From c7f66cf93491fd3ed9ca03fe967a692d64546aa2 Mon Sep 17 00:00:00 2001
From: Gerald Combs <gerald@wireshark.org>
Date: Tue, 9 Feb 2021 15:48:08 -0800
Subject: [PATCH] TShark: Load extcap preferences only when needed.

In our first pass through our options, look for ones that might require
extcap. Call extcap_register_preferences() only when that's the case.

Warn about missing extcap preferences only when we've loaded them.
---
 epan/prefs.c | 12 ++++++++++--
 tshark.c     | 34 +++++++++++++++++++++++++++++++---
 2 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/epan/prefs.c b/epan/prefs.c
index c00491992e..6379db9fd5 100644
--- a/epan/prefs.c
+++ b/epan/prefs.c
@@ -5892,8 +5892,16 @@ set_pref(gchar *pref_name, const gchar *value, void *private_data _U_,
                 }
             }
         }
-        if (pref == NULL)
-            return PREFS_SET_NO_SUCH_PREF;        /* no such preference */
+        if (pref == NULL ) {
+            if (strcmp(module->name, "extcap") == 0 && g_list_length(module->prefs) <= 1) {
+                /*
+                 * Assume that we've skipped extcap preference registration
+                 * and that only extcap.gui_save_on_start is loaded.
+                 */
+                return PREFS_SET_OK;
+            }
+            return PREFS_SET_NO_SUCH_PREF;    /* no such preference */
+        }
 
         type = pref->type;
         if (IS_PREF_OBSOLETE(type)) {
diff --git a/tshark.c b/tshark.c
index 75acf90b48..00ef29f2c4 100644
--- a/tshark.c
+++ b/tshark.c
@@ -712,6 +712,7 @@ main(int argc, char *argv[])
     {0, 0, 0, 0 }
   };
   gboolean             arg_error = FALSE;
+  gboolean             has_extcap_options = FALSE;
 
   int                  err;
   gchar               *err_info;
@@ -835,6 +836,11 @@ main(int argc, char *argv[])
    * *after* epan_init() gets called, so that the dissectors have had a
    * chance to register their preferences.
    *
+   * Spawning a bunch of extcap processes can delay program startup,
+   * particularly on Windows. Check to see if we have any options that
+   * might require extcap and set has_extcap_options = TRUE if that's
+   * the case.
+   *
    * XXX - can we do this all with one getopt_long() call, saving the
    * arguments we can't handle until after initializing libwireshark,
    * and then process them after initializing libwireshark?
@@ -852,10 +858,26 @@ main(int argc, char *argv[])
         goto clean_exit;
       }
       break;
+    case 'G':
+      if (g_str_has_suffix(optarg, "prefs") || strcmp(optarg, "folders") == 0) {
+        has_extcap_options = TRUE;
+      }
+      break;
+    case 'i':
+      has_extcap_options = TRUE;
+      break;
+    case 'o':
+      if (g_str_has_prefix(optarg, "extcap.")) {
+        has_extcap_options = TRUE;
+      }
+      break;
     case 'P':        /* Print packet summary info even when writing to a file */
       print_packet_info = TRUE;
       print_summary = TRUE;
       break;
+    case 'r':        /* Read capture file x */
+      cf_name = g_strdup(optarg);
+      break;
     case 'O':        /* Only output these protocols */
       output_only = g_strdup(optarg);
       /* FALLTHROUGH */
@@ -940,7 +962,13 @@ main(int argc, char *argv[])
 
   register_all_tap_listeners(tap_reg_listener);
 
-  extcap_register_preferences();
+  /*
+   * An empty cf_name indicates that we're capturing, and we might
+   * be doing so on an extcap interface.
+   */
+  if (has_extcap_options || !cf_name) {
+    extcap_register_preferences();
+  }
 
   conversation_table_set_gui_info(init_iousers);
   hostlist_table_set_gui_info(init_hostlists);
@@ -1290,8 +1318,8 @@ main(int argc, char *argv[])
       quiet = TRUE;
       really_quiet = TRUE;
       break;
-    case 'r':        /* Read capture file x */
-      cf_name = g_strdup(optarg);
+    case 'r':
+      /* already processed; just ignore it now */
       break;
     case 'R':        /* Read file filter */
       rfilter = optarg;