Fix fragmented image signature handling

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
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  *  Library General Public License for more details.
  *
  *  You should have received a copy of the GNU Library General Public License
  *  along with this library; see the file COPYING.LIB.  If not, write to
  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  *  Boston, MA 02110-1301, USA.
  *
  */
 
 #include "platform/image-decoders/ImageDecoder.h"
 
 #include "platform/PlatformInstrumentation.h"
+#include "platform/image-decoders/FastSharedBufferReader.h"
 #include "platform/image-decoders/bmp/BMPImageDecoder.h"
 #include "platform/image-decoders/gif/GIFImageDecoder.h"
 #include "platform/image-decoders/ico/ICOImageDecoder.h"
 #include "platform/image-decoders/jpeg/JPEGImageDecoder.h"
 #include "platform/image-decoders/png/PNGImageDecoder.h"
 #include "platform/image-decoders/webp/WEBPImageDecoder.h"
 #include "wtf/PtrUtil.h"
 #include <memory>
 
 namespace blink {
@@ skipping 39 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);
 }
 
+namespace {
+
+// This needs to be updated if we ever add a matches*Signature() which requires more characters.
+constexpr size_t kLongestSignatureLength = sizeof("RIFF????WEBPVP") - 1;
+
+} // anonymous ns
+
 std::unique_ptr<ImageDecoder> ImageDecoder::create(const char* contents, size_t length, AlphaOption alphaOption, GammaAndColorProfileOption colorOptions)
 {
-    const size_t longestSignatureLength = sizeof("RIFF????WEBPVP") - 1;
-    ASSERT(longestSignatureLength == 14);
-
-    if (length < longestSignatureLength)
+    if (length < kLongestSignatureLength)
         return nullptr;
 
     size_t maxDecodedBytes = Platform::current() ? Platform::current()->maxDecodedImageBytes() : noDecodedImageByteLimit;
 
     if (matchesJPEGSignature(contents))
         return wrapUnique(new JPEGImageDecoder(alphaOption, colorOptions, maxDecodedBytes));
 
     if (matchesPNGSignature(contents))
         return wrapUnique(new PNGImageDecoder(alphaOption, colorOptions, maxDecodedBytes));
 
     if (matchesGIFSignature(contents))
         return wrapUnique(new GIFImageDecoder(alphaOption, colorOptions, maxDecodedBytes));
 
     if (matchesWebPSignature(contents))
         return wrapUnique(new WEBPImageDecoder(alphaOption, colorOptions, maxDecodedBytes));
 
     if (matchesICOSignature(contents) || matchesCURSignature(contents))
         return wrapUnique(new ICOImageDecoder(alphaOption, colorOptions, maxDecodedBytes));
 
     if (matchesBMPSignature(contents))
         return wrapUnique(new BMPImageDecoder(alphaOption, colorOptions, maxDecodedBytes));
 
     return nullptr;
 }
 
 std::unique_ptr<ImageDecoder> ImageDecoder::create(const SharedBuffer& data, AlphaOption alphaOption, GammaAndColorProfileOption colorOptions)
 {
-    const char* contents;
-    const size_t length = data.getSomeData<size_t>(contents);
-    return create(contents, length, alphaOption, colorOptions);
+    RefPtr<SegmentReader> reader = SegmentReader::createFromSharedBuffer(const_cast<SharedBuffer*>(&data));
+    return create(*reader, alphaOption, colorOptions);
 }
 
 std::unique_ptr<ImageDecoder> ImageDecoder::create(const SegmentReader& data, AlphaOption alphaOption, GammaAndColorProfileOption colorOptions)
 {
-    const char* contents;
-    const size_t length = data.getSomeData(contents, 0);
-    return create(contents, length, alphaOption, colorOptions);
+    const FastSharedBufferReader fastReader(const_cast<SegmentReader*>(&data));
+    char buffer[kLongestSignatureLength];
+    const size_t len = std::min(kLongestSignatureLength, data.size());
+
+    return create(fastReader.getConsecutiveData(0, len, buffer), len,  alphaOption, colorOptions);
 }
 
 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