pl_exec.c

PostgreSQL7.4.6 for Linux

		estate->retval = (Datum) 0;
		estate->rettupdesc = NULL;
		estate->retisnull = true;

		if (stmt->retrecno >= 0)
		{
			PLpgSQL_rec *rec = (PLpgSQL_rec *) (estate->datums[stmt->retrecno]);

			if (HeapTupleIsValid(rec->tup))
			{
				estate->retval = (Datum) rec->tup;
				estate->rettupdesc = rec->tupdesc;
				estate->retisnull = false;
			}
			return PLPGSQL_RC_RETURN;
		}

		if (stmt->retrowno >= 0)
		{
			PLpgSQL_row *row = (PLpgSQL_row *) (estate->datums[stmt->retrowno]);

			if (row->rowtupdesc) /* should always be true here */
			{
				estate->retval = (Datum) make_tuple_from_row(estate, row,
															 row->rowtupdesc);
				if (estate->retval == (Datum) NULL)	/* should not happen */
					elog(ERROR, "row not compatible with its own tupdesc");
				estate->rettupdesc = row->rowtupdesc;
				estate->retisnull = false;
			}
			return PLPGSQL_RC_RETURN;
		}

		if (stmt->expr != NULL)
		{
			exec_run_select(estate, stmt->expr, 1, NULL);
			if (estate->eval_processed > 0)
			{
				estate->retval = (Datum) estate->eval_tuptable->vals[0];
				estate->rettupdesc = estate->eval_tuptable->tupdesc;
				estate->retisnull = false;
			}
		}
		return PLPGSQL_RC_RETURN;
	}

	if (estate->fn_rettype == VOIDOID)
	{
		/* Special hack for function returning VOID */
		estate->retval = (Datum) 0;
		estate->retisnull = false;
		estate->rettype = VOIDOID;
	}
	else
	{
		/* Normal case for scalar results */
		estate->retval = exec_eval_expr(estate, stmt->expr,
										&(estate->retisnull),
										&(estate->rettype));
	}

	return PLPGSQL_RC_RETURN;
}

/* ----------
 * exec_stmt_return_next		Evaluate an expression and add it to the
 *								list of tuples returned by the current
 *								SRF.
 * ----------
 */
static int
exec_stmt_return_next(PLpgSQL_execstate * estate,
					  PLpgSQL_stmt_return_next * stmt)
{
	TupleDesc	tupdesc;
	int			natts;
	HeapTuple	tuple;
	bool		free_tuple = false;

	if (!estate->retisset)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
			  errmsg("cannot use RETURN NEXT in a non-SETOF function")));

	if (estate->tuple_store == NULL)
		exec_init_tuple_store(estate);

	/* rettupdesc will be filled by exec_init_tuple_store */
	tupdesc = estate->rettupdesc;
	natts = tupdesc->natts;

	if (stmt->rec)
	{
		PLpgSQL_rec *rec = (PLpgSQL_rec *) (estate->datums[stmt->rec->recno]);

		if (!HeapTupleIsValid(rec->tup))
			ereport(ERROR,
					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
					 errmsg("record \"%s\" is not assigned yet",
							rec->refname),
					 errdetail("The tuple structure of a not-yet-assigned record is indeterminate.")));
		if (!compatible_tupdesc(tupdesc, rec->tupdesc))
			ereport(ERROR,
					(errcode(ERRCODE_DATATYPE_MISMATCH),
				   errmsg("wrong record type supplied in RETURN NEXT")));
		tuple = rec->tup;
	}
	else if (stmt->row)
	{
		tuple = make_tuple_from_row(estate, stmt->row, tupdesc);
		if (tuple == NULL)
			ereport(ERROR,
					(errcode(ERRCODE_DATATYPE_MISMATCH),
					 errmsg("wrong record type supplied in RETURN NEXT")));
		free_tuple = true;
	}
	else if (stmt->expr)
	{
		Datum		retval;
		bool		isNull;
		Oid			rettype;
		char		nullflag;

		if (natts != 1)
			ereport(ERROR,
					(errcode(ERRCODE_DATATYPE_MISMATCH),
				   errmsg("wrong result type supplied in RETURN NEXT")));

		retval = exec_eval_expr(estate,
								stmt->expr,
								&isNull,
								&rettype);

