Logging errors

LogErrno.cc

void LogError(const char *fmt, ...) {
  va_list vlist;
  va_start(vlist, fmt);

  const size_t kLogMessageLength = 128;
  char log_message[kLogMessageLength];
  vsnprintf(log_message, kLogMessageLength, fmt, vlist);

  LogError(log_message);
  va_end(vlist);
}

/* Log the error getting from errno */
void LogErrno(const char *msg) {
  char buf[kBufferSize];
  strerror_r(errno, buf, kBufferSize);
  LogError(stderr, "%s: %s\n", msg, buf);
}