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WindowsApi:GetFileSecurity

How to Check Access Rights 

bool CanAccessFolder( LPCTSTR folderName, DWORD genericAccessRights )
{
    bool bRet = false;
    DWORD length = 0;
    if (!::GetFileSecurity( folderName, OWNER_SECURITY_INFORMATION | GROUP_SECURITY_INFORMATION 
            | DACL_SECURITY_INFORMATION, NULL, NULL, &length ) && 
            ERROR_INSUFFICIENT_BUFFER == ::GetLastError()) {
        PSECURITY_DESCRIPTOR security = static_cast< PSECURITY_DESCRIPTOR >( ::malloc( length ) );
        if (security && ::GetFileSecurity( folderName, OWNER_SECURITY_INFORMATION | GROUP_SECURITY_INFORMATION
                            | DACL_SECURITY_INFORMATION, security, length, &length )) {
            HANDLE hToken = NULL;
            if (::OpenProcessToken( ::GetCurrentProcess(), TOKEN_IMPERSONATE | TOKEN_QUERY | 
                    TOKEN_DUPLICATE | STANDARD_RIGHTS_READ, &hToken )) {
                HANDLE hImpersonatedToken = NULL;
                if (::DuplicateToken( hToken, SecurityImpersonation, &hImpersonatedToken )) {
                    GENERIC_MAPPING mapping = { 0xFFFFFFFF };
                    PRIVILEGE_SET privileges = { 0 };
                    DWORD grantedAccess = 0, privilegesLength = sizeof( privileges );
                    BOOL result = FALSE;

                    mapping.GenericRead = FILE_GENERIC_READ;
                    mapping.GenericWrite = FILE_GENERIC_WRITE;
                    mapping.GenericExecute = FILE_GENERIC_EXECUTE;
                    mapping.GenericAll = FILE_ALL_ACCESS;

                    ::MapGenericMask( &genericAccessRights, &mapping );
                    if (::AccessCheck( security, hImpersonatedToken, genericAccessRights, 
                            &mapping, &privileges, &privilegesLength, &grantedAccess, &result )) {
                        bRet = (result == TRUE);
                    }
                    ::CloseHandle( hImpersonatedToken );
                }
                ::CloseHandle( hToken );
            }
            ::free( security );
        }
    }

    return bRet;
}

You use the function by passing in the path to a file or folder, and one or more of the GENERIC flags, like this: 

if (CanAccessFolder( TEXT( "C:\\Users\\" ), GENERIC_WRITE )) {}
if (CanAccessFolder( TEXT( "C:\\" ), GENERIC_READ | GENERIC_WRITE )) {}

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