backend/runloop.c

   1 /*
   2  * "$Id: runloop.c 7895 2008-09-02 19:19:43Z mike $"
   3  *
   4  *   Common run loop APIs for CUPS.
   5  *
   6  *   Copyright 2007-2010 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  */
  22
  23 /*
  24  * Include necessary headers.
  25  */
  26
  27 #include "backend-private.h"
  28 #include <limits.h>
  29 #ifdef __hpux
  30 #  include <sys/time.h>
  31 #else
  32 #  include <sys/select.h>
  33 #endif /* __hpux */
  34
  35
  36 /*
  37  * 'backendDrainOutput()' - Drain pending print data to the device.
  38  */
  39
  40 int                                     /* O - 0 on success, -1 on error */
  41 backendDrainOutput(int print_fd,        /* I - Print file descriptor */
  42                    int device_fd)       /* I - Device file descriptor */
  43 {
  44   int           nfds;                   /* Maximum file descriptor value + 1 */
  45   fd_set        input;                  /* Input set for reading */
  46   ssize_t       print_bytes,            /* Print bytes read */
  47                 bytes;                  /* Bytes written */
  48   char          print_buffer[8192],     /* Print data buffer */
  49                 *print_ptr;             /* Pointer into print data buffer */
  50   struct timeval timeout;               /* Timeout for read... */
  51
  52
  53   fprintf(stderr, "DEBUG: backendDrainOutput(print_fd=%d, device_fd=%d)\n",
  54           print_fd, device_fd);
  55
  56  /*
  57   * Figure out the maximum file descriptor value to use with select()...
  58   */
  59
  60   nfds = (print_fd > device_fd ? print_fd : device_fd) + 1;
  61
  62  /*
  63   * Now loop until we are out of data from print_fd...
  64   */
  65
  66   for (;;)
  67   {
  68    /*
  69     * Use select() to determine whether we have data to copy around...
  70     */
  71
  72     FD_ZERO(&input);
  73     FD_SET(print_fd, &input);
  74
  75     timeout.tv_sec  = 0;
  76     timeout.tv_usec = 0;
  77
  78     if (select(nfds, &input, NULL, NULL, &timeout) < 0)
  79       return (-1);
  80
  81     if (!FD_ISSET(print_fd, &input))
  82       return (0);
  83
  84     if ((print_bytes = read(print_fd, print_buffer,
  85                             sizeof(print_buffer))) < 0)
  86     {
  87      /*
  88       * Read error - bail if we don't see EAGAIN or EINTR...
  89       */
  90
  91       if (errno != EAGAIN || errno != EINTR)
  92       {
  93         _cupsLangPrintError("ERROR", _("Unable to read print data"));
  94         return (-1);
  95       }
  96
  97       print_bytes = 0;
  98     }
  99     else if (print_bytes == 0)
 100     {
 101      /*
 102       * End of file, return...
 103       */
 104
 105       return (0);
 106     }
 107
 108     fprintf(stderr, "DEBUG: Read %d bytes of print data...\n",
 109             (int)print_bytes);
 110
 111     for (print_ptr = print_buffer; print_bytes > 0;)
 112     {
 113       if ((bytes = write(device_fd, print_ptr, print_bytes)) < 0)
 114       {
 115        /*
 116         * Write error - bail if we don't see an error we can retry...
 117         */
 118
 119         if (errno != ENOSPC && errno != ENXIO && errno != EAGAIN &&
 120             errno != EINTR && errno != ENOTTY)
 121         {
 122           _cupsLangPrintError("ERROR", _("Unable to write print data"));
 123           return (-1);
 124         }
 125       }
 126       else
 127       {
 128         fprintf(stderr, "DEBUG: Wrote %d bytes of print data...\n", (int)bytes);
 129
 130         print_bytes -= bytes;
 131         print_ptr   += bytes;
 132       }
 133     }
 134   }
 135 }
 136
 137
 138 /*
 139  * 'backendRunLoop()' - Read and write print and back-channel data.
