Fermeture des file descriptors standard et conformance à POSIX

[dariuskramer]

Les tests qui vérifie la fermeture d'un fd standard avec l'opérateur &-, par exemple 21sh > redirections > inputs > 001-close-stdin, sont marqués comme échoué si le fd est remappé sur /dev/null.

Hors la Rationale, et par extension POSIX, ne recommande pas ce comportement.
Cf http://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xcu_chap02.html, section C.2.7 Redirection:

Applications should not use the [n]<&- or [n]>&- operators to execute a utility or application with file descriptor 0 not open for reading or with file descriptor 1 or 2 not open for writing, as this might cause the executed program (or shell built-in) to misbehave. In order not to pass on these file descriptors to an executed utility or application, applications should not just close them but should reopen them on, for example, /dev/null. Some implementations may reopen them automatically, but applications should not rely on this being done.

Un possible fix serait que si le premier call à read retourne 0, alors on suppose que le fd est mappé sur /dev/null.