scheduler/cups-deviced.c

/*
 * "$Id: cups-deviced.c 7011 2007-10-10 21:13:35Z mike $"
 *
 *   Device scanning mini-daemon for the Common UNIX Printing System (CUPS).
 *
 *   Copyright 2007 by Apple Inc.
 *   Copyright 1997-2006 by Easy Software Products.
 *
 *   These coded instructions, statements, and computer programs are the
 *   property of Apple Inc. and are protected by Federal copyright
 *   law.  Distribution and use rights are outlined in the file "LICENSE.txt"
 *   which should have been included with this file.  If this file is
 *   file is missing or damaged, see the license at "http://www.cups.org/".
 *
 * Contents:
 *
 *   main()            - Scan for devices and return an IPP response.
 *   add_dev()         - Add a new device to the list.
 *   compare_devs()    - Compare device names for sorting.
 *   run_backend()     - Run a backend to gather the available devices.
 *   sigalrm_handler() - Handle alarm signals for backends that get hung
 */

/*
 * Include necessary headers...
 */

#include "util.h"
#include <cups/array.h>
#include <cups/dir.h>
#include <fcntl.h>


/*
 * Device information structure...
 */

typedef struct
{
  char	device_class[128],		/* Device class */
	device_make_and_model[128],	/* Make and model, if known */
	device_info[128],		/* Device info/description */
	device_uri[1024],		/* Device URI */
	device_id[1024];		/* 1284 Device ID */
} dev_info_t;


/*
 * Local globals...
 */

static int		alarm_tripped;	/* Non-zero if alarm was tripped */
static cups_array_t	*devs;		/* Device info */
static int		normal_user;	/* Normal user ID */


/*
 * Local functions...
 */

static dev_info_t	*add_dev(const char *device_class,
			         const char *device_make_and_model,
				 const char *device_info,
				 const char *device_uri,
				 const char *device_id);
static int		compare_devs(dev_info_t *p0, dev_info_t *p1);
static FILE		*run_backend(const char *backend, int uid, int *pid);
static void		sigalrm_handler(int sig);


/*
 * 'main()' - Scan for devices and return an IPP response.
 *
 * Usage:
 *
 *    cups-deviced request_id limit options
 */

int					/* O - Exit code */
main(int  argc,				/* I - Number of command-line args */
     char *argv[])			/* I - Command-line arguments */
{
  const char	*server_bin;		/* CUPS_SERVERBIN environment variable */
  char		backends[1024];		/* Location of backends */
  int		request_id;		/* Request ID */
  int		count;			/* Number of devices from backend */
  int		compat;			/* Compatibility device? */
  FILE		*fp;			/* Pipe to device backend */
  int		pid;			/* Process ID of backend */
  cups_dir_t	*dir;			/* Directory pointer */
  cups_dentry_t *dent;			/* Directory entry */
  char		filename[1024],		/* Name of backend */
		line[2048],		/* Line from backend */
		dclass[64],		/* Device class */
		uri[1024],		/* Device URI */
		info[128],		/* Device info */
		make_model[256],	/* Make and model */
		device_id[1024];	/* 1284 device ID */
  int		num_options;		/* Number of options */
  cups_option_t	*options;		/* Options */
  const char	*requested;		/* requested-attributes option */
  int		send_class,		/* Send device-class attribute? */
		send_info,		/* Send device-info attribute? */
		send_make_and_model,	/* Send device-make-and-model attribute? */
		send_uri,		/* Send device-uri attribute? */
		send_id;		/* Send device-id attribute? */
  dev_info_t	*dev;			/* Current device */
#if defined(HAVE_SIGACTION) && !defined(HAVE_SIGSET)
  struct sigaction action;		/* Actions for POSIX signals */
#endif /* HAVE_SIGACTION && !HAVE_SIGSET */


  setbuf(stderr, NULL);

