count webcontrol as a thread to avoid a crash

On a SIGHUP restart the main thread waits to restart until all worker
threads are finished executing, except webcontrol wasn't included.
If it was still running (such as reading a web request), it would
have a dangling context pointer after cnt_list was freed leading to a
crash.  This counts that thread in the running threads, as a
termination webcontrol_finish variable to terminate it indepdent of
the device thread, and creates a webcontrol_running to identify when
it is running.

CHANGELOG

@@ -143,6 +143,7 @@ Bugfixes
    * Fixed leak in vloopback.
    * Fixed a build of motion for some kernel version with not good videodev.h 
    * Netcam Modulo 8
+   * Fix webhttpd race condition crash with SIGHUP, add it to running thread counter (David Fries)
 
 3.2.12 Summary of Changes
 

CREDITS

@@ -473,6 +473,9 @@ Mark Feenstra
 Miguel Freitas
    * Came up with the round robing idea.
 
+David Fries
+   * Fix webhttpd race condition crash with SIGHUP, add it to running thread counter
+
 Aaron Gage
    * Pointed me to the vid_mmap/int problem when calling SYNC in
      video.c

motion.c

@@ -341,6 +341,7 @@ static void sig_handler(int signo)
             while (cnt_list[++i]) {
                 cnt_list[i]->makemovie = 1;
                 cnt_list[i]->finish = 1;
+                cnt_list[i]->webcontrol_finish = 1;
                 /*
                  * Don't restart thread when it ends,
                  * all threads restarts if global restart is set
@@ -2723,8 +2724,21 @@ int main (int argc, char **argv)
          * Create a thread for the control interface if requested. Create it
          * detached and with 'motion_web_control' as the thread function.
          */
-        if (cnt_list[0]->conf.webcontrol_port)
-            pthread_create(&thread_id, &thread_attr, &motion_web_control, cnt_list);
+        if (cnt_list[0]->conf.webcontrol_port) {
+            pthread_mutex_lock(&global_lock);
+            threads_running++;
+            /* set outside the loop to avoid thread set vs main thread check */
+            cnt_list[0]->webcontrol_running = 1;
+            pthread_mutex_unlock(&global_lock);
+            if (pthread_create(&thread_id, &thread_attr, &motion_web_control,
+                cnt_list)) {
+                /* thread create failed, undo running state */
+                pthread_mutex_lock(&global_lock);
+                threads_running--;
+                cnt_list[0]->webcontrol_running = 0;
+                pthread_mutex_unlock(&global_lock);
+            }
+        }
 
         MOTION_LOG(NTC, TYPE_ALL, NO_ERRNO, "%s: Waiting for threads to finish, pid: %d",
                    getpid());
@@ -2746,6 +2760,9 @@ int main (int argc, char **argv)
                 if (cnt_list[i]->running || cnt_list[i]->restart)
                     motion_threads_running++;
             }
+            if (cnt_list[0]->conf.webcontrol_port &&
+                cnt_list[0]->webcontrol_running)
+                motion_threads_running++;
 
             if (((motion_threads_running == 0) && finish) ||
                 ((motion_threads_running == 0) && (threads_running == 0))) {
@@ -2805,7 +2822,7 @@ int main (int argc, char **argv)
 
 
     // Be sure that http control exits fine
-    cnt_list[0]->finish = 1;
+    cnt_list[0]->webcontrol_finish = 1;
     SLEEP(1, 0);
     MOTION_LOG(NTC, TYPE_ALL, NO_ERRNO, "%s: Motion terminating");
 

motion.h

@@ -370,6 +370,9 @@ struct context {
     volatile unsigned int restart;     /* Restart the thread when it ends */
     /* Is the motion thread running */
     volatile unsigned int running;
+    /* Is the web control thread running */
+    volatile unsigned int webcontrol_running;
+    volatile unsigned int webcontrol_finish;      /* End the thread */
     volatile int watchdog;
 
     pthread_t thread_id;

webhttpd.c

@@ -2515,7 +2515,7 @@ void httpd_run(struct context **cnt)
         client_socket_fd = acceptnonblocking(sd, NONBLOCK_TIMEOUT);
 
         if (client_socket_fd < 0) {
-            if ((!cnt[0]) || (cnt[0]->finish)) {
+            if ((!cnt[0]) || (cnt[0]->webcontrol_finish)) {
                 MOTION_LOG(NTC, TYPE_STREAM, NO_ERRNO, "%s: motion-httpd - Finishing");
                 closehttpd = 1;
             }
@@ -2545,6 +2545,17 @@ void *motion_web_control(void *arg)
 {
     struct context **cnt = arg;
     httpd_run(cnt);
+
+    /* 
+     * Update how many threads we have running. This is done within a
+     * mutex lock to prevent multiple simultaneous updates to
+     * 'threads_running'.
+     */
+    pthread_mutex_lock(&global_lock);
+    threads_running--;
+    cnt[0]->webcontrol_running = 0;
+    pthread_mutex_unlock(&global_lock);
+
     MOTION_LOG(NTC, TYPE_STREAM, NO_ERRNO, "%s: motion-httpd thread exit");
     pthread_exit(NULL);
 }