trap.c revision 281718
1323124Sdes/*- 257429Smarkm * Copyright (c) 1991, 1993 357429Smarkm * The Regents of the University of California. All rights reserved. 457429Smarkm * 557429Smarkm * This code is derived from software contributed to Berkeley by 657429Smarkm * Kenneth Almquist. 757429Smarkm * 857429Smarkm * Redistribution and use in source and binary forms, with or without 960573Skris * modification, are permitted provided that the following conditions 1065668Skris * are met: 1165668Skris * 1. Redistributions of source code must retain the above copyright 1265668Skris * notice, this list of conditions and the following disclaimer. 1365668Skris * 2. Redistributions in binary form must reproduce the above copyright 1465668Skris * notice, this list of conditions and the following disclaimer in the 1557429Smarkm * documentation and/or other materials provided with the distribution. 1657429Smarkm * 4. Neither the name of the University nor the names of its contributors 1757429Smarkm * may be used to endorse or promote products derived from this software 1857429Smarkm * without specific prior written permission. 19162852Sdes * 20162852Sdes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21162852Sdes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22162852Sdes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23162852Sdes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24162852Sdes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25162852Sdes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26162852Sdes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27162852Sdes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28162852Sdes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29181111Sdes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30181111Sdes * SUCH DAMAGE. 31162852Sdes */ 3257429Smarkm 3357429Smarkm#ifndef lint 3476259Sgreen#if 0 3576259Sgreenstatic char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95"; 36295367Sdes#endif 37323124Sdes#endif /* not lint */ 38323124Sdes#include <sys/cdefs.h> 3957429Smarkm__FBSDID("$FreeBSD: head/bin/sh/trap.c 281718 2015-04-18 23:49:57Z bdrewery $"); 4076259Sgreen 41323124Sdes#include <signal.h> 42162852Sdes#include <unistd.h> 4376259Sgreen#include <stdlib.h> 4457429Smarkm 4576259Sgreen#include "shell.h" 4676259Sgreen#include "main.h" 4798675Sdes#include "nodes.h" /* for other headers */ 4876259Sgreen#include "eval.h" 4957429Smarkm#include "jobs.h" 5057429Smarkm#include "show.h" 5157429Smarkm#include "options.h" 5257429Smarkm#include "syntax.h" 5357429Smarkm#include "output.h" 5457429Smarkm#include "memalloc.h" 5592555Sdes#include "error.h" 5657429Smarkm#include "trap.h" 5757429Smarkm#include "mystring.h" 5857429Smarkm#include "builtins.h" 5957429Smarkm#include "myhistedit.h" 6057429Smarkm 61295367Sdes 62295367Sdes/* 63181111Sdes * Sigmode records the current value of the signal handlers for the various 64181111Sdes * modes. A value of zero means that the current handler is not known. 