1 /* $NetBSD: trap.c,v 1.30 2003/08/26 18:13:25 jmmv 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #ifndef lint 37 #if 0 38 static char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95"; 39 #else 40 __RCSID("$NetBSD: trap.c,v 1.30 2003/08/26 18:13:25 jmmv Exp $"); 41 #endif 42 #endif /* not lint */ 43 44 #include <signal.h> 45 #include <unistd.h> 46 #include <stdlib.h> 47 48 #include "shell.h" 49 #include "main.h" 50 #include "nodes.h" /* for other headers */ 51 #include "eval.h" 52 #include "jobs.h" 53 #include "show.h" 54 #include "options.h" 55 #include "syntax.h" 56 #include "output.h" 57 #include "memalloc.h" 58 #include "error.h" 59 #include "trap.h" 60 #include "mystring.h" 61 62 63 /* 64 * Sigmode records the current value of the signal handlers for the various 65 * modes. A value of zero means that the current handler is not known. 66 * S_HARD_IGN indicates that the signal was ignored on entry to the shell, 67 */ 68 69 #define S_DFL 1 /* default signal handling (SIG_DFL) */ 70 #define S_CATCH 2 /* signal is caught */ 71 #define S_IGN 3 /* signal is ignored (SIG_IGN) */ 72 #define S_HARD_IGN 4 /* signal is ignored permenantly */ 73 #define S_RESET 5 /* temporary - to reset a hard ignored sig */ 74 75 76 char *trap[NSIG+1]; /* trap handler commands */ 77 MKINIT char sigmode[NSIG]; /* current value of signal */ 78 char gotsig[NSIG]; /* indicates specified signal received */ 79 int pendingsigs; /* indicates some signal received */ 80 81 static int getsigaction(int, sig_t *); 82 83 /* 84 * return the signal number described by `p' (as a number or a name) 85 * or -1 if it isn't one 86 */ 87 88 static int 89 signame_to_signum(const char *p) 90 { 91 int i; 92 93 if (is_number(p)) 94 return number(p); 95 96 if (strcasecmp(p, "exit") == 0 ) 97 return 0; 98 99 if (strncasecmp(p, "sig", 3) == 0) 100 p += 3; 101 102 for (i = 0; i < NSIG; ++i) 103 if (strcasecmp (p, sys_signame[i]) == 0) 104 return i; 105 return -1; 106 } 107 108 /* 109 * Print a list of valid signal names 110 */ 111 static void 112 printsignals(void) 113 { 114 int n; 115 116 out1str("EXIT "); 117 118 for (n = 1; n < NSIG; n++) { 119 out1fmt("%s", sys_signame[n]); 120 if ((n == NSIG/2) || n == (NSIG - 1)) 121 out1str("\n"); 122 else 123 out1c(' '); 124 } 125 } 126 127 /* 128 * The trap builtin. 129 */ 130 131 int 132 trapcmd(int argc, char **argv) 133 { 134 char *action; 135 char **ap; 136 int signo; 137 138 if (argc <= 1) { 139 for (signo = 0 ; signo <= NSIG ; signo++) { 140 if (trap[signo] != NULL) 141 out1fmt("trap -- '%s' %s\n", trap[signo], 142 (signo) ? sys_signame[signo] : "EXIT"); 143 } 144 return 0; 145 } 146 ap = argv + 1; 147 148 action = NULL; 149 150 if (strcmp(*ap, "--") == 0) 151 if (*++ap == NULL) 152 return 0; 153 154 if (signame_to_signum(*ap) == -1) { 155 if ((*ap)[0] == '-') { 156 if ((*ap)[1] == '\0') 157 ap++; 158 else if ((*ap)[1] == 'l' && (*ap)[2] == '\0') { 159 printsignals(); 160 return 0; 161 } 162 else 163 error("bad option %s\n", *ap); 164 } 165 else 166 action = *ap++; 167 } 168 169 while (*ap) { 170 if (is_number(*ap)) 171 signo = number(*ap); 172 else 173 signo = signame_to_signum(*ap); 174 175 if (signo < 0 || signo > NSIG) 176 error("%s: bad trap", *ap); 177 178 INTOFF; 179 if (action) 180 action = savestr(action); 181 182 if (trap[signo]) 183 ckfree(trap[signo]); 184 185 trap[signo] = action; 186 187 if (signo != 0) 188 setsignal(signo, 0); 189 INTON; 190 ap++; 191 } 192 return 0; 193 } 194 195 196 197 /* 198 * Clear traps on a fork or vfork. 199 * Takes one arg vfork, to tell it to not be destructive of 200 * the parents variables. 