+static int nixio_getpid(lua_State *L) {
+ lua_pushinteger(L, getpid());
+ return 1;
+}
+
+static int nixio_getppid(lua_State *L) {
+ lua_pushinteger(L, getppid());
+ return 1;
+}
+
+static int nixio_getuid(lua_State *L) {
+ lua_pushinteger(L, getuid());
+ return 1;
+}
+
+static int nixio_getgid(lua_State *L) {
+ lua_pushinteger(L, getgid());
+ return 1;
+}
+
+static int nixio_setgid(lua_State *L) {
+ gid_t gid;
+ if (lua_isstring(L, 1)) {
+ struct group *g = getgrnam(lua_tostring(L, 1));
+ gid = (!g) ? -1 : g->gr_gid;
+ } else if (lua_isnumber(L, 1)) {
+ gid = lua_tointeger(L, 1);
+ } else {
+ return luaL_argerror(L, 1, "supported values: <groupname>, <gid>");
+ }
+
+ return nixio__pstatus(L, !setgid(gid));
+}
+
+static int nixio_setuid(lua_State *L) {
+ uid_t uid;
+ if (lua_isstring(L, 1)) {
+ struct passwd *p = getpwnam(lua_tostring(L, 1));
+ uid = (!p) ? -1 : p->pw_uid;
+ } else if (lua_isnumber(L, 1)) {
+ uid = lua_tointeger(L, 1);
+ } else {
+ return luaL_argerror(L, 1, "supported values: <username>, <uid>");
+ }
+
+ return nixio__pstatus(L, !setuid(uid));
+}
+