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 "myhistedit.h" 59 60 61 /* 62 * Sigmode records the current value of the signal handlers for the various 63 * modes. A value of zero means that the current handler is not known. 64 * S_HARD_IGN indicates that the signal was ignored on entry to the shell, 65 */ 66 67 #define S_DFL 1 /* default signal handling (SIG_DFL) */ 68 #define S_CATCH 2 /* signal is caught */ 69 #define S_IGN 3 /* signal is ignored (SIG_IGN) */ 70 #define S_HARD_IGN 4 /* signal is ignored permanently */ 71 #define S_RESET 5 /* temporary - to reset a hard ignored sig */ 72 73 74 MKINIT char sigmode[NSIG]; /* current value of signal */ 75 int pendingsigs; /* indicates some signal received */ 76 int in_dotrap; /* do we execute in a trap handler? */ 77 static char *volatile trap[NSIG]; /* trap handler commands */ 78 static volatile sig_atomic_t gotsig[NSIG]; 79 /* indicates specified signal received */ 80 static int ignore_sigchld; /* Used while handling SIGCHLD traps. */ 81 volatile sig_atomic_t gotwinch; 82 static int last_trapsig; 83 84 static int exiting; /* exitshell() has been called */ 85 static int exiting_exitstatus; /* value passed to exitshell() */ 86 87 static int getsigaction(int, sig_t *); 88 89 90 /* 91 * Map a string to a signal number. 92 * 93 * Note: the signal number may exceed NSIG. 94 */ 95 static int 96 sigstring_to_signum(char *sig) 97 { 98 99 if (is_number(sig)) { 100 int signo; 101 102 signo = atoi(sig); 103 return ((signo >= 0 && signo < NSIG) ? signo : (-1)); 104 } else if (strcasecmp(sig, "exit") == 0) { 105 return (0); 106 } else { 107 int n; 108 109 if (strncasecmp(sig, "sig", 3) == 0) 110 sig += 3; 111 for (n = 1; n < sys_nsig; n++) 112 if (sys_signame[n] && 113 strcasecmp(sys_signame[n], sig) == 0) 114 return (n); 115 } 116 return (-1); 117 } 118 119 120 /* 121 * Print a list of valid signal names. 122 */ 123 static void 124 printsignals(void) 125 { 126 int n, outlen; 127 128 outlen = 0; 129 for (n = 1; n < sys_nsig; n++) { 130 if (sys_signame[n]) { 131 out1fmt("%s", sys_signame[n]); 132 outlen += strlen(sys_signame[n]); 133 } else { 134 out1fmt("%d", n); 135 outlen += 3; /* good enough */ 136 } 137 ++outlen; 138 if (outlen > 71 || n == sys_nsig - 1) { 139 out1str("\n"); 140 outlen = 0; 141 } else { 142 out1c(' '); 143 } 144 } 145 } 146 147 148 /* 149 * The trap builtin. 150 */ 151 int 152 trapcmd(int argc, char **argv) 153 { 154 char *action; 155 int signo; 156 int errors = 0; 157 int i; 158 159 while ((i = nextopt("l")) != '\0') { 160 switch (i) { 161 case 'l': 162 printsignals(); 163 return (0); 164 } 165 } 166 argv = argptr; 167 168 if (*argv == NULL) { 169 for (signo = 0 ; signo < sys_nsig ; signo++) { 170 if (signo < NSIG && trap[signo] != NULL) { 171 out1str("trap -- "); 172 out1qstr(trap[signo]); 173 if (signo == 0) { 174 out1str(" exit\n"); 175 } else if (sys_signame[signo]) { 176 out1fmt(" %s\n", sys_signame[signo]); 177 } else { 178 out1fmt(" %d\n", signo); 179 } 180 } 181 } 182 return 0; 183 } 184 action = NULL; 185 if (*argv && sigstring_to_signum(*argv) == -1) { 186 if (strcmp(*argv, "-") == 0) 187 argv++; 188 else { 189 action = *argv; 190 argv++; 191 } 192 } 193 while (*argv) { 194 if ((signo = sigstring_to_signum(*argv)) == -1) { 195 warning("bad signal %s", *argv); 196 errors = 1; 197 } 198 INTOFF; 199 if (action) 