pbx_spool.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2010, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Full-featured outgoing call spool support
 * 
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 355058 $")

#include <sys/stat.h>
#include <time.h>
#include <utime.h>
#include <dirent.h>
#ifdef HAVE_INOTIFY
#include <sys/inotify.h>
#elif defined(HAVE_KQUEUE)
#include <sys/types.h>
#include <sys/time.h>
#include <sys/event.h>
#include <fcntl.h>
#endif

#include "asterisk/paths.h"   /* use ast_config_AST_SPOOL_DIR */
#include "asterisk/lock.h"
#include "asterisk/file.h"
#include "asterisk/logger.h"
#include "asterisk/channel.h"
#include "asterisk/callerid.h"
#include "asterisk/pbx.h"
#include "asterisk/module.h"
#include "asterisk/utils.h"
#include "asterisk/options.h"

/*
 * pbx_spool is similar in spirit to qcall, but with substantially enhanced functionality...
 * The spool file contains a header 
 */

enum {
   /*! Always delete the call file after a call succeeds or the
    * maximum number of retries is exceeded, even if the
    * modification time of the call file is in the future.
    */
   SPOOL_FLAG_ALWAYS_DELETE = (1 << 0),
   /* Don't unlink the call file after processing, move in qdonedir */
   SPOOL_FLAG_ARCHIVE = (1 << 1),
};

static char qdir[255];
static char qdonedir[255];

struct outgoing {
   int retries;                              /*!< Current number of retries */
   int maxretries;                           /*!< Maximum number of retries permitted */
   int retrytime;                            /*!< How long to wait between retries (in seconds) */
   int waittime;                             /*!< How long to wait for an answer */
   long callingpid;                          /*!< PID which is currently calling */
   struct ast_format_cap *capabilities;                 /*!< Formats (codecs) for this call */
   AST_DECLARE_STRING_FIELDS (
      AST_STRING_FIELD(fn);                 /*!< File name of call file */
      AST_STRING_FIELD(tech);               /*!< Which channel technology to use for outgoing call */
      AST_STRING_FIELD(dest);               /*!< Which device/line to use for outgoing call */
      AST_STRING_FIELD(app);                /*!< If application: Application name */
      AST_STRING_FIELD(data);               /*!< If application: Application data */
      AST_STRING_FIELD(exten);              /*!< If extension/context/priority: Extension in dialplan */
      AST_STRING_FIELD(context);            /*!< If extension/context/priority: Dialplan context */
      AST_STRING_FIELD(cid_num);            /*!< CallerID Information: Number/extension */
      AST_STRING_FIELD(cid_name);           /*!< CallerID Information: Name */
      AST_STRING_FIELD(account);            /*!< account code */
   );
   int priority;                             /*!< If extension/context/priority: Dialplan priority */
   struct ast_variable *vars;                /*!< Variables and Functions */
   int maxlen;                               /*!< Maximum length of call */
   struct ast_flags options;                 /*!< options */
};

#if defined(HAVE_INOTIFY) || defined(HAVE_KQUEUE)
static void queue_file(const char *filename, time_t when);
#endif

static int init_outgoing(struct outgoing *o)
{
   struct ast_format tmpfmt;
   o->priority = 1;
   o->retrytime = 300;
   o->waittime = 45;

   if (!(o->capabilities = ast_format_cap_alloc_nolock())) {
      return -1;
   }
   ast_format_cap_add(o->capabilities, ast_format_set(&tmpfmt, AST_FORMAT_SLINEAR, 0));

   ast_set_flag(&o->options, SPOOL_FLAG_ALWAYS_DELETE);
   if (ast_string_field_init(o, 128)) {
      return -1;
   }
   return 0;
}

static void free_outgoing(struct outgoing *o)
{
   if (o->vars) {
      ast_variables_destroy(o->vars);
   }
   ast_string_field_free_memory(o);
   o->capabilities = ast_format_cap_destroy(o->capabilities);
   ast_free(o);
}

