Problems with thread state

[Martin Sjögren]

On Tue, Jul 03, 2001 at 03:32:08PM -0000, Donn Cave wrote:
> Quoth Martin Sjgren <martin at strakt.com>:
> 
> | Seeing as a call to SSL_connect() might block, I surrounded the call to it
> | by Py_BEGIN_ALLOW_THREADS and Py_END_ALLOW_THREADS. I also have a wrapper
> | callback for verification (i.e. I plug my callback into OpenSSL and it
> | calls a Python callback residing in a Context object)... Here's my
> | problem: When I call PyEval_CallObject() in my wrapper callback, python
> | segfaults! Some poking around with gdb shows that somewhere, before
> | PyFrame_New() is called to execute the Python callback in,
> | PyThreadState_Get() returns NULL!
> 
> Prior to PyEval_CallObject(), you need to get back in line for the
> Python thread you released with Py_BEGIN_ALLOW_THREADS.  I do that
> with PyEval_AcquireThread(PyThreadState *), and then after the
> callback, PyEval_ReleaseThread(PyThreadState *).  How do you get
> the thread state?  Not the way I do, I reckon, so I will leave
> that to you.

This is how I do it, in my MySSL_Connection_connect()

    if (PySocketSock_connect(self->socket, args) == NULL)
        return NULL;
    setup_ssl(self); // creates a BIO and some stuff
    Py_BEGIN_ALLOW_THREADS
    ret = SSL_connect(self->ssl);
    Py_END_ALLOW_THREADS
    // handle ret, etc

But... SSL_connect may call a callback I've set, for verification
purposes. This function looks somewhat like this:

    // find context and certificate and stuff
    argv = Py_BuildValue(...);
    ret = PyEval_CallObject(ctx->verify_callback, argv);
    Py_DECREF(argv);
    // handle ret, etc

and this is where it crashes... Should I put in a PyThreadState pointer in
my ctx objects that I set instead of using BEGIN_ALLOW_THREADS, so I can
release and re-acquire around the CallObject?

Thanks a lot for your help

-- 
Martin Sjögren
  martin at strakt.com              ICQ : 41245059
  Phone: +46 (0)31 405242        Cell: +46 (0)739 169191
  GPG key: http://www.strakt.com/~martin/gpg.html
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