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32 * @(#)trap.c 8.5 (Berkeley) 6/5/95
33 * $FreeBSD: head/bin/sh/trap.c 253658 2013-07-25 19:48:15Z jilles $
42 #include "nodes.h" /* for other headers */
54 #include "myhistedit.h"
58 * Sigmode records the current value of the signal handlers for the various
59 * modes. A value of zero means that the current handler is not known.
60 * S_HARD_IGN indicates that the signal was ignored on entry to the shell,
63 #define S_DFL 1 /* default signal handling (SIG_DFL) */
64 #define S_CATCH 2 /* signal is caught */
65 #define S_IGN 3 /* signal is ignored (SIG_IGN) */
66 #define S_HARD_IGN 4 /* signal is ignored permanently */
67 #define S_RESET 5 /* temporary - to reset a hard ignored sig */
70 static char sigmode[NSIG]; /* current value of signal */
71 volatile sig_atomic_t pendingsig; /* indicates some signal received */
72 int in_dotrap; /* do we execute in a trap handler? */
73 static char *volatile trap[NSIG]; /* trap handler commands */
74 static volatile sig_atomic_t gotsig[NSIG];
75 /* indicates specified signal received */
76 static int ignore_sigchld; /* Used while handling SIGCHLD traps. */
77 volatile sig_atomic_t gotwinch;
78 static int last_trapsig;
80 static int exiting; /* exitshell() has been called */
81 static int exiting_exitstatus; /* value passed to exitshell() */
83 static int getsigaction(int, sig_t *);
87 * Map a string to a signal number.
89 * Note: the signal number may exceed NSIG.
92 sigstring_to_signum(char *sig)
99 return ((signo >= 0 && signo < NSIG) ? signo : (-1));
100 } else if (strcasecmp(sig, "EXIT") == 0) {
105 if (strncasecmp(sig, "SIG", 3) == 0)
107 for (n = 1; n < sys_nsig; n++)
108 if (sys_signame[n] &&
109 strcasecmp(sys_signame[n], sig) == 0)
117 * Print a list of valid signal names.
125 for (n = 1; n < sys_nsig; n++) {
126 if (sys_signame[n]) {
127 out1fmt("%s", sys_signame[n]);
128 outlen += strlen(sys_signame[n]);
131 outlen += 3; /* good enough */
134 if (outlen > 71 || n == sys_nsig - 1) {
148 trapcmd(int argc __unused, char **argv)
155 while ((i = nextopt("l")) != '\0') {
165 for (signo = 0 ; signo < sys_nsig ; signo++) {
166 if (signo < NSIG && trap[signo] != NULL) {
168 out1qstr(trap[signo]);
171 } else if (sys_signame[signo]) {
172 out1fmt(" %s\n", sys_signame[signo]);
174 out1fmt(" %d\n", signo);
181 if (*argv && sigstring_to_signum(*argv) == -1) {
182 if (strcmp(*argv, "-") == 0)
189 for (; *argv; argv++) {
190 if ((signo = sigstring_to_signum(*argv)) == -1) {
191 warning("bad signal %s", *argv);
197 action = savestr(action);
200 trap[signo] = action;
210 * Clear traps on a fork.
217 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) {
218 if (*tp && **tp) { /* trap not NULL or SIG_IGN */
223 setsignal(tp - trap);
231 * Check if we have any traps enabled.
238 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) {
239 if (*tp && **tp) /* trap not NULL or SIG_IGN */
246 * Set the signal handler for the specified signal. The routine figures
247 * out what it should be set to.
253 sig_t sigact = SIG_DFL;
257 if ((t = trap[signo]) == NULL)
263 if (action == S_DFL) {
280 if (rootshell && iflag)
286 if (rootshell && mflag)
292 if (rootshell && iflag)
302 * current setting unknown
304 if (!getsigaction(signo, &sigact)) {
306 * Pretend it worked; maybe we should give a warning
307 * here, but other shells don't. We don't alter
308 * sigmode, so that we retry every time.
