[thirdparty/cups.git] / backend / runloop.c

/*
 * Common run loop APIs for CUPS backends.
 *
 * Copyright 2007-2014 by Apple Inc.
 * Copyright 2006-2007 by Easy Software Products, all rights reserved.
 *
 * These coded instructions, statements, and computer programs are the
 * property of Apple Inc. and are protected by Federal copyright
 * law.  Distribution and use rights are outlined in the file "LICENSE.txt"
 * "LICENSE" which should have been included with this file.  If this
 * file is missing or damaged, see the license at "http://www.cups.org/".
 */

/*
 * Include necessary headers.
 */

#include "backend-private.h"
#include <limits.h>
#include <sys/select.h>


/*
 * 'backendDrainOutput()' - Drain pending print data to the device.
 */

int					/* O - 0 on success, -1 on error */
backendDrainOutput(int print_fd,	/* I - Print file descriptor */
                   int device_fd)	/* I - Device file descriptor */
{
  int		nfds;			/* Maximum file descriptor value + 1 */
  fd_set	input;			/* Input set for reading */
  ssize_t	print_bytes,		/* Print bytes read */
		bytes;			/* Bytes written */
  char		print_buffer[8192],	/* Print data buffer */
		*print_ptr;		/* Pointer into print data buffer */
  struct timeval timeout;		/* Timeout for read... */


  fprintf(stderr, "DEBUG: backendDrainOutput(print_fd=%d, device_fd=%d)\n",
          print_fd, device_fd);

 /*
  * Figure out the maximum file descriptor value to use with select()...
  */

  nfds = (print_fd > device_fd ? print_fd : device_fd) + 1;

 /*
  * Now loop until we are out of data from print_fd...
  */

  for (;;)
  {
   /*
    * Use select() to determine whether we have data to copy around...
    */

    FD_ZERO(&input);
    FD_SET(print_fd, &input);

    timeout.tv_sec  = 0;
    timeout.tv_usec = 0;

    if (select(nfds, &input, NULL, NULL, &timeout) < 0)
      return (-1);

    if (!FD_ISSET(print_fd, &input))
      return (0);

    if ((print_bytes = read(print_fd, print_buffer,
			    sizeof(print_buffer))) < 0)
    {
     /*
      * Read error - bail if we don't see EAGAIN or EINTR...
      */

      if (errno != EAGAIN && errno != EINTR)
      {
	fprintf(stderr, "DEBUG: Read failed: %s\n", strerror(errno));
	_cupsLangPrintFilter(stderr, "ERROR", _("Unable to read print data."));
	return (-1);
      }

      print_bytes = 0;
    }
    else if (print_bytes == 0)
    {
     /*
      * End of file, return...
      */

      return (0);
    }

    fprintf(stderr, "DEBUG: Read %d bytes of print data...\n",
	    (int)print_bytes);

    for (print_ptr = print_buffer; print_bytes > 0;)
    {
      if ((bytes = write(device_fd, print_ptr, (size_t)print_bytes)) < 0)
      {
       /*
        * Write error - bail if we don't see an error we can retry...
	*/

        if (errno != ENOSPC && errno != ENXIO && errno != EAGAIN &&
	    errno != EINTR && errno != ENOTTY)
	{
	  _cupsLangPrintError("ERROR", _("Unable to write print data"));
	  return (-1);
	}
      }
      else
      {
        fprintf(stderr, "DEBUG: Wrote %d bytes of print data...\n", (int)bytes);