static int apply_outgoing(struct outgoing *o, const char *fn, FILE *f)
{
   char buf[256];
   char *c, *c2;
   int lineno = 0;
   struct ast_variable *var, *last = o->vars;

   while (last && last->next) {
      last = last->next;
   }

   while(fgets(buf, sizeof(buf), f)) {
      lineno++;
      /* Trim comments */
      c = buf;
      while ((c = strchr(c, '#'))) {
         if ((c == buf) || (*(c-1) == ' ') || (*(c-1) == '\t'))
            *c = '\0';
         else
            c++;
      }

      c = buf;
      while ((c = strchr(c, ';'))) {
         if ((c > buf) && (c[-1] == '\\')) {
            memmove(c - 1, c, strlen(c) + 1);
            c++;
         } else {
            *c = '\0';
            break;
         }
      }

      /* Trim trailing white space */
      while(!ast_strlen_zero(buf) && buf[strlen(buf) - 1] < 33)
         buf[strlen(buf) - 1] = '\0';
      if (!ast_strlen_zero(buf)) {
         c = strchr(buf, ':');
         if (c) {
            *c = '\0';
            c++;
            while ((*c) && (*c < 33))
               c++;
#if 0
            printf("'%s' is '%s' at line %d\n", buf, c, lineno);
#endif
            if (!strcasecmp(buf, "channel")) {
               if ((c2 = strchr(c, '/'))) {
                  *c2 = '\0';
                  c2++;
                  ast_string_field_set(o, tech, c);
                  ast_string_field_set(o, dest, c2);
               } else {
                  ast_log(LOG_NOTICE, "Channel should be in form Tech/Dest at line %d of %s\n", lineno, fn);
               }
            } else if (!strcasecmp(buf, "callerid")) {
               char cid_name[80] = {0}, cid_num[80] = {0};
               ast_callerid_split(c, cid_name, sizeof(cid_name), cid_num, sizeof(cid_num));
               ast_string_field_set(o, cid_num, cid_num);
               ast_string_field_set(o, cid_name, cid_name);
            } else if (!strcasecmp(buf, "application")) {
               ast_string_field_set(o, app, c);
            } else if (!strcasecmp(buf, "data")) {
               ast_string_field_set(o, data, c);
            } else if (!strcasecmp(buf, "maxretries")) {
               if (sscanf(c, "%30d", &o->maxretries) != 1) {
                  ast_log(LOG_WARNING, "Invalid max retries at line %d of %s\n", lineno, fn);
                  o->maxretries = 0;
               }
            } else if (!strcasecmp(buf, "codecs")) {
               ast_parse_allow_disallow(NULL, o->capabilities, c, 1);
            } else if (!strcasecmp(buf, "context")) {
               ast_string_field_set(o, context, c);
            } else if (!strcasecmp(buf, "extension")) {
               ast_string_field_set(o, exten, c);
            } else if (!strcasecmp(buf, "priority")) {
               if ((sscanf(c, "%30d", &o->priority) != 1) || (o->priority < 1)) {
                  ast_log(LOG_WARNING, "Invalid priority at line %d of %s\n", lineno, fn);
                  o->priority = 1;
               }
            } else if (!strcasecmp(buf, "retrytime")) {
               if ((sscanf(c, "%30d", &o->retrytime) != 1) || (o->retrytime < 1)) {
                  ast_log(LOG_WARNING, "Invalid retrytime at line %d of %s\n", lineno, fn);
                  o->retrytime = 300;
               }
            } else if (!strcasecmp(buf, "waittime")) {
               if ((sscanf(c, "%30d", &o->waittime) != 1) || (o->waittime < 1)) {
                  ast_log(LOG_WARNING, "Invalid waittime at line %d of %s\n", lineno, fn);
                  o->waittime = 45;
               }
            } else if (!strcasecmp(buf, "retry")) {
               o->retries++;
            } else if (!strcasecmp(buf, "startretry")) {
               if (sscanf(c, "%30ld", &o->callingpid) != 1) {
                  ast_log(LOG_WARNING, "Unable to retrieve calling PID!\n");
                  o->callingpid = 0;
               }
            } else if (!strcasecmp(buf, "endretry") || !strcasecmp(buf, "abortretry")) {
               o->callingpid = 0;
               o->retries++;
            } else if (!strcasecmp(buf, "delayedretry")) {
            } else if (!strcasecmp(buf, "setvar") || !strcasecmp(buf, "set")) {
               c2 = c;
               strsep(&c2, "=");
               if (c2) {
                  var = ast_variable_new(c, c2, fn);
                  if (var) {
                     /* Always insert at the end, because some people want to treat the spool file as a script */
                     if (last) {
                        last->next = var;
                     } else {
                        o->vars = var;
                     }
                     last = var;
                  }
               } else
                  ast_log(LOG_WARNING, "Malformed \"%s\" argument.  Should be \"%s: variable=value\"\n", buf, buf);
            } else if (!strcasecmp(buf, "account")) {
               ast_string_field_set(o, account, c);
            } else if (!strcasecmp(buf, "alwaysdelete")) {
               ast_set2_flag(&o->options, ast_true(c), SPOOL_FLAG_ALWAYS_DELETE);
            } else if (!strcasecmp(buf, "archive")) {
               ast_set2_flag(&o->options, ast_true(c), SPOOL_FLAG_ARCHIVE);
            } else {
               ast_log(LOG_WARNING, "Unknown keyword '%s' at line %d of %s\n", buf, lineno, fn);
            }
         } else
            ast_log(LOG_NOTICE, "Syntax error at line %d of %s\n", lineno, fn);
      }
   }
   ast_string_field_set(o, fn, fn);
   if (ast_strlen_zero(o->tech) || ast_strlen_zero(o->dest) || (ast_strlen_zero(o->app) && ast_strlen_zero(o->exten))) {
      ast_log(LOG_WARNING, "At least one of app or extension must be specified, along with tech and dest in file %s\n", fn);
      return -1;
   }
   return 0;
}

