/**********************************************************************
 * plperl.c - perl as a procedural language for PostgreSQL
 *
 * IDENTIFICATION
 *
 *	  This software is copyrighted by Mark Hollomon
 *	 but is shameless cribbed from pltcl.c by Jan Weick.
 *
 *	  The author hereby grants permission  to  use,  copy,	modify,
 *	  distribute,  and	license this software and its documentation
 *	  for any purpose, provided that existing copyright notices are
 *	  retained	in	all  copies  and  that	this notice is included
 *	  verbatim in any distributions. No written agreement, license,
 *	  or  royalty  fee	is required for any of the authorized uses.
 *	  Modifications to this software may be  copyrighted  by  their
 *	  author  and  need  not  follow  the licensing terms described
 *	  here, provided that the new terms are  clearly  indicated  on
 *	  the first page of each file where they apply.
 *
 *	  IN NO EVENT SHALL THE AUTHOR OR DISTRIBUTORS BE LIABLE TO ANY
 *	  PARTY  FOR  DIRECT,	INDIRECT,	SPECIAL,   INCIDENTAL,	 OR
 *	  CONSEQUENTIAL   DAMAGES  ARISING	OUT  OF  THE  USE  OF  THIS
 *	  SOFTWARE, ITS DOCUMENTATION, OR ANY DERIVATIVES THEREOF, EVEN
 *	  IF  THE  AUTHOR  HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH
 *	  DAMAGE.
 *
 *	  THE  AUTHOR  AND	DISTRIBUTORS  SPECIFICALLY	 DISCLAIM	ANY
 *	  WARRANTIES,  INCLUDING,  BUT	NOT  LIMITED  TO,  THE	IMPLIED
 *	  WARRANTIES  OF  MERCHANTABILITY,	FITNESS  FOR  A  PARTICULAR
 *	  PURPOSE,	AND NON-INFRINGEMENT.  THIS SOFTWARE IS PROVIDED ON
 *	  AN "AS IS" BASIS, AND THE AUTHOR	AND  DISTRIBUTORS  HAVE  NO
 *	  OBLIGATION   TO	PROVIDE   MAINTENANCE,	 SUPPORT,  UPDATES,
 *	  ENHANCEMENTS, OR MODIFICATIONS.
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/pl/plperl/plperl.c,v 1.40.2.5 2010/05/17 20:46:03 adunstan Exp $
 *
 **********************************************************************/

#include "postgres.h"

/* system stuff */
#include <unistd.h>
#include <fcntl.h>
#include <setjmp.h>

/* postgreSQL stuff */
#include "executor/spi.h"
#include "commands/trigger.h"
#include "fmgr.h"
#include "mb/pg_wchar.h"
#include "access/heapam.h"
#include "tcop/tcopprot.h"
#include "utils/syscache.h"
#include "catalog/pg_language.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "utils/hsearch.h"

/* perl stuff */
#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"
#include "ppport.h"

/* just in case these symbols aren't provided */
#ifndef pTHX_
#define pTHX_
#define pTHX void
#endif

/* defines PLPERL_SET_OPMASK */
#include "plperl_opmask.h"


/**********************************************************************
 * The information we cache about loaded procedures
 **********************************************************************/
typedef struct plperl_proc_desc
{
	char	   *proname;
	TransactionId fn_xmin;
	CommandId	fn_cmin;
	bool		lanpltrusted;
	FmgrInfo	result_in_func;
	Oid			result_in_elem;
	int			nargs;
	FmgrInfo	arg_out_func[FUNC_MAX_ARGS];
	Oid			arg_out_elem[FUNC_MAX_ARGS];
	int			arg_is_rel[FUNC_MAX_ARGS];
	SV		   *reference;
} plperl_proc_desc;

/**********************************************************************
 * Global data
 **********************************************************************/

typedef enum
{
	INTERP_NONE,
	INTERP_HELD,
	INTERP_TRUSTED,
	INTERP_UNTRUSTED,
	INTERP_BOTH
} InterpState;

static InterpState interp_state = INTERP_NONE;
static bool can_run_two = false;

static int	plperl_firstcall = 1;
static bool plperl_safe_init_done = false;
static PerlInterpreter *plperl_trusted_interp = NULL;
static PerlInterpreter *plperl_untrusted_interp = NULL;
static PerlInterpreter *plperl_held_interp = NULL;
static OP  *(*pp_require_orig) (pTHX) = NULL;
static OP  *pp_require_safe(pTHX);
static bool trusted_context;
static HTAB *plperl_proc_hash = NULL;
static char plperl_opmask[MAXO];
static void set_interp_require(void);

