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 * 3. 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 wait builtin should be interrupted */ 78 static 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 static int last_trapsig; 84 85 static int exiting; /* exitshell() has been called */ 86 static int exiting_exitstatus; /* value passed to exitshell() */ 87 88 static int getsigaction(int, sig_t *); 89 90 91 /* 92 * Map a string to a signal number. 93 * 94 * Note: the signal number may exceed NSIG. 95 */ 96 static int 97 sigstring_to_signum(char *sig) 98 { 99 100 if (is_number(sig)) { 101 int signo; 102 103 signo = atoi(sig); 104 return ((signo >= 0 && signo < NSIG) ? signo : (-1)); 105 } else if (strcasecmp(sig, "EXIT") == 0) { 106 return (0); 107 } else { 108 int n; 109 110 if (strncasecmp(sig, "SIG", 3) == 0) 111 sig += 3; 112 for (n = 1; n < sys_nsig; n++) 113 if (sys_signame[n] && 114 strcasecmp(sys_signame[n], sig) == 0) 115 return (n); 116 } 117 return (-1); 118 } 119 120 121 /* 122 * Print a list of valid signal names. 123 */ 124 static void 125 printsignals(void) 126 { 127 int n, outlen; 128 129 outlen = 0; 130 for (n = 1; n < sys_nsig; n++) { 131 if (sys_signame[n]) { 132 out1fmt("%s", sys_signame[n]); 133 outlen += strlen(sys_signame[n]); 134 } else { 135 out1fmt("%d", n); 136 outlen += 3; /* good enough */ 137 } 138 ++outlen; 139 if (outlen > 71 || n == sys_nsig - 1) { 140 out1str("\n"); 141 outlen = 0; 142 } else { 143 out1c(' '); 144 } 145 } 146 } 147 148 149 /* 150 * The trap builtin. 151 */ 152 int 153 trapcmd(int argc __unused, char **argv) 154 { 155 char *action; 156 int signo; 157 int errors = 0; 158 int i; 159 160 while ((i = nextopt("l")) != '\0') { 161 switch (i) { 162 case 'l': 163 printsignals(); 164 return (0); 165 } 166 } 167 argv = argptr; 168 169 if (*argv == NULL) { 170 for (signo = 0 ; signo < sys_nsig ; signo++) { 171 if (signo < NSIG && trap[signo] != NULL) { 172 out1str("trap -- "); 173 out1qstr(trap[signo]); 174 if (signo == 0) { 175 out1str(" EXIT\n"); 176 } else if (sys_signame[signo]) { 177 out1fmt(" %s\n", sys_signame[signo]); 178 } else { 179 out1fmt(" %d\n", signo); 180 } 181 } 182 } 183 return 0; 184 } 185 action = NULL; 186 if (*argv && !is_number(*argv)) { 187 if (strcmp(*argv, "-") == 0) 188 argv++; 189 else { 190 action = *argv; 191 argv++; 192 } 193 } 194 for (; *argv; argv++) { 195 if ((signo = sigstring_to_signum(*argv)) == -1) { 196 warning("bad signal %s", *argv); 197 errors = 1; 198 continue; 199 } 200 INTOFF; 201 if (action) 202 action = savestr(action); 203 if (trap[signo]) 204 ckfree(trap[signo]); 205 trap[signo] = action; 206 if (signo != 0) 207 setsignal(signo); 208 INTON; 209 } 210 return errors; 211 } 212 213 214 /* 215 * Clear traps on a fork. 216 */ 217 void 218 clear_traps(void) 219 { 220 char *volatile *tp; 221 222 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 223 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 224 INTOFF; 225 ckfree(*tp); 226 *tp = NULL; 227 if (tp != &trap[0]) 228 setsignal(tp - trap); 229 INTON; 230 } 231 } 232 } 233 234 235 /* 236 * Check if we have any traps enabled. 237 */ 238 int 239 have_traps(void) 240 { 241 char *volatile *tp; 242 243 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 244 if (*tp && **tp) /* trap not NULL or SIG_IGN */ 245 return 1; 246 } 247 return 0; 248 } 249 250 /* 251 * Set the signal handler for the specified signal. The routine figures 252 * out what it should be set to. 253 */ 254 void 255 setsignal(int signo) 256 { 257 int action; 258 sig_t sigact = SIG_DFL; 259 struct sigaction sa; 260 char *t; 261 262 if ((t = trap[signo]) == NULL) 263 action = S_DFL; 264 else if (*t != '\0') 265 action = S_CATCH; 266 else 267 action = S_IGN; 268 if (action == S_DFL) { 269 switch (signo) { 270 case SIGINT: 271 action = S_CATCH; 272 break; 273 case SIGQUIT: 274 #ifdef DEBUG 275 { 276 extern