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464 lines
9.5 KiB
C
464 lines
9.5 KiB
C
/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Kenneth Almquist.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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#if 0
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static char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95";
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#endif
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static const char rcsid[] =
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"$Id: trap.c,v 1.18 1999/04/01 13:27:36 cracauer Exp $";
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#endif /* not lint */
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#include <signal.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include "shell.h"
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#include "main.h"
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#include "nodes.h" /* for other headers */
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#include "eval.h"
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#include "jobs.h"
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#include "show.h"
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#include "options.h"
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#include "syntax.h"
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#include "output.h"
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#include "memalloc.h"
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#include "error.h"
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#include "trap.h"
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#include "mystring.h"
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/*
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* Sigmode records the current value of the signal handlers for the various
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* modes. A value of zero means that the current handler is not known.
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* S_HARD_IGN indicates that the signal was ignored on entry to the shell,
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*/
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#define S_DFL 1 /* default signal handling (SIG_DFL) */
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#define S_CATCH 2 /* signal is caught */
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#define S_IGN 3 /* signal is ignored (SIG_IGN) */
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#define S_HARD_IGN 4 /* signal is ignored permanently */
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#define S_RESET 5 /* temporary - to reset a hard ignored sig */
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MKINIT char sigmode[NSIG]; /* current value of signal */
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int pendingsigs; /* indicates some signal received */
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int in_dotrap; /* do we execute in a trap handler? */
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static char *volatile trap[NSIG]; /* trap handler commands */
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static volatile sig_atomic_t gotsig[NSIG];
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/* indicates specified signal received */
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static int ignore_sigchld; /* Used while handling SIGCHLD traps. */
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static int getsigaction __P((int, sig_t *));
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/*
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* Map a string to a signal number.
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*/
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static int
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sigstring_to_signum(sig)
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char *sig;
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{
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if (is_number(sig)) {
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int signo;
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signo = atoi(sig);
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return ((signo >= 0 && signo < NSIG) ? signo : (-1));
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} else if (strcasecmp(sig, "exit") == 0) {
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return (0);
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} else {
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int n;
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if (strncasecmp(sig, "sig", 3) == 0)
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sig += 3;
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for (n = 1; n < NSIG; n++)
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if (strcasecmp(sys_signame[n], sig) == 0)
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return (n);
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}
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return (-1);
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}
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/*
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* Print a list of valid signal names.
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*/
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static void
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printsignals()
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{
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int n;
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for (n = 1; n < NSIG; n++) {
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out1fmt("%s", sys_signame[n]);
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if (n == (NSIG / 2) || n == (NSIG - 1))
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out1str("\n");
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else
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out1c(' ');
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}
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}
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/*
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* The trap builtin.
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*/
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int
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trapcmd(argc, argv)
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int argc;
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char **argv;
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{
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char *action;
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int signo;
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if (argc <= 1) {
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for (signo = 0 ; signo < NSIG ; signo++) {
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if (trap[signo] != NULL)
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out1fmt("trap -- '%s' %s\n", trap[signo],
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(signo) ? sys_signame[signo] : "exit");
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}
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return 0;
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}
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action = NULL;
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if (*++argv && strcmp(*argv, "--") == 0)
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argv++;
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if (*argv && sigstring_to_signum(*argv) == -1) {
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if ((*argv)[0] != '-') {
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action = *argv;
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argv++;
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} else if ((*argv)[1] == '\0') {
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argv++;
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} else if ((*argv)[1] == 'l' && (*argv)[2] == '\0') {
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printsignals();
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return 0;
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} else {
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error("bad option %s", *argv);
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}
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}
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while (*argv) {
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if ((signo = sigstring_to_signum(*argv)) == -1)
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error("bad signal %s", *argv);
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INTOFF;
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if (action)
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action = savestr(action);
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if (trap[signo])
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ckfree(trap[signo]);
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trap[signo] = action;
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if (signo != 0)
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setsignal(signo);
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INTON;
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argv++;
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}
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return 0;
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}
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/*
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* Clear traps on a fork.
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*/
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void
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clear_traps()
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{
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char *volatile *tp;
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for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) {
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if (*tp && **tp) { /* trap not NULL or SIG_IGN */
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INTOFF;
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ckfree(*tp);
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*tp = NULL;
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if (tp != &trap[0])
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setsignal(tp - trap);
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INTON;
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}
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}
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}
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/*
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* Set the signal handler for the specified signal. The routine figures
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* out what it should be set to.
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*/
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void
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setsignal(signo)
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int signo;
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{
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int action;
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sig_t sig, sigact = SIG_DFL;
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char *t;
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if ((t = trap[signo]) == NULL)
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action = S_DFL;
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else if (*t != '\0')
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action = S_CATCH;
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else
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action = S_IGN;
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if (action == S_DFL) {
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switch (signo) {
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case SIGINT:
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action = S_CATCH;
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break;
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case SIGQUIT:
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#ifdef DEBUG
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{
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extern int debug;
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if (debug)
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break;
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}
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#endif
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action = S_CATCH;
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break;
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case SIGTERM:
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if (rootshell && iflag)
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action = S_IGN;
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break;
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#if JOBS
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case SIGTSTP:
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case SIGTTOU:
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if (rootshell && mflag)
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action = S_IGN;
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break;
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#endif
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}
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}
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t = &sigmode[signo];
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if (*t == 0) {
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/*
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* current setting unknown
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*/
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if (!getsigaction(signo, &sigact)) {
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/*
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* Pretend it worked; maybe we should give a warning
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* here, but other shells don't. We don't alter
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* sigmode, so that we retry every time.
