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("$FreeBSD$"); 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 * Note: the signal number may exceed NSIG. 94 */ 95 static int 96 sigstring_to_signum(char *sig) 97 { 98 99 if (is_number(sig)) { 100 int signo; 101 102 signo = atoi(sig); 103 return ((signo >= 0 && signo < NSIG) ? signo : (-1)); 104 } else if (strcasecmp(sig, "exit") == 0) { 105 return (0); 106 } else { 107 int n; 108 109 if (strncasecmp(sig, "sig", 3) == 0) 110 sig += 3; 111 for (n = 1; n < sys_nsig; n++) 112 if (sys_signame[n] && 113 strcasecmp(sys_signame[n], sig) == 0) 114 return (n); 115 } 116 return (-1); 117 } 118 119 120 /* 121 * Print a list of valid signal names. 122 */ 123 static void 124 printsignals(void) 125 { 126 int n, outlen; 127 128 outlen = 0; 129 for (n = 1; n < sys_nsig; n++) { 130 if (sys_signame[n]) { 131 out1fmt("%s", sys_signame[n]); 132 outlen += strlen(sys_signame[n]); 133 } else { 134 out1fmt("%d", n); 135 outlen += 3; /* good enough */ 136 } 137 ++outlen; 138 if (outlen > 70 || n == sys_nsig - 1) { 139 out1str("\n"); 140 outlen = 0; 141 } else { 142 out1c(' '); 143 } 144 } 145 } 146 147 148 /* 149 * The trap builtin. 150 */ 151 int 152 trapcmd(int argc, char **argv) 153 { 154 char *action; 155 int signo; 156 157 if (argc <= 1) { 158 for (signo = 0 ; signo < sys_nsig ; signo++) { 159 if (signo < NSIG && trap[signo] != NULL) { 160 if (signo == 0) { 161 out1fmt("trap -- '%s' %s\n", 162 trap[signo], "exit"); 163 } else if (sys_signame[signo]) { 164 out1fmt("trap -- '%s' %s\n", 165 trap[signo], sys_signame[signo]); 166 } else { 167 out1fmt("trap -- '%s' %d\n", 168 trap[signo], signo); 169 } 170 } 171 } 172 return 0; 173 } 174 action = NULL; 175 if (*++argv && strcmp(*argv, "--") == 0) 176 argv++; 177 if (*argv && sigstring_to_signum(*argv) == -1) { 178 if ((*argv)[0] != '-') { 179 action = *argv; 180 argv++; 181 } else if ((*argv)[1] == '\0') { 182 argv++; 183 } else if ((*argv)[1] == 'l' && (*argv)[2] == '\0') { 184 printsignals(); 185 return 0; 186 } else { 187 error("bad option %s", *argv); 188 } 189 } 190 while (*argv) { 191 if ((signo = sigstring_to_signum(*argv)) == -1) 192 error("bad signal %s", *argv); 193 INTOFF; 194 if (action) 195 action = savestr(action); 196 if (trap[signo]) 197 ckfree(trap[signo]); 198 trap[signo] = action; 199 if (signo != 0) 200 setsignal(signo); 201 INTON; 202 argv++; 203 } 204 return 0; 205 } 206 207 208 /* 209 * Clear traps on a fork. 210 */ 211 void 212 clear_traps(void) 213 { 214 char *volatile *tp; 215 216 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 217 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 218 INTOFF; 219 ckfree(*tp); 220 *tp = NULL; 221 if (tp != &trap[0]) 222 setsignal(tp - trap); 223 INTON; 224 } 225 } 226 } 227 228 229 /* 230 * Set the signal handler for the specified signal. The routine figures 231 * out what it should be set to. 232 */ 233 void 234 setsignal(int signo) 235 { 236 int action; 237 sig_t sig, sigact = SIG_DFL; 238 char *t; 239 240 if ((t = trap[signo]) == NULL) 241 action = S_DFL; 242 else if (*t != '\0') 243 action = S_CATCH; 244 else 245 action = S_IGN; 246 if (action == S_DFL) { 247 switch (signo) { 248 case SIGINT: 249 action = S_CATCH; 250 break; 251 case SIGQUIT: 252 #ifdef DEBUG 253 { 254 extern int debug; 255 256 if (debug) 257 break; 258 } 259 #endif 260 action = S_CATCH; 261 break; 262 case SIGTERM: 263 if (rootshell && iflag) 264 action = S_IGN; 265 break; 266 #if JOBS 267 case SIGTSTP: 268 case SIGTTOU: 269 if (rootshell && mflag) 270 action = S_IGN; 271 break; 272 #endif 273 #ifndef NO_HISTORY 274 case SIGWINCH: 275 if (rootshell && iflag) 276 action = S_CATCH; 277 break; 278 #endif 279 } 280 } 281 282 t = &sigmode[signo]; 283 if (*t == 0) { 284 /* 285 * current setting unknown 286 */ 287 if (!getsigaction(signo, &sigact)) { 288 /* 289 * Pretend it worked; maybe we should give a warning 290 * here, but other