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mirror of https://git.FreeBSD.org/src.git synced 2024-12-23 11:18:54 +00:00
freebsd/bin/sh/trap.c
Martin Cracauer 7a8e920bb9 Do not exit on SIGINT in non-interactive shells, fixes PR 1206,
i.e. this makes emacs usable from system(3). Programs called from
shellscripts are now required to exit with proper signal status. That
means, they have to kill themself. Exiting with faked numerical exit
code is not sufficient.

Exit with proper signal status if script exits on signal.

Make the wait builtin interruptable, both with and without traps set.

Use volatile sig_atomic_t where (and only where) appropriate.

(Almost) fix printing of newlines on SIGINT.

Make traps setable from trap handlers. This is needed for shellscripts
that catch SIGINT for cleanup work but intend to exit on it, hance
have to kill themself from a trap handler. I.e. mkdep.

While I'm at it, make it -Wall clean. -Wall is not enabled in
Makefile, since vararg warnx() macro calls in usr.bin/printf/printf.c
are not -Wall-able.
PR:		1206
Obtained from:	Basic SIGINT fix from Bruce Evans
1998-08-24 10:20:37 +00:00

454 lines
9.1 KiB
C

/*-
* Copyright (c) 1991, 1993
* The Regents of the University of California. 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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.
*/
#ifndef lint
#if 0
static char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95";
#endif
static const char rcsid[] =
"$Id: trap.c,v 1.11 1998/05/18 06:44:22 charnier Exp $";
#endif /* not lint */
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include "shell.h"
#include "main.h"
#include "nodes.h" /* for other headers */
#include "eval.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 */
MKINIT char sigmode[NSIG]; /* current value of signal */
int pendingsigs; /* indicates some signal received */
int in_dotrap = 0; /* Do we execute in a trap handler? */
static char *trap[NSIG]; /* trap handler commands */
static volatile sig_atomic_t gotsig[NSIG];
/* indicates specified signal received */
static int ignore_sigchld; /* Used while handling SIGCHLD traps. */
static int getsigaction __P((int, sig_t *));
/*
* Map a string to a signal number.
*/
static int
sigstring_to_signum(sig)
char *sig;
{
if (is_number(sig)) {
int signo;
signo = atoi(sig);
return ((signo >= 0 && signo < NSIG) ? signo : (-1));
} else if (strcasecmp(sig, "exit") == 0) {
return (0);
} else {
int n;
if (strncasecmp(sig, "sig", 3) == 0)
sig += 3;
for (n = 1; n < NSIG; n++)
if (strcasecmp(sys_signame[n], sig) == 0)
return (n);
}
return (-1);
}
/*
* Print a list of valid signal names.
*/
static void
printsignals()
{
int n;
for (n = 1; n < NSIG; n++) {
out1fmt("%s", sys_signame[n]);
if (n == (NSIG / 2) || n == (NSIG - 1))
out1str("\n");
else
out1c(' ');
}
}
/*
* The trap builtin.
*/
int
trapcmd(argc, argv)
int argc;
char **argv;
{
char *action;
int signo;
if (argc <= 1) {
for (signo = 0 ; signo < NSIG ; signo++) {
if (trap[signo] != NULL)
out1fmt("trap -- '%s' %s\n", trap[signo],
(signo) ? sys_signame[signo] : "exit");
}
return 0;
}
action = NULL;
if (*++argv && strcmp(*argv, "--") == 0)
argv++;
if (*argv && sigstring_to_signum(*argv) == -1) {
if ((*argv)[0] != '-') {
action = *argv;
argv++;
} else if ((*argv)[1] == '\0') {
argv++;
} else if ((*argv)[1] == 'l' && (*argv)[2] == '\0') {
printsignals();
return 0;
} else {
error("bad option %s", *argv);
}
}
while (*argv) {
if ((signo = sigstring_to_signum(*argv)) == -1)
error("bad signal %s", *argv);
INTOFF;
if (action)
action = savestr(action);
if (trap[signo])
ckfree(trap[signo]);
trap[signo] = action;
if (signo != 0)
setsignal(signo);
INTON;
argv++;
}
return 0;
}
/*
* Clear traps on a fork.
