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[cdt-dev] Re: [cdt-debug-dev] MI: obtaining GDB's stderr

Sounds like your output stream is not being flushed.  Try flushing it after
each write and see if that changes your output.

It could be possible as well that GDB is not flushing the stderr stream,
but that's probably less likely.

===========================

Chris Recoskie
Team Lead, IBM CDT Team
IBM Toronto
http://www.eclipse.org/cdt



                                                                           
             Derek Morris                                                  
             <dmsubs@consertum                                             
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             Sent by:                  CDT Debug developers list           
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             nces@xxxxxxxxxxx                                           cc 
                                                                           
                                                                   Subject 
             17/11/2006 10:58          Re: [cdt-debug-dev] MI: obtaining   
             AM                        GDB's stderr                        
                                                                           
                                                                           
             Please respond to                                             
                 CDT Debug                                                 
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             <cdt-debug-dev@ec                                             
                lipse.org>                                                 
                                                                           
                                                                           




Mikhail,

Yes, you are right, it doesn't close the stream.

I have now written a reader thread that sits on GDB's stderr and pumps to
System.out. It does nothing until GDB exits and then prints all of the data

written to stderr. That is, it is blocked on the first read of GDB's
stderr.

So, the data is being written to stderr, but for some reason, I am unable
to
read it immediately.

Any further ideas?

Thanks,

--
Derek


Mikhail Khodjaiants wrote:
> A short comment. Did you try to set a breakpoint in this code? If
> exitValue for some reason doesn't throw an exception (a bug in the
> spawner) and there is no error message the error stream will be closed,
> but the session will continue.
>
> -----Original Message-----
> From: cdt-debug-dev-bounces@xxxxxxxxxxx
> [mailto:cdt-debug-dev-bounces@xxxxxxxxxxx] On Behalf Of Mikhail
> Khodjaiants
> Sent: 17 November 2006 14:34
> To: CDT Debug developers list
> Subject: RE: [cdt-debug-dev] MI: obtaining GDB's stderr
>
> Derek,
>
> This code checks if the gdb process has terminated. "exitValue()"
> returns a value if the process has terminated, otherwise throws
> IllegalThreadStateException. The process can terminate at the startup
> for many reason. In this case this code reads the error message, closes
> the error stream and throws Miexception to inform the client.
> If the process is running (normal situation) this code does nothing
> (catch IllegalThreadStateException).
>
> Mikhail
>
> -----Original Message-----
> From: cdt-debug-dev-bounces@xxxxxxxxxxx
> [mailto:cdt-debug-dev-bounces@xxxxxxxxxxx] On Behalf Of Derek Morris
> Sent: 16 November 2006 14:37
> To: CDT Debug developers list
> Subject: Re: [cdt-debug-dev] MI: obtaining GDB's stderr
>
> Mikhail,
>
> I think I have found why I cannot get to GDB's stderr. In
> MISession#setup:
>
>            gdbProcess.exitValue();
>            InputStream err = gdbProcess.getErrorStream();
>            BufferedReader reader = new BufferedReader(new
> InputStreamReader(err));
>            String line = null;
>            try {
>                        line = reader.readLine();
>                        reader.close();
>            } catch (Exception e) {
>                        // the reader may throw a NPE.
>            }
>
> This is done before the txThread and rxThread are start()ed.
>
> So, it opens the error stream as a BufferedReader, reads and discards
> whatever it finds, and then closes it.
>
> Q: When the BufferedReader closes, will it also close the err
> InputStream? i.e.
> when i try to open the ErrorStream later on, will it always be empty?
>
> Q: Do you know why it might do this?
>
> Thanks,
>
> --
> Derek
>
>
> Mikhail Khodjaiants wrote:
>> Hi Derek,
>>
>> In most cases the process returned by "getGDBProcess" is not a process
>
>> that runs gdb. There is a class called Spawner that starts a gdb
> process
>> and creates the pipes for stdin, stdout and stderr. The Spawner's
> native
>> code is located in the "library" directory of the
>> org.eclipse.cdt.core.<os> plugins. It may be a bug, I don't know if we
>
>> have ever used the error stream from gdb.
>>
>> It would be very useful if you and other "monitor" users come up with
>> the requirements on how to improve the support for "monitor" in
> general.
>> My personal experience with it is very limited.
>>
>> Regards,
>> Mikhail
>>
>> -----Original Message-----
>> From: cdt-debug-dev-bounces@xxxxxxxxxxx
>> [mailto:cdt-debug-dev-bounces@xxxxxxxxxxx] On Behalf Of Derek Morris
>> Sent: 13 November 2006 16:59
>> To: CDT Debug developers list
>> Subject: [cdt-debug-dev] MI: obtaining GDB's stderr
>>
>> Hi,
>>
>> How can I get access to GDB's stderr? I am trying to obtain additional
>> (error) information that is returned from a "monitor" command.
>>
>> I am using the following code but reader.ready() always returns false.
>>
>> MIProcess gdbProcess = miSession.getGDBProcess(); InputStream err =
>> gdbProcess.getErrorStream(); BufferedReader reader = new
>> BufferedReader(new InputStreamReader(
>>                       err));
>> String line = null;
>> try {
>>           while (reader.ready()) {
>>                       line = reader.readLine();
>>                       errors.add(line) ;
>>           }
>>           reader.close();
>> } catch (Exception e) {
>>           e.printStackTrace() ;// the reader may throw a NPE.
>> }
>>
>> I know that data is being written to stderr - I just can't get it!
>>
>> TIA
>> --
>> Derek
>> _______________________________________________
>> cdt-debug-dev mailing list
>> cdt-debug-dev@xxxxxxxxxxx
>> https://dev.eclipse.org/mailman/listinfo/cdt-debug-dev
>>
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