Lua: Switch from disable_lua to enable_lua.

Deprecate "disable_lua" in favor of "enable_lua". Configuration options
typically use "true" or a similar value to enable features. Using
"disable_lua = false" to enable Lua seems odd.

Change-Id: I224acad0559d409ea0a28b5555d1eb898564328c
Reviewed-on: https://code.wireshark.org/review/28773
Reviewed-by: Gerald Combs <gerald@wireshark.org>
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>

docbook/wsluarm.asciidoc

@@ -20,21 +20,23 @@ the Department of Computer Science.
 In Wireshark Lua can be used to write dissectors, taps, and capture file readers
 and writers.
 
-Wireshark’s Lua interpreter starts by loading `init.lua` that is located in the
-global configuration directory of Wireshark. Lua is enabled by default. To
-disable Lua the line variable _$$disable_lua$$_ should be set to _true_ in
-`init.lua`.
+Wireshark’s Lua interpreter starts by loading a file named `init.lua` in
+Wireshark's global configuration directory. It is enabled by default. To
+disable Lua the line variable _$$enable_lua$$_ should be set to _false_
+in _init.lua_. Wireshark 2.6 and earlier enabled and disabled Lua using
+the variable _$$disable_lua$$_. It is still supported, but is deprecated
+and support may be removed in a future release. _$$enable_lua$$_ takes
+precedence over _$$disable_lua$$_.
 
-After loading _init.lua_ from the data directory if Lua is enabled Wireshark
-will try to load a file named `init.lua` in the user’s directory.
-
-Wireshark will also load all files with `.lua` suffix from both the global and
-the personal plugins directory.
+If Lua is enabled Wireshark will then try to load a file named _init.lua_
+in the user’s personal configuration directory. Wireshark will also load
+all files with a _.lua_ suffix from both the global and the personal
+plugins directory.
 
 The command line option _$$-X lua_script:$$++file.lua++_ can be used to load
 Lua scripts as well.
 
-The Lua code will be executed once after all the protocol dissectors have being
+The Lua code will be executed once after all the protocol dissectors have been
 initialized and before reading any file.
 
 [[wslua_dissector_example]]

epan/wslua/init_wslua.c

@@ -767,6 +767,7 @@ wslua_allocf(void *ud _U_, void *ptr, size_t osize _U_, size_t nsize)
 void wslua_init(register_cb cb, gpointer client_data) {
     gchar* filename;
     const funnel_ops_t* ops = funnel_get_funnel_ops();
+    gboolean enable_lua = TRUE;
     gboolean run_anyway = FALSE;
     expert_module_t* expert_lua;
     int file_count = 1;
@@ -923,16 +924,25 @@ void wslua_init(register_cb cb, gpointer client_data) {
     filename = NULL;
 
     /* check if lua is to be disabled */
-    lua_getglobal(L,"disable_lua");
+    lua_getglobal(L, "disable_lua"); // 2.6 and earlier, deprecated
+    if (lua_isboolean(L,-1)) {
+        enable_lua = ! lua_toboolean(L,-1);
+    }
+    lua_pop(L,1);  /* pop the getglobal result */
 
-    if (lua_isboolean(L,-1) && lua_toboolean(L,-1)) {
+    lua_getglobal(L, "enable_lua"); // 3.0 and later
+    if (lua_isboolean(L,-1)) {
+        enable_lua = lua_toboolean(L,-1);
+    }
+    lua_pop(L,1);  /* pop the getglobal result */
+
+    if (!enable_lua) {
         /* disable lua */
         lua_close(L);
         L = NULL;
         first_time = FALSE;
         return;
     }
-    lua_pop(L,1);  /* pop the getglobal result */
 
     /* load global scripts */
     lua_load_global_plugins(cb, client_data, FALSE);

epan/wslua/template-init.lua

@@ -11,10 +11,10 @@
 --
 -- SPDX-License-Identifier: GPL-2.0-or-later
 
--- Set disable_lua to true to disable Lua support.
-disable_lua = false
+-- Set enable_lua to false to disable Lua support.
+enable_lua = true
 
-if disable_lua then
+if not enable_lua then
     return
 end
 

test/lua/globals_2.2.txt

@@ -720,8 +720,8 @@
     ["datafile_path"] = '<function 33>',
     ["debug"] = '<function 381>',
     ["deregister_filehandler"] = '<function 382>',
-    ["disable_lua"] = false,
     ["dofile"] = '<function 383>',
+    ["enable_lua"] = true,
     ["error"] = '<function 384>',
     ["expert"] = {
         ["group"] = {

tools/pre-commit-ignore.conf

@@ -15,6 +15,7 @@ epan/dissectors/asn1/*/*asn
 epan/nghttp2/*
 epan/wmem/wmem_strbuf.c
 epan/wmem/wmem_strutil.c
+epan/wslua/init_wslua.c
 extcap/*
 image/stock_icons/*
 mmdbresolve.c