6557429Smarkm * S_HARD_IGN indicates that the signal was ignored on entry to the shell, 6657429Smarkm */ 67181111Sdes 6857429Smarkm#define S_DFL 1 /* default signal handling (SIG_DFL) */ 69181111Sdes#define S_CATCH 2 /* signal is caught */ 70181111Sdes#define S_IGN 3 /* signal is ignored (SIG_IGN) */ 71181111Sdes#define S_HARD_IGN 4 /* signal is ignored permanently */ 72181111Sdes#define S_RESET 5 /* temporary - to reset a hard ignored sig */ 73181111Sdes 74181111Sdes 75181111Sdesstatic char sigmode[NSIG]; /* current value of signal */ 76181111Sdesvolatile sig_atomic_t pendingsig; /* indicates some signal received */ 77181111Sdesvolatile sig_atomic_t pendingsig_waitcmd; /* indicates wait builtin should be interrupted */ 78181111Sdesstatic int in_dotrap; /* do we execute in a trap handler? */ 79181111Sdesstatic char *volatile trap[NSIG]; /* trap handler commands */ 80181111Sdesstatic volatile sig_atomic_t gotsig[NSIG]; 81181111Sdes /* indicates specified signal received */ 82181111Sdesstatic int ignore_sigchld; /* Used while handling SIGCHLD traps. */ 83181111Sdesstatic int last_trapsig; 8457429Smarkm 85295367Sdesstatic int exiting; /* exitshell() has been called */ 86295367Sdesstatic int exiting_exitstatus; /* value passed to exitshell() */ 87295367Sdes 8857429Smarkmstatic int getsigaction(int, sig_t *); 8957429Smarkm 9057429Smarkm 9157429Smarkm/* 9257429Smarkm * Map a string to a signal number. 9357429Smarkm * 9457429Smarkm * Note: the signal number may exceed NSIG. 9557429Smarkm */ 9657429Smarkmstatic int 9757429Smarkmsigstring_to_signum(char *sig) 9857429Smarkm{ 9957429Smarkm 10057429Smarkm if (is_number(sig)) { 10157429Smarkm int signo; 10257429Smarkm 10357429Smarkm signo = atoi(sig); 10457429Smarkm return ((signo >= 0 && signo < NSIG) ? signo : (-1)); 10557429Smarkm } else if (strcasecmp(sig, "EXIT") == 0) { 106124208Sdes return (0); 107124208Sdes } else { 10857429Smarkm int n; 10998675Sdes 11057429Smarkm if (strncasecmp(sig, "SIG", 3) == 0) 11157429Smarkm sig += 3; 11257429Smarkm for (n = 1; n < sys_nsig; n++) 11357429Smarkm if (sys_signame[n] && 11457429Smarkm strcasecmp(sys_signame[n], sig) == 0) 11557429Smarkm return (n); 11657429Smarkm } 11757429Smarkm return (-1); 11857429Smarkm} 11998675Sdes 12057429Smarkm 12157429Smarkm/* 12257429Smarkm * Print a list of valid signal names. 12357429Smarkm */ 12457429Smarkmstatic void 12557429Smarkmprintsignals(void) 12657429Smarkm{ 12757429Smarkm int n, outlen; 12857429Smarkm 12957429Smarkm outlen = 0; 13057429Smarkm for (n = 1; n < sys_nsig; n++) { 13157429Smarkm if (sys_signame[n]) { 13257429Smarkm out1fmt("%s", sys_signame[n]); 13357429Smarkm outlen += strlen(sys_signame[n]); 13457429Smarkm } else { 13557429Smarkm out1fmt("%d", n); 13657429Smarkm outlen += 3; /* good enough */ 13757429Smarkm } 13857429Smarkm ++outlen; 13957429Smarkm if (outlen > 71 || n == sys_nsig - 1) { 14057429Smarkm out1str("\n"); 14157429Smarkm outlen = 0; 14257429Smarkm } else { 14357429Smarkm out1c(' '); 14457429Smarkm } 14557429Smarkm } 146295367Sdes} 147295367Sdes 14857429Smarkm 14957429Smarkm/* 15057429Smarkm * The trap builtin. 