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f98e1b8071
while remaining (becoming :) compatible with other popular shells. Specifically these changes include: 1) Implement 'trap -l' to get a list of valid signals names. This is useful if you wanted to do something like reset all signal handlers to there defaults values, in which case something like this will do the trick. trap `trap -l` 2) Reformat the output of 'trap' so it can be saved and later eval'd to restore the saved settings. 3) Allow the use of signal names as well as signal numbers. 4) Fix trap handling of SIGCHLD so that commands like the following (albeit, contrived) won't cause sh(1) to recurse ad infinitum. trap uname 0 20 5) Make variables static that are used only in trap.c. 6) Minor 'style(9) police' mods.
438 lines
8.7 KiB
C
438 lines
8.7 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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* $Id: trap.c,v 1.5 1996/12/14 06:19:32 steve Exp $
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*/
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#ifndef lint
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static char const sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95";
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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 permenantly */
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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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static char *trap[NSIG]; /* trap handler commands */
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static char gotsig[NSIG]; /* 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 **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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long
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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 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 (rootshell && action == S_DFL) {
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switch (signo) {
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case SIGINT:
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if (iflag)
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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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/* FALLTHROUGH */
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case SIGTERM:
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if (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 (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 0;
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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 0;
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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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return (long)signal(signo, sigact);
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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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signal(signo, onsig);
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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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}
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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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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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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 = 0;
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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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