Re: [boost] filesystem::is_directory return true when exception is disabled and this directory does't exist

From: Peter Dimov (pdimov_at_[hidden])
Date: 2004-10-11 15:02:55

Beman Dawes wrote:
> At 10:01 AM 10/11/2004, Liao Weijie wrote:
>> // the snip of code in filesystem::is_directory begin---
>>
>>      DWORD attributes = ::GetFileAttributesA(
>> ph.native_directory_string().c_str() );
>>      if ( attributes == 0xFFFFFFFF )
>>        boost::throw_exception( filesystem_error(
>>          "boost::filesystem::is_directory",
>>          ph, fs::detail::system_error_code() ) );
>>      return (attributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
>>
>> //-------------------------------------------------------end--
>>
>> When GetFileAttributesA failed but the exception is disabled,  the
>> (attributes & FILE_ATTRIBUTE_DIRECTORY)  will always be true.
>>
>> Is it a bug?
>
> No. It is undefined behavior for boost::throw_exception() to return.
>
> To quote the throw_exception() docs:
>
>      Callers of throw_exception are allowed to assume that the
>      function never returns; therefore, if the user-defined
>      throw_exception returns, the behavior is undefined.

It is definitely not a bug. However you might want to consider - purely as a 
QoI issue, of course - to return 'false' instead of 'true' when 
throw_exception returns. ;-)