Function cupsBackChannelWrite

cups/backchannel.c:95–165

 */

ssize_t					/* O - Bytes written or -1 on error */
cupsBackChannelWrite(
    const char *buffer,			/* I - Buffer to write */
    size_t     bytes,			/* I - Bytes to write */
    double     timeout)			/* I - Timeout in seconds, typically 1.0 */
{
  fd_set	output;			/* Output set */
  struct timeval tval;			/* Timeout value */
  int		status;			/* Select status */
  ssize_t	count;			/* Current bytes */
  size_t	total;			/* Total bytes */


 /*
  * Write all bytes...
  */

  total = 0;

  while (total < bytes)
  {
   /*
    * Wait for write-ready...
    */

    do
    {
      cups_setup(&output, &tval, timeout);

      if (timeout < 0.0)
	status = select(4, NULL, &output, NULL, NULL);
      else
	status = select(4, NULL, &output, NULL, &tval);
    }
    while (status < 0 && errno != EINTR && errno != EAGAIN);

    if (status <= 0)
      return (-1);			/* Timeout! */

   /*
    * Write bytes to the pipe...
    */

#ifdef _WIN32
    count = (ssize_t)_write(3, buffer, (unsigned)(bytes - total));
#else
    count = write(3, buffer, bytes - total);
#endif /* _WIN32 */

    if (count < 0)
    {
     /*
      * Write error - abort on fatal errors...
      */

      if (errno != EINTR && errno != EAGAIN)
        return (-1);
    }