Add "MINETEST_MOD_PATH" environment variable (#11515)

This adds an environment variable MINETEST_MOD_PATH.
When it exists, Minetest will look there for mods in addition to ~/.minetest/mods/.

Author: emixa-d

builtin/mainmenu/pkgmgr.lua

@@ -682,11 +682,9 @@ function pkgmgr.preparemodlist(data)
 	local game_mods = {}
 
 	--read global mods
-	local modpath = core.get_modpath()
-
-	if modpath ~= nil and
-		modpath ~= "" then
-		get_mods(modpath,global_mods)
+	local modpaths = core.get_modpaths()
+	for _, modpath in ipairs(modpaths) do
+		get_mods(modpath, global_mods)
 	end
 
 	for i=1,#global_mods,1 do

doc/menu_lua_api.txt

@@ -219,7 +219,13 @@ Package - content which is downloadable from the content db, may or may not be i
     * returns path to global user data,
       the directory that contains user-provided mods, worlds, games, and texture packs.
 * core.get_modpath() (possible in async calls)
-    * returns path to global modpath
+    * returns path to global modpath, where mods can be installed
+* core.get_modpaths() (possible in async calls)
+    * returns list of paths to global modpaths, where mods have been installed
+
+      The difference with "core.get_modpath" is that no mods should be installed in these
+      directories by Minetest -- they might be read-only.
+
 * core.get_clientmodpath() (possible in async calls)
     * returns path to global client-side modpath
 * core.get_gamepath() (possible in async calls)

doc/minetest.6

@@ -119,6 +119,9 @@ Display an interactive terminal over ncurses during execution.
 .TP
 .B MINETEST_SUBGAME_PATH
 Colon delimited list of directories to search for games.
+.TP
+.B MINETEST_MOD_PATH
+Colon delimited list of directories to search for mods.
 
 .SH BUGS
 Please report all bugs at https://github.com/minetest/minetest/issues.

src/content/subgames.cpp

@@ -113,6 +113,10 @@ SubgameSpec findSubgame(const std::string &id)
 	if (user != share || user_game)
 		mods_paths.insert(user + DIR_DELIM + "mods");
 
+	for (const std::string &mod_path : getEnvModPaths()) {
+		mods_paths.insert(mod_path);
+	}
+
 	// Get meta
 	std::string conf_path = game_path + DIR_DELIM + "game.conf";
 	Settings conf;
@@ -384,3 +388,13 @@ void loadGameConfAndInitWorld(const std::string &path, const std::string &name,
 	if (new_game_settings)
 		delete game_settings;
 }
+
+std::vector<std::string> getEnvModPaths()
+{
+	const char *c_mod_path = getenv("MINETEST_MOD_PATH");
+	std::vector<std::string> paths;
+	Strfnd search_paths(c_mod_path ? c_mod_path : "");
+	while (!search_paths.at_end())
+		paths.push_back(search_paths.next(PATH_DELIM));
+	return paths;
+}

src/content/subgames.h

@@ -58,6 +58,8 @@ SubgameSpec findWorldSubgame(const std::string &world_path);
 
 std::set<std::string> getAvailableGameIds();
 std::vector<SubgameSpec> getAvailableGames();
+// Get the list of paths to mods in the environment variable $MINETEST_MOD_PATH
+std::vector<std::string> getEnvModPaths();
 
 bool getWorldExists(const std::string &world_path);
 //! Try to get the displayed name of a world

src/script/lua_api/l_mainmenu.cpp

@@ -502,6 +502,21 @@ int ModApiMainMenu::l_get_modpath(lua_State *L)
 	return 1;
 }
 
+/******************************************************************************/
+int ModApiMainMenu::l_get_modpaths(lua_State *L)
+{
+	int index = 1;
+	lua_newtable(L);
+	ModApiMainMenu::l_get_modpath(L);
+	lua_rawseti(L, -2, index);
+	for (const std::string &component : getEnvModPaths()) {
+		index++;
+		lua_pushstring(L, component.c_str());
+		lua_rawseti(L, -2, index);
+	}
+	return 1;
+}
+
 /******************************************************************************/
 int ModApiMainMenu::l_get_clientmodpath(lua_State *L)
 {
@@ -856,6 +871,7 @@ void ModApiMainMenu::Initialize(lua_State *L, int top)
 	API_FCT(get_mapgen_names);
 	API_FCT(get_user_path);
 	API_FCT(get_modpath);
+	API_FCT(get_modpaths);
 	API_FCT(get_clientmodpath);
 	API_FCT(get_gamepath);
 	API_FCT(get_texturepath);
@@ -889,6 +905,7 @@ void ModApiMainMenu::InitializeAsync(lua_State *L, int top)
 	API_FCT(get_mapgen_names);
 	API_FCT(get_user_path);
 	API_FCT(get_modpath);
+	API_FCT(get_modpaths);
 	API_FCT(get_clientmodpath);
 	API_FCT(get_gamepath);
 	API_FCT(get_texturepath);

src/script/lua_api/l_mainmenu.h

@@ -112,6 +112,8 @@ class ModApiMainMenu: public ModApiBase
 
 	static int l_get_modpath(lua_State *L);
 
+	static int l_get_modpaths(lua_State *L);
+
 	static int l_get_clientmodpath(lua_State *L);
 
 	static int l_get_gamepath(lua_State *L);

src/unittest/CMakeLists.txt

@@ -44,6 +44,7 @@ set (UNITTEST_CLIENT_SRCS
 
 set (TEST_WORLDDIR ${CMAKE_CURRENT_SOURCE_DIR}/test_world)
 set (TEST_SUBGAME_PATH ${CMAKE_CURRENT_SOURCE_DIR}/../../games/devtest)
+set (TEST_MOD_PATH ${CMAKE_CURRENT_SOURCE_DIR}/test_mod)
 
 configure_file(
 	"${CMAKE_CURRENT_SOURCE_DIR}/test_config.h.in"

src/unittest/test_config.h.in

@@ -4,3 +4,4 @@
 
 #define TEST_WORLDDIR "@TEST_WORLDDIR@"
 #define TEST_SUBGAME_PATH "@TEST_SUBGAME_PATH@"
+#define TEST_MOD_PATH "@TEST_MOD_PATH@"

src/unittest/test_mod/test_mod/init.lua

@@ -0,0 +1 @@
+-- deliberately empty