        print_bytes -= bytes;
	print_ptr   += bytes;
      }
    }
  }
}


/*
 * 'backendRunLoop()' - Read and write print and back-channel data.
 */

ssize_t					/* O - Total bytes on success, -1 on error */
backendRunLoop(
    int          print_fd,		/* I - Print file descriptor */
    int          device_fd,		/* I - Device file descriptor */
    int          snmp_fd,		/* I - SNMP socket or -1 if none */
    http_addr_t  *addr,			/* I - Address of device */
    int          use_bc,		/* I - Use back-channel? */
    int          update_state,		/* I - Update printer-state-reasons? */
    _cups_sccb_t side_cb)		/* I - Side-channel callback */
{
  int		nfds;			/* Maximum file descriptor value + 1 */
  fd_set	input,			/* Input set for reading */
		output;			/* Output set for writing */
  ssize_t	print_bytes,		/* Print bytes read */
		bc_bytes,		/* Backchannel bytes read */
		total_bytes,		/* Total bytes written */
		bytes;			/* Bytes written */
  int		paperout;		/* "Paper out" status */
  int		offline;		/* "Off-line" status */
  char		print_buffer[8192],	/* Print data buffer */
		*print_ptr,		/* Pointer into print data buffer */
		bc_buffer[1024];	/* Back-channel data buffer */
  struct timeval timeout;		/* Timeout for select() */
  time_t	curtime,		/* Current time */
		snmp_update = 0;
#if defined(HAVE_SIGACTION) && !defined(HAVE_SIGSET)
  struct sigaction action;		/* Actions for POSIX signals */
#endif /* HAVE_SIGACTION && !HAVE_SIGSET */


  fprintf(stderr,
          "DEBUG: backendRunLoop(print_fd=%d, device_fd=%d, snmp_fd=%d, "
	  "addr=%p, use_bc=%d, side_cb=%p)\n",
          print_fd, device_fd, snmp_fd, addr, use_bc, side_cb);

 /*
  * If we are printing data from a print driver on stdin, ignore SIGTERM
  * so that the driver can finish out any page data, e.g. to eject the
  * current page.  We only do this for stdin printing as otherwise there
  * is no way to cancel a raw print job...
  */

  if (!print_fd)
  {
#ifdef HAVE_SIGSET /* Use System V signals over POSIX to avoid bugs */
    sigset(SIGTERM, SIG_IGN);
#elif defined(HAVE_SIGACTION)
    memset(&action, 0, sizeof(action));

    sigemptyset(&action.sa_mask);
    action.sa_handler = SIG_IGN;
    sigaction(SIGTERM, &action, NULL);
#else
    signal(SIGTERM, SIG_IGN);
#endif /* HAVE_SIGSET */
  }
  else if (print_fd < 0)
  {
   /*
    * Copy print data from stdin, but don't mess with the signal handlers...
    */

    print_fd = 0;
  }

 /*
  * Figure out the maximum file descriptor value to use with select()...
  */

  nfds = (print_fd > device_fd ? print_fd : device_fd) + 1;

 /*
  * Now loop until we are out of data from print_fd...
  */

  for (print_bytes = 0, print_ptr = print_buffer, offline = -1,
           paperout = -1, total_bytes = 0;;)
  {
   /*
    * Use select() to determine whether we have data to copy around...
    */

    FD_ZERO(&input);
    if (!print_bytes)
      FD_SET(print_fd, &input);
    if (use_bc)
      FD_SET(device_fd, &input);
    if (!print_bytes && side_cb)
      FD_SET(CUPS_SC_FD, &input);

    FD_ZERO(&output);
    if (print_bytes || (!use_bc && !side_cb))
      FD_SET(device_fd, &output);

    if (use_bc || side_cb)
    {
      timeout.tv_sec  = 5;
      timeout.tv_usec = 0;

      if (select(nfds, &input, &output, NULL, &timeout) < 0)
      {
       /*
	* Pause printing to clear any pending errors...
	*/

	if (errno == ENXIO && offline != 1 && update_state)
	{
	  fputs("STATE: +offline-report\n", stderr);
	  _cupsLangPrintFilter(stderr, "INFO",
	                       _("The printer is not connected."));
	  offline = 1;
	}
	else if (errno == EINTR && total_bytes == 0)
	{
	  fputs("DEBUG: Received an interrupt before any bytes were "
	        "written, aborting.\n", stderr);
          return (0);
	}

	sleep(1);
	continue;
      }
    }

   /*
    * Check if we have a side-channel request ready...
    */

    if (side_cb && FD_ISSET(CUPS_SC_FD, &input))
    {
     /*
      * Do the side-channel request, then start back over in the select
      * loop since it may have read from print_fd...
      */

      if ((*side_cb)(print_fd, device_fd, snmp_fd, addr, use_bc))
        side_cb = NULL;
      continue;
    }

