/*      $NetBSD: tstp.c,v 1.45 2021/09/06 07:03:50 rin Exp $    */

/*
 * Copyright (c) 1981, 1993, 1994
 *      The 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. 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.
 */

#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)tstp.c      8.3 (Berkeley) 5/4/94";
#else
__RCSID("$NetBSD: tstp.c,v 1.45 2021/09/06 07:03:50 rin Exp $");
#endif
#endif                          /* not lint */

#include <sys/ioctl.h>
#include <sys/param.h>

#include <errno.h>
#include <signal.h>
#include <termios.h>
#include <unistd.h>

#include "curses.h"
#include "curses_private.h"

static int tstp_set;
static int winch_set;

static void (*otstpfn)(int) = SIG_DFL;

static struct sigaction owsa;
#ifndef TCSASOFT
#define TCSASOFT 0
#endif

/*
 * stop_signal_handler --
 *      Handle stop signals.
 */
void
__stop_signal_handler(/*ARGSUSED*/int signo)
{
        sigset_t oset, set;

        /*
         * Block window change and timer signals.  The latter is because
         * applications use timers to decide when to repaint the screen.
         */
        (void)sigemptyset(&set);
        (void)sigaddset(&set, SIGALRM);
        (void)sigaddset(&set, SIGWINCH);
        (void)sigprocmask(SIG_BLOCK, &set, &oset);

        /*
         * End the window, which also resets the terminal state to the
         * original modes.
         */
        __stopwin();

        /* Unblock SIGTSTP. */
        (void)sigemptyset(&set);
        (void)sigaddset(&set, SIGTSTP);
        (void)sigprocmask(SIG_UNBLOCK, &set, NULL);

        /* Stop ourselves. */
        (void)kill(0, SIGTSTP);

        /* Time passes ... */

        /* restart things */
        __restartwin();

        /* Reset the signals. */
        (void)sigprocmask(SIG_SETMASK, &oset, NULL);
}

/*
 * Set the TSTP handler.
 */
void
__set_stophandler(void)
{

        __CTRACE(__CTRACE_MISC, "__set_stophandler: %d\n", tstp_set);
        if (!tstp_set) {
                otstpfn = signal(SIGTSTP, __stop_signal_handler);
                tstp_set = 1;
        }
}

/*
 * Restore the TSTP handler.
 */
void
__restore_stophandler(void)
{

        __CTRACE(__CTRACE_MISC, "__restore_stophandler: %d\n", tstp_set);
        if (tstp_set) {
                (void)signal(SIGTSTP, otstpfn);
                tstp_set = 0;
        }
}

/*
 * winch_signal_handler --
 *      Handle winch signals by pushing KEY_RESIZE into the input stream.
 */
void
__winch_signal_handler(/*ARGSUSED*/int signo)
{
        struct winsize win;

        if (ioctl(fileno(_cursesi_screen->outfd), TIOCGWINSZ, &win) != -1 &&
            win.ws_row != 0 && win.ws_col != 0)
        {
                LINES = win.ws_row;
                COLS = win.ws_col;
        }
        /*
         * If there was a previous handler, call that,
         * otherwise tell getch() to send KEY_RESIZE.
         */
        if (owsa.sa_handler != SIG_DFL &&
            owsa.sa_handler != SIG_IGN &&
            owsa.sa_handler != SIG_ERR &&
            owsa.sa_handler != SIG_HOLD)
                owsa.sa_handler(signo);
        else
                _cursesi_screen->resized = 1;
}

/*
 * Set the WINCH handler.
 */
void
__set_winchhandler(void)
{

        __CTRACE(__CTRACE_MISC, "__set_winchhandler: %d\n", winch_set);
        if (!winch_set) {
                struct sigaction sa;

                sa.sa_handler = __winch_signal_handler;
                sa.sa_flags = 0;
                sigemptyset(&sa.sa_mask);
                sigaction(SIGWINCH, &sa, &owsa);
                winch_set = 1;
                __CTRACE(__CTRACE_MISC,
                    "__set_winchhandler: owsa.sa_handler=%p\n",
                    owsa.sa_handler);
        }
}

/*
 * Restore the WINCH handler.
 */
void
__restore_winchhandler(void)
{

        __CTRACE(__CTRACE_MISC, "__restore_winchhandler: %d\n", winch_set);
        if (winch_set > 0) {
                struct sigaction cwsa;

                sigaction(SIGWINCH, NULL, &cwsa);
                if (cwsa.sa_handler == owsa.sa_handler) {
                        sigaction(SIGWINCH, &owsa, NULL);
                        winch_set = 0;
                } else {
                        /*
                         * We're now using the programs WINCH handler,
                         * so don't restore the previous one.
                         */
                        winch_set = -1;
                        __CTRACE(__CTRACE_MISC, "cwsa.sa_handler = %p\n",
                            cwsa.sa_handler);
                }
        }
}

