No effect of SE_BACKUP_NAME privilege on cygwin?

[Christian Franke]

Enabling SE_BACKUP_NAME has no effect for cygwin programs.
The attached program demonstrates the issue.
It retrieves the attributes of a normally inaccessible file without and 
with SE_BACKUP_NAME.
(The file should be present on XP with C:\ as system drive)

If compiled with "-mno-cygwin" and running as admin on XP Prof, the 
second access succeeds as expected:

GetFileAttributes failed: 5
SeBackupPrivilege enabled!
GetFileAttributes = 0x0026

But if running as a cygwin program on 1.5.19, the result is:

GetFileAttributes failed: 5
SeBackupPrivilege enabled!
GetFileAttributes failed: 5

The privilege can be enabled, but has no effect - bug or feature ?-)

Thanks for any help.

Christian

#include <windows.h>
#include <stdio.h>

static void Check()
{
        DWORD attr = GetFileAttributes("C:/System Volume 
Information/MountPointManagerRemoteDatabase");
        if (attr == ~(DWORD)0)
                printf("GetFileAttributes failed: %ld\n", GetLastError());
        else
                printf("GetFileAttributes = 0x%04lx\n", attr); // Usually 
0x0026, Archive|System|Hidden
}

static bool GetBackupPrivil()
{
        HANDLE t;
        if(!OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES, &t)) 
{
                printf("OpenProcessToken failed: %ld\n", GetLastError()); 
return false;
        }
        TOKEN_PRIVILEGES tp;
        if(!LookupPrivilegeValue(NULL, SE_BACKUP_NAME, &tp.Privileges[0].Luid)) 
{
                printf("LookupPrivilegeValue failed: %ld\n", GetLastError()); 
return false;
        }
        tp.PrivilegeCount           = 1;
        tp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
        AdjustTokenPrivileges(t, FALSE, &tp, 0, NULL, NULL);
        if (GetLastError() != ERROR_SUCCESS) {
                printf("AdjustTokenPrivileges failed: %ld\n", GetLastError()); 
return false;
        }
        CloseHandle(t);
        printf(SE_BACKUP_NAME" enabled!\n");
        return true;
}

main()
{
        Check();

        if (!GetBackupPrivil())
                return 1;

        Check();
        return 0;
}

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