/* oneit.c, tiny one-process init replacement.
 *
 * Copyright 2005 by Rob Landley.  Released under gpl v2.
 */
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/reboot.h>

// World's most brain-dead init program.  Does the minimum amount of work
// necessary to get ctrl-c and such to work.
//
// Fork a child (PID 1 is special: it can't exit and has various signals
// blocked).  In the child, attach stdio to /dev/tty0 (so we have a controlling
// tty, plus do a setsid()), then exec the rest of the command line.
//
// PID 1 then reaps zombies until the child process it spawned exits, at which
// point it calls sync() and reboot().

int main(int argc, char *argv[])
{
  int a;
  pid_t pid;
  
  // pid 1 just reaps zombies until it gets its child, then halts the system.
  pid=fork();
  if(pid) {
    while(pid!=wait());
    sync();
    reboot(LINUX_REBOOT_CMD_HALT);
  }
    
  // Redirect stdio to /dev/tty0, with new session ID, so ctrl-c works.
  setsid();
  for(a=0;a<3;a++) {
    close(a);
    open("/dev/tty0",O_RDWR);
  }
  
  execvp(argv[1],argv+1);
}