Re: PL/Perl backed crashed during spi_exec_query - Mailing list pgsql-hackers

On Oct 31, 2009, at 7:30 PM, Tom Lane wrote:

> Alexey Klyukin <alexk@commandprompt.com> writes:
>> One of our customers is running 8.2.14 and use a couple of pl/perl  
>> and
>> pl/perlu functions written by CMD. Everything worked normally until
>> they tried to call one particular pl/perl function from pl/perl via
>> spi. It appears that a die call inside the callee just crashes the
>> backend.
>
> I think the critical point is actually that you're calling plperl from
> plperlu, and we're being careless about restoring the former  
> interpreter
> selection on error exit.  The attached patch moves the responsibility
> for that into plperl_call_handler, which already has a suitable
> PG_TRY block.

The patch solves the problem, thank you!

>
>             regards, tom lane
>
> Index: plperl.c
> ===================================================================
> RCS file: /cvsroot/pgsql/src/pl/plperl/plperl.c,v
> retrieving revision 1.152
> diff -c -r1.152 plperl.c
> *** plperl.c    28 Sep 2009 17:31:12 -0000    1.152
> --- plperl.c    31 Oct 2009 17:27:14 -0000
> ***************
> *** 380,390 ****
>      }
>  }
>
> !
>  static void
>  restore_context(bool old_context)
>  {
> !     if (trusted_context != old_context)
>      {
>          if (old_context)
>              PERL_SET_CONTEXT(plperl_trusted_interp);
> --- 380,392 ----
>      }
>  }
>
> ! /*
> !  * Restore previous interpreter selection, if two are active
> !  */
>  static void
>  restore_context(bool old_context)
>  {
> !     if (interp_state == INTERP_BOTH && trusted_context != old_context)
>      {
>          if (old_context)
>              PERL_SET_CONTEXT(plperl_trusted_interp);
> ***************
> *** 870,878 ****
>  plperl_call_handler(PG_FUNCTION_ARGS)
>  {
>      Datum        retval;
> !     plperl_call_data *save_call_data;
>
> -     save_call_data = current_call_data;
>      PG_TRY();
>      {
>          if (CALLED_AS_TRIGGER(fcinfo))
> --- 872,880 ----
>  plperl_call_handler(PG_FUNCTION_ARGS)
>  {
>      Datum        retval;
> !     plperl_call_data *save_call_data = current_call_data;
> !     bool        oldcontext = trusted_context;
>
>      PG_TRY();
>      {
>          if (CALLED_AS_TRIGGER(fcinfo))
> ***************
> *** 883,893 ****
> --- 885,897 ----
>      PG_CATCH();
>      {
>          current_call_data = save_call_data;
> +         restore_context(oldcontext);
>          PG_RE_THROW();
>      }
>      PG_END_TRY();
>
>      current_call_data = save_call_data;
> +     restore_context(oldcontext);
>      return retval;
>  }
>
> ***************
> *** 1226,1232 ****
>      Datum        retval;
>      ReturnSetInfo *rsi;
>      SV           *array_ret = NULL;
> -     bool        oldcontext = trusted_context;
>      ErrorContextCallback pl_error_context;
>
>      /*
> --- 1230,1235 ----
> ***************
> *** 1376,1384 ****
>      if (array_ret == NULL)
>          SvREFCNT_dec(perlret);
>
> -     current_call_data = NULL;
> -     restore_context(oldcontext);
> -
>      return retval;
>  }
>
> --- 1379,1384 ----
> ***************
> *** 1391,1397 ****
>      Datum        retval;
>      SV           *svTD;
>      HV           *hvTD;
> -     bool        oldcontext = trusted_context;
>      ErrorContextCallback pl_error_context;
>
>      /*
> --- 1391,1396 ----
> ***************
> *** 1491,1498 ****
>      if (perlret)
>          SvREFCNT_dec(perlret);
>
> -     current_call_data = NULL;
> -     restore_context(oldcontext);
>      return retval;
>  }
>
> --- 1490,1495 ----