pl_exec.c

关系型数据库 Postgresql 6.5.2

/**********************************************************************
 * pl_exec.c		- Executor for the PL/pgSQL
 *			  procedural language
 *
 * IDENTIFICATION
 *	  $Header: /usr/local/cvsroot/pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.12 1999/07/04 01:03:01 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 <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <ctype.h>
#include <setjmp.h>

#include "plpgsql.h"
#include "pl.tab.h"

#include "executor/spi.h"
#include "executor/spi_priv.h"
#include "commands/trigger.h"
#include "utils/elog.h"
#include "utils/builtins.h"
#include "fmgr.h"
#include "access/heapam.h"

#include "tcop/tcopprot.h"
#include "utils/syscache.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"


static PLpgSQL_function *error_info_func = NULL;
static PLpgSQL_stmt *error_info_stmt = NULL;
static char *error_info_text = NULL;


/************************************************************
 * Local function forward declarations
 ************************************************************/
static PLpgSQL_var *copy_var(PLpgSQL_var * var);
static PLpgSQL_rec *copy_rec(PLpgSQL_rec * rec);

static int exec_stmt_block(PLpgSQL_execstate * estate,
				PLpgSQL_stmt_block * block);
static int exec_stmts(PLpgSQL_execstate * estate,
		   PLpgSQL_stmts * stmts);
static int exec_stmt(PLpgSQL_execstate * estate,
		  PLpgSQL_stmt * stmt);
static int exec_stmt_assign(PLpgSQL_execstate * estate,
				 PLpgSQL_stmt_assign * stmt);
static int exec_stmt_if(PLpgSQL_execstate * estate,
			 PLpgSQL_stmt_if * stmt);
static int exec_stmt_loop(PLpgSQL_execstate * estate,
			   PLpgSQL_stmt_loop * stmt);
static int exec_stmt_while(PLpgSQL_execstate * estate,
				PLpgSQL_stmt_while * stmt);
static int exec_stmt_fori(PLpgSQL_execstate * estate,
			   PLpgSQL_stmt_fori * stmt);
static int exec_stmt_fors(PLpgSQL_execstate * estate,
			   PLpgSQL_stmt_fors * stmt);
static int exec_stmt_select(PLpgSQL_execstate * estate,
				 PLpgSQL_stmt_select * stmt);
static int exec_stmt_exit(PLpgSQL_execstate * estate,
			   PLpgSQL_stmt_exit * stmt);
static int exec_stmt_return(PLpgSQL_execstate * estate,
				 PLpgSQL_stmt_return * stmt);
static int exec_stmt_raise(PLpgSQL_execstate * estate,
				PLpgSQL_stmt_raise * stmt);
static int exec_stmt_execsql(PLpgSQL_execstate * estate,
				  PLpgSQL_stmt_execsql * stmt);

static void exec_prepare_plan(PLpgSQL_execstate * estate,
				  PLpgSQL_expr * expr);
static bool exec_simple_check_node(Node *node);
static void exec_simple_check_plan(PLpgSQL_expr * expr);
static void exec_eval_clear_fcache(Node *node);
static Datum exec_eval_simple_expr(PLpgSQL_execstate * estate,
					  PLpgSQL_expr * expr,
					  bool *isNull,
					  Oid *rettype);

static void exec_assign_expr(PLpgSQL_execstate * estate,
				 PLpgSQL_datum * target,
				 PLpgSQL_expr * expr);
static void exec_assign_value(PLpgSQL_execstate * estate,
				  PLpgSQL_datum * target,
				  Datum value, Oid valtype, bool *isNull);
static Datum exec_eval_expr(PLpgSQL_execstate * estate,
			   PLpgSQL_expr * expr,
			   bool *isNull,
			   Oid *rettype);
static int exec_run_select(PLpgSQL_execstate * estate,
				PLpgSQL_expr * expr, int maxtuples);
static void exec_move_row(PLpgSQL_execstate * estate,
			  PLpgSQL_rec * rec,
			  PLpgSQL_row * row,
			  HeapTuple tup, TupleDesc tupdesc);
static Datum exec_cast_value(Datum value, Oid valtype,
				Oid reqtype,
				FmgrInfo *reqinput,
				int16 reqtypmod,
				bool *isnull);
static void exec_set_found(PLpgSQL_execstate * estate, bool state);


/* ----------
 * plpgsql_exec_function	Called by the call handler for
 *				function execution.
 * ----------
 */
Datum
plpgsql_exec_function(PLpgSQL_function * func,
					  FmgrValues *args, bool *isNull)
{
	PLpgSQL_execstate estate;
	int			i;
	sigjmp_buf	save_restart;
	PLpgSQL_function *save_efunc;
	PLpgSQL_stmt *save_estmt;
	char	   *save_etext;

