NetBSD/bin/sh/trap.c

475 lines
9.4 KiB
C

/* $NetBSD: trap.c,v 1.33 2005/07/15 17:23:48 christos Exp $ */
/*-
* 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. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95";
#else
__RCSID("$NetBSD: trap.c,v 1.33 2005/07/15 17:23:48 christos Exp $");
#endif
#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"
#include "var.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 */
char *trap[NSIG+1]; /* trap handler commands */
MKINIT char sigmode[NSIG]; /* current value of signal */
char gotsig[NSIG]; /* indicates specified signal received */
int pendingsigs; /* indicates some signal received */
static int getsigaction(int, sig_t *);
/*
* return the signal number described by `p' (as a number or a name)
* or -1 if it isn't one
*/
static int
signame_to_signum(const char *p)
{
int i;
if (is_number(p))
return number(p);
if (strcasecmp(p, "exit") == 0 )
return 0;
if (strncasecmp(p, "sig", 3) == 0)
p += 3;
for (i = 0; i < NSIG; ++i)
if (strcasecmp (p, sys_signame[i]) == 0)
return i;
return -1;
}
/*
* Print a list of valid signal names
*/
static void
printsignals(void)
{
int n;
out1str("EXIT ");
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(int argc, char **argv)
{
char *action;
char **ap;
int signo;
if (argc <= 1) {
for (signo = 0 ; signo <= NSIG ; signo++)
if (trap[signo] != NULL) {
out1fmt("trap -- ");
print_quoted(trap[signo]);
out1fmt(" %s\n",
(signo) ? sys_signame[signo] : "EXIT");
}
return 0;
}
ap = argv + 1;
action = NULL;
if (strcmp(*ap, "--") == 0)
if (*++ap == NULL)
return 0;
if (signame_to_signum(*ap) == -1) {
if ((*ap)[0] == '-') {
if ((*ap)[1] == '\0')
ap++;
else if ((*ap)[1] == 'l' && (*ap)[2] == '\0') {
printsignals();
return 0;
}
else
error("bad option %s\n", *ap);
}
else
action = *ap++;
}
while (*ap) {
if (is_number(*ap))
signo = number(*ap);
else
signo = signame_to_signum(*ap);
if (signo < 0 || signo > NSIG)
error("%s: bad trap", *ap);
INTOFF;
if (action)
action = savestr(action);
if (trap[signo])
ckfree(trap[signo]);
trap[signo] = action;
if (signo != 0)
setsignal(signo, 0);
INTON;
ap++;
}
return 0;
}
/*
* Clear traps on a fork or vfork.
* Takes one arg vfork, to tell it to not be destructive of
* the parents variables.
*/
void
clear_traps(int vforked)
{
char **tp;
for (tp = trap ; tp <= &trap[NSIG] ; tp++) {
if (*tp && **tp) { /* trap not NULL or SIG_IGN */
INTOFF;
if (!vforked) {
ckfree(*tp);
*tp = NULL;
}
if (tp != &trap[0])
setsignal(tp - trap, vforked);
INTON;
}
}
}
/*
* Set the signal handler for the specified signal. The routine figures
* out what it should be set to.
*/
sig_t
setsignal(int signo, int vforked)
{
int action;
sig_t sigact = SIG_DFL, sig;
char *t, tsig;
if ((t = trap[signo]) == NULL)
action = S_DFL;
else if (*t != '\0')
action = S_CATCH;
else
action = S_IGN;
if (rootshell && !vforked && action == S_DFL) {
switch (signo) {
case SIGINT:
if (iflag || minusc || sflag == 0)
action = S_CATCH;
break;
case SIGQUIT:
#ifdef DEBUG
if (debug)
break;
#endif
/* FALLTHROUGH */
case SIGTERM:
if (iflag)
action = S_IGN;
break;
#if JOBS
case SIGTSTP:
case SIGTTOU:
if (mflag)
action = S_IGN;
break;
#endif
}
}
t = &sigmode[signo - 1];
tsig = *t;
if (tsig == 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 0;
}
if (sigact == SIG_IGN) {
/*
* POSIX 3.14.13 states that non-interactive shells
* should ignore trap commands for signals that were
* ignored upon entry, and leaves the behavior
* unspecified for interactive shells. On interactive
* shells, or if job control is on, and we have a job
* control related signal, we allow the trap to work.
*
* This change allows us to be POSIX compliant, and
* at the same time override the default behavior if
* we need to by setting the interactive flag.
*/
if ((mflag && (signo == SIGTSTP ||
signo == SIGTTIN || signo == SIGTTOU)) || iflag) {
tsig = S_IGN;
} else
tsig = S_HARD_IGN;
} else {
tsig = S_RESET; /* force to be set */
}
}
if (tsig == S_HARD_IGN || tsig == action)
return 0;
switch (action) {
case S_DFL: sigact = SIG_DFL; break;
case S_CATCH: sigact = onsig; break;
case S_IGN: sigact = SIG_IGN; break;
}
sig = signal(signo, sigact);
if (sig != SIG_ERR) {
sigset_t ss;
if (!vforked)
*t = action;
if (action == S_CATCH)
(void)siginterrupt(signo, 1);
/*
* If our parent accidentally blocked signals for
* us make sure we unblock them
*/
(void)sigemptyset(&ss);
(void)sigaddset(&ss, signo);
(void)sigprocmask(SIG_UNBLOCK, &ss, NULL);
}
return sig;
}
/*
* Return the current setting for sig w/o changing it.
*/
static int
getsigaction(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(int signo, int vforked)
{
if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
signal(signo, SIG_IGN);
}
if (!vforked)
sigmode[signo - 1] = S_HARD_IGN;
}
#ifdef mkinit
INCLUDE <signal.h>
INCLUDE "trap.h"
SHELLPROC {
char *sm;
clear_traps(0);
for (sm = sigmode ; sm < sigmode + NSIG ; sm++) {
if (*sm == S_IGN)
*sm = S_HARD_IGN;
}
}
#endif
/*
* Signal handler.
*/
void
onsig(int signo)
{
signal(signo, onsig);
if (signo == SIGINT && trap[SIGINT] == NULL) {
onint();
return;
}
gotsig[signo - 1] = 1;
pendingsigs++;
}
/*
* Called to execute a trap. Perhaps we should avoid entering new trap
* handlers while we are executing a trap handler.
*/
void
dotrap(void)
{
int i;
int savestatus;
for (;;) {
for (i = 1 ; ; i++) {
if (gotsig[i - 1])
break;
if (i >= NSIG)
goto done;
}
gotsig[i - 1] = 0;
savestatus=exitstatus;
evalstring(trap[i], 0);
exitstatus=savestatus;
}
done:
pendingsigs = 0;
}
/*
* Controls whether the shell is interactive or not.
*/
void
setinteractive(int on)
{
static int is_interactive;
if (on == is_interactive)
return;
setsignal(SIGINT, 0);
setsignal(SIGQUIT, 0);
setsignal(SIGTERM, 0);
is_interactive = on;
}
/*
* Called to exit the shell.
*/
void
exitshell(int status)
{
struct jmploc loc1, loc2;
char *p;
TRACE(("pid %d, exitshell(%d)\n", getpid(), status));
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, 0);
}
l1: handler = &loc2; /* probably unnecessary */
flushall();
#if JOBS
setjobctl(0);
#endif
l2: _exit(status);
/* NOTREACHED */
}