Mega Top 1/os2_top1.zip/os2_top1/APPS/UTILS/H-O/LESS177/SIGNAL.C

C/C++ Source or Header | 1993-01-05 | 5KB | 258 lines

/*
 * 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.
 */
public int sigs;

#if OS2
public int os2sigs;
#endif

#define    S_INTERRUPT    01
#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 swindow;
extern int screen_trashed;
extern int lnloop;
extern int linenums;
extern int scroll;
extern int reading;

/*
 * Interrupt signal handler.
 */
    /* ARGSUSED*/
    static HANDLER
u_interrupt(type)
    int type;
{
#if OS2
        signal(type, SIG_ACK);
#endif
    SIGNAL(SIGINT, u_interrupt);
    sigs |= S_INTERRUPT;
    if (reading)
        intread();
}

    public void
fake_interrupt()
{
    sigs |= S_INTERRUPT;
}

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

#ifdef SIGWINCH
/*
 * "Window" change handler
 */
    /* ARGSUSED*/
    public HANDLER
winch(type)
    int type;
{
    SIGNAL(SIGWINCH, winch);
    sigs |= S_WINCH;
    if (reading)
        intread();
}
#else
#ifdef SIGWIND
/*
 * "Window" change handler
 */
    /* ARGSUSED*/
    public HANDLER
winch(type)
    int type;
{
    SIGNAL(SIGWIND, winch);
    sigs |= S_WINCH;
    if (reading)
        intread();
}
#endif
#endif

/*
 * Set up the signal handlers.
 */
    public void
init_signals(on)
    int on;
{
    if (on)
    {
        /*
         * Set signal handlers.
         */
        (void) SIGNAL(SIGINT, u_interrupt);
#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".
 */
    public void
psignals()
{
    register int tsignals;
#if OS2
    if (os2sigs != 0)
    {
            int old_width, old_height;
        os2sigs=0;

            /*
         * Re-execute get_term() to read the new window size.
         */
        old_width = sc_width;
        old_height = sc_height;
        swindow = -1;
        get_term();
        if (sc_width != old_width || sc_height != old_height)
        {
                scroll = (sc_height + 1) / 2;
            screen_trashed = 1;
            sigs=1;   /* sound the bell */
            return;
        }
    }
#endif

    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;
        swindow = -1;
        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
        SIGNAL(SIGTTOU, SIG_IGN);
#endif
        lower_left();
        clear_eol();
        deinit();
        flush();
        raw_mode(0);
#ifdef SIGTTOU
        SIGNAL(SIGTTOU, SIG_DFL);
#endif
        SIGNAL(SIGTSTP, SIG_DFL);
        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.
         */
        SIGNAL(SIGTSTP, stop);
        raw_mode(1);
        init();
        screen_trashed = 1;
    }
#endif
    if (tsignals & S_INTERRUPT)
    {
        bell();
        /*
         * {{ You may wish to replace the bell() with
         *    error("Interrupt", NULL_PARG); }}
         */

        /*
         * If we were interrupted while in the "calculating
         * line numbers" loop, turn off line numbers.
         */
        if (lnloop)
        {
            lnloop = 0;
            if (linenums == 2)
                screen_trashed = 1;
            linenums = 0;
            error("Line numbers turned off", NULL_PARG);
        }

    }
}