GNU bug report logs - #13013
24.3.50; Windows XP bug? get-file-buffer, file-name-as-directory

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Jambunathan K <kjambunathan <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Cc: Ista Zahn <istazahn <at> gmail.com>
Subject: 24.3.50; Windows XP bug? get-file-buffer, file-name-as-directory
Date: Tue, 27 Nov 2012 22:54:57 +0530

This report is a digest of following thread:
    http://www.mail-archive.com/emacs-orgmode <at> gnu.org/msg62455.html.

The problem is because of Emacs mangling file paths like this on Windows
XP.

    "c:/DOCUME~1/IZAHN/LOCALS~1/Temp/odt-8052VuJ/"
    "c:/Documents and Settings/IZAHN/Local Settings/Temp/odt-8052VuJ/content.xml"

The problem is better explained with ielm session below. 


Create a ielm buffer with 
    M-x ielm RET

and type out the following 4 lisp forms ONE-by-ONE.

    (setq org-e-odt-zip-dir (file-name-as-directory (make-temp-file "odt-" t)))

    (with-current-buffer (find-file-noselect (concat org-e-odt-zip-dir "content.xml") t) (buffer-file-name))

    (with-current-buffer (get-file-buffer (concat org-e-odt-zip-dir "content.xml")) (save-buffer 0))

    (get-file-buffer (concat org-e-odt-zip-dir "content.xml"))

Here is what Ista reports:

    *** Welcome to IELM ***  Type (describe-mode) for help.
    ELISP> (setq org-e-odt-zip-dir (file-name-as-directory (make-temp-file
    "odt-" t)))
    "c:/DOCUME~1/IZAHN/LOCALS~1/Temp/odt-8052VuJ/"
    ELISP> (with-current-buffer (find-file-noselect (concat
    org-e-odt-zip-dir "content.xml") t) (buffer-file-name))
    "c:/Documents and Settings/IZAHN/Local Settings/Temp/odt-8052VuJ/content.xml"
    ELISP> (with-current-buffer (get-file-buffer (concat org-e-odt-zip-dir
    "content.xml")) (save-buffer 0))
    *** Eval error ***  Wrong type argument: stringp, nil
    ELISP> (get-file-buffer (concat org-e-odt-zip-dir "content.xml"))
    nil
    ELISP>

I am surprised that `get-file-buffer' is returning nil.  Why is there a
mismatch between file names as reported by `file-name-as-directory' and
`buffer-file-name'.


The problem is seen with Ista's machine (CCed here) with the following
setup.
    ,----
    | GNU Emacs 24.2.1 (i386-mingw-nt5.1.2600) of 2012-08-28 on MARVIN
    | 
    | I have cygwin installed, but emacs is the windows version from
    | http://ftp.gnu.org/gnu/emacs/windows/
    | 
    | The OS is Windows XP professional with service pack 3.
    `----

Apparently the problem is not seen with either here or 
    ,----
    | Windows 7
    | GNU Emacs 24.2.1 (i386-mingw-nt6.1.7601) of 2012-08-29 on MARVIN
    `----

here 
    ,----
    | GNU Emacs 24.2.1 (i386-mingw-nt6.1.7601) of 2012-08-29 on MARVIN
    | Windows 7
    `----

Message #8 received at 13013 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Jambunathan K <kjambunathan <at> gmail.com>
Cc: istazahn <at> gmail.com, 13013 <at> debbugs.gnu.org
Subject: Re: bug#13013: 24.3.50;
	Windows XP bug? get-file-buffer, file-name-as-directory
Date: Tue, 27 Nov 2012 20:01:19 +0200

> From: Jambunathan K <kjambunathan <at> gmail.com>
> Date: Tue, 27 Nov 2012 22:54:57 +0530
> Cc: Ista Zahn <istazahn <at> gmail.com>
> 
> 
> This report is a digest of following thread:
>     http://www.mail-archive.com/emacs-orgmode <at> gnu.org/msg62455.html.

I will read it soon, for now replying only based on what you posted.

> The problem is because of Emacs mangling file paths like this on Windows
> XP.
> 
>     "c:/DOCUME~1/IZAHN/LOCALS~1/Temp/odt-8052VuJ/"
>     "c:/Documents and Settings/IZAHN/Local Settings/Temp/odt-8052VuJ/content.xml"

Emacs doesn't mangle file names.  Emacs uses the value of TEMP
environment variable, which Windows sets to a 8+3 alias of the long
name (evidently trying to avoid bugs in programs that don't handle
whitespace in file names).  Emacs then converts the 8+3 alias to the
full long name when it stores the file name in the buffer object of
the buffer that visits the file.

> Create a ielm buffer with 
>     M-x ielm RET
> 
> and type out the following 4 lisp forms ONE-by-ONE.
> 
>     (setq org-e-odt-zip-dir (file-name-as-directory (make-temp-file "odt-" t)))
> 
>     (with-current-buffer (find-file-noselect (concat org-e-odt-zip-dir "content.xml") t) (buffer-file-name))
> 
>     (with-current-buffer (get-file-buffer (concat org-e-odt-zip-dir "content.xml")) (save-buffer 0))
> 
>     (get-file-buffer (concat org-e-odt-zip-dir "content.xml"))

The solution is to call file-truename on

  (concat org-e-odt-zip-dir "content.xml")

Think of the 8+3 name as a symlink to the long file name.

