Re: PL/Python error checking - Mailing list pgsql-patches

From Bruce Momjian
Subject Re: PL/Python error checking
Date
Msg-id 200507100458.j6A4wO709403@candle.pha.pa.us
Whole thread Raw
In response to PL/Python error checking  (Michael Fuhr <mike@fuhr.org>)
Responses Re: PL/Python error checking
List pgsql-patches
Michael Fuhr wrote:
> This patch addresses the problem mentioned in the "process crash
> when a plpython function returns unicode" thread:
>
> http://archives.postgresql.org/pgsql-bugs/2005-06/msg00105.php
>
> In several places PL/Python was calling PyObject_Str() and then
> PyString_AsString() without checking if the former had returned
> NULL to indicate an error.  PyString_AsString() doesn't expect a
> NULL argument, so passing one causes a segmentation fault.  This
> patch adds checks for NULL and raises errors via PLy_elog(), which
> prints details of the underlying Python exception.  The patch also
> adds regression tests for these checks.  All tests pass on my
> Solaris 9 box running HEAD and Python 2.4.1.
>
> In one place the patch doesn't call PLy_elog() because that could
> cause infinite recursion; see the comment I added.  I'm not sure
> how to test that particular case or whether it's even possible to
> get an error there: the value that the code should check is the
> Python exception type, so I wonder if a NULL value "shouldn't
> happen."  This patch converts NULL to "Unknown Exception" but I
> wonder if an Assert() would be appropriate.
>
> The patch is against HEAD but the same changes should be applied
> to earlier versions because they have the same problem.  The patch
> might not apply cleanly against earlier versions -- will the committer
> take care of little differences or should I submit different versions
> of the patch?

I am unclear about backpatching this.  We have to weigh the risks of
applying or not applying to 8.0.X.  Comments?

--
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  pgman@candle.pha.pa.us               |  (610) 359-1001
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