	/* ----------
	 * Setup debug error info and catch elog()
	 * ----------
	 */
	save_efunc = error_info_func;
	save_estmt = error_info_stmt;
	save_etext = error_info_text;

	error_info_func = func;
	error_info_stmt = NULL;
	error_info_text = "while initialization of execution state";

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

		/* ----------
		 * If we are the first of cascaded error catchings,
		 * print where this happened
		 * ----------
		 */
		if (error_info_func != NULL)
		{
			elog(DEBUG, "Last error occured while executing PL/pgSQL function %s",
				 error_info_func->fn_name);
			if (error_info_stmt != NULL)
			{
				char	   *stmttype;

				switch (error_info_stmt->cmd_type)
				{
					case PLPGSQL_STMT_BLOCK:
						stmttype = "blocks variable initialization";
						break;
					case PLPGSQL_STMT_ASSIGN:
						stmttype = "assignment";
						break;
					case PLPGSQL_STMT_IF:
						stmttype = "if";
						break;
					case PLPGSQL_STMT_LOOP:
						stmttype = "loop";
						break;
					case PLPGSQL_STMT_WHILE:
						stmttype = "while";
						break;
					case PLPGSQL_STMT_FORI:
						stmttype = "for with integer loopvar";
						break;
					case PLPGSQL_STMT_FORS:
						stmttype = "for over select rows";
						break;
					case PLPGSQL_STMT_SELECT:
						stmttype = "select into variables";
						break;
					case PLPGSQL_STMT_EXIT:
						stmttype = "exit";
						break;
					case PLPGSQL_STMT_RETURN:
						stmttype = "return";
						break;
					case PLPGSQL_STMT_RAISE:
						stmttype = "raise";
						break;
					case PLPGSQL_STMT_EXECSQL:
						stmttype = "SQL statement";
						break;
					default:
						stmttype = "unknown";
						break;
				}
				elog(DEBUG, "line %d at %s", error_info_stmt->lineno,
					 stmttype);
			}
			else
			{
				if (error_info_text != NULL)
					elog(DEBUG, "%s", error_info_text);
				else
					elog(DEBUG, "no more error information available");
			}

			error_info_func = NULL;
			error_info_stmt = NULL;
			error_info_text = NULL;
		}

		siglongjmp(Warn_restart, 1);
	}


	/* ----------
	 * Setup the execution state
	 * ----------
	 */
	estate.retval = 0;
	estate.retisnull = false;
	estate.rettype = InvalidOid;
	estate.retistuple = func->fn_retistuple;
	estate.retisset = func->fn_retset;
	estate.exitlabel = NULL;

	estate.found_varno = func->found_varno;
	estate.ndatums = func->ndatums;
	estate.datums = palloc(sizeof(PLpgSQL_datum *) * estate.ndatums);

	/* ----------
	 * Make local execution copies of all the datums
	 * ----------
	 */
	for (i = 0; i < func->ndatums; i++)
	{
		switch (func->datums[i]->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				estate.datums[i] = (PLpgSQL_datum *)
					copy_var((PLpgSQL_var *) (func->datums[i]));
				break;

			case PLPGSQL_DTYPE_REC:
				estate.datums[i] = (PLpgSQL_datum *)
					copy_rec((PLpgSQL_rec *) (func->datums[i]));
				break;

			case PLPGSQL_DTYPE_ROW:
			case PLPGSQL_DTYPE_RECFIELD:
				estate.datums[i] = func->datums[i];
				break;

			default:
				elog(ERROR, "unknown dtype %d in plpgsql_exec_function()",
					 func->datums[i]->dtype);
		}
	}

	/* ----------
	 * Put the actual call argument values into the variables
	 * ----------
	 */
	error_info_text = "while putting call arguments to local variables";
	for (i = 0; i < func->fn_nargs; i++)
	{
		int			n = func->fn_argvarnos[i];

		switch (estate.datums[n]->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				{
					PLpgSQL_var *var = (PLpgSQL_var *) estate.datums[n];

					var->value = (Datum) (args->data[i]);
					var->isnull = *isNull;
					var->shouldfree = false;
				}
				break;

			case PLPGSQL_DTYPE_ROW:
				{
					HeapTuple	tup;
					TupleDesc	tupdesc;
					PLpgSQL_row *row = (PLpgSQL_row *) estate.datums[n];

					tup = ((TupleTableSlot *) (args->data[i]))->val;
					tupdesc = ((TupleTableSlot *) (args->data[i]))->ttc_tupleDescriptor;

					exec_move_row(&estate, NULL, row, tup, tupdesc);
				}
				break;

			default:
				elog(ERROR, "unknown dtype %d in plpgsql_exec_function()",
					 func->datums[i]->dtype);
		}
	}

