backend/runloop.c

   1 /*
   2  * Common run loop APIs for CUPS backends.
   3  *
   4  * Copyright 2007-2014 by Apple Inc.
   5  * Copyright 2006-2007 by Easy Software Products, all rights reserved.
   6  *
   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/".
  12  *
  13  * This file is subject to the Apple OS-Developed Software exception.
  14  */
  15
  16 /*
  17  * Include necessary headers.
  18  */
  19
  20 #include "backend-private.h"
  21 #include <limits.h>
  22 #include <sys/select.h>
  23
  24
  25 /*
  26  * 'backendDrainOutput()' - Drain pending print data to the device.
  27  */
  28
  29 int                                     /* O - 0 on success, -1 on error */
  30 backendDrainOutput(int print_fd,        /* I - Print file descriptor */
  31                    int device_fd)       /* I - Device file descriptor */
  32 {
  33   int           nfds;                   /* Maximum file descriptor value + 1 */
  34   fd_set        input;                  /* Input set for reading */
  35   ssize_t       print_bytes,            /* Print bytes read */
  36                 bytes;                  /* Bytes written */
  37   char          print_buffer[8192],     /* Print data buffer */
  38                 *print_ptr;             /* Pointer into print data buffer */
  39   struct timeval timeout;               /* Timeout for read... */
  40
  41
  42   fprintf(stderr, "DEBUG: backendDrainOutput(print_fd=%d, device_fd=%d)\n",
  43           print_fd, device_fd);
  44
  45  /*
  46   * Figure out the maximum file descriptor value to use with select()...
  47   */
  48
  49   nfds = (print_fd > device_fd ? print_fd : device_fd) + 1;
  50
  51  /*
  52   * Now loop until we are out of data from print_fd...
  53   */
  54
  55   for (;;)
  56   {
  57    /*
  58     * Use select() to determine whether we have data to copy around...
  59     */
  60
  61     FD_ZERO(&input);
  62     FD_SET(print_fd, &input);
  63
  64     timeout.tv_sec  = 0;
  65     timeout.tv_usec = 0;
  66
  67     if (select(nfds, &input, NULL, NULL, &timeout) < 0)
  68       return (-1);
  69
  70     if (!FD_ISSET(print_fd, &input))
  71       return (0);
  72
  73     if ((print_bytes = read(print_fd, print_buffer,
  74                             sizeof(print_buffer))) < 0)
  75     {
  76      /*
  77       * Read error - bail if we don't see EAGAIN or EINTR...
  78       */
  79
  80       if (errno != EAGAIN && errno != EINTR)
  81       {
  82         fprintf(stderr, "DEBUG: Read failed: %s\n", strerror(errno));
  83         _cupsLangPrintFilter(stderr, "ERROR", _("Unable to read print data."));
  84         return (-1);
  85       }
  86
  87       print_bytes = 0;
  88     }
  89     else if (print_bytes == 0)
  90     {
  91      /*
  92       * End of file, return...
  93       */
  94
  95       return (0);
  96     }
  97
  98     fprintf(stderr, "DEBUG: Read %d bytes of print data...\n",
  99             (int)print_bytes);
 100
 101     for (print_ptr = print_buffer; print_bytes > 0;)
 102     {
 103       if ((bytes = write(device_fd, print_ptr, (size_t)print_bytes)) < 0)
 104       {
 105        /*
 106         * Write error - bail if we don't see an error we can retry...
 107         */
 108
 109         if (errno != ENOSPC && errno != ENXIO && errno != EAGAIN &&
 110             errno != EINTR && errno != ENOTTY)
 111         {
 112           _cupsLangPrintError("ERROR", _("Unable to write print data"));
 113           return (-1);
 114         }
 115       }
 116       else
 117       {
 118         fprintf(stderr, "DEBUG: Wrote %d bytes of print data...\n", (int)bytes);
 119
 120         print_bytes -= bytes;
 121         print_ptr   += bytes;
 122       }
 123     }
 124   }
 125 }
 126
 127
 128 /*
 129  * 'backendRunLoop()' - Read and write print and back-channel data.
