Revert "Move fill_in_local_interfaces to a thread."

Calling scan_local_interfaces ends up calling fork via extcap. Doing so
from a thread is ill-adivsed:

https://rachelbythebay.com/w/2014/08/16/forkenv/
http://www.linuxprogrammingblog.com/threads-and-fork-think-twice-before-using-them

This reverts commit 5b4894b7959f44e077f36194c490cbf402e1e659.

Revert "fix compilation without pcap." as well.
This reverts commit 51300b3c834a3877d567fb57ae78ec74ec8ba80d.

Change-Id: Ic80582b52398c44af73c6d74dbb3216c4d1b37fc
Reviewed-on: https://code.wireshark.org/review/24772
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot
Reviewed-by: Gerald Combs <gerald@wireshark.org>

6 files changed, 77 insertions, 68 deletions

diff --git a/ui/capture_globals.h b/ui/capture_globals.h
index e71f29ade4..916bd37516 100644
--- a/ui/capture_globals.h
+++ b/ui/capture_globals.h
@@ -5,7 +5,19 @@
  * By Gerald Combs <gerald@wireshark.org>
  * Copyright 1998 Gerald Combs
  *
- * SPDX-License-Identifier: GPL-2.0+
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
 #ifndef __CAPTURE_GLOBALS_H__
@@ -17,10 +29,7 @@
 extern "C" {
 #endif /* __cplusplus */
 
-// This should probably be behind an API.
 extern capture_options global_capture_opts;
-// Should this be an element of capture_options?
-extern GMutex global_capture_opts_mtx;
 
 #ifdef __cplusplus
 }
diff --git a/ui/commandline.c b/ui/commandline.c
index f891fef5d0..8d81c8d1a9 100644
--- a/ui/commandline.c
+++ b/ui/commandline.c
@@ -5,7 +5,19 @@
  * By Gerald Combs <gerald@wireshark.org>
  * Copyright 1998 Gerald Combs
  *
- * SPDX-License-Identifier: GPL-2.0+
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
 #include "config.h"
@@ -54,8 +66,6 @@ commandline_param_info_t global_commandline_info;
 
 #if defined(HAVE_LIBPCAP) || defined(HAVE_EXTCAP)
 capture_options global_capture_opts;
-// Initialized in fill_in_local_interfaces_start.
-GMutex global_capture_opts_mtx;
 #endif
 
 void
diff --git a/ui/gtk/main.c b/ui/gtk/main.c
index 2153a22a38..075f4995bf 100644
--- a/ui/gtk/main.c
+++ b/ui/gtk/main.c
@@ -2172,7 +2172,6 @@ main(int argc, char *argv[])
 
     capture_session_init(&global_capture_session, &cfile);
 #endif
-    fill_in_local_interfaces_start();
 
     init_report_message(vfailure_alert_box, vwarning_alert_box,
                         open_failure_alert_box, read_failure_alert_box,
@@ -2275,8 +2274,7 @@ main(int argc, char *argv[])
 #ifdef HAVE_LIBPCAP
     splash_update(RA_INTERFACES, NULL, (gpointer)splash_win);
 
-    fill_in_local_interfaces_wait(main_window_update);
-    g_mutex_lock(&global_capture_opts_mtx);
+    fill_in_local_interfaces(main_window_update);
 
     if  (global_commandline_info.list_link_layer_types)
         caps_queries |= CAPS_QUERY_LINK_TYPES;
@@ -2613,7 +2611,6 @@ main(int argc, char *argv[])
         if (!global_commandline_info.start_capture && !global_capture_opts.default_options.cfilter) {
             global_capture_opts.default_options.cfilter = g_strdup(get_conn_cfilter());
         }
-        g_mutex_unlock(&global_capture_opts_mtx);
 #else /* HAVE_LIBPCAP */
         show_main_window(FALSE);
         check_and_warn_user_startup(global_commandline_info.cf_name);
diff --git a/ui/gtk/main_welcome.c b/ui/gtk/main_welcome.c
index 972552671d..8ab92a6f4a 100644
--- a/ui/gtk/main_welcome.c
+++ b/ui/gtk/main_welcome.c
@@ -1276,6 +1276,7 @@ welcome_new(void)
     g_object_set_data(G_OBJECT(welcome_hb), CAPTURE_VIEW, topic_capture_to_fill);
 
 #ifdef HAVE_LIBPCAP
+    fill_in_local_interfaces(main_window_update);
     fill_capture_box();
 
     /* capture help topic */
diff --git a/ui/iface_lists.c b/ui/iface_lists.c
index 965bb3f45b..a1b66745f1 100644
--- a/ui/iface_lists.c
+++ b/ui/iface_lists.c
@@ -6,7 +6,19 @@
  * By Gerald Combs <gerald@wireshark.org>
  * Copyright 1998 Gerald Combs
  *
- * SPDX-License-Identifier: GPL-2.0+
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
 #include "config.h"
@@ -101,14 +113,18 @@ scan_local_interfaces(void (*update_cb)(void))
     GString           *ip_str;
     interface_options *interface_opts;
     gboolean          found = FALSE;
+    static gboolean   running = FALSE;
     GHashTable        *selected_devices;
 
