| 1 | /* $NetBSD: trap.c,v 1.31 2005/01/11 19:38:57 christos Exp $ */
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| 2 |
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| 3 | /*-
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| 4 | * Copyright (c) 1991, 1993
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| 5 | * The Regents of the University of California. All rights reserved.
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| 6 | *
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| 7 | * This code is derived from software contributed to Berkeley by
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| 8 | * Kenneth Almquist.
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| 9 | *
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| 10 | * Redistribution and use in source and binary forms, with or without
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| 11 | * modification, are permitted provided that the following conditions
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| 12 | * are met:
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| 13 | * 1. Redistributions of source code must retain the above copyright
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| 14 | * notice, this list of conditions and the following disclaimer.
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| 15 | * 2. Redistributions in binary form must reproduce the above copyright
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| 16 | * notice, this list of conditions and the following disclaimer in the
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| 17 | * documentation and/or other materials provided with the distribution.
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| 18 | * 3. Neither the name of the University nor the names of its contributors
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| 19 | * may be used to endorse or promote products derived from this software
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| 20 | * without specific prior written permission.
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| 21 | *
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| 22 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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| 23 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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| 24 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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| 25 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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| 26 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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| 27 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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| 28 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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| 29 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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| 30 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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| 31 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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| 32 | * SUCH DAMAGE.
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| 33 | */
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| 34 |
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| 35 | #include <sys/cdefs.h>
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| 36 | #ifndef lint
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| 37 | #if 0
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| 38 | static char sccsid[] = "@(#)trap.c 8.5 (Berkeley) 6/5/95";
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| 39 | #else
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| 40 | __RCSID("$NetBSD: trap.c,v 1.31 2005/01/11 19:38:57 christos Exp $");
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| 41 | #endif
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| 42 | #endif /* not lint */
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| 43 |
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| 44 | #include <signal.h>
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| 45 | #include <unistd.h>
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| 46 | #include <stdlib.h>
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| 47 |
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| 48 | #include "shell.h"
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| 49 | #include "main.h"
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| 50 | #include "nodes.h" /* for other headers */
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| 51 | #include "eval.h"
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| 52 | #include "jobs.h"
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| 53 | #include "show.h"
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| 54 | #include "options.h"
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| 55 | #include "syntax.h"
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| 56 | #include "output.h"
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| 57 | #include "memalloc.h"
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| 58 | #include "error.h"
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| 59 | #include "trap.h"
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| 60 | #include "mystring.h"
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| 61 | #include "var.h"
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| 62 |
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| 63 |
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| 64 | /*
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| 65 | * Sigmode records the current value of the signal handlers for the various
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| 66 | * modes. A value of zero means that the current handler is not known.
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| 67 | * S_HARD_IGN indicates that the signal was ignored on entry to the shell,
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| 68 | */
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| 69 |
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| 70 | #define S_DFL 1 /* default signal handling (SIG_DFL) */
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| 71 | #define S_CATCH 2 /* signal is caught */
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| 72 | #define S_IGN 3 /* signal is ignored (SIG_IGN) */
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| 73 | #define S_HARD_IGN 4 /* signal is ignored permenantly */
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| 74 | #define S_RESET 5 /* temporary - to reset a hard ignored sig */
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| 75 |
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| 76 |
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| 77 | char *trap[NSIG+1]; /* trap handler commands */
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| 78 | MKINIT char sigmode[NSIG]; /* current value of signal */
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| 79 | char gotsig[NSIG]; /* indicates specified signal received */
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| 80 | int pendingsigs; /* indicates some signal received */
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| 81 |
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| 82 | static int getsigaction(int, sig_t *);
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| 83 |
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| 84 | /*
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| 85 | * return the signal number described by `p' (as a number or a name)
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| 86 | * or -1 if it isn't one
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| 87 | */
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| 88 |
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| 89 | static int
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| 90 | signame_to_signum(const char *p)
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| 91 | {
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| 92 | int i;
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| 93 |
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| 94 | if (is_number(p))
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| 95 | return number(p);
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| 96 |
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| 97 | if (strcasecmp(p, "exit") == 0 )
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| 98 | return 0;
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| 99 |
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| 100 | if (strncasecmp(p, "sig", 3) == 0)
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| 101 | p += 3;
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| 102 |
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| 103 | for (i = 0; i < NSIG; ++i)
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| 104 | if (strcasecmp (p, sys_signame[i]) == 0)
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| 105 | return i;
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| 106 | return -1;
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| 107 | }
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| 108 |
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| 109 | /*
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| 110 | * Print a list of valid signal names
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| 111 | */
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| 112 | static void
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| 113 | printsignals(void)
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| 114 | {
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| 115 | int n;
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| 116 |
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| 117 | out1str("EXIT ");
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| 118 |
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| 119 | for (n = 1; n < NSIG; n++) {
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| 120 | out1fmt("%s", sys_signame[n]);
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| 121 | if ((n == NSIG/2) || n == (NSIG - 1))
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| 122 | out1str("\n");
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| 123 | else
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| 124 | out1c(' ');
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| 125 | }
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| 126 | }
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| 127 |
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| 128 | /*
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| 129 | * The trap builtin.
