Re: so-called pipe files (sh-np-*) do not get deleted when processes close.

[Michael Felt]

On 11/03/2021 18:11, Chet Ramey wrote:
> On 3/11/21 11:28 AM, Michael Felt wrote:
> > Hi,
> >
> > Issue: AdoptOpenJDK build process makes bash calls in a particular 
> > way. An abbreviated (shorter pathnames) example is:
> >
> > ```
> > bash-5.0$ /usr/bin/printf "Building targets 'product-images 
> > legacy-jre-image test-image' in configuration 
> > 'aix-ppc64-normal-server-release'\n" > >(/usr/bin/tee -a 
> > /home/aixtools/build.log) 2> >(/usr/bin/tee -a 
> > /home/aixtools/build.log >&2)
> > Building targets 'product-images legacy-jre-image test-image' in 
> > configuration 'aix-ppc64-normal-server-release'
>
> I believe this is fixed in bash-5.1.
>
>
> > I added some debug statements to try and catch what is not happening. 
> > It seems that the fifo_list[i].proc value is never being set to 
> > (pid_t)-1 so any call to `unlink_fifo()` or `unlink_fifo_list()` does 
> > not unlink the special file created.
>
> Probably because the process substitution does not exit before the 
> shell does.
I spent several days debugging - and, basically, they never get cleared 
because the fifo_struct never gets the (pid_t) -1 value assigned.

Although the `reap` function does get called - there is never anything 
to do.

The routine that does assign the (pid_t) -1 value is `wait`*something - 
and this is only called via an interrupt (aka signal) - as far as I 
could see.


in the end I came up with a very simple - basically historical solution 
- for working with tempoary files that do not need to survive the 
process - unlink() the file immediately after open()>

As I need to document for AdoptOpenJDK I created a mirror of savannah 
(git) and created a PR: https://github.com/aixtools/bash/pull/2

I expect much more testing is warrented - as to potential side-effects 
with the fifo struct (that is no longer accurate as the file may (read 
should) already be unlinked.

Hope this helps,

Michael

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