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Diffstat (limited to '')
| -rw-r--r-- | bin/1sh/trap.c | 553 |
1 files changed, 553 insertions, 0 deletions
diff --git a/bin/1sh/trap.c b/bin/1sh/trap.c new file mode 100644 index 00000000..93c063e1 --- /dev/null +++ b/bin/1sh/trap.c @@ -0,0 +1,553 @@ +/*- + * 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: releng/12.0/bin/sh/trap.c 326025 2017-11-20 19:49:47Z pfg $"); + +#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 < 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 < 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 == 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 < 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) { + /* + * The !in_dotrap here is safe. The only way we can arrive + * here with in_dotrap set is that a trap handler set SIGINT to + * SIG_DFL and killed itself. + */ + if (suppressint && !in_dotrap) + 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--; +} + + +/* + * Controls whether the shell is interactive or not based on iflag. + */ +void +setinteractive(void) +{ + setsignal(SIGINT); + setsignal(SIGQUIT); + 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); +} |