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*/
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return;
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}
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if (sigact == SIG_IGN) {
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if (mflag && (signo == SIGTSTP ||
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signo == SIGTTIN || signo == SIGTTOU)) {
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*t = S_IGN; /* don't hard ignore these */
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} else
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*t = S_HARD_IGN;
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} else {
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*t = S_RESET; /* force to be set */
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}
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}
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if (*t == S_HARD_IGN || *t == action)
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return;
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switch (action) {
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case S_DFL: sigact = SIG_DFL; break;
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case S_CATCH: sigact = onsig; break;
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case S_IGN: sigact = SIG_IGN; break;
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}
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*t = action;
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sig = signal(signo, sigact);
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#ifdef BSD
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if (sig != SIG_ERR && action == S_CATCH)
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siginterrupt(signo, 1);
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#endif
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}
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/*
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* Return the current setting for sig w/o changing it.
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*/
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static int
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getsigaction(signo, sigact)
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int signo;
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sig_t *sigact;
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{
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struct sigaction sa;
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if (sigaction(signo, (struct sigaction *)0, &sa) == -1)
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return 0;
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*sigact = (sig_t) sa.sa_handler;
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return 1;
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}
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/*
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* Ignore a signal.
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*/
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void
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ignoresig(signo)
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int signo;
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{
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if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) {
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signal(signo, SIG_IGN);
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}
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sigmode[signo] = S_HARD_IGN;
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}
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#ifdef mkinit
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INCLUDE <signal.h>
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INCLUDE "trap.h"
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SHELLPROC {
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char *sm;
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clear_traps();
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for (sm = sigmode ; sm < sigmode + NSIG ; sm++) {
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if (*sm == S_IGN)
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*sm = S_HARD_IGN;
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}
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}
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#endif
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/*
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* Signal handler.
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*/
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void
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onsig(signo)
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int signo;
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{
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#ifndef BSD
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signal(signo, onsig);
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#endif
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if (signo == SIGINT && trap[SIGINT] == NULL) {
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onint();
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return;
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}
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if (signo != SIGCHLD || !ignore_sigchld)
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gotsig[signo] = 1;
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pendingsigs++;
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/* If we are currently in a wait builtin, prepare to break it */
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if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0)
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breakwaitcmd = 1;
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/*
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* If a trap is set, not ignored and not the null command, we need
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* to make sure traps are executed even when a child blocks signals.
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*/
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if (Tflag &&
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trap[signo] != NULL &&
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! trap[signo][0] == '\0' &&
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! (trap[signo][0] == ':' && trap[signo][1] == '\0'))
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breakwaitcmd = 1;
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}
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/*
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* Called to execute a trap. Perhaps we should avoid entering new trap
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* handlers while we are executing a trap handler.
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*/
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void
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dotrap()
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{
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int i;
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int savestatus;
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in_dotrap++;
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for (;;) {
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for (i = 1; i < NSIG; i++) {
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if (gotsig[i]) {
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gotsig[i] = 0;
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if (trap[i]) {
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/*
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* Ignore SIGCHLD to avoid infinite recursion
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* if the trap action does a fork.
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*/
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if (i == SIGCHLD)
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ignore_sigchld++;
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savestatus = exitstatus;
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evalstring(trap[i]);
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exitstatus = savestatus;
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if (i == SIGCHLD)
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ignore_sigchld--;
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}
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break;
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}
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}
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if (i >= NSIG)
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break;
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}
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in_dotrap--;
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pendingsigs = 0;
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}
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/*
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* Controls whether the shell is interactive or not.
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*/
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void
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setinteractive(on)
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int on;
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{
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static int is_interactive = -1;
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if (on == is_interactive)
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return;
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setsignal(SIGINT);
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setsignal(SIGQUIT);
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setsignal(SIGTERM);
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is_interactive = on;
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}
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/*
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* Called to exit the shell.
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*/
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void
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exitshell(status)
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int status;
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{
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struct jmploc loc1, loc2;
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char *p;
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TRACE(("exitshell(%d) pid=%d\n", status, getpid()));
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if (setjmp(loc1.loc)) {
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goto l1;
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}
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if (setjmp(loc2.loc)) {
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goto l2;
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}
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handler = &loc1;
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if ((p = trap[0]) != NULL && *p != '\0') {
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trap[0] = NULL;
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evalstring(p);
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}
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l1: handler = &loc2; /* probably unnecessary */
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flushall();
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#if JOBS
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setjobctl(0);
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#endif
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l2: _exit(status);
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}
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