Re: [RFA] Fix cygwin compilation failure due to nameless LOAD_DLL_DEBUG_EVENT causes ntdll.dll to be missing

[Eli Zaretskii <eliz at gnu dot org>]

> Date: Wed, 18 Dec 2013 20:17:57 +0100
> From: Corinna Vinschen <vinschen@redhat.com>
> 
> > > I don't know, but I doubt it.  The filenames in case of calling the
> > > _wfopen functions are probably sent directly to the underlying WIn32
> > > functions.
> > 
> > I don't think they can do that, because it would mean that relative
> > file names, "../foo", etc. are forbidden for _wfopen.  The CRT
> > functions must go through file-name normalization, so unless they
> > detect \\?\ file names up front and refrain from any processing, the
> > long file names will not work, because the normalization routines are
> > where these limitations live, AFAIK.
> 
> There's a lot of theory here.  Did you actually *try* it?

No.  Who can afford to try everything, unless they are paying you to
do that?

> I just did:
> 
> ===========================================
> #include <stdio.h>
> #include <errno.h>
> 
> int main(void)
> {
>   FILE *fp;
> 
>   fp = _wfopen (L"\\\\?\\C:\\Windows\\System32\\ntdll.dll", L"r");
>   if (!fp)
>     printf ("_wfopen w/ long pathname fails, errno = %d\n", errno);
>   else
>     {
>       printf ("_wfopen w/ long pathname works\n");
>       fclose(fp);
>     }
>    return 0;
> }
> ===========================================

Thanks, that's good to know.  But that's just one CRT function.  There
are a gazillion of them, and I'm quite sure some use MAX_PATH of 260
internally.  Just grep the sources of the CRT functions.