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Date: Mon, 22 Nov 2010 11:57:46 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: 1.7.8: files exist but can not be read
Message-ID: <20101122105746.GQ18309@calimero.vinschen.de>
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On Nov 20 22:17, A.R. Burgers wrote:
>  LS,
> 
> on 1.7.8 files the contents of a file on a netapp share can not be read by all programs.
> [...]
> #! /bin/sh
> 
> uname -a
> zz=/shares/g_zon_software/cygwin17
> ls -l $zz/bug.txt
> rm -f $zz/bug.txt
> cat << HERE > $zz/bug.txt
> line 1
> HERE
> ls -l $zz/bug.txt
> cat $zz/bug.txt
> file $zz/bug.txt
> cat /etc/fstab | grep g_zon_software
> mount -m | grep 'share.*g_zon_software'

> CYGWIN_NT-5.1 P4114 1.7.8s(0.233/5/3) 20101118 15:52:06 i686 Cygwin
> -rw-r--r-- 1 burgers Domain Users 0 2010-11-19 13:35 /shares/g_zon_software/cygwin17/bug.txt
> -rw-r--r-- 1 burgers Domain Users 0 2010-11-19 13:36 /shares/g_zon_software/cygwin17/bug.txt
> line 1
> /shares/g_zon_software/cygwin17/bug.txt: empty

So it appears that you *can* read the files after all, but the stat
function returns a file size of 0, right?  So all tools which test
the file size before opening a file will fail.

The question now is, why does it return 0.  What has changed in Cygwin
is that a core function now uses the FileNetworkOpenInformation class to
fetch file information.  Maybe that's not quite correctly implemented on
Netapps?

Can you please give the attached testcase a try?  Link it against ntdll
and use the DOS path to the file as parameter, like this:

  $ gcc -g -o ntqueryfile ntqueryfile.c -lntdll
  $ ./ntqueryfile \\\\nas01\\g_zon_software\\cygwin17\\bug.txt

Please paste the output into your reply.


Thanks,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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Content-Type: text/x-c++src; charset=utf-8
Content-Disposition: attachment; filename="ntqueryfile.c"

#include <stdio.h>
#include <ddk/ntifs.h>
#include <sys/cygwin.h>

BOOL NTAPI RtlCreateUnicodeStringFromAsciiz (PUNICODE_STRING, PCSTR);

int
main (int argc, char **argv)
{
  UNICODE_STRING wpath;
  UNICODE_STRING upath;
  HANDLE h;
  OBJECT_ATTRIBUTES attr;
  IO_STATUS_BLOCK io;
  NTSTATUS status;
  FILE_NETWORK_OPEN_INFORMATION fnoi;
  FILE_STANDARD_INFORMATION fsi;
  
  if (argc < 2)
    {
      fprintf (stderr, "usage: %s DOS-PATH\n", argv[0]);
      return 1;
    }
  if (!RtlCreateUnicodeStringFromAsciiz (&wpath, argv[1]))
    {
      fprintf (stderr, "RtlCreateUnicodeStringFromAsciiz failed\n");
      return 1;
    }
  if (!RtlDosPathNameToNtPathName_U (wpath.Buffer, &upath, NULL, NULL))
    {
      fprintf (stderr, "RtlDosPathNameToNtPathName_U failed\n");
      RtlFreeUnicodeString (&wpath);
      return 1;
    }
  InitializeObjectAttributes (&attr, &upath, 0, NULL, NULL);
  status = NtOpenFile (&h, READ_CONTROL | FILE_READ_ATTRIBUTES, &attr, &io,
		       FILE_SHARE_VALID_FLAGS,
		       FILE_OPEN_REPARSE_POINT | FILE_OPEN_FOR_BACKUP_INTENT);
  if (!NT_SUCCESS (status))
    {
      fprintf (stderr, "NtOpenFile: 0x%08lX\n", status);
      return 1;
    }
  status = NtQueryInformationFile (h, &io, &fnoi, sizeof fnoi,
				   FileNetworkOpenInformation);
  if (!NT_SUCCESS (status))
    fprintf (stderr, "NtQueryInformationFile(FNOI): 0x%08lx\n", status);
  else
    {
      printf ("fnoi.AllocationSize %lld\n", fnoi.AllocationSize.QuadPart);
      printf ("fnoi.EndOfFile      %lld\n", fnoi.EndOfFile.QuadPart);
    }
  status = NtQueryInformationFile (h, &io, &fsi, sizeof fsi,
				   FileStandardInformation);
  if (!NT_SUCCESS (status))
    fprintf (stderr, "NtQueryInformationFile(FSI): 0x%08lx\n", status);
  else
    {
      printf (" fsi.AllocationSize %lld\n", fsi.AllocationSize.QuadPart);
      printf (" fsi.EndOfFile      %lld\n", fsi.EndOfFile.QuadPart);
    }
  NtClose (h);
  return 0;
}


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