Home | History | Annotate | Line # | Download | only in stdlib
getenv.c revision 1.1.1.2 
      1 /*
      2  * Copyright (c) 1987, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #if defined(LIBC_SCCS) && !defined(lint)
     35 static char sccsid[] = "@(#)getenv.c	8.1 (Berkeley) 6/4/93";
     36 #endif /* LIBC_SCCS and not lint */
     37 
     38 #include <stdlib.h>
     39 #include <stddef.h>
     40 #include <string.h>
     41 
     42 char *__findenv __P((const char *, int *));
     43 
     44 /*
     45  * getenv --
     46  *	Returns ptr to value associated with name, if any, else NULL.
     47  */
     48 char *
     49 getenv(name)
     50 	const char *name;
     51 {
     52 	int offset;
     53 
     54 	return (__findenv(name, &offset));
     55 }
     56 
     57 /*
     58  * __findenv --
     59  *	Returns pointer to value associated with name, if any, else NULL.
     60  *	Sets offset to be the offset of the name/value combination in the
     61  *	environmental array, for use by setenv(3) and unsetenv(3).
     62  *	Explicitly removes '=' in argument name.
     63  *
     64  *	This routine *should* be a static; don't use it.
     65  */
     66 char *
     67 __findenv(name, offset)
     68 	register const char *name;
     69 	int *offset;
     70 {
     71 	extern char **environ;
     72 	register int len;
     73 	register const char *np;
     74 	register char **p, *c;
     75 
     76 	if (name == NULL || environ == NULL)
     77 		return (NULL);
     78 	for (np = name; *np && *np != '='; ++np)
     79 		continue;
     80 	len = np - name;
     81 	for (p = environ; (c = *p) != NULL; ++p)
     82 		if (strncmp(c, name, len) == 0 && c[len] == '=') {
     83 			*offset = p - environ;
     84 			return (c + len + 1);
     85 		}
     86 	return (NULL);
     87 }
     88