#include <u.h>#include <libc.h>#include <auth.h> voidmain(int argc, char *argv[]){	char cmd[256];	int fd; 	argv0 = argv[0];	if (rfork(RFENVG|RFNAMEG) < 0)		sysfatal("can't make new pgrp"); 	fd = open("#c/user", OWRITE);	if (fd < 0)		sysfatal("can't open #c/user");	if (write(fd, "none", strlen("none")) < 0)		sysfatal("can't become none");	close(fd); 	if (newns("none", nil) < 0)		sysfatal("can't build namespace"); 	if (argc > 1) {		strecpy(cmd, cmd+sizeof cmd, argv[1]);		exec(cmd, &argv[1]);		if (strncmp(cmd, "/", 1) != 0		&& strncmp(cmd, "./", 2) != 0		&& strncmp(cmd, "../", 3) != 0) {			snprint(cmd, sizeof cmd, "/bin/%s", argv[1]);			exec(cmd, &argv[1]);		}	} else {		strcpy(cmd, "/bin/rc");		execl(cmd, cmd, nil);	}	sysfatal(cmd);}