/**********************************************************************
 * Forward declarations
 **********************************************************************/
static void plperl_init_all(void);
static void plperl_init_interp(void);

Datum		plperl_call_handler(PG_FUNCTION_ARGS);
void		plperl_init(void);

static Datum plperl_func_handler(PG_FUNCTION_ARGS);

static plperl_proc_desc *compile_plperl_function(Oid fn_oid, bool is_trigger);

static SV  *plperl_build_tuple_argument(HeapTuple tuple, TupleDesc tupdesc);
static void plperl_init_shared_libs(pTHX);
static void plperl_safe_init(void);
static char *strip_trailing_ws(const char *msg);

/* hash table entry for proc desc  */

typedef struct plperl_proc_entry
{
	char		proc_name[NAMEDATALEN];
	plperl_proc_desc *proc_data;
} plperl_proc_entry;


/*
 * This routine is a crock, and so is everyplace that calls it.  The problem
 * is that the cached form of plperl functions/queries is allocated permanently
 * (mostly via malloc()) and never released until backend exit.  Subsidiary
 * data structures such as fmgr info records therefore must live forever
 * as well.  A better implementation would store all this stuff in a per-
 * function memory context that could be reclaimed at need.  In the meantime,
 * fmgr_info_cxt must be called specifying TopMemoryContext so that whatever
 * it might allocate, and whatever the eventual function might allocate using
 * fn_mcxt, will live forever too.
 */
static void
perm_fmgr_info(Oid functionId, FmgrInfo *finfo)
{
	fmgr_info_cxt(functionId, finfo, TopMemoryContext);
}

/**********************************************************************
 * plperl_init()			- Initialize everything that can be
 *							  safely initialized during postmaster
 *							  startup.
 *
 * DO NOT make this static --- it has to be callable by preload
 **********************************************************************/
void
plperl_init(void)
{
	HASHCTL		hash_ctl;

	/************************************************************
	 * Do initialization only once
	 ************************************************************/
	if (!plperl_firstcall)
		return;

	MemSet(&hash_ctl, 0, sizeof(hash_ctl));

	hash_ctl.keysize = NAMEDATALEN;
	hash_ctl.entrysize = sizeof(plperl_proc_entry);

	plperl_proc_hash = hash_create("PLPerl Procedures",
								   32,
								   &hash_ctl,
								   HASH_ELEM);

	/************************************************************
	 * Now recreate a new Perl interpreter
	 ************************************************************/
	PLPERL_SET_OPMASK(plperl_opmask);

	plperl_init_interp();

	plperl_firstcall = 0;
}

/**********************************************************************
 * plperl_init_all()		- Initialize all
 **********************************************************************/
static void
plperl_init_all(void)
{

	/************************************************************
	 * Execute postmaster-startup safe initialization
	 ************************************************************/
	if (plperl_firstcall)
		plperl_init();

	/************************************************************
	 * Any other initialization that must be done each time a new
	 * backend starts -- currently none
	 ************************************************************/

}

#define PLC_TRUSTED \
	"require strict; "

#define TEST_FOR_MULTI \
	"use Config; " \
	"$Config{usemultiplicity} eq 'define' or "	\
	"($Config{usethreads} eq 'define' " \
	" and $Config{useithreads} eq 'define')"


static void
set_interp_require(void)
{
	if (trusted_context)
	{
		PL_ppaddr[OP_REQUIRE] = pp_require_safe;
		PL_ppaddr[OP_DOFILE] = pp_require_safe;
	}
	else
	{
		PL_ppaddr[OP_REQUIRE] = pp_require_orig;
		PL_ppaddr[OP_DOFILE] = pp_require_orig;
	}
}

