| 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 | * %sccs.include.redist.c% |
| 9 | */ |
| 10 | |
| 11 | #ifndef lint |
| 12 | static char sccsid[] = "@(#)trap.c 8.3 (Berkeley) %G%"; |
| 13 | #endif /* not lint */ |
| 14 | |
| 15 | #include <signal.h> |
| 16 | #include <unistd.h> |
| 17 | #include <stdlib.h> |
| 18 | |
| 19 | #include "shell.h" |
| 20 | #include "main.h" |
| 21 | #include "nodes.h" /* for other headers */ |
| 22 | #include "eval.h" |
| 23 | #include "jobs.h" |
| 24 | #include "show.h" |
| 25 | #include "options.h" |
| 26 | #include "syntax.h" |
| 27 | #include "output.h" |
| 28 | #include "memalloc.h" |
| 29 | #include "error.h" |
| 30 | #include "trap.h" |
| 31 | #include "mystring.h" |
| 32 | |
| 33 | |
| 34 | /* |
| 35 | * Sigmode records the current value of the signal handlers for the various |
| 36 | * modes. A value of zero means that the current handler is not known. |
| 37 | * S_HARD_IGN indicates that the signal was ignored on entry to the shell, |
| 38 | */ |
| 39 | |
| 40 | #define S_DFL 1 /* default signal handling (SIG_DFL) */ |
| 41 | #define S_CATCH 2 /* signal is caught */ |
| 42 | #define S_IGN 3 /* signal is ignored (SIG_IGN) */ |
| 43 | #define S_HARD_IGN 4 /* signal is ignored permenantly */ |
| 44 | #define S_RESET 5 /* temporary - to reset a hard ignored sig */ |
| 45 | |
| 46 | |
| 47 | extern char nullstr[1]; /* null string */ |
| 48 | |
| 49 | char *trap[NSIG+1]; /* trap handler commands */ |
| 50 | MKINIT char sigmode[NSIG]; /* current value of signal */ |
| 51 | char gotsig[NSIG]; /* indicates specified signal received */ |
| 52 | int pendingsigs; /* indicates some signal received */ |
| 53 | |
| 54 | /* |
| 55 | * The trap builtin. |
| 56 | */ |
| 57 | |
| 58 | int |
| 59 | trapcmd(argc, argv) |
| 60 | int argc; |
| 61 | char **argv; |
| 62 | { |
| 63 | char *action; |
| 64 | char **ap; |
| 65 | int signo; |
| 66 | |
| 67 | if (argc <= 1) { |
| 68 | for (signo = 0 ; signo <= NSIG ; signo++) { |
| 69 | if (trap[signo] != NULL) |
| 70 | out1fmt("%d: %s\n", signo, trap[signo]); |
| 71 | } |
| 72 | return 0; |
| 73 | } |
| 74 | ap = argv + 1; |
| 75 | if (is_number(*ap)) |
| 76 | action = NULL; |
| 77 | else |
| 78 | action = *ap++; |
| 79 | while (*ap) { |
| 80 | if ((signo = number(*ap)) < 0 || signo > NSIG) |
| 81 | error("%s: bad trap", *ap); |
| 82 | INTOFF; |
| 83 | if (action) |
| 84 | action = savestr(action); |
| 85 | if (trap[signo]) |
| 86 | ckfree(trap[signo]); |
| 87 | trap[signo] = action; |
| 88 | if (signo != 0) |
| 89 | setsignal(signo); |
| 90 | INTON; |
| 91 | ap++; |
| 92 | } |
| 93 | return 0; |
| 94 | } |
| 95 | |
| 96 | |
| 97 | |
| 98 | /* |
| 99 | * Clear traps on a fork. |
| 100 | */ |
| 101 | |
| 102 | void |
| 103 | clear_traps() { |
| 104 | char **tp; |
| 105 | |
