pl_comp.c

PostgreSQL7.4.6 for Linux

/**********************************************************************
 * pl_comp.c		- Compiler part of the PL/pgSQL
 *			  procedural language
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/pl/plpgsql/src/pl_comp.c,v 1.69 2003/09/30 00:59:51 tgl Exp $
 *
 *	  This software is copyrighted by Jan Wieck - Hamburg.
 *
 *	  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.
 *
 **********************************************************************/

#include "plpgsql.h"

#include <ctype.h>
#include <setjmp.h>

#include "pl.tab.h"

#include "access/heapam.h"
#include "catalog/catname.h"
#include "catalog/namespace.h"
#include "catalog/pg_attribute.h"
#include "catalog/pg_attrdef.h"
#include "catalog/pg_class.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
#include "parser/gramparse.h"
#include "parser/parse_type.h"
#include "tcop/tcopprot.h"
#include "utils/builtins.h"
#include "utils/syscache.h"


/* ----------
 * Variables in the parser that shouldn't go into plpgsql.h
 * ----------
 */
extern PLPGSQL_YYSTYPE plpgsql_yylval;

/* ----------
 * Our own local and global variables
 * ----------
 */
static int	datums_alloc;
int			plpgsql_nDatums;
PLpgSQL_datum **plpgsql_Datums;
static int	datums_last = 0;

int			plpgsql_error_lineno;
char	   *plpgsql_error_funcname;
int			plpgsql_DumpExecTree = 0;

PLpgSQL_function *plpgsql_curr_compile;

/* ----------
 * Hash table for compiled functions
 * ----------
 */
static HTAB *plpgsql_HashTable = (HTAB *) NULL;

typedef struct plpgsql_hashent
{
	PLpgSQL_func_hashkey key;
	PLpgSQL_function *function;
}	plpgsql_HashEnt;

#define FUNCS_PER_USER		128 /* initial table size */


/* ----------
 * static prototypes
 * ----------
 */
static PLpgSQL_function *do_compile(FunctionCallInfo fcinfo,
		   HeapTuple procTup,
		   PLpgSQL_func_hashkey *hashkey);
static void plpgsql_compile_error_callback(void *arg);
static PLpgSQL_type *build_datatype(HeapTuple typeTup, int32 typmod);
static void compute_function_hashkey(FunctionCallInfo fcinfo,
						 Form_pg_proc procStruct,
						 PLpgSQL_func_hashkey *hashkey);
static PLpgSQL_function *plpgsql_HashTableLookup(PLpgSQL_func_hashkey *func_key);
static void plpgsql_HashTableInsert(PLpgSQL_function *function,
						PLpgSQL_func_hashkey *func_key);
static void plpgsql_HashTableDelete(PLpgSQL_function *function);

/*
 * This routine is a crock, and so is everyplace that calls it.  The problem
 * is that the compiled form of a plpgsql function 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);
}


/* ----------
 * plpgsql_compile		Make an execution tree for a PL/pgSQL function.
 *
 * Note: it's important for this to fall through quickly if the function
 * has already been compiled.
 * ----------
 */
PLpgSQL_function *
plpgsql_compile(FunctionCallInfo fcinfo)
{
	Oid			funcOid = fcinfo->flinfo->fn_oid;
	HeapTuple	procTup;
	Form_pg_proc procStruct;
	PLpgSQL_function *function;
	PLpgSQL_func_hashkey hashkey;
	bool		hashkey_valid = false;

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

	/*
	 * See if there's already a cache entry for the current FmgrInfo. If
	 * not, try to find one in the hash table.
	 */
	function = (PLpgSQL_function *) fcinfo->flinfo->fn_extra;

	if (!function)
	{
		/* First time through in this backend?	If so, init hashtable */
		if (!plpgsql_HashTable)
			plpgsql_HashTableInit();

		/* Compute hashkey using function signature and actual arg types */
		compute_function_hashkey(fcinfo, procStruct, &hashkey);
		hashkey_valid = true;

		/* And do the lookup */
		function = plpgsql_HashTableLookup(&hashkey);
	}

	if (function)
	{
		/* We have a compiled function, but is it still valid? */
		if (!(function->fn_xmin == HeapTupleHeaderGetXmin(procTup->t_data) &&
		   function->fn_cmin == HeapTupleHeaderGetCmin(procTup->t_data)))
		{
			/*
			 * Nope, drop the hashtable entry.	XXX someday, free all the
			 * subsidiary storage as well.
			 */
			plpgsql_HashTableDelete(function);

			function = NULL;
		}
	}

	/*
	 * If the function wasn't found or was out-of-date, we have to compile
	 * it
	 */
	if (!function)
	{
		/*
		 * Calculate hashkey if we didn't already; we'll need it to store
		 * the completed function.
		 */
		if (!hashkey_valid)
			compute_function_hashkey(fcinfo, procStruct, &hashkey);