/********************************************************************
 *
 * We start out by creating a "held" interpreter that we can use in
 * trusted or untrusted mode (but not both) as the need arises. Later, we
 * assign that interpreter if it is available to either the trusted or
 * untrusted interpreter. If it has already been assigned, and we need to
 * create the other interpreter, we do that if we can, or error out.
 * We detect if it is safe to run two interpreters during the setup of the
 * dummy interpreter.
 */


static void
check_interp(bool trusted)
{
	if (interp_state == INTERP_HELD)
	{
		if (trusted)
		{
			plperl_trusted_interp = plperl_held_interp;
			interp_state = INTERP_TRUSTED;
		}
		else
		{
			plperl_untrusted_interp = plperl_held_interp;
			interp_state = INTERP_UNTRUSTED;
		}
		plperl_held_interp = NULL;
		trusted_context = trusted;
		set_interp_require();
	}
	else if (interp_state == INTERP_BOTH ||
			 (trusted && interp_state == INTERP_TRUSTED) ||
			 (!trusted && interp_state == INTERP_UNTRUSTED))
	{
		if (trusted_context != trusted)
		{
			if (trusted)
				PERL_SET_CONTEXT(plperl_trusted_interp);
			else
				PERL_SET_CONTEXT(plperl_untrusted_interp);
			trusted_context = trusted;
			set_interp_require();
		}
	}
	else if (can_run_two)
	{
		PERL_SET_CONTEXT(plperl_held_interp);
		plperl_init_interp();
		if (trusted)
			plperl_trusted_interp = plperl_held_interp;
		else
			plperl_untrusted_interp = plperl_held_interp;
		interp_state = INTERP_BOTH;
		plperl_held_interp = NULL;
		trusted_context = trusted;
		set_interp_require();
	}
	else
	{
		elog(ERROR,
			 "can not allocate second Perl interpreter on this platform");

	}

}


static void
restore_context(bool old_context)
{
	if (trusted_context != old_context)
	{
		if (old_context)
			PERL_SET_CONTEXT(plperl_trusted_interp);
		else
			PERL_SET_CONTEXT(plperl_untrusted_interp);

		trusted_context = old_context;
		set_interp_require();
	}
}

/**********************************************************************
 * plperl_init_interp() - Create the Perl interpreter
 **********************************************************************/
static void
plperl_init_interp(void)
{

	char	   *embedding[3] = {
		"", "-e",

		/*
		 * no commas between the next lines please. They are supposed to be
		 * one string
		 */
		"SPI::bootstrap();"
		"sub ::mkfunc {return eval(qq[ sub { $_[0] } ]); }"
	};

	/****
	 * The perl API docs state that PERL_SYS_INIT3 should be called before
	 * allocating interprters. Unfortunately, on some platforms this fails
	 * in the Perl_do_taint() routine, which is called when the platform is
	 * using the system's malloc() instead of perl's own. Other platforms,
	 * fail if PERL_SYS_INIT3 is not called. So we call it
	 * if it's available, unless perl is using the system malloc(), which is
	 * true when MYMALLOC is set.
	 */
#if defined(PERL_SYS_INIT3) && !defined(MYMALLOC)
	if (interp_state == INTERP_NONE)
	{
		int			nargs;
		char	   *dummy_perl_env[1];

		/* initialize this way to silence silly compiler warnings */
		nargs = 3;
		dummy_perl_env[0] = NULL;
		PERL_SYS_INIT3(&nargs, (char ***) &embedding, (char ***) &dummy_perl_env);
	}
#endif

	plperl_held_interp = perl_alloc();
	if (!plperl_held_interp)
		elog(ERROR, "could not allocate Perl interpreter");

	perl_construct(plperl_held_interp);

	/*
	 * Record the original function for the 'require' and 'dofile' opcodes.
	 * (They share the same implementation.) Ensure it's used for new
	 * interpreters.
	 */
	if (!pp_require_orig)
	{
		pp_require_orig = PL_ppaddr[OP_REQUIRE];
	}
	else
	{
		PL_ppaddr[OP_REQUIRE] = pp_require_orig;
		PL_ppaddr[OP_DOFILE] = pp_require_orig;
	}

	perl_parse(plperl_held_interp, plperl_init_shared_libs,
			   3, embedding, NULL);
	perl_run(plperl_held_interp);

	if (interp_state == INTERP_NONE)
	{
		SV		   *res;

		res = eval_pv(TEST_FOR_MULTI, TRUE);
		can_run_two = SvIV(res);
		interp_state = INTERP_HELD;
	}
}