static void safe_append(struct outgoing *o, time_t now, char *s)
{
   FILE *f;
   struct utimbuf tbuf = { .actime = now, .modtime = now + o->retrytime };

   ast_debug(1, "Outgoing %s/%s: %s\n", o->tech, o->dest, s);

   if ((f = fopen(o->fn, "a"))) {
      fprintf(f, "\n%s: %ld %d (%ld)\n", s, (long)ast_mainpid, o->retries, (long) now);
      fclose(f);
   }

   /* Update the file time */
   if (utime(o->fn, &tbuf)) {
      ast_log(LOG_WARNING, "Unable to set utime on %s: %s\n", o->fn, strerror(errno));
   }
}

/*!
 * \brief Remove a call file from the outgoing queue optionally moving it in the archive dir
 *
 * \param o the pointer to outgoing struct
 * \param status the exit status of the call. Can be "Completed", "Failed" or "Expired"
 */
static int remove_from_queue(struct outgoing *o, const char *status)
{
   FILE *f;
   char newfn[256];
   const char *bname;

   if (!ast_test_flag(&o->options, SPOOL_FLAG_ALWAYS_DELETE)) {
      struct stat current_file_status;

      if (!stat(o->fn, &current_file_status)) {
         if (time(NULL) < current_file_status.st_mtime) {
            return 0;
         }
      }
   }

   if (!ast_test_flag(&o->options, SPOOL_FLAG_ARCHIVE)) {
      unlink(o->fn);
      return 0;
   }

   if (ast_mkdir(qdonedir, 0777)) {
      ast_log(LOG_WARNING, "Unable to create queue directory %s -- outgoing spool archiving disabled\n", qdonedir);
      unlink(o->fn);
      return -1;
   }

   if (!(bname = strrchr(o->fn, '/'))) {
      bname = o->fn;
   } else {
      bname++;
   }

   snprintf(newfn, sizeof(newfn), "%s/%s", qdonedir, bname);
   /* a existing call file the archive dir is overwritten */
   unlink(newfn);
   if (rename(o->fn, newfn) != 0) {
      unlink(o->fn);
      return -1;
   }