   /*
    * Check if we have back-channel data ready...
    */

    if (FD_ISSET(device_fd, &input))
    {
      if ((bc_bytes = read(device_fd, bc_buffer, sizeof(bc_buffer))) > 0)
      {
	fprintf(stderr,
	        "DEBUG: Received " CUPS_LLFMT " bytes of back-channel data\n",
	        CUPS_LLCAST bc_bytes);
        cupsBackChannelWrite(bc_buffer, (size_t)bc_bytes, 1.0);
      }
      else if (bc_bytes < 0 && errno != EAGAIN && errno != EINTR)
      {
        fprintf(stderr, "DEBUG: Error reading back-channel data: %s\n",
	        strerror(errno));
	use_bc = 0;
      }
      else if (bc_bytes == 0)
        use_bc = 0;
    }

   /*
    * Check if we have print data ready...
    */

    if (FD_ISSET(print_fd, &input))
    {
      if ((print_bytes = read(print_fd, print_buffer,
                              sizeof(print_buffer))) < 0)
      {
       /*
        * Read error - bail if we don't see EAGAIN or EINTR...
	*/

	if (errno != EAGAIN && errno != EINTR)
	{
	  fprintf(stderr, "DEBUG: Read failed: %s\n", strerror(errno));
	  _cupsLangPrintFilter(stderr, "ERROR",
	                       _("Unable to read print data."));
	  return (-1);
	}

        print_bytes = 0;
      }
      else if (print_bytes == 0)
      {
       /*
        * End of file, break out of the loop...
	*/

        break;
      }

      print_ptr = print_buffer;

      fprintf(stderr, "DEBUG: Read %d bytes of print data...\n",
              (int)print_bytes);
    }

   /*
    * Check if the device is ready to receive data and we have data to
    * send...
    */

    if (print_bytes && FD_ISSET(device_fd, &output))
    {
      if ((bytes = write(device_fd, print_ptr, (size_t)print_bytes)) < 0)
      {
       /*
        * Write error - bail if we don't see an error we can retry...
	*/

        if (errno == ENOSPC)
	{
	  if (paperout != 1 && update_state)
	  {
	    fputs("STATE: +media-empty-warning\n", stderr);
	    fputs("DEBUG: Out of paper\n", stderr);
	    paperout = 1;
	  }
        }
	else if (errno == ENXIO)
	{
	  if (offline != 1 && update_state)
	  {
	    fputs("STATE: +offline-report\n", stderr);
	    _cupsLangPrintFilter(stderr, "INFO",
	                         _("The printer is not connected."));
	    offline = 1;
	  }
	}
	else if (errno != EAGAIN && errno != EINTR && errno != ENOTTY)
	{
	  _cupsLangPrintError("ERROR", _("Unable to write print data"));
	  return (-1);
	}
      }
      else
      {
        if (paperout && update_state)
	{
	  fputs("STATE: -media-empty-warning\n", stderr);
	  paperout = 0;
	}

	if (offline && update_state)
	{
	  fputs("STATE: -offline-report\n", stderr);
	  _cupsLangPrintFilter(stderr, "INFO",
	                       _("The printer is now connected."));
	  offline = 0;
	}

        fprintf(stderr, "DEBUG: Wrote %d bytes of print data...\n", (int)bytes);

        print_bytes -= bytes;
	print_ptr   += bytes;
	total_bytes += bytes;
      }
    }

   /*
    * Do SNMP updates periodically...
    */

    if (snmp_fd >= 0 && time(&curtime) >= snmp_update)
    {
      if (backendSNMPSupplies(snmp_fd, addr, NULL, NULL))
        snmp_update = INT_MAX;
      else
        snmp_update = curtime + 5;
    }
  }

 /*
  * Return with success...
  */

  return (total_bytes);
}


/*
 * 'backendWaitLoop()' - Wait for input from stdin while handling side-channel
 *                       queries.
 */

int					/* O - 1 if data is ready, 0 if not */
backendWaitLoop(
    int          snmp_fd,		/* I - SNMP socket or -1 if none */
    http_addr_t  *addr,			/* I - Address of device */
    int          use_bc,		/* I - Use back-channel? */
    _cups_sccb_t side_cb)		/* I - Side-channel callback */
{
  int			nfds;		/* Number of file descriptors */
  fd_set		input;		/* Input set for reading */
  time_t		curtime = 0,	/* Current time */
			snmp_update = 0;/* Last SNMP status update */
  struct timeval	timeout;	/* Timeout for select() */


  fprintf(stderr, "DEBUG: backendWaitLoop(snmp_fd=%d, addr=%p, side_cb=%p)\n",
	  snmp_fd, addr, side_cb);

