1 /*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Kenneth Almquist. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #ifndef lint 34 #if 0 35 static char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95"; 36 #endif 37 #endif /* not lint */ 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include <signal.h> 42 #include <unistd.h> 43 #include <stdlib.h> 44 45 #include "shell.h" 46 #include "main.h" 47 #include "nodes.h" /* for other headers */ 48 #include "eval.h" 49 #include "jobs.h" 50 #include "show.h" 51 #include "options.h" 52 #include "syntax.h" 53 #include "output.h" 54 #include "memalloc.h" 55 #include "error.h" 56 #include "trap.h" 57 #include "mystring.h" 58 #include "builtins.h" 59 #include "myhistedit.h" 60 61 62 /* 63 * Sigmode records the current value of the signal handlers for the various 64 * modes. A value of zero means that the current handler is not known. 65 * S_HARD_IGN indicates that the signal was ignored on entry to the shell, 66 */ 67 68 #define S_DFL 1 /* default signal handling (SIG_DFL) */ 69 #define S_CATCH 2 /* signal is caught */ 70 #define S_IGN 3 /* signal is ignored (SIG_IGN) */ 71 #define S_HARD_IGN 4 /* signal is ignored permanently */ 72 #define S_RESET 5 /* temporary - to reset a hard ignored sig */ 73 74 75 static char sigmode[NSIG]; /* current value of signal */ 76 volatile sig_atomic_t pendingsig; /* indicates some signal received */ 77 volatile sig_atomic_t pendingsig_waitcmd; /* indicates SIGINT/SIGQUIT received */ 78 int in_dotrap; /* do we execute in a trap handler? */ 79 static char *volatile trap[NSIG]; /* trap handler commands */ 80 static volatile sig_atomic_t gotsig[NSIG]; 81 /* indicates specified signal received */ 82 static int ignore_sigchld; /* Used while handling SIGCHLD traps. */ 83 volatile sig_atomic_t gotwinch; 84 static int last_trapsig; 85 86 static int exiting; /* exitshell() has been called */ 87 static int exiting_exitstatus; /* value passed to exitshell() */ 88 89 static int getsigaction(int, sig_t *); 90 91 92 /* 93 * Map a string to a signal number. 94 * 95 * Note: the signal number may exceed NSIG. 96 */ 97 static int 98 sigstring_to_signum(char *sig) 99 { 100 101 if (is_number(sig)) { 102 int signo; 103 104 signo = atoi(sig); 105 return ((signo >= 0 && signo < NSIG) ? signo : (-1)); 106 } else if (strcasecmp(sig, "EXIT") == 0) { 107 return (0); 108 } else { 109 int n; 110 111 if (strncasecmp(sig, "SIG", 3) == 0) 112 sig += 3; 113 for (n = 1; n < sys_nsig; n++) 114 if (sys_signame[n] && 115 strcasecmp(sys_signame[n], sig) == 0) 116 return (n); 117 } 118 return (-1); 119 } 120 121 122 /* 123 * Print a list of valid signal names. 124 */ 125 static void 126 printsignals(void) 127 { 128 int n, outlen; 129 130 outlen = 0; 131 for (n = 1; n < sys_nsig; n++) { 132 if (sys_signame[n]) { 133 out1fmt("%s", sys_signame[n]); 134 outlen += strlen(sys_signame[n]); 135 } else { 136 out1fmt("%d", n); 137 outlen += 3; /* good enough */ 138 } 139 ++outlen; 140 if (outlen > 71 || n == sys_nsig - 1) { 141 out1str("\n"); 142 outlen = 0; 143 } else { 144 out1c(' '); 145 } 146 } 147 } 148 149 150 /* 151 * The trap builtin. 152 */ 153 int 154 trapcmd(int argc __unused, char **argv) 155 { 156 char *action; 157 int signo; 158 int errors = 0; 159 int i; 160 161 while ((i = nextopt("l")) != '\0') { 162 switch (i) { 163 case 'l': 164 printsignals(); 165 return (0); 166 } 167 } 168 argv = argptr; 169 170 if (*argv == NULL) { 171 for (signo = 0 ; signo < sys_nsig ; signo++) { 172 if (signo < NSIG && trap[signo] != NULL) { 173 out1str("trap -- "); 174 out1qstr(trap[signo]); 175 if (signo == 0) { 176 out1str(" EXIT\n"); 177 } else if (sys_signame[signo]) { 178 out1fmt(" %s\n", sys_signame[signo]); 179 } else { 180 out1fmt(" %d\n", signo); 