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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)trap.c 8.5 (Berkeley) 6/5/95 37 * $FreeBSD: src/bin/sh/trap.c,v 1.45 2011/02/04 22:47:55 jilles Exp $ 38 */ 39 40 #include <signal.h> 41 #include <unistd.h> 42 #include <stdlib.h> 43 44 #include "shell.h" 45 #include "main.h" 46 #include "nodes.h" /* for other headers */ 47 #include "eval.h" 48 #include "jobs.h" 49 #include "show.h" 50 #include "options.h" 51 #include "syntax.h" 52 #include "output.h" 53 #include "memalloc.h" 54 #include "error.h" 55 #include "trap.h" 56 #include "mystring.h" 57 #include "myhistedit.h" 58 59 60 /* 61 * Sigmode records the current value of the signal handlers for the various 62 * modes. A value of zero means that the current handler is not known. 63 * S_HARD_IGN indicates that the signal was ignored on entry to the shell, 64 */ 65 66 #define S_DFL 1 /* default signal handling (SIG_DFL) */ 67 #define S_CATCH 2 /* signal is caught */ 68 #define S_IGN 3 /* signal is ignored (SIG_IGN) */ 69 #define S_HARD_IGN 4 /* signal is ignored permanently */ 70 #define S_RESET 5 /* temporary - to reset a hard ignored sig */ 71 72 73 MKINIT char sigmode[NSIG]; /* current value of signal */ 74 int pendingsigs; /* indicates some signal received */ 75 int in_dotrap; /* do we execute in a trap handler? */ 76 static char *volatile trap[NSIG]; /* trap handler commands */ 77 static volatile sig_atomic_t gotsig[NSIG]; 78 /* indicates specified signal received */ 79 static int ignore_sigchld; /* Used while handling SIGCHLD traps. */ 80 volatile sig_atomic_t gotwinch; 81 static int last_trapsig; 82 83 static int exiting; /* exitshell() has been called */ 84 static int exiting_exitstatus; /* value passed to exitshell() */ 85 86 static int getsigaction(int, sig_t *); 87 88 89 /* 90 * Map a string to a signal number. 91 * 92 * Note: the signal number may exceed NSIG. 93 */ 94 static int 95 sigstring_to_signum(char *sig) 96 { 97 98 if (is_number(sig)) { 99 int signo; 100 101 signo = atoi(sig); 102 return ((signo >= 0 && signo < NSIG) ? signo : (-1)); 103 } else if (strcasecmp(sig, "EXIT") == 0) { 104 return (0); 105 } else { 106 int n; 107 108 if (strncasecmp(sig, "SIG", 3) == 0) 109 sig += 3; 110 for (n = 1; n < sys_nsig; n++) 111 if (sys_signame[n] && 112 strcasecmp(sys_signame[n], sig) == 0) 113 return (n); 114 } 115 return (-1); 116 } 117 118 119 /* 120 * Print a list of valid signal names. 121 */ 122 static void 123 printsignals(void) 124 { 125 int n, outlen; 126 127 outlen = 0; 128 for (n = 1; n < sys_nsig; n++) { 129 if (sys_signame[n]) { 130 out1fmt("%s", sys_signame[n]); 131 outlen += strlen(sys_signame[n]); 132 } else { 133 out1fmt("%d", n); 134 outlen += 3; /* good enough */ 135 } 136 ++outlen; 137 if (outlen > 71 || n == sys_nsig - 1) { 138 out1str("\n"); 139 outlen = 0; 140 } else { 141 out1c(' '); 142 } 143 } 144 } 145 146 147 /* 148 * The trap builtin. 