ack/lang/cem/libcc.ansi/pure/stdlib/getenv.c

/*
 * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
 * See the copyright notice in the ACK home directory, in the file "Copyright".
 */
/* $Id$ */

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

extern char* _findenv(const char* name, int* offset);

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

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

/*
 * _findenv(name,offset) --
 *	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(register const char* name, int* offset)
{
	extern char** environ;
	register int len;
	register char** P;
	register const char* C;

	if (!environ)
		return NULL;

	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 (char*)(++C);
			}
	return (NULL);
}