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 37 #ifndef lint 38 #if 0 39 static char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95"; 40 #endif 41 #endif /* not lint */ 42 #include <sys/cdefs.h> 43 __FBSDID("$FreeBSD: src/bin/sh/trap.c,v 1.20.2.2 2002/08/27 01:36:28 tjr Exp $"); 44 45 #include <signal.h> 46 #include <unistd.h> 47 #include <stdlib.h> 48 49 #include "shell.h" 50 #include "main.h" 51 #include "nodes.h" /* for other headers */ 52 #include "eval.h" 53 #include "jobs.h" 54 #include "show.h" 55 #include "options.h" 56 #include "syntax.h" 57 #include "output.h" 58 #include "memalloc.h" 59 #include "error.h" 60 #include "trap.h" 61 #include "mystring.h" 62 #include "myhistedit.h" 63 64 65 /* 66 * Sigmode records the current value of the signal handlers for the various 67 * modes. A value of zero means that the current handler is not known. 68 * S_HARD_IGN indicates that the signal was ignored on entry to the shell, 69 */ 70 71 #define S_DFL 1 /* default signal handling (SIG_DFL) */ 72 #define S_CATCH 2 /* signal is caught */ 73 #define S_IGN 3 /* signal is ignored (SIG_IGN) */ 74 #define S_HARD_IGN 4 /* signal is ignored permanently */ 75 #define S_RESET 5 /* temporary - to reset a hard ignored sig */ 76 77 78 MKINIT char sigmode[NSIG]; /* current value of signal */ 79 int pendingsigs; /* indicates some signal received */ 80 int in_dotrap; /* do we execute in a trap handler? */ 81 static char *volatile trap[NSIG]; /* trap handler commands */ 82 static volatile sig_atomic_t gotsig[NSIG]; 83 /* indicates specified signal received */ 84 static int ignore_sigchld; /* Used while handling SIGCHLD traps. */ 85 volatile sig_atomic_t gotwinch; 86 87 static int getsigaction(int, sig_t *); 88 89 90 /* 91 * Map a string to a signal number. 92 */ 93 static int 94 sigstring_to_signum(char *sig) 95 { 96 97 if (is_number(sig)) { 98 int signo; 99 100 signo = atoi(sig); 101 return ((signo >= 0 && signo < NSIG) ? signo : (-1)); 102 } else if (strcasecmp(sig, "exit") == 0) { 103 return (0); 104 } else { 105 int n; 106 107 if (strncasecmp(sig, "sig", 3) == 0) 108 sig += 3; 109 for (n = 1; n < NSIG; n++) 110 if (strcasecmp(sys_signame[n], sig) == 0) 111 return (n); 112 } 113 return (-1); 114 } 115 116 117 /* 118 * Print a list of valid signal names. 119 */ 120 static void 121 printsignals(void) 122 { 123 int n; 124 125 for (n = 1; n < NSIG; n++) { 126 out1fmt("%s", sys_signame[n]); 127 if (n == (NSIG / 2) || n == (NSIG - 1)) 128 out1str("\n"); 129 else 130 out1c(' '); 131 } 132 } 133 134 135 /* 136 * The trap builtin. 137 */ 138 int 139 trapcmd(int argc, char **argv) 140 { 141 char *action; 142 int signo; 143 144 if (argc <= 1) { 145 for (signo = 0 ; signo < NSIG ; signo++) { 146 if (trap[signo] != NULL) 147 out1fmt("trap -- '%s' %s\n", trap[signo], 148 (signo) ? sys_signame[signo] : "exit"); 149 } 150 return 0; 151 } 152 action = NULL; 153 if (*++argv && strcmp(*argv, "--") == 0) 154 argv++; 155 if (*argv && sigstring_to_signum(*argv) == -1) { 156 if ((*argv)[0] != '-') { 157 action = *argv; 158 argv++; 159 } else if ((*argv)[1] == '\0') { 160 argv++; 161 } else if ((*argv)[1] == 'l' && (*argv)[2] == '\0') { 162 printsignals(); 163 return 0; 164 } else { 165 error("bad option %s", *argv); 166 } 167 } 168 while (*argv) { 169 if ((signo = sigstring_to_signum(*argv)) == -1) 170 error("bad signal %s", *argv); 171 INTOFF; 172 if (action) 173 action = savestr(action); 174 if (trap[signo]) 175 ckfree(trap[signo]); 176 trap[signo] = action; 177 if (signo != 0) 178 setsignal(signo); 179 INTON; 180 argv++; 181 } 182 return 0; 183 } 184 185 186 /* 187 * Clear traps on a fork. 188 */ 189 void 190 clear_traps(void) 191 { 192 char *volatile *tp; 193 194 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 195 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 196 INTOFF; 197 ckfree(*tp); 198 *tp = NULL; 199 if (tp != &trap[0]) 200 setsignal(tp - trap); 201 INTON; 202 } 203 } 204 } 205 206 207 /* 208 * Set the signal handler for the specified signal. The routine figures 209 * out what it should be set to. 210 */ 211 void 212 setsignal(int signo) 213 { 214 int action; 215 sig_t sig, sigact = SIG_DFL; 216 char *t; 217 218 if ((t = trap[signo]) == NULL) 219 action = S_DFL; 220 else if (*t != '\0') 221 action = S_CATCH; 222 else 223 action = S_IGN; 224 if (action == S_DFL) { 225 switch (signo) { 226 case SIGINT: 227 action = S_CATCH; 228 break; 229 case SIGQUIT: 230 #ifdef DEBUG 231 { 232 extern int debug; 233 234 if (debug) 235 