Horton

Re: Fix for recursive plpython triggers

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andreas Karlsson <andreas@proxel.se>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2024-05-08T15:51:17Z
Lists: pgsql-hackers

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Andreas Karlsson <andreas@proxel.se> writes:
> I found this issue while reading the code, so am very unclear if there 
> is any sane code which could trigger it.

> In the example below the recursive call to f('int') changes the return 
> type of the f('text') call causing it to fail.

> # CREATE OR REPLACE FUNCTION f(t text) RETURNS record LANGUAGE 
> plpython3u AS $$
> if t == "text":
>      plpy.execute("SELECT * FROM f('int') AS (a int)");
>      return { "a": "x" }
> elif t == "int":
>      return { "a": 1 }
> $$;
> CREATE FUNCTION

> # SELECT * FROM f('text') AS (a text);
> ERROR:  invalid input syntax for type integer: "x"
> CONTEXT:  while creating return value
> PL/Python function "f"

Oh, nice one.  I think we can fix this trivially though: the problem
is that RECORD return-type setup was stuck into PLy_function_build_args,
where it has no particular business being in the first place, rather
than being done at the point of use.  We can just move the code.

			regards, tom lane

Commits

  1. Fix recursive RECORD-returning plpython functions.

  2. Don't corrupt plpython's "TD" dictionary in a recursive trigger call.