backend/runloop.c

   1 /*
   2  * "$Id$"
   3  *
   4  *   Common run loop APIs for CUPS backends.
   5  *
   6  *   Copyright 2007-2012 by Apple Inc.
   7  *   Copyright 2006-2007 by Easy Software Products, all rights reserved.
   8  *
   9  *   These coded instructions, statements, and computer programs are the
  10  *   property of Apple Inc. and are protected by Federal copyright
  11  *   law.  Distribution and use rights are outlined in the file "LICENSE.txt"
  12  *   "LICENSE" which should have been included with this file.  If this
  13  *   file is missing or damaged, see the license at "http://www.cups.org/".
  14  *
  15  *   This file is subject to the Apple OS-Developed Software exception.
  16  *
  17  * Contents:
  18  *
  19  *   backendDrainOutput() - Drain pending print data to the device.
  20  *   backendRunLoop()     - Read and write print and back-channel data.
  21  *   backendWaitLoop()    - Wait for input from stdin while handling
  22  *                          side-channel queries.
  23  */
  24
  25 /*
  26  * Include necessary headers.
  27  */
  28
  29 #include "backend-private.h"
  30 #include <limits.h>
  31 #ifdef __hpux
  32 #  include <sys/time.h>
  33 #else
  34 #  include <sys/select.h>
  35 #endif /* __hpux */
  36
  37
  38 /*
  39  * 'backendDrainOutput()' - Drain pending print data to the device.
  40  */
  41
  42 int                                     /* O - 0 on success, -1 on error */
  43 backendDrainOutput(int print_fd,        /* I - Print file descriptor */
  44                    int device_fd)       /* I - Device file descriptor */
  45 {
  46   int           nfds;                   /* Maximum file descriptor value + 1 */
  47   fd_set        input;                  /* Input set for reading */
  48   ssize_t       print_bytes,            /* Print bytes read */
  49                 bytes;                  /* Bytes written */
  50   char          print_buffer[8192],     /* Print data buffer */
  51                 *print_ptr;             /* Pointer into print data buffer */
  52   struct timeval timeout;               /* Timeout for read... */
  53
  54
  55   fprintf(stderr, "DEBUG: backendDrainOutput(print_fd=%d, device_fd=%d)\n",
  56           print_fd, device_fd);
  57
  58  /*
  59   * Figure out the maximum file descriptor value to use with select()...
  60   */
  61
  62   nfds = (print_fd > device_fd ? print_fd : device_fd) + 1;
  63
  64  /*
  65   * Now loop until we are out of data from print_fd...
  66   */
  67
  68   for (;;)
  69   {
  70    /*
  71     * Use select() to determine whether we have data to copy around...
  72     */
  73
  74     FD_ZERO(&input);
  75     FD_SET(print_fd, &input);
  76
  77     timeout.tv_sec  = 0;
  78     timeout.tv_usec = 0;
  79
  80     if (select(nfds, &input, NULL, NULL, &timeout) < 0)
  81       return (-1);
  82
  83     if (!FD_ISSET(print_fd, &input))
  84       return (0);
  85
  86     if ((print_bytes = read(print_fd, print_buffer,
  87                             sizeof(print_buffer))) < 0)
  88     {
  89      /*
  90       * Read error - bail if we don't see EAGAIN or EINTR...
  91       */
  92
  93       if (errno != EAGAIN || errno != EINTR)
  94       {
  95         fprintf(stderr, "DEBUG: Read failed: %s\n", strerror(errno));
  96         _cupsLangPrintFilter(stderr, "ERROR", _("Unable to read print data."));
  97         return (-1);
  98       }
  99
 100       print_bytes = 0;
 101     }
 102     else if (print_bytes == 0)
 103     {
 104      /*
 105       * End of file, return...
 106       */
 107
 108       return (0);
 109     }
 110
 111     fprintf(stderr, "DEBUG: Read %d bytes of print data...\n",
 112             (int)print_bytes);
 113
 114     for (print_ptr = print_buffer; print_bytes > 0;)
 115     {
 116       if ((bytes = write(device_fd, print_ptr, print_bytes)) < 0)
 117       {
 118        /*
 119         * Write error - bail if we don't see an error we can retry...
 120         */
 121
 122         if (errno != ENOSPC && errno != ENXIO && errno != EAGAIN &&
 123             errno != EINTR && errno != ENOTTY)
 124         {
 125           _cupsLangPrintError("ERROR", _("Unable to write print data"));
 126           return (-1);
 127         }
 128       }
 129       else
 130       {
 131         fprintf(stderr, "DEBUG: Wrote %d bytes of print data...\n", (int)bytes);
 132
 133         print_bytes -= bytes;
 134         print_ptr   += bytes;
 135       }
 136     }
 137   }
 138 }
 139
 140
 141 /*
 142  * 'backendRunLoop()' - Read and write print and back-channel data.
