Re: Segfault in _this()

[Bowie Owens <bowie owens csiro au>]

Hi Johan,

Please try inspecting the arguments passed to 
ORBit_POA_activate_object() when it seg. faults. See if there is 
anything odd going on there. Posting a full backtrace with prints of 
each argument (and prints of the dereferenced value for pointers) might 
help.

One other thing, I think it is possible for orbitcpp to seg. fault if 
the library and client/server code are compiled with differing CXXFLAGS. 
My guess is something to do with optimisations and inlining, but I'm not 
quite sure. Please make sure you are building both your code and 
orbitcpp with CXXFLAGS=-g.

Johan Cronje wrote:

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> On Friday 01 August 2003 01:47, Bowie Owens wrote:
>  
>
> > Hi Johan,
> >
> > As for where to look, please try and determine which memory reference
> > caused the seg. fault. Was the rootPOA pointer null? Was the method
> > invoked on a null pointer (null this pointer)? Was the object the method
> > was invoked on deleted prior to the method call? Was the seg. fault
> > inside one the calls to activate_object or servant_to_id?
> >
> >    
>
> This is the new generated _this() method that 1.3.6 gives me (-cpp-skels.cpp 
> file). I have added the cout statements for debugging purposes.
>
> 1 ::sdr_corba::sdr_subcontroller_ptr POA_sdr_corba::sdr_subcontroller::_this()
> 2 {
> 3    cout << "blah\n";
> 4    PortableServer::POA_var rootPOA = _default_POA ();
> 5    cout << "blah 1\n";
> 6    CORBA::Object_var object = rootPOA->servant_to_reference (this);
> 7    cout << "blah 2\n";
> 8    return ::_orbitcpp::stub::sdr_corba::sdr_subcontroller::_orbitcpp_wrap
> 9    (object->_orbitcpp_cobj (), true);
> 10 }
>
> Now, the program segfaults between blah1 and blah2, indicating an error in
> line 6. The output of gdb is as follows:
>
> (gdb) run
> Starting program: /home/jcronje/SDR/devel/corbasdr/sdr_corba
> [New Thread 16384 (LWP 29450)]
> ORB_init
> orb->resolve_initial_references
> _narrow
> rootPOA->the_POAManager
> mgr->activate
> POA_sdr_corba_sdr_subcontroller__init (Called by 
> ::POA_sdr_corba::sdr_subcontroller::sdr_subcontroller)
> servant created
> Test Class 
> blah
> blah 1
>
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 16384 (LWP 29450)]
> 0x4006d346 in ORBit_POA_activate_object () from /usr/lib/libORBit-2.so.0
>
> Does this mean that my rootPOA pointer is null? If so, how do I fix it?
>
> Also find attached my main server implementation file, sdr_corba.cpp.
>
> Any help or direction will be greatly appreciated.
>
> Thank you
> try
> Johan
> - -- 
>
> - ---------------------------------------------------------------
> "There is beauty in simplicity"		-- Johan Cronje
> - ---------------------------------------------------------------
> Johan Cronje
> Digital Signal Processing / Telecommunications Group
> Electrical and Electronic Engineering Department
> University of Stellenbosch
> http://www.dsp.sun.ac.za/~jcronje
> GNUPG Key: http://www.dsp.sun.ac.za/~jcronje/jcronje.asc
> - ---------------------------------------------------------------
>
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> ------------------------------------------------------------------------
>
> /** $Id$
> * @file sdr_corba.cpp
> * @brief SDR CORBA ORBit Implementation
> * @author Johan Cronjé
> * @date 29/05/2003 14:53
> */
>
> #include <string>
> #include "sdr_corba.h"
> #include "sdr_corba-cpp.h"
> #include "sdr_corba_impl.h"
> #include <iostream>
> #include <linc/linc.h>
>
> using namespace std;
> using namespace POA_sdr_corba;
> using namespace _orbitcpp;
> using namespace sdr_corba;
> //using namespace sdr_base_classes;
>
> void POA_sdr_corba_sdr_subcontroller__init(PortableServer_Servant     servant,
>                                           CORBA_Environment *        ev)
> {
>   cout << "POA_sdr_corba_sdr_subcontroller__init" <<
>    " (Called by ::POA_sdr_corba::sdr_subcontroller::sdr_subcontroller)\n";
> }
>
> void POA_sdr_corba_sdr_subcontroller__fini(PortableServer_Servant     servant,
>                                           CORBA_Environment *        ev)
> {
>   cout << "Sukkel jy lekker? fini\n";
> }
>
> sdr_corba_attributes_list* 
> sdr_corba_sdr_subcontroller_return_attributes(sdr_corba_sdr_subcontroller _obj,
>                                              CORBA_Environment * ev)
> {
>   cout << "Sukkel jy lekker? 34 - 39\n";
> }
>
> CORBA_float 
> sdr_corba_sdr_subcontroller_return_attribute_value(sdr_corba_sdr_subcontroller _obj,
>                                                   const CORBA_char * attrib_c,
>                                                   CORBA_Environment * ev)
> {
>   cout << "Sukkel jy lekker? 41-47\n";
> }
>
> void sdr_corba_sdr_subcontroller_change_attribute_value(sdr_corba_sdr_subcontroller _obj,
>                                                        const CORBA_char * attribute_name,
>                                                        const CORBA_char * attribute_value,
>                                                        CORBA_Environment * ev)
>       {
>         cout << "Sukkel jy lekker? 49-55\n";
>       }
>
> sdr_corba_component_name
> sdr_corba_sdr_subcontroller_return_comptryonent_name(sdr_corba_sdr_subcontroller _obj,
>                                                  CORBA_Environment* ev)
> {
>   cout << "Sukkel jy lekker? 57-62\n";
> }
>
>
> int main (int argc, char* argv[])
> {
>   // Initialize the CORBA orb
>   CORBA::ORB_var orb = CORBA::ORB_init (argc, argv);
>
>   cout << "ORB_init\n";
>   // Get the root POA
>   CORBA::Object_var pfobj = orb->resolve_initial_references("RootPOA");
>   cout << "orb->resolve_initial_references\n";   
>   PortableServer::POA_var rootPOA =
>        PortableServer::POA::_narrow(pfobj);
>   cout << "_narrow\n";
>   // Activate the root POA's manager
>   PortableServer::POAManager_var mgr = rootPOA->the_POAManager();
>   cout << "rootPOA->the_POAManager\n";   
>   mgr->activate();
>   cout << "mgr->activate\n";
>   // Create a Servant and explicitly create a CORBA object
>   sdr_corba::sdr_corba_impl servant;
>   cout << "servant created\n";  
>   cout << servant.return_component_name() << endl;
>   CORBA::Object_var object = servant._this(); 
>   cout << "object = servant._this\n";
>   // Here we get the IOR for the Hello server object.
>   // Our "client" will use the IOR to find the object to connect to 
>   CORBA::String_var ref = orb->object_to_string( object );
>
>   // print out the IOR
>   cout << ref << endl;
>
>   // run the server event loop
>   orb->run();
>
> }
>  


--
Bowie Owens

CSIRO Mathematical & Information Sciences
phone  : +61 3 9545 8055
fax    : +61 3 9545 8080
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email  : Bowie Owens csiro au