minix/lib/libc/other/putenv.c

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/*
* (c) copyright 1989 by the Vrije Universiteit, Amsterdam, The Netherlands.
* See the copyright notice in the ACK home directory, in the file "Copyright".
*/
/* $Header$ */
#include <stdlib.h>
#include <string.h>
#define ENTRY_INC 10
#define rounded(x) (((x / ENTRY_INC) + 1) * ENTRY_INC)
extern _CONST char ***_penviron;
int
putenv(name)
char *name;
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{
register _CONST char **v = *_penviron;
register char *r;
static int size = 0;
/* When size != 0, it contains the number of entries in the
* table (including the final NULL pointer). This means that the
* last non-null entry is environ[size - 2].
*/
if (!name) return 0;
if (*_penviron == NULL) return 1;
if ((r = strchr(name, '='))) {
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register _CONST char *p, *q;
*r = '\0';
if (v != NULL) {
while ((p = *v) != NULL) {
q = name;
while (*q && (*q++ == *p++))
/* EMPTY */ ;
if (*q || (*p != '=')) {
v++;
} else {
/* The name was already in the
* environment.
*/
*r = '=';
*v = name;
return 0;
}
}
}
*r = '=';
v = *_penviron;
}
if (!size) {
register _CONST char **p;
register int i = 0;
if (v)
do {
i++;
} while (*v++);
if (!(v = malloc(rounded(i) * sizeof(char **))))
return 1;
size = i;
p = *_penviron;
*_penviron = v;
while ((*v++ = *p++)); /* copy the environment */
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v = *_penviron;
} else if (!(size % ENTRY_INC)) {
if (!(v = realloc(*_penviron, rounded(size) * sizeof(char **))))
return 1;
*_penviron = v;
}
v[size - 1] = name;
v[size] = NULL;
size++;
return 0;
}