 130  */
 131
 132 ssize_t                                 /* O - Total bytes on success, -1 on error */
 133 backendRunLoop(
 134     int          print_fd,              /* I - Print file descriptor */
 135     int          device_fd,             /* I - Device file descriptor */
 136     int          snmp_fd,               /* I - SNMP socket or -1 if none */
 137     http_addr_t  *addr,                 /* I - Address of device */
 138     int          use_bc,                /* I - Use back-channel? */
 139     int          update_state,          /* I - Update printer-state-reasons? */
 140     _cups_sccb_t side_cb)               /* I - Side-channel callback */
 141 {
 142   int           nfds;                   /* Maximum file descriptor value + 1 */
 143   fd_set        input,                  /* Input set for reading */
 144                 output;                 /* Output set for writing */
 145   ssize_t       print_bytes,            /* Print bytes read */
 146                 bc_bytes,               /* Backchannel bytes read */
 147                 total_bytes,            /* Total bytes written */
 148                 bytes;                  /* Bytes written */
 149   int           paperout;               /* "Paper out" status */
 150   int           offline;                /* "Off-line" status */
 151   char          print_buffer[8192],     /* Print data buffer */
 152                 *print_ptr,             /* Pointer into print data buffer */
 153                 bc_buffer[1024];        /* Back-channel data buffer */
 154   struct timeval timeout;               /* Timeout for select() */
 155   time_t        curtime,                /* Current time */
 156                 snmp_update = 0;
 157 #if defined(HAVE_SIGACTION) && !defined(HAVE_SIGSET)
 158   struct sigaction action;              /* Actions for POSIX signals */
 159 #endif /* HAVE_SIGACTION && !HAVE_SIGSET */
 160
 161
 162   fprintf(stderr,
 163           "DEBUG: backendRunLoop(print_fd=%d, device_fd=%d, snmp_fd=%d, "
 164           "addr=%p, use_bc=%d, side_cb=%p)\n",
 165           print_fd, device_fd, snmp_fd, addr, use_bc, side_cb);
 166
 167  /*
 168   * If we are printing data from a print driver on stdin, ignore SIGTERM
 169   * so that the driver can finish out any page data, e.g. to eject the
 170   * current page.  We only do this for stdin printing as otherwise there
 171   * is no way to cancel a raw print job...
 172   */
 173
 174   if (!print_fd)
 175   {
 176 #ifdef HAVE_SIGSET /* Use System V signals over POSIX to avoid bugs */
 177     sigset(SIGTERM, SIG_IGN);
 178 #elif defined(HAVE_SIGACTION)
 179     memset(&action, 0, sizeof(action));
 180
 181     sigemptyset(&action.sa_mask);
 182     action.sa_handler = SIG_IGN;
 183     sigaction(SIGTERM, &action, NULL);
 184 #else
 185     signal(SIGTERM, SIG_IGN);
 186 #endif /* HAVE_SIGSET */
 187   }
 188   else if (print_fd < 0)
 189   {
 190    /*
 191     * Copy print data from stdin, but don't mess with the signal handlers...
 192     */
 193
 194     print_fd = 0;
 195   }
 196
 197  /*
 198   * Figure out the maximum file descriptor value to use with select()...
 199   */
 200
 201   nfds = (print_fd > device_fd ? print_fd : device_fd) + 1;
 202
 203  /*
 204   * Now loop until we are out of data from print_fd...
 205   */
 206
 207   for (print_bytes = 0, print_ptr = print_buffer, offline = -1,
 208            paperout = -1, total_bytes = 0;;)
 209   {
 210    /*
 211     * Use select() to determine whether we have data to copy around...
 212     */
 213
 214     FD_ZERO(&input);
 215     if (!print_bytes)
 216       FD_SET(print_fd, &input);
 217     if (use_bc)
 218       FD_SET(device_fd, &input);
 219     if (!print_bytes && side_cb)
 220       FD_SET(CUPS_SC_FD, &input);
 221
 222     FD_ZERO(&output);
 223     if (print_bytes || (!use_bc && !side_cb))
 224       FD_SET(device_fd, &output);
 225
 226     if (use_bc || side_cb)
 227     {
 228       timeout.tv_sec  = 5;
 229       timeout.tv_usec = 0;
 230
 231       if (select(nfds, &input, &output, NULL, &timeout) < 0)
 232       {
 233        /*
 234         * Pause printing to clear any pending errors...
