contrib/less/signal.c

   1 /*
   2  * Copyright (C) 1984-2015  Mark Nudelman
   3  *
   4  * You may distribute under the terms of either the GNU General Public
   5  * License or the Less License, as specified in the README file.
   6  *
   7  * For more information, see the README file.
   8  */
   9
  10
  11 /*
  12  * Routines dealing with signals.
  13  *
  14  * A signal usually merely causes a bit to be set in the "signals" word.
  15  * At some convenient time, the mainline code checks to see if any
  16  * signals need processing by calling psignal().
  17  * If we happen to be reading from a file [in iread()] at the time
  18  * the signal is received, we call intread to interrupt the iread.
  19  */
  20
  21 #include "less.h"
  22 #include <signal.h>
  23
  24 /*
  25  * "sigs" contains bits indicating signals which need to be processed.
  26  */
  27 public int sigs;
  28
  29 extern int sc_width, sc_height;
  30 extern int screen_trashed;
  31 extern int lnloop;
  32 extern int linenums;
  33 extern int wscroll;
  34 extern int reading;
  35 extern int quit_on_intr;
  36 extern long jump_sline_fraction;
  37
  38 /*
  39  * Interrupt signal handler.
  40  */
  41         /* ARGSUSED*/
  42         static RETSIGTYPE
  43 u_interrupt(type)
  44         int type;
  45 {
  46         bell();
  47 #if OS2
  48         LSIGNAL(SIGINT, SIG_ACK);
  49 #endif
  50         LSIGNAL(SIGINT, u_interrupt);
  51         sigs |= S_INTERRUPT;
  52 #if MSDOS_COMPILER==DJGPPC
  53         /*
  54          * If a keyboard has been hit, it must be Ctrl-C
  55          * (as opposed to Ctrl-Break), so consume it.
  56          * (Otherwise, Less will beep when it sees Ctrl-C from keyboard.)
  57          */
  58         if (kbhit())
  59                 getkey();
  60 #endif
  61         if (reading)
  62                 intread(); /* May longjmp */
  63 }
  64
  65 #ifdef SIGTSTP
  66 /*
  67  * "Stop" (^Z) signal handler.
  68  */
  69         /* ARGSUSED*/
  70         static RETSIGTYPE
  71 stop(type)
  72         int type;
  73 {
  74         LSIGNAL(SIGTSTP, stop);
  75         sigs |= S_STOP;
  76         if (reading)
  77                 intread();
  78 }
  79 #endif
  80
  81 #ifdef SIGWINCH
  82 /*
  83  * "Window" change handler
  84  */
  85         /* ARGSUSED*/
  86         public RETSIGTYPE
  87 winch(type)
  88         int type;
  89 {
  90         LSIGNAL(SIGWINCH, winch);
  91         sigs |= S_WINCH;
  92         if (reading)
  93                 intread();
  94 }
  95 #else
  96 #ifdef SIGWIND
  97 /*
  98  * "Window" change handler
  99  */
 100         /* ARGSUSED*/
 101         public RETSIGTYPE
 102 winch(type)
 103         int type;
 104 {
 105         LSIGNAL(SIGWIND, winch);
 106         sigs |= S_WINCH;
 107         if (reading)
 108                 intread();
 109 }
 110 #endif
 111 #endif
 112
 113 #if MSDOS_COMPILER==WIN32C
 114 /*
 115  * Handle CTRL-C and CTRL-BREAK keys.
 116  */
 117 #include "windows.h"
 118
 119         static BOOL WINAPI
 120 wbreak_handler(dwCtrlType)
 121         DWORD dwCtrlType;
 122 {
 123         switch (dwCtrlType)
 124         {
 125         case CTRL_C_EVENT:
 126         case CTRL_BREAK_EVENT:
 127                 sigs |= S_INTERRUPT;
 128                 return (TRUE);
 129         default:
 130                 break;
 131         }
 132         return (FALSE);
 133 }
 134 #endif
 135
 136 /*
 137  * Set up the signal handlers.