200 action = savestr(action); 201 if (trap[signo]) 202 ckfree(trap[signo]); 203 trap[signo] = action; 204 if (signo != 0) 205 setsignal(signo); 206 INTON; 207 argv++; 208 } 209 return errors; 210 } 211 212 213 /* 214 * Clear traps on a fork. 215 */ 216 void 217 clear_traps(void) 218 { 219 char *volatile *tp; 220 221 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 222 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 223 INTOFF; 224 ckfree(*tp); 225 *tp = NULL; 226 if (tp != &trap[0]) 227 setsignal(tp - trap); 228 INTON; 229 } 230 } 231 } 232 233 234 /* 235 * Check if we have any traps enabled. 236 */ 237 int 238 have_traps(void) 239 { 240 char *volatile *tp; 241 242 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 243 if (*tp && **tp) /* trap not NULL or SIG_IGN */ 244 return 1; 245 } 246 return 0; 247 } 248 249 /* 250 * Set the signal handler for the specified signal. The routine figures 251 * out what it should be set to. 252 */ 253 void 254 setsignal(int signo) 255 { 256 int action; 257 sig_t sigact = SIG_DFL; 258 struct sigaction sa; 259 char *t; 260 261 if ((t = trap[signo]) == NULL) 262 action = S_DFL; 263 else if (*t != '\0') 264 action = S_CATCH; 265 else 266 action = S_IGN; 267 if (action == S_DFL) { 268 switch (signo) { 269 case SIGINT: 270 action = S_CATCH; 271 break; 272 case SIGQUIT: 273 #ifdef DEBUG 274 { 275 extern int debug; 276 277 if (debug) 278 break; 279 } 280 #endif 281 action = S_CATCH; 282 break; 283 case SIGTERM: 284 if (rootshell && iflag) 285 action = S_IGN; 286 break; 287 #if JOBS 288 case SIGTSTP: 289 case SIGTTOU: 290 if (rootshell && mflag) 291 action = S_IGN; 292 break; 293 #endif 294 #ifndef NO_HISTORY 295 case SIGWINCH: 296 if (rootshell && iflag) 297 action = S_CATCH; 298 break; 299 #endif 300 } 301 } 302 303 t = &sigmode[signo]; 304 if (*t == 0) { 305 /* 306 * current setting unknown 307 */ 308 if (!getsigaction(signo, &sigact)) { 309 /* 310 * Pretend it worked; maybe we should give a warning 311 * here, but other shells don't. We don't alter 312 * sigmode, so that we retry every time. 313 */ 314 return; 315 } 316 if (sigact == SIG_IGN) { 317 if (mflag && (signo == SIGTSTP || 318 signo == SIGTTIN || signo == SIGTTOU)) { 319 *t = S_IGN; /* don't hard ignore these */ 320 } else 321 *t = S_HARD_IGN; 322 } else { 323 *t = S_RESET; /* force to be set */ 324 } 325 } 326 if (*t == S_HARD_IGN || *t == action) 327 return; 328 switch (action) { 329 case S_DFL: sigact = SIG_DFL; break; 330 case S_CATCH: sigact = onsig; break; 331 case S_IGN: sigact = SIG_IGN; break; 332 } 333 *t = action; 334 sa.sa_handler = sigact; 335 sa.sa_flags = 0; 336 sigemptyset(&sa.sa_mask); 337 sigaction(signo, &sa, NULL); 338 } 339 340 341 /* 342 * Return the current setting for sig w/o changing it. 343 */ 344 static int 345 getsigaction(int signo, sig_t *sigact) 346 { 347 struct sigaction sa; 348 349 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 350 return 0; 351 *sigact = (sig_t) sa.sa_handler; 352 return 1; 353 } 354 355 356 /* 357 * Ignore a signal. 358 */ 359 void 360 ignoresig(int signo) 361 { 362 363 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) { 364 signal(signo, SIG_IGN); 365 } 366 sigmode[signo] = S_HARD_IGN; 367 } 368 369 370 #ifdef mkinit 371 INCLUDE <signal.h> 372 INCLUDE "trap.h" 373 374 SHELLPROC { 375 char *sm; 376 377 clear_traps(); 378 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 379 if (*sm == S_IGN) 380 *sm = S_HARD_IGN; 381 } 382 } 383 #endif 384 385 386 /* 387 * Signal handler. 