Allow passing in strings of length zero to FileWrapper::Write without closing the file.

webrtc/system_wrappers/source/file_impl.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 225 matching lines @@
     return false;
 
   // Check if it's time to stop writing.
   if (max_size_in_bytes_ > 0 &&
       (size_in_bytes_ + length) > max_size_in_bytes_) {
     FlushImpl();
     return false;
   }
 
   size_t num_bytes = fwrite(buf, 1, length, id_);
-  if (num_bytes > 0) {
-    size_in_bytes_ += num_bytes;
-    return true;
+  size_in_bytes_ += num_bytes;
+  if (num_bytes != length) {
+    CloseFileImpl();
+    return false;
   }
-
-  CloseFileImpl();
-  return false;
+  return true;
 }
 
 int FileWrapperImpl::CloseFileImpl() {
   if (id_ != NULL) {
     if (managed_file_handle_)
       fclose(id_);
     id_ = NULL;
   }
   memset(file_name_utf8_, 0, kMaxFileNameSize);
   open_ = false;
   return 0;
 }
 
 int FileWrapperImpl::FlushImpl() {
   if (id_ != NULL) {
     return fflush(id_);
   }
   return -1;
 }
 
 int FileWrapper::Rewind() {
   RTC_DCHECK(false);
   return -1;
 }
 
 }  // namespace webrtc