functioncmds.c

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/*-------------------------------------------------------------------------
 *
 * functioncmds.c
 *
 *	  Routines for CREATE and DROP FUNCTION commands
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/commands/functioncmds.c,v 1.38.2.1 2004/02/21 00:35:13 tgl Exp $
 *
 * DESCRIPTION
 *	  These routines take the parse tree and pick out the
 *	  appropriate arguments/flags, and pass the results to the
 *	  corresponding "FooDefine" routines (in src/catalog) that do
 *	  the actual catalog-munging.  These routines also verify permission
 *	  of the user to execute the command.
 *
 * NOTES
 *	  These things must be defined and committed in the following order:
 *		"create function":
 *				input/output, recv/send procedures
 *		"create type":
 *				type
 *		"create operator":
 *				operators
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/genam.h"
#include "access/heapam.h"
#include "catalog/catname.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/pg_cast.h"
#include "catalog/pg_language.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "miscadmin.h"
#include "optimizer/cost.h"
#include "parser/parse_func.h"
#include "parser/parse_type.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"


/*
 *	 Examine the "returns" clause returnType of the CREATE FUNCTION statement
 *	 and return information about it as *prorettype_p and *returnsSet.
 *
 * This is more complex than the average typename lookup because we want to
 * allow a shell type to be used, or even created if the specified return type
 * doesn't exist yet.  (Without this, there's no way to define the I/O procs
 * for a new type.)  But SQL function creation won't cope, so error out if
 * the target language is SQL.	(We do this here, not in the SQL-function
 * validator, so as not to produce a NOTICE and then an ERROR for the same
 * condition.)
 */
static void
compute_return_type(TypeName *returnType, Oid languageOid,
					Oid *prorettype_p, bool *returnsSet_p)
{
	Oid			rettype;

	rettype = LookupTypeName(returnType);

	if (OidIsValid(rettype))
	{
		if (!get_typisdefined(rettype))
		{
			if (languageOid == SQLlanguageId)
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
					   errmsg("SQL function cannot return shell type %s",
							  TypeNameToString(returnType))));
			else
				ereport(NOTICE,
						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
						 errmsg("return type %s is only a shell",
								TypeNameToString(returnType))));
		}
	}
	else
	{
		char	   *typnam = TypeNameToString(returnType);
		Oid			namespaceId;
		AclResult	aclresult;
		char	   *typname;

		/*
		 * Only C-coded functions can be I/O functions.  We enforce this
		 * restriction here mainly to prevent littering the catalogs with
		 * shell types due to simple typos in user-defined function
		 * definitions.
		 */
		if (languageOid != INTERNALlanguageId &&
			languageOid != ClanguageId)
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_OBJECT),
					 errmsg("type \"%s\" does not exist", typnam)));

		/* Otherwise, go ahead and make a shell type */
		ereport(NOTICE,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("type \"%s\" is not yet defined", typnam),
				 errdetail("Creating a shell type definition.")));
		namespaceId = QualifiedNameGetCreationNamespace(returnType->names,
														&typname);
		aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
										  ACL_CREATE);
		if (aclresult != ACLCHECK_OK)
			aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
						   get_namespace_name(namespaceId));
		rettype = TypeShellMake(typname, namespaceId);
		Assert(OidIsValid(rettype));
	}

	*prorettype_p = rettype;
	*returnsSet_p = returnType->setof;
}

/*
 * Interpret the argument-types list of the CREATE FUNCTION statement.
 */
static int
compute_parameter_types(List *argTypes, Oid languageOid,
						Oid *parameterTypes)
{
	int			parameterCount = 0;
	List	   *x;

	MemSet(parameterTypes, 0, FUNC_MAX_ARGS * sizeof(Oid));
	foreach(x, argTypes)
	{
		TypeName   *t = (TypeName *) lfirst(x);
		Oid			toid;

		if (parameterCount >= FUNC_MAX_ARGS)
			ereport(ERROR,
					(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
				   errmsg("functions cannot have more than %d arguments",
						  FUNC_MAX_ARGS)));

		toid = LookupTypeName(t);
		if (OidIsValid(toid))
		{
			if (!get_typisdefined(toid))
			{
				/* As above, hard error if language is SQL */
				if (languageOid == SQLlanguageId)
					ereport(ERROR,
							(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
					   errmsg("SQL function cannot accept shell type %s",
							  TypeNameToString(t))));
				else
					ereport(NOTICE,
							(errcode(ERRCODE_WRONG_OBJECT_TYPE),
							 errmsg("argument type %s is only a shell",
									TypeNameToString(t))));
			}
		}
		else
		{
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_OBJECT),
					 errmsg("type %s does not exist",
							TypeNameToString(t))));
		}

		if (t->setof)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
					 errmsg("functions cannot accept set arguments")));

