1 /* $NetBSD: trap.c,v 1.12 1995/03/21 09:10:25 cgd 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. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #ifndef lint 40 #if 0 41 static char sccsid[] = "@(#)trap.c 8.1 (Berkeley) 5/31/93"; 42 #else 43 static char rcsid[] = "$NetBSD: trap.c,v 1.12 1995/03/21 09:10:25 cgd Exp $"; 44 #endif 45 #endif /* not lint */ 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 "options.h" 53 #include "syntax.h" 54 #include "output.h" 55 #include "memalloc.h" 56 #include "error.h" 57 #include "trap.h" 58 #include "mystring.h" 59 #include <signal.h> 60 #include <unistd.h> 61 62 63 /* 64 * Sigmode records the current value of the signal handlers for the various 65 * modes. A value of zero means that the current handler is not known. 66 * S_HARD_IGN indicates that the signal was ignored on entry to the shell, 67 */ 68 69 #define S_DFL 1 /* default signal handling (SIG_DFL) */ 70 #define S_CATCH 2 /* signal is caught */ 71 #define S_IGN 3 /* signal is ignored (SIG_IGN) */ 72 #define S_HARD_IGN 4 /* signal is ignored permenantly */ 73 #define S_RESET 5 /* temporary - to reset a hard ignored sig */ 74 75 76 extern char nullstr[1]; /* null string */ 77 78 char *trap[NSIG+1]; /* trap handler commands */ 79 MKINIT char sigmode[NSIG]; /* current value of signal */ 80 char gotsig[NSIG]; /* indicates specified signal received */ 81 int pendingsigs; /* indicates some signal received */ 82 83 /* 84 * The trap builtin. 85 */ 86 87 int 88 trapcmd(argc, argv) 89 int argc; 90 char **argv; 91 { 92 char *action; 93 char **ap; 94 int signo; 95 96 if (argc <= 1) { 97 for (signo = 0 ; signo <= NSIG ; signo++) { 98 if (trap[signo] != NULL) 99 out1fmt("%d: %s\n", signo, trap[signo]); 100 } 101 return 0; 102 } 103 ap = argv + 1; 104 if (is_number(*ap)) 105 action = NULL; 106 else 107 action = *ap++; 108 while (*ap) { 109 if ((signo = number(*ap)) < 0 || signo > NSIG) 110 error("%s: bad trap", *ap); 111 INTOFF; 112 if (action) 113 action = savestr(action); 114 if (trap[signo]) 115 ckfree(trap[signo]); 116 trap[signo] = action; 117 if (signo != 0) 118 setsignal(signo); 119 INTON; 120 ap++; 121 } 122 return 0; 123 } 124 125 126 127 /* 128 * Clear traps on a fork. 129 */ 130 131 void 132 clear_traps() { 133 char **tp; 134 135 for (tp = trap ; tp <= &trap[NSIG] ; tp++) { 136 if (*tp && **tp) { /* trap not NULL or SIG_IGN */ 137 INTOFF; 138 ckfree(*tp); 139 *tp = NULL; 140 if (tp != &trap[0]) 141 setsignal(tp - trap); 142 INTON; 143 } 144 } 145 } 146 147 148 149 /* 150 * Set the signal handler for the specified signal. The routine figures 151 * out what it should be set to. 152 */ 153 154 long 155 setsignal(signo) 156 int signo; 157 { 158 int action; 159 sig_t sigact; 160 char *t; 161 extern void onsig(); 162 extern sig_t getsigaction(); 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 t = &sigmode[signo - 1]; 200 if (*t == 0) { 201 /* 202 * current setting unknown 203 */ 204 sigact = getsigaction(signo); 205 if (sigact == SIG_IGN) { 206 if (mflag && (signo == SIGTSTP || 207 signo == SIGTTIN || signo == SIGTTOU)) { 208 *t = S_IGN; /* don't hard ignore these */ 209 } else 210 *t = S_HARD_IGN; 211 } else { 212 *t = S_RESET; /* force to be set */ 213 } 214 } 215 if (*t == S_HARD_IGN || *t == action) 216 return 0; 217 switch (action) { 218 case S_DFL: sigact = SIG_DFL; break; 219 case S_CATCH: sigact = onsig; break; 220 case S_IGN: sigact = SIG_IGN; break; 221 } 222 *t = action; 223 return (long)signal(signo, sigact); 224 } 225 226 /* 227 * Return the current setting for sig w/o changing it. 228 */ 229 sig_t 230 getsigaction(signo) 231 int signo; 232 { 233 struct sigaction sa; 234 235 if (sigaction(signo, (struct sigaction *)0, &sa) == -1) 236 error("Sigaction system call failed"); 237 238 return sa.sa_handler; 239 } 240 241 /* 242 * Ignore a signal. 243 */ 244 245 void 246 ignoresig(signo) 247 int signo; 248 { 249 if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) { 250 signal(signo, SIG_IGN); 251 } 252 sigmode[signo - 1] = S_HARD_IGN; 253 } 254 255 256 #ifdef mkinit 257 INCLUDE <signal.h> 258 INCLUDE "trap.h" 259 260 SHELLPROC { 261 char *sm; 262 263 clear_traps(); 264 for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { 265 if (*sm == S_IGN) 266 *sm = S_HARD_IGN; 267 } 268 } 269 #endif 270 271 272 273 /* 274 * Signal handler. 275 */ 276 277 void 278 onsig(signo) 279 int signo; 280 { 281 signal(signo, onsig); 282 if (signo == SIGINT && trap[SIGINT] == NULL) { 283 onint(); 284 return; 285 } 286 gotsig[signo - 1] = 1; 287 pendingsigs++; 288 } 289 290 291 292 /* 293 * Called to execute a trap. Perhaps we should avoid entering new trap 294 * handlers while we are executing a trap handler. 295 */ 296 297 void 298 dotrap() { 299 int i; 300 int savestatus; 301 302 for (;;) { 303 for (i = 1 ; ; i++) { 304 if (gotsig[i - 1]) 305 break; 306 if (i >= NSIG) 307 goto done; 308 } 309 gotsig[i - 1] = 0; 310 savestatus=exitstatus; 311 evalstring(trap[i]); 312 exitstatus=savestatus; 313 } 314 done: 315 pendingsigs = 0; 316 } 317 318 319 320 /* 321 * Controls whether the shell is interactive or not. 322 */ 323 324 325 void 326 setinteractive(on) 327 int on; 328 { 329 static int is_interactive; 330 331 if (on == is_interactive) 332 return; 333 setsignal(SIGINT); 334 setsignal(SIGQUIT); 335 setsignal(SIGTERM); 336 is_interactive = on; 337 } 338 339 340 341 /* 342 * Called to exit the shell. 343 */ 344 345 void 346 exitshell(status) 347 int status; 348 { 349 struct jmploc loc1, loc2; 350 char *p; 351 352 TRACE(("exitshell(%d) pid=%d\n", status, getpid())); 353 if (setjmp(loc1.loc)) { 354 goto l1; 355 } 356 if (setjmp(loc2.loc)) { 357 goto l2; 358 } 359 handler = &loc1; 360 if ((p = trap[0]) != NULL && *p != '\0') { 361 trap[0] = NULL; 362 evalstring(p); 363 } 364 l1: handler = &loc2; /* probably unnecessary */ 365 flushall(); 366 #if JOBS 367 setjobctl(0); 368 #endif 369 l2: _exit(status); 370 } 371