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 1.32 2006/04/17 17:55:11 schweikh Exp $ 38 * $DragonFly: src/bin/sh/trap.c,v 1.5 2007/01/14 06:38:27 pavalos Exp $ 39 */ 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 * Set the signal handler for the specified signal. The routine figures 226 * out what it should be set to. 227 */ 228 void 229 setsignal(int signo) 230 { 231 int action; 232 sig_t sig, sigact = SIG_DFL; 233 char *t; 234 235 if ((t = trap[signo]) == NULL) 236 action = S_DFL; 237 else if (*t != '\0') 238 action = S_CATCH; 239 else 240 action = S_IGN; 241 if (action == S_DFL) { 242 switch (signo) { 243 case SIGINT: 244 action = S_CATCH; 245 break; 246 case SIGQUIT: 247 #ifdef DEBUG 248 { 249 extern int debug; 250 251 if (debug) 252 break; 253 } 254 #endif 255 action = S_CATCH; 256 break; 257 case SIGTERM: 258 if (rootshell && iflag) 259 action = S_IGN; 260 break; 261 #if JOBS 262 case SIGTSTP: 263 case SIGTTOU: 264 if (rootshell && mflag) 265 action = S_IGN; 266 break; 267 #endif 268 #ifndef NO_HISTORY 269 case SIGWINCH: 270 if (rootshell && iflag) 271 action = S_CATCH; 272 break; 273 #endif 274 } 275 } 276 277 t = &sigmode[signo]; 278 if (*t == 0) { 279 /* 280 * current setting unknown 281 */ 282 if (!getsigaction(signo, &sigact)) { 283 /* 284 * Pretend it worked; maybe we should give a warning 285 * here, but other shells don't. We don't alter 286 * sigmode, so that we retry every time. 287 */ 288 return; 289 } 290 if (sigact == SIG_IGN) { 291 if (mflag && (signo == SIGTSTP || 292 signo == SIGTTIN || signo == SIGTTOU)) { 293 *t = S_IGN; /* don't hard ignore these */ 294 } else 295 *t = S_HARD_IGN; 296 } else { 297 *t = S_RESET; /* force to be set */ 298 } 299 } 300 if (*t == S_HARD_IGN || *t == action) 301 return; 302 switch (action) { 303 case S_DFL: sigact = SIG_DFL; break; 304 case S_CATCH: sigact = onsig; break; 305 case S_IGN: sigact = SIG_IGN; break; 306 } 307 *t = action; 308 sig = signal(signo, sigact); 309 if (sig != SIG_ERR && action == S_CATCH) 310 siginterrupt(signo, 1); 311 } 312 313 314 /* 315 * Return the current setting for sig w/o changing it. 316 */ 317 static int 318 getsigaction(int signo, sig_t *sigact) 319 { 320 struct sigaction sa; 321 322 if (sigaction(signo, NULL, &sa) == -1) 323 return 0; 324 *sigact = (sig_t) sa.sa_handler; 325 return 1; 326 } 327 328 329 /* 330 * Ignore a signal. 331 */ 332 void 333 ignoresig(int signo) 334 { 335 336 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) { 337 signal(signo, SIG_IGN); 338 } 339 sigmode[signo] = S_HARD_IGN; 340 } 341 342 343 #ifdef mkinit 344 INCLUDE <signal.h> 345 INCLUDE "trap.h" 346 347 SHELLPROC { 348 char *sm; 349 350 clear_traps(); 351 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 352 if (*sm == S_IGN) 353 *sm = S_HARD_IGN; 354 } 355 } 356 #endif 357 358 359 /* 360 * Signal handler. 361 */ 362 void 363 onsig(int signo) 364 { 365 366 if (signo == SIGINT && trap[SIGINT] == NULL) { 367 onint(); 368 return; 369 } 370 371 if (signo != SIGCHLD || !ignore_sigchld) 372 gotsig[signo] = 1; 373 pendingsigs++; 374 375 /* If we are currently in a wait builtin, prepare to break it */ 376 if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0) 377 breakwaitcmd = 1; 378 /* 379 * If a trap is set, not ignored and not the null command, we need 380 * to make sure traps are executed even when a child blocks signals. 381 */ 382 if (Tflag && 383 trap[signo] != NULL && 384 ! (trap[signo][0] == '\0') && 385 ! (trap[signo][0] == ':' && trap[signo][1] == '\0')) 386 breakwaitcmd = 1; 387 388 #ifndef NO_HISTORY 389 if (signo == SIGWINCH) 390 gotwinch = 1; 391 #endif 392 } 393 394 395 /* 396 * Called to execute a trap. Perhaps we should avoid entering new trap 397 * handlers while we are executing a trap handler. 398 */ 399 void 400 dotrap(void) 401 { 402 int i; 403 int savestatus; 404 405 in_dotrap++; 406 for (;;) { 407 for (i = 1; i < NSIG; i++) { 408 if (gotsig[i]) { 409 gotsig[i] = 0; 410 if (trap[i]) { 411 /* 412 * Ignore SIGCHLD to avoid infinite 413 * recursion if the trap action does 414 * a fork. 415 */ 416 if (i == SIGCHLD) 417 ignore_sigchld++; 418 savestatus = exitstatus; 419 evalstring(trap[i]); 420 exitstatus = savestatus; 421 if (i == SIGCHLD) 422 ignore_sigchld--; 423 } 424 break; 425 } 426 } 427 if (i >= NSIG) 428 break; 429 } 430 in_dotrap--; 431 pendingsigs = 0; 432 } 433 434 435 /* 436 * Controls whether the shell is interactive or not. 437 */ 438 void 439 setinteractive(int on) 440 { 441 static int is_interactive = -1; 442 443 if (on == is_interactive) 444 return; 445 setsignal(SIGINT); 446 setsignal(SIGQUIT); 447 setsignal(SIGTERM); 448 #ifndef NO_HISTORY 449 setsignal(SIGWINCH); 450 #endif 451 is_interactive = on; 452 } 453 454 455 /* 456 * Called to exit the shell. 457 */ 458 void 459 exitshell(int status) 460 { 461 struct jmploc loc1, loc2; 462 char *p; 463 464 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 465 if (setjmp(loc1.loc)) { 466 goto l1; 467 } 468 if (setjmp(loc2.loc)) { 469 goto l2; 470 } 471 handler = &loc1; 472 if ((p = trap[0]) != NULL && *p != '\0') { 473 trap[0] = NULL; 474 evalstring(p); 475 } 476 l1: handler = &loc2; /* probably unnecessary */ 477 flushall(); 478 #if JOBS 479 setjobctl(0); 480 #endif 481 l2: _exit(status); 482 } 483