functioncmds.c

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/*-------------------------------------------------------------------------
 *
 * functioncmds.c
 *
 *    Routines for CREATE and DROP FUNCTION commands and CREATE and DROP
 *    CAST commands.
 *
 * Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/commands/functioncmds.c
 *
 * 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 "access/htup_details.h"
#include "access/sysattr.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/objectaccess.h"
#include "catalog/pg_aggregate.h"
#include "catalog/pg_cast.h"
#include "catalog/pg_language.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_proc_fn.h"
#include "catalog/pg_transform.h"
#include "catalog/pg_type.h"
#include "catalog/pg_type_fn.h"
#include "commands/alter.h"
#include "commands/defrem.h"
#include "commands/proclang.h"
#include "miscadmin.h"
#include "optimizer/var.h"
#include "parser/parse_coerce.h"
#include "parser/parse_collate.h"
#include "parser/parse_expr.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/guc.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/syscache.h"
#include "utils/tqual.h"

/*
 *   Examine the RETURNS clause 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;
    Type        typtup;
    AclResult   aclresult;

    typtup = LookupTypeName(NULL, returnType, NULL, false);

    if (typtup)
    {
        if (!((Form_pg_type) GETSTRUCT(typtup))->typisdefined)
        {
            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))));
        }
        rettype = typeTypeId(typtup);
        ReleaseSysCache(typtup);
    }
    else
    {
        char       *typnam = TypeNameToString(returnType);
        Oid         namespaceId;
        AclResult   aclresult;
        char       *typname;
        ObjectAddress address;

        /*
         * 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)));

        /* Reject if there's typmod decoration, too */
        if (returnType->typmods != NIL)
            ereport(ERROR,
                    (errcode(ERRCODE_SYNTAX_ERROR),
            errmsg("type modifier cannot be specified for shell type \"%s\"",
                   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));
        address = TypeShellMake(typname, namespaceId, GetUserId());
        rettype = address.objectId;
        Assert(OidIsValid(rettype));
    }

    aclresult = pg_type_aclcheck(rettype, GetUserId(), ACL_USAGE);
    if (aclresult != ACLCHECK_OK)
        aclcheck_error_type(aclresult, rettype);

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

/*
 * Interpret the function parameter list of a CREATE FUNCTION or
 * CREATE AGGREGATE statement.
 *
 * Input parameters:
 * parameters: list of FunctionParameter structs
 * languageOid: OID of function language (InvalidOid if it's CREATE AGGREGATE)
 * is_aggregate: needed only to determine error handling
 * queryString: likewise, needed only for error handling
 *
 * Results are stored into output parameters.  parameterTypes must always
 * be created, but the other arrays are set to NULL if not needed.
 * variadicArgType is set to the variadic array type if there's a VARIADIC
 * parameter (there can be only one); or to InvalidOid if not.
 * requiredResultType is set to InvalidOid if there are no OUT parameters,
 * else it is set to the OID of the implied result type.
 */
void
interpret_function_parameter_list(List *parameters,
                                  Oid languageOid,
                                  bool is_aggregate,
                                  const char *queryString,
                                  oidvector **parameterTypes,
                                  ArrayType **allParameterTypes,
                                  ArrayType **parameterModes,
                                  ArrayType **parameterNames,
                                  List **parameterDefaults,
                                  Oid *variadicArgType,
                                  Oid *requiredResultType)
{
    int         parameterCount = list_length(parameters);
    Oid        *inTypes;
    int         inCount = 0;
    Datum      *allTypes;
    Datum      *paramModes;
    Datum      *paramNames;
    int         outCount = 0;
    int         varCount = 0;
    bool        have_names = false;
    bool        have_defaults = false;
    ListCell   *x;
    int         i;
    ParseState *pstate;

    *variadicArgType = InvalidOid;      /* default result */
    *requiredResultType = InvalidOid;   /* default result */

    inTypes = (Oid *) palloc(parameterCount * sizeof(Oid));
    allTypes = (Datum *) palloc(parameterCount * sizeof(Datum));
    paramModes = (Datum *) palloc(parameterCount * sizeof(Datum));
    paramNames = (Datum *) palloc0(parameterCount * sizeof(Datum));
    *parameterDefaults = NIL;

    /* may need a pstate for parse analysis of default exprs */
    pstate = make_parsestate(NULL);
    pstate->p_sourcetext = queryString;

    /* Scan the list and extract data into work arrays */
    i = 0;
    foreach(x, parameters)
    {
        FunctionParameter *fp = (FunctionParameter *) lfirst(x);
        TypeName   *t = fp->argType;
        bool        isinput = false;
        Oid         toid;
        Type        typtup;
        AclResult   aclresult;

        typtup = LookupTypeName(NULL, t, NULL, false);
        if (typtup)
        {
            if (!((Form_pg_type) GETSTRUCT(typtup))->typisdefined)
            {
                /* 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))));
                /* We don't allow creating aggregates on shell types either */
                else if (is_aggregate)
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                             errmsg("aggregate 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))));
            }
            toid = typeTypeId(typtup);
            ReleaseSysCache(typtup);
        }
        else
        {
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_OBJECT),
                     errmsg("type %s does not exist",
                            TypeNameToString(t))));
            toid = InvalidOid;  /* keep compiler quiet */
        }

        aclresult = pg_type_aclcheck(toid, GetUserId(), ACL_USAGE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error_type(aclresult, toid);

