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tg
451
trap.c
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451
trap.c
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@@ -0,0 +1,451 @@
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/* $OpenBSD: trap.c,v 1.13 2003/02/28 09:45:09 jmc Exp $ */
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/*
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* signal handling
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*/
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/* Kludge to avoid bogus re-declaration of sigtraps[] error on AIX 3.2.5 */
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#define FROM_TRAP_C
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#include "sh.h"
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/* Table is indexed by signal number
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*
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* The script siglist.sh generates siglist.out, which is a sorted, complete
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* list of signals
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*/
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Trap sigtraps[SIGNALS+1] = {
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{ SIGEXIT_, "EXIT", "Signal 0" },
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#include "siglist.out" /* generated by siglist.sh */
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{ SIGERR_, "ERR", "Error handler" },
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};
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static struct sigaction Sigact_ign, Sigact_trap;
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void
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inittraps()
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{
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#ifdef HAVE_SYS_SIGLIST
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# ifndef SYS_SIGLIST_DECLARED
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extern char *sys_siglist[];
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# endif
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int i;
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/* Use system description, if available, for unknown signals... */
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for (i = 0; i < NSIG; i++)
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if (!sigtraps[i].name && sys_siglist[i] && sys_siglist[i][0])
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sigtraps[i].mess = sys_siglist[i];
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#endif /* HAVE_SYS_SIGLIST */
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sigemptyset(&Sigact_ign.sa_mask);
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Sigact_ign.sa_flags = KSH_SA_FLAGS;
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Sigact_ign.sa_handler = SIG_IGN;
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Sigact_trap = Sigact_ign;
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Sigact_trap.sa_handler = trapsig;
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sigtraps[SIGINT].flags |= TF_DFL_INTR | TF_TTY_INTR;
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sigtraps[SIGQUIT].flags |= TF_DFL_INTR | TF_TTY_INTR;
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sigtraps[SIGTERM].flags |= TF_DFL_INTR;/* not fatal for interactive */
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sigtraps[SIGHUP].flags |= TF_FATAL;
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sigtraps[SIGCHLD].flags |= TF_SHELL_USES;
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/* these are always caught so we can clean up any temporary files. */
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setsig(&sigtraps[SIGINT], trapsig, SS_RESTORE_ORIG);
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setsig(&sigtraps[SIGQUIT], trapsig, SS_RESTORE_ORIG);
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setsig(&sigtraps[SIGTERM], trapsig, SS_RESTORE_ORIG);
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setsig(&sigtraps[SIGHUP], trapsig, SS_RESTORE_ORIG);
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}
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#ifdef KSH
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static RETSIGTYPE alarm_catcher ARGS((int sig));
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void
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alarm_init()
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{
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sigtraps[SIGALRM].flags |= TF_SHELL_USES;
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setsig(&sigtraps[SIGALRM], alarm_catcher,
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SS_RESTORE_ORIG|SS_FORCE|SS_SHTRAP);
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}
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static RETSIGTYPE
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alarm_catcher(sig)
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int sig;
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{
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int errno_ = errno;
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if (ksh_tmout_state == TMOUT_READING) {
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int left = alarm(0);
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if (left == 0) {
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ksh_tmout_state = TMOUT_LEAVING;
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intrsig = 1;
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} else
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alarm(left);
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}
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errno = errno_;
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return RETSIGVAL;
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}
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#endif /* KSH */
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Trap *
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gettrap(name, igncase)
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const char *name;
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int igncase;
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{
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int i;
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register Trap *p;
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if (digit(*name)) {
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int n;
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if (getn(name, &n) && 0 <= n && n < SIGNALS)
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return &sigtraps[n];
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return NULL;
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}
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for (p = sigtraps, i = SIGNALS+1; --i >= 0; p++)
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if (p->name) {
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if (igncase) {
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if (p->name && (!strcasecmp(p->name, name) ||
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(strlen(name) > 3 && !strncasecmp("SIG",
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p->name, 3) &&
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!strcasecmp(p->name, name + 3))))
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return p;
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} else {
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if (p->name && (!strcmp(p->name, name) ||
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(strlen(name) > 3 && !strncmp("SIG",
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p->name, 3) && !strcmp(p->name, name + 3))))
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return p;
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}
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}
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return NULL;
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}
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/*
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* trap signal handler
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*/
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RETSIGTYPE
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trapsig(i)
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int i;
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{
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Trap *p = &sigtraps[i];
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int errno_ = errno;
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trap = p->set = 1;
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if (p->flags & TF_DFL_INTR)
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intrsig = 1;
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if ((p->flags & TF_FATAL) && !p->trap) {
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fatal_trap = 1;
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intrsig = 1;
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}
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if (p->shtrap)
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(*p->shtrap)(i);
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#ifdef V7_SIGNALS
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if (sigtraps[i].cursig == trapsig) /* this for SIGCHLD,SIGALRM */
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sigaction(i, &Sigact_trap, (struct sigaction *) 0);
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#endif /* V7_SIGNALS */
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errno = errno_;
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return RETSIGVAL;
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}
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/* called when we want to allow the user to ^C out of something - won't
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* work if user has trapped SIGINT.