/**********************************************************************
 * plperl_call_handler		- This is the only visible function
 *				  of the PL interpreter. The PostgreSQL
 *				  function manager and trigger manager
 *				  call this function for execution of
 *				  perl procedures.
 **********************************************************************/
PG_FUNCTION_INFO_V1(plperl_call_handler);

/* keep non-static */
Datum
plperl_call_handler(PG_FUNCTION_ARGS)
{
	Datum		retval;
	bool		oldcontext = trusted_context;
	sigjmp_buf	save_restart;

	/************************************************************
	 * Initialize interpreter
	 ************************************************************/
	plperl_init_all();

	/************************************************************
	 * Connect to SPI manager
	 ************************************************************/
	if (SPI_connect() != SPI_OK_CONNECT)
		elog(ERROR, "could not connect to SPI manager");

	/************************************************************
	 * Determine if called as function or trigger and
	 * call appropriate subhandler
	 ************************************************************/

	memcpy(&save_restart, &Warn_restart, sizeof(save_restart));
	if (sigsetjmp(Warn_restart, 1) != 0)
	{
		memcpy(&Warn_restart, &save_restart, sizeof(Warn_restart));
		restore_context(oldcontext);
		siglongjmp(Warn_restart, 1);
	}


	if (CALLED_AS_TRIGGER(fcinfo))
	{
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("cannot use perl in triggers yet")));

		/*
		 * retval = PointerGetDatum(plperl_trigger_handler(fcinfo));
		 */
		/* make the compiler happy */
		retval = (Datum) 0;
	}
	else
	{
		/* non-trigger functions are ok */
		retval = plperl_func_handler(fcinfo);
	}

	memcpy(&Warn_restart, &save_restart, sizeof(Warn_restart));
	restore_context(oldcontext);
	return retval;
}


/**********************************************************************
 * plperl_create_sub()		- calls the perl interpreter to
 *		create the anonymous subroutine whose text is in the SV.
 *		Returns the SV containing the RV to the closure.
 **********************************************************************/
static SV  *
plperl_create_sub(char *s, bool trusted)
{
	dSP;
	SV		   *subref;
	int			count;

	if (trusted && !plperl_safe_init_done)
	{
		plperl_safe_init();
		SPAGAIN;
	}

	ENTER;
	SAVETMPS;
	PUSHMARK(SP);
	XPUSHs(sv_2mortal(newSVpv(s, 0)));
	PUTBACK;

	/*
	 * G_KEEPERR seems to be needed here, else we don't recognize compile
	 * errors properly.  Perhaps it's because there's another level of eval
	 * inside mkfunc?
	 */
	count = perl_call_pv("::mkfunc",
						 G_SCALAR | G_EVAL | G_KEEPERR);
	SPAGAIN;

	if (count != 1)
	{
		PUTBACK;
		FREETMPS;
		LEAVE;
		elog(ERROR, "didn't get a return item from mkfunc");
	}

	if (SvTRUE(ERRSV))
	{
		POPs;
		PUTBACK;
		FREETMPS;
		LEAVE;
		elog(ERROR, "creation of function failed: %s", SvPV(ERRSV, PL_na));
	}

	/*
	 * need to make a deep copy of the return. it comes off the stack as a
	 * temporary.
	 */
	subref = newSVsv(POPs);

	if (!SvROK(subref))
	{
		PUTBACK;
		FREETMPS;
		LEAVE;

		/*
		 * subref is our responsibility because it is not mortal
		 */
		SvREFCNT_dec(subref);
		elog(ERROR, "didn't get a code ref");
	}

	PUTBACK;
	FREETMPS;
	LEAVE;

	return subref;
}

/*
 * Our safe implementation of the require opcode.
 * This is safe because it's completely unable to load any code.
 * If the requested file/module has already been loaded it'll return true.
 * If not, it'll die.
 * So now "use Foo;" will work iff Foo has already been loaded.
 */
static OP  *
pp_require_safe(pTHX)
{
	dVAR;
	dSP;
	SV		   *sv,
			  **svp;
	char	   *name;
	STRLEN		len;

	sv = POPs;
	name = SvPV(sv, len);
	if (!(name && len > 0 && *name))
		RETPUSHNO;

	svp = hv_fetch(GvHVn(PL_incgv), name, len, 0);
	if (svp && *svp != &PL_sv_undef)
		RETPUSHYES;

