lib/readline/signals.c

   1 /* signals.c -- signal handling support for readline. */
   2
   3 /* Copyright (C) 1987, 1989, 1992 Free Software Foundation, Inc.
   4
   5    This file is part of the GNU Readline Library, a library for
   6    reading lines of text with interactive input and history editing.
   7
   8    The GNU Readline Library is free software; you can redistribute it
   9    and/or modify it under the terms of the GNU General Public License
  10    as published by the Free Software Foundation; either version 2, or
  11    (at your option) any later version.
  12
  13    The GNU Readline Library is distributed in the hope that it will be
  14    useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  15    of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    The GNU General Public License is often shipped with GNU software, and
  19    is generally kept in a file called COPYING or LICENSE.  If you do not
  20    have a copy of the license, write to the Free Software Foundation,
  21    59 Temple Place, Suite 330, Boston, MA 02111 USA. */
  22 #define READLINE_LIBRARY
  23
  24 #if defined (HAVE_CONFIG_H)
  25 #  include <config.h>
  26 #endif
  27
  28 #include <stdio.h>              /* Just for NULL.  Yuck. */
  29 #include <sys/types.h>
  30 #include <signal.h>
  31
  32 #if defined (HAVE_UNISTD_H)
  33 #  include <unistd.h>
  34 #endif /* HAVE_UNISTD_H */
  35
  36 /* System-specific feature definitions and include files. */
  37 #include "rldefs.h"
  38
  39 #if defined (GWINSZ_IN_SYS_IOCTL)
  40 #  include <sys/ioctl.h>
  41 #endif /* GWINSZ_IN_SYS_IOCTL */
  42
  43 #if defined (HANDLE_SIGNALS)
  44 /* Some standard library routines. */
  45 #include "readline.h"
  46 #include "history.h"
  47
  48 #include "rlprivate.h"
  49
  50 #if !defined (RETSIGTYPE)
  51 #  if defined (VOID_SIGHANDLER)
  52 #    define RETSIGTYPE void
  53 #  else
  54 #    define RETSIGTYPE int
  55 #  endif /* !VOID_SIGHANDLER */
  56 #endif /* !RETSIGTYPE */
  57
  58 #if defined (VOID_SIGHANDLER)
  59 #  define SIGHANDLER_RETURN return
  60 #else
  61 #  define SIGHANDLER_RETURN return (0)
  62 #endif
  63
  64 /* This typedef is equivalant to the one for Function; it allows us
  65    to say SigHandler *foo = signal (SIGKILL, SIG_IGN); */
  66 typedef RETSIGTYPE SigHandler ();
  67
  68 #if defined (HAVE_POSIX_SIGNALS)
  69 typedef struct sigaction sighandler_cxt;
  70 #  define rl_sigaction(s, nh, oh)       sigaction(s, nh, oh)
  71 #else
  72 typedef struct { SigHandler *sa_handler; int sa_mask, sa_flags; } sighandler_cxt;
  73 #  define sigemptyset(m)
  74 #endif /* !HAVE_POSIX_SIGNALS */
  75
  76 static SigHandler *rl_set_sighandler __P((int, SigHandler *, sighandler_cxt *));
  77
  78 /* Exported variables for use by applications. */
  79
  80 /* If non-zero, readline will install its own signal handlers for
  81    SIGINT, SIGTERM, SIGQUIT, SIGALRM, SIGTSTP, SIGTTIN, and SIGTTOU. */
  82 int rl_catch_signals = 1;
  83
  84 /* If non-zero, readline will install a signal handler for SIGWINCH. */
  85 #ifdef SIGWINCH
  86 int rl_catch_sigwinch = 1;
  87 #endif
  88
  89 static int signals_set_flag;
  90 static int sigwinch_set_flag;