   /* Only append to the file AFTER we move it out of the watched directory,
    * otherwise the fclose() causes another event for inotify(7) */
   if ((f = fopen(newfn, "a"))) {
      fprintf(f, "Status: %s\n", status);
      fclose(f);
   }

   return 0;
}

static void *attempt_thread(void *data)
{
   struct outgoing *o = data;
   int res, reason;
   if (!ast_strlen_zero(o->app)) {
      ast_verb(3, "Attempting call on %s/%s for application %s(%s) (Retry %d)\n", o->tech, o->dest, o->app, o->data, o->retries);
      res = ast_pbx_outgoing_app(o->tech, o->capabilities, o->dest, o->waittime * 1000,
         o->app, o->data, &reason, 2 /* wait to finish */, o->cid_num, o->cid_name,
         o->vars, o->account, NULL);
      o->vars = NULL;
   } else {
      ast_verb(3, "Attempting call on %s/%s for %s@%s:%d (Retry %d)\n", o->tech, o->dest, o->exten, o->context,o->priority, o->retries);
      res = ast_pbx_outgoing_exten(o->tech, o->capabilities, o->dest,
         o->waittime * 1000, o->context, o->exten, o->priority, &reason,
         2 /* wait to finish */, o->cid_num, o->cid_name, o->vars, o->account, NULL);
      o->vars = NULL;
   }
   if (res) {
      ast_log(LOG_NOTICE, "Call failed to go through, reason (%d) %s\n", reason, ast_channel_reason2str(reason));
      if (o->retries >= o->maxretries + 1) {
         /* Max retries exceeded */
         ast_log(LOG_NOTICE, "Queued call to %s/%s expired without completion after %d attempt%s\n", o->tech, o->dest, o->retries - 1, ((o->retries - 1) != 1) ? "s" : "");
         remove_from_queue(o, "Expired");
      } else {
         /* Notate that the call is still active */
         safe_append(o, time(NULL), "EndRetry");
#if defined(HAVE_INOTIFY) || defined(HAVE_KQUEUE)
         queue_file(o->fn, time(NULL) + o->retrytime);
#endif
      }
   } else {
      ast_log(LOG_NOTICE, "Call completed to %s/%s\n", o->tech, o->dest);
      remove_from_queue(o, "Completed");
   }
   free_outgoing(o);
   return NULL;
}

static void launch_service(struct outgoing *o)
{
   pthread_t t;
   int ret;

   if ((ret = ast_pthread_create_detached(&t, NULL, attempt_thread, o))) {
      ast_log(LOG_WARNING, "Unable to create thread :( (returned error: %d)\n", ret);
      free_outgoing(o);
   }
}

/* Called from scan_thread or queue_file */
static int scan_service(const char *fn, time_t now)
{
   struct outgoing *o = NULL;
   FILE *f;
   int res = 0;

   if (!(o = ast_calloc(1, sizeof(*o)))) {
      ast_log(LOG_WARNING, "Out of memory ;(\n");
      return -1;
   }

   if (init_outgoing(o)) {
      /* No need to call free_outgoing here since we know the failure
       * was to allocate string fields and no variables have been allocated
       * yet.
       */
      ast_free(o);
      return -1;
   }

   /* Attempt to open the file */
   if (!(f = fopen(fn, "r"))) {
      remove_from_queue(o, "Failed");
      free_outgoing(o);
#if !defined(HAVE_INOTIFY) && !defined(HAVE_KQUEUE)
      ast_log(LOG_WARNING, "Unable to open %s: %s, deleting\n", fn, strerror(errno));
#endif
      return -1;
   }

