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From: Andrew Dunstan <[email protected]>
To: Michael Fuhr <[email protected]>
Cc: [email protected]
Subject: Re: PL/Perl list value return causes segfault
Date: Tue, 12 Jul 2005 14:59:37 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>



Michael Fuhr wrote:

>In the latest HEAD, a PL/Perl function that returns a list value
>instead of a reference causes a segmentation fault:
>
>CREATE FUNCTION foo() RETURNS integer[] AS $$
>return (1, 2, 3, 4);
>$$ LANGUAGE plperl;
>
>SELECT foo();
>server closed the connection unexpectedly
>
>Here's the stack trace:
>
>#0  0xfed45bcc in plperl_call_handler (fcinfo=0xffbfe230) at plperl.c:1031
>#1  0x0010e7d4 in ExecMakeFunctionResult (fcache=0x44af00, econtext=0x44ae58, 
>    isNull=0x44b470 "\177~\177\177\177\177\177\177", isDone=0x44b4d8) at execQual.c:1031
>#2  0x001122b0 in ExecProject (projInfo=0x44af00, isDone=0x44ae58) at execQual.c:3607
>  
>


Patch below fixes the SEGV, and you will see instead:

andrew=# select foo();
ERROR:  array value must start with "{" or dimension information

which might not immediately point you to the source of the error :-( , 
but is certainly better than a SEGV.

Note that all plperl functions are called in scalar context, and it is 
always wrong to return a list (as opposed to a listref). In fact, the 
value received might surprise you even if it worked (it would be the 
value of the last member of the list).

cheers

andrew


Index: plperl.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/pl/plperl/plperl.c,v
retrieving revision 1.85
diff -c -r1.85 plperl.c
*** plperl.c    12 Jul 2005 01:16:21 -0000      1.85
--- plperl.c    12 Jul 2005 18:52:54 -0000
***************
*** 1021,1027 ****
          char *val;
  
 
!         if (prodesc->fn_retisarray && SvTYPE(SvRV(perlret)) == SVt_PVAV)
          {
              array_ret = plperl_convert_to_pg_array(perlret);
              SvREFCNT_dec(perlret);
--- 1021,1028 ----
          char *val;
  
 
!         if (prodesc->fn_retisarray && SvROK(perlret) &&
!                       SvTYPE(SvRV(perlret)) == SVt_PVAV)
          {
              array_ret = plperl_convert_to_pg_array(perlret);
              SvREFCNT_dec(perlret);

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