Subject: Re: bug#10733: 24.0.93; w32 file truncation

From: Óscar Fuentes <[email-masked]>
Date: Mon, 06 Feb 2012 06:25:32 +0100

Eli Zaretskii <[email-masked]> writes:

[snip]

> Emacs on Windows doesn't support symlinks; they are new with Vista and
> Windows 7.  Someone needs to write the code to support that, before
> this can be considered a bug (as opposed to a feature request).
>
> What you describe seems to indicate that insert-file-contents only
> reads the first 64KB portion of the file, and then bails out.  Running
> Emacs under debugger and reporting where it bails out of the reading
> loop might help coming up with some band-aid solution.  But full
> support of symlink requires specific support code, that just isn't
> there at this time.

NTFS symlinks are transparent to applications. Emacs doesn't need to
know that it is accessing a symlink to correctly read and save the file.

I bet it is a bug on the CRT (the stat call that retrieves the file
size, to be precise). Maybe it is a MinGW thing. It would be interesting
to hear reports from people using an Emacs compiled with a modern
version of Visual Studio, or even know if people using the most recent
MinGW CRT release can duplicate the problem.

This is a very serious bug (potential data loss). I'll put this on my
TODO list and hopefully run a debug session on a Windows 7 machine next
week. Meanwhile, if anyone can provide the info mentioned on the
previous paragraph, it would be helpful.