/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* 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.
*/
#ifndef lint
#if 0
static char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95";
#endif
#endif /* not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#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 "builtins.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 */
static char sigmode[NSIG]; /* current value of signal */
volatile sig_atomic_t pendingsig; /* indicates some signal received */
volatile sig_atomic_t pendingsig_waitcmd; /* indicates wait builtin should be interrupted */
static 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. */
static int last_trapsig;
static int exiting; /* exitshell() has been called */
static int exiting_exitstatus; /* value passed to exitshell() */
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 > 71 || n == sys_nsig - 1) {
out1str("\n");
outlen = 0;
} else {
out1c(' ');
}
}
}
/*
* The trap builtin.
*/
int
trapcmd(int argc __unused, char **argv)
{
char *action;
int signo;
int errors = 0;
int i;
while ((i = nextopt("l")) != '\0') {
switch (i) {
case 'l':
printsignals();
return (0);
}
}
argv = argptr;
if (*argv == NULL) {
for (signo = 0 ; signo < sys_nsig ; signo++) {
if (signo < NSIG && trap[signo] != NULL) {
out1str("trap -- ");
out1qstr(trap[signo]);
if (signo == 0) {
out1str(" EXIT\n");
} else if (sys_signame[signo]) {
out1fmt(" %s\n", sys_signame[signo]);
} else {
out1fmt(" %d\n", signo);
}
}
}
return 0;
}
action = NULL;
if (*argv && !is_number(*argv)) {
if (strcmp(*argv, "-") == 0)
argv++;
else {
action = *argv;
argv++;
}
}
for (; *argv; argv++) {
if ((signo = sigstring_to_signum(*argv)) == -1) {
warning("bad signal %s", *argv);
errors = 1;
continue;
}
INTOFF;
if (action)
action = savestr(action);
if (trap[signo])
ckfree(trap[signo]);
trap[signo] = action;
if (signo != 0)
setsignal(signo);
INTON;
}
return errors;
}
/*
* 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;
}
}
}
/*
* Check if we have any traps enabled.
*/
int
have_traps(void)
{
char *volatile *tp;
for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) {
if (*tp && **tp) /* trap not NULL or SIG_IGN */
return 1;
}
return 0;
}
/*
* 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 sigact = SIG_DFL;
struct sigaction sa;
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
}
}
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;
sa.sa_handler = sigact;
sa.sa_flags = 0;
sigemptyset(&sa.sa_mask);
sigaction(signo, &sa, NULL);
}
/*
* 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] == 0)
setsignal(signo);
if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) {
signal(signo, SIG_IGN);
sigmode[signo] = S_IGN;
}
}
int
issigchldtrapped(void)
{
return (trap[SIGCHLD] != NULL && *trap[SIGCHLD] != '\0');
}
/*
* Signal handler.
*/
void
onsig(int signo)
{
if (signo == SIGINT && trap[SIGINT] == NULL) {
if (suppressint)
SET_PENDING_INT;
else
onint();
return;
}
/* If we are currently in a wait builtin, prepare to break it */
if (signo == SIGINT || signo == SIGQUIT)
pendingsig_waitcmd = signo;
if (trap[signo] != NULL && trap[signo][0] != '\0' &&
(signo != SIGCHLD || !ignore_sigchld)) {
gotsig[signo] = 1;
pendingsig = signo;
pendingsig_waitcmd = signo;
}
}
/*
* Called to execute a trap. Perhaps we should avoid entering new trap
* handlers while we are executing a trap handler.
*/
void
dotrap(void)
{
struct stackmark smark;
int i;
int savestatus, prev_evalskip, prev_skipcount;
in_dotrap++;
for (;;) {
pendingsig = 0;
pendingsig_waitcmd = 0;
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++;
/*
* Backup current evalskip
* state and reset it before
* executing a trap, so that the
* trap is not disturbed by an
* ongoing break/continue/return
* statement.
*/
prev_evalskip = evalskip;
prev_skipcount = skipcount;
evalskip = 0;
last_trapsig = i;
savestatus = exitstatus;
setstackmark(&smark);
evalstring(stsavestr(trap[i]), 0);
popstackmark(&smark);
/*
* If such a command was not
* already in progress, allow a
* break/continue/return in the
* trap action to have an effect
* outside of it.
*/
if (evalskip == 0 ||
prev_evalskip != 0) {
evalskip = prev_evalskip;
skipcount = prev_skipcount;
exitstatus = savestatus;
}
if (i == SIGCHLD)
ignore_sigchld--;
}
break;
}
}
if (i >= NSIG)
break;
}
in_dotrap--;
}
void
trap_init(void)
{
setsignal(SIGINT);
setsignal(SIGQUIT);
}
/*
* Controls whether the shell is interactive or not based on iflag.
*/
void
setinteractive(void)
{
setsignal(SIGTERM);
}
/*
* Called to exit the shell.
*/
void
exitshell(int status)
{
TRACE(("exitshell(%d) pid=%d\n", status, getpid()));
exiting = 1;
exiting_exitstatus = status;
exitshell_savedstatus();
}
void
exitshell_savedstatus(void)
{
struct jmploc loc1, loc2;
char *p;
int sig = 0;
sigset_t sigs;
if (!exiting) {
if (in_dotrap && last_trapsig) {
sig = last_trapsig;
exiting_exitstatus = sig + 128;
} else
exiting_exitstatus = oexitstatus;
}
exitstatus = oexitstatus = exiting_exitstatus;
if (!setjmp(loc1.loc)) {
handler = &loc1;
if ((p = trap[0]) != NULL && *p != '\0') {
/*
* Reset evalskip, or the trap on EXIT could be
* interrupted if the last command was a "return".
*/
evalskip = 0;
trap[0] = NULL;
FORCEINTON;
evalstring(p, 0);
}
}
if (!setjmp(loc2.loc)) {
handler = &loc2; /* probably unnecessary */
FORCEINTON;
flushall();
#if JOBS
setjobctl(0);
#endif
}
if (sig != 0 && sig != SIGSTOP && sig != SIGTSTP && sig != SIGTTIN &&
sig != SIGTTOU) {
signal(sig, SIG_DFL);
sigemptyset(&sigs);
sigaddset(&sigs, sig);
sigprocmask(SIG_UNBLOCK, &sigs, NULL);
kill(getpid(), sig);
/* If the default action is to ignore, fall back to _exit(). */
}
_exit(exiting_exitstatus);
}