201 */ 202 203 void 204 clear_traps(int vforked) 205 { 206 char **tp; 207 208 for (tp = trap ; tp <= &trap[NSIG] ; tp++) { 209 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 210 INTOFF; 211 if (!vforked) { 212 ckfree(*tp); 213 *tp = NULL; 214 } 215 if (tp != &trap[0]) 216 setsignal(tp - trap, vforked); 217 INTON; 218 } 219 } 220 } 221 222 223 224 /* 225 * Set the signal handler for the specified signal. The routine figures 226 * out what it should be set to. 227 */ 228 229 long 230 setsignal(int signo, int vforked) 231 { 232 int action; 233 sig_t sigact = SIG_DFL; 234 char *t, tsig; 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 (rootshell && !vforked && action == S_DFL) { 243 switch (signo) { 244 case SIGINT: 245 if (iflag || minusc || sflag == 0) 246 action = S_CATCH; 247 break; 248 case SIGQUIT: 249 #ifdef DEBUG 250 if (debug) 251 break; 252 #endif 253 /* FALLTHROUGH */ 254 case SIGTERM: 255 if (iflag) 256 action = S_IGN; 257 break; 258 #if JOBS 259 case SIGTSTP: 260 case SIGTTOU: 261 if (mflag) 262 action = S_IGN; 263 break; 264 #endif 265 } 266 } 267 268 t = &sigmode[signo - 1]; 269 tsig = *t; 270 if (tsig == 0) { 271 /* 272 * current setting unknown 273 */ 274 if (!getsigaction(signo, &sigact)) { 275 /* 276 * Pretend it worked; maybe we should give a warning 277 * here, but other shells don't. We don't alter 278 * sigmode, so that we retry every time. 279 */ 280 return 0; 281 } 282 if (sigact == SIG_IGN) { 283 if (mflag && (signo == SIGTSTP || 284 signo == SIGTTIN || signo == SIGTTOU)) { 285 tsig = S_IGN; /* don't hard ignore these */ 286 } else 287 tsig = S_HARD_IGN; 288 } else { 289 tsig = S_RESET; /* force to be set */ 290 } 291 } 292 if (tsig == S_HARD_IGN || tsig == action) 293 return 0; 294 switch (action) { 295 case S_DFL: sigact = SIG_DFL; break; 296 case S_CATCH: sigact = onsig; break; 297 case S_IGN: sigact = SIG_IGN; break; 298 } 299 if (!vforked) 300 *t = action; 301 siginterrupt(signo, 1); 302 return (long)signal(signo, sigact); 303 } 304 305 /* 306 * Return the current setting for sig w/o changing it. 307 */ 308 static int 309 getsigaction(int signo, sig_t *sigact) 310 { 311 struct sigaction sa; 312 313 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 314 return 0; 315 *sigact = (sig_t) sa.sa_handler; 316 return 1; 317 } 318 319 /* 320 * Ignore a signal. 321 */ 322 323 void 324 ignoresig(int signo, int vforked) 325 { 326 if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) { 327 signal(signo, SIG_IGN); 328 } 329 if (!vforked) 330 sigmode[signo - 1] = S_HARD_IGN; 331 } 332 333 334 #ifdef mkinit 335 INCLUDE <signal.h> 336 INCLUDE "trap.h" 337 338 SHELLPROC { 339 char *sm; 340 341 clear_traps(0); 342 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 343 if (*sm == S_IGN) 344 *sm = S_HARD_IGN; 345 } 346 } 347 #endif 348 349 350 351 /* 352 * Signal handler. 353 */ 354 355 void 356 onsig(int signo) 357 { 358 signal(signo, onsig); 359 if (signo == SIGINT && trap[SIGINT] == NULL) { 360 onint(); 361 return; 362 } 363 gotsig[signo - 1] = 1; 364 pendingsigs++; 365 } 366 367 368 369 /* 370 * Called to execute a trap. Perhaps we should avoid entering new trap 371 * handlers while we are executing a trap handler. 372 */ 373 374 void 375 dotrap(void) 376 { 377 int i; 378 int savestatus; 379 380 for (;;) { 381 for (i = 1 ; ; i++) { 382 if (gotsig[i - 1]) 383 break; 384 if (i >= NSIG) 385 goto done; 386 } 387 gotsig[i - 1] = 0; 388 savestatus=exitstatus; 389 evalstring(trap[i], 0); 390 exitstatus=savestatus; 391 } 392 done: 393 pendingsigs = 0; 394 } 395 396 397 398 /* 399 * Controls whether the shell is interactive or not. 400 */ 401 402 403 void 404 setinteractive(int on) 405 { 406 static int is_interactive; 407 408 if (on == is_interactive) 409 return; 410 setsignal(SIGINT, 0); 411 setsignal(SIGQUIT, 0); 412 setsignal(SIGTERM, 0); 413 is_interactive = on; 414 } 415 416 417 418 /* 419 * Called to exit the shell. 420 */ 421 422 void 423 exitshell(int status) 424 { 425 struct jmploc loc1, loc2; 426 char *p; 427 428 TRACE(("pid %d, exitshell(%d)\n", getpid(), status)); 429 if (setjmp(loc1.loc)) { 430 goto l1; 431 } 432 if (setjmp(loc2.loc)) { 433 goto l2; 434 } 435 handler = &loc1; 436 if ((p = trap[0]) != NULL && *p != '\0') { 437 trap[0] = NULL; 438 evalstring(p, 0); 439 } 440 l1: handler = &loc2; /* probably unnecessary */ 441 flushall(); 442 #if JOBS 443 setjobctl(0); 444 #endif 445 l2: _exit(status); 446 /* NOTREACHED */ 447 } 448