> I am surprised that `get-file-buffer' is returning nil.

It returns nil because it compares file names with string-equal.

> Why is there a mismatch between file names as reported by
> `file-name-as-directory' and `buffer-file-name'.

See above.  Won't the same happen with symlinks?

Message #11 received at 13013 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 13013 <at> debbugs.gnu.org, Jambunathan K <kjambunathan <at> gmail.com>,
	istazahn <at> gmail.com
Subject: Re: bug#13013: 24.3.50;
	Windows XP bug? get-file-buffer, file-name-as-directory
Date: Tue, 27 Nov 2012 13:38:13 -0500

>> I am surprised that `get-file-buffer' is returning nil.
> It returns nil because it compares file names with string-equal.

I think this brings us back to a recent suggestion to get rid of
get-file-buffer and redefine it as an alias of find-buffer-visiting
(which should work fine in this case).


        Stefan

Message #14 received at 13013 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: kjambunathan <at> gmail.com, istazahn <at> gmail.com
Cc: 13013 <at> debbugs.gnu.org
Subject: Re: bug#13013: 24.3.50;
	Windows XP bug? get-file-buffer, file-name-as-directory
Date: Tue, 27 Nov 2012 20:59:33 +0200

> Date: Tue, 27 Nov 2012 20:01:19 +0200
> From: Eli Zaretskii <eliz <at> gnu.org>
> Cc: istazahn <at> gmail.com, 13013 <at> debbugs.gnu.org
> 
> > From: Jambunathan K <kjambunathan <at> gmail.com>
> > Date: Tue, 27 Nov 2012 22:54:57 +0530
> > Cc: Ista Zahn <istazahn <at> gmail.com>
> > 
> > 
> > This report is a digest of following thread:
> >     http://www.mail-archive.com/emacs-orgmode <at> gnu.org/msg62455.html.
> 
> I will read it soon, for now replying only based on what you posted.

Read it, but didn't learn anything useful.

> The problem is seen with Ista's machine (CCed here) with the following
> setup.
>     ,----
>     | GNU Emacs 24.2.1 (i386-mingw-nt5.1.2600) of 2012-08-28 on MARVIN
>     | 
>     | I have cygwin installed, but emacs is the windows version from
>     | http://ftp.gnu.org/gnu/emacs/windows/
>     | 
>     | The OS is Windows XP professional with service pack 3.
>     `----
> 
> Apparently the problem is not seen with either here or 
>     ,----
>     | Windows 7
>     | GNU Emacs 24.2.1 (i386-mingw-nt6.1.7601) of 2012-08-29 on MARVIN
>     `----
> 
> here 
>     ,----
>     | GNU Emacs 24.2.1 (i386-mingw-nt6.1.7601) of 2012-08-29 on MARVIN
>     | Windows 7
>     `----

Because Windows 7 doesn't put a 8+3 alias into TEMP, but instead uses
the full long file name.  Probably because XP still supports DOS
programs (via NTVDM), while Windows 7 tossed that support.

IOW, it works on Windows 7 "by sheer luck".

Message #17 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Achim Gratz <Stromeko <at> nexgo.de>
To: bug-gnu-emacs <at> gnu.org
Subject: Re: bug#13013: 24.3.50;
	Windows XP bug? get-file-buffer, file-name-as-directory
Date: Tue, 27 Nov 2012 20:23:08 +0100

Eli Zaretskii writes:
> Because Windows 7 doesn't put a 8+3 alias into TEMP, but instead uses
> the full long file name.  Probably because XP still supports DOS
> programs (via NTVDM), while Windows 7 tossed that support.

Win7 may not support DOS programs, but it still supports 8+3 filenames,
this is one of the easier ways to escape quoting hell on that platform.


Regards,
Achim.
-- 
+<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+

SD adaptation for Waldorf rackAttack V1.04R1:
http://Synth.Stromeko.net/Downloads.html#WaldorfSDada

Message #20 received at 13013 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Achim Gratz <Stromeko <at> nexgo.de>
Cc: 13013 <at> debbugs.gnu.org
Subject: Re: bug#13013: 24.3.50;
	Windows XP bug? get-file-buffer, file-name-as-directory
Date: Tue, 27 Nov 2012 21:52:47 +0200

> From: Achim Gratz <Stromeko <at> nexgo.de>
> Date: Tue, 27 Nov 2012 20:23:08 +0100
> 
> Eli Zaretskii writes:
> > Because Windows 7 doesn't put a 8+3 alias into TEMP, but instead uses
> > the full long file name.  Probably because XP still supports DOS
> > programs (via NTVDM), while Windows 7 tossed that support.
> 
> Win7 may not support DOS programs, but it still supports 8+3 filenames,

Of course it does.  I never said it didn't.  I attempted to explain
why XP sets TEMP to something like C:\DOCUME~1\USERNAME\LOCALS~1\Temp,
whereas Windows 7 sets it to C:\Users\USERNAME\APPDATA\Local\Temp.

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