		/*
		 * Do the hard part.
		 */
		function = do_compile(fcinfo, procTup, &hashkey);
	}

	ReleaseSysCache(procTup);

	/*
	 * Save pointer in FmgrInfo to avoid search on subsequent calls
	 */
	fcinfo->flinfo->fn_extra = (void *) function;

	/*
	 * Finally return the compiled function
	 */
	return function;
}

/*
 * This is the slow part of plpgsql_compile().
 */
static PLpgSQL_function *
do_compile(FunctionCallInfo fcinfo,
		   HeapTuple procTup,
		   PLpgSQL_func_hashkey *hashkey)
{
	Form_pg_proc procStruct = (Form_pg_proc) GETSTRUCT(procTup);
	int			functype = CALLED_AS_TRIGGER(fcinfo) ? T_TRIGGER : T_FUNCTION;
	PLpgSQL_function *function;
	char	   *proc_source;
	HeapTuple	typeTup;
	Form_pg_type typeStruct;
	PLpgSQL_var *var;
	PLpgSQL_row *row;
	PLpgSQL_rec *rec;
	int			i;
	int			arg_varnos[FUNC_MAX_ARGS];
	ErrorContextCallback plerrcontext;
	int			parse_rc;
	Oid			rettypeid;

	/*
	 * Setup the scanner input and error info.	We assume that this
	 * function cannot be invoked recursively, so there's no need to save
	 * and restore the static variables used here.
	 */
	proc_source = DatumGetCString(DirectFunctionCall1(textout,
								  PointerGetDatum(&procStruct->prosrc)));
	plpgsql_scanner_init(proc_source, functype);
	pfree(proc_source);

	plpgsql_error_funcname = pstrdup(NameStr(procStruct->proname));
	plpgsql_error_lineno = 0;

	/*
	 * Setup error traceback support for ereport()
	 */
	plerrcontext.callback = plpgsql_compile_error_callback;
	plerrcontext.arg = NULL;
	plerrcontext.previous = error_context_stack;
	error_context_stack = &plerrcontext;

	/*
	 * Initialize the compiler
	 */
	plpgsql_ns_init();
	plpgsql_ns_push(NULL);
	plpgsql_DumpExecTree = 0;

	datums_alloc = 128;
	plpgsql_nDatums = 0;
	plpgsql_Datums = palloc(sizeof(PLpgSQL_datum *) * datums_alloc);
	datums_last = 0;

	/*
	 * Create the new function node
	 */
	function = malloc(sizeof(PLpgSQL_function));
	MemSet(function, 0, sizeof(PLpgSQL_function));
	plpgsql_curr_compile = function;

	function->fn_name = strdup(NameStr(procStruct->proname));
	function->fn_oid = fcinfo->flinfo->fn_oid;
	function->fn_xmin = HeapTupleHeaderGetXmin(procTup->t_data);
	function->fn_cmin = HeapTupleHeaderGetCmin(procTup->t_data);
	function->fn_functype = functype;

	switch (functype)
	{
		case T_FUNCTION:

			/*
			 * Check for a polymorphic returntype. If found, use the
			 * actual returntype type from the caller's FuncExpr node, if
			 * we have one.
			 *
			 * Note: errcode is FEATURE_NOT_SUPPORTED because it should
			 * always work; if it doesn't we're in some context that fails
			 * to make the info available.
			 */
			rettypeid = procStruct->prorettype;
			if (rettypeid == ANYARRAYOID || rettypeid == ANYELEMENTOID)
			{
				rettypeid = get_fn_expr_rettype(fcinfo->flinfo);
				if (!OidIsValid(rettypeid))
					ereport(ERROR,
							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("could not determine actual return type "
								"for polymorphic function \"%s\"",
								plpgsql_error_funcname)));
			}

			/*
			 * Normal function has a defined returntype
			 */
			function->fn_rettype = rettypeid;
			function->fn_retset = procStruct->proretset;

			/*
			 * Lookup the functions return type
			 */
			typeTup = SearchSysCache(TYPEOID,
									 ObjectIdGetDatum(rettypeid),
									 0, 0, 0);
			if (!HeapTupleIsValid(typeTup))
				elog(ERROR, "cache lookup failed for type %u", rettypeid);
			typeStruct = (Form_pg_type) GETSTRUCT(typeTup);