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

        /* handle input parameters */
        if (fp->mode != FUNC_PARAM_OUT && fp->mode != FUNC_PARAM_TABLE)
        {
            /* other input parameters can't follow a VARIADIC parameter */
            if (varCount > 0)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                         errmsg("VARIADIC parameter must be the last input parameter")));
            inTypes[inCount++] = toid;
            isinput = true;
        }

        /* handle output parameters */
        if (fp->mode != FUNC_PARAM_IN && fp->mode != FUNC_PARAM_VARIADIC)
        {
            if (outCount == 0)  /* save first output param's type */
                *requiredResultType = toid;
            outCount++;
        }

        if (fp->mode == FUNC_PARAM_VARIADIC)
        {
            *variadicArgType = toid;
            varCount++;
            /* validate variadic parameter type */
            switch (toid)
            {
                case ANYARRAYOID:
                case ANYOID:
                    /* okay */
                    break;
                default:
                    if (!OidIsValid(get_element_type(toid)))
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                             errmsg("VARIADIC parameter must be an array")));
                    break;
            }
        }

        allTypes[i] = ObjectIdGetDatum(toid);

        paramModes[i] = CharGetDatum(fp->mode);

        if (fp->name && fp->name[0])
        {
            ListCell   *px;

            /*
             * As of Postgres 9.0 we disallow using the same name for two
             * input or two output function parameters.  Depending on the
             * function's language, conflicting input and output names might
             * be bad too, but we leave it to the PL to complain if so.
             */
            foreach(px, parameters)
            {
                FunctionParameter *prevfp = (FunctionParameter *) lfirst(px);

                if (prevfp == fp)
                    break;
                /* pure in doesn't conflict with pure out */
                if ((fp->mode == FUNC_PARAM_IN ||
                     fp->mode == FUNC_PARAM_VARIADIC) &&
                    (prevfp->mode == FUNC_PARAM_OUT ||
                     prevfp->mode == FUNC_PARAM_TABLE))
                    continue;
                if ((prevfp->mode == FUNC_PARAM_IN ||
                     prevfp->mode == FUNC_PARAM_VARIADIC) &&
                    (fp->mode == FUNC_PARAM_OUT ||
                     fp->mode == FUNC_PARAM_TABLE))
                    continue;
                if (prevfp->name && prevfp->name[0] &&
                    strcmp(prevfp->name, fp->name) == 0)
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                          errmsg("parameter name \"%s\" used more than once",
                                 fp->name)));
            }

            paramNames[i] = CStringGetTextDatum(fp->name);
            have_names = true;
        }

        if (fp->defexpr)
        {
            Node       *def;

            if (!isinput)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                   errmsg("only input parameters can have default values")));

            def = transformExpr(pstate, fp->defexpr,
                                EXPR_KIND_FUNCTION_DEFAULT);
            def = coerce_to_specific_type(pstate, def, toid, "DEFAULT");
            assign_expr_collations(pstate, def);

            /*
             * Make sure no variables are referred to (this is probably dead
             * code now that add_missing_from is history).
             */
            if (list_length(pstate->p_rtable) != 0 ||
                contain_var_clause(def))
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
                         errmsg("cannot use table references in parameter default value")));

            /*
             * transformExpr() should have already rejected subqueries,
             * aggregates, and window functions, based on the EXPR_KIND_ for a
             * default expression.
             *
             * It can't return a set either --- but coerce_to_specific_type
             * already checked that for us.
             *
             * Note: the point of these restrictions is to ensure that an
             * expression that, on its face, hasn't got subplans, aggregates,
             * etc cannot suddenly have them after function default arguments
             * are inserted.
             */

            *parameterDefaults = lappend(*parameterDefaults, def);
            have_defaults = true;
        }
        else
        {
            if (isinput && have_defaults)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                         errmsg("input parameters after one with a default value must also have defaults")));
        }

        i++;
    }

    free_parsestate(pstate);

    /* Now construct the proper outputs as needed */
    *parameterTypes = buildoidvector(inTypes, inCount);

    if (outCount > 0 || varCount > 0)
    {
        *allParameterTypes = construct_array(allTypes, parameterCount, OIDOID,
                                             sizeof(Oid), true, 'i');
        *parameterModes = construct_array(paramModes, parameterCount, CHAROID,
                                          1, true, 'c');
        if (outCount > 1)
            *requiredResultType = RECORDOID;
        /* otherwise we set requiredResultType correctly above */
    }
    else
    {
        *allParameterTypes = NULL;
        *parameterModes = NULL;
    }

    if (have_names)
    {
        for (i = 0; i < parameterCount; i++)
        {
            if (paramNames[i] == PointerGetDatum(NULL))
                paramNames[i] = CStringGetTextDatum("");
        }
        *parameterNames = construct_array(paramNames, parameterCount, TEXTOID,
                                          -1, false, 'i');
    }
    else
        *parameterNames = NULL;
}


