trap.c revision 199205
147Shannesw/*- 247Shannesw * Copyright (c) 1991, 1993 3877Sattila * The Regents of the University of California. All rights reserved. 447Shannesw * 547Shannesw * This code is derived from software contributed to Berkeley by 647Shannesw * Kenneth Almquist. 7877Sattila * 847Shannesw * Redistribution and use in source and binary forms, with or without 947Shannesw * modification, are permitted provided that the following conditions 10877Sattila * are met: 1147Shannesw * 1. Redistributions of source code must retain the above copyright 1247Shannesw * notice, this list of conditions and the following disclaimer. 1347Shannesw * 2. Redistributions in binary form must reproduce the above copyright 14877Sattila * notice, this list of conditions and the following disclaimer in the 1547Shannesw * documentation and/or other materials provided with the distribution. 1647Shannesw * 4. Neither the name of the University nor the names of its contributors 1747Shannesw * may be used to endorse or promote products derived from this software 18877Sattila * without specific prior written permission. 1947Shannesw * 2047Shannesw * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 2147Shannesw * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 2247Shannesw * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 2347Shannesw * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 2447Shannesw * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 2547Shannesw * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2647Shannesw * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2747Shannesw * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2847Shannesw * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2947Shannesw * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 3047Shannesw * SUCH DAMAGE. 3147Shannesw */ 3247Shannesw 3347Shannesw#ifndef lint 3447Shannesw#if 0 3547Shanneswstatic char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95"; 3647Shannesw#endif 3747Shannesw#endif /* not lint */ 3847Shannesw#include <sys/cdefs.h> 3947Shannesw__FBSDID("$FreeBSD: head/bin/sh/trap.c 199205 2009-11-11 23:13:24Z jilles $"); 4047Shannesw 4147Shannesw#include <signal.h> 4247Shannesw#include <unistd.h> 4347Shannesw#include <stdlib.h> 4447Shannesw 4547Shannesw#include "shell.h" 4647Shannesw#include "main.h" 4747Shannesw#include "nodes.h" /* for other headers */ 4847Shannesw#include "eval.h" 49819Slagergren#include "jobs.h" 5047Shannesw#include "show.h" 5147Shannesw#include "options.h" 5247Shannesw#include "syntax.h" 5347Shannesw#include "output.h" 5447Shannesw#include "memalloc.h" 55819Slagergren#include "error.h" 56819Slagergren#include "trap.h" 57819Slagergren#include "mystring.h" 58819Slagergren#include "myhistedit.h" 59819Slagergren 60819Slagergren 6147Shannesw/* 6247Shannesw * Sigmode records the current value of the signal handlers for the various 6347Shannesw * modes. A value of zero means that the current handler is not known. 