1 /* $NetBSD: trap.c,v 1.26 2001/03/18 04:04:23 wulf Exp $ */ 2 3 /*- 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Kenneth Almquist. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #ifndef lint 41 #if 0 42 static char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95"; 43 #else 44 __RCSID("$NetBSD: trap.c,v 1.26 2001/03/18 04:04:23 wulf Exp $"); 45 #endif 46 #endif /* not lint */ 47 48 #include <signal.h> 49 #include <unistd.h> 50 #include <stdlib.h> 51 52 #include "shell.h" 53 #include "main.h" 54 #include "nodes.h" /* for other headers */ 55 #include "eval.h" 56 #include "jobs.h" 57 #include "show.h" 58 #include "options.h" 59 #include "syntax.h" 60 #include "output.h" 61 #include "memalloc.h" 62 #include "error.h" 63 #include "trap.h" 64 #include "mystring.h" 65 66 67 /* 68 * Sigmode records the current value of the signal handlers for the various 69 * modes. A value of zero means that the current handler is not known. 70 * S_HARD_IGN indicates that the signal was ignored on entry to the shell, 71 */ 72 73 #define S_DFL 1 /* default signal handling (SIG_DFL) */ 74 #define S_CATCH 2 /* signal is caught */ 75 #define S_IGN 3 /* signal is ignored (SIG_IGN) */ 76 #define S_HARD_IGN 4 /* signal is ignored permenantly */ 77 #define S_RESET 5 /* temporary - to reset a hard ignored sig */ 78 79 80 char *trap[NSIG+1]; /* trap handler commands */ 81 MKINIT char sigmode[NSIG]; /* current value of signal */ 82 char gotsig[NSIG]; /* indicates specified signal received */ 83 int pendingsigs; /* indicates some signal received */ 84 85 static int getsigaction __P((int, sig_t *)); 86 static int signame_to_signum __P((const char *)); 87 void printsignals __P((void)); 88 89 /* 90 * return the signal number described by `p' (as a number or a name) 91 * or -1 if it isn't one 92 */ 93 94 static int 95 signame_to_signum(p) 96 const char *p; 97 { 98 int i; 99 100 if (is_number(p)) 101 return number(p); 102 103 if (strcasecmp(p, "exit") == 0 ) 104 return 0; 105 106 if (strncasecmp(p, "sig", 3) == 0) 107 p += 3; 108 109 for (i = 0; i < NSIG; ++i) 110 if (strcasecmp (p, sys_signame[i]) == 0) 111 return i; 112 return -1; 113 } 114 115 /* 116 * Print a list of valid signal names 117 */ 118 void 119 printsignals(void) 120 { 121 int n; 122 123 out1str("EXIT "); 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 * The trap builtin. 136 */ 137 138 int 139 trapcmd(argc, argv) 140 int argc; 141 char **argv; 142 { 143 char *action; 144 char **ap; 145 int signo; 146 147 if (argc <= 1) { 148 for (signo = 0 ; signo <= NSIG ; signo++) { 149 if (trap[signo] != NULL) 150 out1fmt("trap -- '%s' %s\n", trap[signo], 151 (signo) ? sys_signame[signo] : "EXIT"); 152 } 153 return 0; 154 } 155 ap = argv + 1; 156 157 action = NULL; 158 159 if (strcmp(*ap, "--") == 0) 160 if (*++ap == NULL) 161 return 0; 162 163 if (signame_to_signum(*ap) == -1) { 164 if ((*ap)[0] =='-') { 165 if ((*ap)[1] == NULL) 166 ap++; 167 else if ((*ap)[1] == 'l' && (*ap)[2] == NULL) { 168 printsignals(); 169 return 0; 170 } 171 else 172 error("bad option %s\n", *ap); 173 } 174 else 175 action = *ap++; 176 } 177 178 while (*ap) { 179 if (is_number(*ap)) 180 signo = number(*ap); 181 else 182 signo = signame_to_signum(*ap); 183 184 if (signo < 0 || signo > NSIG) 185 error("%s: bad trap", *ap); 186 187 INTOFF; 188 if (action) 189 action = savestr(action); 190 191 if (trap[signo]) 192 ckfree(trap[signo]); 193 194 trap[signo] = action; 195 196 if (signo != 0) 197 setsignal(signo); 198 INTON; 199 ap++; 200 } 201 return 0; 202 } 203 204 205 206 /* 207 * Clear traps on a fork. 208 */ 209 210 void 211 clear_traps() { 212 char **tp; 213 214 for (tp = trap ; tp <= &trap[NSIG] ; tp++) { 215 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 216 INTOFF; 217 ckfree(*tp); 218 *tp = NULL; 219 if (tp != &trap[0]) 220 setsignal(tp - trap); 221 INTON; 222 } 223 } 224 } 225 226 227 228 /* 229 * Set the signal handler for the specified signal. The routine figures 230 * out what it should be set to. 231 */ 232 233 long 234 