/*
 * Recognize one of the options that can be passed to both CREATE
 * FUNCTION and ALTER FUNCTION and return it via one of the out
 * parameters. Returns true if the passed option was recognized. If
 * the out parameter we were going to assign to points to non-NULL,
 * raise a duplicate-clause error.  (We don't try to detect duplicate
 * SET parameters though --- if you're redundant, the last one wins.)
 */
static bool
compute_common_attribute(DefElem *defel,
                         DefElem **volatility_item,
                         DefElem **strict_item,
                         DefElem **security_item,
                         DefElem **leakproof_item,
                         List **set_items,
                         DefElem **cost_item,
                         DefElem **rows_item,
                         DefElem **parallel_item)
{
    if (strcmp(defel->defname, "volatility") == 0)
    {
        if (*volatility_item)
            goto duplicate_error;

        *volatility_item = defel;
    }
    else if (strcmp(defel->defname, "strict") == 0)
    {
        if (*strict_item)
            goto duplicate_error;

        *strict_item = defel;
    }
    else if (strcmp(defel->defname, "security") == 0)
    {
        if (*security_item)
            goto duplicate_error;

        *security_item = defel;
    }
    else if (strcmp(defel->defname, "leakproof") == 0)
    {
        if (*leakproof_item)
            goto duplicate_error;

        *leakproof_item = defel;
    }
    else if (strcmp(defel->defname, "set") == 0)
    {
        *set_items = lappend(*set_items, defel->arg);
    }
    else if (strcmp(defel->defname, "cost") == 0)
    {
        if (*cost_item)
            goto duplicate_error;

        *cost_item = defel;
    }
    else if (strcmp(defel->defname, "rows") == 0)
    {
        if (*rows_item)
            goto duplicate_error;

        *rows_item = defel;
    }
    else if (strcmp(defel->defname, "parallel") == 0)
    {
        if (*parallel_item)
            goto duplicate_error;

        *parallel_item = defel;
    }
    else
        return false;

    /* Recognized an option */
    return true;

duplicate_error:
    ereport(ERROR,
            (errcode(ERRCODE_SYNTAX_ERROR),
             errmsg("conflicting or redundant options")));
    return false;               /* keep compiler quiet */
}

static char
interpret_func_volatility(DefElem *defel)
{
    char       *str = strVal(defel->arg);

    if (strcmp(str, "immutable") == 0)
        return PROVOLATILE_IMMUTABLE;
    else if (strcmp(str, "stable") == 0)
        return PROVOLATILE_STABLE;
    else if (strcmp(str, "volatile") == 0)
        return PROVOLATILE_VOLATILE;
    else
    {
        elog(ERROR, "invalid volatility \"%s\"", str);
        return 0;               /* keep compiler quiet */
    }
}

static char
interpret_func_parallel(DefElem *defel)
{
    char       *str = strVal(defel->arg);

    if (strcmp(str, "safe") == 0)
        return PROPARALLEL_SAFE;
    else if (strcmp(str, "unsafe") == 0)
        return PROPARALLEL_UNSAFE;
    else if (strcmp(str, "restricted") == 0)
        return PROPARALLEL_RESTRICTED;
    else
    {
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("parallel option \"%s\" not recognized",
                        str)));
        return PROPARALLEL_UNSAFE;      /* keep compiler quiet */
    }
}

/*
 * Update a proconfig value according to a list of VariableSetStmt items.
 *
 * The input and result may be NULL to signify a null entry.
 */
static ArrayType *
update_proconfig_value(ArrayType *a, List *set_items)
{
    ListCell   *l;

    foreach(l, set_items)
    {
        VariableSetStmt *sstmt = (VariableSetStmt *) lfirst(l);

        Assert(IsA(sstmt, VariableSetStmt));
        if (sstmt->kind == VAR_RESET_ALL)
            a = NULL;
        else
        {
            char       *valuestr = ExtractSetVariableArgs(sstmt);

            if (valuestr)
                a = GUCArrayAdd(a, sstmt->name, valuestr);
            else    /* RESET */
                a = GUCArrayDelete(a, sstmt->name);
        }
    }

    return a;
}


/*
 * Dissect the list of options assembled in gram.y into function
 * attributes.
 */
static void
compute_attributes_sql_style(List *options,
                             List **as,
                             char **language,
                             Node **transform,
                             bool *windowfunc_p,
                             char *volatility_p,
                             bool *strict_p,
                             bool *security_definer,
                             bool *leakproof_p,
                             ArrayType **proconfig,
                             float4 *procost,
                             float4 *prorows,
                             char *parallel_p)
{
    ListCell   *option;
    DefElem    *as_item = NULL;
    DefElem    *language_item = NULL;
    DefElem    *transform_item = NULL;
    DefElem    *windowfunc_item = NULL;
    DefElem    *volatility_item = NULL;
    DefElem    *strict_item = NULL;
    DefElem    *security_item = NULL;
    DefElem    *leakproof_item = NULL;
    List       *set_items = NIL;
    DefElem    *cost_item = NULL;
    DefElem    *rows_item = NULL;
    DefElem    *parallel_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, "transform") == 0)
        {
            if (transform_item)
                ereport(ERROR,
                        (errcode(ERRCODE_SYNTAX_ERROR),
                         errmsg("conflicting or redundant options")));
            transform_item = defel;
        }
        else if (strcmp(defel->defname, "window") == 0)
        {
            if (windowfunc_item)
                ereport(ERROR,
                        (errcode(ERRCODE_SYNTAX_ERROR),
                         errmsg("conflicting or redundant options")));
            windowfunc_item = defel;
        }
        else if (compute_common_attribute(defel,
                                          &volatility_item,
                                          &strict_item,
                                          &security_item,
                                          &leakproof_item,
                                          &set_items,
                                          &cost_item,
                                          &rows_item,
                                          &parallel_item))
        {
            /* recognized common option */
            continue;
        }
        else
            elog(ERROR, "option \"%s\" not recognized",
                 defel->defname);
    }

