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/RuntimeEnabledFeatures.h"
 #include "platform/graphics/BitmapImageMetrics.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 64 matching lines @@
     case SniffResult::BMP:
         return wrapUnique(new BMPImageDecoder(alphaOption, colorOptions, maxDecodedBytes));
     case SniffResult::InsufficientData:
     case SniffResult::Invalid:
         return nullptr;
     }
     NOTREACHED();
     return nullptr;
 }
 
+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
+
 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)
+    if (length < kLongestSignatureLength)
         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 determineImageType(contents, length);
+    // TODO(fmalita): refactor the method signature to avoid casting.
+    RefPtr<SegmentReader> reader = SegmentReader::createFromSharedBuffer(const_cast<SharedBuffer*>(&data));
+
+    return determineImageType(*reader);
 }
 
 ImageDecoder::SniffResult ImageDecoder::determineImageType(const SegmentReader& data)
 {
-    const char* contents;
-    const size_t length = data.getSomeData(contents, 0);
-    return determineImageType(contents, length);
+    // TODO(fmalita): refactor the method signature to avoid casting.
+    const FastSharedBufferReader fastReader(const_cast<SegmentReader*>(&data));
+    char buffer[kLongestSignatureLength];
+    const size_t len = std::min(kLongestSignatureLength, data.size());
+
+    return determineImageType(fastReader.getConsecutiveData(0, len, buffer), len);
 }
 
 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 251 matching lines @@
         return;
 
     qcms_data_type dataFormat = hasAlpha ? QCMS_DATA_RGBA_8 : QCMS_DATA_RGB_8;
 
     // FIXME: Don't force perceptual intent if the image profile contains an intent.
     m_sourceToOutputDeviceColorTransform.reset(qcms_transform_create(inputProfile.get(), dataFormat, gTargetColorProfile, QCMS_DATA_RGBA_8, QCMS_INTENT_PERCEPTUAL));
 #endif // USE(QCMSLIB)
 }
 
 } // namespace blink