Fix potential bug in FastSharedBufferReader::getConsecutiveData

Source/platform/image-decoders/FastSharedBufferReader.cpp

Index: Source/platform/image-decoders/FastSharedBufferReader.cpp
diff --git a/Source/platform/image-decoders/FastSharedBufferReader.cpp b/Source/platform/image-decoders/FastSharedBufferReader.cpp
index 4475960fdcb4a12dab70112a482d779630b558e4..e02a70551c706556f5f4b1787cc1f8eae29248bc 100644
--- a/Source/platform/image-decoders/FastSharedBufferReader.cpp
+++ b/Source/platform/image-decoders/FastSharedBufferReader.cpp
@@ -56,17 +56,25 @@ const char* FastSharedBufferReader::getConsecutiveData(size_t dataPosition, size
     if (length <= m_segmentLength)
         return m_segment;
 
-    for (char* tempBuffer = buffer; length;) {
+    char* dest = buffer;

[Peter Kasting, 2015/03/20 20:29:33]

Nit: Convert the while to a for so you can move this declaration inside it
("declare variables in the narrowest possible scope").

+    while (true) {
         size_t copy = std::min(length, m_segmentLength);
-        memcpy(tempBuffer, m_segment, copy);
+        memcpy(dest, m_segment, copy);
         m_dataPosition += copy;

[kbalazs, 2015/03/25 19:38:10]

I also introduced an error. m_dataPosition should not be changed if we are not
continue reading. I will make some refactor too make this code easier to read.

         length -= copy;
-        tempBuffer += copy;
+        if (!length) {
+            // Done.
+            return buffer;
+        }
 
+        // Continue reading the next segment.
+        dest += copy;
         m_segmentLength = m_data->getSomeData(m_segment, m_dataPosition);
         ASSERT(m_segmentLength);
     }
-    return buffer;
+
+    ASSERT_NOT_REACHED();

[Peter Kasting, 2015/03/20 01:10:42]

I think these two lines will trigger MSVC warning C4702, and you should remove
them.

[kbalazs, 2015/03/20 20:20:42]

Acknowledged.

+    return 0;
 }
 
 size_t FastSharedBufferReader::getSomeData(const char*& someData, size_t dataPosition)