    /* process required items */
    if (as_item)
        *as = (List *) as_item->arg;
    else
    {
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                 errmsg("no function body specified")));
        *as = NIL;              /* keep compiler quiet */
    }

    if (language_item)
        *language = strVal(language_item->arg);
    else
    {
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                 errmsg("no language specified")));
        *language = NULL;       /* keep compiler quiet */
    }

    /* process optional items */
    if (transform_item)
        *transform = transform_item->arg;
    if (windowfunc_item)
        *windowfunc_p = intVal(windowfunc_item->arg);
    if (volatility_item)
        *volatility_p = interpret_func_volatility(volatility_item);
    if (strict_item)
        *strict_p = intVal(strict_item->arg);
    if (security_item)
        *security_definer = intVal(security_item->arg);
    if (leakproof_item)
        *leakproof_p = intVal(leakproof_item->arg);
    if (set_items)
        *proconfig = update_proconfig_value(NULL, set_items);
    if (cost_item)
    {
        *procost = defGetNumeric(cost_item);
        if (*procost <= 0)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("COST must be positive")));
    }
    if (rows_item)
    {
        *prorows = defGetNumeric(rows_item);
        if (*prorows <= 0)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("ROWS must be positive")));
    }
    if (parallel_item)
        *parallel_p = interpret_func_parallel(parallel_item);
}


/*-------------
 *   Interpret the parameters *parameters and return their contents via
 *   *isStrict_p and *volatility_p.
 *
 *  These parameters supply optional information about a function.
 *  All have defaults if not specified. Parameters:
 *
 *   * 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.
 *------------
 */
static void
compute_attributes_with_style(List *parameters, bool *isStrict_p, char *volatility_p)
{
    ListCell   *pl;

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

        if (pg_strcasecmp(param->defname, "isstrict") == 0)
            *isStrict_p = defGetBoolean(param);
        else if (pg_strcasecmp(param->defname, "iscachable") == 0)
        {
            /* obsolete spelling of isImmutable */
            if (defGetBoolean(param))
                *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,
                    char *funcname, 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.  If link symbol is omitted,
         * substitute procedure name.  We also allow link symbol to be
         * specified as "-", since that was the habit in PG versions before
         * 8.4, and there might be dump files out there that don't translate
         * that back to "omitted".
         */
        *probin_str_p = strVal(linitial(as));
        if (list_length(as) == 1)
            *prosrc_str_p = funcname;
        else
        {
            *prosrc_str_p = strVal(lsecond(as));
            if (strcmp(*prosrc_str_p, "-") == 0)
                *prosrc_str_p = funcname;
        }
    }
    else
    {
        /* Everything else wants the given string in prosrc. */
        *prosrc_str_p = strVal(linitial(as));
        *probin_str_p = NULL;

        if (list_length(as) != 1)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                     errmsg("only one AS item needed for language \"%s\"",
                            languageName)));

        if (languageOid == INTERNALlanguageId)
        {
            /*
             * In PostgreSQL versions before 6.5, the SQL name of the created
             * function could not be different from the internal name, and
             * "prosrc" wasn't used.  So there is code out there that does
             * CREATE FUNCTION xyz AS '' LANGUAGE internal. To preserve some
             * modicum of backwards compatibility, accept an empty "prosrc"
             * value as meaning the supplied SQL function name.
             */
            if (strlen(*prosrc_str_p) == 0)
                *prosrc_str_p = funcname;
        }
    }
}


/*
 * CreateFunction
 *   Execute a CREATE FUNCTION utility statement.
 */
ObjectAddress
CreateFunction(CreateFunctionStmt *stmt, const char *queryString)
{
    char       *probin_str;
    char       *prosrc_str;
    Oid         prorettype;
    bool        returnsSet;
    char       *language;
    Oid         languageOid;
    Oid         languageValidator;
    Node       *transformDefElem = NULL;
    char       *funcname;
    Oid         namespaceId;
    AclResult   aclresult;
    oidvector  *parameterTypes;
    ArrayType  *allParameterTypes;
    ArrayType  *parameterModes;
    ArrayType  *parameterNames;
    List       *parameterDefaults;
    Oid         variadicArgType;
    List       *trftypes_list = NIL;
    ArrayType  *trftypes;
    Oid         requiredResultType;
    bool        isWindowFunc,
                isStrict,
                security,
                isLeakProof;
    char        volatility;
    ArrayType  *proconfig;
    float4      procost;
    float4      prorows;
    HeapTuple   languageTuple;
    Form_pg_language languageStruct;
    List       *as_clause;
    char        parallel;

    /* Convert list of names to a name and namespace */
    namespaceId = QualifiedNameGetCreationNamespace(stmt->funcname,
                                                    &funcname);