		parameterTypes[parameterCount++] = toid;
	}

	return parameterCount;
}


/*
 * Dissect the list of options assembled in gram.y into function
 * attributes.
 */

static void
compute_attributes_sql_style(const List *options,
							 List **as,
							 char **language,
							 char *volatility_p,
							 bool *strict_p,
							 bool *security_definer)
{
	const List *option;
	DefElem    *as_item = NULL;
	DefElem    *language_item = NULL;
	DefElem    *volatility_item = NULL;
	DefElem    *strict_item = NULL;
	DefElem    *security_item = NULL;

	foreach(option, options)
	{
		DefElem    *defel = (DefElem *) lfirst(option);

		if (strcmp(defel->defname, "as") == 0)
		{
			if (as_item)
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
						 errmsg("conflicting or redundant options")));
			as_item = defel;
		}
		else if (strcmp(defel->defname, "language") == 0)
		{
			if (language_item)
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
						 errmsg("conflicting or redundant options")));
			language_item = defel;
		}
		else if (strcmp(defel->defname, "volatility") == 0)
		{
			if (volatility_item)
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
						 errmsg("conflicting or redundant options")));
			volatility_item = defel;
		}
		else if (strcmp(defel->defname, "strict") == 0)
		{
			if (strict_item)
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
						 errmsg("conflicting or redundant options")));
			strict_item = defel;
		}
		else if (strcmp(defel->defname, "security") == 0)
		{
			if (security_item)
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
						 errmsg("conflicting or redundant options")));
			security_item = defel;
		}
		else
			elog(ERROR, "option \"%s\" not recognized",
				 defel->defname);
	}

	if (as_item)
		*as = (List *) as_item->arg;
	else
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
				 errmsg("no function body specified")));

	if (language_item)
		*language = strVal(language_item->arg);
	else
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
				 errmsg("no language specified")));

	if (volatility_item)
	{
		if (strcmp(strVal(volatility_item->arg), "immutable") == 0)
			*volatility_p = PROVOLATILE_IMMUTABLE;
		else if (strcmp(strVal(volatility_item->arg), "stable") == 0)
			*volatility_p = PROVOLATILE_STABLE;
		else if (strcmp(strVal(volatility_item->arg), "volatile") == 0)
			*volatility_p = PROVOLATILE_VOLATILE;
		else
			elog(ERROR, "invalid volatility \"%s\"",
				 strVal(volatility_item->arg));
	}

	if (strict_item)
		*strict_p = intVal(strict_item->arg);
	if (security_item)
		*security_definer = intVal(security_item->arg);
}


/*-------------
 *	 Interpret the parameters *parameters and return their contents as
 *	 *byte_pct_p, etc.
 *
 *	These parameters supply optional information about a function.
 *	All have defaults if not specified.
 *
 *	Note: currently, only two of these parameters actually do anything:
 *
 *	 * isStrict means the function should not be called when any NULL
 *	   inputs are present; instead a NULL result value should be assumed.
 *
 *	 * volatility tells the optimizer whether the function's result can
 *	   be assumed to be repeatable over multiple evaluations.
 *
 *	The other four parameters are not used anywhere.	They used to be
 *	used in the "expensive functions" optimizer, but that's been dead code
 *	for a long time.
 *------------
 */
static void
compute_attributes_with_style(List *parameters, bool *isStrict_p, char *volatility_p)
{
	List	   *pl;

	foreach(pl, parameters)
	{
		DefElem    *param = (DefElem *) lfirst(pl);

		if (strcasecmp(param->defname, "isstrict") == 0)
			*isStrict_p = true;
		else if (strcasecmp(param->defname, "iscachable") == 0)
		{
			/* obsolete spelling of isImmutable */
			*volatility_p = PROVOLATILE_IMMUTABLE;
		}
		else
			ereport(WARNING,
					(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("unrecognized function attribute \"%s\" ignored",
						param->defname)));
	}
}


/*
 * For a dynamically linked C language object, the form of the clause is
 *
 *	   AS <object file name> [, <link symbol name> ]
 *
 * In all other cases
 *
 *	   AS <object reference, or sql code>
 *
 */

static void
interpret_AS_clause(Oid languageOid, const char *languageName, const List *as,
					char **prosrc_str_p, char **probin_str_p)
{
	Assert(as != NIL);

	if (languageOid == ClanguageId)
	{
		/*
		 * For "C" language, store the file name in probin and, when
		 * given, the link symbol name in prosrc.
		 */
		*probin_str_p = strVal(lfirst(as));
		if (lnext(as) == NULL)
			*prosrc_str_p = "-";
		else
			*prosrc_str_p = strVal(lsecond(as));
	}
	else
	{
		/* Everything else wants the given string in prosrc. */
		*prosrc_str_p = strVal(lfirst(as));
		*probin_str_p = "-";