Re: Custom variable class segmentation fault

Michael Fuhr wrote:
> The latest HEAD is segfaulting on startup if I have the following
> lines in postgresql.conf:
>
> custom_variable_classes = 'plperl'
> plperl.use_strict = on
>
> If I comment out the second line then the server starts successfully.
> Platform is Solaris 9/sparc.
>
> (gdb) bt
> #0  0xff0340a0 in strcmp () from /usr/lib/libc.so.1
> #1  0x00257504 in verify_config_option (name=0x0, value=0x397258 "on", context=PGC_POSTMASTER, source=PGC_S_FILE,
isNewEqual=0xffbff2cb"\001",  
>     isContextOK=0xffbff2ca "\001\001") at guc.c:5513
> #2  0x0025d3b4 in ProcessConfigFile (context=PGC_POSTMASTER) at guc-file.l:152
> #3  0x0025d80c in SelectConfigFiles (userDoption=0x1 <Address 0x1 out of bounds>, progname=0x390610 "postgres") at
guc.c:2867
> #4  0x0019a450 in PostmasterMain (argc=5, argv=0x391240) at postmaster.c:602
> #5  0x001518c8 in main (argc=5, argv=0x391240) at main.c:187

Thanks for the report.  This attached, applied patch fixes it.  The
problem was that custom variables have _no_ default value for strings on
startup, and the checking code was being too agressive.

--
  Bruce Momjian   bruce@momjian.us
  EnterpriseDB    http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +
Index: src/backend/utils/misc/guc.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v
retrieving revision 1.339
diff -c -c -r1.339 guc.c
*** src/backend/utils/misc/guc.c    13 Aug 2006 02:22:24 -0000    1.339
--- src/backend/utils/misc/guc.c    13 Aug 2006 15:34:13 -0000
***************
*** 5512,5518 ****
          {
              struct config_string *conf = (struct config_string *) record;

!             return strcmp(*conf->variable, newvalue) == 0;
          }
      }

--- 5512,5521 ----
          {
              struct config_string *conf = (struct config_string *) record;

!             if (!*conf->variable)    /* custom variable with no value yet */
!                 return false;
!             else
!                 return strcmp(*conf->variable, newvalue) == 0;
          }
      }