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36 * @(#)trap.c 8.5 (Berkeley) 6/5/95
37 * $FreeBSD: src/bin/sh/trap.c,v 1.48 2012/01/16 11:07:46 dumbbell Exp $
46 #include "nodes.h" /* for other headers */
58 #include "myhistedit.h"
62 * Sigmode records the current value of the signal handlers for the various
63 * modes. A value of zero means that the current handler is not known.
64 * S_HARD_IGN indicates that the signal was ignored on entry to the shell,
67 #define S_DFL 1 /* default signal handling (SIG_DFL) */
68 #define S_CATCH 2 /* signal is caught */
69 #define S_IGN 3 /* signal is ignored (SIG_IGN) */
70 #define S_HARD_IGN 4 /* signal is ignored permanently */
71 #define S_RESET 5 /* temporary - to reset a hard ignored sig */
74 MKINIT char sigmode[NSIG]; /* current value of signal */
75 int pendingsigs; /* indicates some signal received */
76 int in_dotrap; /* do we execute in a trap handler? */
77 static char *volatile trap[NSIG]; /* trap handler commands */
78 static volatile sig_atomic_t gotsig[NSIG];
79 /* indicates specified signal received */
80 static int ignore_sigchld; /* Used while handling SIGCHLD traps. */
81 volatile sig_atomic_t gotwinch;
82 static int last_trapsig;
84 static int exiting; /* exitshell() has been called */
85 static int exiting_exitstatus; /* value passed to exitshell() */
87 static int getsigaction(int, sig_t *);
91 * Map a string to a signal number.
93 * Note: the signal number may exceed NSIG.
96 sigstring_to_signum(char *sig)
103 return ((signo >= 0 && signo < NSIG) ? signo : (-1));
104 } else if (strcasecmp(sig, "EXIT") == 0) {
109 if (strncasecmp(sig, "SIG", 3) == 0)
111 for (n = 1; n < sys_nsig; n++)
112 if (sys_signame[n] &&
113 strcasecmp(sys_signame[n], sig) == 0)
121 * Print a list of valid signal names.
129 for (n = 1; n < sys_nsig; n++) {
130 if (sys_signame[n]) {
131 out1fmt("%s", sys_signame[n]);
132 outlen += strlen(sys_signame[n]);
135 outlen += 3; /* good enough */
138 if (outlen > 71 || n == sys_nsig - 1) {
152 trapcmd(int argc __unused, char **argv)
159 while ((i = nextopt("l")) != '\0') {
169 for (signo = 0 ; signo < sys_nsig ; signo++) {
170 if (signo < NSIG && trap[signo] != NULL) {
172 out1qstr(trap[signo]);
175 } else if (sys_signame[signo]) {
176 out1fmt(" %s\n", sys_signame[signo]);
178 out1fmt(" %d\n", signo);
185 if (*argv && sigstring_to_signum(*argv) == -1) {
186 if (strcmp(*argv, "-") == 0)
193 for (; *argv; argv++) {
194 if ((signo = sigstring_to_signum(*argv)) == -1) {
195 warning("bad signal %s", *argv);
201 action = savestr(action);
204 trap[signo] = action;
214 * Clear traps on a fork.
221 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) {
222 if (*tp && **tp) { /* trap not NULL or SIG_IGN */
227 setsignal(tp - trap);
235 * Check if we have any traps enabled.
242 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) {
243 if (*tp && **tp) /* trap not NULL or SIG_IGN */
250 * Set the signal handler for the specified signal. The routine figures
251 * out what it should be set to.
257 sig_t sigact = SIG_DFL;
261 if ((t = trap[signo]) == NULL)
267 if (action == S_DFL) {
284 if (rootshell && iflag)
290 if (rootshell && mflag)
296 if (rootshell && iflag)
306 * current setting unknown
308 if (!getsigaction(signo, &sigact)) {
310 * Pretend it worked; maybe we should give a warning
311 * here, but other shells don't. We don't alter
312 * sigmode, so that we retry every time.
