BSD 4_3_Net_2 release

[unix-history] / usr / src / lib / libc / stdlib / getenv.c

/*
* 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. 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.
*/

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)getenv.c    5.8 (Berkeley) 2/23/91";
#endif /* LIBC_SCCS and not lint */

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

/*
* getenv --
*      Returns ptr to value associated with name, if any, else NULL.
*/
char *
getenv(name)
       const char *name;
{
       int offset;
       char *_findenv();

       return(_findenv(name, &offset));
}

/*
* _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)
       register char *name;
       int *offset;
{
       extern char **environ;
       register int len;
       register char **P, *C;

       for (C = name, len = 0; *C && *C != '='; ++C, ++len);
       for (P = environ; *P; ++P)
               if (!strncmp(*P, name, len))
                       if (*(C = *P + len) == '=') {
                               *offset = P - environ;
                               return(++C);
                       }
       return(NULL);
}