   /* Read in and verify the contents */
   if (apply_outgoing(o, fn, f)) {
      remove_from_queue(o, "Failed");
      free_outgoing(o);
      ast_log(LOG_WARNING, "Invalid file contents in %s, deleting\n", fn);
      fclose(f);
      return -1;
   }

#if 0
   printf("Filename: %s, Retries: %d, max: %d\n", fn, o->retries, o->maxretries);
#endif
   fclose(f);
   if (o->retries <= o->maxretries) {
      now += o->retrytime;
      if (o->callingpid && (o->callingpid == ast_mainpid)) {
         safe_append(o, time(NULL), "DelayedRetry");
         ast_debug(1, "Delaying retry since we're currently running '%s'\n", o->fn);
         free_outgoing(o);
      } else {
         /* Increment retries */
         o->retries++;
         /* If someone else was calling, they're presumably gone now
            so abort their retry and continue as we were... */
         if (o->callingpid)
            safe_append(o, time(NULL), "AbortRetry");

         safe_append(o, now, "StartRetry");
         launch_service(o);
      }
      res = now;
   } else {
      ast_log(LOG_NOTICE, "Queued call to %s/%s expired without completion after %d attempt%s\n", o->tech, o->dest, o->retries - 1, ((o->retries - 1) != 1) ? "s" : "");
      remove_from_queue(o, "Expired");
      free_outgoing(o);
   }

   return res;
}

#if defined(HAVE_INOTIFY) || defined(HAVE_KQUEUE)
struct direntry {
   AST_LIST_ENTRY(direntry) list;
   time_t mtime;
   char name[0];
};

static AST_LIST_HEAD_STATIC(dirlist, direntry);

#if defined(HAVE_INOTIFY)
/* Only one thread is accessing this list, so no lock is necessary */
static AST_LIST_HEAD_NOLOCK_STATIC(createlist, direntry);
static AST_LIST_HEAD_NOLOCK_STATIC(openlist, direntry);
#endif

static void queue_file(const char *filename, time_t when)
{
   struct stat st;
   struct direntry *cur, *new;
   int res;
   time_t now = time(NULL);

   if (filename[0] != '/') {
      char *fn = alloca(strlen(qdir) + strlen(filename) + 2);
      sprintf(fn, "%s/%s", qdir, filename); /* SAFE */
      filename = fn;
   }

   if (when == 0) {
      if (stat(filename, &st)) {
         ast_log(LOG_WARNING, "Unable to stat %s: %s\n", filename, strerror(errno));
         return;
      }

      if (!S_ISREG(st.st_mode)) {
         return;
      }

      when = st.st_mtime;
   }

   /* Need to check the existing list in order to avoid duplicates. */
   AST_LIST_LOCK(&dirlist);
   AST_LIST_TRAVERSE(&dirlist, cur, list) {
      if (cur->mtime == when && !strcmp(filename, cur->name)) {
         AST_LIST_UNLOCK(&dirlist);
         return;
      }
   }

   if ((res = when) > now || (res = scan_service(filename, now)) > 0) {
      if (!(new = ast_calloc(1, sizeof(*new) + strlen(filename) + 1))) {
         AST_LIST_UNLOCK(&dirlist);
         return;
      }
      new->mtime = res;
      strcpy(new->name, filename);
      /* List is ordered by mtime */
      if (AST_LIST_EMPTY(&dirlist)) {
         AST_LIST_INSERT_HEAD(&dirlist, new, list);
      } else {
         int found = 0;
         AST_LIST_TRAVERSE_SAFE_BEGIN(&dirlist, cur, list) {
            if (cur->mtime > new->mtime) {
               AST_LIST_INSERT_BEFORE_CURRENT(new, list);
               found = 1;
               break;
            }
         }
         AST_LIST_TRAVERSE_SAFE_END
         if (!found) {
            AST_LIST_INSERT_TAIL(&dirlist, new, list);
         }
      }
   }
   AST_LIST_UNLOCK(&dirlist);
}