    /* Check we have creation rights in target namespace */
    aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(), ACL_CREATE);
    if (aclresult != ACLCHECK_OK)
        aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
                       get_namespace_name(namespaceId));

    /* default attributes */
    isWindowFunc = false;
    isStrict = false;
    security = false;
    isLeakProof = false;
    volatility = PROVOLATILE_VOLATILE;
    proconfig = NULL;
    procost = -1;               /* indicates not set */
    prorows = -1;               /* indicates not set */
    parallel = PROPARALLEL_UNSAFE;

    /* override attributes from explicit list */
    compute_attributes_sql_style(stmt->options,
                                 &as_clause, &language, &transformDefElem,
                                 &isWindowFunc, &volatility,
                                 &isStrict, &security, &isLeakProof,
                                 &proconfig, &procost, &prorows, &parallel);

    /* Look up the language and validate permissions */
    languageTuple = SearchSysCache1(LANGNAME, PointerGetDatum(language));
    if (!HeapTupleIsValid(languageTuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("language \"%s\" does not exist", language),
                 (PLTemplateExists(language) ?
                  errhint("Use CREATE LANGUAGE to load the language into the database.") : 0)));

    languageOid = HeapTupleGetOid(languageTuple);
    languageStruct = (Form_pg_language) GETSTRUCT(languageTuple);

    if (languageStruct->lanpltrusted)
    {
        /* if trusted language, need USAGE privilege */
        AclResult   aclresult;

        aclresult = pg_language_aclcheck(languageOid, GetUserId(), ACL_USAGE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, ACL_KIND_LANGUAGE,
                           NameStr(languageStruct->lanname));
    }
    else
    {
        /* if untrusted language, must be superuser */
        if (!superuser())
            aclcheck_error(ACLCHECK_NO_PRIV, ACL_KIND_LANGUAGE,
                           NameStr(languageStruct->lanname));
    }

    languageValidator = languageStruct->lanvalidator;

    ReleaseSysCache(languageTuple);

    /*
     * Only superuser is allowed to create leakproof functions because
     * leakproof functions can see tuples which have not yet been filtered out
     * by security barrier views or row level security policies.
     */
    if (isLeakProof && !superuser())
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("only superuser can define a leakproof function")));

    if (transformDefElem)
    {
        ListCell   *lc;

        Assert(IsA(transformDefElem, List));

        foreach(lc, (List *) transformDefElem)
        {
            Oid         typeid = typenameTypeId(NULL, lfirst(lc));
            Oid         elt = get_base_element_type(typeid);

            typeid = elt ? elt : typeid;

            get_transform_oid(typeid, languageOid, false);
            trftypes_list = lappend_oid(trftypes_list, typeid);
        }
    }

    /*
     * Convert remaining parameters of CREATE to form wanted by
     * ProcedureCreate.
     */
    interpret_function_parameter_list(stmt->parameters,
                                      languageOid,
                                      false,    /* not an aggregate */
                                      queryString,
                                      &parameterTypes,
                                      &allParameterTypes,
                                      &parameterModes,
                                      &parameterNames,
                                      &parameterDefaults,
                                      &variadicArgType,
                                      &requiredResultType);

    if (stmt->returnType)
    {
        /* explicit RETURNS clause */
        compute_return_type(stmt->returnType, languageOid,
                            &prorettype, &returnsSet);
        if (OidIsValid(requiredResultType) && prorettype != requiredResultType)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                     errmsg("function result type must be %s because of OUT parameters",
                            format_type_be(requiredResultType))));
    }
    else if (OidIsValid(requiredResultType))
    {
        /* default RETURNS clause from OUT parameters */
        prorettype = requiredResultType;
        returnsSet = false;
    }
    else
    {
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                 errmsg("function result type must be specified")));
        /* Alternative possibility: default to RETURNS VOID */
        prorettype = VOIDOID;
        returnsSet = false;
    }

    if (list_length(trftypes_list) > 0)
    {
        ListCell   *lc;
        Datum      *arr;
        int         i;

        arr = palloc(list_length(trftypes_list) * sizeof(Datum));
        i = 0;
        foreach(lc, trftypes_list)
            arr[i++] = ObjectIdGetDatum(lfirst_oid(lc));
        trftypes = construct_array(arr, list_length(trftypes_list),
                                   OIDOID, sizeof(Oid), true, 'i');
    }
    else
    {
        /* store SQL NULL instead of emtpy array */
        trftypes = NULL;
    }

    compute_attributes_with_style(stmt->withClause, &isStrict, &volatility);

    interpret_AS_clause(languageOid, language, funcname, as_clause,
                        &prosrc_str, &probin_str);

    /*
     * Set default values for COST and ROWS depending on other parameters;
     * reject ROWS if it's not returnsSet.  NB: pg_dump knows these default
     * values, keep it in sync if you change them.
     */
    if (procost < 0)
    {
        /* SQL and PL-language functions are assumed more expensive */
        if (languageOid == INTERNALlanguageId ||
            languageOid == ClanguageId)
            procost = 1;
        else
            procost = 100;
    }
    if (prorows < 0)
    {
        if (returnsSet)
            prorows = 1000;
        else
            prorows = 0;        /* dummy value if not returnsSet */
    }
    else if (!returnsSet)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("ROWS is not applicable when function does not return a set")));

