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

Corinna Vinschen
2013-12-18T19:18:01Z

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On Dec 18 20:18, Eli Zaretskii wrote:
> > Date: Wed, 18 Dec 2013 18:31:55 +0100
> > From: Corinna Vinschen <vinschen@redhat.com>
> >
> > > So lifting the 260-char limit means both go to Unicode _and_ use the
> > > \\?\ format of file names, is that right?
> >
> > Right.
> >
> > > If so, it probably means
> > > that CRT functions that accept wchar_t arrays as file names (_wfopen
> > > etc.) cannot be used with such long file names, and one needs to call
> > > the Win32 APIs directly. Correct?
> >
> > 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? 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;
}
===========================================

Corinna

--
Corinna Vinschen
Cygwin Maintainer
Red Hat

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