lua: reimplement mp.subprocess_detached() by invoking the "run" command

The "run" command is old. I'm not sure why the separate Lua
implementation was added. But maybe it as because the "run" command used
to be limited to a small number of arguments. This limit has been
removed a while ago. In any case, the old implementation is not needed
anymore.

DOCS/man/lua.rst

@@ -682,6 +682,9 @@ strictly part of the guaranteed API.
 
     The function returns ``nil``.
 
+    This is a legacy wrapper around calling the ``run`` command with
+    ``mp.commandv`` and other functions.
+
 ``utils.getpid()``
     Returns the process ID of the running mpv process. This can be used to identify
     the calling mpv when launching (detached) subprocesses.

player/lua.c

@@ -1187,35 +1187,6 @@ static int script_join_path(lua_State *L)
     return 1;
 }
 
-static int script_subprocess_detached(lua_State *L)
-{
-    struct script_ctx *ctx = get_ctx(L);
-    luaL_checktype(L, 1, LUA_TTABLE);
-    void *tmp = mp_lua_PITA(L);
-
-    lua_getfield(L, 1, "args"); // args
-    int num_args = mp_lua_len(L, -1);
-    char *args[256];
-    if (num_args > MP_ARRAY_SIZE(args) - 1) // last needs to be NULL
-        luaL_error(L, "too many arguments");
-    if (num_args < 1)
-        luaL_error(L, "program name missing");
-    for (int n = 0; n < num_args; n++) {
-        lua_pushinteger(L, n + 1); // args n
-        lua_gettable(L, -2); // args arg
-        args[n] = talloc_strdup(tmp, lua_tostring(L, -1));
-        if (!args[n])
-            luaL_error(L, "program arguments must be strings");
-        lua_pop(L, 1); // args
-    }
-    args[num_args] = NULL;
-    lua_pop(L, 1); // -
-
-    mp_subprocess_detached(ctx->log, args);
-    lua_pushnil(L);
-    return 1;
-}
-
 static int script_getpid(lua_State *L)
 {
     lua_pushnumber(L, mp_getpid());
@@ -1309,7 +1280,6 @@ static const struct fn_entry utils_fns[] = {
     FN_ENTRY(file_info),
     FN_ENTRY(split_path),
     FN_ENTRY(join_path),
-    FN_ENTRY(subprocess_detached),
     FN_ENTRY(getpid),
     FN_ENTRY(parse_json),
     FN_ENTRY(format_json),

player/lua/defaults.lua

@@ -640,4 +640,8 @@ function mp_utils.subprocess(t)
     return res
 end
 
+function mp_utils.subprocess_detached(t)
+    mp.commandv("run", unpack(t.args))
+end
+
 return {}