text: /* signals.c -- signal handling support for readline. */
  
  /* Copyright (C) 1987-2005 Free Software Foundation, Inc.
  
     This file is part of the GNU Readline Library, a library for
     reading lines of text with interactive input and history editing.
  
     The GNU Readline Library is free software; you can redistribute it
     and/or modify it under the terms of the GNU General Public License
     as published by the Free Software Foundation; either version 2, or
     (at your option) any later version.
  
     The GNU Readline Library is distributed in the hope that it will be
     useful, but WITHOUT ANY WARRANTY; without even the implied warranty
     of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
  
     The GNU General Public License is often shipped with GNU software, and
     is generally kept in a file called COPYING or LICENSE.  If you do not
     have a copy of the license, write to the Free Software Foundation,
     51 Franklin Street, Fifth Floor, Boston, MA  02110-1335  USA. */
  #define READLINE_LIBRARY
  
  #if defined (HAVE_CONFIG_H)
  #  include "config_readline.h"
  #endif
  
  #include <stdio.h>		/* Just for NULL.  Yuck. */
  #include <sys/types.h>
  #include <signal.h>
  
  #if defined (HAVE_UNISTD_H)
  #  include <unistd.h>
  #endif /* HAVE_UNISTD_H */
  
  /* System-specific feature definitions and include files. */
  #include "rldefs.h"
  
  #if defined (GWINSZ_IN_SYS_IOCTL)
  #  include <sys/ioctl.h>
  #endif /* GWINSZ_IN_SYS_IOCTL */
  
  #if defined (HANDLE_SIGNALS)
  /* Some standard library routines. */
  #include "readline.h"
  #include "history.h"
  
  #include "rlprivate.h"
  
  #if !defined (RETSIGTYPE)
  #  if defined (VOID_SIGHANDLER)
  #    define RETSIGTYPE void
  #  else
  #    define RETSIGTYPE int
  #  endif /* !VOID_SIGHANDLER */
  #endif /* !RETSIGTYPE */
  
  #if defined (VOID_SIGHANDLER)
  #  define SIGHANDLER_RETURN return
  #else
  #  define SIGHANDLER_RETURN return (0)
  #endif
  
  /* This typedef is equivalent to the one for Function; it allows us
     to say SigHandler *foo = signal (SIGKILL, SIG_IGN); */
  typedef RETSIGTYPE SigHandler ();
  
  #if defined (HAVE_POSIX_SIGNALS)
  typedef struct sigaction sighandler_cxt;
  #  define rl_sigaction(s, nh, oh)	sigaction(s, nh, oh)
  #else
  typedef struct { SigHandler *sa_handler; int sa_mask, sa_flags; } sighandler_cxt;
  #  define sigemptyset(m)
  #endif /* !HAVE_POSIX_SIGNALS */
  
  #ifndef SA_RESTART
  #  define SA_RESTART 0
  #endif
  
  static SigHandler *rl_set_sighandler PARAMS((int, SigHandler *, sighandler_cxt *));
  static void rl_maybe_set_sighandler PARAMS((int, SigHandler *, sighandler_cxt *));
  
  /* Exported variables for use by applications. */
  
  /* If non-zero, readline will install its own signal handlers for
     SIGINT, SIGTERM, SIGQUIT, SIGALRM, SIGTSTP, SIGTTIN, and SIGTTOU. */
  int rl_catch_signals = 1;
  
  /* If non-zero, readline will install a signal handler for SIGWINCH. */
  #ifdef SIGWINCH
  int rl_catch_sigwinch = 1;
  #else
  int rl_catch_sigwinch = 0;	/* for the readline state struct in readline.c */
  #endif
  
  static int signals_set_flag;
  static int sigwinch_set_flag;
  
  /* **************************************************************** */
  /*					        		    */
  /*			   Signal Handling                          */
  /*								    */
  /* **************************************************************** */
  
  static sighandler_cxt old_int, old_term, old_alrm, old_quit;
  #if defined (SIGTSTP)
  static sighandler_cxt old_tstp, old_ttou, old_ttin;
  #endif
  #if defined (SIGWINCH)
  static sighandler_cxt old_winch;
  #endif
  