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| 130 | */
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| 131 |
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| 132 | int
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| 133 | trapcmd(int argc, char **argv)
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| 134 | {
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| 135 | char *action;
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| 136 | char **ap;
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| 137 | int signo;
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| 138 |
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| 139 | if (argc <= 1) {
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| 140 | for (signo = 0 ; signo <= NSIG ; signo++)
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| 141 | if (trap[signo] != NULL) {
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| 142 | out1fmt("trap -- ");
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| 143 | print_quoted(trap[signo]);
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| 144 | out1fmt(" %s\n",
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| 145 | (signo) ? sys_signame[signo] : "EXIT");
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| 146 | }
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| 147 | return 0;
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| 148 | }
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| 149 | ap = argv + 1;
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| 150 |
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| 151 | action = NULL;
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| 152 |
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| 153 | if (strcmp(*ap, "--") == 0)
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| 154 | if (*++ap == NULL)
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| 155 | return 0;
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| 156 |
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| 157 | if (signame_to_signum(*ap) == -1) {
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| 158 | if ((*ap)[0] == '-') {
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| 159 | if ((*ap)[1] == '\0')
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| 160 | ap++;
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| 161 | else if ((*ap)[1] == 'l' && (*ap)[2] == '\0') {
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| 162 | printsignals();
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| 163 | return 0;
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| 164 | }
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| 165 | else
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| 166 | error("bad option %s\n", *ap);
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| 167 | }
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| 168 | else
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| 169 | action = *ap++;
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| 170 | }
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| 171 |
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| 172 | while (*ap) {
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| 173 | if (is_number(*ap))
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| 174 | signo = number(*ap);
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| 175 | else
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| 176 | signo = signame_to_signum(*ap);
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| 177 |
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| 178 | if (signo < 0 || signo > NSIG)
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| 179 | error("%s: bad trap", *ap);
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| 180 |
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| 181 | INTOFF;
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| 182 | if (action)
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| 183 | action = savestr(action);
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| 184 |
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| 185 | if (trap[signo])
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| 186 | ckfree(trap[signo]);
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| 187 |
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| 188 | trap[signo] = action;
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| 189 |
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| 190 | if (signo != 0)
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| 191 | setsignal(signo, 0);
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| 192 | INTON;
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| 193 | ap++;
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| 194 | }
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| 195 | return 0;
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| 196 | }
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| 197 |
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| 198 |
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| 199 |
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| 200 | /*
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| 201 | * Clear traps on a fork or vfork.
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| 202 | * Takes one arg vfork, to tell it to not be destructive of
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| 203 | * the parents variables.