312 if (sigact == SIG_IGN) {
313 if (mflag && (signo == SIGTSTP ||
314 signo == SIGTTIN || signo == SIGTTOU)) {
315 *t = S_IGN; /* don't hard ignore these */
319 *t = S_RESET; /* force to be set */
322 if (*t == S_HARD_IGN || *t == action)
325 case S_DFL: sigact = SIG_DFL; break;
326 case S_CATCH: sigact = onsig; break;
327 case S_IGN: sigact = SIG_IGN; break;
330 sa.sa_handler = sigact;
332 sigemptyset(&sa.sa_mask);
333 sigaction(signo, &sa, NULL);
338 * Return the current setting for sig w/o changing it.
341 getsigaction(int signo, sig_t *sigact)
345 if (sigaction(signo, NULL, &sa) == -1)
347 *sigact = (sig_t) sa.sa_handler;
359 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) {
360 signal(signo, SIG_IGN);
362 sigmode[signo] = S_HARD_IGN;
367 issigchldtrapped(void)
370 return (trap[SIGCHLD] != NULL && *trap[SIGCHLD] != '\0');
381 if (signo == SIGINT && trap[SIGINT] == NULL) {
386 /* If we are currently in a wait builtin, prepare to break it */
387 if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0) {
392 if (trap[signo] != NULL && trap[signo][0] != '\0' &&
393 (signo != SIGCHLD || !ignore_sigchld)) {
398 * If a trap is set, not ignored and not the null command, we
399 * need to make sure traps are executed even when a child
402 if (Tflag && !(trap[signo][0] == ':' && trap[signo][1] == '\0'))
407 if (signo == SIGWINCH)
414 * Called to execute a trap. Perhaps we should avoid entering new trap
415 * handlers while we are executing a trap handler.
421 int savestatus, prev_evalskip, prev_skipcount;
426 for (i = 1; i < NSIG; i++) {
431 * Ignore SIGCHLD to avoid infinite
432 * recursion if the trap action does
439 * Backup current evalskip
440 * state and reset it before
441 * executing a trap, so that the
442 * trap is not disturbed by an
443 * ongoing break/continue/return
446 prev_evalskip = evalskip;
447 prev_skipcount = skipcount;
451 savestatus = exitstatus;
452 evalstring(trap[i], 0);
455 * If such a command was not
456 * already in progress, allow a
457 * break/continue/return in the
458 * trap action to have an effect
462 prev_evalskip != 0) {
463 evalskip = prev_evalskip;
464 skipcount = prev_skipcount;
465 exitstatus = savestatus;
482 * Controls whether the shell is interactive or not.
485 setinteractive(int on)
487 static int is_interactive = -1;
489 if (on == is_interactive)
502 * Called to exit the shell.
505 exitshell(int status)
507 TRACE(("exitshell(%d) pid=%d\n", status, getpid()));
509 exiting_exitstatus = status;
510 exitshell_savedstatus();
514 exitshell_savedstatus(void)
516 struct jmploc loc1, loc2;
518 volatile int sig = 0;
522 if (in_dotrap && last_trapsig) {
524 exiting_exitstatus = sig + 128;
526 exiting_exitstatus = oexitstatus;
528 exitstatus = oexitstatus = exiting_exitstatus;
529 if (setjmp(loc1.loc)) {
532 if (setjmp(loc2.loc)) {
536 if ((p = trap[0]) != NULL && *p != '\0') {
538 * Reset evalskip, or the trap on EXIT could be
539 * interrupted if the last command was a "return".
545 l1: handler = &loc2; /* probably unnecessary */
551 if (sig != 0 && sig != SIGSTOP && sig != SIGTSTP && sig != SIGTTIN &&
553 signal(sig, SIG_DFL);
555 sigaddset(&sigs, sig);
556 sigprocmask(SIG_UNBLOCK, &sigs, NULL);
558 /* If the default action is to ignore, fall back to _exit(). */
560 _exit(exiting_exitstatus);