#ifdef HAVE_INOTIFY
static void queue_file_create(const char *filename)
{
   struct direntry *cur;

   AST_LIST_TRAVERSE(&createlist, cur, list) {
      if (!strcmp(cur->name, filename)) {
         return;
      }
   }

   if (!(cur = ast_calloc(1, sizeof(*cur) + strlen(filename) + 1))) {
      return;
   }
   strcpy(cur->name, filename);
   /* We'll handle this file unless an IN_OPEN event occurs within 2 seconds */
   cur->mtime = time(NULL) + 2;
   AST_LIST_INSERT_TAIL(&createlist, cur, list);
}

static void queue_file_open(const char *filename)
{
   struct direntry *cur;

   AST_LIST_TRAVERSE_SAFE_BEGIN(&createlist, cur, list) {
      if (!strcmp(cur->name, filename)) {
         AST_LIST_REMOVE_CURRENT(list);
         AST_LIST_INSERT_TAIL(&openlist, cur, list);
         break;
      }
   }
   AST_LIST_TRAVERSE_SAFE_END
}

static void queue_created_files(void)
{
   struct direntry *cur;
   time_t now = time(NULL);

   AST_LIST_TRAVERSE_SAFE_BEGIN(&createlist, cur, list) {
      if (cur->mtime > now) {
         break;
      }

      AST_LIST_REMOVE_CURRENT(list);
      queue_file(cur->name, 0);
      ast_free(cur);
   }
   AST_LIST_TRAVERSE_SAFE_END
}

static void queue_file_write(const char *filename)
{
   struct direntry *cur;
   /* Only queue entries where an IN_CREATE preceded the IN_CLOSE_WRITE */
   AST_LIST_TRAVERSE_SAFE_BEGIN(&openlist, cur, list) {
      if (!strcmp(cur->name, filename)) {
         AST_LIST_REMOVE_CURRENT(list);
         ast_free(cur);
         queue_file(filename, 0);
         break;
      }
   }
   AST_LIST_TRAVERSE_SAFE_END
}
#endif

static void *scan_thread(void *unused)
{
   DIR *dir;
   struct dirent *de;
   time_t now;
   struct timespec ts = { .tv_sec = 1 };
#ifdef HAVE_INOTIFY
   ssize_t res;
   int inotify_fd = inotify_init();
   struct inotify_event *iev;
   char buf[8192] __attribute__((aligned (sizeof(int))));
   struct pollfd pfd = { .fd = inotify_fd, .events = POLLIN };
#else
   struct timespec nowait = { 0, 1 };
   int inotify_fd = kqueue();
   struct kevent kev;
#endif
   struct direntry *cur;

   while (!ast_fully_booted) {
      nanosleep(&ts, NULL);
   }

   if (inotify_fd < 0) {
      ast_log(LOG_ERROR, "Unable to initialize "
#ifdef HAVE_INOTIFY
         "inotify(7)"
#else
         "kqueue(2)"
#endif
         "\n");
      return NULL;
   }

#ifdef HAVE_INOTIFY
   inotify_add_watch(inotify_fd, qdir, IN_CREATE | IN_OPEN | IN_CLOSE_WRITE | IN_MOVED_TO);
#endif

   /* First, run through the directory and clear existing entries */
   if (!(dir = opendir(qdir))) {
      ast_log(LOG_ERROR, "Unable to open directory %s: %s\n", qdir, strerror(errno));
      return NULL;
   }

#ifndef HAVE_INOTIFY
   EV_SET(&kev, dirfd(dir), EVFILT_VNODE, EV_ADD | EV_ENABLE | EV_CLEAR, NOTE_WRITE, 0, NULL);
   if (kevent(inotify_fd, &kev, 1, NULL, 0, &nowait) < 0 && errno != 0) {
      ast_log(LOG_ERROR, "Unable to watch directory %s: %s\n", qdir, strerror(errno));
   }
#endif
   now = time(NULL);
   while ((de = readdir(dir))) {
      queue_file(de->d_name, 0);
   }

