorOptions)
+std::unique_ptr<ImageDecoder> ImageDecoder::create(SniffResult sniffResult, AlphaOption alphaOption, GammaAndColorProfileOption colorOptions)
 {
-    const size_t longestSignatureLength = sizeof("RIFF????WEBPVP") - 1;
-    ASSERT(longestSignatureLength == 14);
-
-    if (length < longestSignatureLength)
-        return nullptr;
-
     size_t maxDecodedBytes = Platform::current() ? Platform::current()->maxDecodedImageBytes() : noDecodedImageByteLimit;
 
-    if (matchesJPEGSignature(contents))
+    switch (sniffResult) {
+    case SniffResult::JPEG:
         return wrapUnique(new JPEGImageDecoder(alphaOption, colorOptions, maxDecodedBytes));
-
-    if (matchesPNGSignature(contents))
+    case SniffResult::PNG:
         return wrapUnique(new PNGImageDecoder(alphaOption, colorOptions, maxDecodedBytes));
-
-    if (matchesGIFSignature(contents))
+    case SniffResult::GIF:
         return wrapUnique(new GIFImageDecoder(alphaOption, colorOptions, maxDecodedBytes));
-
-    if (matchesWebPSignature(contents))
+    case SniffResult::WEBP:
         return wrapUnique(new WEBPImageDecoder(alphaOption, colorOptions, maxDecodedBytes));
-
-    if (matchesICOSignature(contents) || matchesCURSignature(contents))
+    case SniffResult::ICO:
         return wrapUnique(new ICOImageDecoder(alphaOption, colorOptions, maxDecodedBytes));
-
-    if (matchesBMPSignature(contents))
+    case SniffResult::BMP:
         return wrapUnique(new BMPImageDecoder(alphaOption, colorOptions, maxDecodedBytes));
-
+    case SniffResult::InsufficientData:
+    case SniffResult::Invalid:
+        return nullptr;
+    }
+    NOTREACHED();
     return nullptr;
 }
 
-std::unique_ptr<ImageDecoder> ImageDecoder::create(const SharedBuffer& data, AlphaOption alphaOption, GammaAndColorProfileOption colorOptions)
+ImageDecoder::SniffResult ImageDecoder::determineImageType(const char* contents, size_t length)
+{
+    const size_t longestSignatureLength = sizeof("RIFF????WEBPVP") - 1;
+    DCHECK_EQ(14u, longestSignatureLength);
+
+    if (length < longestSignatureLength)
+        return SniffResult::InsufficientData;
+    if (matchesJPEGSignature(contents))
+        return SniffResult::JPEG;
+    if (matchesPNGSignature(contents))
+        return SniffResult::PNG;
+    if (matchesGIFSignature(contents))
+        return SniffResult::GIF;
+    if (matchesWebPSignature(contents))
+        return SniffResult::WEBP;
+    if (matchesICOSignature(contents) || matchesCURSignature(contents))
+        return SniffResult::ICO;
+    if (matchesBMPSignature(contents))
+        return SniffResult::BMP;
+    return SniffResult::Invalid;
+}
+
+ImageDecoder::SniffResult ImageDecoder::determineImageType(const SharedBuffer& data)
 {
     const char* contents;
     const size_t length = data.getSomeData<size_t>(contents);
-    return create(contents, length, alphaOption, colorOptions);
+    return determineImageType(contents, length);
 }
 
-std::unique_ptr<ImageDecoder> ImageDecoder::create(const SegmentReader& data, AlphaOption alphaOption, GammaAndColorProfileOption colorOptions)
+ImageDecoder::SniffResult ImageDecoder::determineImageType(const SegmentReader& data)
 {
     const char* contents;
     const size_t length = data.getSomeData(contents, 0);
-    return create(contents, length, alphaOption, colorOptions);
+    return determineImageType(contents, length);
 }
 
 size_t ImageDecoder::frameCount()
 {
     const size_t oldSize = m_frameBufferCache.size();
     const size_t newSize = decodeFrameCount();
     if (oldSize != newSize) {
         m_frameBufferCache.resize(newSize);
         for (size_t i = oldSize; i < newSize; ++i) {
             m_frameBufferCache[i].setPremultiplyAlpha(m_premultiplyAlpha);
@@ skipping 247 matching lines @@
 }
 
 bool ImageDecoder::hasColorProfile() const
 {
     return false;
 }
 
 #endif // USE(QCMSLIB)
 
 } // namespace blink