			/* Disallow pseudotype result, except VOID or RECORD */
			/* (note we already replaced ANYARRAY/ANYELEMENT) */
			if (typeStruct->typtype == 'p')
			{
				if (rettypeid == VOIDOID ||
					rettypeid == RECORDOID)
					 /* okay */ ;
				else if (rettypeid == TRIGGEROID)
					ereport(ERROR,
							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
							 errmsg("trigger functions may only be called as triggers")));
				else
					ereport(ERROR,
							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						errmsg("plpgsql functions cannot return type %s",
							   format_type_be(rettypeid))));
			}

			if (typeStruct->typrelid != InvalidOid ||
				rettypeid == RECORDOID)
				function->fn_retistuple = true;
			else
			{
				function->fn_retbyval = typeStruct->typbyval;
				function->fn_rettyplen = typeStruct->typlen;
				function->fn_rettypelem = typeStruct->typelem;
				perm_fmgr_info(typeStruct->typinput, &(function->fn_retinput));

				/*
				 * install $0 reference, but only for polymorphic return
				 * types
				 */
				if (procStruct->prorettype == ANYARRAYOID ||
					procStruct->prorettype == ANYELEMENTOID)
				{
					char		buf[32];

					/* name for variable */
					snprintf(buf, sizeof(buf), "$%d", 0);

					/*
					 * Normal return values get a var node
					 */
					var = malloc(sizeof(PLpgSQL_var));
					memset(var, 0, sizeof(PLpgSQL_var));

					var->dtype = PLPGSQL_DTYPE_VAR;
					var->refname = strdup(buf);
					var->lineno = 0;
					var->datatype = build_datatype(typeTup, -1);
					var->isconst = false;
					var->notnull = false;
					var->default_val = NULL;

					/* preset to NULL */
					var->value = 0;
					var->isnull = true;
					var->freeval = false;

					plpgsql_adddatum((PLpgSQL_datum *) var);
					plpgsql_ns_additem(PLPGSQL_NSTYPE_VAR, var->varno,
									   var->refname);
				}
			}
			ReleaseSysCache(typeTup);

			/*
			 * Create the variables for the procedure's parameters
			 */
			for (i = 0; i < procStruct->pronargs; i++)
			{
				char		buf[32];
				Oid			argtypeid;

				/* name for variable */
				snprintf(buf, sizeof(buf), "$%d", i + 1);

				/*
				 * Since we already did the replacement of polymorphic
				 * argument types by actual argument types while computing
				 * the hashkey, we can just use those results.
				 */
				argtypeid = hashkey->argtypes[i];

				/*
				 * Get the parameters type
				 */
				typeTup = SearchSysCache(TYPEOID,
										 ObjectIdGetDatum(argtypeid),
										 0, 0, 0);
				if (!HeapTupleIsValid(typeTup))
					elog(ERROR, "cache lookup failed for type %u", argtypeid);
				typeStruct = (Form_pg_type) GETSTRUCT(typeTup);

				/* Disallow pseudotype argument */
				/* (note we already replaced ANYARRAY/ANYELEMENT) */
				if (typeStruct->typtype == 'p')
					ereport(ERROR,
							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						  errmsg("plpgsql functions cannot take type %s",
								 format_type_be(argtypeid))));

				if (typeStruct->typrelid != InvalidOid)
				{
					/*
					 * For tuple type parameters, we set up a record of
					 * that type
					 */
					row = plpgsql_build_rowtype(typeStruct->typrelid);

					row->refname = strdup(buf);

					plpgsql_adddatum((PLpgSQL_datum *) row);
					plpgsql_ns_additem(PLPGSQL_NSTYPE_ROW, row->rowno,
									   row->refname);

					arg_varnos[i] = row->rowno;
				}
				else
				{
					/*
					 * Normal parameters get a var node
					 */
					var = malloc(sizeof(PLpgSQL_var));
					memset(var, 0, sizeof(PLpgSQL_var));

					var->dtype = PLPGSQL_DTYPE_VAR;
					var->refname = strdup(buf);
					var->lineno = 0;
					var->datatype = build_datatype(typeTup, -1);
					var->isconst = true;
					var->notnull = false;
					var->default_val = NULL;

					plpgsql_adddatum((PLpgSQL_datum *) var);
					plpgsql_ns_additem(PLPGSQL_NSTYPE_VAR, var->varno,
									   var->refname);

					arg_varnos[i] = var->varno;
				}
				ReleaseSysCache(typeTup);
			}
			break;

		case T_TRIGGER:

			/*
			 * Trigger procedures return type is unknown yet
			 */
			function->fn_rettype = InvalidOid;
			function->fn_retbyval = false;
			function->fn_retistuple = true;
			function->fn_retset = false;

