+int lc_initgroups(lua_State* L)
+{
+ int ret;
+ gid_t gid;
+ struct passwd *p;
+
+ if(!lua_isstring(L, 1))
+ {
+ lua_pushnil(L);
+ lua_pushstring(L, "invalid-username");
+ return 2;
+ }
+ p = getpwnam(lua_tostring(L, 1));
+ if(!p)
+ {
+ lua_pushnil(L);
+ lua_pushstring(L, "no-such-user");
+ return 2;
+ }
+ if(lua_gettop(L) < 2)
+ lua_pushnil(L);
+ switch(lua_type(L, 2))
+ {
+ case LUA_TNIL:
+ gid = p->pw_gid;
+ break;
+ case LUA_TNUMBER:
+ gid = lua_tointeger(L, 2);
+ break;
+ default:
+ lua_pushnil(L);
+ lua_pushstring(L, "invalid-gid");
+ return 2;
+ }
+ ret = initgroups(lua_tostring(L, 1), gid);
+ switch(errno)
+ {
+ case 0:
+ lua_pushboolean(L, 1);
+ lua_pushnil(L);
+ break;
+ case ENOMEM:
+ lua_pushnil(L);
+ lua_pushstring(L, "no-memory");
+ break;
+ case EPERM:
+ lua_pushnil(L);
+ lua_pushstring(L, "permission-denied");
+ break;
+ default:
+ lua_pushnil(L);
+ lua_pushstring(L, "unknown-error");
+ }
+ return 2;
+}
+
+int lc_umask(lua_State* L)
+{
+ char old_mode_string[7];
+ mode_t old_mode = umask(strtoul(luaL_checkstring(L, 1), NULL, 8));
+
+ snprintf(old_mode_string, sizeof(old_mode_string), "%03o", old_mode);
+ old_mode_string[sizeof(old_mode_string)-1] = 0;
+ lua_pushstring(L, old_mode_string);
+
+ return 1;
+}
+
+int lc_mkdir(lua_State* L)
+{
+ int ret = mkdir(luaL_checkstring(L, 1), S_IRUSR | S_IWUSR | S_IXUSR
+ | S_IRGRP | S_IWGRP | S_IXGRP
+ | S_IROTH | S_IXOTH); /* mode 775 */
+
+ lua_pushboolean(L, ret==0);
+ if(ret)
+ {
+ lua_pushstring(L, strerror(errno));
+ return 2;
+ }
+ return 1;
+}
+