	DIE(aTHX_ "Unable to load %s into plperl", name);
}

static void
plperl_safe_init(void)
{
	HV		   *stash;
	SV		   *sv;
	char	   *key;
	I32			klen;

	/* use original require while we set up */
	PL_ppaddr[OP_REQUIRE] = pp_require_orig;
	PL_ppaddr[OP_DOFILE] = pp_require_orig;

	eval_pv(PLC_TRUSTED, FALSE);
	if (SvTRUE(ERRSV))
		ereport(ERROR,
				(errmsg("%s", strip_trailing_ws(SvPV_nolen(ERRSV))),
				 errcontext("while executing PLC_TRUSTED")));

	if (GetDatabaseEncoding() == PG_UTF8)
	{
		/*
		 * Force loading of utf8 module now to prevent errors that can arise
		 * from the regex code later trying to load utf8 modules. See
		 * http://rt.perl.org/rt3/Ticket/Display.html?id=47576
		 */
		eval_pv("my $a=chr(0x100); return $a =~ /\\xa9/i", FALSE);
		if (SvTRUE(ERRSV))
			ereport(ERROR,
					(errmsg("%s", strip_trailing_ws(SvPV_nolen(ERRSV))),
					 errcontext("while executing utf8fix")));

	}

	/*
	 * Lock down the interpreter
	 */

	/* switch to the safe require/dofile opcode for future code */
	PL_ppaddr[OP_REQUIRE] = pp_require_safe;
	PL_ppaddr[OP_DOFILE] = pp_require_safe;

	/* 
	 * prevent (any more) unsafe opcodes being compiled 
	 * PL_op_mask is per interpreter, so this only needs to be set once 
	 */
	PL_op_mask = plperl_opmask;
	/* delete the DynaLoader:: namespace so extensions can't be loaded */
	stash = gv_stashpv("DynaLoader", GV_ADDWARN);
	hv_iterinit(stash);
	while ((sv = hv_iternextsv(stash, &key, &klen)))
	{
		if (!isGV_with_GP(sv) || !GvCV(sv))
			continue;
		SvREFCNT_dec(GvCV(sv)); /* free the CV */
		GvCV(sv) = NULL;		/* prevent call via GV */
	}

	hv_clear(stash);
	/* invalidate assorted caches */
	++PL_sub_generation;
#ifdef PL_stashcache
	hv_clear(PL_stashcache);
#endif

	plperl_safe_init_done = true;
}


/**********************************************************************
 * plperl_init_shared_libs()		-
 *
 * We cannot use the DynaLoader directly to get at the Opcode
 * module. So, we link Opcode into ourselves
 * and do the initialization behind perl's back.
 *
 **********************************************************************/

EXTERN_C void boot_DynaLoader(pTHX_ CV *cv);
EXTERN_C void boot_SPI(pTHX_ CV *cv);

static void
plperl_init_shared_libs(pTHX)
{
	char	   *file = __FILE__;

	newXS("DynaLoader::boot_DynaLoader", boot_DynaLoader, file);
	newXS("SPI::bootstrap", boot_SPI, file);
}

/**********************************************************************
 * plperl_call_perl_func()		- calls a perl function through the RV
 *			stored in the prodesc structure. massages the input parms properly
 **********************************************************************/
static SV  *
plperl_call_perl_func(plperl_proc_desc *desc, FunctionCallInfo fcinfo)
{
	dSP;
	SV		   *retval;
	int			i;
	int			count;

	ENTER;
	SAVETMPS;

	PUSHMARK(SP);
	for (i = 0; i < desc->nargs; i++)
	{
		if (desc->arg_is_rel[i])
		{
			TupleTableSlot *slot = (TupleTableSlot *) fcinfo->arg[i];
			SV		   *hashref;

			Assert(slot != NULL && !fcinfo->argnull[i]);