			/*
			 * Add the record for referencing NEW
			 */
			rec = malloc(sizeof(PLpgSQL_rec));
			memset(rec, 0, sizeof(PLpgSQL_rec));
			rec->dtype = PLPGSQL_DTYPE_REC;
			rec->refname = strdup("new");
			rec->tup = NULL;
			rec->tupdesc = NULL;
			rec->freetup = false;
			plpgsql_adddatum((PLpgSQL_datum *) rec);
			plpgsql_ns_additem(PLPGSQL_NSTYPE_REC, rec->recno, rec->refname);
			function->new_varno = rec->recno;

			/*
			 * Add the record for referencing OLD
			 */
			rec = malloc(sizeof(PLpgSQL_rec));
			memset(rec, 0, sizeof(PLpgSQL_rec));
			rec->dtype = PLPGSQL_DTYPE_REC;
			rec->refname = strdup("old");
			rec->tup = NULL;
			rec->tupdesc = NULL;
			rec->freetup = false;
			plpgsql_adddatum((PLpgSQL_datum *) rec);
			plpgsql_ns_additem(PLPGSQL_NSTYPE_REC, rec->recno, rec->refname);
			function->old_varno = rec->recno;

			/*
			 * Add the variable tg_name
			 */
			var = malloc(sizeof(PLpgSQL_var));
			memset(var, 0, sizeof(PLpgSQL_var));

			var->dtype = PLPGSQL_DTYPE_VAR;
			var->refname = strdup("tg_name");
			var->lineno = 0;
			var->datatype = plpgsql_parse_datatype("name");
			var->isconst = false;
			var->notnull = false;
			var->default_val = NULL;

			plpgsql_adddatum((PLpgSQL_datum *) var);
			plpgsql_ns_additem(PLPGSQL_NSTYPE_VAR, var->varno, var->refname);
			function->tg_name_varno = var->varno;

			/*
			 * Add the variable tg_when
			 */
			var = malloc(sizeof(PLpgSQL_var));
			memset(var, 0, sizeof(PLpgSQL_var));

			var->dtype = PLPGSQL_DTYPE_VAR;
			var->refname = strdup("tg_when");
			var->lineno = 0;
			var->datatype = plpgsql_parse_datatype("text");
			var->isconst = false;
			var->notnull = false;
			var->default_val = NULL;

			plpgsql_adddatum((PLpgSQL_datum *) var);
			plpgsql_ns_additem(PLPGSQL_NSTYPE_VAR, var->varno, var->refname);
			function->tg_when_varno = var->varno;

			/*
			 * Add the variable tg_level
			 */
			var = malloc(sizeof(PLpgSQL_var));
			memset(var, 0, sizeof(PLpgSQL_var));

			var->dtype = PLPGSQL_DTYPE_VAR;
			var->refname = strdup("tg_level");
			var->lineno = 0;
			var->datatype = plpgsql_parse_datatype("text");
			var->isconst = false;
			var->notnull = false;
			var->default_val = NULL;

			plpgsql_adddatum((PLpgSQL_datum *) var);
			plpgsql_ns_additem(PLPGSQL_NSTYPE_VAR, var->varno, var->refname);
			function->tg_level_varno = var->varno;

			/*
			 * Add the variable tg_op
			 */
			var = malloc(sizeof(PLpgSQL_var));
			memset(var, 0, sizeof(PLpgSQL_var));

			var->dtype = PLPGSQL_DTYPE_VAR;
			var->refname = strdup("tg_op");
			var->lineno = 0;
			var->datatype = plpgsql_parse_datatype("text");
			var->isconst = false;
			var->notnull = false;
			var->default_val = NULL;

			plpgsql_adddatum((PLpgSQL_datum *) var);
			plpgsql_ns_additem(PLPGSQL_NSTYPE_VAR, var->varno, var->refname);
			function->tg_op_varno = var->varno;

			/*
			 * Add the variable tg_relid
			 */
			var = malloc(sizeof(PLpgSQL_var));
			memset(var, 0, sizeof(PLpgSQL_var));

			var->dtype = PLPGSQL_DTYPE_VAR;
			var->refname = strdup("tg_relid");
			var->lineno = 0;
			var->datatype = plpgsql_parse_datatype("oid");
			var->isconst = false;
			var->notnull = false;
			var->default_val = NULL;

			plpgsql_adddatum((PLpgSQL_datum *) var);
			plpgsql_ns_additem(PLPGSQL_NSTYPE_VAR, var->varno, var->refname);
			function->tg_relid_varno = var->varno;

			/*
			 * Add the variable tg_relname
			 */
			var = malloc(sizeof(PLpgSQL_var));
			memset(var, 0, sizeof(PLpgSQL_var));