| 1 | /*-
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| 2 | * Copyright (c) 1991 The Regents of the University of California.
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| 3 | * All rights reserved.
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| 4 | *
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| 5 | * This code is derived from software contributed to Berkeley by
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| 6 | * Kenneth Almquist.
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| 7 | *
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| 8 | * Redistribution and use in source and binary forms, with or without
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| 9 | * modification, are permitted provided that the following conditions
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| 10 | * are met:
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| 11 | * 1. Redistributions of source code must retain the above copyright
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| 12 | * notice, this list of conditions and the following disclaimer.
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| 13 | * 2. Redistributions in binary form must reproduce the above copyright
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| 14 | * notice, this list of conditions and the following disclaimer in the
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| 15 | * documentation and/or other materials provided with the distribution.
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| 16 | * 3. All advertising materials mentioning features or use of this software
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| 17 | * must display the following acknowledgement:
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| 18 | * This product includes software developed by the University of
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| 19 | * California, Berkeley and its contributors.
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| 20 | * 4. Neither the name of the University nor the names of its contributors
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| 21 | * may be used to endorse or promote products derived from this software
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| 22 | * without specific prior written permission.
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| 23 | *
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| 24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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| 25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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| 26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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| 27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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| 28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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| 29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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| 30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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| 31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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| 32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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| 33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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| 34 | * SUCH DAMAGE.
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| 35 | */
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| 36 |
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| 37 | #ifndef lint
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| 38 | static char sccsid[] = "@(#)trap.c 5.2 (Berkeley) 4/12/91";
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| 39 | #endif /* not lint */
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| 40 |
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| 41 | #include "shell.h"
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| 42 | #include "main.h"
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| 43 | #include "nodes.h" /* for other headers */
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| 44 | #include "eval.h"
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| 45 | #include "jobs.h"
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| 46 | #include "options.h"
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| 47 | #include "syntax.h"
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| 48 | #include "signames.h"
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| 49 | #include "output.h"
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| 50 | #include "memalloc.h"
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| 51 | #include "error.h"
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| 52 | #include "trap.h"
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| 53 | #include "mystring.h"
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| 54 | #include <sys/types.h>
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| 55 | #include <signal.h>
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| 56 |
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| 57 |
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| 58 | /*
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| 59 | * Sigmode records the current value of the signal handlers for the various
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| 60 | * modes. A value of zero means that the current handler is not known.
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| 61 | * S_HARD_IGN indicates that the signal was ignored on entry to the shell,
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| 62 | */
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| 63 |
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| 64 | #define S_DFL 1 /* default signal handling (SIG_DFL) */
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| 65 | #define S_CATCH 2 /* signal is caught */
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| 66 | #define S_IGN 3 /* signal is ignored (SIG_IGN) */
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| 67 | #define S_HARD_IGN 4 /* signal is ignored permenantly */
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| 68 |
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| 69 |
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| 70 | extern char nullstr[1]; /* null string */
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| 71 |
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| 72 | char *trap[MAXSIG+1]; /* trap handler commands */
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| 73 | MKINIT char sigmode[MAXSIG]; /* current value of signal */
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| 74 | char gotsig[MAXSIG]; /* indicates specified signal received */
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| 75 | int pendingsigs; /* indicates some signal received */
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| 76 |
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| 77 | /*
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| 78 | * The trap builtin.
