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 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], sys_signame[signo]); 162 } else { 163 out1fmt("trap -- '%s' %d\n", 164 trap[signo], signo); 165 } 166 } 167 } 168 return 0; 169 } 170 action = NULL; 171 if (*++argv && strcmp(*argv, "--") == 0) 172 argv++; 173 if (*argv && sigstring_to_signum(*argv) == -1) { 174 if ((*argv)[0] != '-') { 175 action = *argv; 176 argv++; 177 } else if ((*argv)[1] == '\0') { 178 argv++; 179 } else if ((*argv)[1] == 'l' && (*argv)[2] == '\0') { 180 printsignals(); 181 return 0; 182 } else { 183 error("bad option %s", *argv); 184 } 185 } 186 while (*argv) { 187 if ((signo = sigstring_to_signum(*argv)) == -1) 188 error("bad signal %s", *argv); 189 INTOFF; 190 if (action) 191 action = savestr(action); 192 if (trap[signo]) 193 ckfree(trap[signo]); 194 trap[signo] = action; 195 if (signo != 0) 196 setsignal(signo); 197 INTON; 198 argv++; 199 } 200 return 0; 201 } 202 203 204 /* 205 * Clear traps on a fork. 206 */ 207 void 208 clear_traps(void) 209 { 210 char *volatile *tp; 211 212 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 213 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 214 INTOFF; 215 ckfree(*tp); 216 *tp = NULL; 217 if (tp != &trap[0]) 218 setsignal(tp - trap); 219 INTON; 220 } 221 } 222 } 223 224 225 /* 226 * Set the signal handler for the specified signal. The routine figures 227 * out what it should be set to. 228 */ 229 void 230 setsignal(int signo) 231 { 232 int action; 233 sig_t sig, sigact = SIG_DFL; 234 char *t; 235 236 if ((t = trap[signo]) == NULL) 237 action = S_DFL; 238 else if (*t != '\0') 239 action = S_CATCH; 240 else 241 action = S_IGN; 242 if (action == S_DFL) { 243 switch (signo) { 244 case SIGINT: 245 action = S_CATCH; 246 break; 247 case SIGQUIT: 248 #ifdef DEBUG 249 { 250 extern int debug; 251 252 if (debug) 253 break; 254 } 255 #endif 256 action = S_CATCH; 257 break; 258 case SIGTERM: 259 if (rootshell && iflag) 260 action = S_IGN; 261 break; 262 #if JOBS 263 case SIGTSTP: 264 case SIGTTOU: 265 if (rootshell && mflag) 266 action = S_IGN; 267 break; 268 #endif 269 #ifndef NO_HISTORY 270 case SIGWINCH: 271 if (rootshell && iflag) 272 action = S_CATCH; 273 break; 274 #endif 275 } 276 } 277 278 t = &sigmode[signo]; 279 if (*t == 0) { 280 /* 281 * current setting unknown 282 */ 283 if (!getsigaction(signo, &sigact)) { 284 /* 285 * Pretend it worked; maybe we should give a warning 286 * here, but other shells don't. We don't alter 287 * sigmode, so that we retry every time. 288 */ 289 return; 290 } 291 if (sigact == SIG_IGN) { 292 if (mflag && (signo == SIGTSTP || 293 signo == SIGTTIN || signo == SIGTTOU)) { 294 *t = S_IGN; /* don't hard ignore these */ 295 } else 296 *t = S_HARD_IGN; 297 } else { 298 *t = S_RESET; /* force to be set */ 299 } 300 } 301 if (*t == S_HARD_IGN || *t == action) 302 return; 303 switch (action) { 304 case S_DFL: sigact = SIG_DFL; break; 305 case S_CATCH: sigact = onsig; break; 306 case S_IGN: sigact = SIG_IGN; break; 307 } 308 *t = action; 309 sig = signal(signo, sigact); 310 if (sig != SIG_ERR && action == S_CATCH) 311 siginterrupt(signo, 1); 312 } 313 314 315 /* 316 * Return the current setting for sig w/o changing it. 317 */ 318 static int 319 getsigaction(int signo, sig_t *sigact) 320 { 321 struct sigaction sa; 322 323 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 324 return 0; 325 *sigact = (sig_t) sa.sa_handler; 326 return 1; 327 } 328 329 330 /* 331 * Ignore a signal. 332 */ 333 void 334 ignoresig(int signo) 335 { 336 337 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) { 338 signal(signo, SIG_IGN); 339 } 340 sigmode[signo] = S_HARD_IGN; 341 } 342 343 344 #ifdef mkinit 345 INCLUDE <signal.h> 346 INCLUDE "trap.h" 347 348 SHELLPROC { 349 char *sm; 350 351 clear_traps(); 352 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 353 if (*sm == S_IGN) 354 *sm = S_HARD_IGN; 355 } 356 } 357 #endif 358 359 360 /* 361 * Signal handler. 362 */ 363 void 364 onsig(int signo) 365 { 366 367 if (signo == SIGINT && trap[SIGINT] == NULL) { 368 onint(); 369 return; 370 } 371 372 if (signo != SIGCHLD || !ignore_sigchld) 373 gotsig[signo] = 1; 374 pendingsigs++; 375 376 /* If we are currently in a wait builtin, prepare to break it */ 377 if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0) 378 breakwaitcmd = 1; 379 /* 380 * If a trap is set, not ignored and not the null command, we need 381 * to make sure traps are executed even when a child blocks signals. 382 */ 383 if (Tflag && 384 trap[signo] != NULL && 385 ! trap[signo][0] == '\0' && 386 ! (trap[signo][0] == ':' && trap[signo][1] == '\0')) 387 breakwaitcmd = 1; 388 389 #ifndef NO_HISTORY 390 if (signo == SIGWINCH) 391 gotwinch = 1; 392 #endif 393 } 394 395 396 /* 397 * Called to execute a trap. Perhaps we should avoid entering new trap 398 * handlers while we are executing a trap handler. 399 */ 400 void 401 dotrap(void) 402 { 403 int i; 404 int savestatus; 405 406 in_dotrap++; 407 for (;;) { 408 for (i = 1; i < NSIG; i++) { 409 if (gotsig[i]) { 410 gotsig[i] = 0; 411 if (trap[i]) { 412 /* 413 * Ignore SIGCHLD to avoid infinite 414 * recursion if the trap action does 415 * 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