  /* Readline signal handler functions. */
  
  static RETSIGTYPE
  rl_signal_handler (sig)
       int sig;
  {
  #if defined (HAVE_POSIX_SIGNALS)
    sigset_t set;
  #else /* !HAVE_POSIX_SIGNALS */
  #  if defined (HAVE_BSD_SIGNALS)
    long omask;
  #  else /* !HAVE_BSD_SIGNALS */
    sighandler_cxt dummy_cxt;	/* needed for rl_set_sighandler call */
  #  endif /* !HAVE_BSD_SIGNALS */
  #endif /* !HAVE_POSIX_SIGNALS */
  
    RL_SETSTATE(RL_STATE_SIGHANDLER);
  
  #if !defined (HAVE_BSD_SIGNALS) && !defined (HAVE_POSIX_SIGNALS)
    /* Since the signal will not be blocked while we are in the signal
       handler, ignore it until rl_clear_signals resets the catcher. */
  #  if defined (SIGALRM)
    if (sig == SIGINT || sig == SIGALRM)
  #  else
    if (sig == SIGINT)
  #  endif
      rl_set_sighandler (sig, SIG_IGN, &dummy_cxt);
  #endif /* !HAVE_BSD_SIGNALS && !HAVE_POSIX_SIGNALS */
  
    switch (sig)
      {
      case SIGINT:
        rl_free_line_state ();
        /* FALLTHROUGH */
  
      case SIGTERM:
  #if defined (SIGTSTP)
      case SIGTSTP:
      case SIGTTOU:
      case SIGTTIN:
  #endif /* SIGTSTP */
  #if defined (SIGALRM)
      case SIGALRM:
  #endif
  #if defined (SIGQUIT)
      case SIGQUIT:
  #endif
        rl_cleanup_after_signal ();
  
  #if defined (HAVE_POSIX_SIGNALS)
        sigemptyset (&set);
        sigprocmask (SIG_BLOCK, (sigset_t *)NULL, &set);
        sigdelset (&set, sig);
  #else /* !HAVE_POSIX_SIGNALS */
  #  if defined (HAVE_BSD_SIGNALS)
        omask = sigblock (0);
  #  endif /* HAVE_BSD_SIGNALS */
  #endif /* !HAVE_POSIX_SIGNALS */
  
  #if defined (__EMX__)
        signal (sig, SIG_ACK);
  #endif
  
  #if defined (HAVE_KILL)
        kill (getpid (), sig);
  #else
        raise (sig);		/* assume we have raise */
  #endif
  
        /* Let the signal that we just sent through.  */
  #if defined (HAVE_POSIX_SIGNALS)
        sigprocmask (SIG_SETMASK, &set, (sigset_t *)NULL);
  #else /* !HAVE_POSIX_SIGNALS */
  #  if defined (HAVE_BSD_SIGNALS)
        sigsetmask (omask & ~(sigmask (sig)));
  #  endif /* HAVE_BSD_SIGNALS */
  #endif /* !HAVE_POSIX_SIGNALS */
  
        rl_reset_after_signal ();
      }
  
    RL_UNSETSTATE(RL_STATE_SIGHANDLER);
    SIGHANDLER_RETURN;
  }
  
  #if defined (SIGWINCH)
  static RETSIGTYPE
  rl_sigwinch_handler (sig)
       int sig;
  {
    SigHandler *oh;
  
  #if defined (MUST_REINSTALL_SIGHANDLERS)
    sighandler_cxt dummy_winch;
  
    /* We don't want to change old_winch -- it holds the state of SIGWINCH
       disposition set by the calling application.  We need this state
       because we call the application's SIGWINCH handler after updating
       our own idea of the screen size. */
    rl_set_sighandler (SIGWINCH, rl_sigwinch_handler, &dummy_winch);
  #endif
  
    RL_SETSTATE(RL_STATE_SIGHANDLER);
    rl_resize_terminal ();
  
    /* If another sigwinch handler has been installed, call it. */
    oh = (SigHandler *)old_winch.sa_handler;
    if (oh &&  oh != (SigHandler *)SIG_IGN && oh != (SigHandler *)SIG_DFL)
      (*oh) (sig);
  
