/*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1991, 1993 * 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. 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 #if 0 static char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95"; #endif #endif /* not lint */ #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); #include <signal.h> #include <unistd.h> #include <stdlib.h> #include "shell.h" #include "main.h" #include "nodes.h" /* for other headers */ #include "eval.h" #include "jobs.h" #include "show.h" #include "options.h" #include "syntax.h" #include "output.h" #include "memalloc.h" #include "error.h" #include "trap.h" #include "mystring.h" #include "builtins.h" #include "myhistedit.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 permanently */ #define S_RESET 5 /* temporary - to reset a hard ignored sig */ static char sigmode[NSIG]; /* current value of signal */ volatile sig_atomic_t pendingsig; /* indicates some signal received */ volatile sig_atomic_t pendingsig_waitcmd; /* indicates wait builtin should be interrupted */ static int in_dotrap; /* do we execute in a trap handler? */ static char *volatile trap[NSIG]; /* trap handler commands */ static volatile sig_atomic_t gotsig[NSIG]; /* indicates specified signal received */ static int ignore_sigchld; /* Used while handling SIGCHLD traps. */ static int last_trapsig; static int exiting; /* exitshell() has been called */ static int exiting_exitstatus; /* value passed to exitshell() */ static int getsigaction(int, sig_t *); /* * Map a string to a signal number. * * Note: the signal number may exceed NSIG. */ static int sigstring_to_signum(char *sig) { if (is_number(sig)) { int signo; signo = atoi(sig); return ((signo >= 0 && signo < NSIG) ? signo : (-1)); } else if (strcasecmp(sig, "EXIT") == 0) { return (0); } else { int n; if (strncasecmp(sig, "SIG", 3) == 0) sig += 3; for (n = 1; n < sys_nsig; n++) if (sys_signame[n] && strcasecmp(sys_signame[n], sig) == 0) return (n); } return (-1); } /* * Print a list of valid signal names. */ static void printsignals(void) { int n, outlen; outlen = 0; for (n = 1; n < sys_nsig; n++) { if (sys_signame[n]) { out1fmt("%s", sys_signame[n]); outlen += strlen(sys_signame[n]); } else { out1fmt("%d", n); outlen += 3; /* good enough */ } ++outlen; if (outlen > 71 || n == sys_nsig - 1) { out1str("\n"); outlen = 0; } else { out1c(' '); } } } /* * The trap builtin. */ int trapcmd(int argc __unused, char **argv) { char *action; int signo; int errors = 0; int i; while ((i = nextopt("l")) != '\0') { switch (i) { case 'l': printsignals(); return (0); } } argv = argptr; if (*argv == NULL) { for (signo = 0 ; signo < sys_nsig ; signo++) { if (signo < NSIG && trap[signo] != NULL) { out1str("trap -- "); out1qstr(trap[signo]); if (signo == 0) { out1str(" EXIT\n"); } else if (sys_signame[signo]) { out1fmt(" %s\n", sys_signame[signo]); } else { out1fmt(" %d\n", signo); } } } return 0; } action = NULL; if (*argv && !is_number(*argv)) { if (strcmp(*argv, "-") == 0) argv++; else { action = *argv; argv++; } } for (; *argv; argv++) { if ((signo = sigstring_to_signum(*argv)) == -1) { warning("bad signal %s", *argv); errors = 1; continue; } INTOFF; if (action) action = savestr(action); if (trap[signo]) ckfree(trap[signo]); trap[signo] = action; if (signo != 0) setsignal(signo); INTON; } return errors; } /* * Clear traps on a fork. */ void clear_traps(void) { char *volatile *tp; for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { if (*tp && **tp) { /* trap not NULL or SIG_IGN */ INTOFF; ckfree(*tp); *tp = NULL; if (tp != &trap[0]) setsignal(tp - trap); INTON; } } } /* * Check if we have any traps enabled. */ int have_traps(void) { char *volatile *tp; for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { if (*tp && **tp) /* trap not NULL or SIG_IGN */ return 1; } return 0; } /* * Set the signal handler for the specified signal. The routine figures * out what it should be set to. */ void setsignal(int signo) { int action; sig_t sigact = SIG_DFL; struct sigaction sa; char *t; if ((t = trap[signo]) == NULL) action = S_DFL; else if (*t != '\0') action = S_CATCH; else action = S_IGN; if (action == S_DFL) { switch (signo) { case SIGINT: action = S_CATCH; break; case SIGQUIT: #ifdef DEBUG { extern int debug; if (debug) break; } #endif action = S_CATCH; break; case SIGTERM: if (rootshell && iflag) action = S_IGN; break; #if