Problem with Win32 WNet APIs and NFS paths - winapi

Question

I am running on a Win2K8R2 system that has Microsoft's NFS client installed in addition to the Windows CIFS client.
Given a UNC path (which the NFS client does support with caveats) I need to be able to tell if operations on the path would be handled by the CIFS or NFS client. WNetGetResourceInformation() would seem to provide this, but I have not been able to get it to work when the UNC path is to an NFS server.
Sample code:
int GetResourceInformation(TCHAR* path, void* buffer, DWORD* size)
{
TCHAR* p = NULL;
NETRESOURCE nr;
memset(&nr, 0, sizeof(nr));
nr.lpRemoteName = path;
DWORD dwRetVal = WNetGetResourceInformation(&nr, buffer, size, &p);
if(dwRetVal == NO_ERROR)
{
NETRESOURCE* tmp = (NETRESOURCE*)buffer;
wprintf(L"%s provider=%s system=%s\n", path, tmp->lpProvider, (p == NULL) ? L"<null>" : p);
}
else
{
wprintf(L"WNetGetResourceInformation failed for %s with error: %u\n", path, dwRetVal);
}
return dwRetVal;
}
I have also tried filling in the NETRESOURCE lpProvider and/or dwType fields as suggested in the doc but with no change in behavior.
If I pass the function a CIFS UNC path it succeeds. If I pass it an NFS UNC path it fails with error 487 "Attempt to access invalid address.". I also tried passing the native NFS path style hostname:/export/file but this fails with error 67 "The network name cannot be found."
I found the following sample for using WNetAddConnection2() with NFS but this code also fails for me with error 50 "The request is not supported". I can successfully mount the export using either "net use" command or the NFS-specific mount.exe tool provided by Microsoft.
Finally, WNetOpenEnum/WNetEnumResource does not return any NFS provider information for me or even show any connected drives that I have mapped via "net use" or mount.exe.
My general question is, has anyone had better success using the the WNet APIs with the NFS provider? Specifically, is there some mechanism I can use to determine the provider for a remote path?

Answer 1

Are you building as x86 or x64? It looks like the WNet* API's don't work correctly for NFS shares from an x86 process under WOW64. You can see this without writing code - if you have an NFS share mounted, "C:\windows\system32\net use" will show it, where "C:\windows\syswow64\net use" will not. Filesystem access seems OK the 32-bit process, but none of the APIs work.
Even built as x64, using a NULL lpProvider is inconsistent for me. Half the time it doesn't work, the other half it waits about 5 seconds before returning.
Calling WNetGetResourceInformation twice, once with a lpProvider of "NFS Network" and once with "Microsoft Windows Network" works consistently and returns instantly.