+/*-
+ * 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.
+ *
+ * %sccs.include.redist.c%
+ */
+
+#ifndef lint
+static char sccsid[] = "@(#)trap.c 5.1 (Berkeley) %G%";
+#endif /* not lint */
+
+/*
+ * Routines for dealing with signals.
+ */
+
+#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 <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;
+#ifndef DEBUG
+ case SIGQUIT:
+#endif
+ 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;
+
+ for (;;) {
+ for (i = 1 ; ; i++) {
+ if (gotsig[i - 1])
+ break;
+ if (i >= MAXSIG)
+ goto done;
+ }
+ gotsig[i - 1] = 0;
+ evalstring(trap[i]);
+ }
+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);
+}
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