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*/
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void
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intrcheck()
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{
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if (intrsig)
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runtraps(TF_DFL_INTR|TF_FATAL);
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}
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/* called after EINTR to check if a signal with normally causes process
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* termination has been received.
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*/
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int
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fatal_trap_check()
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{
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int i;
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Trap *p;
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/* todo: should check if signal is fatal, not the TF_DFL_INTR flag */
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for (p = sigtraps, i = SIGNALS+1; --i >= 0; p++)
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if (p->set && (p->flags & (TF_DFL_INTR|TF_FATAL)))
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/* return value is used as an exit code */
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return 128 + p->signal;
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return 0;
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}
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/* Returns the signal number of any pending traps: ie, a signal which has
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* occurred for which a trap has been set or for which the TF_DFL_INTR flag
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* is set.
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*/
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int
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trap_pending()
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{
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int i;
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Trap *p;
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for (p = sigtraps, i = SIGNALS+1; --i >= 0; p++)
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if (p->set && ((p->trap && p->trap[0])
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|| ((p->flags & (TF_DFL_INTR|TF_FATAL))
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&& !p->trap)))
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return p->signal;
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return 0;
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}
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/*
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* run any pending traps. If intr is set, only run traps that
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* can interrupt commands.
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*/
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void
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runtraps(flag)
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int flag;
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{
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int i;
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register Trap *p;
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#ifdef KSH
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if (ksh_tmout_state == TMOUT_LEAVING) {
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ksh_tmout_state = TMOUT_EXECUTING;
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warningf(FALSE, "timed out waiting for input");
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unwind(LEXIT);
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} else
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/* XXX: this means the alarm will have no effect if a trap
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* is caught after the alarm() was started...not good.
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*/
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ksh_tmout_state = TMOUT_EXECUTING;
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#endif /* KSH */
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if (!flag)
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trap = 0;
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if (flag & TF_DFL_INTR)
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intrsig = 0;
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if (flag & TF_FATAL)
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fatal_trap = 0;
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for (p = sigtraps, i = SIGNALS+1; --i >= 0; p++)
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if (p->set && (!flag
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|| ((p->flags & flag) && p->trap == (char *) 0)))
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runtrap(p);
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}
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void
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runtrap(p)
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Trap *p;
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{
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int i = p->signal;
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char *trapstr = p->trap;
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int oexstat;
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int UNINITIALIZED(old_changed);
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p->set = 0;
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if (trapstr == (char *) 0) { /* SIG_DFL */
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if (p->flags & TF_FATAL) {
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/* eg, SIGHUP */
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exstat = 128 + i;
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unwind(LLEAVE);
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}
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if (p->flags & TF_DFL_INTR) {
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/* eg, SIGINT, SIGQUIT, SIGTERM, etc. */
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exstat = 128 + i;
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unwind(LINTR);
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}
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return;
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}
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if (trapstr[0] == '\0') /* SIG_IGN */
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return;
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if (i == SIGEXIT_ || i == SIGERR_) { /* avoid recursion on these */
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old_changed = p->flags & TF_CHANGED;
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p->flags &= ~TF_CHANGED;
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p->trap = (char *) 0;
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}
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oexstat = exstat;
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/* Note: trapstr is fully parsed before anything is executed, thus
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* no problem with afree(p->trap) in settrap() while still in use.
