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 static const char *sys_signame[NSIG] = { 64 "Unused", 65 "HUP", "INT", "QUIT", "ILL", 66 "TRAP", "ABRT", "BUS", "FPE", 67 "KILL", "USR1", "SEGV", "USR2", 68 "PIPE", "ALRM", "TERM", 69 "Unknown", 70 "CHLD", 71 "CONT", "STOP", "TSTP", "TTIN", 72 "TTOU", "URG", "XCPU", "XFSZ", 73 "VTALRM", "PROF", "WINCH", "IO", 74 "PWR", "SYS" 75 }; 76 77 /* 78 * Sigmode records the current value of the signal handlers for the various 79 * modes. A value of zero means that the current handler is not known. 80 * S_HARD_IGN indicates that the signal was ignored on entry to the shell, 81 */ 82 83 #define S_DFL 1 /* default signal handling (SIG_DFL) */ 84 #define S_CATCH 2 /* signal is caught */ 85 #define S_IGN 3 /* signal is ignored (SIG_IGN) */ 86 #define S_HARD_IGN 4 /* signal is ignored permenantly */ 87 #define S_RESET 5 /* temporary - to reset a hard ignored sig */ 88 89 90 char *trap[NSIG+1]; /* trap handler commands */ 91 MKINIT char sigmode[NSIG]; /* current value of signal */ 92 char gotsig[NSIG]; /* indicates specified signal received */ 93 int pendingsigs; /* indicates some signal received */ 94 95 static int getsigaction(int, sig_t *); 96 97 /* 98 * return the signal number described by `p' (as a number or a name) 99 * or -1 if it isn't one 100 */ 101 102 static int 103 signame_to_signum(const char *p) 104 { 105 int i; 106 107 if (is_number(p)) 108 return number(p); 109 110 if (strcasecmp(p, "exit") == 0 ) 111 return 0; 112 113 if (strncasecmp(p, "sig", 3) == 0) 114 p += 3; 115 116 for (i = 0; i < NSIG; ++i) 117 if (strcasecmp (p, sys_signame[i]) == 0) 118 return i; 119 return -1; 120 } 121 122 /* 123 * Print a list of valid signal names 124 */ 125 static void 126 printsignals(void) 127 { 128 int n; 129 130 out1str("EXIT "); 131 132 for (n = 1; n < NSIG; n++) { 133 out1fmt("%s", sys_signame[n]); 134 if ((n == NSIG/2) || n == (NSIG - 1)) 135 out1str("\n"); 136 else 137 out1c(' '); 138 } 139 } 140 141 /* 142 * The trap builtin. 143 */ 144 145 int 146 trapcmd(int argc, char **argv) 147 { 148 char *action; 149 char **ap; 150 int signo; 151 152 if (argc <= 1) { 153 for (signo = 0 ; signo <= NSIG ; signo++) 154 if (trap[signo] != NULL) { 155 out1fmt("trap -- "); 156 print_quoted(trap[signo]); 157 out1fmt(" %s\n", 158 (signo) ? sys_signame[signo] : "EXIT"); 159 } 160 return 0; 161 } 162 ap = argv + 1; 163 164 action = NULL; 165 166 if (strcmp(*ap, "--") == 0) 167 if (*++ap == NULL) 168 return 0; 169 170 if (signame_to_signum(*ap) == -1) { 171 if ((*ap)[0] == '-') { 172 if ((*ap)[1] == '\0') 173 ap++; 174 else if ((*ap)[1] == 'l' && (*ap)[2] == '\0') { 175 printsignals(); 176 return 0; 177 } 178 else 179 error("bad option %s\n", *ap); 180 } 181 else 182 action = *ap++; 183 } 184 185 while (*ap) { 186 if (is_number(*ap)) 187 signo = number(*ap); 188 else 189 signo = signame_to_signum(*ap); 190 191 if (signo < 0 || signo > NSIG) 192 error("%s: bad trap", *ap); 193 194 INTOFF; 195 if (action) 196 action = savestr(action); 197 198 if (trap[signo]) 199 ckfree(trap[signo]); 200 201 trap[signo] = action; 202 203 if (signo != 0) 204 setsignal(signo, 0); 205 INTON; 206 ap++; 207 } 208 return 0; 209 } 210 211 212 213 /* 214 * Clear traps on a fork or vfork. 215 * Takes one arg vfork, to tell it to not be destructive of 216 * the parents variables. 217 */ 218 219 void 220 clear_traps(int vforked) 221 { 222 char **tp; 223 224 for (tp = trap ; tp <= &trap[NSIG] ; tp++) { 225 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 226 INTOFF; 227 if (!vforked) { 228 ckfree(*tp); 229 *tp = NULL; 230 } 231 if (tp != &trap[0]) 232 setsignal(tp - trap, vforked); 233 INTON; 234 } 235 } 236 } 237 238 239 240 /* 241 * Set the signal handler for the specified signal. The routine figures 242 * out what it should be set to. 243 */ 244 245 long 246 setsignal(int signo, int vforked) 247 { 248 int action; 249 sig_t sigact = SIG_DFL; 250 struct sigaction act, oact; 251 char *t, tsig; 252 253 if ((t = trap[signo]) == NULL) 254 action = S_DFL; 255 else if (*t != '\0') 