 /*
  * Check the command-line...
  */

  if (argc > 1)
    request_id = atoi(argv[1]);
  else
    request_id = 1;

  if (argc != 5)
  {
    fputs("Usage: cups-deviced request-id limit user-id options\n", stderr);

    return (1);
  }

  if (request_id < 1)
  {
    fprintf(stderr, "cups-deviced: Bad request ID %d!\n", request_id);

    return (1);
  }

  normal_user = atoi(argv[3]);
  if (normal_user <= 0)
  {
    fprintf(stderr, "cups-deviced: Bad user %d!\n", normal_user);

    return (1);
  }

  num_options = cupsParseOptions(argv[4], 0, &options);
  requested   = cupsGetOption("requested-attributes", num_options, options);

  if (!requested || strstr(requested, "all"))
  {
    send_class          = 1;
    send_info           = 1;
    send_make_and_model = 1;
    send_uri            = 1;
    send_id             = 1;
  }
  else
  {
    send_class          = strstr(requested, "device-class") != NULL;
    send_info           = strstr(requested, "device-info") != NULL;
    send_make_and_model = strstr(requested, "device-make-and-model") != NULL;
    send_uri            = strstr(requested, "device-uri") != NULL;
    send_id             = strstr(requested, "device-id") != NULL;
  }

 /*
  * Try opening the backend directory...
  */

  if ((server_bin = getenv("CUPS_SERVERBIN")) == NULL)
    server_bin = CUPS_SERVERBIN;

  snprintf(backends, sizeof(backends), "%s/backend", server_bin);

  if ((dir = cupsDirOpen(backends)) == NULL)
  {
    fprintf(stderr, "ERROR: [cups-deviced] Unable to open backend directory "
                    "\"%s\": %s", backends, strerror(errno));

    return (1);
  }

 /*
  * Setup the devices array...
  */

  devs = cupsArrayNew((cups_array_func_t)compare_devs, NULL);

 /*
  * Loop through all of the device backends...
  */

  while ((dent = cupsDirRead(dir)) != NULL)
  {
   /*
    * Skip entries that are not executable files...
    */

    if (!S_ISREG(dent->fileinfo.st_mode) ||
        (dent->fileinfo.st_mode & (S_IRUSR | S_IXUSR)) != (S_IRUSR | S_IXUSR))
      continue;

   /*
    * Change effective users depending on the backend permissions...
    */

    snprintf(filename, sizeof(filename), "%s/%s", backends, dent->filename);

   /*
    * Backends without permissions for normal users run as root,
    * all others run as the unprivileged user...
    */

    fp = run_backend(filename,
                     (dent->fileinfo.st_mode & (S_IRWXG | S_IRWXO))
		         ? normal_user : 0,
		     &pid);

   /*
    * Collect the output from the backend...
    */

    if (fp)
    {
     /*
      * Set an alarm for the first read from the backend; this avoids
      * problems when a backend is hung getting device information.
      */

#ifdef HAVE_SIGSET /* Use System V signals over POSIX to avoid bugs */
      sigset(SIGALRM, sigalrm_handler);
#elif defined(HAVE_SIGACTION)
      memset(&action, 0, sizeof(action));

      sigemptyset(&action.sa_mask);
      sigaddset(&action.sa_mask, SIGALRM);
      action.sa_handler = sigalrm_handler;
      sigaction(SIGALRM, &action, NULL);
#else
      signal(SIGALRM, sigalrm_handler);
#endif /* HAVE_SIGSET */

      alarm_tripped = 0;
      count         = 0;
      compat        = !strcmp(dent->filename, "smb");

      alarm(30);

      while (fgets(line, sizeof(line), fp) != NULL)
      {
       /*
        * Reset the alarm clock...
	*/

        alarm(30);

