Check the return value of fwrite....

src/log.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 362 matching lines @@
       Append("\\\\");
     } else {
       Append("%lc", c);
     }
   }
 }
 
 // Write the log message to the log file currently opened.
 void LogMessageBuilder::WriteToLogFile() {
   ASSERT(pos_ <= Logger::kMessageBufferSize);
-  fwrite(Logger::message_buffer_, 1, pos_, Logger::logfile_);
+  size_t rv = fwrite(Logger::message_buffer_, 1, pos_, Logger::logfile_);
+  ASSERT(rv == static_cast<size_t>(pos_));
 }
 #endif
 
 
 //
 // Logger class implementation.
 //
 Ticker* Logger::ticker_ = NULL;
 char* Logger::message_buffer_ = NULL;
 FILE* Logger::logfile_ = NULL;
@@ skipping 736 matching lines @@
   if (FLAG_log_state_changes) {
     LOG(UncheckedStringEvent("Leaving", StateToString(state_)));
     if (previous_) {
       LOG(UncheckedStringEvent("To", StateToString(previous_->state_)));
     }
   }
 }
 #endif
 
 } }  // namespace v8::internal