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Series of operations needed to answer the questions os.access is not answering on windows:
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;
}