[HEADSUP] Disallowing read() of a directory fd

[Poul-Henning Kamp]

--------
In message <CACNAnaFszg+QWPRS0kghsnQMxXc+5niPTTNiUPSmK60YyBGCzA at mail.gmail.com>

>This is a heads up, given that I'm completely flipping our historical
>behavior- I intend to commit this review in a couple days' time
>without substantial objection: https://reviews.freebsd.org/D24596

When we did UFS2, I tried to persuade Kirk and Robert that since
directories had the 'x' bit set anyway, they start with a magic
sequence of:

    0x23 0x21 0x2f 0x62 0x69 0x6e 0x2f 0x6c 0x73 0x20 0x2d 0x6c 0x0a 

As you can probably guess, they nixed my idea, and now you're making
it impossible for ever :-(

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.