From 96cfaf67a383cd3676a7dba61040e8c4b7a47b12 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stig=20Bj=C3=B8rlykke?= <stig@bjorlykke.org>
Date: Mon, 27 Sep 2021 13:10:43 +0200
Subject: [PATCH] Qt: Reload Lua FileHandler when having a capture file

Support reloading a Lua FileHandler when this is in use for a
loaded capture file. Prompt to save the file if having unsaved
changes because the file must be reloaded.

Fixes #17615
---
 debian/libwiretap0.symbols      |  1 +
 epan/wslua/wslua.h              |  1 +
 epan/wslua/wslua_file_handler.c | 12 +++++++++++-
 ui/qt/main_window_slots.cpp     | 25 ++++++++++++++++++++++++-
 wiretap/file_access.c           | 14 ++++++++++++++
 wiretap/wtap.h                  |  2 ++
 6 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/debian/libwiretap0.symbols b/debian/libwiretap0.symbols
index d2a133cc6f..218240f8ed 100644
--- a/debian/libwiretap0.symbols
+++ b/debian/libwiretap0.symbols
@@ -180,4 +180,5 @@ libwiretap.so.0 libwiretap0 #MINVER#
  wtap_snapshot_length@Base 1.9.1
  wtap_strerror@Base 1.9.1
  wtap_tsprec_string@Base 1.99.9
+ wtap_uses_lua_filehandler@Base 3.5.1
  wtap_write_shb_comment@Base 1.9.1
diff --git a/epan/wslua/wslua.h b/epan/wslua/wslua.h
index aab1c1c8e2..95c5eb559f 100644
--- a/epan/wslua/wslua.h
+++ b/epan/wslua/wslua.h
@@ -296,6 +296,7 @@ struct _wslua_filehandler {
     int write_close_ref;
     int file_type;
     gboolean registered;
+    gboolean removed; /* This is set during reload Lua plugins */
 };
 
 struct _wslua_dir {
diff --git a/epan/wslua/wslua_file_handler.c b/epan/wslua/wslua_file_handler.c
index 0e2b8f6e82..6ddfed8714 100644
--- a/epan/wslua/wslua_file_handler.c
+++ b/epan/wslua/wslua_file_handler.c
@@ -75,6 +75,9 @@ report_error(int *err, gchar **err_info, const char *fmt, ...)
         report_error(err, err_info, "Error in file %s: no Lua FileHandler object", #name); \
         return retval; \
     } \
+    if (fh->removed) { \
+        return retval; \
+    } \
     if (!fh->registered) { \
         report_error(err, err_info, "Error in file %s: Lua FileHandler is not registered", #name); \
         return retval; \
@@ -310,6 +313,11 @@ wslua_filehandler_seek_read(wtap *wth, gint64 seek_off,
     CaptureInfo *fc = NULL;
     FrameInfo *fi = NULL;
 
+    if (fh->removed) {
+        /* Return success when removed during reloading Lua plugins */
+        return TRUE;
+    }
+
     INIT_FILEHANDLER_ROUTINE(seek_read,FALSE,err,err_info);
 
     /* Reset errno */
@@ -1285,7 +1293,9 @@ int FileHandler_register(lua_State* L) {
 
 int wslua_deregister_filehandlers(lua_State* L _U_) {
     for (GSList *it = registered_file_handlers; it; it = it->next) {
-        wslua_deregister_filehandler_work((FileHandler)it->data);
+        FileHandler fh = (FileHandler)it->data;
+        wslua_deregister_filehandler_work(fh);
+        fh->removed = TRUE;
     }
     g_slist_free(registered_file_handlers);
     registered_file_handlers = NULL;
diff --git a/ui/qt/main_window_slots.cpp b/ui/qt/main_window_slots.cpp
index a6f313d94c..01009f53b9 100644
--- a/ui/qt/main_window_slots.cpp
+++ b/ui/qt/main_window_slots.cpp
@@ -1529,6 +1529,22 @@ void MainWindow::reloadLuaPlugins()
     if (wsApp->isReloadingLua())
         return;
 
+    gboolean uses_lua_filehandler = FALSE;
+
+    if (capture_file_.capFile()) {
+        // Check if the current capture file is opened with a Lua FileHandler
+        capture_file *cf = capture_file_.capFile();
+        uses_lua_filehandler = wtap_uses_lua_filehandler(cf->provider.wth);
+
+        if (uses_lua_filehandler && cf->unsaved_changes) {
+            // Prompt to save the file before reloading, in case the FileHandler has changed
+            QString before_what(tr(" before reloading Lua plugins"));
+            if (!testCaptureFileClose(before_what, Reload)) {
+                return;
+            }
+        }
+    }
+
     wsApp->setReloadingLua(true);
 
     wslua_reload_plugins(NULL, NULL);
@@ -1544,7 +1560,14 @@ void MainWindow::reloadLuaPlugins()
 
     prefs_apply_all();
     fieldsChanged();
-    redissectPackets();
+
+    if (uses_lua_filehandler) {
+        // Reload the file in case the FileHandler has changed
+        cf_reload(capture_file_.capFile());
+        proto_free_deregistered_fields();
+    } else {
+        redissectPackets();
+    }
 
     wsApp->setReloadingLua(false);
     SimpleDialog::displayQueuedMessages();
diff --git a/wiretap/file_access.c b/wiretap/file_access.c
index 896a3317f0..93c638f5ba 100644
--- a/wiretap/file_access.c
+++ b/wiretap/file_access.c
@@ -591,6 +591,20 @@ wtap_has_open_info(const gchar *name)
 	return FALSE;
 }
 
+gboolean
+wtap_uses_lua_filehandler(const wtap* wth)
+{
+	if (wth && wth->wslua_data != NULL) {
+		/*
+		 * Currently, wslua_data is set if and only if using a Lua
+		 * file handler.
+		 */
+		return TRUE;
+	}
+
+	return FALSE;
+}
+
 /*
  * Visual C++ on Win32 systems doesn't define these.  (Old UNIX systems don't
  * define them either.)
diff --git a/wiretap/wtap.h b/wiretap/wtap.h
index 2a59e7f6e0..dd23d31d20 100644
--- a/wiretap/wtap.h
+++ b/wiretap/wtap.h
@@ -2236,6 +2236,8 @@ void wtap_register_open_info(struct open_info *oi, const gboolean first_routine)
 WS_DLL_PUBLIC
 gboolean wtap_has_open_info(const gchar *name);
 WS_DLL_PUBLIC
+gboolean wtap_uses_lua_filehandler(const wtap* wth);
+WS_DLL_PUBLIC
 void wtap_deregister_open_info(const gchar *name);
 
 WS_DLL_PUBLIC