cups/backend/runloop.c

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/*
* Common run loop APIs for CUPS backends.
*
* Copyright © 2007-2014 by Apple Inc.
* Copyright © 2006-2007 by Easy Software Products, all rights reserved.
*
* Licensed under Apache License v2.0. See the file "LICENSE" for more
* information.
*/
/*
* 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);
}