 /*
  * Now loop until we receive data from stdin...
  */

  if (snmp_fd >= 0)
    snmp_update = time(NULL) + 5;

  for (;;)
  {
   /*
    * Use select() to determine whether we have data to copy around...
    */

    FD_ZERO(&input);
    FD_SET(0, &input);
    if (side_cb)
      FD_SET(CUPS_SC_FD, &input);

    if (snmp_fd >= 0)
    {
      curtime         = time(NULL);
      timeout.tv_sec  = curtime >= snmp_update ? 0 : snmp_update - curtime;
      timeout.tv_usec = 0;

      nfds = select(CUPS_SC_FD + 1, &input, NULL, NULL, &timeout);
    }
    else
      nfds = select(CUPS_SC_FD + 1, &input, NULL, NULL, NULL);

    if (nfds < 0)
    {
     /*
      * Pause printing to clear any pending errors...
      */

      if (errno == EINTR)
      {
	fputs("DEBUG: Received an interrupt before any bytes were "
	      "written, aborting.\n", stderr);
	return (0);
      }

      sleep(1);
      continue;
    }

   /*
    * Check for input on stdin...
    */

    if (FD_ISSET(0, &input))
      break;

   /*
    * Check if we have a side-channel request ready...
    */

    if (side_cb && FD_ISSET(CUPS_SC_FD, &input))
    {
     /*
      * Do the side-channel request, then start back over in the select
      * loop since it may have read from print_fd...
      */

      if ((*side_cb)(0, -1, snmp_fd, addr, use_bc))
        side_cb = NULL;
      continue;
    }

   /*
    * Do SNMP updates periodically...
    */

    if (snmp_fd >= 0 && curtime >= snmp_update)
    {
      if (backendSNMPSupplies(snmp_fd, addr, NULL, NULL))
        snmp_fd = -1;
      else
        snmp_update = curtime + 5;
    }
  }

