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 1.20.2.2 2002/08/27 01:36:28 tjr Exp $ 38 * $DragonFly: src/bin/sh/trap.c,v 1.4 2004/01/30 18:21:18 dillon 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] && strcasecmp(sys_signame[n], sig) == 0) 109 return (n); 110 } 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; 123 int outlen = 0; 124 125 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 if (signo == 0) { 157 out1fmt("trap -- '%s' %s\n", 158 trap[signo], "exit"); 159 } else if (sys_signame[signo]) { 160 out1fmt("trap -- '%s' %s\n", 161 trap[signo], 162 sys_signame[signo]); 163 } else { 164 out1fmt("trap -- '%s' %d\n", 165 trap[signo], signo); 166 } 167 } 168 } 169 return 0; 170 } 171 action = NULL; 172 if (*++argv && strcmp(*argv, "--") == 0) 173 argv++; 174 if (*argv && sigstring_to_signum(*argv) == -1) { 175 if ((*argv)[0] != '-') { 176 action = *argv; 177 argv++; 178 } else if ((*argv)[1] == '\0') { 179 argv++; 180 } else if ((*argv)[1] == 'l' && (*argv)[2] == '\0') { 181 printsignals(); 182 return 0; 183 } else { 184 error("bad option %s", *argv); 185 } 186 } 187 while (*argv) { 188 if ((signo = sigstring_to_signum(*argv)) == -1) 189 error("bad signal %s", *argv); 190 INTOFF; 191 if (action) 192 action = savestr(action); 193 if (trap[signo]) 194 ckfree(trap[signo]); 195 trap[signo] = action; 196 if (signo != 0) 197 setsignal(signo); 198 INTON; 199 argv++; 200 } 201 return 0; 202 } 203 204 205 /* 206 * Clear traps on a fork. 207 */ 208 void 209 clear_traps(void) 210 { 211 char *volatile *tp; 212 213 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 214 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 215 INTOFF; 216 ckfree(*tp); 217 *tp = NULL; 218 if (tp != &trap[0]) 219 setsignal(tp - trap); 220 INTON; 221 } 222 } 223 } 224 225 226 /* 227 * Set the signal handler for the specified signal. The routine figures 228 * out what it should be set to. 229 */ 230 void 231 setsignal(int signo) 232 { 233 int action; 234 sig_t sig, sigact = SIG_DFL; 235 char *t; 236 237 if ((t = trap[signo]) == NULL) 238 action = S_DFL; 239 else if (*t != '\0') 240 action = S_CATCH; 241 else 242 action = S_IGN; 243 if (action == S_DFL) { 244 switch (signo) { 245 case SIGINT: 246 action = S_CATCH; 247 break; 248 case SIGQUIT: 249 #ifdef DEBUG 250 { 251 extern int debug; 252 253 if (debug) 254 break; 255 } 256 #endif 257 action = S_CATCH; 258 break; 259 case SIGTERM: 260 if (rootshell && iflag) 261 action = S_IGN; 262 break; 263 #if JOBS 264 case SIGTSTP: 265 case SIGTTOU: 266 if (rootshell && mflag) 267 action = S_IGN; 268 break; 269 #endif 270 #ifndef NO_HISTORY 271 case SIGWINCH: 272 if (rootshell && iflag) 273 action = S_CATCH; 274 break; 275 #endif 276 } 277 } 278 279 t = &sigmode[signo]; 280 if (*t == 0) { 281 /* 282 * current setting unknown 283 */ 284 if (!getsigaction(signo, &sigact)) { 285 /* 286 * Pretend it worked; maybe we should give a warning 287 * here, but other shells don't. We don't alter 288 * sigmode, so that we retry every time. 289 */ 290 return; 291 } 292 if (sigact == SIG_IGN) { 293 if (mflag && (signo == SIGTSTP || 294 signo == SIGTTIN || signo == SIGTTOU)) { 295 *t = S_IGN; /* don't hard ignore these */ 296 } else 297 *t = S_HARD_IGN; 298 } else { 299 *t = S_RESET; /* force to be set */ 300 } 301 } 302 if (*t == S_HARD_IGN || *t == action) 303 return; 304 switch (action) { 305 case S_DFL: sigact = SIG_DFL; break; 306 case S_CATCH: sigact = onsig; break; 307 case S_IGN: sigact = SIG_IGN; break; 308 } 309 *t = action; 310 sig = signal(signo, sigact); 311 if (sig != SIG_ERR && action == S_CATCH) 312 siginterrupt(signo, 1); 313 } 314 315 316 /* 317 * Return the current setting for sig w/o changing it. 318 */ 319 static int 320 getsigaction(int signo, sig_t *sigact) 321 { 322 struct sigaction sa; 323 324 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 325 return 0; 326 *sigact = (sig_t) sa.sa_handler; 327 return 1; 328 } 329 330 331 /* 332 * Ignore a signal. 333 */ 334 void 335 ignoresig(int signo) 336 { 337 338 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) { 339 signal(signo, SIG_IGN); 340 } 341 sigmode[signo] = S_HARD_IGN; 342 } 343 344 345 #ifdef mkinit 346 INCLUDE <signal.h> 347 INCLUDE "trap.h" 348 349 SHELLPROC { 350 char *sm; 351 352 clear_traps(); 353 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 354 if (*sm == S_IGN) 355 *sm = S_HARD_IGN; 356 } 357 } 358 #endif 359 360 361 /* 362 * Signal handler. 363 */ 364 void 365 onsig(int signo) 366 { 367 368 if (signo == SIGINT && trap[SIGINT] == NULL) { 369 onint(); 370 return; 371 } 372 373 if (signo != SIGCHLD || !ignore_sigchld) 374 gotsig[signo] = 1; 375 pendingsigs++; 376 377 /* If we are currently in a wait builtin, prepare to break it */ 378 if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0) 379 breakwaitcmd = 1; 380 /* 381 * If a trap is set, not ignored and not the null command, we need 382 * to make sure traps are executed even when a child blocks signals. 383 */ 384 if (Tflag && 385 trap[signo] != NULL && 386 ! trap[signo][0] == '\0' && 387 ! (trap[signo][0] == ':' && trap[signo][1] == '\0')) 388 breakwaitcmd = 1; 389 390 #ifndef NO_HISTORY 391 if (signo == SIGWINCH) 392 gotwinch = 1; 393 #endif 394 } 395 396 397 /* 398 * Called to execute a trap. Perhaps we should avoid entering new trap 399 * handlers while we are executing a trap handler. 400 */ 401 void 402 dotrap(void) 403 { 404 int i; 405 int savestatus; 406 407 in_dotrap++; 408 for (;;) { 409 for (i = 1; i < NSIG; i++) { 410 if (gotsig[i]) { 411 gotsig[i] = 0; 412 if (trap[i]) { 413 /* 414 * Ignore SIGCHLD to avoid infinite recursion 415 * if the trap action does a fork. 416 */ 417 if (i == SIGCHLD) 418 ignore_sigchld++; 419 savestatus = exitstatus; 420 evalstring(trap[i]); 421 exitstatus = savestatus; 422 if (i == SIGCHLD) 423 ignore_sigchld--; 424 } 425 break; 426 } 427 } 428 if (i >= NSIG) 429 break; 430 } 431 in_dotrap--; 432 pendingsigs = 0; 433 } 434 435 436 /* 437 * Controls whether the shell is interactive or not. 438 */ 439 void 440 setinteractive(int on) 441 { 442 static int is_interactive = -1; 443 444 if (on == is_interactive) 445 return; 446 setsignal(SIGINT); 447 setsignal(SIGQUIT); 448 setsignal(SIGTERM); 449 #ifndef NO_HISTORY 450 setsignal(SIGWINCH); 451 #endif 452 is_interactive = on; 453 } 454 455 456 /* 457 * Called to exit the shell. 458 */ 459 void 460 exitshell(int status) 461 { 462 struct jmploc loc1, loc2; 463 char *p; 464 465 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 466 if (setjmp(loc1.loc)) { 467 goto l1; 468 } 469 if (setjmp(loc2.loc)) { 470 goto l2; 471 } 472 handler = &loc1; 473 if ((p = trap[0]) != NULL && *p != '\0') { 474 trap[0] = NULL; 475 evalstring(p); 476 } 477 l1: handler = &loc2; /* probably unnecessary */ 478 flushall(); 479 #if JOBS 480 setjobctl(0); 481 #endif 482 l2: _exit(status); 483 } 484