			/*
			 * plperl_build_tuple_argument better return a mortal SV.
			 */
			hashref = plperl_build_tuple_argument(slot->val,
												  slot->ttc_tupleDescriptor);
			XPUSHs(hashref);
		}
		else
		{
			if (fcinfo->argnull[i])
				XPUSHs(&PL_sv_undef);
			else
			{
				char	   *tmp;

				tmp = DatumGetCString(FunctionCall3(&(desc->arg_out_func[i]),
													fcinfo->arg[i],
									 ObjectIdGetDatum(desc->arg_out_elem[i]),
													Int32GetDatum(-1)));
				XPUSHs(sv_2mortal(newSVpv(tmp, 0)));
				pfree(tmp);
			}
		}
	}
	PUTBACK;

	/* Do NOT use G_KEEPERR here */
	count = perl_call_sv(desc->reference, G_SCALAR | G_EVAL);

	SPAGAIN;

	if (count != 1)
	{
		PUTBACK;
		FREETMPS;
		LEAVE;
		elog(ERROR, "didn't get a return item from function");
	}

	if (SvTRUE(ERRSV))
	{
		POPs;
		PUTBACK;
		FREETMPS;
		LEAVE;
		elog(ERROR, "error from function: %s", SvPV(ERRSV, PL_na));
	}

	retval = newSVsv(POPs);

	PUTBACK;
	FREETMPS;
	LEAVE;

	return retval;
}


/**********************************************************************
 * plperl_func_handler()		- Handler for regular function calls
 **********************************************************************/
static Datum
plperl_func_handler(PG_FUNCTION_ARGS)
{
	plperl_proc_desc *prodesc;
	SV		   *perlret;
	Datum		retval;

	/* Find or compile the function */
	prodesc = compile_plperl_function(fcinfo->flinfo->fn_oid, false);

	check_interp(prodesc->lanpltrusted);

	/************************************************************
	 * Call the Perl function
	 ************************************************************/
	perlret = plperl_call_perl_func(prodesc, fcinfo);

	/************************************************************
	 * Disconnect from SPI manager and then create the return
	 * values datum (if the input function does a palloc for it
	 * this must not be allocated in the SPI memory context
	 * because SPI_finish would free it).
	 ************************************************************/
	if (SPI_finish() != SPI_OK_FINISH)
		elog(ERROR, "SPI_finish() failed");

	if (!(perlret && SvOK(perlret)))
	{
		/* return NULL if Perl code returned undef */
		retval = (Datum) 0;
		fcinfo->isnull = true;
	}
	else
	{
		retval = FunctionCall3(&prodesc->result_in_func,
							   PointerGetDatum(SvPV(perlret, PL_na)),
							   ObjectIdGetDatum(prodesc->result_in_elem),
							   Int32GetDatum(-1));
	}

	SvREFCNT_dec(perlret);

	return retval;
}


/**********************************************************************
 * compile_plperl_function	- compile (or hopefully just look up) function
 **********************************************************************/
static plperl_proc_desc *
compile_plperl_function(Oid fn_oid, bool is_trigger)
{
	HeapTuple	procTup;
	Form_pg_proc procStruct;
	char		internal_proname[64];
	int			proname_len;
	plperl_proc_desc *prodesc = NULL;
	int			i;
	plperl_proc_entry *hash_entry;
	bool		found;
	bool		oldcontext = trusted_context;

	/* We'll need the pg_proc tuple in any case... */
	procTup = SearchSysCache(PROCOID,
							 ObjectIdGetDatum(fn_oid),
							 0, 0, 0);
	if (!HeapTupleIsValid(procTup))
		elog(ERROR, "cache lookup failed for function %u", fn_oid);
	procStruct = (Form_pg_proc) GETSTRUCT(procTup);

	/************************************************************
	 * Build our internal proc name from the functions Oid
	 ************************************************************/
	if (!is_trigger)
		sprintf(internal_proname, "__PLPerl_proc_%u", fn_oid);
	else
		sprintf(internal_proname, "__PLPerl_proc_%u_trigger", fn_oid);
	proname_len = strlen(internal_proname);

	/************************************************************
	 * Lookup the internal proc name in the hashtable
	 ************************************************************/
	hash_entry = hash_search(plperl_proc_hash, internal_proname,
							 HASH_FIND, NULL);

	if (hash_entry)
	{
		bool		uptodate;

		prodesc = hash_entry->proc_data;