256 action = S_CATCH; 257 else 258 action = S_IGN; 259 if (rootshell && !vforked && action == S_DFL) { 260 switch (signo) { 261 case SIGINT: 262 if (iflag || minusc || sflag == 0) 263 action = S_CATCH; 264 break; 265 case SIGQUIT: 266 #ifdef DEBUG 267 if (debug) 268 break; 269 #endif 270 /* FALLTHROUGH */ 271 case SIGTERM: 272 if (iflag) 273 action = S_IGN; 274 break; 275 #if JOBS 276 case SIGTSTP: 277 case SIGTTOU: 278 if (mflag) 279 action = S_IGN; 280 break; 281 #endif 282 } 283 } 284 285 t = &sigmode[signo - 1]; 286 tsig = *t; 287 if (tsig == 0) { 288 /* 289 * current setting unknown 290 */ 291 if (!getsigaction(signo, &sigact)) { 292 /* 293 * Pretend it worked; maybe we should give a warning 294 * here, but other shells don't. We don't alter 295 * sigmode, so that we retry every time. 296 */ 297 return 0; 298 } 299 if (sigact == SIG_IGN) { 300 if (mflag && (signo == SIGTSTP || 301 signo == SIGTTIN || signo == SIGTTOU)) { 302 tsig = S_IGN; /* don't hard ignore these */ 303 } else 304 tsig = S_HARD_IGN; 305 } else { 306 tsig = S_RESET; /* force to be set */ 307 } 308 } 309 if (tsig == S_HARD_IGN || tsig == action) 310 return 0; 311 switch (action) { 312 case S_DFL: sigact = SIG_DFL; break; 313 case S_CATCH: sigact = onsig; break; 314 case S_IGN: sigact = SIG_IGN; break; 315 } 316 if (!vforked) 317 *t = action; 318 act.sa_handler = sigact; 319 sigemptyset(&act.sa_mask); 320 act.sa_flags = 0; 321 #ifdef SA_INTERRUPT 322 act.sa_flags |= SA_INTERRUPT; 323 #endif 324 if(sigaction(signo, &act, &oact) < 0) 325 return (long) SIG_ERR; 326 return (long) oact.sa_handler; 327 } 328 329 /* 330 * Return the current setting for sig w/o changing it. 331 */ 332 static int 333 getsigaction(int signo, sig_t *sigact) 334 { 335 struct sigaction sa; 336 337 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 338 return 0; 339 *sigact = (sig_t) sa.sa_handler; 340 return 1; 341 } 342 343 /* 344 * Ignore a signal. 345 */ 346 347 void 348 ignoresig(int signo, int vforked) 349 { 350 if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) 351 bsd_signal(signo, SIG_IGN); 352 if (!vforked) 353 sigmode[signo - 1] = S_HARD_IGN; 354 } 355 356 357 #ifdef mkinit 358 INCLUDE <signal.h> 359 INCLUDE "trap.h" 360 361 SHELLPROC { 362 char *sm; 363 364 clear_traps(0); 365 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 366 if (*sm == S_IGN) 367 *sm = S_HARD_IGN; 368 } 369 } 370 #endif 371 372 373 374 /* 375 * Signal handler. 376 */ 377 378 void 379 onsig(int signo) 380 { 381 bsd_signal(signo, onsig); 382 if (signo == SIGINT && trap[SIGINT] == NULL) { 383 onint(); 384 return; 385 } 386 gotsig[signo - 1] = 1; 387 pendingsigs++; 388 } 389 390 391 392 /* 393 * Called to execute a trap. Perhaps we should avoid entering new trap 394 * handlers while we are executing a trap handler. 395 */ 396 397 void 398 dotrap(void) 399 { 400 int i; 401 int savestatus; 402 403 for (;;) { 404 for (i = 1 ; ; i++) { 405 if (gotsig[i - 1]) 406 break; 407 if (i >= NSIG) 408 goto done; 409 } 410 gotsig[i - 1] = 0; 411 savestatus=exitstatus; 412 evalstring(trap[i], 0); 413 exitstatus=savestatus; 414 } 415 done: 416 pendingsigs = 0; 417 } 418 419 420 421 /* 422 * Controls whether the shell is interactive or not. 423 */ 424 425 426 void 427 setinteractive(int on) 428 { 429 static int is_interactive; 430 431 if (on == is_interactive) 432 return; 433 setsignal(SIGINT, 0); 434 setsignal(SIGQUIT, 0); 435 setsignal(SIGTERM, 0); 436 is_interactive = on; 437 } 438 439 440 441 /* 442 * Called to exit the shell. 443 */ 444 445 void 446 exitshell(int status) 447 { 448 struct jmploc loc1, loc2; 449 char *p; 450 451 TRACE(("pid %d, exitshell(%d)\n", getpid(), status)); 452 if (setjmp(loc1.loc)) { 453 goto l1; 454 } 455 if (setjmp(loc2.loc)) { 456 goto l2; 457 } 458 handler = &loc1; 459 if ((p = trap[0]) != NULL && *p != '\0') { 460 trap[0] = NULL; 461 evalstring(p, 0); 462 } 463 l1: handler = &loc2; /* probably unnecessary */ 464 flushall(); 465 #if JOBS 466 setjobctl(0); 467 #endif 468 l2: _exit(status); 469 /* NOTREACHED */ 470 } 471