text: /*-
   * Copyright (c) 1991, 1993
   *	The Regents of the University of California.  All rights reserved.
   * Copyright (c) 1997-2005
   *	Herbert Xu <herbert@gondor.apana.org.au>.  All rights reserved.
   *
   * This code is derived from software contributed to Berkeley by
   * Kenneth Almquist.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include <signal.h>
  #include <unistd.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include "shell.h"
  #include "main.h"
  #include "nodes.h"	/* for other headers */
  #include "eval.h"
  #include "init.h"
  #include "jobs.h"
  #include "show.h"
  #include "options.h"
  #include "syntax.h"
  #include "output.h"
  #include "memalloc.h"
  #include "error.h"
  #include "trap.h"
  #include "mystring.h"
  
  /*
   * Sigmode records the current value of the signal handlers for the various
   * modes.  A value of zero means that the current handler is not known.
   * S_HARD_IGN indicates that the signal was ignored on entry to the shell,
   */
  
  #define S_DFL 1			/* default signal handling (SIG_DFL) */
  #define S_CATCH 2		/* signal is caught */
  #define S_IGN 3			/* signal is ignored (SIG_IGN) */
  #define S_HARD_IGN 4		/* signal is ignored permenantly */
  #define S_RESET 5		/* temporary - to reset a hard ignored sig */
  
  
  /* trap handler commands */
  MKINIT char *trap[NSIG];
  /* number of non-null traps */
  int trapcnt;
  /* current value of signal */
  char sigmode[NSIG - 1];
  /* indicates specified signal received */
  static char gotsig[NSIG - 1];
  /* last pending signal */
  volatile sig_atomic_t pending_sig;
  /* received SIGCHLD */
  volatile sig_atomic_t gotsigchld;
  
  extern char *signal_names[];
  
  static int decode_signum(const char *);
  
  #ifdef mkinit
  INCLUDE "memalloc.h"
  INCLUDE "trap.h"
  
  INIT {
  	sigmode[SIGCHLD - 1] = S_DFL;
  	setsignal(SIGCHLD);
  }
  
  FORKRESET {
  	char **tp;
  
  	INTOFF;
  	for (tp = trap ; tp < &trap[NSIG] ; tp++) {
  		if (*tp && **tp) {	/* trap not NULL or SIG_IGN */
  			ckfree(*tp);
  			*tp = NULL;
  			if (tp != &trap[0])
  				setsignal(tp - trap);
  		}
  	}
  	trapcnt = 0;
  	INTON;
  }
  #endif
  
  /*
   * The trap builtin.
   */
  
  int
  trapcmd(int argc, char **argv)
  {
  	char *action;
  	char **ap;
  	int signo;
  
  	nextopt(nullstr);
  	ap = argptr;
  	if (!*ap) {
  		for (signo = 0 ; signo < NSIG ; signo++) {
  			if (trap[signo] != NULL) {
  				out1fmt(
  					"trap -- %s %s\n",
  					single_quote(trap[signo]),
  					signal_names[signo]
  				);
  			}
  		}
  		return 0;
  	}
  	if (!ap[1] || decode_signum(*ap) >= 0)
  		action = NULL;
  	else
  		action = *ap++;
  	while (*ap) {
  		if ((signo = decode_signal(*ap, 0)) < 0) {
  			outfmt(out2, "trap: %s: bad trap\n", *ap);
  			return 1;
  		}
  		INTOFF;
  		if (action) {
  			if (action[0] == '-' && action[1] == '\0')
  				action = NULL;
  			else {
  				if (*action)
  					trapcnt++;
  				action = savestr(action);
  			}
  		}
  		if (trap[signo]) {
  			if (*trap[signo])
  				trapcnt--;
  			ckfree(trap[signo]);
  		}
  		trap[signo] = action;
  		if (signo != 0)
  			setsignal(signo);
  		INTON;
  		ap++;
  	}
  	return 0;
  }
  
  
  
  /*
   * Set the signal handler for the specified signal.  The routine figures
   * out what it should be set to.
   */
  
  void
  setsignal(int signo)
  {
  	int action;
  	int lvforked;
  	char *t, tsig;
  	struct sigaction act;
  
  	lvforked = vforked;
  
  	if ((t = trap[signo]) == NULL)
  		action = S_DFL;
  	else if (*t != '\0')
  		action = S_CATCH;
  	else
  		action = S_IGN;
  	if (rootshell && action == S_DFL && !lvforked) {
  		switch (signo) {
  		case SIGINT:
  			if (iflag || minusc || sflag == 0)
  				action = S_CATCH;
  			break;
  		case SIGQUIT:
  #ifdef DEBUG
  			if (debug)
  				break;
  #endif
  			/* FALLTHROUGH */
  		case SIGTERM:
  			if (iflag)
  				action = S_IGN;
  			break;
  #if JOBS
  		case SIGTSTP:
  		case SIGTTOU:
  			if (mflag)
  				action = S_IGN;
  			break;
  #endif
  		}
  	}
  
  	if (signo == SIGCHLD)
  		action = S_CATCH;
  
