1 /* $NetBSD: trap.c,v 1.28 2002/11/24 22:35:43 christos 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 1.28 2002/11/24 22:35:43 christos 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(int, sig_t *); 86 87 /* 88 * return the signal number described by `p' (as a number or a name) 89 * or -1 if it isn't one 90 */ 91 92 static int 93 signame_to_signum(const char *p) 94 { 95 int i; 96 97 if (is_number(p)) 98 return number(p); 99 100 if (strcasecmp(p, "exit") == 0 ) 101 return 0; 102 103 if (strncasecmp(p, "sig", 3) == 0) 104 p += 3; 105 106 for (i = 0; i < NSIG; ++i) 107 if (strcasecmp (p, sys_signame[i]) == 0) 108 return i; 109 return -1; 110 } 111 112 /* 113 * Print a list of valid signal names 114 */ 115 static void 116 printsignals(void) 117 { 118 int n; 119 120 out1str("EXIT "); 121 122 for (n = 1; n < NSIG; n++) { 123 out1fmt("%s", sys_signame[n]); 124 if ((n == NSIG/2) || n == (NSIG - 1)) 125 out1str("\n"); 126 else 127 out1c(' '); 128 } 129 } 130 131 /* 132 * The trap builtin. 133 */ 134 135 int 136 trapcmd(int argc, char **argv) 137 { 138 char *action; 139 char **ap; 140 int signo; 141 142 if (argc <= 1) { 143 for (signo = 0 ; signo <= NSIG ; signo++) { 144 if (trap[signo] != NULL) 145 out1fmt("trap -- '%s' %s\n", trap[signo], 146 (signo) ? sys_signame[signo] : "EXIT"); 147 } 148 return 0; 149 } 150 ap = argv + 1; 151 152 action = NULL; 153 154 if (strcmp(*ap, "--") == 0) 155 if (*++ap == NULL) 156 return 0; 157 158 if (signame_to_signum(*ap) == -1) { 159 if ((*ap)[0] =='-') { 160 if ((*ap)[1] == NULL) 161 ap++; 162 else if ((*ap)[1] == 'l' && (*ap)[2] == NULL) { 163 printsignals(); 164 return 0; 165 } 166 else 167 error("bad option %s\n", *ap); 168 } 169 else 170 action = *ap++; 171 } 172 173 while (*ap) { 174 if (is_number(*ap)) 175 signo = number(*ap); 176 else 177 signo = signame_to_signum(*ap); 178 179 if (signo < 0 || signo > NSIG) 180 error("%s: bad trap", *ap); 181 182 INTOFF; 183 if (action) 184 action = savestr(action); 185 186 if (trap[signo]) 187 ckfree(trap[signo]); 188 189 trap[signo] = action; 190 191 if (signo != 0) 192 setsignal(signo, 0); 193 INTON; 194 ap++; 195 } 196 return 0; 197 } 198 199 200 201 /* 202 * Clear traps on a fork or vfork. 203 * Takes one arg vfork, to tell it to not be destructive of 204 * the parents variables. 205 */ 206 207 void 208 clear_traps(int vforked) 209 { 210 char **tp; 211 212 for (tp = trap ; tp <= &trap[NSIG] ; tp++) { 213 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 214 INTOFF; 215 if (!vforked) { 216 ckfree(*tp); 217 *tp = NULL; 218 } 219 if (tp != &trap[0]) 220 setsignal(tp - trap, vforked); 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(int signo, int vforked) 235 { 236 int action; 237 sig_t sigact = SIG_DFL; 238 char *t, tsig; 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 (rootshell && !vforked && action == S_DFL) { 247 switch (signo) { 248 case SIGINT: 249 if (iflag || minusc || sflag == 0) 250 action = S_CATCH; 251 break; 252 case SIGQUIT: 253 #ifdef DEBUG 254 if (debug) 255 break; 256 #endif 257 /* FALLTHROUGH */ 258 case SIGTERM: 259 if (iflag) 260 action = S_IGN; 261 break; 262 #if JOBS 263 case SIGTSTP: 264 case SIGTTOU: 265 if (mflag) 266 action = S_IGN; 267 break; 268 #endif 269 } 270 } 271 272 t = &sigmode[signo - 1]; 273 tsig = *t; 274 if (tsig == 0) { 275 /* 276 * current setting unknown 277 */ 278 if (!getsigaction(signo, &sigact)) { 279 /* 280 * Pretend it worked; maybe we should give a warning 281 * here, but other shells don't. We don't alter 282 * sigmode, so that we retry every time. 283 */ 284 return 0; 285 } 286 if (sigact == SIG_IGN) { 287 if (mflag && (signo == SIGTSTP || 288 signo == SIGTTIN || signo == SIGTTOU)) { 289 tsig = S_IGN; /* don't hard ignore these */ 290 } else 291 tsig = S_HARD_IGN; 292 } else { 293 tsig = S_RESET; /* force to be set */ 294 } 295 } 296 if (tsig == S_HARD_IGN || tsig == action) 297 return 0; 298 switch (action) { 299 case S_DFL: sigact = SIG_DFL; break; 300 case S_CATCH: sigact = onsig; break; 301 case S_IGN: sigact = SIG_IGN; break; 302 } 303 if (!vforked) 304 *t = action; 305 siginterrupt(signo, 1); 306 return (long)signal(signo, sigact); 307 } 308 309 /* 310 * Return the current setting for sig w/o changing it. 311 */ 312 static int 313 getsigaction(int signo, sig_t *sigact) 314 { 315 struct sigaction sa; 316 317 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 318 return 0; 319 *sigact = (sig_t) sa.sa_handler; 320 return 1; 321 } 322 323 /* 324 * Ignore a signal. 325 */ 326 327 void 328 ignoresig(int signo, int vforked) 329 { 330 if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) { 331 signal(signo, SIG_IGN); 332 } 333 if (!vforked) 334 sigmode[signo - 1] = S_HARD_IGN; 335 } 336 337 338 #ifdef mkinit 339 INCLUDE <signal.h> 340 INCLUDE "trap.h" 341 342 SHELLPROC { 343 char *sm; 344 345 clear_traps(0); 346 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 347 if (*sm == S_IGN) 348 *sm = S_HARD_IGN; 349 } 350 } 351 #endif 352 353 354 355 /* 356 * Signal handler. 357 */ 358 359 void 360 onsig(int signo) 361 { 362 signal(signo, onsig); 363 if (signo == SIGINT && trap[SIGINT] == NULL) { 364 onint(); 365 return; 366 } 367 gotsig[signo - 1] = 1; 368 pendingsigs++; 369 } 370 371 372 373 /* 374 * Called to execute a trap. Perhaps we should avoid entering new trap 375 * handlers while we are executing a trap handler. 376 */ 377 378 void 379 dotrap(void) 380 { 381 int i; 382 int savestatus; 383 384 for (;;) { 385 for (i = 1 ; ; i++) { 386 if (gotsig[i - 1]) 387 break; 388 if (i >= NSIG) 389 goto done; 390 } 391 gotsig[i - 1] = 0; 392 savestatus=exitstatus; 393 evalstring(trap[i], 0); 394 exitstatus=savestatus; 395 } 396 done: 397 pendingsigs = 0; 398 } 399 400 401 402 /* 403 * Controls whether the shell is interactive or not. 404 */ 405 406 407 void 408 setinteractive(int on) 409 { 410 static int is_interactive; 411 412 if (on == is_interactive) 413 return; 414 setsignal(SIGINT, 0); 415 setsignal(SIGQUIT, 0); 416 setsignal(SIGTERM, 0); 417 is_interactive = on; 418 } 419 420 421 422 /* 423 * Called to exit the shell. 424 */ 425 426 void 427 exitshell(int status) 428 { 429 struct jmploc loc1, loc2; 430 char *p; 431 432 TRACE(("pid %d, exitshell(%d)\n", getpid(), status)); 433 if (setjmp(loc1.loc)) { 434 goto l1; 435 } 436 if (setjmp(loc2.loc)) { 437 goto l2; 438 } 439 handler = &loc1; 440 if ((p = trap[0]) != NULL && *p != '\0') { 441 trap[0] = NULL; 442 evalstring(p, 0); 443 } 444 l1: handler = &loc2; /* probably unnecessary */ 445 flushall(); 446 #if JOBS 447 setjobctl(0); 448 #endif 449 l2: _exit(status); 450 /* NOTREACHED */ 451 } 452