[Gambas-user] gb.debug: Unable to open fifo

[Benoît Minisini]

Le 24/05/2017 à 22:43, T Lee Davidson a écrit :
> On 05/23/2017 06:07 PM, Tobias Boege wrote:
>> On Tue, 23 May 2017, T Lee Davidson wrote:
>>> Hello folks,
>>>
>>> I am trying to see if gb.debug will help me diagnose why HttpClient does not properly expose redirect response codes on my
>>> system (and reportedly Tobi's system) while it does so correctly on Benoît's system.
>>>
>>> However, the documentation for gb.debug is so sparse that I am having to experiment and, of course, having a problem.
>>>
>>> With the following command-line application code (using the gb.debug component):
>>> ' Gambas module file
>>>
>>> Public Sub Main()
>>>
>>>      Dim sName As String
>>>
>>>      sName = Debug.Begin()
>>>      Print sName
>>>      Debug.Start ' Unable to open fifo
>>>      Debug.Write("Hello world")
>>>      Debug.Stop
>>>      Debug.End
>>>
>>> End
>>>
>>> Public Sub Debug_Read(Data As String)
>>>
>>>      Print Data
>>>
>>> End
>>> ' End Gambas module file
>>>
>>> Debug.Start causes an exception: "Unable to open fifo". By looking in /tmp/gambas.1000/, I can see that the process id input and
>>> output pipes are successfully created with the correct file mode permissions (600) for my user as owner. But, the Start
>>> procedure apparently cannot open the output fifo (ref.
>>> https://sourceforge.net/p/gambas/code/HEAD/tree/gambas/trunk/main/lib/debug/CDebug.c).
>>>
>>> Am I attempting to use this component incorrectly?
>>>
>>
>> I think you're attempting to use the wrong component. gb.debug is meant for
>> the Gambas IDE to debug a Gambas project. You can look at the source code of
>> the IDE to try to figure out how to use it. I don't understand its protocol
>> at all. My wild guess is that your error comes from not having started the
>> application in debug mode (gbx3 -g)?
>>
>> In any case, I doubt debugging your *Gambas* code will give you any insight
>> into the gb.net.curl issue, as gb.net.curl and curl itself are not written
>> in Gambas.
>>
>> Regards,
>> Tobi
>>
> 
> Thank you for your response, Tobi.
> 
> I was actually running the application from within the IDE. Making an executable and then executing that with "gbx3 -g" resulted in:
> Welcome to the Gambas debugger.
> *[15488]                ?
> 
> followed by the greater-than symbol (>) which is obviously an input prompt. "OK, now what?" (Since I find no documentation
> for gbx3.)
> 
> Typing "help" at the prompt gave, "W       Unknown command: help". Hmmm ... maybe "step"? Ooo, that does something:
> 
> > step
> *[15488]                Main.Main.7     sName   S: s:
> > step
> *[15488]                Main.Main.8     sName   S: s:
> 
> > step
> 15488
> 
> *[15488]                Main.Main.9     sName   S: s:
> 
> > step
> *[15488]        Unable to open fifo     Main.Main.9     sName   S: s:
> 
> And I discovered that there is a "quit" command that works too.
> 
> Given that Debug.Begin creates pipe files named according to the current process' ID (PID) and that the IDE and the executable
> would always have different PIDs, I cannot fathom how the two could "talk". Nor do I, at this point, have any clue whatsoever
> how the gb.debug component is intended to be used.
> 
> I was hoping it might give me access to the running properties of the HttpClient object. But, I am not going to spend any more
> time on this groping in the dark. I'll just have to look in a different direction, or wait until the issue somehow magically
> fixes itself.
> 
> 

You have no need of the internal debugger interface, as everything you 
can do with it, you can do the same from the IDE.

You don't have access to the internal of the HttpClient object, unless 
you debug the interpreter with gdb (it's written in C). But you can set 
the Debug property of the object to get the debugging messages of the 
libcurl library, HttpClient being just a thin wrapper on libcurl.

Regards,

-- 
Benoît Minisini