  91
  92 /* **************************************************************** */
  93 /*                                                                  */
  94 /*                         Signal Handling                          */
  95 /*                                                                  */
  96 /* **************************************************************** */
  97
  98 static sighandler_cxt old_int, old_term, old_alrm, old_quit;
  99 #if defined (SIGTSTP)
 100 static sighandler_cxt old_tstp, old_ttou, old_ttin;
 101 #endif
 102 #if defined (SIGWINCH)
 103 static sighandler_cxt old_winch;
 104 #endif
 105
 106 /* Readline signal handler functions. */
 107
 108 static RETSIGTYPE
 109 rl_signal_handler (sig)
 110      int sig;
 111 {
 112 #if defined (HAVE_POSIX_SIGNALS)
 113   sigset_t set;
 114 #else /* !HAVE_POSIX_SIGNALS */
 115 #  if defined (HAVE_BSD_SIGNALS)
 116   long omask;
 117 #  else /* !HAVE_BSD_SIGNALS */
 118   sighandler_cxt dummy_cxt;     /* needed for rl_set_sighandler call */
 119 #  endif /* !HAVE_BSD_SIGNALS */
 120 #endif /* !HAVE_POSIX_SIGNALS */
 121
 122 #if !defined (HAVE_BSD_SIGNALS) && !defined (HAVE_POSIX_SIGNALS)
 123   /* Since the signal will not be blocked while we are in the signal
 124      handler, ignore it until rl_clear_signals resets the catcher. */
 125   if (sig == SIGINT || sig == SIGALRM)
 126     rl_set_sighandler (sig, SIG_IGN, &dummy_cxt);
 127 #endif /* !HAVE_BSD_SIGNALS && !HAVE_POSIX_SIGNALS */
 128
 129   switch (sig)
 130     {
 131     case SIGINT:
 132       rl_free_line_state ();
 133       /* FALLTHROUGH */
 134
 135 #if defined (SIGTSTP)
 136     case SIGTSTP:
 137     case SIGTTOU:
 138     case SIGTTIN:
 139 #endif /* SIGTSTP */
 140     case SIGALRM:
 141     case SIGTERM:
 142     case SIGQUIT:
 143       rl_cleanup_after_signal ();
 144
 145 #if defined (HAVE_POSIX_SIGNALS)
 146       sigprocmask (SIG_BLOCK, (sigset_t *)NULL, &set);
 147       sigdelset (&set, sig);
 148 #else /* !HAVE_POSIX_SIGNALS */
 149 #  if defined (HAVE_BSD_SIGNALS)
 150       omask = sigblock (0);
 151 #  endif /* HAVE_BSD_SIGNALS */
 152 #endif /* !HAVE_POSIX_SIGNALS */
 153
 154 #if defined (__EMX__)
 155       signal (sig, SIG_ACK);
 156 #endif
 157
 158       kill (getpid (), sig);
 159
 160       /* Let the signal that we just sent through.  */
 161 #if defined (HAVE_POSIX_SIGNALS)
 162       sigprocmask (SIG_SETMASK, &set, (sigset_t *)NULL);
 163 #else /* !HAVE_POSIX_SIGNALS */
 164 #  if defined (HAVE_BSD_SIGNALS)
 165       sigsetmask (omask & ~(sigmask (sig)));
 166 #  endif /* HAVE_BSD_SIGNALS */
 167 #endif /* !HAVE_POSIX_SIGNALS */
 168
 169       rl_reset_after_signal ();
 170     }
 171
 172   SIGHANDLER_RETURN;
 173 }
 174
 175 #if defined (SIGWINCH)
 176 static RETSIGTYPE
 177 rl_sigwinch_handler (sig)
 178      int sig;
 179 {
 180   SigHandler *oh;
 181
 182 #if defined (MUST_REINSTALL_SIGHANDLERS)
 183   sighandler_cxt dummy_winch;
 184
 185   /* We don't want to change old_winch -- it holds the state of SIGWINCH
 186      disposition set by the calling application.  We need this state
 187      because we call the application's SIGWINCH handler after updating
