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Re: FindFirstFile fails for some network directories
- From: Orgad Shaneh <orgads at gmail dot com>
- To: cygwin at cygwin dot com
- Date: Wed, 19 Aug 2015 08:46:01 +0300
- Subject: Re: FindFirstFile fails for some network directories
- Authentication-results: sourceware.org; auth=none
- References: <CAGHpTBKEWFa8M1KN6_vqrBT6WOjVpmOCUqP-LHBYK=FApg2fJg at mail dot gmail dot com>
On Mon, Aug 17, 2015 at 3:03 PM, Orgad Shaneh <email@example.com> wrote:
> I have 2 network shares with similar contents:
> Trying to list all the files within these directories using Ruby
> succeeds for netapp1, but fails for aclnas01.
> The failing ruby command is:
> ruby -e "print Dir.glob('//aclnas01/versions/CompilationResults/*')"
> The exact same command succeeds when executed from a normal command
> prompt, or when the directory is on netapp1 (on both shells).
> After debugging Ruby, I found out that FindFirstFile returns an
> INVALID_HANDLE when invoked from cygwin environment.
> The following application succeeds on command prompt and fails on cygwin:
> #include <stdio.h>
> #include <windows.h>
> int main()
> const TCHAR *aclnas = TEXT("//aclnas01/versions/CompilationResults");
> const TCHAR *netapp = TEXT("//netapp1/CM/CompilationResults");
> WIN32_FIND_DATA fd;
> printf("%d\n", FindFirstFile(aclnas, &fd) !=
> INVALID_HANDLE_VALUE); // Fails on cygwin
> printf("%d\n", FindFirstFile(netapp, &fd) !=
> INVALID_HANDLE_VALUE); // Always succeeds
> return 0;
> Output on cmd is 1 1, on cygwin it is 0 1.
> Process Monitor shows that when executed from cygwin, CreateFile is
> called with Open for Backup flag. I can't say for sure if this causes
> the failure, but that's the only difference I could find between these
> This bug was previously reported on github/msys2, but it wasn't solved.
> I only have read access to these servers, but I might have cooperation
> of the sys admin (can't promise though).
> Any help will be appreciated.
> - Orgad
>  https://github.com/Alexpux/MSYS2-packages/issues/242
Using Wireshark, I discovered that aclnas01 uses SMB, while netapp1 uses SMB2.
For some reason, when executed from command prompt, a FIND_FIRST2
request is sent and the server replies, while with cygwin a "NT Create
AndX" request is sent and denied.
To minimize the captured packets, I executed the application twice,
and captured only the second execution (to avoid session initiation).
Working capture: https://gist.github.com/orgads/d2681881668afb9cb08f
Failing capture: https://gist.github.com/orgads/4f0ea2b26cfd64f4353d
Does cygwin implement SMB on its own, or is this difference a
side-effect of the "Backup Intent" flag?
Problem reports: http://cygwin.com/problems.html
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