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scoutos / prex-0.9.0 / usr / lib / libc / stdlib / setenv.c @ 03e9c04a

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/*
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 * Copyright (c) 1987, 1993
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 *        The Regents of the University of California.  All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 * 3. Neither the name of the University nor the names of its contributors
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 *    may be used to endorse or promote products derived from this software
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 *    without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 */
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#include <stddef.h>
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#include <stdlib.h>
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#include <string.h>
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extern char **environ;
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char *__findenv(const char *, int *);
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/*
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 * setenv --
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 *        Set the value of the environmental variable "name" to be
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 *        "value".  If rewrite is set, replace any current value.
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 */
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int
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setenv(name, value, rewrite)
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        const char *name;
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        const char *value;
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        int rewrite;
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{
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        static int alloced;                        /* if allocated space before */
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        char *c;
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        int l_value, offset;
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        if (*value == '=')                        /* no `=' in value */
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                ++value;
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        l_value = strlen(value);
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        if ((c = __findenv(name, &offset))) {        /* find if already exists */
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                if (!rewrite)
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                        return (0);
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                if ((int)strlen(c) >= l_value) {        /* old larger; copy over */
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                        while ( (*c++ = *value++) );
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                        return (0);
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                }
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        } else {                                        /* create new slot */
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                int cnt;
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                char **p;
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                for (p = environ, cnt = 0; *p; ++p, ++cnt);
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                if (alloced) {                        /* just increase size */
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                        environ = (char **)realloc((char *)environ,
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                            (size_t)(sizeof(char *) * (cnt + 2)));
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                        if (!environ)
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                                return (-1);
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                }
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                else {                                /* get new space */
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                        alloced = 1;                /* copy old entries into it */
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                        p = malloc((size_t)(sizeof(char *) * (cnt + 2)));
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                        if (!p)
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                                return (-1);
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                        bcopy(environ, p, cnt * sizeof(char *));
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                        environ = p;
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                }
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                environ[cnt + 1] = NULL;
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                offset = cnt;
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        }
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        for (c = (char *)name; *c && *c != '='; ++c);        /* no `=' in name */
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        if (!(environ[offset] =                        /* name + `=' + value */
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            malloc((size_t)((int)(c - name) + l_value + 2))))
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                return (-1);
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        for (c = environ[offset]; (*c = *name++) && *c != '='; ++c);
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        for (*c++ = '='; (*c++ = *value++) != 0;);
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        return (0);
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}
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/*
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 * unsetenv(name) --
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 *        Delete environmental variable "name".
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 */
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void
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unsetenv(name)
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        const char *name;
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{
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        char **p;
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        int offset;
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        while (__findenv(name, &offset))        /* if set multiple times */
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                for (p = &environ[offset];; ++p)
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                        if (!(*p = *(p + 1)))
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                                break;
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}