hi and thanks for the detailed bug report!

i think your suggestion for a fix is right, i'll fix this for the next release.

kjetil

On Thu, Mar 5, 2009 at 3:48 AM, <johansen_at_sun.com> wrote:
> I seem to have run afoul of a problem lurking within the pycurl
> easy handle's reset function.  If I reset an easy handle and then
> attempt to use it again, the code fails in weird ways.  In the
> particular case that I came across, calling multi.info_read() on a
> handle that has been reset leads to the following stack trace:
>
> $ ./reset.py http://www.google.com
> Recd 5665 bytes from http://www.google.com
>
> Traceback (most recent call last):
>  File "./reset.py", line 65, in ?
>    main()
>  File "./reset.py", line 37, in main
>    count, good, bad = cm.info_read()
> pycurl.error: (0, 'Unable to fetch curl handle from curl object')
>
> I'll attaching the test case.  It illustrates the problem with using
> reset().  If you uncomment the line that resets the easy handle, the
> program runs in a loop.  Otherwise, it dies with the above stack after
> it has been reset.
>
> The problem seems to be due to the fact that when a handle is reset,
> it's not re-configured the way a new handle is in pycurl.c do_curl_new().
>
> do_curl_reset() looks like this:
>
>        static PyObject*
>        do_curl_reset(CurlObject *self)
>        {
>            unsigned int i;
>
>            curl_easy_reset(self->handle);
>
>            /* Decref callbacks and file handles */
>            util_curl_xdecref(self, 4 | 8, self->handle);
>
>            /* Free all variables allocated by setopt */
>        #undef SFREE
>        #define SFREE(v)   if ((v) != NULL) (curl_formfree(v), (v) = NULL)
>            SFREE(self->httppost);
>        #undef SFREE
>        #define SFREE(v)   if ((v) != NULL) (curl_slist_free_all(v), (v) = NULL)
>            SFREE(self->httpheader);
>            SFREE(self->http200aliases);
>            SFREE(self->quote);
>            SFREE(self->postquote);
>            SFREE(self->prequote);
>        #undef SFREE
>
>            /* Last, free the options */
>            for (i = 0; i < OPTIONS_SIZE; i++) {
>                if (self->options[i] != NULL) {
>                    free(self->options[i]);
>                    self->options[i] = NULL;
>                }
>            }
>
>            return Py_None;
>        }
>
>
> It calls curl_easy_reset(), which resets the options configured on the
> easy handle.  It then invokes util_curl_xdecref with flags 4 | 8, that
> clear up some internal state maintained by pycurl.  Unfortunately, the
> handle never gets re-configured.
>
> The do_multi_info_read() has a portion that looks like this:
>
>        /* Fetch the curl object that corresponds to the curl handle in the mess
>        res = curl_easy_getinfo(msg->easy_handle, CURLINFO_PRIVATE, &co);
>        if (res != CURLE_OK || co == NULL) {
>            Py_DECREF(err_list);
>            Py_DECREF(ok_list);
>            CURLERROR_MSG("Unable to fetch curl handle from curl object");
>        }
>
> Here, if CURLINFO_PRIVATE can't be found, we die with the "Unable to
> fetch curl handle from curl object" message that was seen in the stack
> trace.  After the call to curl_easy_reset() the value for
> CURLOPT_PRIVATE has been erased.  The only routine that sets this value
> is do_curl_new():
>
>    [pycurl.c: line 777]
>
>    /* Set backreference */
>    res = curl_easy_setopt(self->handle, CURLOPT_PRIVATE, (char *) self);
>    if (res != CURLE_OK)
>        goto error;
>
> It looks to me that the code between lines 771 and 815 should be
> extracted into a separate routine that is invoked after a successful
> do_curl_new() as well as do_curl_reset().
>
> I'm attaching the test case as reset.py.  Any thoughts on this from the
> pycurl team?
>
> -j
>
> _______________________________________________
> http://cool.haxx.se/cgi-bin/mailman/listinfo/curl-and-python
>
>
_______________________________________________
http://cool.haxx.se/cgi-bin/mailman/listinfo/curl-and-python
Received on 2009-03-05