388 */ 389 void 390 onsig(int signo) 391 { 392 393 if (signo == SIGINT && trap[SIGINT] == NULL) { 394 onint(); 395 return; 396 } 397 398 if (signo != SIGCHLD || !ignore_sigchld) 399 gotsig[signo] = 1; 400 pendingsigs++; 401 402 /* If we are currently in a wait builtin, prepare to break it */ 403 if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0) 404 breakwaitcmd = 1; 405 /* 406 * If a trap is set, not ignored and not the null command, we need 407 * to make sure traps are executed even when a child blocks signals. 408 */ 409 if (Tflag && 410 trap[signo] != NULL && 411 ! (trap[signo][0] == '\0') && 412 ! (trap[signo][0] == ':' && trap[signo][1] == '\0')) 413 breakwaitcmd = 1; 414 415 #ifndef NO_HISTORY 416 if (signo == SIGWINCH) 417 gotwinch = 1; 418 #endif 419 } 420 421 422 /* 423 * Called to execute a trap. Perhaps we should avoid entering new trap 424 * handlers while we are executing a trap handler. 425 */ 426 void 427 dotrap(void) 428 { 429 int i; 430 int savestatus; 431 432 in_dotrap++; 433 for (;;) { 434 for (i = 1; i < NSIG; i++) { 435 if (gotsig[i]) { 436 gotsig[i] = 0; 437 if (trap[i]) { 438 /* 439 * Ignore SIGCHLD to avoid infinite 440 * recursion if the trap action does 441 * a fork. 442 */ 443 if (i == SIGCHLD) 444 ignore_sigchld++; 445 last_trapsig = i; 446 savestatus = exitstatus; 447 evalstring(trap[i], 0); 448 exitstatus = savestatus; 449 if (i == SIGCHLD) 450 ignore_sigchld--; 451 } 452 break; 453 } 454 } 455 if (i >= NSIG) 456 break; 457 } 458 in_dotrap--; 459 pendingsigs = 0; 460 } 461 462 463 /* 464 * Controls whether the shell is interactive or not. 465 */ 466 void 467 setinteractive(int on) 468 { 469 static int is_interactive = -1; 470 471 if (on == is_interactive) 472 return; 473 setsignal(SIGINT); 474 setsignal(SIGQUIT); 475 setsignal(SIGTERM); 476 #ifndef NO_HISTORY 477 setsignal(SIGWINCH); 478 #endif 479 is_interactive = on; 480 } 481 482 483 /* 484 * Called to exit the shell. 485 */ 486 void 487 exitshell(int status) 488 { 489 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 490 exiting = 1; 491 exiting_exitstatus = status; 492 exitshell_savedstatus(); 493 } 494 495 void 496 exitshell_savedstatus(void) 497 { 498 struct jmploc loc1, loc2; 499 char *p; 500 int sig = 0; 501 sigset_t sigs; 502 503 if (!exiting) { 504 if (in_dotrap && last_trapsig) { 505 sig = last_trapsig; 506 exiting_exitstatus = sig + 128; 507 } else 508 exiting_exitstatus = oexitstatus; 509 } 510 exitstatus = oexitstatus = exiting_exitstatus; 511 if (setjmp(loc1.loc)) { 512 goto l1; 513 } 514 if (setjmp(loc2.loc)) { 515 goto l2; 516 } 517 handler = &loc1; 518 if ((p = trap[0]) != NULL && *p != '\0') { 519 trap[0] = NULL; 520 evalstring(p, 0); 521 } 522 l1: handler = &loc2; /* probably unnecessary */ 523 flushall(); 524 #if JOBS 525 setjobctl(0); 526 #endif 527 l2: 528 if (sig != 0 && sig != SIGSTOP && sig != SIGTSTP && sig != SIGTTIN && 529 sig != SIGTTOU) { 530 signal(sig, SIG_DFL); 531 sigemptyset(&sigs); 532 sigaddset(&sigs, sig); 533 sigprocmask(SIG_UNBLOCK, &sigs, NULL); 534 kill(getpid(), sig); 535 /* If the default action is to ignore, fall back to _exit(). */ 536 } 537 _exit(exiting_exitstatus); 538 } 539