wslua: expose some libwiretap APIs in Lua.

Provide Lua version of wtap_file_type_subtype_string(),
wtap_file_type_subtype_short_string(), and
wtap_short_string_to_file_type_subtype().

This will be backported to the 3.2 and 3.4 branches, to allow scripts
not run on the bleeding-edge version to use them.

docbook/CMakeLists.txt

@@ -323,6 +323,7 @@ set(WSLUA_MODULES
 	${CMAKE_SOURCE_DIR}/epan/wslua/wslua_frame_info.c
 	${CMAKE_SOURCE_DIR}/epan/wslua/wslua_capture_info.c
 	${CMAKE_SOURCE_DIR}/epan/wslua/wslua_dir.c
+	${CMAKE_SOURCE_DIR}/epan/wslua/wslua_wtap.c
 	${CMAKE_SOURCE_DIR}/epan/wslua/wslua_util.c
 	${CMAKE_SOURCE_DIR}/epan/wslua/wslua_struct.c
 )

docbook/wsluarm.adoc

@@ -243,6 +243,7 @@ include::{build_dir}/wsluarm_src/wslua_tree.adoc[]
 include::{build_dir}/wsluarm_src/wslua_tvb.adoc[]
 include::{build_dir}/wsluarm_src/wslua_file.adoc[]
 include::{build_dir}/wsluarm_src/wslua_dir.adoc[]
+include::{build_dir}/wsluarm_src/wslua_wtap.adoc[]
 include::{build_dir}/wsluarm_src/wslua_util.adoc[]
 include::{build_dir}/wsluarm_src/wslua_int64.adoc[]
 include::{build_dir}/wsluarm_src/wslua_struct.adoc[]

epan/wslua/CMakeLists.txt

@@ -43,6 +43,7 @@ set(WSLUA_MODULES
 	${CMAKE_CURRENT_SOURCE_DIR}/wslua_tree.c
 	${CMAKE_CURRENT_SOURCE_DIR}/wslua_tvb.c
 	${CMAKE_CURRENT_SOURCE_DIR}/wslua_util.c
+	${CMAKE_CURRENT_SOURCE_DIR}/wslua_wtap.c
 )
 
 set(WSLUA_FILES

epan/wslua/wslua_wtap.c

@@ -0,0 +1,85 @@
+/*
+ * wslua_wtap.c
+ *
+ * Wireshark's interface to the Lua Programming Language
+ * for various libwiretap utility functions.
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "config.h"
+
+/* WSLUA_MODULE Wtap Wtap Functions For Handling Capture File Types */
+
+#include <limits.h>
+
+#include "wslua.h"
+#include <wiretap/wtap.h>
+
+WSLUA_FUNCTION wslua_wtap_file_type_subtype_description(lua_State* LS) {
+    /*
+    Get a string describing a capture file type, given a filetype
+    value for that file type.
+
+    @since 3.2.12, 3.4.4
+    */
+#define WSLUA_ARG_file_type_subtype_description_FILETYPE 1 /* The type for which the description is to be fetched - a number entry from the `wtap_filetypes` table in `init.lua`. */
+    lua_Number filetype = luaL_checknumber(LS,WSLUA_ARG_file_type_subtype_description_FILETYPE);
+    /* wtap_file_type_subtype_string()'s name isn't really descriptive. */
+    if (filetype > INT_MAX) {
+        /* Too big. */
+        lua_pushnil(LS);
+    } else {
+        const gchar* str = wtap_file_type_subtype_string((int)filetype);
+        if (str == NULL)
+            lua_pushnil(LS);
+        else
+            lua_pushstring(LS,str);
+    }
+    WSLUA_RETURN(1); /* The description of the file type with that filetype value, or nul if there is no such file type. */
+}
+
+WSLUA_FUNCTION wslua_wtap_file_type_subtype_name(lua_State* LS) {
+    /*
+    Get a string giving the name for a capture file type, given a filetype
+    value for that file type.
+
+    @since 3.2.12, 3.4.4
+    */
+#define WSLUA_ARG_file_type_subtype_name_FILETYPE 1 /* The type for which the name is to be fetched - a number entry from the `wtap_filetypes` table in `init.lua`. */
+    lua_Number filetype = luaL_checknumber(LS,WSLUA_ARG_file_type_subtype_name_FILETYPE);
+    /* wtap_file_type_subtype_string()'s name isn't really descriptive. */
+    if (filetype > INT_MAX) {
+        /* Too big. */
+        lua_pushnil(LS);
+    } else {
+        const gchar* str = wtap_file_type_subtype_short_string((int)filetype);
+        if (str == NULL)
+            lua_pushnil(LS);
+        else
+           lua_pushstring(LS,str);
+    }
+    WSLUA_RETURN(1); /* The name of the file type with that filetype value, or nul if there is no such file type. */
+}
+
+WSLUA_FUNCTION wslua_wtap_name_to_file_type_subtype(lua_State* LS) {
+    /*
+    Get a filetype value for a file type, given the name for that
+    file type.
+
+    @since 3.2.12, 3.4.4
+    */
+#define WSLUA_ARG_name_to_file_type_subtype_NAME 1 /* A timestamp value to convert. */
+    const char* name = luaL_checkstring(LS,WSLUA_ARG_name_to_file_type_subtype_NAME);
+    /* wtap_short_string_to_file_type_subtype()'s name isn't really descriptive. */
+    lua_Number filetype = wtap_short_string_to_file_type_subtype(name);
+    if (filetype == -1)
+        lua_pushnil(LS);
+    else
+        lua_pushnumber(LS,filetype);
+    WSLUA_RETURN(1); /* The filetype value for the file type with that name, or nil if there is no such file type. */
+}