/*
 * init.c version 20130705
 * Daniel Cegielka
 * Public domain.
 */

#include <fcntl.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/reboot.h>
#include <linux/kd.h>

static void
sigchild(int sig)
{
	while(waitpid(-1, NULL, WNOHANG) > 0);
}

static void
openconsole(void)
{
	int fd;

	if((fd = open("/dev/console", O_RDWR|O_NOCTTY)) >= 0){
		dup2(fd, 0);
		dup2(fd, 1);
		dup2(fd, 2);
		if(fd > 2)
			close(fd);
	}
}

int
main(int argc, char **argv)
{
	int i, fd, l;
	struct sigaction sa;
	pid_t t;

	if(getpid() != 1)
		return 1;
	for(i = 0, l = 0; i < argc; i++)
		l = strlen(argv[i]) + 1;
	if(l > 1){
		memset(argv[0], 0, l);
		strncpy(argv[0], "init", l - 1);
	}
	for(i = 1; i < NSIG; i++)
		if(i != SIGCHLD)
			(void)signal(i, SIG_IGN);
	reboot(RB_DISABLE_CAD);
	if((fd = open("/dev/console", O_RDWR|O_NOCTTY)) >= 0){
		ioctl(fd, KDSIGACCEPT, SIGWINCH);
		close(fd);
	} else
		ioctl(0, KDSIGACCEPT, SIGWINCH);
	for(i = 0; i < 3; i++){
		close(i);
		open("/dev/null", O_RDWR, 0);
	}
	if(!fork()){
		setsid();
		openconsole();
		tcsetpgrp(0, getpgrp());
		execl("/bin/sh", "sh", "/etc/rc", NULL);
		while(waitpid(t, NULL, 0) != t);
	}
	sigemptyset(&sa.sa_mask);
	sa.sa_sigaction = 0;
	sa.sa_flags = SA_RESTART|SA_NOCLDSTOP;
	sa.sa_handler = sigchild;
	sigaction(SIGCHLD, &sa, 0);
	for(;;)
		pause();
}