 /*
  * Return with success...
  */

  return (1);
}
Commit	Line	Data
ed486911	1	/*
5a1d7a17	2	* Common run loop APIs for CUPS backends.
ed486911	3	*
7e86f2f6	4	* Copyright 2007-2014 by Apple Inc.
5a1d7a17	5	* Copyright 2006-2007 by Easy Software Products, all rights reserved.
ed486911	6	*
5a1d7a17 MS	7	* These coded instructions, statements, and computer programs are the
	8	* property of Apple Inc. and are protected by Federal copyright
	9	* law. Distribution and use rights are outlined in the file "LICENSE.txt"
	10	* "LICENSE" which should have been included with this file. If this
	11	* file is missing or damaged, see the license at "http://www.cups.org/".
ed486911	12	*/
	13
	14	/*
	15	* Include necessary headers.
	16	*/
	17
	18	#include "backend-private.h"
568fa3fa	19	#include <limits.h>
5a1d7a17	20	#include <sys/select.h>
ed486911	21
ed486911	22
09a101d6	23	/*
	24	* 'backendDrainOutput()' - Drain pending print data to the device.
	25	*/
	26
	27	int /* O - 0 on success, -1 on error */
	28	backendDrainOutput(int print_fd, /* I - Print file descriptor */
	29	int device_fd) /* I - Device file descriptor */
	30	{
	31	int nfds; /* Maximum file descriptor value + 1 */
	32	fd_set input; /* Input set for reading */
	33	ssize_t print_bytes, /* Print bytes read */
	34	bytes; /* Bytes written */
	35	char print_buffer[8192], /* Print data buffer */
	36	print_ptr; / Pointer into print data buffer */
	37	struct timeval timeout; /* Timeout for read... */
	38
	39
	40	fprintf(stderr, "DEBUG: backendDrainOutput(print_fd=%d, device_fd=%d)\n",
	41	print_fd, device_fd);
	42
	43	/*
	44	* Figure out the maximum file descriptor value to use with select()...
	45	*/
	46
	47	nfds = (print_fd > device_fd ? print_fd : device_fd) + 1;
	48
	49	/*
	50	* Now loop until we are out of data from print_fd...
	51	*/
	52
	53	for (;;)
	54	{
	55	/*
	56	* Use select() to determine whether we have data to copy around...
	57	*/
	58
	59	FD_ZERO(&input);
	60	FD_SET(print_fd, &input);
	61
	62	timeout.tv_sec = 0;
	63	timeout.tv_usec = 0;
	64
	65	if (select(nfds, &input, NULL, NULL, &timeout) < 0)
	66	return (-1);
	67
	68	if (!FD_ISSET(print_fd, &input))
	69	return (0);
	70
	71	if ((print_bytes = read(print_fd, print_buffer,
	72	sizeof(print_buffer))) < 0)
	73	{
	74	/*
	75	* Read error - bail if we don't see EAGAIN or EINTR...
	76	*/
	77
0b1399a2	78	if (errno != EAGAIN && errno != EINTR)
09a101d6	79	{
f3c17241 MS	80	fprintf(stderr, "DEBUG: Read failed: %s\n", strerror(errno));
f3c17241 MS	81	_cupsLangPrintFilter(stderr, "ERROR", _("Unable to read print data."));
09a101d6	82	return (-1);
	83	}
	84
	85	print_bytes = 0;
	86	}
	87	else if (print_bytes == 0)
	88	{
	89	/*
	90	* End of file, return...
	91	*/
	92
	93	return (0);
	94	}
	95
	96	fprintf(stderr, "DEBUG: Read %d bytes of print data...\n",
	97	(int)print_bytes);
	98
	99	for (print_ptr = print_buffer; print_bytes > 0;)
	100	{
7e86f2f6	101	if ((bytes = write(device_fd, print_ptr, (size_t)print_bytes)) < 0)
09a101d6	102	{
	103	/*
	104	* Write error - bail if we don't see an error we can retry...
	105	*/
	106
	107	if (errno != ENOSPC && errno != ENXIO && errno != EAGAIN &&
	108	errno != EINTR && errno != ENOTTY)
	109	{
0837b7e8	110	_cupsLangPrintError("ERROR", _("Unable to write print data"));
09a101d6	111	return (-1);
	112	}
	113	}
	114	else
	115	{
	116	fprintf(stderr, "DEBUG: Wrote %d bytes of print data...\n", (int)bytes);
	117
	118	print_bytes -= bytes;
	119	print_ptr += bytes;
	120	}
	121	}
	122	}
	123	}
	124
	125
ed486911	126	/*
	127	* 'backendRunLoop()' - Read and write print and back-channel data.
	128	*/
	129
	130	ssize_t /* O - Total bytes on success, -1 on error */