 143  */
 144
 145 ssize_t                                 /* O - Total bytes on success, -1 on error */
 146 backendRunLoop(
 147     int          print_fd,              /* I - Print file descriptor */
 148     int          device_fd,             /* I - Device file descriptor */
 149     int          snmp_fd,               /* I - SNMP socket or -1 if none */
 150     http_addr_t  *addr,                 /* I - Address of device */
 151     int          use_bc,                /* I - Use back-channel? */
 152     int          update_state,          /* I - Update printer-state-reasons? */
 153     _cups_sccb_t side_cb)               /* I - Side-channel callback */
 154 {
 155   int           nfds;                   /* Maximum file descriptor value + 1 */
 156   fd_set        input,                  /* Input set for reading */
 157                 output;                 /* Output set for writing */
 158   ssize_t       print_bytes,            /* Print bytes read */
 159                 bc_bytes,               /* Backchannel bytes read */
 160                 total_bytes,            /* Total bytes written */
 161                 bytes;                  /* Bytes written */
 162   int           paperout;               /* "Paper out" status */
 163   int           offline;                /* "Off-line" status */
 164   char          print_buffer[8192],     /* Print data buffer */
 165                 *print_ptr,             /* Pointer into print data buffer */
 166                 bc_buffer[1024];        /* Back-channel data buffer */
 167   struct timeval timeout;               /* Timeout for select() */
 168   time_t        curtime,                /* Current time */
 169                 snmp_update = 0;
 170 #if defined(HAVE_SIGACTION) && !defined(HAVE_SIGSET)
 171   struct sigaction action;              /* Actions for POSIX signals */
 172 #endif /* HAVE_SIGACTION && !HAVE_SIGSET */
 173
 174
 175   fprintf(stderr,
 176           "DEBUG: backendRunLoop(print_fd=%d, device_fd=%d, snmp_fd=%d, "
 177           "addr=%p, use_bc=%d, side_cb=%p)\n",
 178           print_fd, device_fd, snmp_fd, addr, use_bc, side_cb);
 179
 180  /*
 181   * If we are printing data from a print driver on stdin, ignore SIGTERM
 182   * so that the driver can finish out any page data, e.g. to eject the
 183   * current page.  We only do this for stdin printing as otherwise there
 184   * is no way to cancel a raw print job...
 185   */
 186
 187   if (!print_fd)
 188   {
 189 #ifdef HAVE_SIGSET /* Use System V signals over POSIX to avoid bugs */
 190     sigset(SIGTERM, SIG_IGN);
 191 #elif defined(HAVE_SIGACTION)
 192     memset(&action, 0, sizeof(action));
 193
 194     sigemptyset(&action.sa_mask);
 195     action.sa_handler = SIG_IGN;
 196     sigaction(SIGTERM, &action, NULL);
 197 #else
 198     signal(SIGTERM, SIG_IGN);
 199 #endif /* HAVE_SIGSET */
 200   }
 201   else if (print_fd < 0)
 202   {
 203    /*
 204     * Copy print data from stdin, but don't mess with the signal handlers...
 205     */
 206
 207     print_fd = 0;
 208   }
 209
 210  /*
 211   * Figure out the maximum file descriptor value to use with select()...
 212   */
 213
 214   nfds = (print_fd > device_fd ? print_fd : device_fd) + 1;
 215
 216  /*
 217   * Now loop until we are out of data from print_fd...
 218   */
 219
 220   for (print_bytes = 0, print_ptr = print_buffer, offline = -1,
 221            paperout = -1, total_bytes = 0;;)
 222   {
 223    /*
 224     * Use select() to determine whether we have data to copy around...
 225     */
 226
 227     FD_ZERO(&input);
 228     if (!print_bytes)
 229       FD_SET(print_fd, &input);
 230     if (use_bc)
 231       FD_SET(device_fd, &input);
 232     if (!print_bytes && side_cb)
 233       FD_SET(CUPS_SC_FD, &input);
 234
 235     FD_ZERO(&output);
 236     if (print_bytes || (!use_bc && !side_cb))
 237       FD_SET(device_fd, &output);
 238
 239     if (use_bc || side_cb)
 240     {
 241       timeout.tv_sec  = 5;
 242       timeout.tv_usec = 0;
 243
 244       if (select(nfds, &input, &output, NULL, &timeout) < 0)
 245       {
 246        /*
 247         * Pause printing to clear any pending errors...