 138  */
 139         public void
 140 init_signals(on)
 141         int on;
 142 {
 143         if (on)
 144         {
 145                 /*
 146                  * Set signal handlers.
 147                  */
 148                 (void) LSIGNAL(SIGINT, u_interrupt);
 149 #if MSDOS_COMPILER==WIN32C
 150                 SetConsoleCtrlHandler(wbreak_handler, TRUE);
 151 #endif
 152 #ifdef SIGTSTP
 153                 (void) LSIGNAL(SIGTSTP, stop);
 154 #endif
 155 #ifdef SIGWINCH
 156                 (void) LSIGNAL(SIGWINCH, winch);
 157 #endif
 158 #ifdef SIGWIND
 159                 (void) LSIGNAL(SIGWIND, winch);
 160 #endif
 161 #ifdef SIGQUIT
 162                 (void) LSIGNAL(SIGQUIT, SIG_IGN);
 163 #endif
 164         } else
 165         {
 166                 /*
 167                  * Restore signals to defaults.
 168                  */
 169                 (void) LSIGNAL(SIGINT, SIG_DFL);
 170 #if MSDOS_COMPILER==WIN32C
 171                 SetConsoleCtrlHandler(wbreak_handler, FALSE);
 172 #endif
 173 #ifdef SIGTSTP
 174                 (void) LSIGNAL(SIGTSTP, SIG_DFL);
 175 #endif
 176 #ifdef SIGWINCH
 177                 (void) LSIGNAL(SIGWINCH, SIG_IGN);
 178 #endif
 179 #ifdef SIGWIND
 180                 (void) LSIGNAL(SIGWIND, SIG_IGN);
 181 #endif
 182 #ifdef SIGQUIT
 183                 (void) LSIGNAL(SIGQUIT, SIG_DFL);
 184 #endif
 185         }
 186 }
 187
 188 /*
 189  * Process any signals we have received.
 190  * A received signal cause a bit to be set in "sigs".
 191  */
 192         public void
 193 psignals()
 194 {
 195         register int tsignals;
 196
 197         if ((tsignals = sigs) == 0)
 198                 return;
 199         sigs = 0;
 200
 201 #ifdef SIGTSTP
 202         if (tsignals & S_STOP)
 203         {
 204                 /*
 205                  * Clean up the terminal.
 206                  */
 207 #ifdef SIGTTOU
 208                 LSIGNAL(SIGTTOU, SIG_IGN);
 209 #endif
 210                 clear_bot();
 211                 deinit();
 212                 flush();
 213                 raw_mode(0);
 214 #ifdef SIGTTOU
 215                 LSIGNAL(SIGTTOU, SIG_DFL);
 216 #endif
 217                 LSIGNAL(SIGTSTP, SIG_DFL);
 218                 kill(getpid(), SIGTSTP);
 219                 /*
 220                  * ... Bye bye. ...
 221                  * Hopefully we'll be back later and resume here...
 222                  * Reset the terminal and arrange to repaint the
 223                  * screen when we get back to the main command loop.
 224                  */
 225                 LSIGNAL(SIGTSTP, stop);
 226                 raw_mode(1);
 227                 init();
 228                 screen_trashed = 1;
 229                 tsignals |= S_WINCH;
 230         }
 231 #endif
 232 #ifdef S_WINCH
 233         if (tsignals & S_WINCH)
 234         {
 235                 int old_width, old_height;
 236                 /*
 237                  * Re-execute scrsize() to read the new window size.
 238                  */
 239                 old_width = sc_width;
 240                 old_height = sc_height;
 241                 get_term();
 242                 if (sc_width != old_width || sc_height != old_height)
 243                 {
 244                         wscroll = (sc_height + 1) / 2;
 245                         calc_jump_sline();
 246                         calc_shift_count();
 247                         screen_trashed = 1;
 248                 }
 249         }
 250 #endif
 251         if (tsignals & S_INTERRUPT)
 252         {
 253                 if (quit_on_intr)
 254                         quit(QUIT_INTERRUPT);
 255         }
 256 }