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* Copyright (c) 1987 Regents of the University of California.
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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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* 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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. 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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* 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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#if defined(LIBC_SCCS) && !defined(lint)
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/*static char *sccsid = "from: @(#)setenv.c 5.6 (Berkeley) 6/4/91";*/
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static char *rcsid = "$Id: setenv.c,v 1.5 1996/09/04 22:10:42 sjg Exp $";
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#endif /* LIBC_SCCS and not lint */
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* Returns pointer to value associated with name, if any, else NULL.
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* Sets offset to be the offset of the name/value combination in the
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* environmental array, for use by setenv(3) and unsetenv(3).
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* Explicitly removes '=' in argument name.
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* This routine *should* be a static; don't use it.
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__findenv(name, offset)
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extern char **environ;
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register char **P, *C;
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for (C = name, len = 0; *C && *C != '='; ++C, ++len);
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for (P = environ; *P; ++P)
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if (!strncmp(*P, name, len))
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if (*(C = *P + len) == '=') {
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*offset = P - environ;
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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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setenv(name, value, rewrite)
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register const char *name;
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register const char *value;
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extern char **environ;
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static int alloced; /* if allocated space before */
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if (*value == '=') /* no `=' in 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 (strlen(C) >= l_value) { /* old larger; copy over */
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while (*C++ = *value++);
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} else { /* create new slot */
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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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else { /* get new space */
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alloced = 1; /* copy old entries into it */
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P = (char **)malloc((size_t)(sizeof(char *) *
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bcopy(environ, P, cnt * sizeof(char *));
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environ[cnt + 1] = NULL;
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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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for (C = environ[offset]; (*C = *name++) && *C != '='; ++C)
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for (*C++ = '='; *C++ = *value++; )
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* Delete environmental variable "name".
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extern char **environ;
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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)))
added
removed
setenv.c