shells don't. We don't alter 291 * sigmode, so that we retry every time. 292 */ 293 return; 294 } 295 if (sigact == SIG_IGN) { 296 if (mflag && (signo == SIGTSTP || 297 signo == SIGTTIN || signo == SIGTTOU)) { 298 *t = S_IGN; /* don't hard ignore these */ 299 } else 300 *t = S_HARD_IGN; 301 } else { 302 *t = S_RESET; /* force to be set */ 303 } 304 } 305 if (*t == S_HARD_IGN || *t == action) 306 return; 307 switch (action) { 308 case S_DFL: sigact = SIG_DFL; break; 309 case S_CATCH: sigact = onsig; break; 310 case S_IGN: sigact = SIG_IGN; break; 311 } 312 *t = action; 313 sig = signal(signo, sigact); 314 if (sig != SIG_ERR && action == S_CATCH) 315 siginterrupt(signo, 1); 316 } 317 318 319 /* 320 * Return the current setting for sig w/o changing it. 321 */ 322 static int 323 getsigaction(int signo, sig_t *sigact) 324 { 325 struct sigaction sa; 326 327 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 328 return 0; 329 *sigact = (sig_t) sa.sa_handler; 330 return 1; 331 } 332 333 334 /* 335 * Ignore a signal. 336 */ 337 void 338 ignoresig(int signo) 339 { 340 341 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) { 342 signal(signo, SIG_IGN); 343 } 344 sigmode[signo] = S_HARD_IGN; 345 } 346 347 348 #ifdef mkinit 349 INCLUDE <signal.h> 350 INCLUDE "trap.h" 351 352 SHELLPROC { 353 char *sm; 354 355 clear_traps(); 356 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 357 if (*sm == S_IGN) 358 *sm = S_HARD_IGN; 359 } 360 } 361 #endif 362 363 364 /* 365 * Signal handler. 366 */ 367 void 368 onsig(int signo) 369 { 370 371 if (signo == SIGINT && trap[SIGINT] == NULL) { 372 onint(); 373 return; 374 } 375 376 if (signo != SIGCHLD || !ignore_sigchld) 377 gotsig[signo] = 1; 378 pendingsigs++; 379 380 /* If we are currently in a wait builtin, prepare to break it */ 381 if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0) 382 breakwaitcmd = 1; 383 /* 384 * If a trap is set, not ignored and not the null command, we need 385 * to make sure traps are executed even when a child blocks signals. 386 */ 387 if (Tflag && 388 trap[signo] != NULL && 389 ! trap[signo][0] == '\0' && 390 ! (trap[signo][0] == ':' && trap[signo][1] == '\0')) 391 breakwaitcmd = 1; 392 393 #ifndef NO_HISTORY 394 if (signo == SIGWINCH) 395 gotwinch = 1; 396 #endif 397 } 398 399 400 /* 401 * Called to execute a trap. Perhaps we should avoid entering new trap 402 * handlers while we are executing a trap handler. 403 */ 404 void 405 dotrap(void) 406 { 407 int i; 408 int savestatus; 409 410 in_dotrap++; 411 for (;;) { 412 for (i = 1; i < NSIG; i++) { 413 if (gotsig[i]) { 414 gotsig[i] = 0; 415 if (trap[i]) { 416 /* 417 * Ignore SIGCHLD to avoid infinite 418 * recursion if the trap action does 419 * a fork. 420 */ 421 if (i == SIGCHLD) 422 ignore_sigchld++; 423 savestatus = exitstatus; 424 evalstring(trap[i]); 425 exitstatus = savestatus; 426 if (i == SIGCHLD) 427 ignore_sigchld--; 428 } 429 break; 430 } 431 } 432 if (i >= NSIG) 433 break; 434 } 435 in_dotrap--; 436 pendingsigs = 0; 437 } 438 439 440 /* 441 * Controls whether the shell is interactive or not. 442 */ 443 void 444 setinteractive(int on) 445 { 446 static int is_interactive = -1; 447 448 if (on == is_interactive) 449 return; 450 setsignal(SIGINT); 451 setsignal(SIGQUIT); 452 setsignal(SIGTERM); 453 #ifndef NO_HISTORY 454 setsignal(SIGWINCH); 455 #endif 456 is_interactive = on; 457 } 458 459 460 /* 461 * Called to exit the shell. 462 */ 463 void 464 exitshell(int status) 465 { 466 struct jmploc loc1, loc2; 467 char *p; 468 469 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 470 if (setjmp(loc1.loc)) { 471 goto l1; 472 } 473 if (setjmp(loc2.loc)) { 474 goto l2; 475 } 476 handler = &loc1; 477 if ((p = trap[0]) != NULL && *p != '\0') { 478 trap[0] = NULL; 479 evalstring(p); 480 } 481 l1: handler = &loc2; /* probably unnecessary */ 482 flushall(); 483 #if JOBS 484 setjobctl(0); 485 #endif 486 l2: _exit(status); 487 } 488