		/* coerce type if needed */
		retval = exec_simple_cast_value(retval,
										rettype,
										tupdesc->attrs[0]->atttypid,
										tupdesc->attrs[0]->atttypmod,
										&isNull);

		nullflag = isNull ? 'n' : ' ';

		tuple = heap_formtuple(tupdesc, &retval, &nullflag);

		free_tuple = true;

		exec_eval_cleanup(estate);
	}
	else
	{
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("RETURN NEXT must have a parameter")));
		tuple = NULL;			/* keep compiler quiet */
	}

	if (HeapTupleIsValid(tuple))
	{
		MemoryContext oldcxt;

		oldcxt = MemoryContextSwitchTo(estate->tuple_store_cxt);
		tuplestore_puttuple(estate->tuple_store, tuple);
		MemoryContextSwitchTo(oldcxt);

		if (free_tuple)
			heap_freetuple(tuple);
	}

	return PLPGSQL_RC_OK;
}

static void
exec_init_tuple_store(PLpgSQL_execstate * estate)
{
	ReturnSetInfo *rsi = estate->rsi;
	MemoryContext oldcxt;

	/*
	 * Check caller can handle a set result in the way we want
	 */
	if (!rsi || !IsA(rsi, ReturnSetInfo) ||
		(rsi->allowedModes & SFRM_Materialize) == 0 ||
		rsi->expectedDesc == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("set-valued function called in context that cannot accept a set")));

	estate->tuple_store_cxt = rsi->econtext->ecxt_per_query_memory;

	oldcxt = MemoryContextSwitchTo(estate->tuple_store_cxt);
	estate->tuple_store = tuplestore_begin_heap(true, false, SortMem);
	MemoryContextSwitchTo(oldcxt);

	estate->rettupdesc = rsi->expectedDesc;
}

/* ----------
 * exec_stmt_raise			Build a message and throw it with elog()
 * ----------
 */
static int
exec_stmt_raise(PLpgSQL_execstate * estate, PLpgSQL_stmt_raise * stmt)
{
	Oid			paramtypeid;
	Datum		paramvalue;
	bool		paramisnull;
	char	   *extval;
	int			pidx = 0;
	char		c[2] = {0, 0};
	char	   *cp;
	PLpgSQL_dstring ds;

	plpgsql_dstring_init(&ds);

	for (cp = stmt->message; *cp; cp++)
	{
		/*
		 * Occurences of a single % are replaced by the next argument's
		 * external representation. Double %'s are converted to one %.
		 */
		if ((c[0] = *cp) == '%')
		{
			cp++;
			if (*cp == '%')
			{
				plpgsql_dstring_append(&ds, c);
				continue;
			}
			cp--;
			if (pidx >= stmt->nparams)
			{
				plpgsql_dstring_append(&ds, c);
				continue;
			}
			exec_eval_datum(estate, estate->datums[stmt->params[pidx]],
							InvalidOid,
							&paramtypeid, &paramvalue, &paramisnull);
			if (paramisnull)
				extval = "<NULL>";
			else
				extval = convert_value_to_string(paramvalue, paramtypeid);
			plpgsql_dstring_append(&ds, extval);
			pidx++;
			continue;
		}

		/*
		 * Occurrences of single ' are removed. double ' are reduced to
		 * single ones.  We must do this because the parameter stored by
		 * the grammar is the raw T_STRING input literal, rather than the
		 * de-lexed string as you might expect ...
		 */
		if (*cp == '\'')
		{
			cp++;
			if (*cp == '\'')
				plpgsql_dstring_append(&ds, c);
			else
				cp--;
			continue;
		}
		plpgsql_dstring_append(&ds, c);
	}