f7deaa1a	131	backendRunLoop(
c8fef167 MS	132	int print_fd, /* I - Print file descriptor */
	133	int device_fd, /* I - Device file descriptor */
	134	int snmp_fd, /* I - SNMP socket or -1 if none */
	135	http_addr_t addr, / I - Address of device */
	136	int use_bc, /* I - Use back-channel? */
	137	int update_state, /* I - Update printer-state-reasons? */
	138	_cups_sccb_t side_cb) /* I - Side-channel callback */
ed486911	139	{
	140	int nfds; /* Maximum file descriptor value + 1 */
	141	fd_set input, /* Input set for reading */
	142	output; /* Output set for writing */
	143	ssize_t print_bytes, /* Print bytes read */
	144	bc_bytes, /* Backchannel bytes read */
	145	total_bytes, /* Total bytes written */
	146	bytes; /* Bytes written */
	147	int paperout; /* "Paper out" status */
8ca02f3c	148	int offline; /* "Off-line" status */
ed486911	149	char print_buffer[8192], /* Print data buffer */
	150	print_ptr, / Pointer into print data buffer */
	151	bc_buffer[1024]; /* Back-channel data buffer */
568fa3fa MS	152	struct timeval timeout; /* Timeout for select() */
	153	time_t curtime, /* Current time */
	154	snmp_update = 0;
ed486911	155	#if defined(HAVE_SIGACTION) && !defined(HAVE_SIGSET)
	156	struct sigaction action; /* Actions for POSIX signals */
	157	#endif /* HAVE_SIGACTION && !HAVE_SIGSET */
	158
	159
c0e1af83	160	fprintf(stderr,
568fa3fa MS	161	"DEBUG: backendRunLoop(print_fd=%d, device_fd=%d, snmp_fd=%d, "
	162	"addr=%p, use_bc=%d, side_cb=%p)\n",
	163	print_fd, device_fd, snmp_fd, addr, use_bc, side_cb);
8ca02f3c	164
ed486911	165	/*
	166	* If we are printing data from a print driver on stdin, ignore SIGTERM
	167	* so that the driver can finish out any page data, e.g. to eject the
	168	* current page. We only do this for stdin printing as otherwise there
	169	* is no way to cancel a raw print job...
	170	*/
	171
	172	if (!print_fd)
	173	{
	174	#ifdef HAVE_SIGSET /* Use System V signals over POSIX to avoid bugs */
	175	sigset(SIGTERM, SIG_IGN);
	176	#elif defined(HAVE_SIGACTION)
	177	memset(&action, 0, sizeof(action));
	178
	179	sigemptyset(&action.sa_mask);
	180	action.sa_handler = SIG_IGN;
	181	sigaction(SIGTERM, &action, NULL);
	182	#else
	183	signal(SIGTERM, SIG_IGN);
	184	#endif /* HAVE_SIGSET */
	185	}
4e6f60f0 MS	186	else if (print_fd < 0)
	187	{
	188	/*
	189	* Copy print data from stdin, but don't mess with the signal handlers...
	190	*/
	191
	192	print_fd = 0;
	193	}
ed486911	194
	195	/*
	196	* Figure out the maximum file descriptor value to use with select()...
	197	*/
	198
	199	nfds = (print_fd > device_fd ? print_fd : device_fd) + 1;
	200
	201	/*
	202	* Now loop until we are out of data from print_fd...
	203	*/
	204
b94498cf	205	for (print_bytes = 0, print_ptr = print_buffer, offline = -1,
b94498cf	206	paperout = -1, total_bytes = 0;;)
ed486911	207	{
	208	/*
	209	* Use select() to determine whether we have data to copy around...
	210	*/
	211
	212	FD_ZERO(&input);
	213	if (!print_bytes)
	214	FD_SET(print_fd, &input);
	215	if (use_bc)
	216	FD_SET(device_fd, &input);
dd1abb6b	217	if (!print_bytes && side_cb)
f7deaa1a	218	FD_SET(CUPS_SC_FD, &input);
ed486911	219
ed486911	220	FD_ZERO(&output);
91c84a35	221	if (print_bytes \|\| (!use_bc && !side_cb))
ed486911	222	FD_SET(device_fd, &output);
ed486911	223
f7deaa1a	224	if (use_bc \|\| side_cb)
8ca02f3c	225	{
568fa3fa MS	226	timeout.tv_sec = 5;
	227	timeout.tv_usec = 0;
	228
	229	if (select(nfds, &input, &output, NULL, &timeout) < 0)
8ca02f3c	230	{
	231	/*
	232	* Pause printing to clear any pending errors...
	233	*/
	234
ef55b745	235	if (errno == ENXIO && offline != 1 && update_state)
8ca02f3c	236	{
c5571a1d	237	fputs("STATE: +offline-report\n", stderr);
