SkPDF: Subset Type3 (fallback) font

src/pdf/SkPDFTypes.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkData.h"
 #include "SkDeflate.h"
 #include "SkPDFTypes.h"
@@ skipping 555 matching lines @@
 
     #ifdef SK_PDF_LESS_COMPRESSION
     fCompressedData = std::move(stream);
     SkASSERT(fCompressedData && fCompressedData->hasLength());
     fDict.insertInt("Length", fCompressedData->getLength());
     #else
 
     SkASSERT(stream->hasLength());
     SkDynamicMemoryWStream compressedData;
     SkDeflateWStream deflateWStream(&compressedData);
-    SkStreamCopy(&deflateWStream, stream.get());
+    if (stream->getLength() > 0) {
+        SkStreamCopy(&deflateWStream, stream.get());
+    }
     deflateWStream.finalize();
     size_t compressedLength = compressedData.bytesWritten();
     size_t originalLength = stream->getLength();
 
     if (originalLength <= compressedLength + strlen("/Filter_/FlateDecode_")) {
         SkAssertResult(stream->rewind());
         fCompressedData = std::move(stream);
         fDict.insertInt("Length", originalLength);
         return;
     }
@@ skipping 53 matching lines @@
 
 void SkPDFImageDumpStats() {
     SkDebugf("\ntotal PDF drawImage/drawBitmap calls: %d\n"
              "total PDF jpeg images: %d\n"
              "total PDF regular images: %d\n",
              gDrawImageCalls.load(),
              gJpegImageObjects.load(),
              gRegularImageObjects.load());
 }
 #endif // SK_PDF_IMAGE_STATS