#ifdef HAVE_INOTIFY
   /* Directory needs to remain open for kqueue(2) */
   closedir(dir);
#endif

   /* Wait for either a) next timestamp to occur, or b) a change to happen */
   for (;/* ever */;) {
      time_t next = AST_LIST_EMPTY(&dirlist) ? INT_MAX : AST_LIST_FIRST(&dirlist)->mtime;

      time(&now);
      if (next > now) {
#ifdef HAVE_INOTIFY
         int stage = 0;
         /* Convert from seconds to milliseconds, unless there's nothing
          * in the queue already, in which case, we wait forever. */
         int waittime = next == INT_MAX ? -1 : (next - now) * 1000;
         if (!AST_LIST_EMPTY(&createlist)) {
            waittime = 1000;
         }
         /* When a file arrives, add it to the queue, in mtime order. */
         if ((res = poll(&pfd, 1, waittime)) > 0 && (stage = 1) &&
            (res = read(inotify_fd, &buf, sizeof(buf))) >= sizeof(*iev)) {
            ssize_t len = 0;
            /* File(s) added to directory, add them to my list */
            for (iev = (void *) buf; res >= sizeof(*iev); iev = (struct inotify_event *) (((char *) iev) + len)) {
               /* For an IN_MOVED_TO event, simply process the file. However, if
                * we get an IN_CREATE event it *might* be an open(O_CREAT) or it
                * might be a hardlink (like smsq does, since rename() might
                * overwrite an existing file). So we have to see if we get a
                * subsequent IN_OPEN event on the same file. If we do, keep it
                * on the openlist and wait for the corresponding IN_CLOSE_WRITE.
                * If we *don't* see an IN_OPEN event, then it was a hard link so
                * it can be processed immediately.
                *
                * Unfortunately, although open(O_CREAT) is an atomic file system
                * operation, the inotify subsystem doesn't give it to us in a
                * single event with both IN_CREATE|IN_OPEN set. It's two separate
                * events, and the kernel doesn't even give them to us at the same
                * time. We can read() from inotify_fd after the IN_CREATE event,
                * and get *nothing* from it. The IN_OPEN arrives only later! So
                * we have a very short timeout of 2 seconds. */
               if (iev->mask & IN_CREATE) {
                  queue_file_create(iev->name);
               } else if (iev->mask & IN_OPEN) {
                  queue_file_open(iev->name);
               } else if (iev->mask & IN_CLOSE_WRITE) {
                  queue_file_write(iev->name);
               } else if (iev->mask & IN_MOVED_TO) {
                  queue_file(iev->name, 0);
               } else {
                  ast_log(LOG_ERROR, "Unexpected event %d for file '%s'\n", (int) iev->mask, iev->name);
               }

               len = sizeof(*iev) + iev->len;
               res -= len;
            }
         } else if (res < 0 && errno != EINTR && errno != EAGAIN) {
            ast_debug(1, "Got an error back from %s(2): %s\n", stage ? "read" : "poll", strerror(errno));
         }
         time(&now);
      }
      queue_created_files();
#else
         struct timespec ts2 = { next - now, 0 };
         if (kevent(inotify_fd, NULL, 0, &kev, 1, &ts2) <= 0) {
            /* Interrupt or timeout, restart calculations */
            continue;
         } else {
            /* Directory changed, rescan */
            rewinddir(dir);
            while ((de = readdir(dir))) {
               queue_file(de->d_name, 0);
            }
         }
         time(&now);
      }
#endif

