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Date: Thu, 14 May 2020 16:53:16 -0700 (PDT)
From: Don Lewis <truckman@FreeBSD.org>
Subject: Re: [HEADSUP] Disallowing read() of a directory fd
To: Cy Schubert <Cy.Schubert@cschubert.com>
cc: Kyle Evans <kevans@freebsd.org>, 
 "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org>
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On 14 May, Cy Schubert wrote:
> In message <CACNAnaFszg+QWPRS0kghsnQMxXc+5niPTTNiUPSmK60YyBGCzA@mail.gmail.c
> om>
> , Kyle Evans writes:
>> Hi,
>>
>> 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
>>
>> With this, FreeBSD 13 will not allow read() of a directory fd, which
>> could have previously returned some data from the underlying
>> filesystem in no particular standardized format.
>>
>> This is a still-standards-compliant switch from one
>> implementation-defined behavior to another that's already been adopted
>> in various other popular kernels, to include OpenBSD, MacOS, and
>> Linux.
>>
>> Worth noting is that there's not really one largely-compelling reasons
>> to switch this after so many years (unless you find yourself that
>> irate when you accidentally `cat` a directory), but there are some
>> benefits which are briefly discussed in the commentary around the
>> review along with the history of the current behavior.
>>
>> This change also simplifies filesystem implementations to some extent.
> 
> OpenBSD has done this for a while and more importantly Linux.

Which causes annoying noise to stderr if you 'grep something *' if there
are directories in the working directory.