118 lines
2.9 KiB
C
118 lines
2.9 KiB
C
/*-
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* Copyright (c) 2016 Stephen Heumann
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <stdlib.h>
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#include <string.h>
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extern char **environ;
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/*
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* UNSETENV_REORDERS_ENVIRON must be set to 1 if unsetenv() may
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* change entries in environ _prior to_ the one being removed.
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* The implementation in GNO 2.0.6's libc doesn't do this,
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* which allows us to optimize things a bit.
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*/
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#ifdef __GNO__
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# define UNSETENV_REORDERS_ENVIRON 0
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#else
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# define UNSETENV_REORDERS_ENVIRON 1
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#endif
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/*
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* Remove all environment entries except those indicated by retain,
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* which is a null-terminated list of environment variable names.
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*/
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int cleanenv(const char *const retain[])
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{
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int index = 0;
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const char *entry;
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const char *const *keep;
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while ((entry = environ[index]) != NULL) {
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char *equals = strchr(entry, '=');
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char *name;
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if (equals) {
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int match = 0;
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size_t len = equals - entry + 1;
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name = malloc(len);
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if (name == NULL)
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return -1;
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strncpy(name, entry, len-1);
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name[len-1] = 0;
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for (keep = retain; *keep != NULL; keep++) {
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if (strcmp(*keep, name) == 0) {
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match = 1;
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break;
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}
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}
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if (match) {
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index++;
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free(name);
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continue;
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}
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} else {
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name = strdup(entry);
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if (name == NULL)
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return -1;
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}
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unsetenv(name);
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free(name);
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#if UNSETENV_REORDERS_ENVIRON
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index = 0;
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#endif
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}
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return 0;
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}
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#ifdef DEBUG_CLEANENV
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#include <stdio.h>
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void dump_env(const char *s)
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{
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int index;
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const char *entry;
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puts(s);
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for (index = 0; (entry = environ[index]) != NULL; index++) {
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puts(entry);
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}
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}
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int main(void)
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{
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const char *retain[] = {"TERM", "USER", "PATH", "FOO", NULL};
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dump_env("Before:");
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cleanenv(retain);
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dump_env("\nAfter:");
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}
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#endif
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