Re: [HACKERS] pl/perl extension fails on Windows

Ashutosh Sharma <ashu.coek88@gmail.com> writes:
> Thanks for the patch. I am seeing some compilation errors on Windows
> with the patch. Below are the errors observed,
> ...
> I did spent some time to find reason for these compilation errors and
> could eventually find that some of the Windows specific functions
> inside plperl module are calling Perl APIs without fetching the perl
> interpreter's context using dTHX.

Ah, thanks.  I just stuck that in where compiler errors were telling
me to, so I didn't realize there were Windows-specific functions to
worry about.

> Moreover, I have also tested this patch along with the patch to import
> switches used by perl into plperl and together it fixes the server
> crash issue. Also, now, the interpreter size in both perl and plperl
> module are the same thereby generating the same key on both plperl and
> perl module. Thanks.

Excellent.  So this looks like the avenue to pursue.

As far as the question of which symbols to import goes: on my own
machines I'm seeing a lot of things like

$ perl -MConfig -e 'print $Config{ccflags}'
-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64

$ perl -MConfig -e 'print $Config{ccflags}'-Ae -D_HPUX_SOURCE -Wl,+vnocompatwarnings -DDEBUGGING -I/usr/local/include
-D_LARGEFILE_SOURCE-D_FILE_OFFSET_BITS=64  

I'm really quite afraid to import symbols like _LARGEFILE_SOURCE and
_FILE_OFFSET_BITS into plperl; those *will* break things if they
are different from what core Postgres is built with.  Moreover,
I came across a relevant data structure in perl.h:

/* These are all the compile time options that affect binary compatibility.  Other compile time options that are binary
compatibleare in perl.c  Both are combined for the output of perl -V  However, this string will be embedded in any
sharedperl library, which will  allow us add a comparison check in perlmain.c in the near future.  */ 
#ifdef DOINIT
EXTCONST char PL_bincompat_options[] =
#  ifdef DEBUG_LEAKING_SCALARS             " DEBUG_LEAKING_SCALARS"
#  endif
#  ifdef DEBUG_LEAKING_SCALARS_FORK_DUMP             " DEBUG_LEAKING_SCALARS_FORK_DUMP"
#  endif
#  ifdef FAKE_THREADS             " FAKE_THREADS"
#  endif
#  ifdef MULTIPLICITY             " MULTIPLICITY"
#  endif
... lots more ...

Assuming that the Perl crew know what they're doing and this list is
complete, I notice that not one of the symbols they show as relevant
starts with an underscore.  So I'm thinking that my previous semi-
joking idea of absorbing only -D switches for names that *don't*
start with an underscore was actually a good solution.  If that
turns out to not be enough of a filter, we could consider looking
into perl.h to extract the set of symbols tested in building
PL_bincompat_options and then intersecting that with what we get
from Perl's ccflags.  But that would be a lot more complex, so
I'd rather go with the simpler filter rule for now.

(BTW, you never did tell us exactly what defines you're getting
out of Perl's flags on the problem installation.)
        regards, tom lane