contrib/texinfo-4/info/signals.c

   1 /* signals.c -- install and maintain signal handlers.
   2    $Id: signals.c,v 1.7 2004/04/11 17:56:46 karl Exp $
   3
   4    Copyright (C) 1993, 1994, 1995, 1998, 2002, 2003, 2004 Free Software
   5    Foundation, Inc.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2, or (at your option)
  10    any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  20
  21    Originally written by Brian Fox (bfox@ai.mit.edu). */
  22
  23 #include "info.h"
  24 #include "signals.h"
  25
  26 void initialize_info_signal_handler (void);
  27
  28 /* **************************************************************** */
  29 /*                                                                  */
  30 /*              Pretending That We Have POSIX Signals               */
  31 /*                                                                  */
  32 /* **************************************************************** */
  33
  34 #if !defined (HAVE_SIGPROCMASK) && defined (HAVE_SIGSETMASK)
  35 /* Perform OPERATION on NEWSET, perhaps leaving information in OLDSET. */
  36 static void
  37 sigprocmask (int operation, int *newset, int *oldset)
  38 {
  39   switch (operation)
  40     {
  41     case SIG_UNBLOCK:
  42       sigsetmask (sigblock (0) & ~(*newset));
  43       break;
  44
  45     case SIG_BLOCK:
  46       *oldset = sigblock (*newset);
  47       break;
  48
  49     case SIG_SETMASK:
  50       sigsetmask (*newset);
  51       break;
  52
  53     default:
  54       abort ();
  55     }
  56 }
  57 #endif /* !HAVE_SIGPROCMASK && HAVE_SIGSETMASK */
  58
  59 /* **************************************************************** */
  60 /*                                                                  */
  61 /*                  Signal Handling for Info                        */
  62 /*                                                                  */
  63 /* **************************************************************** */
  64
  65 #if defined (HAVE_SIGACTION) || defined (HAVE_SIGPROCMASK) ||\
  66   defined (HAVE_SIGSETMASK)
  67 static void
  68 mask_termsig (sigset_t *set)
  69 {
  70 # if defined (SIGTSTP)
  71   sigaddset (set, SIGTSTP);
  72   sigaddset (set, SIGTTOU);
  73   sigaddset (set, SIGTTIN);
  74 # endif
  75 # if defined (SIGWINCH)
  76   sigaddset (set, SIGWINCH);
  77 # endif
  78 #if defined (SIGQUIT)
  79   sigaddset (set, SIGQUIT);
  80 #endif
  81 #if defined (SIGINT)
  82   sigaddset (set, SIGINT);
  83 #endif
  84 # if defined (SIGUSR1)
  85   sigaddset (set, SIGUSR1);
  86 # endif
  87 }
  88 #endif /* HAVE_SIGACTION || HAVE_SIGPROCMASK || HAVE_SIGSETMASK */
  89
  90 static RETSIGTYPE info_signal_proc (int sig);
  91 #if defined (HAVE_SIGACTION)
  92 typedef struct sigaction signal_info;
  93 signal_info info_signal_handler;
  94
  95 static void
  96 set_termsig (int sig, signal_info *old)
  97 {
  98   sigaction (sig, &info_signal_handler, old);
  99 }
 100
 101 static void
 102 restore_termsig (int sig, const signal_info *saved)
 103 {
 104   sigaction (sig, saved, NULL);
 105 }
 106 #else /* !HAVE_SIGACTION */
 107 typedef RETSIGTYPE (*signal_info) ();
 108 #define set_termsig(sig, old) (void)(*(old) = signal (sig, info_signal_proc))
 109 #define restore_termsig(sig, saved) (void)signal (sig, *(saved))
 110 #define info_signal_handler info_signal_proc
 111 static int term_conf_busy = 0;
 112 #endif /* !HAVE_SIGACTION */
 113
 114 static signal_info old_TSTP, old_TTOU, old_TTIN;
 115 static signal_info old_WINCH, old_INT, old_USR1;
 116 static signal_info old_QUIT;
 117
 118 void
 119 initialize_info_signal_handler (void)
 120 {
 121 #ifdef SA_NOCLDSTOP
 122   /* (Based on info from Paul Eggert found in coreutils.)  Don't use
 123      HAVE_SIGACTION to decide whether to use the sa_handler, sa_flags,
 124      sa_mask members, as some systems (Solaris 7+) don't define them.  Use
 125      SA_NOCLDSTOP instead; it's been part of POSIX.1 since day 1 (in 1988).  */
 126   info_signal_handler.sa_handler = info_signal_proc;
 127   info_signal_handler.sa_flags = 0;
 128   mask_termsig (&info_signal_handler.sa_mask);
 129 #endif /* SA_NOCLDSTOP */
 130
 131 #if defined (SIGTSTP)
 132   set_termsig (SIGTSTP, &old_TSTP);
 133   set_termsig (SIGTTOU, &old_TTOU);
 134   set_termsig (SIGTTIN, &old_TTIN);
 135 #endif /* SIGTSTP */
 136
 137 #if defined (SIGWINCH)
 138   set_termsig (SIGWINCH, &old_WINCH);
 139 #endif
 140
 141 #if defined (SIGQUIT)
 142   set_termsig (SIGQUIT, &old_QUIT);
 143 #endif
 144
 145 #if defined (SIGINT)
 146   set_termsig (SIGINT, &old_INT);
 147 #endif
 148
 149 #if defined (SIGUSR1)
 150   /* Used by DJGPP to simulate SIGTSTP on Ctrl-Z.  */
