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 1.3 2003/10/14 23:03:08 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 static int 90 sigstring_to_signum(char *sig) 91 { 92 93 if (is_number(sig)) { 94 int signo; 95 96 signo = atoi(sig); 97 return ((signo >= 0 && signo < NSIG) ? signo : (-1)); 98 } else if (strcasecmp(sig, "exit") == 0) { 99 return (0); 100 } else { 101 int n; 102 103 if (strncasecmp(sig, "sig", 3) == 0) 104 sig += 3; 105 for (n = 1; n < sys_nsig; n++) { 106 if (sys_signame[n] && strcasecmp(sys_signame[n], sig) == 0) 107 return (n); 108 } 109 } 110 return (-1); 111 } 112 113 114 /* 115 * Print a list of valid signal names. 116 */ 117 static void 118 printsignals(void) 119 { 120 int n; 121 122 for (n = 1; n < sys_nsig; n++) { 123 out1fmt("%s", sys_signame[n]); 124 if (n == (NSIG / 2) || n == (NSIG - 1)) 125 out1str("\n"); 126 else 127 out1c(' '); 128 } 129 } 130 131 132 /* 133 * The trap builtin. 134 */ 135 int 136 trapcmd(int argc, char **argv) 137 { 138 char *action; 139 int signo; 140 141 if (argc <= 1) { 142 for (signo = 0 ; signo < sys_nsig; signo++) { 143 if (trap[signo] != NULL) { 144 out1fmt("trap -- '%s' %s\n", trap[signo], 145 (signo) ? sys_signame[signo] : "exit"); 146 } 147 } 148 return 0; 149 } 150 action = NULL; 151 if (*++argv && strcmp(*argv, "--") == 0) 152 argv++; 153 if (*argv && sigstring_to_signum(*argv) == -1) { 154 if ((*argv)[0] != '-') { 155 action = *argv; 156 argv++; 157 } else if ((*argv)[1] == '\0') { 158 argv++; 159 } else if ((*argv)[1] == 'l' && (*argv)[2] == '\0') { 160 printsignals(); 161 return 0; 162 } else { 163 error("bad option %s", *argv); 164 } 165 } 166 while (*argv) { 167 if ((signo = sigstring_to_signum(*argv)) == -1) 168 error("bad signal %s", *argv); 169 INTOFF; 170 if (action) 171 action = savestr(action); 172 if (trap[signo]) 173 ckfree(trap[signo]); 174 trap[signo] = action; 175 if (signo != 0) 176 setsignal(signo); 177 INTON; 178 argv++; 179 } 180 return 0; 181 } 182 183 184 /* 185 * Clear traps on a fork. 186 */ 187 void 188 clear_traps(void) 189 { 190 char *volatile *tp; 191 192 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 193 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 194 INTOFF; 195 ckfree(*tp); 196 *tp = NULL; 197 if (tp != &trap[0]) 198 setsignal(tp - trap); 199 INTON; 200 } 201 } 202 } 203 204 205 /* 206 * Set the signal handler for the specified signal. The routine figures 207 * out what it should be set to. 208 */ 209 void 210 setsignal(int signo) 211 { 212 int action; 213 sig_t sig, sigact = SIG_DFL; 214 char *t; 215 216 if ((t = trap[signo]) == NULL) 217 action = S_DFL; 218 else if (*t != '\0') 219 action = S_CATCH; 220 else 221 action = S_IGN; 222 if (action == S_DFL) { 223 switch (signo) { 224 case SIGINT: 225 action = S_CATCH; 226 break; 227 case SIGQUIT: 228 #ifdef DEBUG 229 { 230 extern int debug; 231 232 if (debug) 233 break; 234 } 235 #endif 236 action = S_CATCH; 237 break; 238 case SIGTERM: 239 if (rootshell && iflag) 240 action = S_IGN; 241 break; 242 #if JOBS 243 case SIGTSTP: 244 case SIGTTOU: 245 if (rootshell && mflag) 246 action = S_IGN; 247 break; 248 #endif 249 #ifndef NO_HISTORY 250 case SIGWINCH: 251 if (rootshell && iflag) 252 action = S_CATCH; 253 break; 254 #endif 255 } 256 } 257 258 t = &sigmode[signo]; 259 if (*t == 0) { 260 /* 261 * current setting unknown 262 */ 263 if (!getsigaction(signo, &sigact)) { 264 /* 265 * Pretend it worked; maybe we should give a warning 266 * here, but other shells don't. We don't alter 267 * sigmode, so that we retry every time. 268 */ 269 return; 270 } 271 if (sigact == SIG_IGN) { 272 if (mflag && (signo == SIGTSTP || 273 signo == SIGTTIN || signo == SIGTTOU)) { 274 *t = S_IGN; /* don't hard ignore these */ 275 } else 276 *t = S_HARD_IGN; 277 } else { 278 *t = S_RESET; /* force to be set */ 279 } 280 } 281 if (*t == S_HARD_IGN || *t == action) 282 return; 283 switch (action) { 284 case S_DFL: sigact = SIG_DFL; break; 285 case S_CATCH: sigact = onsig; break; 286 case S_IGN: sigact = SIG_IGN; break; 287 } 288 *t = action; 289 sig = signal(signo, sigact); 290 if (sig != SIG_ERR && action == S_CATCH) 291 siginterrupt(signo, 1); 292 } 293 294 295 /* 296 * Return the current setting for sig w/o changing it. 297 */ 298 static int 299 getsigaction(int signo, sig_t *sigact) 300 { 301 struct sigaction sa; 302 303 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 304 return 0; 305 *sigact = (sig_t) sa.sa_handler; 306 return 1; 307 } 308 309 310 /* 311 * Ignore a signal. 312 */ 313 void 314 ignoresig(int signo) 315 { 316 317 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) { 318 signal(signo, SIG_IGN); 319 } 320 sigmode[signo] = S_HARD_IGN; 321 } 322 323 324 #ifdef mkinit 325 INCLUDE <signal.h> 326 INCLUDE "trap.h" 327 328 SHELLPROC { 329 char *sm; 330 331 clear_traps(); 332 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 333 if (*sm == S_IGN) 334 *sm = S_HARD_IGN; 335 } 336 } 337 #endif 338 339 340 /* 341 * Signal handler. 342 */ 343 void 344 onsig(int signo) 345 { 346 347 if (signo == SIGINT && trap[SIGINT] == NULL) { 348 onint(); 349 return; 350 } 351 352 if (signo != SIGCHLD || !ignore_sigchld) 353 gotsig[signo] = 1; 354 pendingsigs++; 355 356 /* If we are currently in a wait builtin, prepare to break it */ 357 if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0) 358 breakwaitcmd = 1; 359 /* 360 * If a trap is set, not ignored and not the null command, we need 361 * to make sure traps are executed even when a child blocks signals. 362 */ 363 if (Tflag && 364 trap[signo] != NULL && 365 ! trap[signo][0] == '\0' && 366 ! (trap[signo][0] == ':' && trap[signo][1] == '\0')) 367 breakwaitcmd = 1; 368 369 #ifndef NO_HISTORY 370 if (signo == SIGWINCH) 371 gotwinch = 1; 372 #endif 373 } 374 375 376 /* 377 * Called to execute a trap. Perhaps we should avoid entering new trap 378 * handlers while we are executing a trap handler. 379 */ 380 void 381 dotrap(void) 382 { 383 int i; 384 int savestatus; 385 386 in_dotrap++; 387 for (;;) { 388 for (i = 1; i < NSIG; i++) { 389 if (gotsig[i]) { 390 gotsig[i] = 0; 391 if (trap[i]) { 392 /* 393 * Ignore SIGCHLD to avoid infinite recursion 394 * if the trap action does a fork. 395 */ 396 if (i == SIGCHLD) 397 ignore_sigchld++; 398 savestatus = exitstatus; 399 evalstring(trap[i]); 400 exitstatus = savestatus; 401 if (i == SIGCHLD) 402 ignore_sigchld--; 403 } 404 break; 405 } 406 } 407 if (i >= NSIG) 408 break; 409 } 410 in_dotrap--; 411 pendingsigs = 0; 412 } 413 414 415 /* 416 * Controls whether the shell is interactive or not. 417 */ 418 void 419 setinteractive(int on) 420 { 421 static int is_interactive = -1; 422 423 if (on == is_interactive) 424 return; 425 setsignal(SIGINT); 426 setsignal(SIGQUIT); 427 setsignal(SIGTERM); 428 #ifndef NO_HISTORY 429 setsignal(SIGWINCH); 430 #endif 431 is_interactive = on; 432 } 433 434 435 /* 436 * Called to exit the shell. 437 */ 438 void 439 exitshell(int status) 440 { 441 struct jmploc loc1, loc2; 442 char *p; 443 444 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 445 if (setjmp(loc1.loc)) { 446 goto l1; 447 } 448 if (setjmp(loc2.loc)) { 449 goto l2; 450 } 451 handler = &loc1; 452 if ((p = trap[0]) != NULL && *p != '\0') { 453 trap[0] = NULL; 454 evalstring(p); 455 } 456 l1: handler = &loc2; /* probably unnecessary */ 457 flushall(); 458 #if JOBS 459 setjobctl(0); 460 #endif 461 l2: _exit(status); 462 } 463