bin/less/signal.c

   1 /*
   2  * Copyright (C) 1984-2012  Mark Nudelman
   3  * Modified for use with illumos by Garrett D'Amore.
   4  * Copyright 2015 Garrett D'Amore <garrett@damore.org>
   5  *
   6  * You may distribute under the terms of either the GNU General Public
   7  * License or the Less License, as specified in the README file.
   8  *
   9  * For more information, see the README file.
  10  */
  11
  12 /*
  13  * Routines dealing with signals.
  14  *
  15  * A signal usually merely causes a bit to be set in the "signals" word.
  16  * At some convenient time, the mainline code checks to see if any
  17  * signals need processing by calling psignal().
  18  */
  19
  20 #include <signal.h>
  21
  22 #include "less.h"
  23
  24 /*
  25  * "sigs" contains bits indicating signals which need to be processed.
  26  */
  27 volatile sig_atomic_t sigs;
  28
  29 extern int sc_width, sc_height;
  30 extern int screen_trashed;
  31 extern int linenums;
  32 extern int wscroll;
  33 extern int quit_on_intr;
  34 extern long jump_sline_fraction;
  35
  36 /*
  37  * Interrupt signal handler.
  38  */
  39 static void
  40 u_interrupt(int type)
  41 {
  42         sigs |= S_INTERRUPT;
  43 }
  44
  45 /*
  46  * "Stop" (^Z) signal handler.
  47  */
  48 static void
  49 stop(int type)
  50 {
  51         sigs |= S_STOP;
  52 }
  53
  54 /*
  55  * "Window" change handler
  56  */
  57 void
  58 sigwinch(int type)
  59 {
  60         sigs |= S_WINCH;
  61 }
  62
  63 /*
  64  * Set up the signal handlers.
  65  */
  66 void
  67 init_signals(int on)
  68 {
  69         if (on) {
  70                 /*
  71                  * Set signal handlers.
  72                  */
  73                 (void) lsignal(SIGINT, u_interrupt);
  74                 (void) lsignal(SIGTSTP, stop);
  75                 (void) lsignal(SIGWINCH, sigwinch);
  76                 (void) lsignal(SIGQUIT, SIG_IGN);
  77         } else {
  78                 /*
  79                  * Restore signals to defaults.
  80                  */
  81                 (void) lsignal(SIGINT, SIG_DFL);
  82                 (void) lsignal(SIGTSTP, SIG_DFL);
  83                 (void) lsignal(SIGWINCH, SIG_IGN);
  84                 (void) lsignal(SIGQUIT, SIG_DFL);
  85         }
  86 }
  87
  88 /*
  89  * Process any signals we have received.
  90  * A received signal cause a bit to be set in "sigs".
  91  */
  92 void
  93 psignals(void)
  94 {
  95         int tsignals;
  96
  97         if ((tsignals = sigs) == 0)
  98                 return;
  99         sigs = 0;
 100
 101         if (tsignals & S_STOP) {
 102                 /*
 103                  * Clean up the terminal.
 104                  */
 105                 lsignal(SIGTTOU, SIG_IGN);
 106                 clear_bot();
 107                 deinit();
 108                 flush(0);
 109                 raw_mode(0);
 110                 lsignal(SIGTTOU, SIG_DFL);
 111                 lsignal(SIGTSTP, SIG_DFL);
 112                 kill(getpid(), SIGTSTP);
 113                 /*
 114                  * ... Bye bye. ...
 115                  * Hopefully we'll be back later and resume here...
 116                  * Reset the terminal and arrange to repaint the
 117                  * screen when we get back to the main command loop.
 118                  */
 119                 lsignal(SIGTSTP, stop);
 120                 raw_mode(1);
 121                 init();
 122                 screen_trashed = 1;
 123                 tsignals |= S_WINCH;
 124         }
 125         if (tsignals & S_WINCH) {
 126                 int old_width, old_height;
 127                 /*
 128                  * Re-execute scrsize() to read the new window size.
 129                  */
 130                 old_width = sc_width;
 131                 old_height = sc_height;
 132                 get_term();
 133                 if (sc_width != old_width || sc_height != old_height) {
 134                         wscroll = (sc_height + 1) / 2;
 135                         calc_jump_sline();
 136                         calc_shift_count();
 137                         screen_trashed = 1;
 138                 }
 139         }
 140         if (tsignals & S_INTERRUPT) {
 141                 ring_bell();
 142                 if (quit_on_intr)
 143                         quit(QUIT_INTERRUPT);
 144         }
 145 }
 146
 147 /*
 148  * Custom version of signal() that causes syscalls to be interrupted.
 149  */
 150 void *
 151 lsignal(int s, void (*a)(int))
 152 {
 153         struct sigaction sa, osa;
 154
 155         sa.sa_handler = a;
 156         sigemptyset(&sa.sa_mask);
 157         sa.sa_flags = 0;                /* don't restart system calls */
 158         if (sigaction(s, &sa, &osa) != 0)
 159                 return (SIG_ERR);
 160         return (osa.sa_handler);
 161 }