	/*
	 * Throw the error (may or may not come back)
	 */
	estate->err_text = raise_skip_msg;	/* suppress traceback of raise */

	ereport(stmt->elog_level,
			(errmsg_internal("%s", plpgsql_dstring_get(&ds))));

	estate->err_text = NULL;	/* un-suppress... */

	plpgsql_dstring_free(&ds);

	return PLPGSQL_RC_OK;
}


/* ----------
 * Initialize a mostly empty execution state
 * ----------
 */
static void
plpgsql_estate_setup(PLpgSQL_execstate * estate,
					 PLpgSQL_function * func,
					 ReturnSetInfo *rsi)
{
	estate->retval = (Datum) 0;
	estate->retisnull = true;
	estate->rettype = InvalidOid;

	estate->fn_rettype = func->fn_rettype;
	estate->retistuple = func->fn_retistuple;
	estate->retisset = func->fn_retset;

	estate->rettupdesc = NULL;
	estate->exitlabel = NULL;

	estate->tuple_store = NULL;
	estate->tuple_store_cxt = NULL;
	estate->rsi = rsi;

	estate->trig_nargs = 0;
	estate->trig_argv = NULL;

	estate->found_varno = func->found_varno;
	estate->ndatums = func->ndatums;
	estate->datums = palloc(sizeof(PLpgSQL_datum *) * estate->ndatums);
	/* caller is expected to fill the datums array */

	estate->eval_tuptable = NULL;
	estate->eval_processed = 0;
	estate->eval_lastoid = InvalidOid;
	estate->eval_econtext = NULL;

	estate->err_func = func;
	estate->err_stmt = NULL;
	estate->err_text = NULL;
}

/* ----------
 * Release temporary memory used by expression/subselect evaluation
 *
 * NB: the result of the evaluation is no longer valid after this is done,
 * unless it is a pass-by-value datatype.
 * ----------
 */
static void
exec_eval_cleanup(PLpgSQL_execstate * estate)
{
	/* Clear result of a full SPI_exec */
	if (estate->eval_tuptable != NULL)
		SPI_freetuptable(estate->eval_tuptable);
	estate->eval_tuptable = NULL;

	/* Clear result of exec_eval_simple_expr (but keep the econtext) */
	if (estate->eval_econtext != NULL)
		ResetExprContext(estate->eval_econtext);
}


/* ----------
 * Generate a prepared plan
 * ----------
 */
static void
exec_prepare_plan(PLpgSQL_execstate * estate,
				  PLpgSQL_expr * expr)
{
	int			i;
	_SPI_plan  *spi_plan;
	void	   *plan;
	Oid		   *argtypes;

	/*
	 * We need a temporary argtypes array to load with data. (The finished
	 * plan structure will contain a copy of it.)
	 *
	 * +1 is just to avoid palloc(0) error.
	 */
	argtypes = (Oid *) palloc(sizeof(Oid) * (expr->nparams + 1));

	for (i = 0; i < expr->nparams; i++)
	{
		Datum		paramval;
		bool		paramisnull;

		exec_eval_datum(estate, estate->datums[expr->params[i]],
						InvalidOid,
						&argtypes[i], &paramval, &paramisnull);
	}

	/*
	 * Generate and save the plan
	 */
	plan = SPI_prepare(expr->query, expr->nparams, argtypes);
	if (plan == NULL)
		elog(ERROR, "SPI_prepare() failed on \"%s\"", expr->query);
	expr->plan = SPI_saveplan(plan);
	spi_plan = (_SPI_plan *) expr->plan;
	expr->plan_argtypes = spi_plan->argtypes;
	expr->expr_simple_expr = NULL;
	exec_simple_check_plan(expr);

