file-attributes returns negative integer for inode value

file-attributes returns negative integer for inode value

[Drew Adams]

emacs -Q
 
No reliable recipe to reproduce, but for me, some directories give a
negative inode number for file-attributes. For example:
 
M-x (file-attributes "c:/drews-lisp-20/Screenshots") gives:
 
(t 1 5 5 (18378 24192) (18123 40338) (18123 40337) 0
 "drwxrwxrwx" nil -3082 240391127)
 
The inode value here is -3082. The Elisp manual, however says that if
the integer is too large, then a cons is used for the inode value. Is
this a Windows-specific problem, perhaps?
 
Also, there is a typo in the doc string for `file-attributes':
 
  ...
  If inode number is larger than the Emacs integer,
  this is a cons cell containing two integers: first the high part,
  then the low 16 bits.
 
"the Emacs integer" should presumably be "the largest Emacs integer".
 

In GNU Emacs 22.1.90.1 (i386-mingw-nt5.1.2600)
 of 2008-01-30 on PRETEST
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4) --cflags -Ic:/gnuwin32/include'
 

Re: file-attributes returns negative integer for inode value

[Andreas Schwab]

"Drew Adams" <drew.adams@oracle.com> writes:

> No reliable recipe to reproduce, but for me, some directories give a
> negative inode number for file-attributes. For example:
>  
> M-x (file-attributes "c:/drews-lisp-20/Screenshots") gives:
>  
> (t 1 5 5 (18378 24192) (18123 40338) (18123 40337) 0
>  "drwxrwxrwx" nil -3082 240391127)
>  
> The inode value here is -3082.

And what's the real ino?

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

RE: file-attributes returns negative integer for inode value

[Drew Adams]

> > No reliable recipe to reproduce, but for me, some directories give a
> > negative inode number for file-attributes. For example:
> >  
> > M-x (file-attributes "c:/drews-lisp-20/Screenshots") gives:
> >  
> > (t 1 5 5 (18378 24192) (18123 40338) (18123 40337) 0
> >  "drwxrwxrwx" nil -3082 240391127)
> >  
> > The inode value here is -3082.
> 
> And what's the real ino?

Dunno. How do I tell that on Windows?

But I doubt you need that info to discover the problem, anyway. I suspect it
is a problem on Windows in the code that detects a too-large integer and
returns a cons in its place.

Re: file-attributes returns negative integer for inode value

[Eli Zaretskii]

> From: "Drew Adams" <drew.adams@oracle.com>
> Date: Sun, 2 Mar 2008 16:12:59 -0800
> Cc: emacs-pretest-bug@gnu.org
> 
> > > M-x (file-attributes "c:/drews-lisp-20/Screenshots") gives:
> > >  
> > > (t 1 5 5 (18378 24192) (18123 40338) (18123 40337) 0
> > >  "drwxrwxrwx" nil -3082 240391127)
> > >  
> > > The inode value here is -3082.
> > 
> > And what's the real ino?
> 
> Dunno. How do I tell that on Windows?

One way is to run "ls -i" on that file.  You will need ls.exe from the
GnuWin32 port of Coreutils.  Note that the w32 emulation of `stat' in
the Windows port of Emacs does not use the real inode value verbatim,
it mangles it with bit-shift and XOR operations.  This is because the
inode is a 48-bit value, while sys/stat.h on Windows says the inode is
a 16-bit field.

> But I doubt you need that info to discover the problem, anyway. I suspect it
> is a problem on Windows in the code that detects a too-large integer and
> returns a cons in its place.

The problem is a little bit different: obviously, a 16-bit value
cannot overflow ab EMACS_INT.  The problem is we don't keep the value
positive.  I will work on this soon.

Re: file-attributes returns negative integer for inode value

[Eli Zaretskii]

> Date: Mon, 03 Mar 2008 06:25:42 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: schwab@suse.de, emacs-pretest-bug@gnu.org
> 
> The problem is a little bit different: obviously, a 16-bit value
> cannot overflow ab EMACS_INT.  The problem is we don't keep the value
> positive.  I will work on this soon.

(For some value of "soon".)

Done.