 248         */
 249
 250         if (errno == ENXIO && offline != 1 && update_state)
 251         {
 252           fputs("STATE: +offline-report\n", stderr);
 253           _cupsLangPrintFilter(stderr, "INFO",
 254                                _("The printer is not connected."));
 255           offline = 1;
 256         }
 257         else if (errno == EINTR && total_bytes == 0)
 258         {
 259           fputs("DEBUG: Received an interrupt before any bytes were "
 260                 "written, aborting.\n", stderr);
 261           return (0);
 262         }
 263
 264         sleep(1);
 265         continue;
 266       }
 267     }
 268
 269    /*
 270     * Check if we have a side-channel request ready...
 271     */
 272
 273     if (side_cb && FD_ISSET(CUPS_SC_FD, &input))
 274     {
 275      /*
 276       * Do the side-channel request, then start back over in the select
 277       * loop since it may have read from print_fd...
 278       */
 279
 280       if ((*side_cb)(print_fd, device_fd, snmp_fd, addr, use_bc))
 281         side_cb = NULL;
 282       continue;
 283     }
 284
 285    /*
 286     * Check if we have back-channel data ready...
 287     */
 288
 289     if (FD_ISSET(device_fd, &input))
 290     {
 291       if ((bc_bytes = read(device_fd, bc_buffer, sizeof(bc_buffer))) > 0)
 292       {
 293         fprintf(stderr,
 294                 "DEBUG: Received " CUPS_LLFMT " bytes of back-channel data\n",
 295                 CUPS_LLCAST bc_bytes);
 296         cupsBackChannelWrite(bc_buffer, bc_bytes, 1.0);
 297       }
 298       else if (bc_bytes < 0 && errno != EAGAIN && errno != EINTR)
 299       {
 300         fprintf(stderr, "DEBUG: Error reading back-channel data: %s\n",
 301                 strerror(errno));
 302         use_bc = 0;
 303       }
 304       else if (bc_bytes == 0)
 305         use_bc = 0;
 306     }
 307
 308    /*
 309     * Check if we have print data ready...
 310     */
 311
 312     if (FD_ISSET(print_fd, &input))
 313     {
 314       if ((print_bytes = read(print_fd, print_buffer,
 315                               sizeof(print_buffer))) < 0)
 316       {
 317        /*
 318         * Read error - bail if we don't see EAGAIN or EINTR...
 319         */
 320
 321         if (errno != EAGAIN || errno != EINTR)
 322         {
 323           fprintf(stderr, "DEBUG: Read failed: %s\n", strerror(errno));
 324           _cupsLangPrintFilter(stderr, "ERROR",
 325                                _("Unable to read print data."));
 326           return (-1);
 327         }
 328
 329         print_bytes = 0;
 330       }
 331       else if (print_bytes == 0)
 332       {
 333        /*
 334         * End of file, break out of the loop...
 335         */
 336
 337         break;
 338       }
 339
 340       print_ptr = print_buffer;
 341
 342       fprintf(stderr, "DEBUG: Read %d bytes of print data...\n",
 343               (int)print_bytes);
 344     }
 345
 346    /*
 347     * Check if the device is ready to receive data and we have data to
 348     * send...
 349     */
 350
 351     if (print_bytes && FD_ISSET(device_fd, &output))
 352     {
 353       if ((bytes = write(device_fd, print_ptr, print_bytes)) < 0)
 354       {
 355        /*
 356         * Write error - bail if we don't see an error we can retry...
 357         */
 358
 359         if (errno == ENOSPC)
 360         {
 361           if (paperout != 1 && update_state)
 362           {
 363             fputs("STATE: +media-empty-warning\n", stderr);
 364             fputs("DEBUG: Out of paper\n", stderr);
 365             paperout = 1;
 366           }
 367         }
 368         else if (errno == ENXIO)
 369         {
 370           if (offline != 1 && update_state)
 371           {
 372             fputs("STATE: +offline-report\n", stderr);
 373             _cupsLangPrintFilter(stderr, "INFO",
 374                                  _("The printer is not connected."));
 375             offline = 1;
 376           }
 377         }
 378         else if (errno != EAGAIN && errno != EINTR && errno != ENOTTY)
 379         {
 380           _cupsLangPrintError("ERROR", _("Unable to write print data"));
 381           return (-1);
 382         }
 383       }
 384       else
 385       {
 386         if (paperout && update_state)
 387         {
 388           fputs("STATE: -media-empty-warning\n", stderr);
 389           paperout = 0;
 390         }
 391
 392         if (offline && update_state)
 393         {
 394           fputs("STATE: -offline-report\n", stderr);
 395           _cupsLangPrintFilter(stderr, "INFO",
 396                                _("The printer is now connected."));
 397           offline = 0;
 398         }
 399
 400         fprintf(stderr, "DEBUG: Wrote %d bytes of print data...\n", (int)bytes);
 401
 402         print_bytes -= bytes;
 403         print_ptr   += bytes;
 404         total_bytes += bytes;
 405       }
 406     }
 407
 408    /*
 409     * Do SNMP updates periodically...
