NetBSD/lib/libc/stdlib/getenv.c

106 lines
3.3 KiB
C

/* $NetBSD: getenv.c,v 1.14 1999/09/20 04:39:37 lukem Exp $ */
/*
* Copyright (c) 1987, 1993
* The 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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 <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)getenv.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: getenv.c,v 1.14 1999/09/20 04:39:37 lukem Exp $");
#endif
#endif /* LIBC_SCCS and not lint */
#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include "local.h"
#include "reentrant.h"
#ifdef _REENT
rwlock_t __environ_lock = RWLOCK_INITIALIZER;
#endif
/*
* getenv --
* Returns ptr to value associated with name, if any, else NULL.
*/
char *
getenv(name)
const char *name;
{
int offset;
char *result;
_DIAGASSERT(name != NULL);
rwlock_rdlock(&__environ_lock);
result = __findenv(name, &offset);
rwlock_unlock(&__environ_lock);
return (result);
}
/*
* __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.
*/
char *
__findenv(name, offset)
const char *name;
int *offset;
{
extern char **environ;
size_t len;
const char *np;
char **p, *c;
if (name == NULL || environ == NULL)
return (NULL);
for (np = name; *np && *np != '='; ++np)
continue;
len = np - name;
for (p = environ; (c = *p) != NULL; ++p)
if (strncmp(c, name, len) == 0 && c[len] == '=') {
*offset = p - environ;
return (c + len + 1);
}
return (NULL);
}