/*      $OpenBSD: setenv.c,v 1.20 2022/08/08 22:40:03 millert Exp $ */
/*
 * 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. 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 <errno.h>
#include <stdlib.h>
#include <string.h>

static char **lastenv;                          /* last value of environ */

/*
 * putenv --
 *      Add a name=value string directly to the environmental, replacing
 *      any current value.
 */
int
putenv(char *str)
{
        char **P, *cp;
        size_t cnt = 0;
        int offset = 0;

        for (cp = str; *cp && *cp != '='; ++cp)
                ;
        if (cp == str || *cp != '=') {
                /* '=' is the first character of string or is missing. */
                errno = EINVAL;
                return (-1);
        }

        if (__findenv(str, (int)(cp - str), &offset) != NULL) {
                environ[offset++] = str;
                /* could be set multiple times */
                while (__findenv(str, (int)(cp - str), &offset)) {
                        for (P = &environ[offset];; ++P)
                                if (!(*P = *(P + 1)))
                                        break;
                }
                return (0);
        }

        /* create new slot for string */
        if (environ != NULL) {
                for (P = environ; *P != NULL; P++)
                        ;
                cnt = P - environ;
        }
        P = reallocarray(lastenv, cnt + 2, sizeof(char *));
        if (!P)
                return (-1);
        if (lastenv != environ && environ != NULL)
                memcpy(P, environ, cnt * sizeof(char *));
        lastenv = environ = P;
        environ[cnt] = str;
        environ[cnt + 1] = NULL;
        return (0);
}
DEF_WEAK(putenv);

/*
 * setenv --
 *      Set the value of the environmental variable "name" to be
 *      "value".  If rewrite is set, replace any current value.
 */
int
setenv(const char *name, const char *value, int rewrite)
{
        char *C, **P;
        const char *np;
        int l_value, offset = 0;

        if (!name || !*name) {
                errno = EINVAL;
                return (-1);
        }
        for (np = name; *np && *np != '='; ++np)
                ;
        if (*np) {
                errno = EINVAL;
                return (-1);                    /* has `=' in name */
        }

        l_value = strlen(value);
        if ((C = __findenv(name, (int)(np - name), &offset)) != NULL) {
                int tmpoff = offset + 1;
                if (!rewrite)
                        return (0);
#if 0 /* XXX - existing entry may not be writable */
                if (strlen(C) >= l_value) {     /* old larger; copy over */
                        while ((*C++ = *value++))
                                ;
                        return (0);
                }
#endif
                /* could be set multiple times */
                while (__findenv(name, (int)(np - name), &tmpoff)) {
                        for (P = &environ[tmpoff];; ++P)
                                if (!(*P = *(P + 1)))
                                        break;
                }
        } else {                                        /* create new slot */
                size_t cnt = 0;

                if (environ != NULL) {
                        for (P = environ; *P != NULL; P++)
                                ;
                        cnt = P - environ;
                }
                P = reallocarray(lastenv, cnt + 2, sizeof(char *));
                if (!P)
                        return (-1);
                if (lastenv != environ && environ != NULL)
                        memcpy(P, environ, cnt * sizeof(char *));
                lastenv = environ = P;
                offset = cnt;
                environ[cnt + 1] = NULL;
        }
        if (!(environ[offset] =                 /* name + `=' + value */
            malloc((int)(np - name) + l_value + 2)))
                return (-1);
        for (C = environ[offset]; (*C = *name++) && *C != '='; ++C)
                ;
        for (*C++ = '='; (*C++ = *value++); )
                ;
        return (0);
}
DEF_WEAK(setenv);

/*
 * unsetenv(name) --
 *      Delete environmental variable "name".
 */
int
unsetenv(const char *name)
{
        char **P;
        const char *np;
        int offset = 0;

        if (!name || !*name) {
                errno = EINVAL;
                return (-1);
        }
        for (np = name; *np && *np != '='; ++np)
                ;
        if (*np) {
                errno = EINVAL;
                return (-1);                    /* has `=' in name */
        }

        /* could be set multiple times */
        while (__findenv(name, (int)(np - name), &offset)) {
                for (P = &environ[offset];; ++P)
                        if (!(*P = *(P + 1)))
                                break;
        }
        return (0);
}
DEF_WEAK(unsetenv);