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/* signals.c -- signal handline routine for vlock
*
* This program is copyright (C) 1994 Michael K. Johnson, and is free
* software which is freely distributable under the terms of the
* GNU public license, included as the file COPYING in this
* distribution. It is NOT public domain software, and any
* redistribution not permitted by the GNU Public License is
* expressly forbidden without prior written permission from
* the author.
*
*/
/* RCS log:
* $Log: signals.c,v $
* Revision 1.9 1996/05/17 02:50:28 johnsonm
* include path changes
*
* Revision 1.8 1994/07/03 13:09:18 johnsonm
* Added support for setting the signal mask with or without saving the
* old mask.
* Added handling SIGTSTP back in; apparantly it is important in some cases.
*
* Revision 1.7 1994/07/03 12:01:53 johnsonm
* Added SIGINT handling so ctrl-break won't kill it.
*
* Revision 1.6 1994/03/23 17:01:25 johnsonm
* Fixed SIGQUIT bug.
* Added support for non-vt ttys.
*
* Revision 1.5 1994/03/19 14:28:18 johnsonm
* Removed support for silly two-process idea. signal mask no longer
* inverse of what I want. (I may have fixed this in an earlier
* version, and forgotten to log it.)
*
* Revision 1.4 1994/03/16 20:11:04 johnsonm
* It mostly works -- child can still be killed by sigchld, which
* propogates to parent, which kills lock program. However, locking
* all VC's does work if there is no other way to log on...
*
* Revision 1.3 1994/03/15 18:27:33 johnsonm
* Added a few more signals, in preparation for two-process model.
*
* Revision 1.2 1994/03/13 17:27:44 johnsonm
* Now using SIGUSR{1,2} correctly with release_vt() and acquire_vt() to
* keep from switching VC's.
*
* Revision 1.1 1994/03/13 16:28:16 johnsonm
* Initial revision
*
*/
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <sys/vt.h>
#include "vlock.h"
static char rcsid[] = "$Id: signals.c,v 1.9 1996/05/17 02:50:28 johnsonm Exp johnsonm $";
/* In release_vt() and acquire_vt(), anything which is done in
* release_vt() must be undone in acquire_vt(). Right now, that's
* not much...
*/
/* This is called by a signal whenever a user tries to change the VC
with a ALT-Fn key */
void release_vt(int signo) {
if (!o_lock_all)
ioctl(vfd, VT_RELDISP, 1); /* kernel is allowed to switch */
else
ioctl(vfd, VT_RELDISP, 0); /* kernel is not allowed to switch */
}
/* This is called whenever a user switches to that VC */
void acquire_vt(int signo) {
/* This call is not currently required under Linux, but it won't hurt,
either... */
ioctl(vfd, VT_RELDISP, VT_ACKACQ);
}
void signal_ignorer(int signo) {
return;
}
static sigset_t osig; /* for both mask_signals() and restore_signals() */
void set_signal_mask(int save) {
static sigset_t sig;
static struct sigaction sa;
/* We don't want to get any signals we don't have to, but there are */
/* several we must get. I don't know whether to take the current */
/* signal mask and change it or to do a sigfillset and go from there. */
/* The code should handle either, I think. */
sigprocmask(SIG_SETMASK, NULL, &sig);
sigdelset(&sig, SIGUSR1);
sigdelset(&sig, SIGUSR2);
sigaddset(&sig, SIGTSTP);
sigaddset(&sig, SIGTTIN);
sigaddset(&sig, SIGTTOU);
sigaddset(&sig, SIGHUP);
sigaddset(&sig, SIGCHLD);
sigaddset(&sig, SIGQUIT);
sigaddset(&sig, SIGINT);
if (save)
sigprocmask(SIG_SETMASK, &sig, &osig);
else
sigprocmask(SIG_SETMASK, &sig, NULL);
/* we set SIGUSR{1,2} to point to *_vt() above */
sigemptyset(&(sa.sa_mask));
sa.sa_flags = SA_RESTART;
sa.sa_handler = release_vt;
sigaction(SIGUSR1, &sa, NULL);
sa.sa_handler = acquire_vt;
sigaction(SIGUSR2, &sa, NULL);
/* Need to handle some signals so that we don't get killed by them */
sa.sa_handler = signal_ignorer;
sigaction(SIGHUP, &sa, NULL);
sigaction(SIGQUIT, &sa, NULL);
sigaction(SIGINT, &sa, NULL);
sigaction(SIGTSTP, &sa, NULL);
}
void mask_signals(void) {
set_signal_mask(1); /* set the signal masks and handlers and save */
}
void restore_signals(void) {
/* This probably isn't useful, but I'm including it anyway... */
/* It might become useful later, specifically if someone wants
to include this code within another program. */
sigprocmask(SIG_SETMASK, &osig, NULL);
}
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