source: asp3_tinet_ecnl_rx/trunk/musl-1.1.18/src/env/unsetenv.c@ 337

#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include "libc.h"

char *__strchrnul(const char *, int);

#ifndef __c2__
static void dummy(char *old, char *new) {}
weak_alias(dummy, __env_rm_add);
#else
extern void __env_rm_add(char *old, char *new);
#endif

int unsetenv(const char *name)
{
        size_t l = __strchrnul(name, '=') - name;
        if (!l || name[l]) {
                errno = EINVAL;
                return -1;
        }
        if (__environ) {
                char **e = __environ, **eo = e;
                for (; *e; e++)
                        if (!strncmp(name, *e, l) && l[*e] == '=')
                                __env_rm_add(*e, 0);
                        else if (eo != e)
                                *eo++ = *e;
                        else
                                eo++;
                if (eo != e) *eo = 0;
        }
        return 0;
}