	/* ----------
	 * Initialize the other variables to NULL values for now.
	 * The default values are set when the blocks are entered.
	 * ----------
	 */
	error_info_text = "while initializing local variables to NULL";
	for (i = estate.found_varno; i < estate.ndatums; i++)
	{
		switch (estate.datums[i]->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				{
					PLpgSQL_var *var = (PLpgSQL_var *) estate.datums[i];

					var->value = 0;
					var->isnull = true;
					var->shouldfree = false;
				}
				break;

			case PLPGSQL_DTYPE_ROW:
			case PLPGSQL_DTYPE_REC:
			case PLPGSQL_DTYPE_RECFIELD:
				break;

			default:
				elog(ERROR, "unknown dtype %d in plpgsql_exec_function()",
					 func->datums[i]->dtype);
		}
	}

	/* ----------
	 * Set the magic variable FOUND to false
	 * ----------
	 */
	exec_set_found(&estate, false);

	/* ----------
	 * Now call the toplevel block of statements
	 * ----------
	 */
	error_info_text = NULL;
	error_info_stmt = (PLpgSQL_stmt *) (func->action);
	if (exec_stmt_block(&estate, func->action) != PLPGSQL_RC_RETURN)
	{
		error_info_stmt = NULL;
		error_info_text = "at END of toplevel PL block";
		elog(ERROR, "control reaches end of function without RETURN");
	}

	/* ----------
	 * We got a return value - process it
	 * ----------
	 */
	error_info_stmt = NULL;
	error_info_text = "while casting return value to functions return type";

	*isNull = estate.retisnull;

	if (!estate.retistuple)
	{
		estate.retval = exec_cast_value(estate.retval, estate.rettype,
							  func->fn_rettype, &(func->fn_retinput), -1,
										isNull);

		/* ----------
		 * If the functions return type isn't by value,
		 * copy the value into upper executor memory context.
		 * ----------
		 */
		if (!*isNull && !func->fn_retbyval)
		{
			int			len;
			Datum		tmp;

			if (func->fn_rettyplen < 0)
				len = VARSIZE(estate.retval);
			else
				len = func->fn_rettyplen;

			tmp = (Datum) SPI_palloc(len);
			memcpy((void *) tmp, (void *) estate.retval, len);
			estate.retval = tmp;
		}
	}

	/* ----------
	 * Restore the previous error info and elog() jump target
	 * ----------
	 */
	error_info_func = save_efunc;
	error_info_stmt = save_estmt;
	error_info_text = save_etext;
	memcpy(&Warn_restart, &save_restart, sizeof(Warn_restart));

	/* ----------
	 * Return the functions result
	 * ----------
	 */
	return estate.retval;
}


/* ----------
 * plpgsql_exec_trigger		Called by the call handler for
 *				trigger execution.
 * ----------
 */
HeapTuple
plpgsql_exec_trigger(PLpgSQL_function * func,
					 TriggerData *trigdata)
{
	PLpgSQL_execstate estate;
	int			i;
	sigjmp_buf	save_restart;
	PLpgSQL_function *save_efunc;
	PLpgSQL_stmt *save_estmt;
	char	   *save_etext;
	PLpgSQL_rec *rec_new;
	PLpgSQL_rec *rec_old;
	PLpgSQL_var *var;
	HeapTuple	rettup;

	/* ----------
	 * Setup debug error info and catch elog()
	 * ----------
	 */
	save_efunc = error_info_func;
	save_estmt = error_info_stmt;
	save_etext = error_info_text;

	error_info_func = func;
	error_info_stmt = NULL;
	error_info_text = "while initialization of execution state";

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

		/* ----------
		 * If we are the first of cascaded error catchings,
		 * print where this happened
		 * ----------
		 */
		if (error_info_func != NULL)
		{
			elog(DEBUG, "Last error occured while executing PL/pgSQL function %s",
				 error_info_func->fn_name);
			if (error_info_stmt != NULL)
			{
				char	   *stmttype;