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| 79 | */
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| 80 |
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| 81 | trapcmd(argc, argv) char **argv; {
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| 82 | char *action;
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| 83 | char **ap;
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| 84 | int signo;
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| 85 |
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| 86 | if (argc <= 1) {
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| 87 | for (signo = 0 ; signo <= MAXSIG ; signo++) {
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| 88 | if (trap[signo] != NULL)
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| 89 | out1fmt("%d: %s\n", signo, trap[signo]);
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| 90 | }
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| 91 | return 0;
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| 92 | }
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| 93 | ap = argv + 1;
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| 94 | if (is_number(*ap))
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| 95 | action = NULL;
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| 96 | else
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| 97 | action = *ap++;
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| 98 | while (*ap) {
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| 99 | if ((signo = number(*ap)) < 0 || signo > MAXSIG)
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| 100 | error("%s: bad trap", *ap);
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| 101 | INTOFF;
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| 102 | if (action)
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| 103 | action = savestr(action);
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| 104 | if (trap[signo])
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| 105 | ckfree(trap[signo]);
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| 106 | trap[signo] = action;
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| 107 | if (signo != 0)
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| 108 | setsignal(signo);
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| 109 | INTON;
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| 110 | ap++;
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| 111 | }
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| 112 | return 0;
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| 113 | }
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| 114 |
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| 115 |
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| 116 |
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| 117 | /*
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| 118 | * Clear traps on a fork.
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| 119 | */
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| 120 |
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| 121 | void
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| 122 | clear_traps() {
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| 123 | char **tp;
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| 124 |
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| 125 | for (tp = trap ; tp <= &trap[MAXSIG] ; tp++) {
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| 126 | if (*tp && **tp) { /* trap not NULL or SIG_IGN */
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| 127 | INTOFF;
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| 128 | ckfree(*tp);
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| 129 | *tp = NULL;
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| 130 | if (tp != &trap[0])
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| 131 | setsignal(tp - trap);
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| 132 | INTON;
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| 133 | }
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| 134 | }
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| 135 | }
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| 136 |
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| 137 |
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| 138 |
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| 139 | /*
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| 140 | * Set the signal handler for the specified signal. The routine figures
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| 141 | * out what it should be set to.
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| 142 | */
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| 143 |
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| 144 | int
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| 145 | setsignal(signo) {
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| 146 | int action;
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| 147 | sig_t sigact;
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| 148 | char *t;
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| 149 | extern void onsig();
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| 150 |
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| 151 | if ((t = trap[signo]) == NULL)
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| 152 | action = S_DFL;
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| 153 | else if (*t != '\0')
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| 154 | action = S_CATCH;
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| 155 | else
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| 156 | action = S_IGN;
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| 157 | if (rootshell && action == S_DFL) {
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| 158 | switch (signo) {
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| 159 | case SIGINT:
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| 160 | if (iflag)
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| 161 | action = S_CATCH;
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| 162 | break;
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| 163 | case SIGQUIT:
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| 164 | #if DEBUG
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| 165 | {
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| 166 | extern int debug;
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| 167 |
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| 168 | if (debug)
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| 169 | break;
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| 170 | }
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| 171 | #endif
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| 172 | /* FALLTHROUGH */
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| 173 | case SIGTERM:
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| 174 | if (iflag)
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| 175 | action = S_IGN;
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| 176 | break;
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| 177 | #if JOBS
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| 178 | case SIGTSTP:
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| 179 | case SIGTTOU:
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| 180 | if (jflag)
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| 181 | action = S_IGN;
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| 182 | break;
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| 183 | #endif
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| 184 | }
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| 185 | }
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| 186 | t = &sigmode[signo - 1];
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| 187 | if (*t == 0) { /* current setting unknown */
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| 188 | /*
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| 189 | * There is a race condition here if action is not S_IGN.
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| 190 | * A signal can be ignored that shouldn't be.
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| 191 | */
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| 192 | if ((int)(sigact = signal(signo, SIG_IGN)) == -1)
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| 193 | error("Signal system call failed");
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| 194 | if (sigact == SIG_IGN) {
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| 195 | *t = S_HARD_IGN;
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| 196 | } else {
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| 197 | *t = S_IGN;
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| 198 | }
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| 199 | }
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| 200 | if (*t == S_HARD_IGN || *t == action)
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| 201 | return 0;
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| 202 | switch (action) {
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| 203 | case S_DFL: sigact = SIG_DFL; break;
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| 204 | case S_CATCH: sigact = onsig; break;
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| 205 | case S_IGN: sigact = SIG_IGN; break;
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| 206 | }
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| 207 | *t = action;
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| 208 | return (int)signal(signo, sigact);
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| 209 | }
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| 210 |
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| 211 |
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| 212 | /*
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| 213 | * Ignore a signal.
