+int lc_setgid(lua_State* L)
+{
+ int gid = -1;
+ if(lua_gettop(L) < 1)
+ return 0;
+ if(!lua_isnumber(L, 1) && lua_tostring(L, 1))
+ {
+ /* Passed GID is actually a string, so look up the GID */
+ struct group *g;
+ g = getgrnam(lua_tostring(L, 1));
+ if(!g)
+ {
+ lua_pushboolean(L, 0);
+ lua_pushstring(L, "no-such-group");
+ return 2;
+ }
+ gid = g->gr_gid;
+ }
+ else
+ {
+ gid = lua_tonumber(L, 1);
+ }
+
+ if(gid>-1)
+ {
+ /* Ok, attempt setgid */
+ errno = 0;
+ if(setgid(gid))
+ {
+ /* Fail */
+ lua_pushboolean(L, 0);
+ switch(errno)
+ {
+ case EINVAL:
+ lua_pushstring(L, "invalid-gid");
+ break;
+ case EPERM:
+ lua_pushstring(L, "permission-denied");
+ break;
+ default:
+ lua_pushstring(L, "unknown-error");
+ }
+ return 2;
+ }
+ else
+ {
+ /* Success! */
+ lua_pushboolean(L, 1);
+ return 1;
+ }
+ }
+
+ /* Seems we couldn't find a valid GID to switch to */
+ lua_pushboolean(L, 0);
+ lua_pushstring(L, "invalid-gid");
+ return 2;
+}
+