6447Shannesw * S_HARD_IGN indicates that the signal was ignored on entry to the shell, 6547Shannesw */ 6647Shannesw 6747Shannesw#define S_DFL 1 /* default signal handling (SIG_DFL) */ 6847Shannesw#define S_CATCH 2 /* signal is caught */ 6947Shannesw#define S_IGN 3 /* signal is ignored (SIG_IGN) */ 7047Shannesw#define S_HARD_IGN 4 /* signal is ignored permanently */ 7147Shannesw#define S_RESET 5 /* temporary - to reset a hard ignored sig */ 7247Shannesw 7347Shannesw 7447ShanneswMKINIT char sigmode[NSIG]; /* current value of signal */ 7547Shanneswint pendingsigs; /* indicates some signal received */ 7647Shanneswint in_dotrap; /* do we execute in a trap handler? */ 7747Shanneswstatic char *volatile trap[NSIG]; /* trap handler commands */ 7847Shanneswstatic volatile sig_atomic_t gotsig[NSIG]; 7947Shannesw /* indicates specified signal received */ 8047Shanneswstatic int ignore_sigchld; /* Used while handling SIGCHLD traps. */ 8147Shanneswvolatile sig_atomic_t gotwinch; 8247Shannesw 8347Shanneswstatic int getsigaction(int, sig_t *); 8447Shannesw 8547Shannesw 8647Shannesw/* 8747Shannesw * Map a string to a signal number. 8847Shannesw * 8947Shannesw * Note: the signal number may exceed NSIG. 9047Shannesw */ 9147Shanneswstatic int 9247Shanneswsigstring_to_signum(char *sig) 9347Shannesw{ 9447Shannesw 9547Shannesw if (is_number(sig)) { 9647Shannesw int signo; 9747Shannesw 9847Shannesw signo = atoi(sig); 9947Shannesw return ((signo >= 0 && signo < NSIG) ? signo : (-1)); 10047Shannesw } else if (strcasecmp(sig, "exit") == 0) { 10147Shannesw return (0); 10247Shannesw } else { 10347Shannesw int n; 10447Shannesw 10547Shannesw if (strncasecmp(sig, "sig", 3) == 0) 10647Shannesw sig += 3; 10747Shannesw for (n = 1; n < sys_nsig; n++) 10847Shannesw if (sys_signame[n] && 10947Shannesw strcasecmp(sys_signame[n], sig) == 0) 11047Shannesw return (n); 11147Shannesw } 11247Shannesw return (-1); 11347Shannesw} 11447Shannesw 11547Shannesw 11647Shannesw/* 11747Shannesw * Print a list of valid signal names. 11847Shannesw */ 11947Shanneswstatic void 12047Shanneswprintsignals(void) 12147Shannesw{ 12247Shannesw int n, outlen; 12347Shannesw 12447Shannesw outlen = 0; 12547Shannesw for (n = 1; n < sys_nsig; n++) { 12647Shannesw if (sys_signame[n]) { 12747Shannesw out1fmt("%s", sys_signame[n]); 12847Shannesw outlen += strlen(sys_signame[n]); 12947Shannesw } else { 13047Shannesw out1fmt("%d", n); 13147Shannesw outlen += 3; /* good enough */ 13247Shannesw } 13347Shannesw ++outlen; 13447Shannesw if (outlen > 70 || n == sys_nsig - 1) { 13547Shannesw out1str("\n"); 13647Shannesw outlen = 0; 13747Shannesw } else { 13847Shannesw out1c(' '); 13947Shannesw } 14047Shannesw } 14147Shannesw} 14247Shannesw 14347Shannesw 14447Shannesw/* 14547Shannesw * The trap builtin. 14647Shannesw */ 14747Shanneswint 14847Shanneswtrapcmd(int argc, char **argv) 14947Shannesw{ 15047Shannesw char *action; 15147Shannesw int signo; 15247Shannesw 15347Shannesw if (argc <= 1) { 15447Shannesw for (signo = 0 ; signo < sys_nsig ; signo++) { 15547Shannesw if (signo < NSIG && trap[signo] != NULL) { 15647Shannesw out1str("trap -- "); 15747Shannesw out1qstr(trap[signo]); 15847Shannesw if (signo == 0) { 15947Shannesw out1str(" exit\n"); 16047Shannesw } else if (sys_signame[signo]) { 16147Shannesw out1fmt(" %s\n", sys_signame[signo]); 16247Shannesw } else { 16347Shannesw out1fmt(" %d\n", signo); 16447Shannesw } 16547Shannesw } 16647Shannesw } 16747Shannesw return 0; 16847Shannesw } 16947Shannesw action = NULL; 17047Shannesw if (*++argv && strcmp(*argv, "--") == 0) 17147Shannesw argv++; 17247Shannesw if (*argv && sigstring_to_signum(*argv) == -1) { 17347Shannesw if ((*argv)[0] != '-') { 17447Shannesw action = *argv; 17547Shannesw argv++; 17647Shannesw } else if ((*argv)[1] == '\0') { 17747Shannesw argv++; 17847Shannesw } else if ((*argv)[1] == 'l' && (*argv)[2] == '\0') { 17947Shannesw printsignals(); 18047Shannesw return 0; 18147Shannesw } else { 18247Shannesw error("bad option %s", *argv); 18347Shannesw } 18447Shannesw } 18547Shannesw while (*argv) { 186 if ((signo = sigstring_to_signum(*argv)) == -1) 187 error("bad signal %s", *argv); 188 INTOFF; 189 if (action) 190 action = savestr(action); 191 if (trap[signo]) 192 ckfree(trap[signo]); 193 trap[signo] = action; 194 if (signo != 0) 195 setsignal(signo); 196 INTON; 197 argv++; 198 } 199 return 0; 200} 201 202 203/* 204 * Clear traps on a fork. 205 */ 206void 207clear_traps(void) 208{ 209 char *volatile *tp; 210 211 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 212 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 213 INTOFF; 214 ckfree(*tp); 215 *tp = NULL; 216 if (tp != &trap[0]) 217 setsignal(tp - trap); 218 INTON; 219 } 220 } 221} 222 223 224/* 225 * Check if we have any traps enabled. 226 */ 227int 228have_traps(void) 229{ 230 char *volatile *tp; 231 232 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 233 if (*tp && **tp) /* trap not NULL or SIG_IGN */ 234 return 1; 235 } 236 return 0; 237} 238 239/* 240 * Set the signal handler for the specified signal. The routine figures 241 * out what it should be set to. 242 */ 243void 244setsignal(int signo) 245{ 246 int action; 247 sig_t sigact = SIG_DFL; 248 struct sigaction sa; 249 char *t; 250 251 if ((t = trap[signo]) == NULL) 252 action = S_DFL; 253 else if (*t != '\0') 254 action = S_CATCH; 255 else 256 action = S_IGN; 257 if (action == S_DFL) { 258 switch (signo) { 259 case SIGINT: 260 action = S_CATCH; 261 break; 262 case SIGQUIT: 263#ifdef DEBUG 264 { 265 extern int debug; 266 267 if (debug) 268 break; 269 } 270#endif 271 action = S_CATCH; 272 break; 273 case SIGTERM: 274 if (rootshell && iflag) 275 action = S_IGN; 276 break; 277#if JOBS 278 case SIGTSTP: 279 case SIGTTOU: 280 if (rootshell && mflag) 281 action = S_IGN; 282 break; 283#endif 284#ifndef NO_HISTORY 285 case SIGWINCH: 286 if (rootshell && iflag) 287 action = S_CATCH; 288 break; 289#endif 290 } 291 } 292 293 t = &sigmode[signo]; 294 if (*t == 0) { 295 /* 296 * current setting unknown 297 */ 298 if (!getsigaction(signo, &sigact)) { 299 /* 300 * Pretend it worked; maybe we should give a warning 301 * here, but other shells don't. We don't alter 302 * sigmode, so that we retry every time. 303 */ 304 return; 305 } 306 if (sigact == SIG_IGN) { 307 if (mflag && (signo == SIGTSTP || 308 signo == SIGTTIN || signo == SIGTTOU)) { 309 *t = S_IGN; /* don't hard ignore these */ 310 } else 311 *t = S_HARD_IGN; 312 } else { 313 *t = S_RESET; /* force to be set */ 314 } 315 } 316 if (*t == S_HARD_IGN || *t == action) 317 return; 318 switch (action) { 319 case S_DFL: sigact = SIG_DFL; break; 320 case S_CATCH: sigact = onsig; break; 321 case S_IGN: sigact = SIG_IGN; break; 322 } 323 *t = action; 324 sa.sa_handler = sigact; 325 sa.sa_flags = 0; 326 sigemptyset(&sa.sa_mask); 327 sigaction(signo, &sa, NULL); 328} 329 330 331/* 332 * Return the current setting for sig w/o changing it. 333 */ 334static int 335getsigaction(int signo, sig_t *sigact) 336{ 337 struct sigaction sa; 338 339 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 340 return 0; 341 *sigact = (sig_t) sa.sa_handler; 342 return 1; 343} 344 345 346/* 347 * Ignore a signal. 