 235         */
 236
 237         if (errno == ENXIO && offline != 1 && update_state)
 238         {
 239           fputs("STATE: +offline-report\n", stderr);
 240           _cupsLangPrintFilter(stderr, "INFO",
 241                                _("The printer is not connected."));
 242           offline = 1;
 243         }
 244         else if (errno == EINTR && total_bytes == 0)
 245         {
 246           fputs("DEBUG: Received an interrupt before any bytes were "
 247                 "written, aborting.\n", stderr);
 248           return (0);
 249         }
 250
 251         sleep(1);
 252         continue;
 253       }
 254     }
 255
 256    /*
 257     * Check if we have a side-channel request ready...
 258     */
 259
 260     if (side_cb && FD_ISSET(CUPS_SC_FD, &input))
 261     {
 262      /*
 263       * Do the side-channel request, then start back over in the select
 264       * loop since it may have read from print_fd...
 265       */
 266
 267       if ((*side_cb)(print_fd, device_fd, snmp_fd, addr, use_bc))
 268         side_cb = NULL;
 269       continue;
 270     }
 271
 272    /*
 273     * Check if we have back-channel data ready...
 274     */
 275
 276     if (FD_ISSET(device_fd, &input))
 277     {
 278       if ((bc_bytes = read(device_fd, bc_buffer, sizeof(bc_buffer))) > 0)
 279       {
 280         fprintf(stderr,
 281                 "DEBUG: Received " CUPS_LLFMT " bytes of back-channel data\n",
 282                 CUPS_LLCAST bc_bytes);
 283         cupsBackChannelWrite(bc_buffer, (size_t)bc_bytes, 1.0);
 284       }
 285       else if (bc_bytes < 0 && errno != EAGAIN && errno != EINTR)
 286       {
 287         fprintf(stderr, "DEBUG: Error reading back-channel data: %s\n",
 288                 strerror(errno));
 289         use_bc = 0;
 290       }
 291       else if (bc_bytes == 0)
 292         use_bc = 0;
 293     }
 294
 295    /*
 296     * Check if we have print data ready...
 297     */
 298
 299     if (FD_ISSET(print_fd, &input))
 300     {
 301       if ((print_bytes = read(print_fd, print_buffer,
 302                               sizeof(print_buffer))) < 0)
 303       {
 304        /*
 305         * Read error - bail if we don't see EAGAIN or EINTR...
 306         */
 307
 308         if (errno != EAGAIN && errno != EINTR)
 309         {
 310           fprintf(stderr, "DEBUG: Read failed: %s\n", strerror(errno));
 311           _cupsLangPrintFilter(stderr, "ERROR",
 312                                _("Unable to read print data."));
 313           return (-1);
 314         }
 315
 316         print_bytes = 0;
 317       }
 318       else if (print_bytes == 0)
 319       {
 320        /*
 321         * End of file, break out of the loop...
 322         */
 323
 324         break;
 325       }
 326
 327       print_ptr = print_buffer;
 328
 329       fprintf(stderr, "DEBUG: Read %d bytes of print data...\n",
 330               (int)print_bytes);
 331     }
 332
 333    /*
 334     * Check if the device is ready to receive data and we have data to
 335     * send...
 336     */
 337
 338     if (print_bytes && FD_ISSET(device_fd, &output))
 339     {
 340       if ((bytes = write(device_fd, print_ptr, (size_t)print_bytes)) < 0)
 341       {
 342        /*
 343         * Write error - bail if we don't see an error we can retry...
 344         */
 345
 346         if (errno == ENOSPC)
 347         {
 348           if (paperout != 1 && update_state)
 349           {
 350             fputs("STATE: +media-empty-warning\n", stderr);
 351             fputs("DEBUG: Out of paper\n", stderr);
 352             paperout = 1;
 353           }
 354         }
 355         else if (errno == ENXIO)
 356         {
 357           if (offline != 1 && update_state)
 358           {
 359             fputs("STATE: +offline-report\n", stderr);
 360             _cupsLangPrintFilter(stderr, "INFO",
 361                                  _("The printer is not connected."));
 362             offline = 1;
 363           }
 364         }
 365         else if (errno != EAGAIN && errno != EINTR && errno != ENOTTY)
 366         {
 367           _cupsLangPrintError("ERROR", _("Unable to write print data"));
 368           return (-1);
 369         }
 370       }
 371       else
 372       {
 373         if (paperout && update_state)
 374         {
 375           fputs("STATE: -media-empty-warning\n", stderr);
 376           paperout = 0;
 377         }
 378
 379         if (offline && update_state)
 380         {
 381           fputs("STATE: -offline-report\n", stderr);
 382           _cupsLangPrintFilter(stderr, "INFO",
 383                                _("The printer is now connected."));
 384           offline = 0;
 385         }
 386
 387         fprintf(stderr, "DEBUG: Wrote %d bytes of print data...\n", (int)bytes);
 388
 389         print_bytes -= bytes;
 390         print_ptr   += bytes;
 391         total_bytes += bytes;
 392       }
 393     }
 394
 395    /*
 396     * Do SNMP updates periodically...