	SPI_freeplan(plan);
	pfree(argtypes);
}


/* ----------
 * exec_stmt_execsql			Execute an SQL statement not
 *					returning any data.
 * ----------
 */
static int
exec_stmt_execsql(PLpgSQL_execstate * estate,
				  PLpgSQL_stmt_execsql * stmt)
{
	int			i;
	Datum	   *values;
	char	   *nulls;
	int			rc;
	PLpgSQL_expr *expr = stmt->sqlstmt;

	/*
	 * On the first call for this expression generate the plan
	 */
	if (expr->plan == NULL)
		exec_prepare_plan(estate, expr);

	/*
	 * Now build up the values and nulls arguments for SPI_execp()
	 */
	values = palloc(sizeof(Datum) * (expr->nparams + 1));
	nulls = palloc(expr->nparams + 1);

	for (i = 0; i < expr->nparams; i++)
	{
		PLpgSQL_datum *datum = estate->datums[expr->params[i]];
		Oid			paramtypeid;
		bool		paramisnull;

		exec_eval_datum(estate, datum, expr->plan_argtypes[i],
						&paramtypeid, &values[i], &paramisnull);
		if (paramisnull)
			nulls[i] = 'n';
		else
			nulls[i] = ' ';
	}

	/*
	 * Execute the plan
	 */
	rc = SPI_execp(expr->plan, values, nulls, 0);
	switch (rc)
	{
		case SPI_OK_UTILITY:
		case SPI_OK_SELINTO:
			break;

		case SPI_OK_INSERT:
		case SPI_OK_DELETE:
		case SPI_OK_UPDATE:

			/*
			 * If the INSERT, DELETE, or UPDATE query affected at least
			 * one tuple, set the magic 'FOUND' variable to true. This
			 * conforms with the behavior of PL/SQL.
			 */
			exec_set_found(estate, (SPI_processed != 0));
			break;

		case SPI_OK_SELECT:
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
			   errmsg("SELECT query has no destination for result data"),
					 errhint("If you want to discard the results, use PERFORM instead.")));

		default:
			elog(ERROR, "error executing query \"%s\"", expr->query);
	}

	/*
	 * Release any result tuples from SPI_execp (probably shouldn't be
	 * any)
	 */
	SPI_freetuptable(SPI_tuptable);

	/* Save result info for GET DIAGNOSTICS */
	estate->eval_processed = SPI_processed;
	estate->eval_lastoid = SPI_lastoid;

	pfree(values);
	pfree(nulls);

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_dynexecute			Execute a dynamic SQL query not
 *					returning any data.
 * ----------
 */
static int
exec_stmt_dynexecute(PLpgSQL_execstate * estate,
					 PLpgSQL_stmt_dynexecute * stmt)
{
	Datum		query;
	bool		isnull = false;
	Oid			restype;
	char	   *querystr;
	int			exec_res;

	/*
	 * First we evaluate the string expression after the EXECUTE keyword.
	 * It's result is the querystring we have to execute.
	 */
	query = exec_eval_expr(estate, stmt->query, &isnull, &restype);
	if (isnull)
		ereport(ERROR,
				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
				 errmsg("cannot EXECUTE a null querystring")));

	/* Get the C-String representation */
	querystr = convert_value_to_string(query, restype);

	exec_eval_cleanup(estate);

	/*
	 * Call SPI_exec() without preparing a saved plan. The returncode can
	 * be any standard OK.	Note that while a SELECT is allowed, its
	 * results will be discarded.
	 */
	exec_res = SPI_exec(querystr, 0);
	switch (exec_res)
	{
		case SPI_OK_SELECT:
		case SPI_OK_INSERT:
		case SPI_OK_UPDATE:
		case SPI_OK_DELETE:
		case SPI_OK_UTILITY:
			break;

		case 0:

			/*
			 * Also allow a zero return, which implies the querystring