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

char *__strchrnul(const char *, int);
int __unsetenv(const char *, size_t, char **);

static void dummy(char *p, char *r) {}
weak_alias(dummy, __env_change);

int __putenv(char *s, size_t l, char *r)
{
	size_t i=0;
	if (__environ)
		for (; __environ[i]; i++)
			if (!strncmp(__environ[i], s, l+1)) {
				char *tmp = __environ[i];
				__environ[i] = s;
				__env_change(tmp, r);
				return __unsetenv(s, l, __environ+i+1);
			}
	static char **oldenv;
	char **newenv;
	if (__environ == oldenv) {
		newenv = realloc(oldenv, sizeof *newenv * (i+2));
		if (!newenv) goto oom;
	} else {
		newenv = malloc(sizeof *newenv * (i+2));
		if (!newenv) goto oom;
		if (i) memcpy(newenv, __environ, sizeof *newenv * i);
		free(oldenv);
	}
	newenv[i] = s;
	newenv[i+1] = 0;
	__environ = oldenv = newenv;
	if (r) __env_change(0, r);
	return 0;
oom:
	free(r);
	return -1;
}

int putenv(char *s)
{
	size_t l = __strchrnul(s, '=') - s;
	if (!l || !s[l]) return unsetenv(s);
	return __putenv(s, l, 0);
}