15157429Smarkm */ 15257429Smarkmint 15357429Smarkmtrapcmd(int argc __unused, char **argv) 15457429Smarkm{ 155295367Sdes char *action; 156295367Sdes int signo; 15757429Smarkm int errors = 0; 15857429Smarkm int i; 15957429Smarkm 16057429Smarkm while ((i = nextopt("l")) != '\0') { 16157429Smarkm switch (i) { 16257429Smarkm case 'l': 16357429Smarkm printsignals(); 16457429Smarkm return (0); 16557429Smarkm } 16657429Smarkm } 16757429Smarkm argv = argptr; 16857429Smarkm 16957429Smarkm if (*argv == NULL) { 17057429Smarkm for (signo = 0 ; signo < sys_nsig ; signo++) { 17198675Sdes if (signo < NSIG && trap[signo] != NULL) { 172149749Sdes out1str("trap -- "); 17357429Smarkm out1qstr(trap[signo]); 17457429Smarkm if (signo == 0) { 17557429Smarkm out1str(" EXIT\n"); 17657429Smarkm } else if (sys_signame[signo]) { 17757429Smarkm out1fmt(" %s\n", sys_signame[signo]); 17857429Smarkm } else { 17957429Smarkm out1fmt(" %d\n", signo); 18057429Smarkm } 18157429Smarkm } 18257429Smarkm } 18357429Smarkm return 0; 18457429Smarkm } 18557429Smarkm action = NULL; 18657429Smarkm if (*argv && !is_number(*argv)) { 18757429Smarkm if (strcmp(*argv, "-") == 0) 18857429Smarkm argv++; 18957429Smarkm else { 19060573Skris action = *argv; 19157429Smarkm argv++; 19257429Smarkm } 193323124Sdes } 19476259Sgreen for (; *argv; argv++) { 19576259Sgreen if ((signo = sigstring_to_signum(*argv)) == -1) { 196323124Sdes warning("bad signal %s", *argv); 197323124Sdes errors = 1; 19898675Sdes continue; 19976259Sgreen } 20076259Sgreen INTOFF; 20198675Sdes if (action) 20298675Sdes action = savestr(action); 20376259Sgreen if (trap[signo]) 20476259Sgreen ckfree(trap[signo]); 20557429Smarkm trap[signo] = action; 20657429Smarkm if (signo != 0) 20757429Smarkm setsignal(signo); 20876259Sgreen INTON; 20957429Smarkm } 21076259Sgreen return errors; 21176259Sgreen} 21276259Sgreen 21357429Smarkm 21476259Sgreen/* 21557429Smarkm * Clear traps on a fork. 216295367Sdes */ 217295367Sdesvoid 21857429Smarkmclear_traps(void) 21957429Smarkm{ 22057429Smarkm char *volatile *tp; 22157429Smarkm 22292555Sdes for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 22357429Smarkm if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 22457429Smarkm INTOFF; 22557429Smarkm ckfree(*tp); 22657429Smarkm *tp = NULL; 22757429Smarkm if (tp != &trap[0]) 22857429Smarkm setsignal(tp - trap); 22957429Smarkm INTON; 23057429Smarkm } 23157429Smarkm } 232295367Sdes} 233295367Sdes 234295367Sdes 235295367Sdes/* 23657429Smarkm * Check if we have any traps enabled. 23776259Sgreen */ 238295367Sdesint 239295367Sdeshave_traps(void) 24057429Smarkm{ 241295367Sdes char *volatile *tp; 24257429Smarkm 243295367Sdes for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 244295367Sdes if (*tp && **tp) /* trap not NULL or SIG_IGN */ 245295367Sdes return 1; 246295367Sdes } 247295367Sdes return 0; 248295367Sdes} 249295367Sdes 25092555Sdes/* 25192555Sdes * Set the signal handler for the specified signal. The routine figures 252295367Sdes * out what it should be set to. 253295367Sdes */ 25457429Smarkmvoid 25557429Smarkmsetsignal(int signo) 25692555Sdes{ 25792555Sdes int action; 258295367Sdes sig_t sigact = SIG_DFL; 259295367Sdes struct sigaction sa; 26057429Smarkm char *t; 26157429Smarkm 26257429Smarkm if ((t = trap[signo]) == NULL) 263295367Sdes action = S_DFL; 26457429Smarkm else if (*t != '\0') 26557429Smarkm action = S_CATCH; 26657429Smarkm else 26757429Smarkm action = S_IGN; 26857429Smarkm if (action == S_DFL) { 269124208Sdes switch (signo) { 27098675Sdes case SIGINT: 27198675Sdes action = S_CATCH; 27298675Sdes break; 27357429Smarkm