| 106 | for (tp = trap ; tp <= &trap[NSIG] ; tp++) { |
| 107 | if (*tp && **tp) { /* trap not NULL or SIG_IGN */ |
| 108 | INTOFF; |
| 109 | ckfree(*tp); |
| 110 | *tp = NULL; |
| 111 | if (tp != &trap[0]) |
| 112 | setsignal(tp - trap); |
| 113 | INTON; |
| 114 | } |
| 115 | } |
| 116 | } |
| 117 | |
| 118 | |
| 119 | |
| 120 | /* |
| 121 | * Set the signal handler for the specified signal. The routine figures |
| 122 | * out what it should be set to. |
| 123 | */ |
| 124 | |
| 125 | long |
| 126 | setsignal(signo) |
| 127 | int signo; |
| 128 | { |
| 129 | int action; |
| 130 | sig_t sigact = SIG_DFL; |
| 131 | char *t; |
| 132 | extern void onsig(); |
| 133 | extern sig_t getsigaction(); |
| 134 | |
| 135 | if ((t = trap[signo]) == NULL) |
| 136 | action = S_DFL; |
| 137 | else if (*t != '\0') |
| 138 | action = S_CATCH; |
| 139 | else |
| 140 | action = S_IGN; |
| 141 | if (rootshell && action == S_DFL) { |
| 142 | switch (signo) { |
| 143 | case SIGINT: |
| 144 | if (iflag) |
| 145 | action = S_CATCH; |
| 146 | break; |
| 147 | case SIGQUIT: |
| 148 | #ifdef DEBUG |
| 149 | { |
| 150 | extern int debug; |
| 151 | |
| 152 | if (debug) |
| 153 | break; |
| 154 | } |
| 155 | #endif |
| 156 | /* FALLTHROUGH */ |
| 157 | case SIGTERM: |
| 158 | if (iflag) |
| 159 | action = S_IGN; |
| 160 | break; |
| 161 | #if JOBS |
| 162 | case SIGTSTP: |
| 163 | case SIGTTOU: |
| 164 | if (mflag) |
| 165 | action = S_IGN; |
| 166 | break; |
| 167 | #endif |
| 168 | } |
| 169 | } |
| 170 | t = &sigmode[signo - 1]; |
| 171 | if (*t == 0) { |
| 172 | /* |
| 173 | * current setting unknown |
| 174 | */ |
| 175 | sigact = getsigaction(signo); |
| 176 | if (sigact == SIG_IGN) { |
| 177 | if (mflag && (signo == SIGTSTP || |
| 178 | signo == SIGTTIN || signo == SIGTTOU)) { |
| 179 | *t = S_IGN; /* don't hard ignore these */ |
| 180 | } else |
| 181 | *t = S_HARD_IGN; |
| 182 | } else { |
| 183 | *t = S_RESET; /* force to be set */ |
| 184 | } |
| 185 | } |
| 186 | if (*t == S_HARD_IGN || *t == action) |
| 187 | return 0; |
| 188 | switch (action) { |
| 189 | case S_DFL: sigact = SIG_DFL; break; |
| 190 | case S_CATCH: sigact = onsig; break; |
| 191 | case S_IGN: sigact = SIG_IGN; break; |
| 192 | } |
| 193 | *t = action; |
| 194 | return (long)signal(signo, sigact); |
| 195 | } |
| 196 | |
| 197 | /* |
| 198 | * Return the current setting for sig w/o changing it. |
| 199 | */ |
| 200 | sig_t |
| 201 | getsigaction(signo) |
| 202 | int signo; |
| 203 | { |
| 204 | struct sigaction sa; |
| 205 | |
| 206 | if (sigaction(signo, (struct sigaction *)0, &sa) == -1) |
| 207 | error("Sigaction system call failed"); |
| 208 | |
| 209 | return (sig_t) sa.sa_handler; |
| 210 | } |
| 211 | |
| 212 | /* |
| 213 | * Ignore a signal. |
| 214 | */ |
| 215 | |
| 216 | void |
