Add an assert that we still have a buffer to readFromBuffer().

src/utils/SkFrontBufferedStream.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkFrontBufferedStream.h"
 #include "SkStream.h"
 #include "SkTemplates.h"
@@ skipping 101 matching lines @@
     // within the buffered data.
     fOffset += bytesToCopy;
     SkASSERT(fOffset <= fBufferedSoFar);
 
     return bytesToCopy;
 }
 
 size_t FrontBufferedStream::bufferAndWriteTo(char* dst, size_t size) {
     SkASSERT(size > 0);
     SkASSERT(fOffset >= fBufferedSoFar);
+    SkASSERT(fBuffer);
     // Data needs to be buffered. Buffer up to the lesser of the size requested
     // and the remainder of the max buffer size.
     const size_t bytesToBuffer = SkTMin(size, fBufferSize - fBufferedSoFar);
     char* buffer = fBuffer + fOffset;
     const size_t buffered = fStream->read(buffer, bytesToBuffer);
 
     fBufferedSoFar += buffered;
     fOffset = fBufferedSoFar;
     SkASSERT(fBufferedSoFar <= fBufferSize);
 
     // Copy the buffer to the destination buffer and update the amount read.
     if (dst != NULL) {
         memcpy(dst, buffer, buffered);
     }
 
     return buffered;
 }
 
 size_t FrontBufferedStream::readDirectlyFromStream(char* dst, size_t size) {
     SkASSERT(size > 0);
     // If we get here, we have buffered all that can be buffered.
     SkASSERT(fBufferSize == fBufferedSoFar && fOffset >= fBufferSize);
 
     const size_t bytesReadDirectly = fStream->read(dst, size);
     fOffset += bytesReadDirectly;
 
     // If we have read past the end of the buffer, rewinding is no longer
     // supported, so we can go ahead and free the memory.
     if (bytesReadDirectly > 0) {
-        fBuffer.reset(0);
+        sk_free(fBuffer.detach());
     }
 
     return bytesReadDirectly;
 }
 
 size_t FrontBufferedStream::read(void* voidDst, size_t size) {
     // Cast voidDst to a char* for easy addition.
     char* dst = reinterpret_cast<char*>(voidDst);
     SkDEBUGCODE(const size_t totalSize = size;)
     const size_t start = fOffset;
@@ skipping 26 matching lines @@
     }
 
     if (size > 0 && !fStream->isAtEnd()) {
         SkDEBUGCODE(const size_t bytesReadDirectly =) this->readDirectlyFromStream(dst, size);
         SkDEBUGCODE(size -= bytesReadDirectly;)
         SkASSERT(size + (fOffset - start) == totalSize);
     }
 
     return fOffset - start;
 }