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| 204 | */
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| 205 |
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| 206 | void
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| 207 | clear_traps(int vforked)
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| 208 | {
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| 209 | char **tp;
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| 210 |
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| 211 | for (tp = trap ; tp <= &trap[NSIG] ; tp++) {
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| 212 | if (*tp && **tp) { /* trap not NULL or SIG_IGN */
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| 213 | INTOFF;
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| 214 | if (!vforked) {
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| 215 | ckfree(*tp);
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| 216 | *tp = NULL;
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| 217 | }
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| 218 | if (tp != &trap[0])
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| 219 | setsignal(tp - trap, vforked);
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| 220 | INTON;
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| 221 | }
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| 222 | }
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| 223 | }
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| 224 |
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| 225 |
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| 226 |
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| 227 | /*
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| 228 | * Set the signal handler for the specified signal. The routine figures
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| 229 | * out what it should be set to.
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| 230 | */
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| 231 |
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| 232 | long
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| 233 | setsignal(int signo, int vforked)
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| 234 | {
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| 235 | int action;
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| 236 | sig_t sigact = SIG_DFL;
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| 237 | char *t, tsig;
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| 238 |
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| 239 | if ((t = trap[signo]) == NULL)
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| 240 | action = S_DFL;
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| 241 | else if (*t != '\0')
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| 242 | action = S_CATCH;
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| 243 | else
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| 244 | action = S_IGN;
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| 245 | if (rootshell && !vforked && action == S_DFL) {
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| 246 | switch (signo) {
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| 247 | case SIGINT:
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| 248 | if (iflag || minusc || sflag == 0)
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| 249 | action = S_CATCH;
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| 250 | break;
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| 251 | case SIGQUIT:
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| 252 | #ifdef DEBUG
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| 253 | if (debug)
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| 254 | break;
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| 255 | #endif
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| 256 | /* FALLTHROUGH */
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| 257 | case SIGTERM:
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| 258 | if (iflag)
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| 259 | action = S_IGN;
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| 260 | break;
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| 261 | #if JOBS
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| 262 | case SIGTSTP:
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| 263 | case SIGTTOU:
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| 264 | if (mflag)
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| 265 | action = S_IGN;
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| 266 | break;
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| 267 | #endif
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| 268 | }
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| 269 | }
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| 270 |
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| 271 | t = &sigmode[signo - 1];
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| 272 | tsig = *t;
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| 273 | if (tsig == 0) {
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| 274 | /*
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| 275 | * current setting unknown
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| 276 | */
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| 277 | if (!getsigaction(signo, &sigact)) {
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| 278 | /*
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| 279 | * Pretend it worked; maybe we should give a warning
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| 280 | * here, but other shells don't. We don't alter
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| 281 | * sigmode, so that we retry every time.
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| 282 | */
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| 283 | return 0;
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| 284 | }
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| 285 | if (sigact == SIG_IGN) {
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| 286 | if (mflag && (signo == SIGTSTP ||
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| 287 | signo == SIGTTIN || signo == SIGTTOU)) {
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| 288 | tsig = S_IGN; /* don't hard ignore these */
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| 289 | } else
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| 290 | tsig = S_HARD_IGN;
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| 291 | } else {
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| 292 | tsig = S_RESET; /* force to be set */
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| 293 | }
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| 294 | }
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| 295 | if (tsig == S_HARD_IGN || tsig == action)
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| 296 | return 0;
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| 297 | switch (action) {
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| 298 | case S_DFL: sigact = SIG_DFL; break;
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| 299 | case S_CATCH: sigact = onsig; break;
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| 300 | case S_IGN: sigact = SIG_IGN; break;
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| 301 | }
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| 302 | if (!vforked)
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| 303 | *t = action;
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| 304 | siginterrupt(signo, 1);
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| 305 | return (long)signal(signo, sigact);
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| 306 | }
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| 307 |
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| 308 | /*
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| 309 | * Return the current setting for sig w/o changing it.
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| 310 | */
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| 311 | static int
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| 312 | getsigaction(int signo, sig_t *sigact)
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| 313 | {
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| 314 | struct sigaction sa;
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| 315 |
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| 316 | if (sigaction(signo, (struct sigaction *)0, &sa) == -1)
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| 317 | return 0;
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| 318 | *sigact = (sig_t) sa.sa_handler;
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| 319 | return 1;
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| 320 | }
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| 321 |
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| 322 | /*
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| 323 | * Ignore a signal.