 140  */
 141
 142 ssize_t                                 /* O - Total bytes on success, -1 on error */
 143 backendRunLoop(
 144     int         print_fd,               /* I - Print file descriptor */
 145     int         device_fd,              /* I - Device file descriptor */
 146     int         snmp_fd,                /* I - SNMP socket or -1 if none */
 147     http_addr_t *addr,                  /* I - Address of device */
 148     int         use_bc,                 /* I - Use back-channel? */
 149     int         update_state,           /* I - Update printer-state-reasons? */
 150     int         (*side_cb)(int, int, int, http_addr_t *, int))
 151                                         /* I - Side-channel callback */
 152 {
 153   int           nfds;                   /* Maximum file descriptor value + 1 */
 154   fd_set        input,                  /* Input set for reading */
 155                 output;                 /* Output set for writing */
 156   ssize_t       print_bytes,            /* Print bytes read */
 157                 bc_bytes,               /* Backchannel bytes read */
 158                 total_bytes,            /* Total bytes written */
 159                 bytes;                  /* Bytes written */
 160   int           paperout;               /* "Paper out" status */
 161   int           offline;                /* "Off-line" status */
 162   char          print_buffer[8192],     /* Print data buffer */
 163                 *print_ptr,             /* Pointer into print data buffer */
 164                 bc_buffer[1024];        /* Back-channel data buffer */
 165   struct timeval timeout;               /* Timeout for select() */
 166   time_t        curtime,                /* Current time */
 167                 snmp_update = 0;
 168 #if defined(HAVE_SIGACTION) && !defined(HAVE_SIGSET)
 169   struct sigaction action;              /* Actions for POSIX signals */
 170 #endif /* HAVE_SIGACTION && !HAVE_SIGSET */
 171
 172
 173   fprintf(stderr,
 174           "DEBUG: backendRunLoop(print_fd=%d, device_fd=%d, snmp_fd=%d, "
 175           "addr=%p, use_bc=%d, side_cb=%p)\n",
 176           print_fd, device_fd, snmp_fd, addr, use_bc, side_cb);
 177
 178  /*
 179   * If we are printing data from a print driver on stdin, ignore SIGTERM
 180   * so that the driver can finish out any page data, e.g. to eject the
 181   * current page.  We only do this for stdin printing as otherwise there
 182   * is no way to cancel a raw print job...
 183   */
 184
 185   if (!print_fd)
 186   {
 187 #ifdef HAVE_SIGSET /* Use System V signals over POSIX to avoid bugs */
 188     sigset(SIGTERM, SIG_IGN);
 189 #elif defined(HAVE_SIGACTION)
 190     memset(&action, 0, sizeof(action));
 191
 192     sigemptyset(&action.sa_mask);
 193     action.sa_handler = SIG_IGN;
 194     sigaction(SIGTERM, &action, NULL);
 195 #else
 196     signal(SIGTERM, SIG_IGN);
 197 #endif /* HAVE_SIGSET */
 198   }
 199   else if (print_fd < 0)
 200   {
 201    /*
 202     * Copy print data from stdin, but don't mess with the signal handlers...
 203     */
 204
 205     print_fd = 0;
 206   }
 207
 208  /*
 209   * Figure out the maximum file descriptor value to use with select()...
 210   */
 211
 212   nfds = (print_fd > device_fd ? print_fd : device_fd) + 1;
 213
 214  /*
 215   * Now loop until we are out of data from print_fd...
 216   */
 217
 218   for (print_bytes = 0, print_ptr = print_buffer, offline = -1,
 219            paperout = -1, total_bytes = 0;;)
 220   {
 221    /*
 222     * Use select() to determine whether we have data to copy around...
 223     */
 224
 225     FD_ZERO(&input);
 226     if (!print_bytes)
 227       FD_SET(print_fd, &input);
 228     if (use_bc)
 229       FD_SET(device_fd, &input);
 230     if (!print_bytes && side_cb)
 231       FD_SET(CUPS_SC_FD, &input);
 232
 233     FD_ZERO(&output);
 234     if (print_bytes || (!use_bc && !side_cb))
 235       FD_SET(device_fd, &output);
 236
 237     if (use_bc || side_cb)
 238     {
 239       timeout.tv_sec  = 5;
 240       timeout.tv_usec = 0;
 241
 242       if (select(nfds, &input, &output, NULL, &timeout) < 0)
 243       {
 244        /*
 245         * Pause printing to clear any pending errors...
 246         */
 247
 248         if (errno == ENXIO && offline != 1 && update_state)
 249         {
 250           fputs("STATE: +offline-report\n", stderr);
 251           _cupsLangPrintFilter(stderr, "INFO",
 252                                _("Printer is not currently connected."));
 253           offline = 1;
 254         }
 255         else if (errno == EINTR && total_bytes == 0)
 256         {
 257           fputs("DEBUG: Received an interrupt before any bytes were "
 258                 "written, aborting\n", stderr);
 259           return (0);
 260         }
 261
 262         sleep(1);
 263         continue;
 264       }
 265     }
 266
 267    /*
 268     * Check if we have a side-channel request ready...
 269     */
 270
 271     if (side_cb && FD_ISSET(CUPS_SC_FD, &input))
 272     {
 273      /*
 274       * Do the side-channel request, then start back over in the select
 275       * loop since it may have read from print_fd...