JOBS case SIGTSTP: case SIGTTOU: if (rootshell && mflag) action = S_IGN; break; #endif } } t = &sigmode[signo]; if (*t == 0) { /* * current setting unknown */ if (!getsigaction(signo, &sigact)) { /* * Pretend it worked; maybe we should give a warning * here, but other shells don't. We don't alter * sigmode, so that we retry every time. */ return; } if (sigact == SIG_IGN) { if (mflag && (signo == SIGTSTP || signo == SIGTTIN || signo == SIGTTOU)) { *t = S_IGN; /* don't hard ignore these */ } else *t = S_HARD_IGN; } else { *t = S_RESET; /* force to be set */ } } if (*t == S_HARD_IGN || *t == action) return; switch (action) { case S_DFL: sigact = SIG_DFL; break; case S_CATCH: sigact = onsig; break; case S_IGN: sigact = SIG_IGN; break; } *t = action; sa.sa_handler = sigact; sa.sa_flags = 0; sigemptyset(&sa.sa_mask); sigaction(signo, &sa, NULL); } /* * Return the current setting for sig w/o changing it. */ static int getsigaction(int signo, sig_t *sigact) { struct sigaction sa; if (sigaction(signo, (struct sigaction *)0, &sa) == -1) return 0; *sigact = (sig_t) sa.sa_handler; return 1; } /* * Ignore a signal. */ void ignoresig(int signo) { if (sigmode[signo] == 0) setsignal(signo); if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) { signal(signo, SIG_IGN); sigmode[signo] = S_IGN; } } int issigchldtrapped(void) { return (trap[SIGCHLD] != NULL && *trap[SIGCHLD] != '\0'); } /* * Signal handler. */ void onsig(int signo) { if (signo == SIGINT && trap[SIGINT] == NULL) { if (suppressint) SET_PENDING_INT; else onint(); return; } /* If we are currently in a wait builtin, prepare to break it */ if (signo == SIGINT || signo == SIGQUIT) pendingsig_waitcmd = signo; if (trap[signo] != NULL && trap[signo][0] != '\0' && (signo != SIGCHLD || !ignore_sigchld)) { gotsig[signo] = 1; pendingsig = signo; pendingsig_waitcmd = signo; } } /* * Called to execute a trap. Perhaps we should avoid entering new trap * handlers while we are executing a trap handler. */ void dotrap(void) { struct stackmark smark; int i; int savestatus, prev_evalskip, prev_skipcount; in_dotrap++; for (;;) { pendingsig = 0; pendingsig_waitcmd = 0; for (i = 1; i < NSIG; i++) { if (gotsig[i]) { gotsig[i] = 0; if (trap[i]) { /* * Ignore SIGCHLD to avoid infinite * recursion if the trap action does * a fork. */ if (i == SIGCHLD) ignore_sigchld++; /* * Backup current evalskip * state and reset it before * executing a trap, so that the * trap is not disturbed by an * ongoing break/continue/return * statement. */ prev_evalskip = evalskip; prev_skipcount = skipcount; evalskip = 0; last_trapsig = i; savestatus = exitstatus; setstackmark(&smark); evalstring(stsavestr(trap[i]), 0); popstackmark(&smark); /* * If such a command was not * already in progress, allow a * break/continue/return in the * trap action to have an effect * outside of it. */ if (evalskip == 0 || prev_evalskip != 0) { evalskip = prev_evalskip; skipcount = prev_skipcount; exitstatus = savestatus; } if (i == SIGCHLD) ignore_sigchld--; } break; } } if (i >= NSIG) break; } in_dotrap--; } void trap_init(void) { setsignal(SIGINT); setsignal(SIGQUIT); } /* * Controls whether the shell is interactive or not based on iflag. */ void setinteractive(void) { setsignal(SIGTERM); } /* * Called to exit the shell. */ void exitshell(int status) { TRACE(("exitshell(%d) pid=%d\n", status, getpid())); exiting = 1; exiting_exitstatus = status; exitshell_savedstatus(); } void exitshell_savedstatus(void) { struct jmploc loc1, loc2; char *p; int sig = 0; sigset_t sigs; if (!exiting) { if (in_dotrap && last_trapsig) { sig = last_trapsig; exiting_exitstatus = sig + 128; } else exiting_exitstatus = oexitstatus; } exitstatus = oexitstatus = exiting_exitstatus; if (!setjmp(loc1.loc)) { handler = &loc1; if ((p = trap[0]) != NULL && *p != '\0') { /* * Reset evalskip, or the trap on EXIT could be * interrupted if the last command was a "return". */ evalskip = 0; trap[0] = NULL; FORCEINTON; evalstring(p, 0); } } if (!setjmp(loc2.loc)) { handler = &loc2; /* probably unnecessary */ FORCEINTON; flushall(); #if JOBS setjobctl(0); #endif } if (sig != 0 && sig != SIGSTOP && sig != SIGTSTP && sig != SIGTTIN && sig != SIGTTOU) { signal(sig, SIG_DFL); sigemptyset(&sigs); sigaddset(&sigs, sig); sigprocmask(SIG_UNBLOCK, &sigs, NULL); kill(getpid(), sig); /* If the default action is to ignore, fall back to _exit(). */ } _exit(exiting_exitstatus); }