TRAMP: error in tramp-handle-file-exists-p

[Chris Moore]

I was just using TRAMP to access a remote machine.  Something went
wrong with the network connection, and things started locking up.
Eventually, I saw this error:

Debugger entered--Lisp error: (wrong-type-argument stringp nil)
  format(nil "/home/dooglus/public_html/gaim/")
  tramp-handle-file-exists-p("/scp:lukhas:/home/dooglus/public_html/gaim/")
  apply(tramp-handle-file-exists-p
  "/scp:lukhas:/home/dooglus/public_html/gaim/")
  tramp-sh-file-name-handler(file-exists-p
  "/scp:lukhas:/home/dooglus/public_html/gaim/")
  apply(tramp-sh-file-name-handler file-exists-p
  "/scp:lukhas:/home/dooglus/public_html/gaim/")
  tramp-file-name-handler(file-exists-p
  "/scp:lukhas:/home/dooglus/public_html/gaim/")
  file-exists-p("/scp:lukhas:/home/dooglus/public_html/gaim/")
  tramp-handle-file-attributes("/scp:lukhas:/home/dooglus/public_html/gaim/")
  apply(tramp-handle-file-attributes
  "/scp:lukhas:/home/dooglus/public_html/gaim/")
  tramp-sh-file-name-handler(file-attributes
  "/scp:lukhas:/home/dooglus/public_html/gaim/")
  apply(tramp-sh-file-name-handler file-attributes
  "/scp:lukhas:/home/dooglus/public_html/gaim/")
  tramp-file-name-handler(file-attributes
  "/scp:lukhas:/home/dooglus/public_html/gaim/")
  file-attributes("/scp:lukhas:/home/dooglus/public_html/gaim/")
  dired-directory-changed-p("/scp:lukhas:/home/dooglus/public_html/gaim/")
  dired-internal-noselect("/scp:lukhas:/home/dooglus/public_html/gaim/"
  nil)
  dired-noselect("/scp:lukhas:/home/dooglus/public_html/gaim/" nil)
  dired-other-window("/scp:lukhas:/home/dooglus/public_html/gaim/"
  nil)
  call-interactively(dired-other-window)


tramp-handle-file-exists-p makes this call:

    (format
       (tramp-get-file-exists-command multi-method method user host)
              (tramp-shell-quote-argument localname))

It seems that tramp-get-file-exists-command is capable of returning
nil, which is passed as the first argument to format, which format
doesn't like.  We need to either check the return from
tramp-get-file-exists-command before passing it to format, or change
tramp-handle-file-exists-p to stop it returning nil in some cases.


In GNU Emacs 22.0.93.34 (i686-pc-linux-gnu, GTK+ Version 2.8.20)
 of 2007-02-09 on trpaslik
X server distributor `The X.Org Foundation', version 11.0.70101000
configured using `configure  '--with-gtk' '--prefix' '/usr/local'
 '--with-xpm' '--with-jpeg' '--with-png' '--with-gif''