| 217 | ignoresig(signo) |
| 218 | int signo; |
| 219 | { |
| 220 | if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) { |
| 221 | signal(signo, SIG_IGN); |
| 222 | } |
| 223 | sigmode[signo - 1] = S_HARD_IGN; |
| 224 | } |
| 225 | |
| 226 | |
| 227 | #ifdef mkinit |
| 228 | INCLUDE <signal.h> |
| 229 | INCLUDE "trap.h" |
| 230 | |
| 231 | SHELLPROC { |
| 232 | char *sm; |
| 233 | |
| 234 | clear_traps(); |
| 235 | for (sm = sigmode ; sm < sigmode + NSIG ; sm++) { |
| 236 | if (*sm == S_IGN) |
| 237 | *sm = S_HARD_IGN; |
| 238 | } |
| 239 | } |
| 240 | #endif |
| 241 | |
| 242 | |
| 243 | |
| 244 | /* |
| 245 | * Signal handler. |
| 246 | */ |
| 247 | |
| 248 | void |
| 249 | onsig(signo) |
| 250 | int signo; |
| 251 | { |
| 252 | signal(signo, onsig); |
| 253 | if (signo == SIGINT && trap[SIGINT] == NULL) { |
| 254 | onint(); |
| 255 | return; |
| 256 | } |
| 257 | gotsig[signo - 1] = 1; |
| 258 | pendingsigs++; |
| 259 | } |
| 260 | |
| 261 | |
| 262 | |
| 263 | /* |
| 264 | * Called to execute a trap. Perhaps we should avoid entering new trap |
| 265 | * handlers while we are executing a trap handler. |
| 266 | */ |
| 267 | |
| 268 | void |
| 269 | dotrap() { |
| 270 | int i; |
| 271 | int savestatus; |
| 272 | |
| 273 | for (;;) { |
| 274 | for (i = 1 ; ; i++) { |
| 275 | if (gotsig[i - 1]) |
| 276 | break; |
| 277 | if (i >= NSIG) |
| 278 | goto done; |
| 279 | } |
| 280 | gotsig[i - 1] = 0; |
| 281 | savestatus=exitstatus; |
| 282 | evalstring(trap[i]); |
| 283 | exitstatus=savestatus; |
| 284 | } |
| 285 | done: |
| 286 | pendingsigs = 0; |
| 287 | } |
| 288 | |
| 289 | |
| 290 | |
| 291 | /* |
| 292 | * Controls whether the shell is interactive or not. |
| 293 | */ |
| 294 | |
| 295 | |
| 296 | void |
| 297 | setinteractive(on) |
| 298 | int on; |
| 299 | { |
| 300 | static int is_interactive; |
| 301 | |
| 302 | if (on == is_interactive) |
| 303 | return; |
| 304 | setsignal(SIGINT); |
| 305 | setsignal(SIGQUIT); |
| 306 | setsignal(SIGTERM); |
| 307 | is_interactive = on; |
| 308 | } |
| 309 | |
| 310 | |
| 311 | |
| 312 | /* |
| 313 | * Called to exit the shell. |
| 314 | */ |
| 315 | |
| 316 | void |
| 317 | exitshell(status) |
| 318 | int status; |
| 319 | { |
| 320 | struct jmploc loc1, loc2; |
| 321 | char *p; |
| 322 | |
| 323 | TRACE(("exitshell(%d) pid=%d\n", status, getpid())); |
| 324 | if (setjmp(loc1.loc)) { |
| 325 | goto l1; |
| 326 | } |
| 327 | if (setjmp(loc2.loc)) { |
| 328 | goto l2; |
| 329 | } |
| 330 | handler = &loc1; |
| 331 | if ((p = trap[0]) != NULL && *p != '\0') { |
| 332 | trap[0] = NULL; |
| 333 | evalstring(p); |
| 334 | } |
| 335 | l1: handler = &loc2; /* probably unnecessary */ |
| 336 | flushall(); |
| 337 | #if JOBS |
| 338 | setjobctl(0); |
| 339 | #endif |
| 340 | l2: _exit(status); |
| 341 | } |