       /*
        * Each line is of the form:
	*
	*   class URI "make model" "name" ["1284 device ID"]
	*/

        device_id[0] = '\0';

        if (!strncasecmp(line, "Usage", 5))
	  compat = 1;
        else if (sscanf(line,
	                "%63s%1023s%*[ \t]\"%255[^\"]\"%*[ \t]\"%127[^\"]\""
			"%*[ \t]\"%1023[^\"]",
	                dclass, uri, make_model, info, device_id) < 4)
        {
	 /*
	  * Bad format; strip trailing newline and write an error message.
	  */

          if (line[strlen(line) - 1] == '\n')
	    line[strlen(line) - 1] = '\0';

	  fprintf(stderr, "ERROR: [cups-deviced] Bad line from \"%s\": %s\n",
	          dent->filename, line);
          compat = 1;
	  break;
        }
	else
	{
	 /*
	  * Add the device to the array of available devices...
	  */

          dev = add_dev(dclass, make_model, info, uri, device_id);
	  if (!dev)
	  {
            cupsDirClose(dir);
	    return (1);
	  }

          fprintf(stderr, "DEBUG: [cups-deviced] Added device \"%s\"...\n",
	          uri);
	  count ++;
	}
      }

     /*
      * Turn the alarm clock off and close the pipe to the command...
      */

      alarm(0);

      if (alarm_tripped)
        fprintf(stderr, "WARNING: [cups-deviced] Backend \"%s\" did not "
	                "respond within 30 seconds!\n", dent->filename);

      fclose(fp);
      kill(pid, SIGTERM);

     /*
      * Hack for backends that don't support the CUPS 1.1 calling convention:
      * add a network device with the method == backend name.
      */

      if (count == 0 && compat)
      {
	snprintf(line, sizeof(line), "Unknown Network Device (%s)",
	         dent->filename);

        dev = add_dev("network", line, "Unknown", dent->filename, "");
	if (!dev)
	{
          cupsDirClose(dir);
	  return (1);
	}

        fprintf(stderr, "DEBUG: [cups-deviced] Compatibility device "
	                "\"%s\"...\n", dent->filename);
      }
    }
    else
      fprintf(stderr, "WARNING: [cups-deviced] Unable to execute \"%s\" "
                      "backend: %s\n", dent->filename, strerror(errno));
  }

  cupsDirClose(dir);

 /*
  * Output the list of devices...
  */

  puts("Content-Type: application/ipp\n");

  cupsdSendIPPHeader(IPP_OK, request_id);
  cupsdSendIPPGroup(IPP_TAG_OPERATION);
  cupsdSendIPPString(IPP_TAG_CHARSET, "attributes-charset", "utf-8");
  cupsdSendIPPString(IPP_TAG_LANGUAGE, "attributes-natural-language", "en-US");

  if ((count = atoi(argv[2])) <= 0)
    count = cupsArrayCount(devs);

  if (count > cupsArrayCount(devs))
    count = cupsArrayCount(devs);

  for (dev = (dev_info_t *)cupsArrayFirst(devs);
       count > 0;
       count --, dev = (dev_info_t *)cupsArrayNext(devs))
  {
   /*
    * Add strings to attributes...
    */

    cupsdSendIPPGroup(IPP_TAG_PRINTER);
    if (send_class)
      cupsdSendIPPString(IPP_TAG_KEYWORD, "device-class", dev->device_class);
    if (send_info)
      cupsdSendIPPString(IPP_TAG_TEXT, "device-info", dev->device_info);
    if (send_make_and_model)
      cupsdSendIPPString(IPP_TAG_TEXT, "device-make-and-model",
                	 dev->device_make_and_model);
    if (send_uri)
      cupsdSendIPPString(IPP_TAG_URI, "device-uri", dev->device_uri);
    if (send_id)
      cupsdSendIPPString(IPP_TAG_TEXT, "device-id", dev->device_id);
  }

  cupsdSendIPPTrailer();

 /*
  * Free the devices array and return...
  */

  for (dev = (dev_info_t *)cupsArrayFirst(devs);
       dev;
       dev = (dev_info_t *)cupsArrayNext(devs))
    free(dev);

  cupsArrayDelete(devs);

  return (0);
}


/*
 * 'add_dev()' - Add a new device to the list.
 */

static dev_info_t *			/* O - New device or NULL on error */
add_dev(
    const char *device_class,		/* I - Device class */
    const char *device_make_and_model,	/* I - Device make and model */
    const char *device_info,		/* I - Device information */
    const char *device_uri,		/* I - Device URI */
    const char *device_id)		/* I - 1284 device ID */
{
  dev_info_t	*dev,			/* New device */
		*temp;			/* Found device */


