FreeBSD-5.3/bin/sh/trap.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.
* 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
#endif /* not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/bin/sh/trap.c,v 1.29 2004/04/06 20:06:51 markm Exp $");
#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 "myhistedit.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 permanently */
#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; /* do we execute in a trap handler? */
static char *volatile 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. */
volatile sig_atomic_t gotwinch;
static int getsigaction(int, sig_t *);
/*
* Map a string to a signal number.
*
* Note: the signal number may exceed NSIG.
*/
static int
sigstring_to_signum(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 < sys_nsig; n++)
if (sys_signame[n] &&
strcasecmp(sys_signame[n], sig) == 0)
return (n);
}
return (-1);
}
/*
* Print a list of valid signal names.
*/
static void
printsignals(void)
{
int n, outlen;
outlen = 0;
for (n = 1; n < sys_nsig; n++) {
if (sys_signame[n]) {
out1fmt("%s", sys_signame[n]);
outlen += strlen(sys_signame[n]);
} else {
out1fmt("%d", n);
outlen += 3; /* good enough */
}
++outlen;
if (outlen > 70 || n == sys_nsig - 1) {
out1str("\n");
outlen = 0;
} else {
out1c(' ');
}
}
}
/*
* The trap builtin.
*/
int
trapcmd(int argc, char **argv)
{
char *action;
int signo;
if (argc <= 1) {
for (signo = 0 ; signo < sys_nsig ; signo++) {
if (signo < NSIG && trap[signo] != NULL) {
if (signo == 0) {
out1fmt("trap -- '%s' %s\n",
trap[signo], "exit");
} else if (sys_signame[signo]) {
out1fmt("trap -- '%s' %s\n",
trap[signo], sys_signame[signo]);
} else {
out1fmt("trap -- '%s' %d\n",
trap[signo], signo);
}
}
}
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(void)
{
char *volatile *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(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_CATCH;
break;
case SIGTERM:
if (rootshell && iflag)
action = S_IGN;
break;
#if JOBS
case SIGTSTP:
case SIGTTOU:
if (rootshell && mflag)
action = S_IGN;
break;
#endif
#ifndef NO_HISTORY
case SIGWINCH:
if (rootshell && iflag)
action = S_CATCH;
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);
if (sig != SIG_ERR && action == S_CATCH)
siginterrupt(signo, 1);
}
/*
* 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)
{
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(int signo)
{
if (signo == SIGINT && trap[SIGINT] == NULL) {
onint();
return;
}
if (signo != SIGCHLD || !ignore_sigchld)
gotsig[signo] = 1;
pendingsigs++;
/* If we are currently in a wait builtin, prepare to break it */
if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0)
breakwaitcmd = 1;
/*
* If a trap is set, not ignored and not the null command, we need
* to make sure traps are executed even when a child blocks signals.
*/
if (Tflag &&
trap[signo] != NULL &&
! trap[signo][0] == '\0' &&
! (trap[signo][0] == ':' && trap[signo][1] == '\0'))
breakwaitcmd = 1;
#ifndef NO_HISTORY
if (signo == SIGWINCH)
gotwinch = 1;
#endif
}
/*
* 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;
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(int on)
{
static int is_interactive = -1;
if (on == is_interactive)
return;
setsignal(SIGINT);
setsignal(SIGQUIT);
setsignal(SIGTERM);
#ifndef NO_HISTORY
setsignal(SIGWINCH);
#endif
is_interactive = on;
}
/*
* Called to exit the shell.
*/
void
exitshell(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);
}