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/*
* "$Id: runloop.c 5776 2006-07-26 20:55:13Z mike $"
*
* Common run loop API for the Common UNIX Printing System (CUPS).
*
* Copyright 2006 by Easy Software Products, all rights reserved.
*
* These coded instructions, statements, and computer programs are the
* property of Easy Software Products and are protected by Federal
* copyright law. Distribution and use rights are outlined in the file
* "LICENSE" which should have been included with this file. If this
* file is missing or damaged please contact Easy Software Products
* at:
*
* Attn: CUPS Licensing Information
* Easy Software Products
* 44141 Airport View Drive, Suite 204
* Hollywood, Maryland 20636 USA
*
* Voice: (301) 373-9600
* EMail: cups-info@cups.org
* WWW: http://www.cups.org
*
* This file is subject to the Apple OS-Developed Software exception.
*
* Contents:
*
* backendRunLoop() - Read and write print and back-channel data.
*/
/*
* Include necessary headers.
*/
#include "backend-private.h"
#ifdef __hpux
# include <sys/time.h>
#else
# include <sys/select.h>
#endif /* __hpux */
/*
* '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 use_bc) /* I - Use back-channel? */
{
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 */
#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, use_bc=%d)\n",
print_fd, device_fd, use_bc);
/*
* 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 */
}
/*
* 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 = 0, paperout = 0, 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);
FD_ZERO(&output);
if (print_bytes || !use_bc)
FD_SET(device_fd, &output);
if (use_bc)
{
if (select(nfds, &input, &output, NULL, NULL) < 0)
{
/*
* Pause printing to clear any pending errors...
*/
if (errno == ENXIO && !offline)
{
fputs("STATE: +offline-error\n", stderr);
fputs("INFO: Printer is currently off-line.\n", stderr);
offline = 1;
}
sleep(1);
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, bc_bytes, 1.0);
}
}
/*
* 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)
{
perror("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, print_bytes)) < 0)
{
/*
* Write error - bail if we don't see an error we can retry...
*/
if (errno == ENOSPC)
{
if (!paperout)
{
fputs("ERROR: Out of paper!\n", stderr);
fputs("STATUS: +media-tray-empty-error\n", stderr);
paperout = 1;
}
}
else if (errno == ENXIO)
{
if (!offline)
{
fputs("STATE: +offline-error\n", stderr);
fputs("INFO: Printer is currently off-line.\n", stderr);
offline = 1;
}
}
else if (errno != EAGAIN && errno != EINTR && errno != ENOTTY)
{
perror("ERROR: Unable to write print data");
return (-1);
}
}
else
{
if (paperout)
{
fputs("STATUS: -media-tray-empty-error\n", stderr);
paperout = 0;
}
if (offline)
{
fputs("STATE: -offline-error\n", stderr);
fputs("INFO: Printer is now on-line.\n", stderr);
offline = 0;
}
fprintf(stderr, "DEBUG: Wrote %d bytes of print data...\n", (int)bytes);
print_bytes -= bytes;
print_ptr += bytes;
total_bytes += bytes;
}
}
}
/*
* Return with success...
*/
return (total_bytes);
}
/*
* End of "$Id: runloop.c 5776 2006-07-26 20:55:13Z mike $".
*/
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