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tstp.c revision 1.5 
      1 /*
      2  * Copyright (c) 1981, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #ifndef lint
     35 static char sccsid[] = "@(#)tstp.c	8.2 (Berkeley) 11/2/93";
     36 #endif /* not lint */
     37 
     38 #include <curses.h>
     39 #include <errno.h>
     40 #include <signal.h>
     41 #include <termios.h>
     42 #include <unistd.h>
     43 
     44 
     45 /*
     46  * stop_signal_handler --
     47  *	Handle stop signals.
     48  */
     49 void
     50 __stop_signal_handler(signo)
     51 	int signo;
     52 {
     53 	struct termios save;
     54 	sigset_t oset, set;
     55 
     56 	/* Get the current terminal state (which the user may have changed). */
     57 	if (tcgetattr(STDIN_FILENO, &save))
     58 		return;
     59 
     60 	/*
     61 	 * Block window change and timer signals.  The latter is because
     62 	 * applications use timers to decide when to repaint the screen.
     63 	 */
     64 	(void)sigemptyset(&set);
     65 	(void)sigaddset(&set, SIGALRM);
     66 	(void)sigaddset(&set, SIGWINCH);
     67 	(void)sigprocmask(SIG_BLOCK, &set, &oset);
     68 
     69 	/*
     70 	 * End the window, which also resets the terminal state to the
     71 	 * original modes.
     72 	 */
     73 	endwin();
     74 
     75 	/* Unblock SIGTSTP. */
     76 	(void)sigemptyset(&set);
     77 	(void)sigaddset(&set, SIGTSTP);
     78 	(void)sigprocmask(SIG_UNBLOCK, &set, NULL);
     79 
     80 	/* Stop ourselves. */
     81 	__restore_stophandler();
     82 	(void)kill(0, SIGTSTP);
     83 
     84 	/* Time passes ... */
     85 
     86 	/* Reset the curses SIGTSTP signal handler. */
     87 	__set_stophandler();
     88 
     89 	/* save the new "default" terminal state */
     90 	(void)tcgetattr(STDIN_FILENO, &__orig_termios);
     91 
     92 	/* Reset the terminal state to the mode just before we stopped. */
     93 	(void)tcsetattr(STDIN_FILENO, __tcaction ?
     94 	    TCSASOFT | TCSADRAIN : TCSADRAIN, &save);
     95 
     96 	/* Restart the screen. */
     97 	__startwin();
     98 
     99 	/* Repaint the screen. */
    100 	wrefresh(curscr);
    101 
    102 	/* Reset the signals. */
    103 	(void)sigprocmask(SIG_SETMASK, &oset, NULL);
    104 }
    105 
    106 static void (*otstpfn)() = SIG_DFL;
    107 
    108 /*
    109  * Set the TSTP handler.
    110  */
    111 void
    112 __set_stophandler()
    113 {
    114 	otstpfn = signal(SIGTSTP, __stop_signal_handler);
    115 }
    116 
    117 /*
    118  * Restore the TSTP handler.
    119  */
    120 void
    121 __restore_stophandler()
    122 {
    123 	(void)signal(SIGTSTP, otstpfn);
    124 }
    125