Date: Thu, 14 May 2020 22:30:30 +0200 From: Arne Steinkamm <freebsd-hackers@Steinkamm.COM> To: Alan Somers <asomers@freebsd.org> Cc: "Julian H. Stacey" <jhs@berklix.com>, Kyle Evans <kevans@freebsd.org>, "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org>, "freebsd-hackers@freebsd.org" <hackers@freebsd.org>, arne@steinkamm.com Subject: Re: [HEADSUP] Disallowing read() of a directory fd Message-ID: <20200514203030.GT82984@trajan.stk.cx> In-Reply-To: <CAOtMX2i2Z-KX=3rYR2nZ1g1Lb_tF==H3xPKcQMBxJs1Kqr-meQ@mail.gmail.com> References: <CACNAnaFszg%2BQWPRS0kghsnQMxXc%2B5niPTTNiUPSmK60YyBGCzA@mail.gmail.com> <202005142017.04EKH0aA093503@fire.js.berklix.net> <CAOtMX2i2Z-KX=3rYR2nZ1g1Lb_tF==H3xPKcQMBxJs1Kqr-meQ@mail.gmail.com>
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On Thu, May 14, 2020 at 02:20:45PM -0600, Alan Somers wrote: > On Thu, May 14, 2020 at 2:17 PM Julian H. Stacey <jhs@berklix.com> wrote: > > > Kyle Evans wrote: > > > 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. > > > > > > Thanks, > > > > > > Kyle Evans > > > > There is ZERO need for a spurious change at 2 days notice after 42+ years ! > > > > "cat ." as been supported since Unix V6 1978 or earlier, > > no problem, even occasionaly useful. > > > > Really? When is that occasionally useful? I've never seen anything useful > come out of reading a directory. It's all about files in Unix... This is true since 1972. And files can be read! How many (bad programmed) shell scripts will break when directory files can't be read anymore? I have no idea. But I know for sure that there is no need to make this change. Not 1976, not 2020 nor in the future. .//. Arne -- Arne Steinkamm | Home: Mail: arne<at>steinkamm<dot>com
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