-    /* scan_local_interfaces internally calls update_cb to process UI events
-       to avoid stuck UI while running possibly slow operations. A side effect
-       of this is that new interface changes can be detected before completing
-       the last one.
-       This return avoids recursive scan_local_interfaces operation. */
-    if (!g_mutex_trylock(&global_capture_opts_mtx)) return;
+    if (running) {
+        /* scan_local_interfaces internally calls update_cb to process UI events
+           to avoid stuck UI while running possibly slow operations. A side effect
+           of this is that new interface changes can be detected before completing
+           the last one.
+           This return avoids recursive scan_local_interfaces operation. */
+        return;
+    }
+    running = TRUE;
 
     /*
      * Clear list of known interfaces (all_ifaces) that will be re-discovered on
@@ -375,21 +391,16 @@ scan_local_interfaces(void (*update_cb)(void))
     }
 
     g_hash_table_destroy(selected_devices);
-    g_mutex_unlock(&global_capture_opts_mtx);
+    running = FALSE;
 }
 
-// XXX Copied from register.c
-#define CB_WAIT_TIME (150 * 1000) // microseconds
-static GThread *local_if_thread;
-static GAsyncQueue *local_interface_done_q;
-
 /*
  * Get the global interface list.  Generate it if we haven't done so
  * already.  This can be quite time consuming the first time, so
  * record how long it takes in the info log.
  */
-static void *
-fill_in_local_interfaces_worker(void *arg _U_)
+void
+fill_in_local_interfaces(void(*update_cb)(void))
 {
     GTimeVal start_time;
     GTimeVal end_time;
@@ -402,7 +413,7 @@ fill_in_local_interfaces_worker(void *arg _U_)
 
     if (!initialized) {
         /* do the actual work */
-        scan_local_interfaces(NULL);
+        scan_local_interfaces(update_cb);
         initialized = TRUE;
     }
     /* log how long it took */
@@ -411,34 +422,6 @@ fill_in_local_interfaces_worker(void *arg _U_)
                        ((end_time.tv_usec - start_time.tv_usec) / 1e6));
 
     g_log(LOG_DOMAIN_MAIN, G_LOG_LEVEL_INFO, "fill_in_local_interfaces() ends, taking %.3fs", elapsed);
-    g_async_queue_push(local_interface_done_q, GINT_TO_POINTER(TRUE));
-    return NULL;
-}
-#endif
-
-#if defined(HAVE_LIBPCAP) || defined(HAVE_EXTCAP)
-void
-fill_in_local_interfaces_start(void)
-{
-#ifdef HAVE_LIBPCAP
-    if (!local_interface_done_q) {
-        g_mutex_init(&global_capture_opts_mtx);
-        local_interface_done_q = g_async_queue_new();
-    }
-    local_if_thread = g_thread_new("fill_in_local_interfaces_worker", &fill_in_local_interfaces_worker, NULL);
-#endif
-}
-#endif
-
-#ifdef HAVE_LIBPCAP
-void
-fill_in_local_interfaces_wait(void(*update_cb)(void))
-{
-    while (!g_async_queue_timeout_pop(local_interface_done_q, CB_WAIT_TIME)) {
-        update_cb();
-    }
-    g_thread_join(local_if_thread);
-    local_if_thread = NULL;
 }
 
 void
diff --git a/ui/iface_lists.h b/ui/iface_lists.h
index a0cfe624df..0c40f02f17 100644
--- a/ui/iface_lists.h
+++ b/ui/iface_lists.h
@@ -2,7 +2,23 @@
  * Declarations of routines to manage the global list of interfaces and to
  * update widgets/windows displaying items from those lists
  *
- * SPDX-License-Identifier: GPL-2.0+
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
 #ifndef __IFACE_LISTS_H__
@@ -12,14 +28,6 @@
 extern "C" {
 #endif /* __cplusplus */
 
-#if defined(HAVE_LIBPCAP) || defined(HAVE_EXTCAP)
-/*
- * Update the global interface list in the background. Create it if we
- * haven't done so already.
- */
-extern void fill_in_local_interfaces_start(void);
-#endif
-
 #ifdef HAVE_LIBPCAP
 /*
  * Used when sorting an interface list into alphabetical order by
@@ -28,14 +36,15 @@ extern void fill_in_local_interfaces_start(void);
 extern gint if_list_comparator_alph(const void *first_arg, const void *second_arg);
 
 /*
- * Update the global interface list in the foreground.
+ * Get the global interface list.  Generate it if we haven't
+ * done so already.
  */
-extern void scan_local_interfaces(void (*update_cb)(void));
+extern void fill_in_local_interfaces(void(*update_cb)(void));
 
 /*
- * Wait for the global interface list creation to finish.
+ * Update the global interface list.
  */
-extern void fill_in_local_interfaces_wait(void(*update_cb)(void));
+extern void scan_local_interfaces(void (*update_cb)(void));
 
 /*
  * Hide the interfaces