      /* Empty the list of all entries ready to be processed */
      AST_LIST_LOCK(&dirlist);
      while (!AST_LIST_EMPTY(&dirlist) && AST_LIST_FIRST(&dirlist)->mtime <= now) {
         cur = AST_LIST_REMOVE_HEAD(&dirlist, list);
         queue_file(cur->name, cur->mtime);
         ast_free(cur);
      }
      AST_LIST_UNLOCK(&dirlist);
   }
   return NULL;
}

#else
static void *scan_thread(void *unused)
{
   struct stat st;
   DIR *dir;
   struct dirent *de;
   char fn[256];
   int res;
   int force_poll = 1;
   time_t last = 0;
   time_t next = 0;
   time_t now;
   struct timespec ts = { .tv_sec = 1 };

   while (!ast_fully_booted) {
      nanosleep(&ts, NULL);
   }

   for (;;) {
      /* Wait a sec */
      nanosleep(&ts, NULL);
      time(&now);

      if (stat(qdir, &st)) {
         ast_log(LOG_WARNING, "Unable to stat %s\n", qdir);
         continue;
      }

      /* Make sure it is time for us to execute our check */
      if (!force_poll && st.st_mtime == last && (!next || now < next)) {
         /*
          * The directory timestamp did not change and any delayed
          * call-file is not ready to be executed.
          */
         continue;
      }

#if 0
      printf("atime: %ld, mtime: %ld, ctime: %ld\n", st.st_atime, st.st_mtime, st.st_ctime);
      printf("Ooh, something changed / timeout\n");
#endif

      if (!(dir = opendir(qdir))) {
         ast_log(LOG_WARNING, "Unable to open directory %s: %s\n", qdir, strerror(errno));
         continue;
      }

      /*
       * Since the dir timestamp is available at one second
       * resolution, we cannot know if it was updated within the same
       * second after we scanned it.  Therefore, we will force another
       * scan if the dir was just modified.
       */
      force_poll = (st.st_mtime == now);

      next = 0;
      last = st.st_mtime;
      while ((de = readdir(dir))) {
         snprintf(fn, sizeof(fn), "%s/%s", qdir, de->d_name);
         if (stat(fn, &st)) {
            ast_log(LOG_WARNING, "Unable to stat %s: %s\n", fn, strerror(errno));
            continue;
         }
         if (!S_ISREG(st.st_mode)) {
            /* Not a regular file. */
            continue;
         }
         if (st.st_mtime <= now) {
            res = scan_service(fn, now);
            if (res > 0) {
               /* The call-file is delayed or to be retried later. */
               if (!next || res < next) {
                  /* This delayed call file expires earlier. */
                  next = res;
               }
            } else if (res) {
               ast_log(LOG_WARNING, "Failed to scan service '%s'\n", fn);
            } else if (!next) {
               /* Expired entry: must recheck on the next go-around */
               next = st.st_mtime;
            }
         } else {
            /* The file's timestamp is in the future. */
            if (!next || st.st_mtime < next) {
               /* This call-file's timestamp expires earlier. */
               next = st.st_mtime;
            }
         }
      }
      closedir(dir);
   }
   return NULL;
}
#endif

static int unload_module(void)
{
   return -1;
}

static int load_module(void)
{
   pthread_t thread;
   int ret;
   snprintf(qdir, sizeof(qdir), "%s/%s", ast_config_AST_SPOOL_DIR, "outgoing");
   if (ast_mkdir(qdir, 0777)) {
      ast_log(LOG_WARNING, "Unable to create queue directory %s -- outgoing spool disabled\n", qdir);
      return AST_MODULE_LOAD_DECLINE;
   }
   snprintf(qdonedir, sizeof(qdir), "%s/%s", ast_config_AST_SPOOL_DIR, "outgoing_done");

   if ((ret = ast_pthread_create_detached_background(&thread, NULL, scan_thread, NULL))) {
      ast_log(LOG_WARNING, "Unable to create thread :( (returned error: %d)\n", ret);
      return AST_MODULE_LOAD_FAILURE;
   }

   return AST_MODULE_LOAD_SUCCESS;
}

AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Outgoing Spool Support");