		/************************************************************
		 * If it's present, must check whether it's still up to date.
		 * This is needed because CREATE OR REPLACE FUNCTION can modify the
		 * function's pg_proc entry without changing its OID.
		 ************************************************************/
		uptodate = (prodesc->fn_xmin == HeapTupleHeaderGetXmin(procTup->t_data) &&
				prodesc->fn_cmin == HeapTupleHeaderGetCmin(procTup->t_data));

		if (!uptodate)
		{
			hash_search(plperl_proc_hash, internal_proname,
						HASH_REMOVE, NULL);
			if (prodesc->reference)
			{
				check_interp(prodesc->lanpltrusted);
				SvREFCNT_dec(prodesc->reference);
				restore_context(oldcontext);
			}
			free(prodesc->proname);
			free(prodesc);
			prodesc = NULL;
		}
	}

	/************************************************************
	 * If we haven't found it in the hashtable, we analyze
	 * the functions arguments and returntype and store
	 * the in-/out-functions in the prodesc block and create
	 * a new hashtable entry for it.
	 *
	 * Then we load the procedure into the Perl interpreter.
	 ************************************************************/
	if (prodesc == NULL)
	{
		HeapTuple	langTup;
		HeapTuple	typeTup;
		Form_pg_language langStruct;
		Form_pg_type typeStruct;
		char	   *proc_source;

		/************************************************************
		 * Allocate a new procedure description block
		 ************************************************************/
		prodesc = (plperl_proc_desc *) malloc(sizeof(plperl_proc_desc));
		if (prodesc == NULL)
			ereport(ERROR,
					(errcode(ERRCODE_OUT_OF_MEMORY),
					 errmsg("out of memory")));
		MemSet(prodesc, 0, sizeof(plperl_proc_desc));
		prodesc->proname = strdup(internal_proname);
		prodesc->fn_xmin = HeapTupleHeaderGetXmin(procTup->t_data);
		prodesc->fn_cmin = HeapTupleHeaderGetCmin(procTup->t_data);

		/************************************************************
		 * Lookup the pg_language tuple by Oid
		 ************************************************************/
		langTup = SearchSysCache(LANGOID,
								 ObjectIdGetDatum(procStruct->prolang),
								 0, 0, 0);
		if (!HeapTupleIsValid(langTup))
		{
			free(prodesc->proname);
			free(prodesc);
			elog(ERROR, "cache lookup failed for language %u",
				 procStruct->prolang);
		}
		langStruct = (Form_pg_language) GETSTRUCT(langTup);
		prodesc->lanpltrusted = langStruct->lanpltrusted;
		ReleaseSysCache(langTup);

		/************************************************************
		 * Get the required information for input conversion of the
		 * return value.
		 ************************************************************/
		if (!is_trigger)
		{
			typeTup = SearchSysCache(TYPEOID,
									 ObjectIdGetDatum(procStruct->prorettype),
									 0, 0, 0);
			if (!HeapTupleIsValid(typeTup))
			{
				free(prodesc->proname);
				free(prodesc);
				elog(ERROR, "cache lookup failed for type %u",
					 procStruct->prorettype);
			}
			typeStruct = (Form_pg_type) GETSTRUCT(typeTup);

			/* Disallow pseudotype result, except VOID */
			if (typeStruct->typtype == 'p')
			{
				if (procStruct->prorettype == VOIDOID)
					 /* okay */ ;
				else if (procStruct->prorettype == TRIGGEROID)
				{
					free(prodesc->proname);
					free(prodesc);
					ereport(ERROR,
							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
							 errmsg("trigger functions may only be called as triggers")));
				}
				else
				{
					free(prodesc->proname);
					free(prodesc);
					ereport(ERROR,
							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
							 errmsg("plperl functions cannot return type %s",
									format_type_be(procStruct->prorettype))));
				}
			}

			if (typeStruct->typrelid != InvalidOid)
			{
				free(prodesc->proname);
				free(prodesc);
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					   errmsg("plperl functions cannot return tuples yet")));
			}

			if (procStruct->proretset)
			{
				free(prodesc->proname);
				free(prodesc);
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("plperl functions cannot return sets yet")));
			}

			perm_fmgr_info(typeStruct->typinput, &(prodesc->result_in_func));
			prodesc->result_in_elem = typeStruct->typelem;