				switch (error_info_stmt->cmd_type)
				{
					case PLPGSQL_STMT_BLOCK:
						stmttype = "blocks variable initialization";
						break;
					case PLPGSQL_STMT_ASSIGN:
						stmttype = "assignment";
						break;
					case PLPGSQL_STMT_IF:
						stmttype = "if";
						break;
					case PLPGSQL_STMT_LOOP:
						stmttype = "loop";
						break;
					case PLPGSQL_STMT_WHILE:
						stmttype = "while";
						break;
					case PLPGSQL_STMT_FORI:
						stmttype = "for with integer loopvar";
						break;
					case PLPGSQL_STMT_FORS:
						stmttype = "for over select rows";
						break;
					case PLPGSQL_STMT_SELECT:
						stmttype = "select into variables";
						break;
					case PLPGSQL_STMT_EXIT:
						stmttype = "exit";
						break;
					case PLPGSQL_STMT_RETURN:
						stmttype = "return";
						break;
					case PLPGSQL_STMT_RAISE:
						stmttype = "raise";
						break;
					case PLPGSQL_STMT_EXECSQL:
						stmttype = "SQL statement";
						break;
					default:
						stmttype = "unknown";
						break;
				}
				elog(DEBUG, "line %d at %s", error_info_stmt->lineno,
					 stmttype);
			}
			else
			{
				if (error_info_text != NULL)
					elog(DEBUG, "%s", error_info_text);
				else
					elog(DEBUG, "no more error information available");
			}

			error_info_func = NULL;
			error_info_stmt = NULL;
			error_info_text = NULL;
		}

		siglongjmp(Warn_restart, 1);
	}


	/* ----------
	 * Setup the execution state
	 * ----------
	 */
	estate.retval = 0;
	estate.retisnull = false;
	estate.rettype = InvalidOid;
	estate.retistuple = func->fn_retistuple;
	estate.retisset = func->fn_retset;
	estate.exitlabel = NULL;

	estate.found_varno = func->found_varno;
	estate.ndatums = func->ndatums;
	estate.datums = palloc(sizeof(PLpgSQL_datum *) * estate.ndatums);

	/* ----------
	 * Make local execution copies of all the datums
	 * ----------
	 */
	for (i = 0; i < func->ndatums; i++)
	{
		switch (func->datums[i]->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				estate.datums[i] = (PLpgSQL_datum *)
					copy_var((PLpgSQL_var *) (func->datums[i]));
				break;

			case PLPGSQL_DTYPE_REC:
				estate.datums[i] = (PLpgSQL_datum *)
					copy_rec((PLpgSQL_rec *) (func->datums[i]));
				break;

			case PLPGSQL_DTYPE_ROW:
			case PLPGSQL_DTYPE_RECFIELD:
			case PLPGSQL_DTYPE_TRIGARG:
				estate.datums[i] = func->datums[i];
				break;

			default:
				elog(ERROR, "unknown dtype %d in plpgsql_exec_function()",
					 func->datums[i]->dtype);
		}
	}

	/* ----------
	 * Put the trig and new tuples into the records
	 * and set the tg_op variable
	 * ----------
	 */
	rec_new = (PLpgSQL_rec *) (estate.datums[func->new_varno]);
	rec_old = (PLpgSQL_rec *) (estate.datums[func->old_varno]);
	var = (PLpgSQL_var *) (estate.datums[func->tg_op_varno]);
	var->isnull = false;

	if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
	{
		rec_new->tup = trigdata->tg_trigtuple;
		rec_new->tupdesc = trigdata->tg_relation->rd_att;
		rec_old->tup = NULL;
		rec_old->tupdesc = NULL;
		var->value = (Datum) textin("INSERT");
	}
	else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
	{
		rec_new->tup = trigdata->tg_newtuple;
		rec_new->tupdesc = trigdata->tg_relation->rd_att;
		rec_old->tup = trigdata->tg_trigtuple;
		rec_old->tupdesc = trigdata->tg_relation->rd_att;
		var->value = (Datum) textin("UPDATE");
	}
	else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
	{
		rec_new->tup = NULL;
		rec_new->tupdesc = NULL;
		rec_old->tup = trigdata->tg_trigtuple;
		rec_old->tupdesc = trigdata->tg_relation->rd_att;
		var->value = (Datum) textin("DELETE");
	}
	else
	{
		rec_new->tup = NULL;
		rec_new->tupdesc = NULL;
		var->value = (Datum) textin("UNKNOWN");
	}

	/* ----------
	 * Fill all the other special tg_ variables
	 * ----------
	 */
	var = (PLpgSQL_var *) (estate.datums[func->tg_name_varno]);
	var->isnull = false;
	var->value = (Datum) namein(trigdata->tg_trigger->tgname);

	var = (PLpgSQL_var *) (estate.datums[func->tg_when_varno]);
	var->isnull = false;
	if (TRIGGER_FIRED_BEFORE(trigdata->tg_event))
		var->value = (Datum) textin("BEFORE");
	else if (TRIGGER_FIRED_AFTER(trigdata->tg_event))
		var->value = (Datum) textin("AFTER");
	else
		var->value = (Datum) textin("UNKNOWN");

	var = (PLpgSQL_var *) (estate.datums[func->tg_level_varno]);
	var->isnull = false;
	if (TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
		var->value = (Datum) textin("ROW");