 151   set_termsig (SIGUSR1, &old_USR1);
 152 #endif
 153 }
 154
 155 static void
 156 redisplay_after_signal (void)
 157 {
 158   terminal_clear_screen ();
 159   display_clear_display (the_display);
 160   window_mark_chain (windows, W_UpdateWindow);
 161   display_update_display (windows);
 162   display_cursor_at_point (active_window);
 163   fflush (stdout);
 164 }
 165
 166 static void
 167 reset_info_window_sizes (void)
 168 {
 169   terminal_goto_xy (0, 0);
 170   fflush (stdout);
 171   terminal_unprep_terminal ();
 172   terminal_get_screen_size ();
 173   terminal_prep_terminal ();
 174   display_initialize_display (screenwidth, screenheight);
 175   window_new_screen_size (screenwidth, screenheight);
 176   redisplay_after_signal ();
 177 }
 178
 179 static RETSIGTYPE
 180 info_signal_proc (int sig)
 181 {
 182   signal_info *old_signal_handler = NULL;
 183
 184 #if !defined (HAVE_SIGACTION)
 185   /* best effort: first increment this counter and later block signals */
 186   if (term_conf_busy)
 187     return;
 188   term_conf_busy++;
 189 #if defined (HAVE_SIGPROCMASK) || defined (HAVE_SIGSETMASK)
 190     {
 191       sigset_t nvar, ovar;
 192       sigemptyset (&nvar);
 193       mask_termsig (&nvar);
 194       sigprocmask (SIG_BLOCK, &nvar, &ovar);
 195     }
 196 #endif /* HAVE_SIGPROCMASK || HAVE_SIGSETMASK */
 197 #endif /* !HAVE_SIGACTION */
 198   switch (sig)
 199     {
 200 #if defined (SIGTSTP)
 201     case SIGTSTP:
 202     case SIGTTOU:
 203     case SIGTTIN:
 204 #endif
 205 #if defined (SIGQUIT)
 206     case SIGQUIT:
 207 #endif
 208 #if defined (SIGINT)
 209     case SIGINT:
 210 #endif
 211       {
 212 #if defined (SIGTSTP)
 213         if (sig == SIGTSTP)
 214           old_signal_handler = &old_TSTP;
 215         if (sig == SIGTTOU)
 216           old_signal_handler = &old_TTOU;
 217         if (sig == SIGTTIN)
 218           old_signal_handler = &old_TTIN;
 219 #endif /* SIGTSTP */
 220 #if defined (SIGQUIT)
 221         if (sig == SIGQUIT)
 222           old_signal_handler = &old_QUIT;
 223 #endif /* SIGQUIT */
 224 #if defined (SIGINT)
 225         if (sig == SIGINT)
 226           old_signal_handler = &old_INT;
 227 #endif /* SIGINT */
 228
 229         /* For stop signals, restore the terminal IO, leave the cursor
 230            at the bottom of the window, and stop us. */
 231         terminal_goto_xy (0, screenheight - 1);
 232         terminal_clear_to_eol ();
 233         fflush (stdout);
 234         terminal_unprep_terminal ();
 235         restore_termsig (sig, old_signal_handler);
 236         UNBLOCK_SIGNAL (sig);
 237         kill (getpid (), sig);
 238
 239         /* The program is returning now.  Restore our signal handler,
 240            turn on terminal handling, redraw the screen, and place the
 241            cursor where it belongs. */
 242         terminal_prep_terminal ();
 243         set_termsig (sig, old_signal_handler);
 244         /* window size might be changed while sleeping */
 245         reset_info_window_sizes ();
 246       }
 247       break;
 248
 249 #if defined (SIGWINCH) || defined (SIGUSR1)
 250 #ifdef SIGWINCH
 251     case SIGWINCH:
 252 #endif
 253 #ifdef SIGUSR1
 254     case SIGUSR1:
 255 #endif
 256       {
 257         /* Turn off terminal IO, tell our parent that the window has changed,
 258            then reinitialize the terminal and rebuild our windows. */
 259 #ifdef SIGWINCH
 260         if (sig == SIGWINCH)
 261           old_signal_handler = &old_WINCH;
 262 #endif
 263 #ifdef SIGUSR1
 264         if (sig == SIGUSR1)
 265           old_signal_handler = &old_USR1;
 266 #endif
 267         terminal_goto_xy (0, 0);
 268         fflush (stdout);
 269         terminal_unprep_terminal (); /* needless? */
 270         restore_termsig (sig, old_signal_handler);
 271         UNBLOCK_SIGNAL (sig);
 272         kill (getpid (), sig);
 273
 274         /* After our old signal handler returns... */
 275         set_termsig (sig, old_signal_handler); /* needless? */
 276         terminal_prep_terminal ();
 277         reset_info_window_sizes ();
 278       }
 279       break;
 280 #endif /* SIGWINCH || SIGUSR1 */
 281     }
 282 #if !defined (HAVE_SIGACTION)
 283   /* at this time it is safer to perform unblock after decrement */
 284   term_conf_busy--;
 285 #if defined (HAVE_SIGPROCMASK) || defined (HAVE_SIGSETMASK)
 286     {
 287       sigset_t nvar, ovar;
 288       sigemptyset (&nvar);
 289       mask_termsig (&nvar);
 290       sigprocmask (SIG_UNBLOCK, &nvar, &ovar);
 291     }
 292 #endif /* HAVE_SIGPROCMASK || HAVE_SIGSETMASK */
 293 #endif /* !HAVE_SIGACTION */
 294 }
 295 /* vim: set sw=2 cino={1s>2sn-s^-se-s: */