181 } 182 } 183 } 184 return 0; 185 } 186 action = NULL; 187 if (*argv && sigstring_to_signum(*argv) == -1) { 188 if (strcmp(*argv, "-") == 0) 189 argv++; 190 else { 191 action = *argv; 192 argv++; 193 } 194 } 195 for (; *argv; argv++) { 196 if ((signo = sigstring_to_signum(*argv)) == -1) { 197 warning("bad signal %s", *argv); 198 errors = 1; 199 continue; 200 } 201 INTOFF; 202 if (action) 203 action = savestr(action); 204 if (trap[signo]) 205 ckfree(trap[signo]); 206 trap[signo] = action; 207 if (signo != 0) 208 setsignal(signo); 209 INTON; 210 } 211 return errors; 212 } 213 214 215 /* 216 * Clear traps on a fork. 217 */ 218 void 219 clear_traps(void) 220 { 221 char *volatile *tp; 222 223 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 224 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 225 INTOFF; 226 ckfree(*tp); 227 *tp = NULL; 228 if (tp != &trap[0]) 229 setsignal(tp - trap); 230 INTON; 231 } 232 } 233 } 234 235 236 /* 237 * Check if we have any traps enabled. 238 */ 239 int 240 have_traps(void) 241 { 242 char *volatile *tp; 243 244 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 245 if (*tp && **tp) /* trap not NULL or SIG_IGN */ 246 return 1; 247 } 248 return 0; 249 } 250 251 /* 252 * Set the signal handler for the specified signal. The routine figures 253 * out what it should be set to. 254 */ 255 void 256 setsignal(int signo) 257 { 258 int action; 259 sig_t sigact = SIG_DFL; 260 struct sigaction sa; 261 char *t; 262 263 if ((t = trap[signo]) == NULL) 264 action = S_DFL; 265 else if (*t != '\0') 266 action = S_CATCH; 267 else 268 action = S_IGN; 269 if (action == S_DFL) { 270 switch (signo) { 271 case SIGINT: 272 action = S_CATCH; 273 break; 274 case SIGQUIT: 275 #ifdef DEBUG 276 { 277 extern int debug; 278 279 if (debug) 280 break; 281 } 282 #endif 283 action = S_CATCH; 284 break; 285 case SIGTERM: 286 if (rootshell && iflag) 287 action = S_IGN; 288 break; 289 #if JOBS 290 case SIGTSTP: 291 case SIGTTOU: 292 if (rootshell && mflag) 293 action = S_IGN; 294 break; 295 #endif 296 #ifndef NO_HISTORY 297 case SIGWINCH: 298 if (rootshell && iflag) 299 action = S_CATCH; 300 break; 301 #endif 302 } 303 } 304 305 t = &sigmode[signo]; 306 if (*t == 0) { 307 /* 308 * current setting unknown 309 */ 310 if (!getsigaction(signo, &sigact)) { 311 /* 312 * Pretend it worked; maybe we should give a warning 313 * here, but other shells don't. We don't alter 314 * sigmode, so that we retry every time. 315 */ 316 return; 317 } 318 if (sigact == SIG_IGN) { 319 if (mflag && (signo == SIGTSTP || 320 signo == SIGTTIN || signo == SIGTTOU)) { 321 *t = S_IGN; /* don't hard ignore these */ 322 } else 323 *t = S_HARD_IGN; 324 } else { 325 *t = S_RESET; /* force to be set */ 326 } 327 } 328 if (*t == S_HARD_IGN || *t == action) 329 return; 330 switch (action) { 331 case S_DFL: sigact = SIG_DFL; break; 332 case S_CATCH: sigact = onsig; break; 333 case S_IGN: sigact = SIG_IGN; break; 334 } 335 *t = action; 336 sa.sa_handler = sigact; 337 sa.sa_flags = 0; 338 sigemptyset(&sa.sa_mask); 339 sigaction(signo, &sa, NULL); 340 } 341 342 343 /* 344 * Return the current setting for sig w/o changing it. 345 */ 346 static int 347 getsigaction(int signo, sig_t *sigact) 348 { 349 struct sigaction sa; 350 351 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 352 return 0; 353 *sigact = (sig_t) sa.sa_handler; 354 return 1; 355 } 356 357 358 /* 359 * Ignore a signal. 360 */ 361 void 362 ignoresig(int signo) 363 { 364 365 if (sigmode[signo] == 0) 366 setsignal(signo); 367 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) { 368 signal(signo, SIG_IGN); 369 sigmode[signo] = S_IGN; 370 } 371 } 372 373 374 int 375 issigchldtrapped(void) 376 { 377 378 return (trap[SIGCHLD] != NULL && *trap[SIGCHLD] != '\0'); 379 } 380 381 382 /* 383 * Signal handler. 