 /*
  * Allocate memory for the device record...
  */

  if ((dev = calloc(1, sizeof(dev_info_t))) == NULL)
  {
    fputs("ERROR: [cups-deviced] Ran out of memory allocating a device!\n",
          stderr);
    return (NULL);
  }

 /*
  * Copy the strings over...
  */

  strlcpy(dev->device_class, device_class, sizeof(dev->device_class));
  strlcpy(dev->device_make_and_model, device_make_and_model,
          sizeof(dev->device_make_and_model));
  strlcpy(dev->device_info, device_info, sizeof(dev->device_info));
  strlcpy(dev->device_uri, device_uri, sizeof(dev->device_uri));
  strlcpy(dev->device_id, device_id, sizeof(dev->device_id));

 /*
  * Add the device to the array and return...
  */

  if ((temp = cupsArrayFind(devs, dev)) != NULL)
  {
   /*
    * Avoid duplicates!
    */

    free(dev);
    dev = temp;
  }
  else
    cupsArrayAdd(devs, dev);
    
  return (dev);
}


/*
 * 'compare_devs()' - Compare device names for sorting.
 */

static int				/* O - Result of comparison */
compare_devs(dev_info_t *d0,		/* I - First device */
             dev_info_t *d1)		/* I - Second device */
{
  int		diff;			/* Difference between strings */


 /*
  * Sort devices by device-info, device-class, and device-uri...
  */

  if ((diff = cupsdCompareNames(d0->device_info, d1->device_info)) != 0)
    return (diff);
  else if ((diff = strcasecmp(d0->device_class, d1->device_class)) != 0)
    return (diff);
  else
    return (strcasecmp(d0->device_uri, d1->device_uri));
}


/*
 * 'run_backend()' - Run a backend to gather the available devices.
 */

static FILE *				/* O - stdout of backend */
run_backend(const char *backend,	/* I - Backend to run */
            int        uid,		/* I - User ID to run as */
	    int        *pid)		/* O - Process ID of backend */
{
  int	fds[2];				/* Pipe file descriptors */


  if (pipe(fds))
  {
    fprintf(stderr, "ERROR: Unable to create a pipe for \"%s\" - %s\n",
            backend, strerror(errno));
    return (NULL);
  }

  if ((*pid = fork()) < 0)
  {
   /*
    * Error!
    */

    fprintf(stderr, "ERROR: Unable to fork for \"%s\" - %s\n", backend,
            strerror(errno));
    close(fds[0]);
    close(fds[1]);
    return (NULL);
  }
  else if (!*pid)
  {
   /*
    * Child comes here...
    */

    if (!getuid() && uid)
      setuid(uid);			/* Run as restricted user */

    close(0);				/* </dev/null */
    open("/dev/null", O_RDONLY);

    close(1);				/* >pipe */
    dup(fds[1]);

    close(fds[0]);			/* Close copies of pipes */
    close(fds[1]);

    execl(backend, backend, (char *)0);	/* Run it! */
    fprintf(stderr, "ERROR: Unable to execute \"%s\" - %s\n", backend,
            strerror(errno));
    exit(1);
  }

 /*
  * Parent comes here, make a FILE * from the input side of the pipe...
  */

  close(fds[1]);

  return (fdopen(fds[0], "r"));
}


/*
 * 'sigalrm_handler()' - Handle alarm signals for backends that get hung
 *                       trying to list the available devices...
 */

static void
sigalrm_handler(int sig)		/* I - Signal number */
{
  (void)sig; /* remove compiler warnings... */

  alarm_tripped = 1;
}


/*
 * End of "$Id: cups-deviced.c 7011 2007-10-10 21:13:35Z mike $".
 */