 188      our own idea of the screen size. */
 189   rl_set_sighandler (SIGWINCH, rl_sigwinch_handler, &dummy_winch);
 190 #endif
 191
 192   rl_resize_terminal ();
 193
 194   /* If another sigwinch handler has been installed, call it. */
 195   oh = (SigHandler *)old_winch.sa_handler;
 196   if (oh &&  oh != (SigHandler *)SIG_IGN && oh != (SigHandler *)SIG_DFL)
 197     (*oh) (sig);
 198
 199   SIGHANDLER_RETURN;
 200 }
 201 #endif  /* SIGWINCH */
 202
 203 /* Functions to manage signal handling. */
 204
 205 #if !defined (HAVE_POSIX_SIGNALS)
 206 static int
 207 rl_sigaction (sig, nh, oh)
 208      int sig;
 209      sighandler_cxt *nh, *oh;
 210 {
 211   oh->sa_handler = signal (sig, nh->sa_handler);
 212   return 0;
 213 }
 214 #endif /* !HAVE_POSIX_SIGNALS */
 215
 216 /* Set up a readline-specific signal handler, saving the old signal
 217    information in OHANDLER.  Return the old signal handler, like
 218    signal(). */
 219 static SigHandler *
 220 rl_set_sighandler (sig, handler, ohandler)
 221      int sig;
 222      SigHandler *handler;
 223      sighandler_cxt *ohandler;
 224 {
 225   sighandler_cxt old_handler;
 226 #if defined (HAVE_POSIX_SIGNALS)
 227   struct sigaction act;
 228
 229   act.sa_handler = handler;
 230   act.sa_flags = 0;
 231   sigemptyset (&act.sa_mask);
 232   sigemptyset (&ohandler->sa_mask);
 233   sigaction (sig, &act, &old_handler);
 234 #else
 235   old_handler.sa_handler = (SigHandler *)signal (sig, handler);
 236 #endif /* !HAVE_POSIX_SIGNALS */
 237
 238   /* XXX -- assume we have memcpy */
 239   /* If rl_set_signals is called twice in a row, don't set the old handler to
 240      rl_signal_handler, because that would cause infinite recursion. */
 241   if (handler != rl_signal_handler || old_handler.sa_handler != rl_signal_handler)
 242     memcpy (ohandler, &old_handler, sizeof (sighandler_cxt));
 243
 244   return (ohandler->sa_handler);
 245 }
 246
 247 static void
 248 rl_maybe_set_sighandler (sig, handler, ohandler)
 249      int sig;
 250      SigHandler *handler;
 251      sighandler_cxt *ohandler;
 252 {
 253   sighandler_cxt dummy;
 254   SigHandler *oh;
 255
 256   sigemptyset (&dummy.sa_mask);
 257   oh = rl_set_sighandler (sig, handler, ohandler);
 258   if (oh == (SigHandler *)SIG_IGN)
 259     rl_sigaction (sig, ohandler, &dummy);
 260 }
 261
 262 int
 263 rl_set_signals ()
 264 {
 265   sighandler_cxt dummy;
 266   SigHandler *oh;
 267
 268   if (rl_catch_signals && signals_set_flag == 0)
 269     {
 270       rl_maybe_set_sighandler (SIGINT, rl_signal_handler, &old_int);
 271       rl_maybe_set_sighandler (SIGTERM, rl_signal_handler, &old_term);
 272       rl_maybe_set_sighandler (SIGQUIT, rl_signal_handler, &old_quit);
 273
 274       oh = rl_set_sighandler (SIGALRM, rl_signal_handler, &old_alrm);
 275       if (oh == (SigHandler *)SIG_IGN)
 276         rl_sigaction (SIGALRM, &old_alrm, &dummy);
 277 #if defined (HAVE_POSIX_SIGNALS) && defined (SA_RESTART)
 278       /* If the application using readline has already installed a signal
 279          handler with SA_RESTART, SIGALRM will cause reads to be restarted
 280          automatically, so readline should just get out of the way.  Since
