Just because it is documented as thread safe doesn't mean it actually is. They might have just not understood the problem (see e.g. the various indirect links to "please mandate a thread-local `getenv`").
`setenv` is a nasty beast, especially since the raw `environ` variable is also exposed (and is in fact the only way to enumerate the environment).
`setenv` is a nasty beast, especially since the raw `environ` variable is also exposed (and is in fact the only way to enumerate the environment).