Add debug-printing to file, and remove from test.

runtime/bin/file.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/file.h"
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
 #include "bin/io_buffer.h"
 #include "bin/thread.h"
@@ skipping 238 matching lines @@
   // The buffer object passed in has to be an Int8List or Uint8List object.
   // Acquire a direct pointer to the data area of the buffer object.
   Dart_TypedData_Type type;
   intptr_t length = end - start;
   intptr_t buffer_len = 0;
   void* buffer = NULL;
   Dart_Handle result =
       Dart_TypedDataAcquireData(buffer_obj, &type, &buffer, &buffer_len);
   if (Dart_IsError(result)) Dart_PropagateError(result);
 
+#ifdef DEBUG
+  // TODO(ajohnsen): Remove once issue 17602 is fixed.
+  bool print_debug = true;
+  for (int i = 0; i < length; i++) {
+    if (reinterpret_cast<uint8_t*>(buffer)[i] != 0xf3) {
+      print_debug = false;
+      break;
+    }
+  }
+  if (print_debug) {
+    fprintf(stderr, "WARNING: Data is purely 0x3f in File_WriteFrom\n");
+    fflush(stderr);
+  }
+#endif
+
   ASSERT(type == Dart_TypedData_kUint8 || type == Dart_TypedData_kInt8);
   ASSERT(end <= buffer_len);
   ASSERT(buffer != NULL);
 
   // Write the data out into the file.
-  int64_t bytes_written = file->Write(reinterpret_cast<void*>(buffer), length);
+  int64_t bytes_written = file->Write(buffer, length);
   // Release the direct pointer acquired above.
   result = Dart_TypedDataReleaseData(buffer_obj);
   if (Dart_IsError(result)) Dart_PropagateError(result);
 
   if (bytes_written != length) {
     Dart_Handle err = DartUtils::NewDartOSError();
     if (Dart_IsError(err)) Dart_PropagateError(err);
     Dart_SetReturnValue(args, err);
   }
 }
@@ skipping 910 matching lines @@
     CObjectArray* wrapper = new CObjectArray(CObject::NewArray(2));
     wrapper->SetAt(0, new CObjectInt32(CObject::NewInt32(CObject::kSuccess)));
     wrapper->SetAt(1, result);
     return wrapper;
   }
   return CObject::IllegalArgumentError();
 }
 
 }  // namespace bin
 }  // namespace dart