usr.bin/more/signal.c

/*
 * Copyright (c) 1988 Mark Nudleman
 * Copyright (c) 1988 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static char sccsid[] = "@(#)signal.c    5.8 (Berkeley) 3/1/91";
#endif /* not lint */

/*
 * Routines dealing with signals.
 *
 * A signal usually merely causes a bit to be set in the "signals" word.
 * At some convenient time, the mainline code checks to see if any
 * signals need processing by calling psignal().
 * If we happen to be reading from a file [in iread()] at the time
 * the signal is received, we call intread to interrupt the iread.
 */

#include <less.h>
#include <signal.h>

/*
 * "sigs" contains bits indicating signals which need to be processed.
 */
int sigs;

#ifdef SIGTSTP
#define S_STOP          02
#endif
#if defined(SIGWINCH) || defined(SIGWIND)
#define S_WINCH         04
#endif

extern int sc_width, sc_height;
extern int screen_trashed;
extern int lnloop;
extern int linenums;
extern int scroll;
extern int reading;

#ifdef SIGTSTP
/*
 * "Stop" (^Z) signal handler.
 */
static void
stop()
{
        (void)signal(SIGTSTP, stop);
        sigs |= S_STOP;
        if (reading)
                intread();
}
#endif

#ifdef SIGWINCH
/*
 * "Window" change handler
 */
void
winch()
{
        (void)signal(SIGWINCH, winch);
        sigs |= S_WINCH;
        if (reading)
                intread();
}
#else
#ifdef SIGWIND
/*
 * "Window" change handler
 */
winch()
{
        (void)signal(SIGWIND, winch);
        sigs |= S_WINCH;
        if (reading)
                intread();
}
#endif
#endif

static void
purgeandquit()
{

        purge();        /* purge buffered output */
        quit();
}

/*
 * Set up the signal handlers.
 */
init_signals(on)
        int on;
{
        if (on)
        {
                /*
                 * Set signal handlers.
                 */
                (void)signal(SIGINT, purgeandquit);
#ifdef SIGTSTP
                (void)signal(SIGTSTP, stop);
#endif
#ifdef SIGWINCH
                (void)signal(SIGWINCH, winch);
#else
#ifdef SIGWIND
                (void)signal(SIGWIND, winch);
#endif
#endif
        } else
        {
                /*
                 * Restore signals to defaults.
                 */
                (void)signal(SIGINT, SIG_DFL);
#ifdef SIGTSTP
                (void)signal(SIGTSTP, SIG_DFL);
#endif
#ifdef SIGWINCH
                (void)signal(SIGWINCH, SIG_IGN);
#endif
#ifdef SIGWIND
                (void)signal(SIGWIND, SIG_IGN);
#endif
        }
}

/*
 * Process any signals we have received.
 * A received signal cause a bit to be set in "sigs".
 */
psignals()
{
        register int tsignals;

        if ((tsignals = sigs) == 0)
                return;
        sigs = 0;

#ifdef S_WINCH
        if (tsignals & S_WINCH)
        {
                int old_width, old_height;
                /*
                 * Re-execute get_term() to read the new window size.
                 */
                old_width = sc_width;
                old_height = sc_height;
                get_term();
                if (sc_width != old_width || sc_height != old_height)
                {
                        scroll = (sc_height + 1) / 2;
                        screen_trashed = 1;
                }
        }
#endif
#ifdef SIGTSTP
        if (tsignals & S_STOP)
        {
                /*
                 * Clean up the terminal.
                 */
#ifdef SIGTTOU
                (void)signal(SIGTTOU, SIG_IGN);
#endif
                lower_left();
                clear_eol();
                deinit();
                (void)flush();
                raw_mode(0);
#ifdef SIGTTOU
                (void)signal(SIGTTOU, SIG_DFL);
#endif
                (void)signal(SIGTSTP, SIG_DFL);
                (void)kill(getpid(), SIGTSTP);
                /*
                 * ... Bye bye. ...
                 * Hopefully we'll be back later and resume here...
                 * Reset the terminal and arrange to repaint the
                 * screen when we get back to the main command loop.
                 */
                (void)signal(SIGTSTP, stop);
                raw_mode(1);
                init();
                screen_trashed = 1;
        }
#endif
}