21.3 peculiar error: directory-files fails on SAMBA 3.0.10 mounts

[Jari Aalto]

This is a peculiar error, which I have come accross several times, but
which is hard to demonstrate, because it appears randomly. In any
case, I'm reporting it so that perhaps inspecting the file reading
code in C level could reveal something.

There seems to be some reading problem with `directory-files' which is
sometimes unable to read local user's smbmount(1) directrories.

Test system:

  Debian/unstable
     
  ii  samba          3.0.10-1       a LanManager-like file and printer server fo
  ii  samba-common   3.0.10-1       Samba common files used by both the server a

Mounted as local user with smbmount(1). Target system is Windows 2000 sp4.
Output from mount(1):

  //w2kpicasso/jaalto on /home/jaalto/var/mount/jaalto type smbfs (rw)
        
Normal listing calls succeed at OS level:

  $ ls  /home/jaalto/var/mount/jaalto   OK

Normal dired calls succeed in Emacs too. I assume that's because
external ls(1) call is used:

  C-x d /home/jaalto/var/mount/jaalto

But lisp level call doesn't

  (directory-files "/home/jaalto/var/mount/jaalto")
  -> returns nil or sometimes message "interrupted system call" is
  flashed during tests.

  debug-on-error was t and debug-ignored-error nil during tests.

How the situation could possibly be triggered:

  1. Keep emacs running
  2. smbmount, smbumount file system several times
  3. try directory-files

The situation is corrected by shutting down emacs and starting it again, 
but the underlying problem is there waiting to appear again.

Jari