common/bsd/setenv.c

#if defined(LIBC_SCCS) && !defined(lint)
static const char sccsid[] = "@(#)setenv.c  8.1 (Berkeley) 6/4/93";
static const char rcsid[] = "$Id: setenv.c,v 1.2 2005/04/27 04:56:11 sra Exp $";
#endif /* LIBC_SCCS and not lint */

/*
 * 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.
 */

#include "port_before.h"

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

#include "port_after.h"

#if !defined(NEED_SETENV)
int __bindcompat_setenv;
#else

extern char **environ;

static char *findenv(const char *name, int *offset);

/*%
 * setenv --
 *  Set the value of the environmental variable "name" to be
 *  "value".  If rewrite is set, replace any current value.
 */
setenv(const char *name, const char *value, int rewrite) {
    extern char **environ;
    static int alloced;         /*%< if allocated space before */
    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 */
        int cnt;
        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 = 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);
    for (c = environ[offset]; (*c = *name++) && *c != '='; ++c);
    for (*c++ = '='; *c++ = *value++;);
    return (0);
}

/*%
 * unsetenv(name) --
 *  Delete environmental variable "name".
 */
void
unsetenv(const char *name) {
    char **p;
    int offset;

    while (findenv(name, &offset))  /*%< if set multiple times */
        for (p = &environ[offset];; ++p)
            if (!(*p = *(p + 1)))
                break;
}

/*%
 * 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.
 */
static char *
findenv(const char *name, int *offset) {
    const char *np;
    char **p, *c;
    int len;

    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

/*! \file */