Race condition in libsvn_client code? (Was: svn commit: r1079508 ...)

[Tweaking Subject: for (hopefully) additional visibility.]

On 03/15/2011 09:15 AM, Daniel Shahaf wrote:
> C. Michael Pilato wrote on Tue, Mar 15, 2011 at 09:05:56 -0400:
>> On 03/15/2011 12:34 AM, Daniel Shahaf wrote:
>>> cmpilato_at_apache.org wrote on Tue, Mar 08, 2011 at 20:05:51 -0000:
>>>> Author: cmpilato
>>>> Date: Tue Mar 8 20:05:50 2011
>>>> New Revision: 1079508
>>
>> [...]
>>
>>>> svn_client_commit4(svn_commit_info_t **commit_info_p,
>>>> const apr_array_header_t *targets,
>>
>> [...]
>>
>>>> + /* Ensure that the original notification system is in place. */
>>>> + ctx->notify_func2 = notify_baton.orig_notify_func2;
>>>> + ctx->notify_baton2 = notify_baton.orig_notify_baton2;
>>>> +
>>>
>>> This is actually a race condition, isn't it? (for clients that call the
>>> deprecated API while using CTX->notify_func2 in another thread (in the
>>> same or another API))
>>>
>>> (Okay, so maybe we'll just let it live on. Presumably N other
>>> deprecated wrappers do this too.)
>>
>> I hadn't considered that. We do alot of pointer swaps like this up in the
>> command-line client code itself, but that's a bit different than doing so
>> down in the libsvn_client library as in this case. There is one prior
>> instance of us doing this kind of swap inside the libsvn_client library: in
>> libsvn_client/copy.c:repos_to_wc_copy_single(). But I'd prefer mere
>> precedent not to be our reason for allowing badness to persist in the codebase.
>>
>> Got suggestions?
>
> Would this work? ---
>
> svn_client_ctx_t ctx2 = *ctx;
> ctx2.notify_func2 = notify_baton.orig_notify_func2;
> ctx2.notify_baton2 = notify_baton.orig_notify_baton2;
> svn_client_commit5(ctx=&ctx2);

-- 
C. Michael Pilato <cmpilato_at_collab.net>
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