Mercurial > hg > toybox
diff toys/oneit.c @ 34:c1f4f9101af7
Add oneit.
author | Rob Landley <rob@landley.net> |
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date | Sat, 25 Nov 2006 13:48:02 -0500 |
parents | |
children | 1e8f4b05cb65 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/toys/oneit.c Sat Nov 25 13:48:02 2006 -0500 @@ -0,0 +1,45 @@ +/* oneit.c, tiny one-process init replacement. + * + * Copyright 2005 by Rob Landley <rob@landley.net>. + */ + +#include "toys.h" +#include <sys/reboot.h> + +// 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. + +int 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); + open("/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); +}