Accessing UNIX FileDescriptor id without reflection

[Remi Forax]

----- Mail original -----
> De: "Roger Riggs" <Roger.Riggs at Oracle.com>
> À: core-libs-dev at openjdk.java.net
> Envoyé: Lundi 8 Mai 2017 17:45:25
> Objet: Re: Accessing UNIX FileDescriptor id without reflection

> Hi,
> 
> I would be very cautious about giving out fds for arbitrary FileDescriptors.
> With concurrency and threading, how do you make sure that it does not
> not get closed
> and someone's code still has the fd and uses it later?  Or worse yet,
> the fd gets re-used
> and then it is possible to operate on the wrong file.
> Quite a bit of implementation code assumes it has complete control over
> the lifecycle of
> the FileDescriptor.  Exposing the raw FD breaks the encapsulation.
> 
> As Rémi suggests, passing the FileDescriptor to native will at least
> maintain the current
> encapsulation.

s/Rémi/Peter
Peter is right, i'm wrong :)

> 
> Roger

Rémi

> 
> 
> On 5/8/2017 10:14 AM, Remi Forax wrote:
>> I agree that a method getFd should be great, we will need this kind of value if
>> we want to use Panama.
>>
>> Did you try to serializing the FileDescriptor in memory and extract the int
>> corresponding to the file descriptor ?
>>
>> cheers,
>> Rémi
>>
>> ----- Mail original -----
>>> De: "Enrico Olivelli" <eolivelli at gmail.com>
>>> À: core-libs-dev at openjdk.java.net
>>> Envoyé: Lundi 8 Mai 2017 15:16:24
>>> Objet: Accessing UNIX FileDescriptor id without reflection
>>> Hi,
>>> I am trying to port a project (Apache BookKeeper) to Java9, actually
>>> this code uses reflection in order to access the 'fd' field of the
>>> FileDescriptor class.
>>>
>>> We have to access that ID in order to call low level native functions
>>>
>>> See
>>> https://github.com/apache/bookkeeper/blob/master/bookkeeper-server/src/main/java/org/apache/bookkeeper/util/NativeIO.java
>>> # getSysFileDescriptor
>>>
>>> Is there any way to access the FD handle without using reflection ?
>>> If not, is it possibile to enhance the FileDescriptor API in order to
>>> given access to the internal "fd" field ?
>>>
>>> Thank you
>>>
> >> Enrico Olivelli