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