Get rid of leaks in SkCodec::NewFromStream.

src/codec/SkCodec_libbmp.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCodec_libbmp.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 478 matching lines @@
     return true;
 }
 
 /*
  *
  * Creates a bmp decoder
  * Reads enough of the stream to determine the image format
  *
  */
 SkCodec* SkBmpCodec::NewFromStream(SkStream* stream, bool isIco) {
+    SkAutoTDelete<SkStream> streamDeleter(stream);
     SkCodec* codec = NULL;
     if (ReadHeader(stream, isIco, &codec)) {

[mtklein, 2015/04/03 13:13:05]

Might be less error prone to have ReadHeader take ownership too:

if (ReadHeader(stream.detach(), isIco, &codec)) {
  return codec;
}

[scroggo, 2015/04/03 13:59:53]

Yeah, I was not sure the best way to handle this. The problem with that approach
is that we call ReadHeader in two places:

This time, it make sense for ReadHeader to take ownership and pass to the codec
if it creates one.

The other time, after a rewind, we already have a codec, and it already owns the
stream. In this case we pass NULL for codec.

We could make ReadHeader behave differently with regards to taking ownership
depending on whether a codec pointer is passed in, but that seems ugly to me.
(Maybe no worse than this decision though?)

+        // codec has taken ownership of stream, so we do not need to
+        // delete it.
+        SkASSERT(codec);
+        streamDeleter.detach();
         return codec;
     }
     return NULL;
 }
 
 /*
  *
  * Creates an instance of the decoder
  * Called only by NewFromStream
  *
@@ skipping 615 matching lines @@
                 uint32_t alphaBit =
                         (srcBuffer.get()[quotient] >> shift) & 0x1;
                 dstRow[x] &= alphaBit - 1;
             }
         }
     }
 
     // Finished decoding the entire image
     return kSuccess;
 }