 397     */
 398
 399     if (snmp_fd >= 0 && time(&curtime) >= snmp_update)
 400     {
 401       if (backendSNMPSupplies(snmp_fd, addr, NULL, NULL))
 402         snmp_update = INT_MAX;
 403       else
 404         snmp_update = curtime + 5;
 405     }
 406   }
 407
 408  /*
 409   * Return with success...
 410   */
 411
 412   return (total_bytes);
 413 }
 414
 415
 416 /*
 417  * 'backendWaitLoop()' - Wait for input from stdin while handling side-channel
 418  *                       queries.
 419  */
 420
 421 int                                     /* O - 1 if data is ready, 0 if not */
 422 backendWaitLoop(
 423     int          snmp_fd,               /* I - SNMP socket or -1 if none */
 424     http_addr_t  *addr,                 /* I - Address of device */
 425     int          use_bc,                /* I - Use back-channel? */
 426     _cups_sccb_t side_cb)               /* I - Side-channel callback */
 427 {
 428   int                   nfds;           /* Number of file descriptors */
 429   fd_set                input;          /* Input set for reading */
 430   time_t                curtime = 0,    /* Current time */
 431                         snmp_update = 0;/* Last SNMP status update */
 432   struct timeval        timeout;        /* Timeout for select() */
 433
 434
 435   fprintf(stderr, "DEBUG: backendWaitLoop(snmp_fd=%d, addr=%p, side_cb=%p)\n",
 436           snmp_fd, addr, side_cb);
 437
 438  /*
 439   * Now loop until we receive data from stdin...
 440   */
 441
 442   if (snmp_fd >= 0)
 443     snmp_update = time(NULL) + 5;
 444
 445   for (;;)
 446   {
 447    /*
 448     * Use select() to determine whether we have data to copy around...
 449     */
 450
 451     FD_ZERO(&input);
 452     FD_SET(0, &input);
 453     if (side_cb)
 454       FD_SET(CUPS_SC_FD, &input);
 455
 456     if (snmp_fd >= 0)
 457     {
 458       curtime         = time(NULL);
 459       timeout.tv_sec  = curtime >= snmp_update ? 0 : snmp_update - curtime;
 460       timeout.tv_usec = 0;
 461
 462       nfds = select(CUPS_SC_FD + 1, &input, NULL, NULL, &timeout);
 463     }
 464     else
 465       nfds = select(CUPS_SC_FD + 1, &input, NULL, NULL, NULL);
 466
 467     if (nfds < 0)
 468     {
 469      /*
 470       * Pause printing to clear any pending errors...
 471       */
 472
 473       if (errno == EINTR)
 474       {
 475         fputs("DEBUG: Received an interrupt before any bytes were "
 476               "written, aborting.\n", stderr);
 477         return (0);
 478       }
 479
 480       sleep(1);
 481       continue;
 482     }
 483
 484    /*
 485     * Check for input on stdin...
 486     */
 487
 488     if (FD_ISSET(0, &input))
 489       break;
 490
 491    /*
 492     * Check if we have a side-channel request ready...
 493     */
 494
 495     if (side_cb && FD_ISSET(CUPS_SC_FD, &input))
 496     {
 497      /*
 498       * Do the side-channel request, then start back over in the select
 499       * loop since it may have read from print_fd...
 500       */
 501
 502       if ((*side_cb)(0, -1, snmp_fd, addr, use_bc))
 503         side_cb = NULL;
 504       continue;
 505     }
 506
 507    /*
 508     * Do SNMP updates periodically...
 509     */
 510
 511     if (snmp_fd >= 0 && curtime >= snmp_update)
 512     {
 513       if (backendSNMPSupplies(snmp_fd, addr, NULL, NULL))
 514         snmp_fd = -1;
 515       else
 516         snmp_update = curtime + 5;
 517     }
 518   }
 519
 520  /*
 521   * Return with success...
 522   */
 523
 524   return (1);
 525 }