/* To allow both SIGTSTP and endwin() to come back nicely, we provide
   the following routines. */

int
__stopwin(void)
{

        __CTRACE(__CTRACE_MISC, "__stopwin\n");
        if (_cursesi_screen == NULL)
                return ERR;
        if (_cursesi_screen->endwin)
                return OK;

        /* Get the current terminal state (which the user may have changed). */
        (void)tcgetattr(fileno(_cursesi_screen->infd),
                        &_cursesi_screen->save_termios);

        __restore_stophandler();
        __restore_winchhandler();

        if (curscr != NULL) {
                __unsetattr(0);
                __mvcur((int)curscr->cury, (int)curscr->curx,
                    (int)curscr->maxy - 1, 0, 0);
        }

        if (meta_on != NULL)
                (void)tputs(meta_on, 0, __cputchar);

        if ((curscr != NULL) && (curscr->flags & __KEYPAD))
                (void)tputs(keypad_local, 0, __cputchar);
        (void)tputs(cursor_normal, 0, __cputchar);
        (void)tputs(exit_ca_mode, 0, __cputchar);
        (void)fflush(_cursesi_screen->outfd);
#ifdef BSD
        (void)setvbuf(_cursesi_screen->outfd, NULL, _IOLBF, 0);
#endif

        _cursesi_screen->endwin = 1;

        return tcsetattr(fileno(_cursesi_screen->infd), TCSASOFT | TCSADRAIN,
            &_cursesi_screen->orig_termios) ? ERR : OK;
}

void
__restartwin(void)
{
        struct winsize win;
        int nlines, ncols;

        __CTRACE(__CTRACE_MISC, "__restartwin\n");
        if (!_cursesi_screen->endwin)
                return;

        /* Reset the curses SIGTSTP and SIGWINCH signal handlers. */
        __set_stophandler();
        __set_winchhandler();

        /*
         * Check to see if the window size has changed.
         * If the application didn't update LINES and COLS,
         * set the * resized flag to tell getch() to push KEY_RESIZE.
         * Update curscr (which also updates __virtscr) and stdscr
         * to match the new size.
         */
        if (ioctl(fileno(_cursesi_screen->outfd), TIOCGWINSZ, &win) != -1 &&
            win.ws_row != 0 && win.ws_col != 0)
        {
                if (win.ws_row != LINES) {
                        LINES = win.ws_row;
                        _cursesi_screen->resized = 1;
                }
                if (win.ws_col != COLS) {
                        COLS = win.ws_col;
                        _cursesi_screen->resized = 1;
                }
        }
        /*
         * We need to make local copies of LINES and COLS, otherwise we
         * could lose if they are changed between wresize() calls.
         */
        nlines = LINES;
        ncols = COLS;
        if (curscr->maxy != nlines || curscr->maxx != ncols)
                wresize(curscr, nlines, ncols);
        if (stdscr->maxy != nlines || stdscr->maxx != ncols)
                wresize(stdscr, nlines, ncols);

        /* save the new "default" terminal state */
        (void)tcgetattr(fileno(_cursesi_screen->infd),
                        &_cursesi_screen->orig_termios);

        /* Reset the terminal state to the mode just before we stopped. */
        (void)tcsetattr(fileno(_cursesi_screen->infd), TCSASOFT | TCSADRAIN,
                        &_cursesi_screen->save_termios);

        /* Restore colours */
        __restore_colors();

        /* Reset meta */
        __restore_meta_state();

        /* Restart the screen. */
        __startwin(_cursesi_screen);

        /* Reset cursor visibility */
        __restore_cursor_vis();

        /* Repaint the screen. */
        wrefresh(curscr);
}

int
def_prog_mode(void)
{

        if (_cursesi_screen->endwin)
                return ERR;

        return tcgetattr(fileno(_cursesi_screen->infd),
                         &_cursesi_screen->save_termios) ? ERR : OK;
}

int
reset_prog_mode(void)
{

        return tcsetattr(fileno(_cursesi_screen->infd), TCSASOFT | TCSADRAIN,
                         &_cursesi_screen->save_termios) ? ERR : OK;
}

int
def_shell_mode(void)
{

        return tcgetattr(fileno(_cursesi_screen->infd),
                         &_cursesi_screen->orig_termios) ? ERR : OK;
}

int
reset_shell_mode(void)
{

        return __stopwin();
}