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/*
* Copyright (c) 1987 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

#include <config.h>
#include <stdlib.h>
#include <string.h>

#if !defined(HAVE_SETENV) || !defined(HAVE_UNSETENV)

static char *__findenv(const char *name, int *offset);
extern char **environ;

/*
* __findenv --
* Returns pointer to value associated with name, if any, else NULL.
* Sets offset to be the offset of the name/value combination in the
* environmental array, for use by setenv(3) and unsetenv(3).
* Explicitly removes '=' in argument name.
*
* This routine *should* be a static; don't use it.
*/
static char *
__findenv(name, offset)
register const char *name;
int *offset;
{
register int len, i;
register const char *np;
register char **p, *cp;

if (name == NULL || environ == NULL)
return (NULL);
for (np = name; *np && *np != '='; ++np)
;
len = np - name;
for (p = environ; (cp = *p) != NULL; ++p) {
for (np = name, i = len; i && *cp; i--)
if (*cp++ != *np++)
break;
if (i == 0 && *cp++ == '=') {
*offset = p - environ;
return (cp);
}
}
return (NULL);
}

#ifndef HAVE_SETENV
/*
* setenv --
* Set the value of the environmental variable "name" to be
* "value". If rewrite is set, replace any current value.
*/
int
setenv(name, value, rewrite)
register const char *name;
register const char *value;
int rewrite;
{
static int alloced; /* if allocated space before */
register char *C;
int offset;
size_t l_value;

if (*value == '=') /* no `=' in value */
++value;
l_value = strlen(value);
if ((C = __findenv(name, &offset))) { /* find if already exists */
if (!rewrite)
return (0);
if (strlen(C) >= l_value) { /* old larger; copy over */
while ((*C++ = *value++))
;
return (0);
}
} else { /* create new slot */
register int cnt;
register char **P;

for (P = environ, cnt = 0; *P; ++P, ++cnt);
if (alloced) { /* just increase size */
P = (char **)realloc((void *)environ,
(size_t)(sizeof(char *) * (cnt + 2)));
if (!P)
return (-1);
environ = P;
}
else { /* get new space */
alloced = 1; /* copy old entries into it */
P = (char **)malloc((size_t)(sizeof(char *) *
(cnt + 2)));
if (!P)
return (-1);
memmove(P, environ, cnt * sizeof(char *));
environ = P;
}
environ[cnt + 1] = NULL;
offset = cnt;
}
for (C = (char *)name; *C && *C != '='; ++C); /* no `=' in name */
if (!(environ[offset] = /* name + `=' + value */
malloc((size_t)((int)(C - name) + l_value + 2))))
return (-1);
for (C = environ[offset]; (*C = *name++) && *C != '='; ++C)
;
for (*C++ = '='; (*C++ = *value++); )
;
return (0);
}
#endif /* HAVE_SETENV */

#ifndef HAVE_UNSETENV
/*
* unsetenv(name) --
* Delete environmental variable "name".
*/
void
unsetenv(name)
const char *name;
{
register char **P;
int offset;

while (__findenv(name, &offset)) /* if set multiple times */
for (P = &environ[offset];; ++P)
if (!(*P = *(P + 1)))
break;
}
#endif /* HAVE_UNSETENV */

#endif /* !defined(HAVE_SETENV) || !defined(HAVE_UNSETENV) */
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