    RL_UNSETSTATE(RL_STATE_SIGHANDLER);
    SIGHANDLER_RETURN;
  }
  #endif  /* SIGWINCH */
  
  /* Functions to manage signal handling. */
  
  #if !defined (HAVE_POSIX_SIGNALS)
  static int
  rl_sigaction (sig, nh, oh)
       int sig;
       sighandler_cxt *nh, *oh;
  {
    oh->sa_handler = signal (sig, nh->sa_handler);
    return 0;
  }
  #endif /* !HAVE_POSIX_SIGNALS */
  
  /* Set up a readline-specific signal handler, saving the old signal
     information in OHANDLER.  Return the old signal handler, like
     signal(). */
  static SigHandler *
  rl_set_sighandler (sig, handler, ohandler)
       int sig;
       SigHandler *handler;
       sighandler_cxt *ohandler;
  {
    sighandler_cxt old_handler;
  #if defined (HAVE_POSIX_SIGNALS)
    struct sigaction act;
  
    act.sa_handler = handler;
    act.sa_flags = (sig == SIGWINCH) ? SA_RESTART : 0;
    sigemptyset (&act.sa_mask);
    sigemptyset (&ohandler->sa_mask);
    sigaction (sig, &act, &old_handler);
  #else
    old_handler.sa_handler = (SigHandler *)signal (sig, handler);
  #endif /* !HAVE_POSIX_SIGNALS */
  
    /* XXX -- assume we have memcpy */
    /* If rl_set_signals is called twice in a row, don't set the old handler to
       rl_signal_handler, because that would cause infinite recursion. */
    if (handler != rl_signal_handler || old_handler.sa_handler != rl_signal_handler)
      memcpy (ohandler, &old_handler, sizeof (sighandler_cxt));
  
    return (ohandler->sa_handler);
  }
  
  static void
  rl_maybe_set_sighandler (sig, handler, ohandler)
       int sig;
       SigHandler *handler;
       sighandler_cxt *ohandler;
  {
    sighandler_cxt dummy;
    SigHandler *oh;
  
    sigemptyset (&dummy.sa_mask);
    oh = rl_set_sighandler (sig, handler, ohandler);
    if (oh == (SigHandler *)SIG_IGN)
      rl_sigaction (sig, ohandler, &dummy);
  }
  
  int
  rl_set_signals ()
  {
    sighandler_cxt dummy;
    SigHandler *oh;
  #if defined (HAVE_POSIX_SIGNALS)
    static int sigmask_set = 0;
    static sigset_t bset, oset;
  #endif
  
  #if defined (HAVE_POSIX_SIGNALS)
    if (rl_catch_signals && sigmask_set == 0)
      {
        sigemptyset (&bset);
  
        sigaddset (&bset, SIGINT);
        sigaddset (&bset, SIGINT);
  #if defined (SIGQUIT)
        sigaddset (&bset, SIGQUIT);
  #endif
  #if defined (SIGALRM)
        sigaddset (&bset, SIGALRM);
  #endif
  #if defined (SIGTSTP)
        sigaddset (&bset, SIGTSTP);
  #endif
  #if defined (SIGTTIN)
        sigaddset (&bset, SIGTTIN);
  #endif
  #if defined (SIGTTOU)
        sigaddset (&bset, SIGTTOU);
  #endif
        sigmask_set = 1;
      }      
  #endif /* HAVE_POSIX_SIGNALS */
  
    if (rl_catch_signals && signals_set_flag == 0)
      {
  #if defined (HAVE_POSIX_SIGNALS)
        sigemptyset (&oset);
        sigprocmask (SIG_BLOCK, &bset, &oset);
  #endif
  
        rl_maybe_set_sighandler (SIGINT, rl_signal_handler, &old_int);
        rl_maybe_set_sighandler (SIGTERM, rl_signal_handler, &old_term);
  #if defined (SIGQUIT)
        rl_maybe_set_sighandler (SIGQUIT, rl_signal_handler, &old_quit);
  #endif
  