149 */ 150 int 151 trapcmd(int argc __unused, char **argv) 152 { 153 char *action; 154 int signo; 155 int errors = 0; 156 int i; 157 158 while ((i = nextopt("l")) != '\0') { 159 switch (i) { 160 case 'l': 161 printsignals(); 162 return (0); 163 } 164 } 165 argv = argptr; 166 167 if (*argv == NULL) { 168 for (signo = 0 ; signo < sys_nsig ; signo++) { 169 if (signo < NSIG && trap[signo] != NULL) { 170 out1str("trap -- "); 171 out1qstr(trap[signo]); 172 if (signo == 0) { 173 out1str(" EXIT\n"); 174 } else if (sys_signame[signo]) { 175 out1fmt(" %s\n", sys_signame[signo]); 176 } else { 177 out1fmt(" %d\n", signo); 178 } 179 } 180 } 181 return 0; 182 } 183 action = NULL; 184 if (*argv && sigstring_to_signum(*argv) == -1) { 185 if (strcmp(*argv, "-") == 0) 186 argv++; 187 else { 188 action = *argv; 189 argv++; 190 } 191 } 192 while (*argv) { 193 if ((signo = sigstring_to_signum(*argv)) == -1) { 194 warning("bad signal %s", *argv); 195 errors = 1; 196 } 197 INTOFF; 198 if (action) 199 action = savestr(action); 200 if (trap[signo]) 201 ckfree(trap[signo]); 202 trap[signo] = action; 203 if (signo != 0) 204 setsignal(signo); 205 INTON; 206 argv++; 207 } 208 return errors; 209 } 210 211 212 /* 213 * Clear traps on a fork. 214 */ 215 void 216 clear_traps(void) 217 { 218 char *volatile *tp; 219 220 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 221 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 222 INTOFF; 223 ckfree(*tp); 224 *tp = NULL; 225 if (tp != &trap[0]) 226 setsignal(tp - trap); 227 INTON; 228 } 229 } 230 } 231 232 233 /* 234 * Check if we have any traps enabled. 235 */ 236 int 237 have_traps(void) 238 { 239 char *volatile *tp; 240 241 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 242 if (*tp && **tp) /* trap not NULL or SIG_IGN */ 243 return 1; 244 } 245 return 0; 246 } 247 248 /* 249 * Set the signal handler for the specified signal. The routine figures 250 * out what it should be set to. 251 */ 252 void 253 setsignal(int signo) 254 { 255 int action; 256 sig_t sigact = SIG_DFL; 257 struct sigaction sa; 258 char *t; 259 260 if ((t = trap[signo]) == NULL) 261 action = S_DFL; 262 else if (*t != '\0') 263 action = S_CATCH; 264 else 265 action = S_IGN; 266 if (action == S_DFL) { 267 switch (signo) { 268 case SIGINT: 269 action = S_CATCH; 270 break; 271 case SIGQUIT: 272 #ifdef DEBUG 273 { 274 extern int debug; 275 276 if (debug) 277 break; 278 } 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 #ifndef NO_HISTORY 294 case SIGWINCH: 295 if (rootshell && iflag) 296 action = S_CATCH; 297 break; 298 #endif 299 } 300 } 301 302 t = &sigmode[signo]; 303 if (*t == 0) { 304 /* 305 * current setting unknown 306 */ 307 if (!getsigaction(signo, &sigact)) { 308 /* 309 * Pretend it worked; maybe we should give a warning 310 * here, but other shells don't. We don't alter 311 * sigmode, so that we retry every time. 312 */ 313 return; 314 } 315 if (sigact == SIG_IGN) { 316 if (mflag && (signo == SIGTSTP || 317 signo == SIGTTIN || signo == SIGTTOU)) { 318 *t = S_IGN; /* don't hard ignore these */ 319 } else 320 *t = S_HARD_IGN; 321 } else { 322 *t = S_RESET; /* force to be set */ 323 } 324 } 325 if (*t == S_HARD_IGN || *t == action) 326 return; 327 switch (action) { 328 case S_DFL: sigact = SIG_DFL; break; 329 case S_CATCH: sigact = onsig; break; 330 case S_IGN: sigact = SIG_IGN; break; 331 } 332 *t = action; 333 sa.sa_handler = sigact; 334 sa.sa_flags = 0; 335 sigemptyset(&sa.sa_mask); 336 sigaction(signo, &sa, NULL); 337 } 338 339 340 /* 341 * Return the current setting for sig w/o changing it. 342 */ 343 static int 344 getsigaction(int signo, sig_t *sigact) 345 { 346 struct sigaction sa; 347 348 if (sigaction(signo, NULL, &sa) == -1) 349 return 0; 350 *sigact = (sig_t) sa.sa_handler; 351 return 1; 352 } 353 354 355 /* 356 * Ignore a signal. 