1#include <stdlib.h>
 2#include <string.h>
 3#include <unistd.h>
 4
 5static void dummy(char *old, char *new) {}
 6weak_alias(dummy, __env_rm_add);
 7
 8int __putenv(char *s, size_t l, char *r)
 9{
10	size_t i=0;
11	if (__environ) {
12		for (char **e = __environ; *e; e++, i++)
13			if (!strncmp(s, *e, l+1)) {
14				char *tmp = *e;
15				*e = s;
16				__env_rm_add(tmp, r);
17				return 0;
18			}
19	}
20	static char **oldenv;
21	char **newenv;
22	if (__environ == oldenv) {
23		newenv = realloc(oldenv, sizeof *newenv * (i+2));
24		if (!newenv) goto oom;
25	} else {
26		newenv = malloc(sizeof *newenv * (i+2));
27		if (!newenv) goto oom;
28		if (i) memcpy(newenv, __environ, sizeof *newenv * i);
29		free(oldenv);
30	}
31	newenv[i] = s;
32	newenv[i+1] = 0;
33	__environ = oldenv = newenv;
34	if (r) __env_rm_add(0, r);
35	return 0;
36oom:
37	free(r);
38	return -1;
39}
40
41int putenv(char *s)
42{
43	size_t l = __strchrnul(s, '=') - s;
44	if (!l || !s[l]) return unsetenv(s);
45	return __putenv(s, l, 0);
46}