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*/
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command(trapstr);
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exstat = oexstat;
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if (i == SIGEXIT_ || i == SIGERR_) {
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if (p->flags & TF_CHANGED)
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/* don't clear TF_CHANGED */
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afree(trapstr, APERM);
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else
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p->trap = trapstr;
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p->flags |= old_changed;
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}
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}
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/* clear pending traps and reset user's trap handlers; used after fork(2) */
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void
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cleartraps()
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{
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int i;
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Trap *p;
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trap = 0;
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intrsig = 0;
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fatal_trap = 0;
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for (i = SIGNALS+1, p = sigtraps; --i >= 0; p++) {
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p->set = 0;
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if ((p->flags & TF_USER_SET) && (p->trap && p->trap[0]))
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settrap(p, (char *) 0);
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}
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}
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/* restore signals just before an exec(2) */
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void
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restoresigs()
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{
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int i;
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Trap *p;
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for (i = SIGNALS+1, p = sigtraps; --i >= 0; p++)
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if (p->flags & (TF_EXEC_IGN|TF_EXEC_DFL))
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setsig(p, (p->flags & TF_EXEC_IGN) ? SIG_IGN : SIG_DFL,
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SS_RESTORE_CURR|SS_FORCE);
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}
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void
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settrap(p, s)
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Trap *p;
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char *s;
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{
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handler_t f;
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if (p->trap)
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afree(p->trap, APERM);
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p->trap = str_save(s, APERM); /* handles s == 0 */
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p->flags |= TF_CHANGED;
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f = !s ? SIG_DFL : s[0] ? trapsig : SIG_IGN;
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p->flags |= TF_USER_SET;
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if ((p->flags & (TF_DFL_INTR|TF_FATAL)) && f == SIG_DFL)
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f = trapsig;
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else if (p->flags & TF_SHELL_USES) {
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if (!(p->flags & TF_ORIG_IGN) || Flag(FTALKING)) {
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/* do what user wants at exec time */
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p->flags &= ~(TF_EXEC_IGN|TF_EXEC_DFL);
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if (f == SIG_IGN)
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p->flags |= TF_EXEC_IGN;
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else
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p->flags |= TF_EXEC_DFL;
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}
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/* assumes handler already set to what shell wants it
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* (normally trapsig, but could be j_sigchld() or SIG_IGN)
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*/
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return;
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}
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/* todo: should we let user know signal is ignored? how? */
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setsig(p, f, SS_RESTORE_CURR|SS_USER);
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}
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/* Called by c_print() when writing to a co-process to ensure SIGPIPE won't
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* kill shell (unless user catches it and exits)
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*/
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int
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block_pipe()
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{
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int restore_dfl = 0;
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Trap *p = &sigtraps[SIGPIPE];
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if (!(p->flags & (TF_ORIG_IGN|TF_ORIG_DFL))) {
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setsig(p, SIG_IGN, SS_RESTORE_CURR);
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if (p->flags & TF_ORIG_DFL)
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restore_dfl = 1;
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} else if (p->cursig == SIG_DFL) {
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setsig(p, SIG_IGN, SS_RESTORE_CURR);
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restore_dfl = 1; /* restore to SIG_DFL */
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}
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return restore_dfl;
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}
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/* Called by c_print() to undo whatever block_pipe() did */
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void
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restore_pipe(restore_dfl)
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int restore_dfl;
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{
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if (restore_dfl)
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setsig(&sigtraps[SIGPIPE], SIG_DFL, SS_RESTORE_CURR);
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}
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/* Set action for a signal. Action may not be set if original
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* action was SIG_IGN, depending on the value of flags and
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* FTALKING.
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*/
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int
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setsig(p, f, flags)
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Trap *p;
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handler_t f;
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int flags;
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{
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struct sigaction sigact;
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if (p->signal == SIGEXIT_ || p->signal == SIGERR_)
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return 1;
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/* First time setting this signal? If so, get and note the current
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* setting.
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*/
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if (!(p->flags & (TF_ORIG_IGN|TF_ORIG_DFL))) {
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sigaction(p->signal, &Sigact_ign, &sigact);
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p->flags |= sigact.sa_handler == SIG_IGN ?
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TF_ORIG_IGN : TF_ORIG_DFL;
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p->cursig = SIG_IGN;
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}
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/* Generally, an ignored signal stays ignored, except if
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* - the user of an interactive shell wants to change it
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* - the shell wants for force a change
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*/
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if ((p->flags & TF_ORIG_IGN) && !(flags & SS_FORCE)
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&& (!(flags & SS_USER) || !Flag(FTALKING)))
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return 0;
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setexecsig(p, flags & SS_RESTORE_MASK);
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/* This is here 'cause there should be a way of clearing shtraps, but
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* don't know if this is a sane way of doing it. At the moment,
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* all users of shtrap are lifetime users (SIGCHLD, SIGALRM, SIGWINCH).
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*/
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if (!(flags & SS_USER))
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p->shtrap = (handler_t) 0;
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if (flags & SS_SHTRAP) {
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p->shtrap = f;
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f = trapsig;
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}
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if (p->cursig != f) {
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p->cursig = f;
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sigemptyset(&sigact.sa_mask);
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sigact.sa_flags = KSH_SA_FLAGS;
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sigact.sa_handler = f;
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sigaction(p->signal, &sigact, (struct sigaction *) 0);
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}
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return 1;
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}
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/* control what signal is set to before an exec() */
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void
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setexecsig(p, restore)
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Trap *p;
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int restore;
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{
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/* XXX debugging */
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if (!(p->flags & (TF_ORIG_IGN|TF_ORIG_DFL)))
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internal_errorf(1, "setexecsig: unset signal %d(%s)",
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p->signal, p->name);
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/* restore original value for exec'd kids */
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p->flags &= ~(TF_EXEC_IGN|TF_EXEC_DFL);
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switch (restore & SS_RESTORE_MASK) {
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case SS_RESTORE_CURR: /* leave things as they currently are */
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break;
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case SS_RESTORE_ORIG:
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p->flags |= p->flags & TF_ORIG_IGN ? TF_EXEC_IGN : TF_EXEC_DFL;
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break;
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case SS_RESTORE_DFL:
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p->flags |= TF_EXEC_DFL;
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break;
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case SS_RESTORE_IGN:
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p->flags |= TF_EXEC_IGN;
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break;
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}
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}
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