1 /* $NetBSD: trap.c,v 1.31 2005/01/11 19:38:57 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. 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 1.31 2005/01/11 19:38:57 christos 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 #include "var.h" 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 -- "); 142 print_quoted(trap[signo]); 143 out1fmt(" %s\n", 144 (signo) ? sys_signame[signo] : "EXIT"); 145 } 146 return 0; 147 } 148 ap = argv + 1; 149 150 action = NULL; 151 152 if (strcmp(*ap, "--") == 0) 153 if (*++ap == NULL) 154 return 0; 155 156 if (signame_to_signum(*ap) == -1) { 157 if ((*ap)[0] == '-') { 158 if ((*ap)[1] == '\0') 159 ap++; 160 else if ((*ap)[1] == 'l' && (*ap)[2] == '\0') { 161 printsignals(); 162 return 0; 163 } 164 else 165 error("bad option %s\n", *ap); 166 } 167 else 168 action = *ap++; 169 } 170 171 while (*ap) { 172 if (is_number(*ap)) 173 signo = number(*ap); 174 else 175 signo = signame_to_signum(*ap); 176 177 if (signo < 0 || signo > NSIG) 178 error("%s: bad trap", *ap); 179 180 INTOFF; 181 if (action) 182 action = savestr(action); 183 184 if (trap[signo]) 185 ckfree(trap[signo]); 186 187 trap[signo] = action; 188 189 if (signo != 0) 190 setsignal(signo, 0); 191 INTON; 192 ap++; 193 } 194 return 0; 195 } 196 197 198 199 /* 200 * Clear traps on a fork or vfork. 201 * Takes one arg vfork, to tell it to not be destructive of 202 * the parents variables. 203 */ 204 205 void 206 clear_traps(int vforked) 207 { 208 char **tp; 209 210 for (tp = trap ; tp <= &trap[NSIG] ; tp++) { 211 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 212 INTOFF; 213 if (!vforked) { 214 ckfree(*tp); 215 *tp = NULL; 216 } 217 if (tp != &trap[0]) 218 setsignal(tp - trap, vforked); 219 INTON; 220 } 221 } 222 } 223 224 225 226 /* 227 * Set the signal handler for the specified signal. The routine figures 228 * out what it should be set to. 229 */ 230 231 long 232 setsignal(int signo, int vforked) 233 { 234 int action; 235 sig_t sigact = SIG_DFL; 236 struct sigaction act, oact; 237 char *t, tsig; 238 239 if ((t = trap[signo]) == NULL) 240 action = S_DFL; 241 else if (*t != '\0') 242 action = S_CATCH; 243 else 244 action = S_IGN; 245 if (rootshell && !vforked && action == S_DFL) { 246 switch (signo) { 247 case SIGINT: 248 if (iflag || minusc || sflag == 0) 249 action = S_CATCH; 250 break; 251 case SIGQUIT: 252 #ifdef DEBUG 253 if (debug) 254 break; 255 #endif 256 /* FALLTHROUGH */ 257 case SIGTERM: 258 if (iflag) 259 action = S_IGN; 260 break; 261 #if JOBS 262 case SIGTSTP: 263 case SIGTTOU: 264 if (mflag) 265 action = S_IGN; 266 break; 267 #endif 268 } 269 } 270 271 t = &sigmode[signo - 1]; 272 tsig = *t; 273 if (tsig == 0) { 274 /* 275 * current setting unknown 276 */ 277 if (!getsigaction(signo, &sigact)) { 278 /* 279 * Pretend it worked; maybe we should give a warning 280 * here, but other shells don't. We don't alter 281 * sigmode, so that we retry every time. 282 */ 283 return 0; 284 } 285 if (sigact == SIG_IGN) { 286 if (mflag && (signo == SIGTSTP || 287 signo == SIGTTIN || signo == SIGTTOU)) { 288 tsig = S_IGN; /* don't hard ignore these */ 289 } else 290 tsig = S_HARD_IGN; 291 } else { 292 tsig = S_RESET; /* force to be set */ 293 } 294 } 295 if (tsig == S_HARD_IGN || tsig == action) 296 return 0; 297 switch (action) { 298 case S_DFL: sigact = SIG_DFL; break; 299 case S_CATCH: sigact = onsig; break; 300 case S_IGN: sigact = SIG_IGN; break; 301 } 302 if (!vforked) 303 *t = action; 304 act.sa_handler = sigact; 305 sigemptyset(&act.sa_mask); 306 act.sa_flags = 0; 307 #ifdef SA_INTERRUPT 308 act.sa_flags |= SA_INTERRUPT; 309 #endif 310 if(sigaction(signo, &act, &oact) < 0) 311 return (long) SIG_ERR; 312 return (long) oact.sa_handler; 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 * Ignore a signal. 331 */ 332 333 void 334 ignoresig(int signo, int vforked) 335 { 336 if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) 337 bsd_signal(signo, SIG_IGN); 338 if (!vforked) 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(0); 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(int signo) 366 { 367 bsd_signal(signo, onsig); 368 if (signo == SIGINT && trap[SIGINT] == NULL) { 369 onint(); 370 return; 371 } 372 gotsig[signo - 1] = 1; 373 pendingsigs++; 374 } 375 376 377 378 /* 379 * Called to execute a trap. Perhaps we should avoid entering new trap 380 * handlers while we are executing a trap handler. 381 */ 382 383 void 384 dotrap(void) 385 { 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(int on) 414 { 415 static int is_interactive; 416 417 if (on == is_interactive) 418 return; 419 setsignal(SIGINT, 0); 420 setsignal(SIGQUIT, 0); 421 setsignal(SIGTERM, 0); 422 is_interactive = on; 423 } 424 425 426 427 /* 428 * Called to exit the shell. 429 */ 430 431 void 432 exitshell(int status) 433 { 434 struct jmploc loc1, loc2; 435 char *p; 436 437 TRACE(("pid %d, exitshell(%d)\n", getpid(), status)); 438 if (setjmp(loc1.loc)) { 439 goto l1; 440 } 441 if (setjmp(loc2.loc)) { 442 goto l2; 443 } 444 handler = &loc1; 445 if ((p = trap[0]) != NULL && *p != '\0') { 446 trap[0] = NULL; 447 evalstring(p, 0); 448 } 449 l1: handler = &loc2; /* probably unnecessary */ 450 flushall(); 451 #if JOBS 452 setjobctl(0); 453 #endif 454 l2: _exit(status); 455 /* NOTREACHED */ 456 } 457
