bash usage of fdescfs [was: Re: amd64/188699: Dev tree]

[Konstantin Belousov]

On Mon, Apr 21, 2014 at 11:52:59PM +0200, Emanuel Haupt wrote:
> On 21/04/14 21:51, Konstantin Belousov wrote:
> > On Mon, Apr 21, 2014 at 02:31:12PM -0400, John Baldwin wrote:
> >> On Thursday, April 17, 2014 2:50:01 pm Konstantin Belousov wrote:
> >>> The following reply was made to PR amd64/188699; it has been noted by GNATS.
> >>>
> >>> From: Konstantin Belousov <kostikbel at gmail.com>
> >>> To: John Allman <freebsd at hugme.org>
> >>> Cc: freebsd-gnats-submit at FreeBSD.org
> >>> Subject: Re: amd64/188699: Dev tree
> >>> Date: Thu, 17 Apr 2014 21:44:52 +0300
> >>>
> >>>   On Wed, Apr 16, 2014 at 05:32:45PM +0000, John Allman wrote:
> >>>   > This is how to reproduce it:
> >>>   >
> >>>   > Fresh install of 10 on AMD 64
> >>>   > install bash `pkg install bash`
> >>>   > Switch to bash `bash`
> >>>   > push a here document into a loop: `while true ; do echo; done< <(echo "123")`
> >>>   > receive an error: "-su: /dev/fd/62: No such file or directory"
> >>>   >
> >>>   > I'm sorry I haven't been able to research this any further. I found how while working on some important matters. As I mentioned the above works fine in all
> >> previous versions of FreeBSD up until 10.
> >>>   > >How-To-Repeat:
> >>>   > Fresh install
> >>>   > pkg install bash
> >>>   > bash
> >>>   > while true; do echo foo done< <(echo "123")
> >>>   >
> >>>   > -su: /dev/fd/62: No such file or directory
> >>>
> >>>   So do you have fdescfs mounted on /dev/fd on the machine where the
> >>>   test fails ?  It works for me on head, and if unmounted, I get the
> >>>   same failure message as yours.  I very much doubt that it has anything
> >>>   to do with a system version.
> >>
> >> Question I have is why is bash deciding to use /dev/fd/<n> and require
> >> fdescfs?  On older releases bash uses named pipes for this instead.
> >
> > The aclocal.m4 contains the test which verifies the presence and usability
> > of /dev/fd/n for n>=3 on the _build_ host.  The result of the test
> > is used on the installation host afterward.
> >
> > Such kinds of bugs are endemic in our ports, but apparently upstreams
> > are guilty too.
> 
> Is there anything I can do to patch the bash port? I am more than happy 
> to implement a fix and contact upstream about the problem.

Ideally, upstream should test the presence of fdescfs mount at runtime,
instead of the compile time.  They already have unused have_devfd
variable.

The port could add the pkg installation message which would mention
the need of the mount, like it is done by openjdk ports currently.
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