  #if defined (SIGALRM)
        oh = rl_set_sighandler (SIGALRM, rl_signal_handler, &old_alrm);
        if (oh == (SigHandler *)SIG_IGN)
  	rl_sigaction (SIGALRM, &old_alrm, &dummy);
  #if defined (HAVE_POSIX_SIGNALS) && defined (SA_RESTART)
        /* If the application using readline has already installed a signal
  	 handler with SA_RESTART, SIGALRM will cause reads to be restarted
  	 automatically, so readline should just get out of the way.  Since
  	 we tested for SIG_IGN above, we can just test for SIG_DFL here. */
        if (oh != (SigHandler *)SIG_DFL && (old_alrm.sa_flags & SA_RESTART))
  	rl_sigaction (SIGALRM, &old_alrm, &dummy);
  #endif /* HAVE_POSIX_SIGNALS */
  #endif /* SIGALRM */
  
  #if defined (SIGTSTP)
        rl_maybe_set_sighandler (SIGTSTP, rl_signal_handler, &old_tstp);
  #endif /* SIGTSTP */
  
  #if defined (SIGTTOU)
        rl_maybe_set_sighandler (SIGTTOU, rl_signal_handler, &old_ttou);
  #endif /* SIGTTOU */
  
  #if defined (SIGTTIN)
        rl_maybe_set_sighandler (SIGTTIN, rl_signal_handler, &old_ttin);
  #endif /* SIGTTIN */
  
        signals_set_flag = 1;
  
  #if defined (HAVE_POSIX_SIGNALS)
        sigprocmask (SIG_SETMASK, &oset, (sigset_t *)NULL);
  #endif
      }
  
  #if defined (SIGWINCH)
    if (rl_catch_sigwinch && sigwinch_set_flag == 0)
      {
        rl_maybe_set_sighandler (SIGWINCH, rl_sigwinch_handler, &old_winch);
        sigwinch_set_flag = 1;
      }
  #endif /* SIGWINCH */
  
    return 0;
  }
  
  int
  rl_clear_signals ()
  {
    sighandler_cxt dummy;
  
    if (rl_catch_signals && signals_set_flag == 1)
      {
        sigemptyset (&dummy.sa_mask);
  
        rl_sigaction (SIGINT, &old_int, &dummy);
        rl_sigaction (SIGTERM, &old_term, &dummy);
  #if defined (SIGQUIT)
        rl_sigaction (SIGQUIT, &old_quit, &dummy);
  #endif
  #if defined (SIGALRM)
        rl_sigaction (SIGALRM, &old_alrm, &dummy);
  #endif
  
  #if defined (SIGTSTP)
        rl_sigaction (SIGTSTP, &old_tstp, &dummy);
  #endif /* SIGTSTP */
  
  #if defined (SIGTTOU)
        rl_sigaction (SIGTTOU, &old_ttou, &dummy);
  #endif /* SIGTTOU */
  
  #if defined (SIGTTIN)
        rl_sigaction (SIGTTIN, &old_ttin, &dummy);
  #endif /* SIGTTIN */
  
        signals_set_flag = 0;
      }
  
  #if defined (SIGWINCH)
    if (rl_catch_sigwinch && sigwinch_set_flag == 1)
      {
        sigemptyset (&dummy.sa_mask);
        rl_sigaction (SIGWINCH, &old_winch, &dummy);
        sigwinch_set_flag = 0;
      }
  #endif
  
    return 0;
  }
  
  /* Clean up the terminal and readline state after catching a signal, before
     resending it to the calling application. */
  void
  rl_cleanup_after_signal ()
  {
    _rl_clean_up_for_exit ();
    if (rl_deprep_term_function)
      (*rl_deprep_term_function) ();
    rl_clear_pending_input ();
    rl_clear_signals ();
  }
  
  /* Reset the terminal and readline state after a signal handler returns. */
  void
  rl_reset_after_signal ()
  {
    if (rl_prep_term_function)
      (*rl_prep_term_function) (_rl_meta_flag);
    rl_set_signals ();
  }
  
  /* Free up the readline variable line state for the current line (undo list,
     any partial history entry, any keyboard macros in progress, and any
     numeric arguments in process) after catching a signal, before calling
     rl_cleanup_after_signal(). */ 
  void
  rl_free_line_state ()
  {
    register HIST_ENTRY *entry;
  
    rl_free_undo_list ();
  
    entry = current_history ();
    if (entry)
      entry->data = (char *)NULL;
  
    _rl_kill_kbd_macro ();
    rl_clear_message ();
    _rl_reset_argument ();
  }
  
  #endif  /* HANDLE_SIGNALS */
  