357 */ 358 void 359 ignoresig(int signo) 360 { 361 362 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) { 363 signal(signo, SIG_IGN); 364 } 365 sigmode[signo] = S_HARD_IGN; 366 } 367 368 369 /* 370 * Signal handler. 371 */ 372 void 373 onsig(int signo) 374 { 375 376 if (signo == SIGINT && trap[SIGINT] == NULL) { 377 onint(); 378 return; 379 } 380 381 if (signo != SIGCHLD || !ignore_sigchld) 382 gotsig[signo] = 1; 383 pendingsigs++; 384 385 /* If we are currently in a wait builtin, prepare to break it */ 386 if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0) 387 breakwaitcmd = 1; 388 /* 389 * If a trap is set, not ignored and not the null command, we need 390 * to make sure traps are executed even when a child blocks signals. 391 */ 392 if (Tflag && 393 trap[signo] != NULL && 394 ! (trap[signo][0] == '\0') && 395 ! (trap[signo][0] == ':' && trap[signo][1] == '\0')) 396 breakwaitcmd = 1; 397 398 #ifndef NO_HISTORY 399 if (signo == SIGWINCH) 400 gotwinch = 1; 401 #endif 402 } 403 404 405 /* 406 * Called to execute a trap. Perhaps we should avoid entering new trap 407 * handlers while we are executing a trap handler. 408 */ 409 void 410 dotrap(void) 411 { 412 int i; 413 int savestatus; 414 415 in_dotrap++; 416 for (;;) { 417 for (i = 1; i < NSIG; i++) { 418 if (gotsig[i]) { 419 gotsig[i] = 0; 420 if (trap[i]) { 421 /* 422 * Ignore SIGCHLD to avoid infinite 423 * recursion if the trap action does 424 * a fork. 425 */ 426 if (i == SIGCHLD) 427 ignore_sigchld++; 428 last_trapsig = i; 429 savestatus = exitstatus; 430 evalstring(trap[i], 0); 431 exitstatus = savestatus; 432 if (i == SIGCHLD) 433 ignore_sigchld--; 434 } 435 break; 436 } 437 } 438 if (i >= NSIG) 439 break; 440 } 441 in_dotrap--; 442 pendingsigs = 0; 443 } 444 445 446 /* 447 * Controls whether the shell is interactive or not. 448 */ 449 void 450 setinteractive(int on) 451 { 452 static int is_interactive = -1; 453 454 if (on == is_interactive) 455 return; 456 setsignal(SIGINT); 457 setsignal(SIGQUIT); 458 setsignal(SIGTERM); 459 #ifndef NO_HISTORY 460 setsignal(SIGWINCH); 461 #endif 462 is_interactive = on; 463 } 464 465 466 /* 467 * Called to exit the shell. 468 */ 469 void 470 exitshell(int status) 471 { 472 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 473 exiting = 1; 474 exiting_exitstatus = status; 475 exitshell_savedstatus(); 476 } 477 478 void 479 exitshell_savedstatus(void) 480 { 481 struct jmploc loc1, loc2; 482 char *p; 483 volatile int sig = 0; 484 sigset_t sigs; 485 486 if (!exiting) { 487 if (in_dotrap && last_trapsig) { 488 sig = last_trapsig; 489 exiting_exitstatus = sig + 128; 490 } else 491 exiting_exitstatus = oexitstatus; 492 } 493 exitstatus = oexitstatus = exiting_exitstatus; 494 if (setjmp(loc1.loc)) { 495 goto l1; 496 } 497 if (setjmp(loc2.loc)) { 498 goto l2; 499 } 500 handler = &loc1; 501 if ((p = trap[0]) != NULL && *p != '\0') { 502 trap[0] = NULL; 503 evalstring(p, 0); 504 } 505 l1: handler = &loc2; /* probably unnecessary */ 506 flushall(); 507 #if JOBS 508 setjobctl(0); 509 #endif 510 l2: 511 if (sig != 0 && sig != SIGSTOP && sig != SIGTSTP && sig != SIGTTIN && 512 sig != SIGTTOU) { 513 signal(sig, SIG_DFL); 514 sigemptyset(&sigs); 515 sigaddset(&sigs, sig); 516 sigprocmask(SIG_UNBLOCK, &sigs, NULL); 517 kill(getpid(), sig); 518 /* If the default action is to ignore, fall back to _exit(). */ 519 } 520 _exit(exiting_exitstatus); 521 } 522