*/
void
clear_traps()
{
char **tp;
for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) {
if (*tp && **tp) { /* trap not NULL or SIG_IGN */
INTOFF;
ckfree(*tp);
*tp = NULL;
if (tp != &trap[0])
setsignal(tp - trap);
INTON;
}
}
}
/*
* Set the signal handler for the specified signal. The routine figures
* out what it should be set to.
*/
void
setsignal(signo)
int signo;
{
int action;
sig_t sig, sigact = SIG_DFL;
char *t;
if ((t = trap[signo]) == NULL)
action = S_DFL;
else if (*t != '\0')
action = S_CATCH;
else
action = S_IGN;
if (action == S_DFL) {
switch (signo) {
case SIGINT:
action = S_CATCH;
break;
case SIGQUIT:
#ifdef DEBUG
{
extern int debug;
if (debug)
break;
}
#endif
action = S_IGN;
break;
case SIGTERM:
if (rootshell && iflag)
action = S_IGN;
break;
#if JOBS
case SIGTSTP:
case SIGTTOU:
if (rootshell && mflag)
action = S_IGN;
break;
#endif
}
}
t = &sigmode[signo];
if (*t == 0) {
/*
* current setting unknown
*/
if (!getsigaction(signo, &sigact)) {
/*
* 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 (sigact == SIG_IGN) {
if (mflag && (signo == SIGTSTP ||
signo == SIGTTIN || signo == SIGTTOU)) {
*t = S_IGN; /* don't hard ignore these */
} else
*t = S_HARD_IGN;
} else {
*t = S_RESET; /* force to be set */
}
}
if (*t == S_HARD_IGN || *t == action)
return;
switch (action) {
case S_DFL: sigact = SIG_DFL; break;
case S_CATCH: sigact = onsig; break;
case S_IGN: sigact = SIG_IGN; break;
}
*t = action;
sig = signal(signo, sigact);
#ifdef BSD
if (sig != SIG_ERR && action == S_CATCH)
siginterrupt(signo, 1);
#endif
}
/*
* Return the current setting for sig w/o changing it.
*/
static int
getsigaction(signo, sigact)
int signo;
sig_t *sigact;
{
struct sigaction sa;
if (sigaction(signo, (struct sigaction *)0, &sa) == -1)
return 0;
*sigact = (sig_t) sa.sa_handler;
return 1;
}
/*
* Ignore a signal.
*/
void
ignoresig(signo)
int signo;
{
if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) {
signal(signo, SIG_IGN);
}
sigmode[signo] = S_HARD_IGN;
}
#ifdef mkinit
INCLUDE <signal.h>
INCLUDE "trap.h"
SHELLPROC {
char *sm;
clear_traps();
for (sm = sigmode ; sm < sigmode + NSIG ; sm++) {
if (*sm == S_IGN)
*sm = S_HARD_IGN;
}
}
#endif
/*
* Signal handler.
*/
void
onsig(signo)
int signo;
{
#ifndef BSD
signal(signo, onsig);
#endif
if (signo == SIGINT && trap[SIGINT] == NULL) {
onint();
return;
}
if (signo != SIGCHLD || !ignore_sigchld)
gotsig[signo] = 1;
pendingsigs++;
if (signo == SIGINT && in_waitcmd != 0) {
dotrap();
breakwaitcmd = 1;
}
}
/*
* Called to execute a trap. Perhaps we should avoid entering new trap
* handlers while we are executing a trap handler.
*/
void
dotrap()
{
int i;
int savestatus;
in_dotrap++;
for (;;) {
for (i = 1; i < NSIG; i++) {
if (gotsig[i]) {
gotsig[i] = 0;
if (trap[i]) {
/*
* Ignore SIGCHLD to avoid infinite recursion
* if the trap action does a fork.
*/
if (i == SIGCHLD)
ignore_sigchld++;
savestatus = exitstatus;
evalstring(trap[i]);
exitstatus = savestatus;
if (i == SIGCHLD)
ignore_sigchld--;
}
break;
}
}
if (i >= NSIG)
break;
}
in_dotrap--;
pendingsigs = 0;
}
/*
* Controls whether the shell is interactive or not.
*/
void
setinteractive(on)
int on;
{
static int is_interactive = -1;
if (on == is_interactive)
return;
setsignal(SIGINT);
setsignal(SIGQUIT);
setsignal(SIGTERM);
is_interactive = on;
}
/*
* Called to exit the shell.
*/
void
exitshell(status)
int status;
{
struct jmploc loc1, loc2;
char *p;
TRACE(("exitshell(%d) pid=%d\n", status, getpid()));
if (setjmp(loc1.loc)) {
goto l1;
}
if (setjmp(loc2.loc)) {
goto l2;
}
handler = &loc1;
if ((p = trap[0]) != NULL && *p != '\0') {
trap[0] = NULL;
evalstring(p);
}
l1: handler = &loc2; /* probably unnecessary */
flushall();
#if JOBS
setjobctl(0);
#endif
l2: _exit(status);
}