e1849b79b1
The problem was that system calls got restarted after a signal, instead of returning EINTR. Thus the read builtin, had no way to know that a signal occured that could change the course of execution. Since the code has sprinkled checks for EINTR all over the place, it is supposed to work properly with non restartable syscalls. The fix is to use siginterrupt(signo, 1), before setting a signal handler, to make sure that system calls don't get restarted.
386 lines
7.6 KiB
C
386 lines
7.6 KiB
C
/* $NetBSD: trap.c,v 1.19 1999/01/18 16:18:04 christos Exp $ */
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/*-
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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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#include <sys/cdefs.h>
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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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#else
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__RCSID("$NetBSD: trap.c,v 1.19 1999/01/18 16:18:04 christos Exp $");
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#endif
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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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extern char nullstr[1]; /* null string */
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char *trap[NSIG+1]; /* trap handler commands */
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MKINIT char sigmode[NSIG]; /* current value of signal */
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char gotsig[NSIG]; /* indicates specified signal received */
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int pendingsigs; /* indicates some signal received */
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static int getsigaction __P((int, sig_t *));
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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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char **ap;
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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("%d: %s\n", signo, trap[signo]);
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}
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return 0;
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}
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ap = argv + 1;
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if (is_number(*ap))
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action = NULL;
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else
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action = *ap++;
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while (*ap) {
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if ((signo = number(*ap)) < 0 || signo > NSIG)
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error("%s: bad trap", *ap);
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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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ap++;
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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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char **tp;
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for (tp = trap ; tp <= &trap[NSIG] ; 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 - 1];
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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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siginterrupt(signo, 1);
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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 - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
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signal(signo, SIG_IGN);
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}
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sigmode[signo - 1] = 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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gotsig[signo - 1] = 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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int i;
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int savestatus;
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for (;;) {
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for (i = 1 ; ; i++) {
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if (gotsig[i - 1])
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break;
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if (i >= NSIG)
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goto done;
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}
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gotsig[i - 1] = 0;
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savestatus=exitstatus;
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evalstring(trap[i]);
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exitstatus=savestatus;
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}
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done:
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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;
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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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/* NOTREACHED */
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}
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