 276       */
 277
 278       if ((*side_cb)(print_fd, device_fd, snmp_fd, addr, use_bc))
 279         side_cb = NULL;
 280       continue;
 281     }
 282
 283    /*
 284     * Check if we have back-channel data ready...
 285     */
 286
 287     if (FD_ISSET(device_fd, &input))
 288     {
 289       if ((bc_bytes = read(device_fd, bc_buffer, sizeof(bc_buffer))) > 0)
 290       {
 291         fprintf(stderr,
 292                 "DEBUG: Received " CUPS_LLFMT " bytes of back-channel data\n",
 293                 CUPS_LLCAST bc_bytes);
 294         cupsBackChannelWrite(bc_buffer, bc_bytes, 1.0);
 295       }
 296       else if (bc_bytes < 0 && errno != EAGAIN && errno != EINTR)
 297       {
 298         fprintf(stderr, "DEBUG: Error reading back-channel data: %s\n",
 299                 strerror(errno));
 300         use_bc = 0;
 301       }
 302       else if (bc_bytes == 0)
 303         use_bc = 0;
 304     }
 305
 306    /*
 307     * Check if we have print data ready...
 308     */
 309
 310     if (FD_ISSET(print_fd, &input))
 311     {
 312       if ((print_bytes = read(print_fd, print_buffer,
 313                               sizeof(print_buffer))) < 0)
 314       {
 315        /*
 316         * Read error - bail if we don't see EAGAIN or EINTR...
 317         */
 318
 319         if (errno != EAGAIN || errno != EINTR)
 320         {
 321           _cupsLangPrintError("ERROR", _("Unable to read print data"));
 322           return (-1);
 323         }
 324
 325         print_bytes = 0;
 326       }
 327       else if (print_bytes == 0)
 328       {
 329        /*
 330         * End of file, break out of the loop...
 331         */
 332
 333         break;
 334       }
 335
 336       print_ptr = print_buffer;
 337
 338       fprintf(stderr, "DEBUG: Read %d bytes of print data...\n",
 339               (int)print_bytes);
 340     }
 341
 342    /*
 343     * Check if the device is ready to receive data and we have data to
 344     * send...
 345     */
 346
 347     if (print_bytes && FD_ISSET(device_fd, &output))
 348     {
 349       if ((bytes = write(device_fd, print_ptr, print_bytes)) < 0)
 350       {
 351        /*
 352         * Write error - bail if we don't see an error we can retry...
 353         */
 354
 355         if (errno == ENOSPC)
 356         {
 357           if (paperout != 1 && update_state)
 358           {
 359             fputs("STATE: +media-empty-warning\n", stderr);
 360             fputs("DEBUG: Out of paper\n", stderr);
 361             paperout = 1;
 362           }
 363         }
 364         else if (errno == ENXIO)
 365         {
 366           if (offline != 1 && update_state)
 367           {
 368             fputs("STATE: +offline-report\n", stderr);
 369             _cupsLangPrintFilter(stderr, "INFO",
 370                                  _("Printer is not currently connected."));
 371             offline = 1;
 372           }
 373         }
 374         else if (errno != EAGAIN && errno != EINTR && errno != ENOTTY)
 375         {
 376           _cupsLangPrintError("ERROR", _("Unable to write print data"));
 377           return (-1);
 378         }
 379       }
 380       else
 381       {
 382         if (paperout && update_state)
 383         {
 384           fputs("STATE: -media-empty-warning\n", stderr);
 385           paperout = 0;
 386         }
 387
 388         if (offline && update_state)
 389         {
 390           fputs("STATE: -offline-report\n", stderr);
 391           _cupsLangPrintFilter(stderr, "INFO", _("Printer is now connected."));
 392           offline = 0;
 393         }
 394
 395         fprintf(stderr, "DEBUG: Wrote %d bytes of print data...\n", (int)bytes);
 396
 397         print_bytes -= bytes;
 398         print_ptr   += bytes;
 399         total_bytes += bytes;
 400       }
 401     }
 402
 403    /*
 404     * Do SNMP updates periodically...
 405     */
 406
 407     if (snmp_fd >= 0 && time(&curtime) >= snmp_update)
 408     {
 409       if (backendSNMPSupplies(snmp_fd, addr, NULL, NULL))
 410         snmp_update = INT_MAX;
 411       else
 412         snmp_update = curtime + 5;
 413     }
 414   }
 415
 416  /*
 417   * Return with success...
 418   */
 419
 420   return (total_bytes);
 421 }
 422
 423
 424 /*
 425  * End of "$Id: runloop.c 7895 2008-09-02 19:19:43Z mike $".
 426  */