 410     */
 411
 412     if (snmp_fd >= 0 && time(&curtime) >= snmp_update)
 413     {
 414       if (backendSNMPSupplies(snmp_fd, addr, NULL, NULL))
 415         snmp_update = INT_MAX;
 416       else
 417         snmp_update = curtime + 5;
 418     }
 419   }
 420
 421  /*
 422   * Return with success...
 423   */
 424
 425   return (total_bytes);
 426 }
 427
 428
 429 /*
 430  * 'backendWaitLoop()' - Wait for input from stdin while handling side-channel
 431  *                       queries.
 432  */
 433
 434 int                                     /* O - 1 if data is ready, 0 if not */
 435 backendWaitLoop(
 436     int          snmp_fd,               /* I - SNMP socket or -1 if none */
 437     http_addr_t  *addr,                 /* I - Address of device */
 438     int          use_bc,                /* I - Use back-channel? */
 439     _cups_sccb_t side_cb)               /* I - Side-channel callback */
 440 {
 441   int                   nfds;           /* Number of file descriptors */
 442   fd_set                input;          /* Input set for reading */
 443   time_t                curtime = 0,    /* Current time */
 444                         snmp_update = 0;/* Last SNMP status update */
 445   struct timeval        timeout;        /* Timeout for select() */
 446
 447
 448   fprintf(stderr, "DEBUG: backendWaitLoop(snmp_fd=%d, addr=%p, side_cb=%p)\n",
 449           snmp_fd, addr, side_cb);
 450
 451  /*
 452   * Now loop until we receive data from stdin...
 453   */
 454
 455   if (snmp_fd >= 0)
 456     snmp_update = time(NULL) + 5;
 457
 458   for (;;)
 459   {
 460    /*
 461     * Use select() to determine whether we have data to copy around...
 462     */
 463
 464     FD_ZERO(&input);
 465     FD_SET(0, &input);
 466     if (side_cb)
 467       FD_SET(CUPS_SC_FD, &input);
 468
 469     if (snmp_fd >= 0)
 470     {
 471       curtime         = time(NULL);
 472       timeout.tv_sec  = curtime >= snmp_update ? 0 : snmp_update - curtime;
 473       timeout.tv_usec = 0;
 474
 475       nfds = select(CUPS_SC_FD + 1, &input, NULL, NULL, &timeout);
 476     }
 477     else
 478       nfds = select(CUPS_SC_FD + 1, &input, NULL, NULL, NULL);
 479
 480     if (nfds < 0)
 481     {
 482      /*
 483       * Pause printing to clear any pending errors...
 484       */
 485
 486       if (errno == EINTR)
 487       {
 488         fputs("DEBUG: Received an interrupt before any bytes were "
 489               "written, aborting.\n", stderr);
 490         return (0);
 491       }
 492
 493       sleep(1);
 494       continue;
 495     }
 496
 497    /*
 498     * Check for input on stdin...
 499     */
 500
 501     if (FD_ISSET(0, &input))
 502       break;
 503
 504    /*
 505     * Check if we have a side-channel request ready...
 506     */
 507
 508     if (side_cb && FD_ISSET(CUPS_SC_FD, &input))
 509     {
 510      /*
 511       * Do the side-channel request, then start back over in the select
 512       * loop since it may have read from print_fd...
 513       */
 514
 515       if ((*side_cb)(0, -1, snmp_fd, addr, use_bc))
 516         side_cb = NULL;
 517       continue;
 518     }
 519
 520    /*
 521     * Do SNMP updates periodically...
 522     */
 523
 524     if (snmp_fd >= 0 && curtime >= snmp_update)
 525     {
 526       if (backendSNMPSupplies(snmp_fd, addr, NULL, NULL))
 527         snmp_fd = -1;
 528       else
 529         snmp_update = curtime + 5;
 530     }
 531   }
 532
 533  /*
 534   * Return with success...
 535   */
 536
 537   return (1);
 538 }
 539
 540
 541 /*
 542  * End of "$Id$".
 543  */