case SIGQUIT: 27457429Smarkm#ifdef DEBUG 27557429Smarkm { 27657429Smarkm extern int debug; 27792555Sdes 278124208Sdes if (debug) 27998675Sdes break; 28098675Sdes } 28198675Sdes#endif 28257429Smarkm action = S_CATCH; 28357429Smarkm break; 28457429Smarkm case SIGTERM: 28576259Sgreen if (rootshell && iflag) 28657429Smarkm action = S_IGN; 28757429Smarkm break; 28857429Smarkm#if JOBS 28992555Sdes case SIGTSTP: 29057429Smarkm case SIGTTOU: 29157429Smarkm if (rootshell && mflag) 29257429Smarkm action = S_IGN; 29357429Smarkm break; 29457429Smarkm#endif 29557429Smarkm } 29657429Smarkm } 29757429Smarkm 29857429Smarkm t = &sigmode[signo]; 29957429Smarkm if (*t == 0) { 30057429Smarkm /* 30157429Smarkm * current setting unknown 30257429Smarkm */ 30357429Smarkm if (!getsigaction(signo, &sigact)) { 30492555Sdes /* 305124208Sdes * Pretend it worked; maybe we should give a warning 30657429Smarkm * here, but other shells don't. We don't alter 30798675Sdes * sigmode, so that we retry every time. 30857429Smarkm */ 30957429Smarkm return; 310295367Sdes } 311295367Sdes if (sigact == SIG_IGN) { 312295367Sdes if (mflag && (signo == SIGTSTP || 313295367Sdes signo == SIGTTIN || signo == SIGTTOU)) { 31457429Smarkm *t = S_IGN; /* don't hard ignore these */ 315295367Sdes } else 316295367Sdes *t = S_HARD_IGN; 31757429Smarkm } else { 31857429Smarkm *t = S_RESET; /* force to be set */ 31957429Smarkm } 320295367Sdes } 321295367Sdes if (*t == S_HARD_IGN || *t == action) 32298675Sdes return; 32398675Sdes switch (action) { 32457429Smarkm case S_DFL: sigact = SIG_DFL; break; 32557429Smarkm case S_CATCH: sigact = onsig; break; 326295367Sdes case S_IGN: sigact = SIG_IGN; break; 327295367Sdes } 328295367Sdes *t = action; 32957429Smarkm sa.sa_handler = sigact; 33057429Smarkm sa.sa_flags = 0; 33157429Smarkm sigemptyset(&sa.sa_mask); 33257429Smarkm sigaction(signo, &sa, NULL); 33357429Smarkm} 33457429Smarkm 33557429Smarkm 33657429Smarkm/* 33798675Sdes * Return the current setting for sig w/o changing it. 33898675Sdes */ 33998675Sdesstatic int 34098675Sdesgetsigaction(int signo, sig_t *sigact) 34198675Sdes{ 342204917Sdes struct sigaction sa; 34398675Sdes 344 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 345 return 0; 346 *sigact = (sig_t) sa.sa_handler; 347 return 1; 348} 349 350 351/* 352 * Ignore a signal. 353 */ 354void 355ignoresig(int signo) 356{ 357 358 if (sigmode[signo] == 0) 359 setsignal(signo); 360 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) { 361 signal(signo, SIG_IGN); 362 sigmode[signo] = S_IGN; 363 } 364} 365 366 367int 368issigchldtrapped(void) 369{ 370 371 return (trap[SIGCHLD] != NULL && *trap[SIGCHLD] != '\0'); 372} 373 374 375/* 376 * Signal handler. 377 */ 378void 379onsig(int signo) 380{ 381 382 if (signo == SIGINT && trap[SIGINT] == NULL) { 383 /* 384 * The !in_dotrap here is safe. The only way we can arrive 385 * here with in_dotrap set is that a trap handler set SIGINT to 386 * SIG_DFL and killed itself. 