0837b7e8	238	_cupsLangPrintFilter(stderr, "INFO",
f3c17241	239	_("The printer is not connected."));
8ca02f3c	240	offline = 1;
8ca02f3c	241	}
b94498cf	242	else if (errno == EINTR && total_bytes == 0)
	243	{
	244	fputs("DEBUG: Received an interrupt before any bytes were "
c8fef167	245	"written, aborting.\n", stderr);
b94498cf	246	return (0);
b94498cf	247	}
8ca02f3c	248
	249	sleep(1);
	250	continue;
	251	}
	252	}
ed486911	253
f7deaa1a	254	/*
	255	* Check if we have a side-channel request ready...
	256	*/
	257
	258	if (side_cb && FD_ISSET(CUPS_SC_FD, &input))
dd1abb6b MS	259	{
	260	/*
	261	* Do the side-channel request, then start back over in the select
	262	* loop since it may have read from print_fd...
	263	*/
	264
18ecb428 MS	265	if ((*side_cb)(print_fd, device_fd, snmp_fd, addr, use_bc))
18ecb428 MS	266	side_cb = NULL;
dd1abb6b MS	267	continue;
dd1abb6b MS	268	}
f7deaa1a	269
ed486911	270	/*
	271	* Check if we have back-channel data ready...
	272	*/
	273
	274	if (FD_ISSET(device_fd, &input))
	275	{
	276	if ((bc_bytes = read(device_fd, bc_buffer, sizeof(bc_buffer))) > 0)
	277	{
	278	fprintf(stderr,
4d301e69	279	"DEBUG: Received " CUPS_LLFMT " bytes of back-channel data\n",
ed486911	280	CUPS_LLCAST bc_bytes);
7e86f2f6	281	cupsBackChannelWrite(bc_buffer, (size_t)bc_bytes, 1.0);
ed486911	282	}
4b3f67ff MS	283	else if (bc_bytes < 0 && errno != EAGAIN && errno != EINTR)
	284	{
	285	fprintf(stderr, "DEBUG: Error reading back-channel data: %s\n",
	286	strerror(errno));
	287	use_bc = 0;
	288	}
7cf5915e MS	289	else if (bc_bytes == 0)
7cf5915e MS	290	use_bc = 0;
ed486911	291	}
	292
	293	/*
	294	* Check if we have print data ready...
	295	*/
	296
	297	if (FD_ISSET(print_fd, &input))
	298	{
	299	if ((print_bytes = read(print_fd, print_buffer,
	300	sizeof(print_buffer))) < 0)
	301	{
	302	/*
	303	* Read error - bail if we don't see EAGAIN or EINTR...
	304	*/
	305
0b1399a2	306	if (errno != EAGAIN && errno != EINTR)
ed486911	307	{
f3c17241 MS	308	fprintf(stderr, "DEBUG: Read failed: %s\n", strerror(errno));
	309	_cupsLangPrintFilter(stderr, "ERROR",
	310	_("Unable to read print data."));
ed486911	311	return (-1);
	312	}
	313
	314	print_bytes = 0;
	315	}
	316	else if (print_bytes == 0)
	317	{
	318	/*
	319	* End of file, break out of the loop...
	320	*/
	321
	322	break;
	323	}
	324
	325	print_ptr = print_buffer;
8ca02f3c	326
	327	fprintf(stderr, "DEBUG: Read %d bytes of print data...\n",
	328	(int)print_bytes);
ed486911	329	}
	330
	331	/*
	332	* Check if the device is ready to receive data and we have data to
	333	* send...
	334	*/
	335
	336	if (print_bytes && FD_ISSET(device_fd, &output))
	337	{
7e86f2f6	338	if ((bytes = write(device_fd, print_ptr, (size_t)print_bytes)) < 0)
ed486911	339	{
	340	/*
	341	* Write error - bail if we don't see an error we can retry...
	342	*/
	343
	344	if (errno == ENOSPC)
	345	{
ef55b745	346	if (paperout != 1 && update_state)
ed486911	347	{
c5571a1d	348	fputs("STATE: +media-empty-warning\n", stderr);
0837b7e8	349	fputs("DEBUG: Out of paper\n", stderr);
ed486911	350	paperout = 1;
	351	}
	352	}
8ca02f3c	353	else if (errno == ENXIO)
8ca02f3c	354	{
ef55b745	355	if (offline != 1 && update_state)
8ca02f3c	356	{
c5571a1d	357	fputs("STATE: +offline-report\n", stderr);
0837b7e8	358	_cupsLangPrintFilter(stderr, "INFO",
f3c17241	359	_("The printer is not connected."));
8ca02f3c	360	offline = 1;
	361	}
	362	}
ed486911	363	else if (errno != EAGAIN && errno != EINTR && errno != ENOTTY)
ed486911	364	{
0837b7e8	365	_cupsLangPrintError("ERROR", _("Unable to write print data"));
ed486911	366	return (-1);
	367	}
	368	}
	369	else
	370	{
ef55b745	371	if (paperout && update_state)
ed486911	372	{