			ReleaseSysCache(typeTup);
		}

		/************************************************************
		 * Get the required information for output conversion
		 * of all procedure arguments
		 ************************************************************/
		if (!is_trigger)
		{
			prodesc->nargs = procStruct->pronargs;
			for (i = 0; i < prodesc->nargs; i++)
			{
				typeTup = SearchSysCache(TYPEOID,
								ObjectIdGetDatum(procStruct->proargtypes[i]),
										 0, 0, 0);
				if (!HeapTupleIsValid(typeTup))
				{
					free(prodesc->proname);
					free(prodesc);
					elog(ERROR, "cache lookup failed for type %u",
						 procStruct->proargtypes[i]);
				}
				typeStruct = (Form_pg_type) GETSTRUCT(typeTup);

				/* Disallow pseudotype argument */
				if (typeStruct->typtype == 'p')
				{
					free(prodesc->proname);
					free(prodesc);
					ereport(ERROR,
							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
							 errmsg("plperl functions cannot take type %s",
							   format_type_be(procStruct->proargtypes[i]))));
				}

				if (typeStruct->typrelid != InvalidOid)
					prodesc->arg_is_rel[i] = 1;
				else
					prodesc->arg_is_rel[i] = 0;

				perm_fmgr_info(typeStruct->typoutput, &(prodesc->arg_out_func[i]));
				prodesc->arg_out_elem[i] = typeStruct->typelem;
				ReleaseSysCache(typeTup);
			}
		}

		/************************************************************
		 * create the text of the anonymous subroutine.
		 * we do not use a named subroutine so that we can call directly
		 * through the reference.
		 *
		 ************************************************************/
		proc_source = DatumGetCString(DirectFunctionCall1(textout,
									  PointerGetDatum(&procStruct->prosrc)));

		/************************************************************
		 * Create the procedure in the interpreter
		 ************************************************************/

		check_interp(prodesc->lanpltrusted);

		prodesc->reference =
			plperl_create_sub(proc_source, prodesc->lanpltrusted);

		restore_context(oldcontext);

		pfree(proc_source);
		if (!prodesc->reference)
		{
			free(prodesc->proname);
			free(prodesc);
			elog(ERROR, "could not create internal procedure \"%s\"",
				 internal_proname);
		}

		/************************************************************
		 * Add the proc description block to the hashtable
		 ************************************************************/
		hash_entry = hash_search(plperl_proc_hash, internal_proname,
								 HASH_ENTER, &found);
		hash_entry->proc_data = prodesc;
	}

	ReleaseSysCache(procTup);

	return prodesc;
}


/**********************************************************************
 * plperl_build_tuple_argument() - Build a ref to a hash
 *				  from all attributes of a given tuple
 **********************************************************************/
static SV  *
plperl_build_tuple_argument(HeapTuple tuple, TupleDesc tupdesc)
{
	HV		   *hv;
	int			i;

	hv = newHV();

	for (i = 0; i < tupdesc->natts; i++)
	{
		Datum		attr;
		bool		isnull;
		char	   *attname;
		char	   *outputstr;
		Oid			typoutput;
		Oid			typioparam;
		bool		typisvarlena;
		int			namelen;

		if (tupdesc->attrs[i]->attisdropped)
			continue;

		attname = NameStr(tupdesc->attrs[i]->attname);
		namelen = strlen(attname);
		attr = heap_getattr(tuple, i + 1, tupdesc, &isnull);

		if (isnull)
		{
			/* Store (attname => undef) and move on. */
			hv_store(hv, attname, namelen, newSV(0), 0);
			continue;
		}

		/* XXX should have a way to cache these lookups */

		getTypeOutputInfo(tupdesc->attrs[i]->atttypid,
						  &typoutput, &typioparam, &typisvarlena);

		outputstr = DatumGetCString(OidFunctionCall3(typoutput,
													 attr,
												ObjectIdGetDatum(typioparam),
							   Int32GetDatum(tupdesc->attrs[i]->atttypmod)));

		hv_store(hv, attname, namelen, newSVpv(outputstr, 0), 0);
	}

	return newRV_noinc((SV *) hv);
}

/*
 * Perl likes to put a newline after its error messages; clean up such
 */
static char *
strip_trailing_ws(const char *msg)
{
	char	   *res = pstrdup(msg);
	int			len = strlen(res);

	while (len > 0 && isspace((unsigned char) res[len - 1]))
		res[--len] = '\0';
	return res;
}