/*
 * 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.
 */

/* based on @(#)setenv.c        8.1 (Berkeley) 6/4/93 */
/* based on @(#)getenv.c        8.1 (Berkeley) 6/4/93 */

#ifndef __STDC__
#define const
#endif

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

#ifndef __P
#define __P(x)  ()
#endif
static char *__findenv __P((const char *, int *));

/*
 * setenv --
 *      Set the value of the environmental variable "name" to be
 *      "value".  If rewrite is set, replace any current value.
 */
int
krb5_setenv(name, value, rewrite)
        register const char *name;
        register const char *value;
        int rewrite;
{
#if HAVE_SETENV
    return (setenv(name, value, rewrite));
#else
        extern char **environ;
        static int alloced;                     /* if allocated space before */
        register char *c;
        int l_value, offset;

        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 */
                        environ = (char **)realloc((char *)environ,
                            (size_t)(sizeof(char *) * (cnt + 2)));
                        if (!environ)
                                return (-1);
                }
                else {                          /* get new space */
                        alloced = 1;            /* copy old entries into it */
                        p = (char **)malloc((size_t)(sizeof(char *) * (cnt + 2)));
                        if (!p)
                                return (-1);
                        memcpy(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);
        /* LINTED */
        for (c = environ[offset]; (*c = *name++) && (*c != '='); ++c);
        for (*c++ = '='; (*c++ = *value++););
        return (0);
#endif
}

/*
 * unsetenv(name) --
 *      Delete environmental variable "name".
 */
void
krb5_unsetenv(name)
        const char *name;
{
#if HAVE_UNSETENV
    unsetenv(name);
#else
        extern char **environ;
        register char **p;
        int offset;

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

/*
 * getenv --
 *      Returns ptr to value associated with name, if any, else NULL.
 */
char *
krb5_getenv(name)
        const char *name;
{
#if HAVE_GETENV
    return (getenv(name));
#else
        int offset;

        return (__findenv(name, &offset));
#endif
}

#if (!HAVE_GETENV || !HAVE_SETENV || !HAVE_UNSETENV)
/*
 * __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.
 */
static char *
__findenv(name, offset)
        register const char *name;
        int *offset;
{
        extern char **environ;
        register int len;
        register const char *np;
        register 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);
}
#endif