/* vi: set sw=4 ts=4: * * oneit.c, tiny one-process init replacement. * * Copyright 2005, 2007 by Rob Landley <rob@landley.net>. * * Not in SUSv3. USE_ONEIT(NEWTOY(oneit, "+<1c:p", TOYFLAG_SBIN)) config ONEIT bool "oneit" default y help usage: oneit [-p] [-c /dev/tty0] command [...] A simple init program that runs a single supplied command line with a controlling tty (so CTRL-C can kill it). -p Power off instead of rebooting when command exits. -c Which console device to use. The oneit command runs the supplied command line as a child process (because PID 1 has signals blocked), attached to /dev/tty0, in its own session. Then oneit reaps zombies until the child exits, at which point it reboots (or with -p, powers off) the system. */ #include "toys.h" #include <sys/reboot.h> DEFINE_GLOBALS( char *console; ) #define TT this.oneit // The minimum amount of work necessary to get ctrl-c and such to work is: // // - Fork a child (PID 1 is special: can't exit, has various signals blocked). // - Do a setsid() (so we have our own session). // - In the child, attach stdio to /dev/tty0 (/dev/console is special) // - 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(). I could stick a kill -1 in there. void oneit_main(void) { int i; pid_t pid; // Create a new child process. pid = vfork(); if (pid) { // pid 1 just reaps zombies until it gets its child, then halts the system. while (pid!=wait(&i)); sync(); reboot(toys.optflags ? RB_POWER_OFF : RB_AUTOBOOT); } // Redirect stdio to /dev/tty0, with new session ID, so ctrl-c works. setsid(); for (i=0; i<3; i++) { close(i); xopen(TT.console ? TT.console : "/dev/tty0",O_RDWR); } // Can't xexec() here, because we vforked so we don't want to error_exit(). toy_exec(toys.optargs); execvp(*toys.optargs, toys.optargs); _exit(127); }