    /*
     * And now that we have all the parameters, and know we're permitted to do
     * so, go ahead and create the function.
     */
    return ProcedureCreate(funcname,
                           namespaceId,
                           stmt->replace,
                           returnsSet,
                           prorettype,
                           GetUserId(),
                           languageOid,
                           languageValidator,
                           prosrc_str,  /* converted to text later */
                           probin_str,  /* converted to text later */
                           false,       /* not an aggregate */
                           isWindowFunc,
                           security,
                           isLeakProof,
                           isStrict,
                           volatility,
                           parallel,
                           parameterTypes,
                           PointerGetDatum(allParameterTypes),
                           PointerGetDatum(parameterModes),
                           PointerGetDatum(parameterNames),
                           parameterDefaults,
                           PointerGetDatum(trftypes),
                           PointerGetDatum(proconfig),
                           procost,
                           prorows);
}

/*
 * Guts of function deletion.
 *
 * Note: this is also used for aggregate deletion, since the OIDs of
 * both functions and aggregates point to pg_proc.
 */
void
RemoveFunctionById(Oid funcOid)
{
    Relation    relation;
    HeapTuple   tup;
    bool        isagg;

    /*
     * Delete the pg_proc tuple.
     */
    relation = heap_open(ProcedureRelationId, RowExclusiveLock);

    tup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcOid));
    if (!HeapTupleIsValid(tup)) /* should not happen */
        elog(ERROR, "cache lookup failed for function %u", funcOid);

    isagg = ((Form_pg_proc) GETSTRUCT(tup))->proisagg;

    simple_heap_delete(relation, &tup->t_self);

    ReleaseSysCache(tup);

    heap_close(relation, RowExclusiveLock);

    /*
     * If there's a pg_aggregate tuple, delete that too.
     */
    if (isagg)
    {
        relation = heap_open(AggregateRelationId, RowExclusiveLock);

        tup = SearchSysCache1(AGGFNOID, ObjectIdGetDatum(funcOid));
        if (!HeapTupleIsValid(tup))     /* should not happen */
            elog(ERROR, "cache lookup failed for pg_aggregate tuple for function %u", funcOid);

        simple_heap_delete(relation, &tup->t_self);

        ReleaseSysCache(tup);

        heap_close(relation, RowExclusiveLock);
    }
}

/*
 * Implements the ALTER FUNCTION utility command (except for the
 * RENAME and OWNER clauses, which are handled as part of the generic
 * ALTER framework).
 */
ObjectAddress
AlterFunction(AlterFunctionStmt *stmt)
{
    HeapTuple   tup;
    Oid         funcOid;
    Form_pg_proc procForm;
    Relation    rel;
    ListCell   *l;
    DefElem    *volatility_item = NULL;
    DefElem    *strict_item = NULL;
    DefElem    *security_def_item = NULL;
    DefElem    *leakproof_item = NULL;
    List       *set_items = NIL;
    DefElem    *cost_item = NULL;
    DefElem    *rows_item = NULL;
    DefElem    *parallel_item = NULL;
    ObjectAddress address;

    rel = heap_open(ProcedureRelationId, RowExclusiveLock);

    funcOid = LookupFuncNameTypeNames(stmt->func->funcname,
                                      stmt->func->funcargs,
                                      false);

    tup = SearchSysCacheCopy1(PROCOID, ObjectIdGetDatum(funcOid));
    if (!HeapTupleIsValid(tup)) /* should not happen */
        elog(ERROR, "cache lookup failed for function %u", funcOid);

    procForm = (Form_pg_proc) GETSTRUCT(tup);

    /* Permission check: must own function */
    if (!pg_proc_ownercheck(funcOid, GetUserId()))
        aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_PROC,
                       NameListToString(stmt->func->funcname));

    if (procForm->proisagg)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is an aggregate function",
                        NameListToString(stmt->func->funcname))));

    /* Examine requested actions. */
    foreach(l, stmt->actions)
    {
        DefElem    *defel = (DefElem *) lfirst(l);

        if (compute_common_attribute(defel,
                                     &volatility_item,
                                     &strict_item,
                                     &security_def_item,
                                     &leakproof_item,
                                     &set_items,
                                     &cost_item,
                                     &rows_item,
                                     &parallel_item) == false)
            elog(ERROR, "option \"%s\" not recognized", defel->defname);
    }

    if (volatility_item)
        procForm->provolatile = interpret_func_volatility(volatility_item);
    if (strict_item)
        procForm->proisstrict = intVal(strict_item->arg);
    if (security_def_item)
        procForm->prosecdef = intVal(security_def_item->arg);
    if (leakproof_item)
    {
        procForm->proleakproof = intVal(leakproof_item->arg);
        if (procForm->proleakproof && !superuser())
            ereport(ERROR,
                    (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                  errmsg("only superuser can define a leakproof function")));
    }
    if (cost_item)
    {
        procForm->procost = defGetNumeric(cost_item);
        if (procForm->procost <= 0)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("COST must be positive")));
    }
    if (rows_item)
    {
        procForm->prorows = defGetNumeric(rows_item);
        if (procForm->prorows <= 0)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("ROWS must be positive")));
        if (!procForm->proretset)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("ROWS is not applicable when function does not return a set")));
    }
    if (set_items)
    {
        Datum       datum;
        bool        isnull;
        ArrayType  *a;
        Datum       repl_val[Natts_pg_proc];
        bool        repl_null[Natts_pg_proc];
        bool        repl_repl[Natts_pg_proc];

