152 lines
4.3 KiB
C
152 lines
4.3 KiB
C
/*
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* Provide setenv() and unsetenv() on platforms that don't have them.
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* From FreeBSD's libc.
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*/
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/*
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* Copyright (c) 1987, 1993
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* The Regents of the University of California. 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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 THE REGENTS 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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/* $XFree86$ */
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#include <stdlib.h>
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#include <stddef.h>
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#include <string.h>
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extern char **environ;
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extern int setenv(const char *name, const char *value, int overwrite);
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extern void unsetenv(const char *name);
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static char *
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findenv(const char *name, int *offset)
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{
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int len, i;
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const char *np;
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char **p, *cp;
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if (name == NULL || environ == NULL)
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return NULL;
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for (np = name; *np && *np != '='; ++np)
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continue;
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len = np - name;
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for (p = environ; (cp = *p) != NULL; ++p) {
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for (np = name, i = len; i && *cp; i--)
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if (*cp++ != *np++)
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break;
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if (i == 0 && *cp++ == '=') {
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*offset = p - environ;
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return cp;
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}
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}
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return NULL;
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}
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/*
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* setenv --
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* Set the value of the environmental variable "name" to be
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* "value". If overwrite is set, replace any current value.
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*/
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int
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setenv(const char *name, const char *value, int overwrite)
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{
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static char **alloced; /* if allocated space before */
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char *c;
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int l_value, offset;
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if (*value == '=') /* no '=' in value */
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++value;
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l_value = strlen(value);
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if ((c = findenv(name, &offset))) { /* find if already exists */
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if (!overwrite)
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return 0;
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if (strlen(c) >= l_value) { /* old larger; copy over */
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while ((*c++ = *value++))
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;
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return 0;
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}
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} else { /* create new slot */
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int cnt;
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char **p;
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for (p = environ, cnt = 0; *p; ++p, ++cnt)
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;
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if (alloced == environ) { /* just increase size */
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p = (char **)realloc((char *)environ,
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sizeof(char *) * (cnt + 2));
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if (!p)
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return -1;
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alloced = environ = p;
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} else { /* get new space */
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/* copy old entries into it */
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p = malloc(sizeof(char *) * (cnt + 2));
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if (!p)
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return -1;
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memcpy(p, environ, cnt * sizeof(char *));
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alloced = environ = p;
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}
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environ[cnt + 1] = NULL;
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offset = cnt;
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}
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for (c = (char *)name; *c && *c != '='; ++c) /* no '=' in name */
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;
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if (!(environ[offset] = /* name + '=' + value */
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malloc((int)(c - name) + l_value + 2)))
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return -1;
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for (c = environ[offset]; (*c = *name++) && *c != '='; ++c)
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;
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for (*c++ = '='; (*c++ = *value++); )
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;
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return 0;
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}
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/*
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* unsetenv(name) --
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* Delete environmental variable "name".
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*/
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void
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unsetenv(const char *name)
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{
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char **p;
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int offset;
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while (findenv(name, &offset)) /* if set multiple times */
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for (p = &environ[offset];; ++p)
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if (!(*p = *(p + 1)))
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break;
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}
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