316 if (sigact == SIG_IGN) {
317 if (mflag && (signo == SIGTSTP ||
318 signo == SIGTTIN || signo == SIGTTOU)) {
319 *t = S_IGN; /* don't hard ignore these */
323 *t = S_RESET; /* force to be set */
326 if (*t == S_HARD_IGN || *t == action)
329 case S_DFL: sigact = SIG_DFL; break;
330 case S_CATCH: sigact = onsig; break;
331 case S_IGN: sigact = SIG_IGN; break;
334 sa.sa_handler = sigact;
336 sigemptyset(&sa.sa_mask);
337 sigaction(signo, &sa, NULL);
342 * Return the current setting for sig w/o changing it.
345 getsigaction(int signo, sig_t *sigact)
349 if (sigaction(signo, NULL, &sa) == -1)
351 *sigact = (sig_t) sa.sa_handler;
363 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) {
364 signal(signo, SIG_IGN);
366 sigmode[signo] = S_HARD_IGN;
377 if (signo == SIGINT && trap[SIGINT] == NULL) {
382 if (signo != SIGCHLD || !ignore_sigchld)
386 /* If we are currently in a wait builtin, prepare to break it */
387 if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0)
390 * If a trap is set, not ignored and not the null command, we need
391 * to make sure traps are executed even when a child blocks signals.
394 trap[signo] != NULL &&
395 ! (trap[signo][0] == '\0') &&
396 ! (trap[signo][0] == ':' && trap[signo][1] == '\0'))
400 if (signo == SIGWINCH)
407 * Called to execute a trap. Perhaps we should avoid entering new trap
408 * handlers while we are executing a trap handler.
414 int savestatus, prev_evalskip, prev_skipcount;
418 for (i = 1; i < NSIG; i++) {
423 * Ignore SIGCHLD to avoid infinite
424 * recursion if the trap action does
431 * Backup current evalskip
432 * state and reset it before
433 * executing a trap, so that the
434 * trap is not disturbed by an
435 * ongoing break/continue/return
438 prev_evalskip = evalskip;
439 prev_skipcount = skipcount;
443 savestatus = exitstatus;
444 evalstring(trap[i], 0);
445 exitstatus = savestatus;
448 * If such a command was not
449 * already in progress, allow a
450 * break/continue/return in the
451 * trap action to have an effect
454 if (prev_evalskip != 0) {
455 evalskip = prev_evalskip;
456 skipcount = prev_skipcount;
474 * Controls whether the shell is interactive or not.
477 setinteractive(int on)
479 static int is_interactive = -1;
481 if (on == is_interactive)
494 * Called to exit the shell.
497 exitshell(int status)
499 TRACE(("exitshell(%d) pid=%d\n", status, getpid()));
501 exiting_exitstatus = status;
502 exitshell_savedstatus();
506 exitshell_savedstatus(void)
508 struct jmploc loc1, loc2;
510 volatile int sig = 0;
514 if (in_dotrap && last_trapsig) {
516 exiting_exitstatus = sig + 128;
518 exiting_exitstatus = oexitstatus;
520 exitstatus = oexitstatus = exiting_exitstatus;
521 if (setjmp(loc1.loc)) {
524 if (setjmp(loc2.loc)) {
528 if ((p = trap[0]) != NULL && *p != '\0') {
530 * Reset evalskip, or the trap on EXIT could be
531 * interrupted if the last command was a "return".
537 l1: handler = &loc2; /* probably unnecessary */
543 if (sig != 0 && sig != SIGSTOP && sig != SIGTSTP && sig != SIGTTIN &&
545 signal(sig, SIG_DFL);
547 sigaddset(&sigs, sig);
548 sigprocmask(SIG_UNBLOCK, &sigs, NULL);
550 /* If the default action is to ignore, fall back to _exit(). */
552 _exit(exiting_exitstatus);