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| 324 | */
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| 325 |
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| 326 | void
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| 327 | ignoresig(int signo, int vforked)
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| 328 | {
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| 329 | if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
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| 330 | signal(signo, SIG_IGN);
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| 331 | }
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| 332 | if (!vforked)
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| 333 | sigmode[signo - 1] = S_HARD_IGN;
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| 334 | }
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| 335 |
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| 336 |
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| 337 | #ifdef mkinit
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| 338 | INCLUDE <signal.h>
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| 339 | INCLUDE "trap.h"
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| 340 |
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| 341 | SHELLPROC {
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| 342 | char *sm;
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| 343 |
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| 344 | clear_traps(0);
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| 345 | for (sm = sigmode ; sm < sigmode + NSIG ; sm++) {
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| 346 | if (*sm == S_IGN)
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| 347 | *sm = S_HARD_IGN;
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| 348 | }
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| 349 | }
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| 350 | #endif
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| 351 |
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| 352 |
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| 353 |
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| 354 | /*
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| 355 | * Signal handler.
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| 356 | */
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| 357 |
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| 358 | void
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| 359 | onsig(int signo)
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| 360 | {
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| 361 | signal(signo, onsig);
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| 362 | if (signo == SIGINT && trap[SIGINT] == NULL) {
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| 363 | onint();
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| 364 | return;
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| 365 | }
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| 366 | gotsig[signo - 1] = 1;
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| 367 | pendingsigs++;
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| 368 | }
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| 369 |
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| 370 |
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| 371 |
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| 372 | /*
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| 373 | * Called to execute a trap. Perhaps we should avoid entering new trap
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| 374 | * handlers while we are executing a trap handler.
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| 375 | */
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| 376 |
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| 377 | void
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| 378 | dotrap(void)
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| 379 | {
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| 380 | int i;
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| 381 | int savestatus;
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| 382 |
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| 383 | for (;;) {
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| 384 | for (i = 1 ; ; i++) {
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| 385 | if (gotsig[i - 1])
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| 386 | break;
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| 387 | if (i >= NSIG)
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| 388 | goto done;
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| 389 | }
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| 390 | gotsig[i - 1] = 0;
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| 391 | savestatus=exitstatus;
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| 392 | evalstring(trap[i], 0);
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| 393 | exitstatus=savestatus;
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| 394 | }
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| 395 | done:
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| 396 | pendingsigs = 0;
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| 397 | }
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| 398 |
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| 399 |
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| 400 |
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| 401 | /*
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| 402 | * Controls whether the shell is interactive or not.
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| 403 | */
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| 404 |
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| 405 |
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| 406 | void
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| 407 | setinteractive(int on)
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| 408 | {
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| 409 | static int is_interactive;
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| 410 |
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| 411 | if (on == is_interactive)
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| 412 | return;
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| 413 | setsignal(SIGINT, 0);
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| 414 | setsignal(SIGQUIT, 0);
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| 415 | setsignal(SIGTERM, 0);
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| 416 | is_interactive = on;
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| 417 | }
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| 418 |
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| 419 |
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| 420 |
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| 421 | /*
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| 422 | * Called to exit the shell.
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| 423 | */
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| 424 |
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| 425 | void
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| 426 | exitshell(int status)
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| 427 | {
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| 428 | struct jmploc loc1, loc2;
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| 429 | char *p;
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| 430 |
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| 431 | TRACE(("pid %d, exitshell(%d)\n", getpid(), status));
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| 432 | if (setjmp(loc1.loc)) {
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| 433 | goto l1;
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| 434 | }
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| 435 | if (setjmp(loc2.loc)) {
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| 436 | goto l2;
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| 437 | }
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| 438 | handler = &loc1;
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| 439 | if ((p = trap[0]) != NULL && *p != '\0') {
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| 440 | trap[0] = NULL;
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| 441 | evalstring(p, 0);
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| 442 | }
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| 443 | l1: handler = &loc2; /* probably unnecessary */
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| 444 | output_flushall();
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| 445 | #if JOBS
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| 446 | setjobctl(0);
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| 447 | #endif
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| 448 | l2: _exit(status);
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| 449 | /* NOTREACHED */
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| 450 | }
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