int debug; 277 278 if (debug) 279 break; 280 } 281 #endif 282 action = S_CATCH; 283 break; 284 case SIGTERM: 285 if (rootshell && iflag) 286 action = S_IGN; 287 break; 288 #if JOBS 289 case SIGTSTP: 290 case SIGTTOU: 291 if (rootshell && mflag) 292 action = S_IGN; 293 break; 294 #endif 295 } 296 } 297 298 t = &sigmode[signo]; 299 if (*t == 0) { 300 /* 301 * current setting unknown 302 */ 303 if (!getsigaction(signo, &sigact)) { 304 /* 305 * Pretend it worked; maybe we should give a warning 306 * here, but other shells don't. We don't alter 307 * sigmode, so that we retry every time. 308 */ 309 return; 310 } 311 if (sigact == SIG_IGN) { 312 if (mflag && (signo == SIGTSTP || 313 signo == SIGTTIN || signo == SIGTTOU)) { 314 *t = S_IGN; /* don't hard ignore these */ 315 } else 316 *t = S_HARD_IGN; 317 } else { 318 *t = S_RESET; /* force to be set */ 319 } 320 } 321 if (*t == S_HARD_IGN || *t == action) 322 return; 323 switch (action) { 324 case S_DFL: sigact = SIG_DFL; break; 325 case S_CATCH: sigact = onsig; break; 326 case S_IGN: sigact = SIG_IGN; break; 327 } 328 *t = action; 329 sa.sa_handler = sigact; 330 sa.sa_flags = 0; 331 sigemptyset(&sa.sa_mask); 332 sigaction(signo, &sa, NULL); 333 } 334 335 336 /* 337 * Return the current setting for sig w/o changing it. 338 */ 339 static int 340 getsigaction(int signo, sig_t *sigact) 341 { 342 struct sigaction sa; 343 344 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 */ 354 void 355 ignoresig(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 } 365 366 367 int 368 issigchldtrapped(void) 369 { 370 371 return (trap[SIGCHLD] != NULL && *trap[SIGCHLD] != '\0'); 372 } 373 374 375 /* 376 * Signal handler. 377 */ 378 void 379 onsig(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 */ 412 void 413 dotrap(void) 414 { 415 struct stackmark smark; 416 int i; 417 int savestatus, prev_evalskip, prev_skipcount; 418 419 in_dotrap++; 420 for (;;) { 421 pendingsig = 0; 422 pendingsig_waitcmd = 0; 423 for (i = 1; i < NSIG; i++) { 424 if (gotsig[i]) { 425 gotsig[i] = 0; 426 if (trap[i]) { 427 /* 428 * Ignore SIGCHLD to avoid infinite 429 * recursion if the trap action does 430 * a fork. 431 */ 432 if (i == SIGCHLD) 433 ignore_sigchld++; 434 435 /* 436 * Backup current evalskip 437 * state and reset it before 438 * executing a trap, so that the 439 * trap is not disturbed by an 440 * ongoing break/continue/return 441 * statement. 442 */ 443 prev_evalskip = evalskip; 444 prev_skipcount = skipcount; 445 evalskip = 0; 446 447 last_trapsig = i; 448 savestatus = exitstatus; 449 setstackmark(&smark); 450 evalstring(stsavestr(trap[i]), 0); 451 popstackmark(&smark); 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 based on iflag. 482 */ 483 void 484 setinteractive(void) 485 { 486 setsignal(SIGINT); 487 setsignal(SIGQUIT); 488 setsignal(SIGTERM); 489 } 490 491 492 /* 493 * Called to exit the shell. 494 */ 495 void 496 exitshell(int status) 497 { 498 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 499 exiting = 1; 500 exiting_exitstatus = status; 501 exitshell_savedstatus(); 502 } 503 504 void 505 exitshell_savedstatus(void) 506 { 507 struct jmploc loc1, loc2; 508 char *p; 509 int sig = 0; 510 sigset_t sigs; 511 512 if (!exiting) { 513 if (in_dotrap && last_trapsig) { 514 sig = last_trapsig; 515 exiting_exitstatus = sig + 128; 516 } else 517 exiting_exitstatus = oexitstatus; 518 } 519 exitstatus = oexitstatus = exiting_exitstatus; 520 if (!setjmp(loc1.loc)) { 521 handler = &loc1; 522 if ((p = trap[0]) != NULL && *p != '\0') { 523 /* 524 * Reset evalskip, or the trap on EXIT could be 525 * interrupted if the last command was a "return". 526 */ 527 evalskip = 0; 528 trap[0] = NULL; 529 FORCEINTON; 530 evalstring(p, 0); 531 } 532 } 533 if (!setjmp(loc2.loc)) { 534 handler = &loc2; /* probably unnecessary */ 535 FORCEINTON; 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