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Re: Plpython bug with int8 - Found, need advice

From: Bradley McLean <brad(at)bradm(dot)net>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Plpython bug with int8 - Found, need advice
Date: 2001-10-01 17:41:01
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
Replying to my own method.

In src/pl/plpython/plpython.c around line 1381, PLy_input_datum_func2
erroneously assigns PLyInt_FromString to handle int8 types.

Because PLyInt_FromString uses strtol at line 1461, it fails as
soon as you pass it a parameter exceed the bounds of an int4.

There are two problems to solve here:

1)  All of the conversion functions that return NULL ( line 1463 as
an example, page up and down from there) will cause the backend to terminate
abnormally.  I'm not sure if this is considered a correct behavior,
or if elog(ERROR, ...) is a better approach.  Comments?

2) I need an input conversion from string to int8, like perhaps
PLyLongLong_FromString() as an proposal.  src/backend/utils
/adt/int8.c has one, but it's not really well designed for access
from C.  Should I duplicate the functionality, figure out how to
wrap it for the call from plpython.c, or is there an existing
standard for factoring the body of the int8in function into a
widely available utility location.

Hope those questions are clear.  I'd like to get a patch in
before Beta.


* Bradley McLean (brad(at)bradm(dot)net) [010929 01:55]:
> Can someone else run this and confirm the results against the tip
> of the CVS repository?
> I'm trying to trace this bug (help welcome too).
> (it was hidden in a trigger and a pain to narrow to this point)
> -Brad
> -----
> drop function mul1(int4,int4);
> drop function mul2(int4,int4);
> drop function callmul1();
> drop function callmul2a();
> drop function callmul2b();
> create function mul1(int4,int4) returns int8 as 'select int8($1) * int8($2)' language 'sql';
> create function mul2(int4,int4) returns int8 as 'select int8($1) * 4294967296::int8 + int8($2)' language 'sql';
> create function callmul1() returns int8 as 'return plpy.execute("select mul1(6,7) as x")[0]["x"]' language 'plpython';
> create function callmul2a() returns int8 as 'select mul2(7,8)' language 'sql';
> create function callmul2b() returns int8 as 'return plpy.execute("select mul2(7,8) as x")[0]["x"]' language 'plpython';
> select mul1(3,4);
> select callmul1();
> select mul2(5,6);
> select callmul2a();
> select callmul2b();
> Results:
> ...
>  callmul1 
> ----------
>        42
> (1 row)
>     mul2     
> -------------
>  21474836486
> (1 row)
>   callmul2a  
> -------------
>  30064771080
> (1 row)
> psql:bug:14: pqReadData() -- backend closed the channel unexpectedly.
> 	This probably means the backend terminated abnormally
> 	before or while processing the request.
> psql:bug:14: connection to server was lost
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