 281          we tested for SIG_IGN above, we can just test for SIG_DFL here. */
 282       if (oh != (SigHandler *)SIG_DFL && (old_alrm.sa_flags & SA_RESTART))
 283         rl_sigaction (SIGALRM, &old_alrm, &dummy);
 284 #endif /* HAVE_POSIX_SIGNALS */
 285
 286 #if defined (SIGTSTP)
 287       rl_maybe_set_sighandler (SIGTSTP, rl_signal_handler, &old_tstp);
 288 #endif /* SIGTSTP */
 289
 290 #if defined (SIGTTOU)
 291       rl_maybe_set_sighandler (SIGTTOU, rl_signal_handler, &old_ttou);
 292 #endif /* SIGTTOU */
 293
 294 #if defined (SIGTTIN)
 295       rl_maybe_set_sighandler (SIGTTIN, rl_signal_handler, &old_ttin);
 296 #endif /* SIGTTIN */
 297
 298       signals_set_flag = 1;
 299     }
 300
 301 #if defined (SIGWINCH)
 302   if (rl_catch_sigwinch && sigwinch_set_flag == 0)
 303     {
 304       rl_maybe_set_sighandler (SIGWINCH, rl_sigwinch_handler, &old_winch);
 305       sigwinch_set_flag = 1;
 306     }
 307 #endif /* SIGWINCH */
 308
 309   return 0;
 310 }
 311
 312 int
 313 rl_clear_signals ()
 314 {
 315   sighandler_cxt dummy;
 316
 317   if (rl_catch_signals && signals_set_flag == 1)
 318     {
 319       sigemptyset (&dummy.sa_mask);
 320
 321       rl_sigaction (SIGINT, &old_int, &dummy);
 322       rl_sigaction (SIGTERM, &old_term, &dummy);
 323       rl_sigaction (SIGQUIT, &old_quit, &dummy);
 324       rl_sigaction (SIGALRM, &old_alrm, &dummy);
 325
 326 #if defined (SIGTSTP)
 327       rl_sigaction (SIGTSTP, &old_tstp, &dummy);
 328 #endif /* SIGTSTP */
 329
 330 #if defined (SIGTTOU)
 331       rl_sigaction (SIGTTOU, &old_ttou, &dummy);
 332 #endif /* SIGTTOU */
 333
 334 #if defined (SIGTTIN)
 335       rl_sigaction (SIGTTIN, &old_ttin, &dummy);
 336 #endif /* SIGTTIN */
 337
 338       signals_set_flag = 0;
 339     }
 340
 341 #if defined (SIGWINCH)
 342   if (rl_catch_sigwinch && sigwinch_set_flag == 1)
 343     {
 344       sigemptyset (&dummy.sa_mask);
 345       rl_sigaction (SIGWINCH, &old_winch, &dummy);
 346       sigwinch_set_flag = 0;
 347     }
 348 #endif
 349
 350   return 0;
 351 }
 352
 353 /* Clean up the terminal and readline state after catching a signal, before
 354    resending it to the calling application. */
 355 void
 356 rl_cleanup_after_signal ()
 357 {
 358   _rl_clean_up_for_exit ();
 359   (*rl_deprep_term_function) ();
 360   rl_clear_signals ();
 361   rl_pending_input = 0;
 362 }
 363
 364 /* Reset the terminal and readline state after a signal handler returns. */
 365 void
 366 rl_reset_after_signal ()
 367 {
 368   (*rl_prep_term_function) (_rl_meta_flag);
 369   rl_set_signals ();
 370 }
 371
 372 /* Free up the readline variable line state for the current line (undo list,
 373    any partial history entry, any keyboard macros in progress, and any
 374    numeric arguments in process) after catching a signal, before calling
 375    rl_cleanup_after_signal(). */
 376 void
 377 rl_free_line_state ()
 378 {
 379   register HIST_ENTRY *entry;
 380
 381   free_undo_list ();
 382
 383   entry = current_history ();
 384   if (entry)
 385     entry->data = (char *)NULL;
 386
 387   _rl_kill_kbd_macro ();
 388   rl_clear_message ();
 389   _rl_init_argument ();
 390 }
 391
 392 #endif  /* HANDLE_SIGNALS */