1 /*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Kenneth Almquist. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * $Id: trap.c,v 1.5 1996/12/14 06:19:32 steve Exp $ 37 */ 38 39 #ifndef lint 40 static char const sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95"; 41 #endif /* not lint */ 42 43 #include <signal.h> 44 #include <unistd.h> 45 #include <stdlib.h> 46 47 #include "shell.h" 48 #include "main.h" 49 #include "nodes.h" /* for other headers */ 50 #include "eval.h" 51 #include "jobs.h" 52 #include "show.h" 53 #include "options.h" 54 #include "syntax.h" 55 #include "output.h" 56 #include "memalloc.h" 57 #include "error.h" 58 #include "trap.h" 59 #include "mystring.h" 60 61 62 /* 63 * Sigmode records the current value of the signal handlers for the various 64 * modes. A value of zero means that the current handler is not known. 65 * S_HARD_IGN indicates that the signal was ignored on entry to the shell, 66 */ 67 68 #define S_DFL 1 /* default signal handling (SIG_DFL) */ 69 #define S_CATCH 2 /* signal is caught */ 70 #define S_IGN 3 /* signal is ignored (SIG_IGN) */ 71 #define S_HARD_IGN 4 /* signal is ignored permenantly */ 72 #define S_RESET 5 /* temporary - to reset a hard ignored sig */ 73 74 75 MKINIT char sigmode[NSIG]; /* current value of signal */ 76 int pendingsigs; /* indicates some signal received */ 77 static char *trap[NSIG]; /* trap handler commands */ 78 static char gotsig[NSIG]; /* indicates specified signal received */ 79 static int ignore_sigchld; /* Used while handling SIGCHLD traps. */ 80 81 static int getsigaction __P((int, sig_t *)); 82 83 84 /* 85 * Map a string to a signal number. 86 */ 87 static int 88 sigstring_to_signum(sig) 89 char *sig; 90 { 91 92 if (is_number(sig)) { 93 int signo; 94 95 signo = atoi(sig); 96 return ((signo >= 0 && signo < NSIG) ? signo : (-1)); 97 } else if (strcasecmp(sig, "exit") == 0) { 98 return (0); 99 } else { 100 int n; 101 102 if (strncasecmp(sig, "sig", 3) == 0) 103 sig += 3; 104 for (n = 1; n < NSIG; n++) 105 if (strcasecmp(sys_signame[n], sig) == 0) 106 return (n); 107 } 108 return (-1); 109 } 110 111 112 /* 113 * Print a list of valid signal names. 114 */ 115 static void 116 printsignals() 117 { 118 int n; 119 120 for (n = 1; n < NSIG; n++) { 121 out1fmt("%s", sys_signame[n]); 122 if (n == (NSIG / 2) || n == (NSIG - 1)) 123 out1str("\n"); 124 else 125 out1c(' '); 126 } 127 } 128 129 130 /* 131 * The trap builtin. 132 */ 133 int 134 trapcmd(argc, argv) 135 int argc; 136 char **argv; 137 { 138 char *action; 139 int signo; 140 141 if (argc <= 1) { 142 for (signo = 0 ; signo < NSIG ; signo++) { 143 if (trap[signo] != NULL) 144 out1fmt("trap -- '%s' %s\n", trap[signo], 145 (signo) ? sys_signame[signo] : "exit"); 146 } 147 return 0; 148 } 149 action = NULL; 150 if (*++argv && strcmp(*argv, "--") == 0) 151 argv++; 152 if (*argv && sigstring_to_signum(*argv) == -1) { 153 if ((*argv)[0] != '-') { 154 action = *argv; 155 argv++; 156 } else if ((*argv)[1] == '\0') { 157 argv++; 158 } else if ((*argv)[1] == 'l' && (*argv)[2] == '\0') { 159 printsignals(); 160 return 0; 161 } else { 162 error("bad option %s", *argv); 163 } 164 } 165 while (*argv) { 166 if ((signo = sigstring_to_signum(*argv)) == -1) 167 error("bad signal %s", *argv); 168 INTOFF; 169 if (action) 170 action = savestr(action); 171 if (trap[signo]) 172 ckfree(trap[signo]); 173 trap[signo] = action; 174 if (signo != 0) 175 setsignal(signo); 176 INTON; 177 argv++; 178 } 179 return 0; 180 } 181 182 183 /* 184 * Clear traps on a fork. 185 */ 186 void 187 clear_traps() 188 { 189 char **tp; 190 191 for (tp = trap ; tp <= &trap[NSIG - 1] ; tp++) { 192 