c5571a1d	373	fputs("STATE: -media-empty-warning\n", stderr);
ed486911	374	paperout = 0;
	375	}
	376
ef55b745	377	if (offline && update_state)
8ca02f3c	378	{
c5571a1d	379	fputs("STATE: -offline-report\n", stderr);
f3c17241 MS	380	_cupsLangPrintFilter(stderr, "INFO",
f3c17241 MS	381	_("The printer is now connected."));
8ca02f3c	382	offline = 0;
	383	}
	384
	385	fprintf(stderr, "DEBUG: Wrote %d bytes of print data...\n", (int)bytes);
ed486911	386
	387	print_bytes -= bytes;
	388	print_ptr += bytes;
	389	total_bytes += bytes;
	390	}
	391	}
568fa3fa MS	392
	393	/*
	394	* Do SNMP updates periodically...
	395	*/
	396
	397	if (snmp_fd >= 0 && time(&curtime) >= snmp_update)
	398	{
	399	if (backendSNMPSupplies(snmp_fd, addr, NULL, NULL))
	400	snmp_update = INT_MAX;
	401	else
	402	snmp_update = curtime + 5;
	403	}
ed486911	404	}
	405
	406	/*
	407	* Return with success...
	408	*/
	409
	410	return (total_bytes);
	411	}
	412
	413
	414	/*
c8fef167 MS	415	* 'backendWaitLoop()' - Wait for input from stdin while handling side-channel
	416	* queries.
	417	*/
	418
	419	int /* O - 1 if data is ready, 0 if not */
	420	backendWaitLoop(
	421	int snmp_fd, /* I - SNMP socket or -1 if none */
	422	http_addr_t addr, / I - Address of device */
f14324a7	423	int use_bc, /* I - Use back-channel? */
c8fef167 MS	424	_cups_sccb_t side_cb) /* I - Side-channel callback */
c8fef167 MS	425	{
82cc1f9a MS	426	int nfds; /* Number of file descriptors */
	427	fd_set input; /* Input set for reading */
	428	time_t curtime = 0, /* Current time */
	429	snmp_update = 0;/* Last SNMP status update */
	430	struct timeval timeout; /* Timeout for select() */
c8fef167 MS	431
	432
	433	fprintf(stderr, "DEBUG: backendWaitLoop(snmp_fd=%d, addr=%p, side_cb=%p)\n",
	434	snmp_fd, addr, side_cb);
	435
	436	/*
	437	* Now loop until we receive data from stdin...
	438	*/
	439
82cc1f9a MS	440	if (snmp_fd >= 0)
	441	snmp_update = time(NULL) + 5;
	442
c8fef167 MS	443	for (;;)
	444	{
	445	/*
	446	* Use select() to determine whether we have data to copy around...
	447	*/
	448
	449	FD_ZERO(&input);
	450	FD_SET(0, &input);
	451	if (side_cb)
	452	FD_SET(CUPS_SC_FD, &input);
	453
82cc1f9a MS	454	if (snmp_fd >= 0)
	455	{
	456	curtime = time(NULL);
	457	timeout.tv_sec = curtime >= snmp_update ? 0 : snmp_update - curtime;
	458	timeout.tv_usec = 0;
	459
	460	nfds = select(CUPS_SC_FD + 1, &input, NULL, NULL, &timeout);
	461	}
	462	else
	463	nfds = select(CUPS_SC_FD + 1, &input, NULL, NULL, NULL);
	464
	465	if (nfds < 0)
c8fef167 MS	466	{
	467	/*
	468	* Pause printing to clear any pending errors...
	469	*/
	470
	471	if (errno == EINTR)
	472	{
	473	fputs("DEBUG: Received an interrupt before any bytes were "
	474	"written, aborting.\n", stderr);
	475	return (0);
	476	}
	477
	478	sleep(1);
	479	continue;
	480	}
	481
	482	/*
	483	* Check for input on stdin...
	484	*/
	485
	486	if (FD_ISSET(0, &input))
	487	break;
	488
	489	/*
	490	* Check if we have a side-channel request ready...
	491	*/
	492
	493	if (side_cb && FD_ISSET(CUPS_SC_FD, &input))
	494	{
	495	/*
	496	* Do the side-channel request, then start back over in the select
	497	* loop since it may have read from print_fd...
	498	*/
	499
f14324a7	500	if ((*side_cb)(0, -1, snmp_fd, addr, use_bc))
c8fef167 MS	501	side_cb = NULL;
	502	continue;
	503	}
	504
	505	/*
	506	* Do SNMP updates periodically...
	507	*/
	508
82cc1f9a	509	if (snmp_fd >= 0 && curtime >= snmp_update)
c8fef167 MS	510	{
c8fef167 MS	511	if (backendSNMPSupplies(snmp_fd, addr, NULL, NULL))
82cc1f9a	512	snmp_fd = -1;
c8fef167 MS	513	else
	514	snmp_update = curtime + 5;
	515	}
	516	}
	517
	518	/*
	519	* Return with success...
	520	*/
	521
	522	return (1);
	523	}