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 1.3 1995/05/30 00:07:23 rgrimes Exp $ 37 */ 38 39 #ifndef lint 40 static char 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 extern char nullstr[1]; /* null string */ 76 77 char *trap[NSIG+1]; /* trap handler commands */ 78 MKINIT char sigmode[NSIG]; /* current value of signal */ 79 char gotsig[NSIG]; /* indicates specified signal received */ 80 int pendingsigs; /* indicates some signal received */ 81 82 static int getsigaction __P((int, sig_t *)); 83 84 /* 85 * The trap builtin. 86 */ 87 88 int 89 trapcmd(argc, argv) 90 int argc; 91 char **argv; 92 { 93 char *action; 94 char **ap; 95 int signo; 96 97 if (argc <= 1) { 98 for (signo = 0 ; signo <= NSIG ; signo++) { 99 if (trap[signo] != NULL) 100 out1fmt("%d: %s\n", signo, trap[signo]); 101 } 102 return 0; 103 } 104 ap = argv + 1; 105 if (is_number(*ap)) 106 action = NULL; 107 else 108 action = *ap++; 109 while (*ap) { 110 if ((signo = number(*ap)) < 0 || signo > NSIG) 111 error("%s: bad trap", *ap); 112 INTOFF; 113 if (action) 114 action = savestr(action); 115 if (trap[signo]) 116 ckfree(trap[signo]); 117 trap[signo] = action; 118 if (signo != 0) 119 setsignal(signo); 120 INTON; 121 ap++; 122 } 123 return 0; 124 } 125 126 127 128 /* 129 * Clear traps on a fork. 130 */ 131 132 void 133 clear_traps() { 134 char **tp; 135 136 for (tp = trap ; tp <= &trap[NSIG] ; tp++) { 137 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 138 INTOFF; 139 ckfree(*tp); 140 *tp = NULL; 141 if (tp != &trap[0]) 142 setsignal(tp - trap); 143 INTON; 144 } 145 } 146 } 147 148 149 150 /* 151 * Set the signal handler for the specified signal. The routine figures 152 * out what it should be set to. 153 */ 154 155 long 156 setsignal(signo) 157 int signo; 158 { 159 int action; 160 sig_t sigact = SIG_DFL; 161 char *t; 162 extern void onsig(); 163 164 if ((t = trap[signo]) == NULL) 165 action = S_DFL; 166 else if (*t != '\0') 167 action = S_CATCH; 168 else 169 action = S_IGN; 170 if (rootshell && action == S_DFL) { 171 switch (signo) { 172 case SIGINT: 173 if (iflag) 174 action = S_CATCH; 175 break; 176 case SIGQUIT: 177 #ifdef DEBUG 178 { 179 extern int debug; 180 181 if (debug) 182 break; 183 } 184 #endif 185 /* FALLTHROUGH */ 186 case SIGTERM: 187 if (iflag) 188 action = S_IGN; 189 break; 190 #if JOBS 191 case SIGTSTP: 192 case SIGTTOU: 193 if (mflag) 194 action = S_IGN; 195 break; 196 #endif 197 } 198 } 199 200 t = &sigmode[signo - 1]; 201 if (*t == 0) { 202 /* 203 * current setting unknown 204 */ 205 if (!getsigaction(signo, &sigact)) { 206 /* 207 * Pretend it worked; maybe we should give a warning 208 * here, but other shells don't. We don't alter 209 * sigmode, so that we retry every time. 210 */ 211 return 0; 212 } 213 if (sigact == SIG_IGN) { 214 if (mflag && (signo == SIGTSTP || 215 signo == SIGTTIN || signo == SIGTTOU)) { 216 *t = S_IGN; /* don't hard ignore these */ 217 } else 218 *t = S_HARD_IGN; 219 } else { 220 *t = S_RESET; /* force to be set */ 221 } 222 } 223 if (*t == S_HARD_IGN || *t == action) 224 return 0; 225 switch (action) { 226 case S_DFL: sigact = SIG_DFL; break; 227 case S_CATCH: sigact = onsig; break; 228 case S_IGN: sigact = SIG_IGN; break; 229 } 230 *t = action; 231 return (long)signal(signo, sigact); 232 } 233 234 /* 235 * Return the current setting for sig w/o changing it. 236 */ 237 static int 238 getsigaction(signo, sigact) 239 int signo; 240 sig_t *sigact; 241 { 242 struct sigaction sa; 243 244 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 245 return 0; 246 *sigact = (sig_t) sa.sa_handler; 247 return 1; 248 } 249 250 /* 251 * Ignore a signal. 252 */ 253 254 void 255 ignoresig(signo) 256 int signo; 257 { 258 if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) { 259 signal(signo, SIG_IGN); 260 } 261 sigmode[signo - 1] = S_HARD_IGN; 262 } 263 264 265 #ifdef mkinit 266 INCLUDE <signal.h> 267 INCLUDE "trap.h" 268 269 SHELLPROC { 270 char *sm; 271 272 clear_traps(); 273 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 274 if (*sm == S_IGN) 275 *sm = S_HARD_IGN; 276 } 277 } 278 #endif 279 280 281 282 /* 283 * Signal handler. 284 */ 285 286 void 287 onsig(signo) 288 int signo; 289 { 290 signal(signo, onsig); 291 if (signo == SIGINT && trap[SIGINT] == NULL) { 292 onint(); 293 return; 294 } 295 gotsig[signo - 1] = 1; 296 pendingsigs++; 297 } 298 299 300 301 /* 302 * Called to execute a trap. Perhaps we should avoid entering new trap 303 * handlers while we are executing a trap handler. 304 */ 305 306 void 307 dotrap() { 308 int i; 309 int savestatus; 310 311 for (;;) { 312 for (i = 1 ; ; i++) { 313 if (gotsig[i - 1]) 314 break; 315 if (i >= NSIG) 316 goto done; 317 } 318 gotsig[i - 1] = 0; 319 savestatus=exitstatus; 320 evalstring(trap[i]); 321 exitstatus=savestatus; 322 } 323 done: 324 pendingsigs = 0; 325 } 326 327 328 329 /* 330 * Controls whether the shell is interactive or not. 331 */ 332 333 334 void 335 setinteractive(on) 336 int on; 337 { 338 static int is_interactive; 339 340 if (on == is_interactive) 341 return; 342 setsignal(SIGINT); 343 setsignal(SIGQUIT); 344 setsignal(SIGTERM); 345 is_interactive = on; 346 } 347 348 349 350 /* 351 * Called to exit the shell. 352 */ 353 354 void 355 exitshell(status) 356 int status; 357 { 358 struct jmploc loc1, loc2; 359 char *p; 360 361 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 362 if (setjmp(loc1.loc)) { 363 goto l1; 364 } 365 if (setjmp(loc2.loc)) { 366 goto l2; 367 } 368 handler = &loc1; 369 if ((p = trap[0]) != NULL && *p != '\0') { 370 trap[0] = NULL; 371 evalstring(p); 372 } 373 l1: handler = &loc2; /* probably unnecessary */ 374 flushall(); 375 #if JOBS 376 setjobctl(0); 377 #endif 378 l2: _exit(status); 379 } 380