Re: can't load plpython - Mailing list pgsql-hackers

Alvaro Herrera escreveu:
> Euler Taveira de Oliveira wrote:
>> Tom Lane escreveu:
>>> Alvaro Herrera <alvherre@commandprompt.com> writes:
>>>> ... However, on HEAD this is crashing for me, and it's right when plpython
>>>> loads.  Backtrace below.
>>> Does plpython pass its regression tests for you (I'd suppose not)?
>>>
>>> For me on Fedora 10 x86_64, CVS HEAD plus python 2.5.2 passes regression
>>> but the given example still dumps core.  postmaster log says
>>>
>>> postgres: tgl regression [local] SELECT: Objects/stringobject.c:107: PyString_FromString: Assertion `str != ((void
*)0)'failed. 
>>> LOG:  server process (PID 4714) was terminated by signal 6: Aborted
>>> LOG:  terminating any other active server processes
>>>
>> PyString_FromString() [1] fails to return something useful, i.e, null pointer
>> when  its argument is null.  The trivial fix (that is attached) is to ensure
>> that we don't pass a null pointer as the second argument of
>> PyDict_SetItemString(). Of course, it's a Python bug and I filled it [3].
>
> I'm not sure I'm reading this right, but isn't this preventing a
> plpytHon function to work if parameters don't have names assigned?
No. See the proc->argnames test before PyDict_SetItemString(). The other test
is just tightening the check.

Indeed, the PyDict_*ItemString() functions suffer from the same disease. :( I
reported upstream too.

Attached is another patch that add another test before PyDict_DelItemString();
it's safe because if we don't have a key we don't know what to remove.

Here is my test case (I'm not a python programmer, sorry!).

euler@harman $ cat /tmp/{f,g}.sql
create or replace function unaccent(text) returns text language plpythonu as $$
import unicodedata
s = unicodedata.normalize("NFKD", args[0])
s = ''.join(c for c in s if ord(c) < 127)
return s
$$ ;
drop function add(int, int);
drop function add2(int, int);

create or replace function add(a int, b int) returns int language plpythonu as $$
return a + b
$$ ;

create or replace function add2(int, int) returns int language plpythonu as $$
return args[0] + args[1]
$$ ;

euler@harman $ ./install/bin/psql
psql (8.4devel)
Type "help" for help.

euler=# select unaccent('até');
NOTA:  PL/Python: args[0]: (null)
ERRO:  PL/Python: PL/Python function "unaccent" failed
DETALHE:  <type 'exceptions.TypeError'>: normalize() argument 2 must be
unicode, not str
euler=# select add(1,2);
NOTA:  PL/Python: args[0]: a
NOTA:  PL/Python: args[1]: b
NOTA:  PL/Python: args[0]: a
NOTA:  PL/Python: args[1]: b
 add
-----
   3
(1 registro)

euler=# select add2(1,2);
NOTA:  PL/Python: args[0]: (null)
NOTA:  PL/Python: args[1]: (null)
NOTA:  PL/Python: args[0]: (null)
NOTA:  PL/Python: args[1]: (null)
 add2
------
    3
(1 registro)


--
  Euler Taveira de Oliveira
  http://www.timbira.com/
Index: plpython.c
===================================================================
RCS file: /a/pgsql/dev/anoncvs/pgsql/src/pl/plpython/plpython.c,v
retrieving revision 1.118
diff -c -r1.118 plpython.c
*** plpython.c    15 Jan 2009 13:49:56 -0000    1.118
--- plpython.c    31 Mar 2009 18:50:54 -0000
***************
*** 1053,1059 ****
              }

              if (PyList_SetItem(args, i, arg) == -1 ||
!                 (proc->argnames &&
                   PyDict_SetItemString(proc->globals, proc->argnames[i], arg) == -1))
                  PLy_elog(ERROR, "PyDict_SetItemString() failed for PL/Python function \"%s\" while setting up
arguments",proc->proname); 
              arg = NULL;
--- 1053,1059 ----
              }

              if (PyList_SetItem(args, i, arg) == -1 ||
!                 (proc->argnames && proc->argnames[i] != NULL &&
                   PyDict_SetItemString(proc->globals, proc->argnames[i], arg) == -1))
                  PLy_elog(ERROR, "PyDict_SetItemString() failed for PL/Python function \"%s\" while setting up
arguments",proc->proname); 
              arg = NULL;
***************
*** 1081,1087 ****
          return;

      for (i = 0; i < proc->nargs; i++)
!         PyDict_DelItemString(proc->globals, proc->argnames[i]);
  }


--- 1081,1088 ----
          return;

      for (i = 0; i < proc->nargs; i++)
!         if (proc->argnames[i] != NULL)
!             PyDict_DelItemString(proc->globals, proc->argnames[i]);
  }