387 */ 388 if (suppressint && !in_dotrap) 389 SET_PENDING_INT; 390 else 391 onint(); 392 return; 393 } 394 395 /* If we are currently in a wait builtin, prepare to break it */ 396 if (signo == SIGINT || signo == SIGQUIT) 397 pendingsig_waitcmd = signo; 398 399 if (trap[signo] != NULL && trap[signo][0] != '\0' && 400 (signo != SIGCHLD || !ignore_sigchld)) { 401 gotsig[signo] = 1; 402 pendingsig = signo; 403 pendingsig_waitcmd = signo; 404 } 405} 406 407 408/* 409 * Called to execute a trap. Perhaps we should avoid entering new trap 410 * handlers while we are executing a trap handler. 411 */ 412void 413dotrap(void) 414{ 415 int i; 416 int savestatus, prev_evalskip, prev_skipcount; 417 418 in_dotrap++; 419 for (;;) { 420 pendingsig = 0; 421 pendingsig_waitcmd = 0; 422 for (i = 1; i < NSIG; i++) { 423 if (gotsig[i]) { 424 gotsig[i] = 0; 425 if (trap[i]) { 426 /* 427 * Ignore SIGCHLD to avoid infinite 428 * recursion if the trap action does 429 * a fork. 430 */ 431 if (i == SIGCHLD) 432 ignore_sigchld++; 433 434 /* 435 * Backup current evalskip 436 * state and reset it before 437 * executing a trap, so that the 438 * trap is not disturbed by an 439 * ongoing break/continue/return 440 * statement. 441 */ 442 prev_evalskip = evalskip; 443 prev_skipcount = skipcount; 444 evalskip = 0; 445 446 last_trapsig = i; 447 savestatus = exitstatus; 448 evalstring(trap[i], 0); 449 450 /* 451 * If such a command was not 452 * already in progress, allow a 453 * break/continue/return in the 454 * trap action to have an effect 455 * outside of it. 456 */ 457 if (evalskip == 0 || 458 prev_evalskip != 0) { 459 evalskip = prev_evalskip; 460 skipcount = prev_skipcount; 461 exitstatus = savestatus; 462 } 463 464 if (i == SIGCHLD) 465 ignore_sigchld--; 466 } 467 break; 468 } 469 } 470 if (i >= NSIG) 471 break; 472 } 473 in_dotrap--; 474} 475 476 477/* 478 * Controls whether the shell is interactive or not. 479 */ 480void 481setinteractive(int on) 482{ 483 static int is_interactive = -1; 484 485 if (on == is_interactive) 486 return; 487 setsignal(SIGINT); 488 setsignal(SIGQUIT); 489 setsignal(SIGTERM); 490 is_interactive = on; 491} 492 493 494/* 495 * Called to exit the shell. 496 */ 497void 498exitshell(int status) 499{ 500 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 501 exiting = 1; 502 exiting_exitstatus = status; 503 exitshell_savedstatus(); 504} 505 506void 507exitshell_savedstatus(void) 508{ 509 struct jmploc loc1, loc2; 510 char *p; 511 int sig = 0; 512 sigset_t sigs; 513 514 if (!exiting) { 515 if (in_dotrap && last_trapsig) { 516 sig = last_trapsig; 517 exiting_exitstatus = sig + 128; 518 } else 519 exiting_exitstatus = oexitstatus; 520 } 521 exitstatus = oexitstatus = exiting_exitstatus; 522 if (!setjmp(loc1.loc)) { 523 handler = &loc1; 524 if ((p = trap[0]) != NULL && *p != '\0') { 525 /* 526 * Reset evalskip, or the trap on EXIT could be 527 * interrupted if the last command was a "return". 528 */ 529 evalskip = 0; 530 trap[0] = NULL; 531 evalstring(p, 0); 532 } 533 } 534 if (!setjmp(loc2.loc)) { 535 handler = &loc2; /* probably unnecessary */ 536 flushall(); 537#if JOBS 538 setjobctl(0); 539#endif 540 } 541 if (sig != 0 && sig != SIGSTOP && sig != SIGTSTP && sig != SIGTTIN && 542 sig != SIGTTOU) { 543 signal(sig, SIG_DFL); 544 sigemptyset(&sigs); 545 sigaddset(&sigs, sig); 546 sigprocmask(SIG_UNBLOCK, &sigs, NULL); 547 kill(getpid(), sig); 548 /* If the default action is to ignore, fall back to _exit(). */ 549 } 550 _exit(exiting_exitstatus); 551} 552