distrib/utils/more/signal.c

   1 /*      $NetBSD: signal.c,v 1.5 2003/10/13 14:34:25 agc Exp $   */
   2
   3 /*
   4  * Copyright (c) 1988 Mark Nudelman
   5  * Copyright (c) 1988, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #include <sys/cdefs.h>
  34 #ifndef lint
  35 #if 0
  36 static char sccsid[] = "@(#)signal.c    8.1 (Berkeley) 6/6/93";
  37 #else
  38 __RCSID("$NetBSD: signal.c,v 1.5 2003/10/13 14:34:25 agc Exp $");
  39 #endif
  40 #endif /* not lint */
  41
  42 /*
  43  * Routines dealing with signals.
  44  *
  45  * A signal usually merely causes a bit to be set in the "signals" word.
  46  * At some convenient time, the mainline code checks to see if any
  47  * signals need processing by calling psignal().
  48  * If we happen to be reading from a file [in iread()] at the time
  49  * the signal is received, we call intread to interrupt the iread.
  50  */
  51
  52 #include <signal.h>
  53 #include <unistd.h>
  54
  55 #include "less.h"
  56 #include "extern.h"
  57
  58 /*
  59  * "sigs" contains bits indicating signals which need to be processed.
  60  */
  61 int sigs;
  62
  63 #ifdef SIGTSTP
  64 #define S_STOP          02
  65 #endif
  66 #if defined(SIGWINCH) || defined(SIGWIND)
  67 #define S_WINCH         04
  68 #endif
  69
  70
  71 static void purgeandquit __P((int));
  72
  73 #ifdef SIGTSTP
  74 static void stop __P((int));
  75 /*
  76  * "Stop" (^Z) signal handler.
  77  */
  78 static void
  79 stop(n)
  80         int n;
  81 {
  82         (void)signal(SIGTSTP, stop);
  83         sigs |= S_STOP;
  84         if (reading)
  85                 intread();
  86 }
  87 #endif
  88
  89 #ifdef SIGWINCH
  90 /*
  91  * "Window" change handler
  92  */
  93 void
  94 winch(n)
  95         int n;
  96 {
  97         (void)signal(SIGWINCH, winch);
  98         sigs |= S_WINCH;
  99         if (reading)
 100                 intread();
 101 }
 102 #else
 103 #ifdef SIGWIND
 104 /*
 105  * "Window" change handler
 106  */
 107 winch()
 108 {
 109         (void)signal(SIGWIND, winch);
 110         sigs |= S_WINCH;
 111         if (reading)
 112                 intread();
 113 }
 114 #endif
 115 #endif
 116
 117 static void
 118 purgeandquit(n)
 119         int n;
 120 {
 121
 122         purge();        /* purge buffered output */
 123         quit();
 124 }
 125
 126 /*
 127  * Set up the signal handlers.
 128  */
 129 void
 130 init_signals(on)
 131         int on;
 132 {
 133         if (on)
 134         {
 135                 /*
 136                  * Set signal handlers.
 137                  */
 138                 (void)signal(SIGINT, purgeandquit);
 139 #ifdef SIGTSTP
 140                 (void)signal(SIGTSTP, stop);
 141 #endif
 142 #ifdef SIGWINCH
 143                 (void)signal(SIGWINCH, winch);
 144 #else
 145 #ifdef SIGWIND
 146                 (void)signal(SIGWIND, winch);
 147 #endif
 148 #endif
 149         } else
 150         {
 151                 /*
 152                  * Restore signals to defaults.
 153                  */
 154                 (void)signal(SIGINT, SIG_DFL);
 155 #ifdef SIGTSTP
 156                 (void)signal(SIGTSTP, SIG_DFL);
 157 #endif
 158 #ifdef SIGWINCH
 159                 (void)signal(SIGWINCH, SIG_IGN);
 160 #endif
 161 #ifdef SIGWIND
 162                 (void)signal(SIGWIND, SIG_IGN);
 163 #endif
 164         }
 165 }
 166
 167 /*
 168  * Process any signals we have received.
 169  * A received signal cause a bit to be set in "sigs".
 170  */
 171 void
 172 psignals()
 173 {
 174         int tsignals;
 175
 176         if ((tsignals = sigs) == 0)
 177                 return;
 178         sigs = 0;
 179
 180 #ifdef S_WINCH
 181         if (tsignals & S_WINCH)
 182         {
 183                 int old_width, old_height;
 184                 /*
 185                  * Re-execute get_term() to read the new window size.
 186                  */
 187                 old_width = sc_width;
 188                 old_height = sc_height;
 189                 get_term();
 190                 if (sc_width != old_width || sc_height != old_height)
 191                 {
 192                         scroll_lines = (sc_height + 1) / 2;
 193                         screen_trashed = 1;
 194                 }
 195         }
 196 #endif
 197 #ifdef SIGTSTP
 198         if (tsignals & S_STOP)
 199         {
 200                 /*
 201                  * Clean up the terminal.
 202                  */
 203 #ifdef SIGTTOU
 204                 (void)signal(SIGTTOU, SIG_IGN);
 205 #endif
 206                 lower_left();
 207                 clear_eol();
 208                 deinit();
 209                 (void)flush();
 210                 raw_mode(0);
 211 #ifdef SIGTTOU
 212                 (void)signal(SIGTTOU, SIG_DFL);
 213 #endif
 214                 (void)signal(SIGTSTP, SIG_DFL);
 215                 (void)kill(getpid(), SIGTSTP);
 216                 /*
 217                  * ... Bye bye. ...
 218                  * Hopefully we'll be back later and resume here...
 219                  * Reset the terminal and arrange to repaint the
 220                  * screen when we get back to the main command loop.
 221                  */
 222                 (void)signal(SIGTSTP, stop);
 223                 raw_mode(1);
 224                 init();
 225                 screen_trashed = 1;
 226         }
 227 #endif
 228 }