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| 214 | */
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| 215 |
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| 216 | void
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| 217 | ignoresig(signo) {
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| 218 | if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
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| 219 | signal(signo, SIG_IGN);
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| 220 | }
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| 221 | sigmode[signo - 1] = S_HARD_IGN;
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| 222 | }
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| 223 |
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| 224 |
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| 225 | #ifdef mkinit
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| 226 | INCLUDE "signames.h"
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| 227 | INCLUDE "trap.h"
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| 228 |
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| 229 | SHELLPROC {
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| 230 | char *sm;
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| 231 |
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| 232 | clear_traps();
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| 233 | for (sm = sigmode ; sm < sigmode + MAXSIG ; sm++) {
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| 234 | if (*sm == S_IGN)
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| 235 | *sm = S_HARD_IGN;
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| 236 | }
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| 237 | }
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| 238 | #endif
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| 239 |
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| 240 |
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| 241 |
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| 242 | /*
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| 243 | * Signal handler.
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| 244 | */
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| 245 |
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| 246 | void
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| 247 | onsig(signo) {
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| 248 | signal(signo, onsig);
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| 249 | if (signo == SIGINT && trap[SIGINT] == NULL) {
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| 250 | onint();
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| 251 | return;
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| 252 | }
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| 253 | gotsig[signo - 1] = 1;
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| 254 | pendingsigs++;
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| 255 | }
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| 256 |
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| 257 |
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| 258 |
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| 259 | /*
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| 260 | * Called to execute a trap. Perhaps we should avoid entering new trap
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| 261 | * handlers while we are executing a trap handler.
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| 262 | */
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| 263 |
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| 264 | void
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| 265 | dotrap() {
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| 266 | int i;
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| 267 | int savestatus;
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| 268 |
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| 269 | for (;;) {
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| 270 | for (i = 1 ; ; i++) {
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| 271 | if (gotsig[i - 1])
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| 272 | break;
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| 273 | if (i >= MAXSIG)
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| 274 | goto done;
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| 275 | }
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| 276 | gotsig[i - 1] = 0;
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| 277 | savestatus=exitstatus;
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| 278 | evalstring(trap[i]);
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| 279 | exitstatus=savestatus;
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| 280 | }
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| 281 | done:
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| 282 | pendingsigs = 0;
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| 283 | }
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| 284 |
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| 285 |
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| 286 |
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| 287 | /*
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| 288 | * Controls whether the shell is interactive or not.
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| 289 | */
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| 290 |
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| 291 | int is_interactive;
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| 292 |
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| 293 | void
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| 294 | setinteractive(on) {
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| 295 | if (on == is_interactive)
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| 296 | return;
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| 297 | setsignal(SIGINT);
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| 298 | setsignal(SIGQUIT);
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| 299 | setsignal(SIGTERM);
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| 300 | is_interactive = on;
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| 301 | }
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| 302 |
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| 303 |
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| 304 |
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| 305 | /*
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| 306 | * Called to exit the shell.
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| 307 | */
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| 308 |
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| 309 | void
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| 310 | exitshell(status) {
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| 311 | struct jmploc loc1, loc2;
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| 312 | char *p;
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| 313 |
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| 314 | TRACE(("exitshell(%d) pid=%d\n", status, getpid()));
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| 315 | if (setjmp(loc1.loc)) goto l1;
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| 316 | if (setjmp(loc2.loc)) goto l2;
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| 317 | handler = &loc1;
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| 318 | if ((p = trap[0]) != NULL && *p != '\0') {
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| 319 | trap[0] = NULL;
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| 320 | evalstring(p);
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| 321 | }
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| 322 | l1: handler = &loc2; /* probably unnecessary */
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| 323 | flushall();
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| 324 | #if JOBS
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| 325 | setjobctl(0);
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| 326 | #endif
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| 327 | l2: _exit(status);
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| 328 | }
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