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