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 193 INTOFF; 194 ckfree(*tp); 195 *tp = NULL; 196 if (tp != &trap[0]) 197 setsignal(tp - trap); 198 INTON; 199 } 200 } 201 } 202 203 204 /* 205 * Set the signal handler for the specified signal. The routine figures 206 * out what it should be set to. 207 */ 208 long 209 setsignal(signo) 210 int signo; 211 { 212 int action; 213 sig_t 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 (rootshell && action == S_DFL) { 223 switch (signo) { 224 case SIGINT: 225 if (iflag) 226 action = S_CATCH; 227 break; 228 case SIGQUIT: 229 #ifdef DEBUG 230 { 231 extern int debug; 232 233 if (debug) 234 break; 235 } 236 #endif 237 /* FALLTHROUGH */ 238 case SIGTERM: 239 if (iflag) 240 action = S_IGN; 241 break; 242 #if JOBS 243 case SIGTSTP: 244 case SIGTTOU: 245 if (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 0; 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 0; 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 return (long)signal(signo, sigact); 284 } 285 286 287 /* 288 * Return the current setting for sig w/o changing it. 289 */ 290 static int 291 getsigaction(signo, sigact) 292 int signo; 293 sig_t *sigact; 294 { 295 struct sigaction sa; 296 297 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 298 return 0; 299 *sigact = (sig_t) sa.sa_handler; 300 return 1; 301 } 302 303 304 /* 305 * Ignore a signal. 306 */ 307 void 308 ignoresig(signo) 309 int signo; 310 { 311 312 if (sigmode[signo] != S_IGN && sigmode[signo] != S_HARD_IGN) { 313 signal(signo, SIG_IGN); 314 } 315 sigmode[signo] = S_HARD_IGN; 316 } 317 318 319 #ifdef mkinit 320 INCLUDE <signal.h> 321 INCLUDE "trap.h" 322 323 SHELLPROC { 324 char *sm; 325 326 clear_traps(); 327 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 328 if (*sm == S_IGN) 329 *sm = S_HARD_IGN; 330 } 331 } 332 #endif 333 334 335 /* 336 * Signal handler. 337 */ 338 void 339 onsig(signo) 340 int signo; 341 { 342 343 signal(signo, onsig); 344 if (signo == SIGINT && trap[SIGINT] == NULL) { 345 onint(); 346 return; 347 } 348 if (signo != SIGCHLD || !ignore_sigchld) 349 gotsig[signo] = 1; 350 pendingsigs++; 351 } 352 353 354 /* 355 * Called to execute a trap. Perhaps we should avoid entering new trap 356 * handlers while we are executing a trap handler. 357 */ 358 void 359 dotrap() 360 { 361 int i; 362 int savestatus; 363 364 for (;;) { 365 for (i = 1; i < NSIG; i++) { 366 if (gotsig[i]) { 367 gotsig[i] = 0; 368 if (trap[i]) { 369 /* 370 * Ignore SIGCHLD to avoid infinite recursion 371 * if the trap action does a fork. 372 */ 373 if (i == SIGCHLD) 374 ignore_sigchld++; 375 savestatus = exitstatus; 376 evalstring(trap[i]); 377 exitstatus = savestatus; 378 if (i == SIGCHLD) 379 ignore_sigchld--; 380 } 381 break; 382 } 383 } 384 if (i >= NSIG) 385 break; 386 } 387 pendingsigs = 0; 388 } 389 390 391 /* 392 * Controls whether the shell is interactive or not. 393 */ 394 void 395 setinteractive(on) 396 int on; 397 { 398 static int is_interactive = 0; 399 400 if (on == is_interactive) 401 return; 402 setsignal(SIGINT); 403 setsignal(SIGQUIT); 404 setsignal(SIGTERM); 405 is_interactive = on; 406 } 407 408 409 /* 410 * Called to exit the shell. 411 */ 412 void 413 exitshell(status) 414 int status; 415 { 416 struct jmploc loc1, loc2; 417 char *p; 418 419 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 420 if (setjmp(loc1.loc)) { 421 goto l1; 422 } 423 if (setjmp(loc2.loc)) { 424 goto l2; 425 } 426 handler = &loc1; 427 if ((p = trap[0]) != NULL && *p != '\0') { 428 trap[0] = NULL; 429 evalstring(p); 430 } 431 l1: handler = &loc2; /* probably unnecessary */ 432 flushall(); 433 #if JOBS 434 setjobctl(0); 435 #endif 436 l2: _exit(status); 437 } 438