        /* extract existing proconfig setting */
        datum = SysCacheGetAttr(PROCOID, tup, Anum_pg_proc_proconfig, &isnull);
        a = isnull ? NULL : DatumGetArrayTypeP(datum);

        /* update according to each SET or RESET item, left to right */
        a = update_proconfig_value(a, set_items);

        /* update the tuple */
        memset(repl_repl, false, sizeof(repl_repl));
        repl_repl[Anum_pg_proc_proconfig - 1] = true;

        if (a == NULL)
        {
            repl_val[Anum_pg_proc_proconfig - 1] = (Datum) 0;
            repl_null[Anum_pg_proc_proconfig - 1] = true;
        }
        else
        {
            repl_val[Anum_pg_proc_proconfig - 1] = PointerGetDatum(a);
            repl_null[Anum_pg_proc_proconfig - 1] = false;
        }

        tup = heap_modify_tuple(tup, RelationGetDescr(rel),
                                repl_val, repl_null, repl_repl);
    }
    if (parallel_item)
        procForm->proparallel = interpret_func_parallel(parallel_item);

    /* Do the update */
    simple_heap_update(rel, &tup->t_self, tup);
    CatalogUpdateIndexes(rel, tup);

    InvokeObjectPostAlterHook(ProcedureRelationId, funcOid, 0);

    ObjectAddressSet(address, ProcedureRelationId, funcOid);

    heap_close(rel, NoLock);
    heap_freetuple(tup);

    return address;
}

/*
 * SetFunctionReturnType - change declared return type of a function
 *
 * This is presently only used for adjusting legacy functions that return
 * OPAQUE to return whatever we find their correct definition should be.
 * The caller should emit a suitable warning explaining what we did.
 */
void
SetFunctionReturnType(Oid funcOid, Oid newRetType)
{
    Relation    pg_proc_rel;
    HeapTuple   tup;
    Form_pg_proc procForm;

    pg_proc_rel = heap_open(ProcedureRelationId, RowExclusiveLock);

    tup = SearchSysCacheCopy1(PROCOID, ObjectIdGetDatum(funcOid));
    if (!HeapTupleIsValid(tup)) /* should not happen */
        elog(ERROR, "cache lookup failed for function %u", funcOid);
    procForm = (Form_pg_proc) GETSTRUCT(tup);

    if (procForm->prorettype != OPAQUEOID)      /* caller messed up */
        elog(ERROR, "function %u doesn't return OPAQUE", funcOid);

    /* okay to overwrite copied tuple */
    procForm->prorettype = newRetType;

    /* update the catalog and its indexes */
    simple_heap_update(pg_proc_rel, &tup->t_self, tup);

    CatalogUpdateIndexes(pg_proc_rel, tup);

    heap_close(pg_proc_rel, RowExclusiveLock);
}


/*
 * SetFunctionArgType - change declared argument type of a function
 *
 * As above, but change an argument's type.
 */
void
SetFunctionArgType(Oid funcOid, int argIndex, Oid newArgType)
{
    Relation    pg_proc_rel;
    HeapTuple   tup;
    Form_pg_proc procForm;

    pg_proc_rel = heap_open(ProcedureRelationId, RowExclusiveLock);

    tup = SearchSysCacheCopy1(PROCOID, ObjectIdGetDatum(funcOid));
    if (!HeapTupleIsValid(tup)) /* should not happen */
        elog(ERROR, "cache lookup failed for function %u", funcOid);
    procForm = (Form_pg_proc) GETSTRUCT(tup);

    if (argIndex < 0 || argIndex >= procForm->pronargs ||
        procForm->proargtypes.values[argIndex] != OPAQUEOID)
        elog(ERROR, "function %u doesn't take OPAQUE", funcOid);

    /* okay to overwrite copied tuple */
    procForm->proargtypes.values[argIndex] = newArgType;

    /* update the catalog and its indexes */
    simple_heap_update(pg_proc_rel, &tup->t_self, tup);

    CatalogUpdateIndexes(pg_proc_rel, tup);

    heap_close(pg_proc_rel, RowExclusiveLock);
}



/*
 * CREATE CAST
 */
ObjectAddress
CreateCast(CreateCastStmt *stmt)
{
    Oid         sourcetypeid;
    Oid         targettypeid;
    char        sourcetyptype;
    char        targettyptype;
    Oid         funcid;
    Oid         castid;
    int         nargs;
    char        castcontext;
    char        castmethod;
    Relation    relation;
    HeapTuple   tuple;
    Datum       values[Natts_pg_cast];
    bool        nulls[Natts_pg_cast];
    ObjectAddress myself,
                referenced;
    AclResult   aclresult;

    sourcetypeid = typenameTypeId(NULL, stmt->sourcetype);
    targettypeid = typenameTypeId(NULL, stmt->targettype);
    sourcetyptype = get_typtype(sourcetypeid);
    targettyptype = get_typtype(targettypeid);