  	t = &sigmode[signo - 1];
  	tsig = *t;
  	if (tsig == 0) {
  		/*
  		 * current setting unknown
  		 */
  		if (sigaction(signo, 0, &act) == -1) {
  			/*
  			 * Pretend it worked; maybe we should give a warning
  			 * here, but other shells don't. We don't alter
  			 * sigmode, so that we retry every time.
  			 */
  			return;
  		}
  		if (act.sa_handler == SIG_IGN) {
  			if (mflag && (signo == SIGTSTP ||
  			     signo == SIGTTIN || signo == SIGTTOU)) {
  				tsig = S_IGN;	/* don't hard ignore these */
  			} else
  				tsig = S_HARD_IGN;
  		} else {
  			tsig = S_RESET;	/* force to be set */
  		}
  	}
  	if (tsig == S_HARD_IGN || tsig == action)
  		return;
  	switch (action) {
  	case S_CATCH:
  		act.sa_handler = onsig;
  		break;
  	case S_IGN:
  		act.sa_handler = SIG_IGN;
  		break;
  	default:
  		act.sa_handler = SIG_DFL;
  	}
  	if (!lvforked)
  		*t = action;
  	act.sa_flags = 0;
  	sigfillset(&act.sa_mask);
  	sigaction(signo, &act, 0);
  }
  
  /*
   * Ignore a signal.
   */
  
  void
  ignoresig(int signo)
  {
  	if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
  		signal(signo, SIG_IGN);
  	}
  	if (!vforked)
  		sigmode[signo - 1] = S_HARD_IGN;
  }
  
  
  
  /*
   * Signal handler.
   */
  
  void
  onsig(int signo)
  {
  	if (vforked)
  		return;
  
  	if (signo == SIGCHLD) {
  		gotsigchld = 1;
  		if (!trap[SIGCHLD])
  			return;
  	}
  
  	gotsig[signo - 1] = 1;
  	pending_sig = signo;
  
  	if (signo == SIGINT && !trap[SIGINT]) {
  		if (!suppressint)
  			onint();
  		intpending = 1;
  	}
  }
  
  
  
  /*
   * Called to execute a trap.  Perhaps we should avoid entering new trap
   * handlers while we are executing a trap handler.
   */
  
  void dotrap(void)
  {
  	char *p;
  	char *q;
  	int i;
  	int status, last_status;
  
  	if (!pending_sig)
  		return;
  
  	status = savestatus;
  	last_status = status;
  	if (likely(status < 0)) {
  		status = exitstatus;
  		savestatus = status;
  	}
  	pending_sig = 0;
  	barrier();
  
  	for (i = 0, q = gotsig; i < NSIG - 1; i++, q++) {
  		if (!*q)
  			continue;
  
  		if (evalskip) {
  			pending_sig = i + 1;
  			break;
  		}
  
  		*q = 0;
  
  		p = trap[i + 1];
  		if (!p)
  			continue;
  		evalstring(p, 0);
  		if (evalskip != SKIPFUNC)
  			exitstatus = status;
  	}
  
  	savestatus = last_status;
  }
  
  
  
  /*
   * Controls whether the shell is interactive or not.
   */
  
  
  void
  setinteractive(int on)
  {
  	static int is_interactive;
  
  	if (++on == is_interactive)
  		return;
  	is_interactive = on;
  	setsignal(SIGINT);
  	setsignal(SIGQUIT);
  	setsignal(SIGTERM);
  }
  
  
  
  /*
   * Called to exit the shell.
   */
  
  void
  exitshell(void)
  {
  	struct jmploc loc;
  	char *p;
  
  	savestatus = exitstatus;
  	TRACE(("pid %d, exitshell(%d)\n", getpid(), savestatus));
  	if (setjmp(loc.loc))
  		goto out;
  	handler = &loc;
  	if ((p = trap[0])) {
  		trap[0] = NULL;
  		evalskip = 0;
  		evalstring(p, 0);
  		evalskip = SKIPFUNCDEF;
  	}
  out:
  	exitreset();
  	/*
  	 * Disable job control so that whoever had the foreground before we
  	 * started can get it back.
  	 */
  	if (likely(!setjmp(loc.loc)))
  		setjobctl(0);
  	flushall();
  	_exit(exitstatus);
  	/* NOTREACHED */
  }
  
  static int decode_signum(const char *string)
  {
  	int signo = -1;
  
  	if (is_number(string)) {
  		signo = atoi(string);
  		if (signo >= NSIG)
  			signo = -1;
  	}
  
  	return signo;
  }
  
  int decode_signal(const char *string, int minsig)
  {
  	int signo;
  
  	signo = decode_signum(string);
  	if (signo >= 0)
  		return signo;
  
  	for (signo = minsig; signo < NSIG; signo++) {
  		if (!strcasecmp(string, signal_names[signo])) {
  			return signo;
  		}
  	}
  
  	return -1;
  }
  
  void sigblockall(sigset_t *oldmask)
  {
  	sigset_t mask;
  
  	sigfillset(&mask);
  	sigprocmask(SIG_SETMASK, &mask, oldmask);
  }
  