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#include <stdlib.h>
#include <string.h>
#include <errno.h>
char *__strchrnul(const char *, int);
int __putenv(char *, size_t, char *);
void __env_rm_add(char *old, char *new)
{
static char **env_alloced;
static size_t env_alloced_n;
for (size_t i=0; i < env_alloced_n; i++)
if (env_alloced[i] == old) {
env_alloced[i] = new;
free(old);
return;
} else if (!env_alloced[i] && new) {
env_alloced[i] = new;
new = 0;
}
if (!new) return;
char **t = realloc(env_alloced, sizeof *t * (env_alloced_n+1));
if (!t) return;
(env_alloced = t)[env_alloced_n++] = new;
}
int setenv(const char *var, const char *value, int overwrite)
{
char *s;
size_t l1, l2;
if (!var || !(l1 = __strchrnul(var, '=') - var) || var[l1]) {
errno = EINVAL;
return -1;
}
if (!overwrite && getenv(var)) return 0;
l2 = strlen(value);
s = malloc(l1+l2+2);
if (!s) return -1;
memcpy(s, var, l1);
s[l1] = '=';
memcpy(s+l1+1, value, l2+1);
return __putenv(s, l1, s);
}
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