trap.c revision 90111
165532Snectar/*- 265532Snectar * Copyright (c) 1991, 1993 31573Srgrimes * The Regents of the University of California. All rights reserved. 41573Srgrimes * 51573Srgrimes * This code is derived from software contributed to Berkeley by 61573Srgrimes * Kenneth Almquist. 71573Srgrimes * 81573Srgrimes * Redistribution and use in source and binary forms, with or without 91573Srgrimes * modification, are permitted provided that the following conditions 101573Srgrimes * are met: 111573Srgrimes * 1. Redistributions of source code must retain the above copyright 121573Srgrimes * notice, this list of conditions and the following disclaimer. 131573Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 141573Srgrimes * notice, this list of conditions and the following disclaimer in the 151573Srgrimes * documentation and/or other materials provided with the distribution. 161573Srgrimes * 3. All advertising materials mentioning features or use of this software 171573Srgrimes * must display the following acknowledgement: 181573Srgrimes * This product includes software developed by the University of 191573Srgrimes * California, Berkeley and its contributors. 201573Srgrimes * 4. Neither the name of the University nor the names of its contributors 211573Srgrimes * may be used to endorse or promote products derived from this software 221573Srgrimes * without specific prior written permission. 231573Srgrimes * 241573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 251573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 261573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 271573Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 281573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 291573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 301573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31141580Sru * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 321573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 3365532Snectar * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 341573Srgrimes * SUCH DAMAGE. 3565532Snectar */ 361573Srgrimes 371573Srgrimes#ifndef lint 381573Srgrimes#if 0 391573Srgrimesstatic char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95"; 4065532Snectar#endif 4159460Sphantomstatic const char rcsid[] = 4259460Sphantom "$FreeBSD: head/bin/sh/trap.c 90111 2002-02-02 06:50:57Z imp $"; 431573Srgrimes#endif /* not lint */ 4484306Sru 451573Srgrimes#include <signal.h> 461573Srgrimes#include <unistd.h> 471573Srgrimes#include <stdlib.h> 481573Srgrimes 491573Srgrimes#include "shell.h" 501573Srgrimes#include "main.h" 511573Srgrimes#include "nodes.h" /* for other headers */ 521573Srgrimes#include "eval.h" 531573Srgrimes#include "jobs.h" 541573Srgrimes#include "show.h" 5565532Snectar#include "options.h" 5665532Snectar#include "syntax.h" 5765532Snectar#include "output.h" 5865532Snectar#include "memalloc.h" 591573Srgrimes#include "error.h" 601573Srgrimes#include "trap.h" 611573Srgrimes#include "mystring.h" 621573Srgrimes 631573Srgrimes 6465532Snectar/* 651573Srgrimes * Sigmode records the current value of the signal handlers for the various 661573Srgrimes * modes. A value of zero means that the current handler is not known. 