minix/commands/ash/trap.c

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2005-04-21 16:53:53 +02:00
/*-
* Copyright (c) 1991 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
static char sccsid[] = "@(#)trap.c 5.2 (Berkeley) 4/12/91";
#endif /* not lint */
#include "shell.h"
#include "main.h"
#include "nodes.h" /* for other headers */
#include "eval.h"
#include "jobs.h"
#include "options.h"
#include "syntax.h"
#include "signames.h"
#include "output.h"
#include "memalloc.h"
#include "error.h"
#include "trap.h"
#include "mystring.h"
#include <sys/types.h>
#include <signal.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 */
extern char nullstr[1]; /* null string */
char *trap[MAXSIG+1]; /* trap handler commands */
MKINIT char sigmode[MAXSIG]; /* current value of signal */
char gotsig[MAXSIG]; /* indicates specified signal received */
int pendingsigs; /* indicates some signal received */
/*
* The trap builtin.
*/
trapcmd(argc, argv) char **argv; {
char *action;
char **ap;
int signo;
if (argc <= 1) {
for (signo = 0 ; signo <= MAXSIG ; signo++) {
if (trap[signo] != NULL)
out1fmt("%d: %s\n", signo, trap[signo]);
}
return 0;
}
ap = argv + 1;
if (is_number(*ap))
action = NULL;
else
action = *ap++;
while (*ap) {
if ((signo = number(*ap)) < 0 || signo > MAXSIG)
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);
INTON;
ap++;
}
return 0;
}
/*
* Clear traps on a fork.
*/
void
clear_traps() {
char **tp;
for (tp = trap ; tp <= &trap[MAXSIG] ; 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.
*/
int
setsignal(signo) {
int action;
sig_t sigact;
char *t;
extern void onsig();
if ((t = trap[signo]) == NULL)
action = S_DFL;
else if (*t != '\0')
action = S_CATCH;
else
action = S_IGN;
if (rootshell && action == S_DFL) {
switch (signo) {
case SIGINT:
if (iflag)
action = S_CATCH;
break;
case SIGQUIT:
#if DEBUG
{
extern int debug;
if (debug)
break;
}
#endif
/* FALLTHROUGH */
case SIGTERM:
if (iflag)
action = S_IGN;
break;
#if JOBS
case SIGTSTP:
case SIGTTOU:
if (jflag)
action = S_IGN;
break;
#endif
}
}
t = &sigmode[signo - 1];
if (*t == 0) { /* current setting unknown */
/*
* There is a race condition here if action is not S_IGN.
* A signal can be ignored that shouldn't be.
*/
if ((int)(sigact = signal(signo, SIG_IGN)) == -1)
error("Signal system call failed");
if (sigact == SIG_IGN) {
*t = S_HARD_IGN;
} else {
*t = S_IGN;
}
}
if (*t == S_HARD_IGN || *t == 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;
}
*t = action;
return (int)signal(signo, sigact);
}
/*
* Ignore a signal.
*/
void
ignoresig(signo) {
if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
signal(signo, SIG_IGN);
}
sigmode[signo - 1] = S_HARD_IGN;
}
#ifdef mkinit
INCLUDE "signames.h"
INCLUDE "trap.h"
SHELLPROC {
char *sm;
clear_traps();
for (sm = sigmode ; sm < sigmode + MAXSIG ; sm++) {
if (*sm == S_IGN)
*sm = S_HARD_IGN;
}
}
#endif
/*
* Signal handler.
*/
void
onsig(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() {
int i;
int savestatus;
for (;;) {
for (i = 1 ; ; i++) {
if (gotsig[i - 1])
break;
if (i >= MAXSIG)
goto done;
}
gotsig[i - 1] = 0;
savestatus=exitstatus;
evalstring(trap[i]);
exitstatus=savestatus;
}
done:
pendingsigs = 0;
}
/*
* Controls whether the shell is interactive or not.
*/
int is_interactive;
void
setinteractive(on) {
if (on == is_interactive)
return;
setsignal(SIGINT);
setsignal(SIGQUIT);
setsignal(SIGTERM);
is_interactive = on;
}
/*
* Called to exit the shell.
*/
void
exitshell(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);
}