contrib/less/signal.c

   1 /*
   2  * Copyright (C) 1984-2009  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 about less, or for information on how to
   8  * contact the author, see the README file.
   9  */
  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  * If we happen to be reading from a file [in iread()] at the time
  19  * the signal is received, we call intread to interrupt the iread.
  20  */
  21
  22 #include "less.h"
  23 #include <signal.h>
  24
  25 /*
  26  * "sigs" contains bits indicating signals which need to be processed.
  27  */
  28 public int sigs;
  29
  30 extern int sc_width, sc_height;
  31 extern int screen_trashed;
  32 extern int lnloop;
  33 extern int linenums;
  34 extern int wscroll;
  35 extern int reading;
  36 extern int quit_on_intr;
  37 extern long jump_sline_fraction;
  38
  39 /*
  40  * Interrupt signal handler.
  41  */
  42         /* ARGSUSED*/
  43         static RETSIGTYPE
  44 u_interrupt(type)
  45         int type;
  46 {
  47         bell();
  48 #if OS2
  49         LSIGNAL(SIGINT, SIG_ACK);
  50 #endif
  51         LSIGNAL(SIGINT, u_interrupt);
  52         sigs |= S_INTERRUPT;
  53 #if MSDOS_COMPILER==DJGPPC
  54         /*
  55          * If a keyboard has been hit, it must be Ctrl-C
  56          * (as opposed to Ctrl-Break), so consume it.
  57          * (Otherwise, Less will beep when it sees Ctrl-C from keyboard.)
  58          */
  59         if (kbhit())
  60                 getkey();
  61 #endif
  62         if (reading)
  63                 intread(); /* May longjmp */
  64 }
  65
  66 #ifdef SIGTSTP
  67 /*
  68  * "Stop" (^Z) signal handler.
  69  */
  70         /* ARGSUSED*/
  71         static RETSIGTYPE
  72 stop(type)
  73         int type;
  74 {
  75         LSIGNAL(SIGTSTP, stop);
  76         sigs |= S_STOP;
  77         if (reading)
  78                 intread();
  79 }
  80 #endif
  81
  82 #ifdef SIGWINCH
  83 /*
  84  * "Window" change handler
  85  */
  86         /* ARGSUSED*/
  87         public RETSIGTYPE
  88 winch(type)
  89         int type;
  90 {
  91         LSIGNAL(SIGWINCH, winch);
  92         sigs |= S_WINCH;
  93         if (reading)
  94                 intread();
  95 }
  96 #else
  97 #ifdef SIGWIND
  98 /*
  99  * "Window" change handler
 100  */
 101         /* ARGSUSED*/
 102         public RETSIGTYPE
 103 winch(type)
 104         int type;
 105 {
 106         LSIGNAL(SIGWIND, winch);
 107         sigs |= S_WINCH;
 108         if (reading)
 109                 intread();
 110 }
 111 #endif
 112 #endif
 113
 114 #if MSDOS_COMPILER==WIN32C
 115 /*
 116  * Handle CTRL-C and CTRL-BREAK keys.
 117  */
 118 #include "windows.h"
 119
 120         static BOOL WINAPI
 121 wbreak_handler(dwCtrlType)
 122         DWORD dwCtrlType;
 123 {
 124         switch (dwCtrlType)
 125         {
 126         case CTRL_C_EVENT:
 127         case CTRL_BREAK_EVENT:
 128                 sigs |= S_INTERRUPT;
 129                 return (TRUE);
 130         default:
 131                 break;
 132         }
 133         return (FALSE);
 134 }
 135 #endif
 136
 137 /*
 138  * Set up the signal handlers.
 139  */
 140         public void
 141 init_signals(on)
 142         int on;
 143 {
 144         if (on)
 145         {
 146                 /*
 147                  * Set signal handlers.
 148                  */
 149                 (void) LSIGNAL(SIGINT, u_interrupt);
 150 #if MSDOS_COMPILER==WIN32C
 151                 SetConsoleCtrlHandler(wbreak_handler, TRUE);
 152 #endif
 153 #ifdef SIGTSTP
 154                 (void) LSIGNAL(SIGTSTP, stop);
 155 #endif
 156 #ifdef SIGWINCH
 157                 (void) LSIGNAL(SIGWINCH, winch);
 158 #endif
 159 #ifdef SIGWIND
 160                 (void) LSIGNAL(SIGWIND, winch);
 161 #endif
 162 #ifdef SIGQUIT
 163                 (void) LSIGNAL(SIGQUIT, SIG_IGN);
 164 #endif
 165         } else
 166         {
 167                 /*
 168                  * Restore signals to defaults.
 169                  */
 170                 (void) LSIGNAL(SIGINT, SIG_DFL);
 171 #if MSDOS_COMPILER==WIN32C
 172                 SetConsoleCtrlHandler(wbreak_handler, FALSE);
 173 #endif
 174 #ifdef SIGTSTP
 175                 (void) LSIGNAL(SIGTSTP, SIG_DFL);
 176 #endif
 177 #ifdef SIGWINCH
 178                 (void) LSIGNAL(SIGWINCH, SIG_IGN);
 179 #endif
 180 #ifdef SIGWIND
 181                 (void) LSIGNAL(SIGWIND, SIG_IGN);
 182 #endif
 183 #ifdef SIGQUIT
 184                 (void) LSIGNAL(SIGQUIT, SIG_DFL);
 185 #endif
 186         }
 187 }
 188
 189 /*
 190  * Process any signals we have received.
 191  * A received signal cause a bit to be set in "sigs".
 192  */
 193         public void
 194 psignals()
 195 {
 196         register int tsignals;
 197
 198         if ((tsignals = sigs) == 0)
 199                 return;
 200         sigs = 0;
 201
 202 #ifdef SIGTSTP
 203         if (tsignals & S_STOP)
 204         {
 205                 /*
 206                  * Clean up the terminal.
 207                  */
 208 #ifdef SIGTTOU
 209                 LSIGNAL(SIGTTOU, SIG_IGN);
 210 #endif
 211                 clear_bot();
 212                 deinit();
 213                 flush();
 214                 raw_mode(0);
 215 #ifdef SIGTTOU
 216                 LSIGNAL(SIGTTOU, SIG_DFL);
 217 #endif
 218                 LSIGNAL(SIGTSTP, SIG_DFL);
 219                 kill(getpid(), SIGTSTP);
 220                 /*
 221                  * ... Bye bye. ...
 222                  * Hopefully we'll be back later and resume here...
 223                  * Reset the terminal and arrange to repaint the
 224                  * screen when we get back to the main command loop.
 225                  */
 226                 LSIGNAL(SIGTSTP, stop);
 227                 raw_mode(1);
 228                 init();
 229                 screen_trashed = 1;
 230                 tsignals |= S_WINCH;
 231         }
 232 #endif
 233 #ifdef S_WINCH
 234         if (tsignals & S_WINCH)
 235         {
 236                 int old_width, old_height;
 237                 /*
 238                  * Re-execute scrsize() to read the new window size.
 239                  */
 240                 old_width = sc_width;
 241                 old_height = sc_height;
 242                 get_term();
 243                 if (sc_width != old_width || sc_height != old_height)
 244                 {
 245                         wscroll = (sc_height + 1) / 2;
 246                         calc_jump_sline();
 247                         calc_shift_count();
 248                         screen_trashed = 1;
 249                 }
 250         }
 251 #endif
 252         if (tsignals & S_INTERRUPT)
 253         {
 254                 if (quit_on_intr)
 255                         quit(QUIT_OK);
 256         }
 257 }