671573Srgrimes * S_HARD_IGN indicates that the signal was ignored on entry to the shell, 681573Srgrimes */ 691573Srgrimes 701573Srgrimes#define S_DFL 1 /* default signal handling (SIG_DFL) */ 711573Srgrimes#define S_CATCH 2 /* signal is caught */ 721573Srgrimes#define S_IGN 3 /* signal is ignored (SIG_IGN) */ 731573Srgrimes#define S_HARD_IGN 4 /* signal is ignored permanently */ 741573Srgrimes#define S_RESET 5 /* temporary - to reset a hard ignored sig */ 751573Srgrimes 761573Srgrimes 771573SrgrimesMKINIT char sigmode[NSIG]; /* current value of signal */ 781573Srgrimesint pendingsigs; /* indicates some signal received */ 791573Srgrimesint in_dotrap; /* do we execute in a trap handler? */ 801573Srgrimesstatic char *volatile trap[NSIG]; /* trap handler commands */ 811573Srgrimesstatic volatile sig_atomic_t gotsig[NSIG]; 821573Srgrimes /* indicates specified signal received */ 831573Srgrimesstatic int ignore_sigchld; /* Used while handling SIGCHLD traps. */ 841573Srgrimes 8565532Snectarstatic int getsigaction(int, sig_t *); 861573Srgrimes 871573Srgrimes 881573Srgrimes/* 891573Srgrimes * Map a string to a signal number. 9067967Sasmodai */ 911573Srgrimesstatic int 921573Srgrimessigstring_to_signum(char *sig) 931573Srgrimes{ 941573Srgrimes 951573Srgrimes if (is_number(sig)) { 9668959Ssheldonh int signo; 9768959Ssheldonh 981573Srgrimes signo = atoi(sig); 991573Srgrimes return ((signo >= 0 && signo < NSIG) ? signo : (-1)); 100 } else if (strcasecmp(sig, "exit") == 0) { 101 return (0); 102 } else { 103 int n; 104 105 if (strncasecmp(sig, "sig", 3) == 0) 106 sig += 3; 107 for (n = 1; n < NSIG; n++) 108 if (strcasecmp(sys_signame[n], sig) == 0) 109 return (n); 110 } 111 return (-1); 112} 113 114 115/* 116 * Print a list of valid signal names. 117 */ 118static void 119printsignals(void) 120{ 121 int n; 122 123 for (n = 1; n < NSIG; n++) { 124 out1fmt("%s", sys_signame[n]); 125 if (n == (NSIG / 2) || n == (NSIG - 1)) 126 out1str("\n"); 127 else 128 out1c(' '); 129 } 130} 131 132 133/* 134 * The trap builtin. 135 */ 136int 137trapcmd(int argc, char **argv) 138{ 139 char *action; 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 action = NULL; 151 if (*++argv && strcmp(*argv, "--") == 0) 152 argv++; 153 if (*argv && sigstring_to_signum(*argv) == -1) { 154 if ((*argv)[0] != '-') { 155 action = *argv; 156 argv++; 157 } else if ((*argv)[1] == '\0') { 158 argv++; 159 } else if ((*argv)[1] == 'l' && (*argv)[2] == '\0') { 160 printsignals(); 161 return 0; 162 } else { 163 error("bad option %s", *argv); 164 } 165 } 166 while (*argv) { 167 if ((signo = sigstring_to_signum(*argv)) == -1) 168 error("bad signal %s", *argv); 169 INTOFF; 170 if (action) 171 action = savestr(action); 172 if (trap[signo]) 173 ckfree(trap[signo]); 174 trap[signo] = action; 175 if (signo != 0) 176 setsignal(signo); 177 INTON; 178 argv++; 179 } 180 return 0; 181} 182 183 184/* 185 * Clear traps on a fork. 186 */ 187void 188clear_traps(void) 189{ 190 char *volatile *tp; 191 192 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 193 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 194 INTOFF; 195 ckfree(*tp); 196 *tp = NULL; 197 if (tp != &trap[0]) 198 setsignal(tp - trap); 199 INTON; 200 } 201 } 202} 203 204 205/* 206 * Set the signal handler for the specified signal. The routine figures 207 * out what it should be set to. 208 */ 209void 210setsignal(int signo) 211{ 212 int action; 213 sig_t sig, sigact = SIG_DFL; 214 char *t; 215 216 if ((t = trap[signo]) == NULL) 217 action = S_DFL; 218 else if (*t != '\0') 219 action = S_CATCH; 220 else 221 action = S_IGN; 222 if (action == S_DFL) { 223 switch (signo) { 224 case SIGINT: 225 action = S_CATCH; 226 break; 227 case SIGQUIT: 228#ifdef DEBUG 229 { 230 extern int debug; 231 232 if (debug) 233 break; 234 } 235#endif 236 action = S_CATCH; 237 break; 238 case SIGTERM: 239 if (rootshell && iflag) 240 action = S_IGN; 241 break; 242#if JOBS 243 case SIGTSTP: 244 case SIGTTOU: 245 if (rootshell && mflag) 246 action = S_IGN; 247 break; 248#endif 249 } 250 } 251 252 t = &sigmode[signo]; 253 if (*t == 0) { 254 /* 255 * current setting unknown 256 */ 257 if (!getsigaction(signo, &sigact)) { 258 /* 259 * Pretend it worked; maybe we should give a warning 260 * here, but other shells don't. We don't alter 261 * sigmode, so