break; 236 } 237 #endif 238 action = S_CATCH; 239 break; 240 case SIGTERM: 241 if (rootshell && iflag) 242 action = S_IGN; 243 break; 244 #if JOBS 245 case SIGTSTP: 246 case SIGTTOU: 247 if (rootshell && mflag) 248 action = S_IGN; 249 break; 250 #endif 251 #ifndef NO_HISTORY 252 case SIGWINCH: 253 if (rootshell && iflag) 254 action = S_CATCH; 255 break; 256 #endif 257 } 258 } 259 260 t = &sigmode[signo]; 261 if (*t == 0) { 262 /* 263 * current setting unknown 264 */ 265 if (!getsigaction(signo, &sigact)) { 266 /* 267 * Pretend it worked; maybe we should give a warning 268 * here, but other shells don't. We don't alter 269 * sigmode, so that we retry every time. 270 */ 271 return; 272 } 273 if (sigact == SIG_IGN) { 274 if (mflag && (signo == SIGTSTP || 275 signo == SIGTTIN || signo == SIGTTOU)) { 276 *t = S_IGN; /* don't hard ignore these */ 277 } else 278 *t = S_HARD_IGN; 279 } else { 280 *t = S_RESET; /* force to be set */ 281 } 282 } 283 if (*t == S_HARD_IGN || *t == action) 284 return; 285 switch (action) { 286 case S_DFL: sigact = SIG_DFL; break; 287 case S_CATCH: sigact = onsig; break; 288 case S_IGN: sigact = SIG_IGN; break; 289 } 290 *t = action; 291 sig = signal(signo, sigact); 292 if (sig != SIG_ERR && action == S_CATCH) 293 siginterrupt(signo, 1); 294 } 295 296 297 /* 298 * Return the current setting for sig w/o changing it. 299 */ 300 static int 301 getsigaction(int signo, sig_t *sigact) 302 { 303 struct sigaction sa; 304 305 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 306 return 0; 307 *sigact = (sig_t) sa.sa_handler; 308 return 1; 309 } 310 311 312 /* 313 * Ignore a signal. 314 */ 315 void 316 ignoresig(int signo) 317 { 318 319 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) { 320 signal(signo, SIG_IGN); 321 } 322 sigmode[signo] = S_HARD_IGN; 323 } 324 325 326 #ifdef mkinit 327 INCLUDE <signal.h> 328 INCLUDE "trap.h" 329 330 SHELLPROC { 331 char *sm; 332 333 clear_traps(); 334 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 335 if (*sm == S_IGN) 336 *sm = S_HARD_IGN; 337 } 338 } 339 #endif 340 341 342 /* 343 * Signal handler. 344 */ 345 void 346 onsig(int signo) 347 { 348 349 if (signo == SIGINT && trap[SIGINT] == NULL) { 350 onint(); 351 return; 352 } 353 354 if (signo != SIGCHLD || !ignore_sigchld) 355 gotsig[signo] = 1; 356 pendingsigs++; 357 358 /* If we are currently in a wait builtin, prepare to break it */ 359 if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0) 360 breakwaitcmd = 1; 361 /* 362 * If a trap is set, not ignored and not the null command, we need 363 * to make sure traps are executed even when a child blocks signals. 364 */ 365 if (Tflag && 366 trap[signo] != NULL && 367 ! trap[signo][0] == '\0' && 368 ! (trap[signo][0] == ':' && trap[signo][1] == '\0')) 369 breakwaitcmd = 1; 370 371 #ifndef NO_HISTORY 372 if (signo == SIGWINCH) 373 gotwinch = 1; 374 #endif 375 } 376 377 378 /* 379 * Called to execute a trap. Perhaps we should avoid entering new trap 380 * handlers while we are executing a trap handler. 381 */ 382 void 383 dotrap(void) 384 { 385 int i; 386 int savestatus; 387 388 in_dotrap++; 389 for (;;) { 390 for (i = 1; i < NSIG; i++) { 391 if (gotsig[i]) { 392 gotsig[i] = 0; 393 if (trap[i]) { 394 /* 395 * Ignore SIGCHLD to avoid infinite recursion 396 * if the trap action does a fork. 397 */ 398 if (i == SIGCHLD) 399 ignore_sigchld++; 400 savestatus = exitstatus; 401 evalstring(trap[i]); 402 exitstatus = savestatus; 403 if (i == SIGCHLD) 404 ignore_sigchld--; 405 } 406 break; 407 } 408 } 409 if (i >= NSIG) 410 break; 411 } 412 in_dotrap--; 413 pendingsigs = 0; 414 } 415 416 417 /* 418 * Controls whether the shell is interactive or not. 419 */ 420 void 421 setinteractive(int on) 422 { 423 static int is_interactive = -1; 424 425 if (on == is_interactive) 426 return; 427 setsignal(SIGINT); 428 setsignal(SIGQUIT); 429 setsignal(SIGTERM); 430 #ifndef NO_HISTORY 431 setsignal(SIGWINCH); 432 #endif 433 is_interactive = on; 434 } 435 436 437 /* 438 * Called to exit the shell. 439 */ 440 void 441 exitshell(int status) 442 { 443 struct jmploc loc1, loc2; 444 char *p; 445 446 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 447 if (setjmp(loc1.loc)) { 448 goto l1; 449 } 450 if (setjmp(loc2.loc)) { 451 goto l2; 452 } 453 handler = &loc1; 454 if ((p = trap[0]) != NULL && *p != '\0') { 455 trap[0] = NULL; 456 evalstring(p); 457 } 458 l1: handler = &loc2; /* probably unnecessary */ 459 flushall(); 460 #if JOBS 461 setjobctl(0); 462 #endif 463 l2: _exit(status); 464 } 465