Subject: Re: bug#1741: 23.0.60; vc fail to register file while logged as /su:: with tramp

From: [email-masked]
Date: Wed, 08 Apr 2009 13:23:48 +0200

Hi Dan!
Thank you to have a look at this bug.
It's a long time, i didn't remember i sent this bug.
The bug is still here.(23.0.92)

Dan Nicolaescu <[email-masked]> writes:

> Thierry Volpiatto <[email-masked]> writes:
>
>   > Please write in English if possible, because the Emacs maintainers
>   > usually do not have translators to read other languages for them.
>   > 
>   > Your bug report will be posted to the [email-masked] mailing list.
>   > 
>   > Please describe exactly what actions triggered the bug
>   > and the precise symptoms of the bug:
>   > 
>   > Hi, 
>   > i can't register a file with vc/rcs when i am logged as root throught
>   > tramp.
>   > 1) C-x v i
>   > 2) Create RCS dir (y/n) ==> The dir is created.
>   > 3) But now ==> _Here the debug output_:
>   > 
>   > ,----
>   > | Debugger entered--Lisp error: (wrong-type-argument stringp nil)
>   > |   file-exists-p(nil)
>   > |   vc-insert-file(nil "^[0-9]")
>   > |   vc-rcs-fetch-master-state("/su:[email-masked]:/usr/local/bin/editeur.sh")
>   > |   vc-rcs-working-revision("/su:[email-masked]:/usr/local/bin/editeur.sh")
>   > |   apply(vc-rcs-working-revision "/su:[email-masked]:/usr/local/bin/editeur.sh")
>   > |   vc-call-backend(RCS working-revision "/su:[email-masked]:/usr/local/bin/editeur.sh")
>   > |   vc-working-revision("/su:[email-masked]:/usr/local/bin/editeur.sh")
>   > |   vc-default-mode-line-string(RCS "/su:[email-masked]:/usr/local/bin/editeur.sh")
>   > |   apply(vc-default-mode-line-string RCS "/su:[email-masked]:/usr/local/bin/editeur.sh")
>   > |   vc-call-backend(RCS mode-line-string "/su:[email-masked]:/usr/local/bin/editeur.sh")
>   > |   vc-mode-line("/su:[email-masked]:/usr/local/bin/editeur.sh")
>   > |   run-hook-with-args(vc-mode-line "/su:[email-masked]:/usr/local/bin/editeur.sh")
>   > |   vc-resynch-window("/su:[email-masked]:/usr/local/bin/editeur.sh" t t)
>   > |   vc-resynch-buffer("/su:[email-masked]:/usr/local/bin/editeur.sh" t t)
>   > | 
>   > | [...]
>   > | 
>   > | [G70600 G70601 rev comment file --cl-dolist-temp-- 
>   > | message "Registering %s... " mapc vc-file-clearprops vc-call-backend
>   > |   register nil vc-file-setprop 
>   > | vc-backend "Registering %s... done"] 6] (quote --files--) (quote --backend--) --cl-rest--)))
>   > |   vc-register(nil)
>   > |   call-interactively(vc-register nil nil)
>   > `----
>   > 
>   > _And if i want to delete RCS directory from dired_:
>   > 
>   > ,----
>   > | (file-error Couldn't delete /su:[email-masked]:/usr/local/bin/RCS)
>   > `----
>   > 
>   > However if i open an emacs  root session i can register my file as
>   > normal.
>
> What happens is that vc-check-master-templates gets called with
> "/su:[email-masked]:/usr/local/bin/editeur.sh", and it calls 
> (file-exists-p "/su:[email-masked]:/usr/local/bin/editeur.sh")
> which returns nil.
No, `file-exists-p' recognize tramp file name and return t.

(file-exists-p "/su:[email-masked]:/usr/local/bin/editeur.sh")
==>t

The problem is, i think, vc call `file-exists-p' with (vc-name fname) as
argument instead of "file_name":

,----[ With a tramp filename return error ]
| (file-exists-p (vc-name "/su:[email-masked]:/usr/local/bin/editeur.sh"))
| ==>
| Debugger entered--Lisp error: (wrong-type-argument stringp nil)
|   file-exists-p(nil)
|   eval((file-exists-p (vc-name "/su:[email-masked]:/usr/local/bin/editeur.sh")))
|   eval-expression((file-exists-p (vc-name "/su:[email-masked]:/usr/local/bin/editeur.sh")) nil)
|   call-interactively(eval-expression nil nil)
`----

,----[ With a regular filename return t ]
| (file-exists-p (vc-name "~/bin/call-gnus.sh"))
| ==>t
`----

So it seem the problem come from vc that try to set properties on
filename with `vc-name' and fail on tramp filename.
(`vc-name' call `vc-file-getprop')

Thought i didn't look at the code carefully, so i am may be wrong.

> There's a few other `file-exists-p' calls in vc*.el, so it's likely that
> other things can go wrong if this one instance is somehow fixed.
>
> If someone familiar with what tramp needs wants to get this to work,
> about all vc calls need to be tested to make sure they don't do
> something that tramp can't do.
>

-- 
A + Thierry Volpiatto
Location: Saint-Cyr-Sur-Mer - France