that we retry every time. 262 */ 263 return; 264 } 265 if (sigact == SIG_IGN) { 266 if (mflag && (signo == SIGTSTP || 267 signo == SIGTTIN || signo == SIGTTOU)) { 268 *t = S_IGN; /* don't hard ignore these */ 269 } else 270 *t = S_HARD_IGN; 271 } else { 272 *t = S_RESET; /* force to be set */ 273 } 274 } 275 if (*t == S_HARD_IGN || *t == action) 276 return; 277 switch (action) { 278 case S_DFL: sigact = SIG_DFL; break; 279 case S_CATCH: sigact = onsig; break; 280 case S_IGN: sigact = SIG_IGN; break; 281 } 282 *t = action; 283 sig = signal(signo, sigact); 284#ifdef BSD 285 if (sig != SIG_ERR && action == S_CATCH) 286 siginterrupt(signo, 1); 287#endif 288} 289 290 291/* 292 * Return the current setting for sig w/o changing it. 293 */ 294static int 295getsigaction(int signo, sig_t *sigact) 296{ 297 struct sigaction sa; 298 299 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 300 return 0; 301 *sigact = (sig_t) sa.sa_handler; 302 return 1; 303} 304 305 306/* 307 * Ignore a signal. 308 */ 309void 310ignoresig(int signo) 311{ 312 313 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) { 314 signal(signo, SIG_IGN); 315 } 316 sigmode[signo] = S_HARD_IGN; 317} 318 319 320#ifdef mkinit 321INCLUDE <signal.h> 322INCLUDE "trap.h" 323 324SHELLPROC { 325 char *sm; 326 327 clear_traps(); 328 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 329 if (*sm == S_IGN) 330 *sm = S_HARD_IGN; 331 } 332} 333#endif 334 335 336/* 337 * Signal handler. 338 */ 339void 340onsig(int signo) 341{ 342 343#ifndef BSD 344 signal(signo, onsig); 345#endif 346 if (signo == SIGINT && trap[SIGINT] == NULL) { 347 onint(); 348 return; 349 } 350 351 if (signo != SIGCHLD || !ignore_sigchld) 352 gotsig[signo] = 1; 353 pendingsigs++; 354 355 /* If we are currently in a wait builtin, prepare to break it */ 356 if ((signo == SIGINT || signo == SIGQUIT) && in_waitcmd != 0) 357 breakwaitcmd = 1; 358 /* 359 * If a trap is set, not ignored and not the null command, we need 360 * to make sure traps are executed even when a child blocks signals. 361 */ 362 if (Tflag && 363 trap[signo] != NULL && 364 ! trap[signo][0] == '\0' && 365 ! (trap[signo][0] == ':' && trap[signo][1] == '\0')) 366 breakwaitcmd = 1; 367} 368 369 370/* 371 * Called to execute a trap. Perhaps we should avoid entering new trap 372 * handlers while we are executing a trap handler. 373 */ 374void 375dotrap(void) 376{ 377 int i; 378 int savestatus; 379 380 in_dotrap++; 381 for (;;) { 382 for (i = 1; i < NSIG; i++) { 383 if (gotsig[i]) { 384 gotsig[i] = 0; 385 if (trap[i]) { 386 /* 387 * Ignore SIGCHLD to avoid infinite recursion 388 * if the trap action does a fork. 389 */ 390 if (i == SIGCHLD) 391 ignore_sigchld++; 392 savestatus = exitstatus; 393 evalstring(trap[i]); 394 exitstatus = savestatus; 395 if (i == SIGCHLD) 396 ignore_sigchld--; 397 } 398 break; 399 } 400 } 401 if (i >= NSIG) 402 break; 403 } 404 in_dotrap--; 405 pendingsigs = 0; 406} 407 408 409/* 410 * Controls whether the shell is interactive or not. 411 */ 412void 413setinteractive(int on) 414{ 415 static int is_interactive = -1; 416 417 if (on == is_interactive) 418 return; 419 setsignal(SIGINT); 420 setsignal(SIGQUIT); 421 setsignal(SIGTERM); 422 is_interactive = on; 423} 424 425 426/* 427 * Called to exit the shell. 428 */ 429void 430exitshell(int status) 431{ 432 struct jmploc loc1, loc2; 433 char *p; 434 435 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 436 if (setjmp(loc1.loc)) { 437 goto l1; 438 } 439 if (setjmp(loc2.loc)) { 440 goto l2; 441 } 442 handler = &loc1; 443 if ((p = trap[0]) != NULL && *p != '\0') { 444 trap[0] = NULL; 445 evalstring(p); 446 } 447l1: handler = &loc2; /* probably unnecessary */ 448 flushall(); 449#if JOBS 450 setjobctl(0); 451#endif 452l2: _exit(status); 453} 454