348 */ 349void 350ignoresig(int signo) 351{ 352 353 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) { 354 signal(signo, SIG_IGN); 355 } 356 sigmode[signo] = S_HARD_IGN; 357} 358 359 360#ifdef mkinit 361INCLUDE <signal.h> 362INCLUDE "trap.h" 363 364SHELLPROC { 365 char *sm; 366 367 clear_traps(); 368 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 369 if (*sm == S_IGN) 370 *sm = S_HARD_IGN; 371 } 372} 373#endif 374 375 376/* 377 * Signal handler. 378 */ 379void 380onsig(int signo) 381{ 382 383 if (signo == SIGINT && trap[SIGINT] == NULL) { 384 onint(); 385 return; 386 } 387 388 if (signo != SIGCHLD || !ignore_sigchld) 389 gotsig[signo] = 1; 390 pendingsigs++; 391 392 /* If we are currently in a wait builtin, prepare to break it */ 393 if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0) 394 breakwaitcmd = 1; 395 /* 396 * If a trap is set, not ignored and not the null command, we need 397 * to make sure traps are executed even when a child blocks signals. 398 */ 399 if (Tflag && 400 trap[signo] != NULL && 401 ! (trap[signo][0] == '\0') && 402 ! (trap[signo][0] == ':' && trap[signo][1] == '\0')) 403 breakwaitcmd = 1; 404 405#ifndef NO_HISTORY 406 if (signo == SIGWINCH) 407 gotwinch = 1; 408#endif 409} 410 411 412/* 413 * Called to execute a trap. Perhaps we should avoid entering new trap 414 * handlers while we are executing a trap handler. 415 */ 416void 417dotrap(void) 418{ 419 int i; 420 int savestatus; 421 422 in_dotrap++; 423 for (;;) { 424 for (i = 1; i < NSIG; i++) { 425 if (gotsig[i]) { 426 gotsig[i] = 0; 427 if (trap[i]) { 428 /* 429 * Ignore SIGCHLD to avoid infinite 430 * recursion if the trap action does 431 * a fork. 432 */ 433 if (i == SIGCHLD) 434 ignore_sigchld++; 435 savestatus = exitstatus; 436 evalstring(trap[i], 0); 437 exitstatus = savestatus; 438 if (i == SIGCHLD) 439 ignore_sigchld--; 440 } 441 break; 442 } 443 } 444 if (i >= NSIG) 445 break; 446 } 447 in_dotrap--; 448 pendingsigs = 0; 449} 450 451 452/* 453 * Controls whether the shell is interactive or not. 454 */ 455void 456setinteractive(int on) 457{ 458 static int is_interactive = -1; 459 460 if (on == is_interactive) 461 return; 462 setsignal(SIGINT); 463 setsignal(SIGQUIT); 464 setsignal(SIGTERM); 465#ifndef NO_HISTORY 466 setsignal(SIGWINCH); 467#endif 468 is_interactive = on; 469} 470 471 472/* 473 * Called to exit the shell. 474 */ 475void 476exitshell(int status) 477{ 478 struct jmploc loc1, loc2; 479 char *p; 480 481 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 482 if (setjmp(loc1.loc)) { 483 goto l1; 484 } 485 if (setjmp(loc2.loc)) { 486 goto l2; 487 } 488 handler = &loc1; 489 if ((p = trap[0]) != NULL && *p != '\0') { 490 trap[0] = NULL; 491 evalstring(p, 0); 492 } 493l1: handler = &loc2; /* probably unnecessary */ 494 flushall(); 495#if JOBS 496 setjobctl(0); 497#endif 498l2: _exit(status); 499} 500