Do not consolidate data in BMPImageDecoder

Source/platform/image-decoders/bmp/BMPImageDecoder.cpp

 /*
  * Copyright (c) 2008, 2009, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 13 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "platform/image-decoders/bmp/BMPImageDecoder.h"
 
+#include "platform/image-decoders/FastSharedBufferReader.h"
 #include "wtf/PassOwnPtr.h"
 
 namespace blink {
 
 // Number of bits in .BMP used to store the file header (doesn't match
 // "sizeof(BMPImageDecoder::BitmapFileHeader)" since we omit some fields and
 // don't pack).
 static const size_t sizeOfFileHeader = 14;
 
 BMPImageDecoder::BMPImageDecoder(AlphaOption alphaOption, GammaAndColorProfileOption colorOptions, size_t maxDecodedBytes)
@@ skipping 49 matching lines @@
 
     return m_reader->decodeBMP(onlySize);
 }
 
 bool BMPImageDecoder::processFileHeader(size_t& imgDataOffset)
 {
     // Read file header.
     ASSERT(!m_decodedOffset);
     if (m_data->size() < sizeOfFileHeader)
         return false;
-    const uint16_t fileType = (m_data->data()[0] << 8) | static_cast<uint8_t>(m_data->data()[1]);
-    imgDataOffset = readUint32(10);
+
+    char buffer[sizeOfFileHeader];
+    FastSharedBufferReader fastReader(m_data);
+    const char* fileHeader = fastReader.getConsecutiveData(0, sizeOfFileHeader, buffer);
+    const uint16_t fileType = (fileHeader[0] << 8) | static_cast<uint8_t>(fileHeader[1]);
+    imgDataOffset = BMPImageReader::readUint32(&fileHeader[10]);
     m_decodedOffset = sizeOfFileHeader;
 
     // See if this is a bitmap filetype we understand.
     enum {
         BMAP = 0x424D,  // "BM"
         // The following additional OS/2 2.x header values (see
         // http://www.fileformat.info/format/os2bmp/egff.htm ) aren't widely
         // decoded, and are unlikely to be in much use.
         /*
         ICON = 0x4943,  // "IC"
         POINTER = 0x5054,  // "PT"
         COLORICON = 0x4349,  // "CI"
         COLORPOINTER = 0x4350,  // "CP"
         BITMAPARRAY = 0x4241,  // "BA"
         */
     };
     return (fileType == BMAP) || setFailed();
 }
 
 } // namespace blink