384 */ 385 void 386 onsig(int signo) 387 { 388 389 if (signo == SIGINT && trap[SIGINT] == NULL) { 390 onint(); 391 return; 392 } 393 394 /* If we are currently in a wait builtin, prepare to break it */ 395 if (signo == SIGINT || signo == SIGQUIT) 396 pendingsig_waitcmd = signo; 397 398 if (trap[signo] != NULL && trap[signo][0] != '\0' && 399 (signo != SIGCHLD || !ignore_sigchld)) { 400 gotsig[signo] = 1; 401 pendingsig = signo; 402 } 403 404 #ifndef NO_HISTORY 405 if (signo == SIGWINCH) 406 gotwinch = 1; 407 #endif 408 } 409 410 411 /* 412 * Called to execute a trap. Perhaps we should avoid entering new trap 413 * handlers while we are executing a trap handler. 414 */ 415 void 416 dotrap(void) 417 { 418 int i; 419 int savestatus, prev_evalskip, prev_skipcount; 420 421 in_dotrap++; 422 for (;;) { 423 pendingsig = 0; 424 pendingsig_waitcmd = 0; 425 for (i = 1; i < NSIG; i++) { 426 if (gotsig[i]) { 427 gotsig[i] = 0; 428 if (trap[i]) { 429 /* 430 * Ignore SIGCHLD to avoid infinite 431 * recursion if the trap action does 432 * a fork. 433 */ 434 if (i == SIGCHLD) 435 ignore_sigchld++; 436 437 /* 438 * Backup current evalskip 439 * state and reset it before 440 * executing a trap, so that the 441 * trap is not disturbed by an 442 * ongoing break/continue/return 443 * statement. 444 */ 445 prev_evalskip = evalskip; 446 prev_skipcount = skipcount; 447 evalskip = 0; 448 449 last_trapsig = i; 450 savestatus = exitstatus; 451 evalstring(trap[i], 0); 452 453 /* 454 * If such a command was not 455 * already in progress, allow a 456 * break/continue/return in the 457 * trap action to have an effect 458 * outside of it. 459 */ 460 if (evalskip == 0 || 461 prev_evalskip != 0) { 462 evalskip = prev_evalskip; 463 skipcount = prev_skipcount; 464 exitstatus = savestatus; 465 } 466 467 if (i == SIGCHLD) 468 ignore_sigchld--; 469 } 470 break; 471 } 472 } 473 if (i >= NSIG) 474 break; 475 } 476 in_dotrap--; 477 } 478 479 480 /* 481 * Controls whether the shell is interactive or not. 482 */ 483 void 484 setinteractive(int on) 485 { 486 static int is_interactive = -1; 487 488 if (on == is_interactive) 489 return; 490 setsignal(SIGINT); 491 setsignal(SIGQUIT); 492 setsignal(SIGTERM); 493 #ifndef NO_HISTORY 494 setsignal(SIGWINCH); 495 #endif 496 is_interactive = on; 497 } 498 499 500 /* 501 * Called to exit the shell. 502 */ 503 void 504 exitshell(int status) 505 { 506 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 507 exiting = 1; 508 exiting_exitstatus = status; 509 exitshell_savedstatus(); 510 } 511 512 void 513 exitshell_savedstatus(void) 514 { 515 struct jmploc loc1, loc2; 516 char *p; 517 int sig = 0; 518 sigset_t sigs; 519 520 if (!exiting) { 521 if (in_dotrap && last_trapsig) { 522 sig = last_trapsig; 523 exiting_exitstatus = sig + 128; 524 } else 525 exiting_exitstatus = oexitstatus; 526 } 527 exitstatus = oexitstatus = exiting_exitstatus; 528 if (setjmp(loc1.loc)) { 529 goto l1; 530 } 531 if (setjmp(loc2.loc)) { 532 goto l2; 533 } 534 handler = &loc1; 535 if ((p = trap[0]) != NULL && *p != '\0') { 536 /* 537 * Reset evalskip, or the trap on EXIT could be 538 * interrupted if the last command was a "return". 539 */ 540 evalskip = 0; 541 trap[0] = NULL; 542 evalstring(p, 0); 543 } 544 l1: handler = &loc2; /* probably unnecessary */ 545 flushall(); 546 #if JOBS 547 setjobctl(0); 548 #endif 549 l2: 550 if (sig != 0 && sig != SIGSTOP && sig != SIGTSTP && sig != SIGTTIN && 551 sig != SIGTTOU) { 552 signal(sig, SIG_DFL); 553 sigemptyset(&sigs); 554 sigaddset(&sigs, sig); 555 sigprocmask(SIG_UNBLOCK, &sigs, NULL); 556 kill(getpid(), sig); 557 /* If the default action is to ignore, fall back to _exit(). */ 558 } 559 _exit(exiting_exitstatus); 560 } 561