setsignal(signo) 235 int signo; 236 { 237 int action; 238 sig_t sigact = SIG_DFL; 239 char *t; 240 241 if ((t = trap[signo]) == NULL) 242 action = S_DFL; 243 else if (*t != '\0') 244 action = S_CATCH; 245 else 246 action = S_IGN; 247 if (rootshell && action == S_DFL) { 248 switch (signo) { 249 case SIGINT: 250 if (iflag || minusc || sflag == 0) 251 action = S_CATCH; 252 break; 253 case SIGQUIT: 254 #ifdef DEBUG 255 { 256 extern int debug; 257 258 if (debug) 259 break; 260 } 261 #endif 262 /* FALLTHROUGH */ 263 case SIGTERM: 264 if (iflag) 265 action = S_IGN; 266 break; 267 #if JOBS 268 case SIGTSTP: 269 case SIGTTOU: 270 if (mflag) 271 action = S_IGN; 272 break; 273 #endif 274 } 275 } 276 277 t = &sigmode[signo - 1]; 278 if (*t == 0) { 279 /* 280 * current setting unknown 281 */ 282 if (!getsigaction(signo, &sigact)) { 283 /* 284 * Pretend it worked; maybe we should give a warning 285 * here, but other shells don't. We don't alter 286 * sigmode, so that we retry every time. 287 */ 288 return 0; 289 } 290 if (sigact == SIG_IGN) { 291 if (mflag && (signo == SIGTSTP || 292 signo == SIGTTIN || signo == SIGTTOU)) { 293 *t = S_IGN; /* don't hard ignore these */ 294 } else 295 *t = S_HARD_IGN; 296 } else { 297 *t = S_RESET; /* force to be set */ 298 } 299 } 300 if (*t == S_HARD_IGN || *t == action) 301 return 0; 302 switch (action) { 303 case S_DFL: sigact = SIG_DFL; break; 304 case S_CATCH: sigact = onsig; break; 305 case S_IGN: sigact = SIG_IGN; break; 306 } 307 *t = action; 308 siginterrupt(signo, 1); 309 return (long)signal(signo, sigact); 310 } 311 312 /* 313 * Return the current setting for sig w/o changing it. 314 */ 315 static int 316 getsigaction(signo, sigact) 317 int signo; 318 sig_t *sigact; 319 { 320 struct sigaction sa; 321 322 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 323 return 0; 324 *sigact = (sig_t) sa.sa_handler; 325 return 1; 326 } 327 328 /* 329 * Ignore a signal. 330 */ 331 332 void 333 ignoresig(signo) 334 int signo; 335 { 336 if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) { 337 signal(signo, SIG_IGN); 338 } 339 sigmode[signo - 1] = S_HARD_IGN; 340 } 341 342 343 #ifdef mkinit 344 INCLUDE <signal.h> 345 INCLUDE "trap.h" 346 347 SHELLPROC { 348 char *sm; 349 350 clear_traps(); 351 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 352 if (*sm == S_IGN) 353 *sm = S_HARD_IGN; 354 } 355 } 356 #endif 357 358 359 360 /* 361 * Signal handler. 362 */ 363 364 void 365 onsig(signo) 366 int signo; 367 { 368 signal(signo, onsig); 369 if (signo == SIGINT && trap[SIGINT] == NULL) { 370 onint(); 371 return; 372 } 373 gotsig[signo - 1] = 1; 374 pendingsigs++; 375 } 376 377 378 379 /* 380 * Called to execute a trap. Perhaps we should avoid entering new trap 381 * handlers while we are executing a trap handler. 382 */ 383 384 void 385 dotrap() { 386 int i; 387 int savestatus; 388 389 for (;;) { 390 for (i = 1 ; ; i++) { 391 if (gotsig[i - 1]) 392 break; 393 if (i >= NSIG) 394 goto done; 395 } 396 gotsig[i - 1] = 0; 397 savestatus=exitstatus; 398 evalstring(trap[i], 0); 399 exitstatus=savestatus; 400 } 401 done: 402 pendingsigs = 0; 403 } 404 405 406 407 /* 408 * Controls whether the shell is interactive or not. 409 */ 410 411 412 void 413 setinteractive(on) 414 int on; 415 { 416 static int is_interactive; 417 418 if (on == is_interactive) 419 return; 420 setsignal(SIGINT); 421 setsignal(SIGQUIT); 422 setsignal(SIGTERM); 423 is_interactive = on; 424 } 425 426 427 428 /* 429 * Called to exit the shell. 430 */ 431 432 void 433 exitshell(status) 434 int status; 435 { 436 struct jmploc loc1, loc2; 437 char *p; 438 439 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 440 if (setjmp(loc1.loc)) { 441 goto l1; 442 } 443 if (setjmp(loc2.loc)) { 444 goto l2; 445 } 446 handler = &loc1; 447 if ((p = trap[0]) != NULL && *p != '\0') { 448 trap[0] = NULL; 449 evalstring(p, 0); 450 } 451 l1: handler = &loc2; /* probably unnecessary */ 452 flushall(); 453 #if JOBS 454 setjobctl(0); 455 #endif 456 l2: _exit(status); 457 /* NOTREACHED */ 458 } 459