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

[Michael Felt]

OK - this process on github has not gone exactly as I intended - merged 
with master - while I wanted to update, ie., merge with branch 5.0.18. 
So, the link may not be accurate.

The change is simple:

diff --git a/subst.c b/subst.c
index 843c9d39..3792e45c 100644
--- a/subst.c
+++ b/subst.c
@@ -5926,6 +5926,8 @@ process_substitute (string, open_for_read_in_child)
 #if !defined (HAVE_DEV_FD)
   /* Open the named pipe in the child. */
   fd = open (pathname, open_for_read_in_child ? O_RDONLY : O_WRONLY);
+  /* now that the file is open (or not) * unlink it to keep garbage down */
+  unlink(pathname);
   if (fd < 0)
     {
       /* Two separate strings for ease of translation. */


On 17/03/2021 16:17, Michael Felt wrote:
> 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

OpenPGP_0x722BFDB61F396FC2.asc
Description: OpenPGP public key

OpenPGP_signature
Description: OpenPGP digital signature