[vbox-dev] Logging in Custom COM Implementations

Adam Pridgen adam.pridgen at thecoverofnight.com
Wed Oct 10 21:25:33 PDT 2012


First thank you to everyone who has been helpful so far.  Right now,
I am trying to figure out how to set-up logging for my custom interface.
I am still shaky about some aspects of the logging frame work
after reading the help page, postings on the mailing list, and some
of the source code in iprt/logging.h, and I have two questions:

1) How do I specify or enable logging for a function in the implementation
   of my custom COM interface?
2) What is a VBOX_LOG_FLAGS setting/configuration that I can use to capture
   *all* logging messages to "stderr"?  Using "VBOX_LOG=all" alone does not
   capture any of the messages in my COM interface or the added logging
   messages I added to parts of VB.

Below is an example to help conceptualize what I am trying to do in question 1
with a number of details omitted.  First, I have created an
implementation for a
COM interface, and DoFoo is a function that will be called via the VBoxManage

For the sake of the example, the implementation class exists in
src/VBox/Main/src-client/BarImpl.cpp, and the implementation makes calls
to the logging framework (similar to src/VBox/Main/src-client/ConsoleImp,
Console::PowerDown 2029:2030).  I have also used LogAlways for testing

Snippet from src/VBox/Main/src-client/BarImpl.cpp
// Bar implements the IBar interface, which is
// defined in the VirtualBox.xidl

    LogFlowThisFunc(("DoFoo is barring.\n"));
    LogAlways(("Bar addr for this: 0x%08x", this));
    AutoCaller autoCaller(this);
    HRESULT hrc = autoCaller.rc();
    Console::SafeVMPtrQuiet pVM (mParent);
    if (!pVM.isOk())
        return setError(VBOX_E_INVALID_VM_STATE, "Machine is not running");
    return hrc;

To enable logging and capture messages from this particular class, I set
my environment variables to the following:


When I attempt to use the above configuration to capture logging along with the
logged messages, I get the following error:

!!Assertion Failed!!
Expression: <none>
Location  : /some/path/vbox/src/VBox/Runtime/common/log/log.cpp(1711)
int RTLogFlags(PRTLOGGER, const char*)
Invalid flags! unknown instruction bar.e.f
Trace/breakpoint trap (core dumped)

Sorry for the long email, and please let me know if more details are needed
to help answer this question.  Thanks,

-- Adam

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