    /* No pseudo-types allowed */
    if (sourcetyptype == TYPTYPE_PSEUDO)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("source data type %s is a pseudo-type",
                        TypeNameToString(stmt->sourcetype))));

    if (targettyptype == TYPTYPE_PSEUDO)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("target data type %s is a pseudo-type",
                        TypeNameToString(stmt->targettype))));

    /* Permission check */
    if (!pg_type_ownercheck(sourcetypeid, GetUserId())
        && !pg_type_ownercheck(targettypeid, GetUserId()))
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("must be owner of type %s or type %s",
                        format_type_be(sourcetypeid),
                        format_type_be(targettypeid))));

    aclresult = pg_type_aclcheck(sourcetypeid, GetUserId(), ACL_USAGE);
    if (aclresult != ACLCHECK_OK)
        aclcheck_error_type(aclresult, sourcetypeid);

    aclresult = pg_type_aclcheck(targettypeid, GetUserId(), ACL_USAGE);
    if (aclresult != ACLCHECK_OK)
        aclcheck_error_type(aclresult, targettypeid);

    /* Domains are allowed for historical reasons, but we warn */
    if (sourcetyptype == TYPTYPE_DOMAIN)
        ereport(WARNING,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cast will be ignored because the source data type is a domain")));

    else if (targettyptype == TYPTYPE_DOMAIN)
        ereport(WARNING,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("cast will be ignored because the target data type is a domain")));

    /* Detemine the cast method */
    if (stmt->func != NULL)
        castmethod = COERCION_METHOD_FUNCTION;
    else if (stmt->inout)
        castmethod = COERCION_METHOD_INOUT;
    else
        castmethod = COERCION_METHOD_BINARY;

    if (castmethod == COERCION_METHOD_FUNCTION)
    {
        Form_pg_proc procstruct;

        funcid = LookupFuncNameTypeNames(stmt->func->funcname,
                                         stmt->func->funcargs,
                                         false);

        tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
        if (!HeapTupleIsValid(tuple))
            elog(ERROR, "cache lookup failed for function %u", funcid);

        procstruct = (Form_pg_proc) GETSTRUCT(tuple);
        nargs = procstruct->pronargs;
        if (nargs < 1 || nargs > 3)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                  errmsg("cast function must take one to three arguments")));
        if (!IsBinaryCoercible(sourcetypeid, procstruct->proargtypes.values[0]))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("argument of cast function must match or be binary-coercible from source data type")));
        if (nargs > 1 && procstruct->proargtypes.values[1] != INT4OID)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
            errmsg("second argument of cast function must be type integer")));
        if (nargs > 2 && procstruct->proargtypes.values[2] != BOOLOID)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
            errmsg("third argument of cast function must be type boolean")));
        if (!IsBinaryCoercible(procstruct->prorettype, targettypeid))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("return data type of cast function must match or be binary-coercible to target data type")));

        /*
         * Restricting the volatility of a cast function may or may not be a
         * good idea in the abstract, but it definitely breaks many old
         * user-defined types.  Disable this check --- tgl 2/1/03
         */
#ifdef NOT_USED
        if (procstruct->provolatile == PROVOLATILE_VOLATILE)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("cast function must not be volatile")));
#endif
        if (procstruct->proisagg)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("cast function must not be an aggregate function")));
        if (procstruct->proiswindow)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("cast function must not be a window function")));
        if (procstruct->proretset)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("cast function must not return a set")));

        ReleaseSysCache(tuple);
    }
    else
    {
        funcid = InvalidOid;
        nargs = 0;
    }

    if (castmethod == COERCION_METHOD_BINARY)
    {
        int16       typ1len;
        int16       typ2len;
        bool        typ1byval;
        bool        typ2byval;
        char        typ1align;
        char        typ2align;

        /*
         * Must be superuser to create binary-compatible casts, since
         * erroneous casts can easily crash the backend.
         */
        if (!superuser())
            ereport(ERROR,
                    (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
             errmsg("must be superuser to create a cast WITHOUT FUNCTION")));

        /*
         * Also, insist that the types match as to size, alignment, and
         * pass-by-value attributes; this provides at least a crude check that
         * they have similar representations.  A pair of types that fail this
         * test should certainly not be equated.
         */
        get_typlenbyvalalign(sourcetypeid, &typ1len, &typ1byval, &typ1align);
        get_typlenbyvalalign(targettypeid, &typ2len, &typ2byval, &typ2align);
        if (typ1len != typ2len ||
            typ1byval != typ2byval ||
            typ1align != typ2align)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("source and target data types are not physically compatible")));

        /*
         * We know that composite, enum and array types are never binary-
         * compatible with each other.  They all have OIDs embedded in them.
         *
         * Theoretically you could build a user-defined base type that is
         * binary-compatible with a composite, enum, or array type.  But we
         * disallow that too, as in practice such a cast is surely a mistake.
         * You can always work around that by writing a cast function.
         */
        if (sourcetyptype == TYPTYPE_COMPOSITE ||
            targettyptype == TYPTYPE_COMPOSITE)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                  errmsg("composite data types are not binary-compatible")));

        if (sourcetyptype == TYPTYPE_ENUM ||
            targettyptype == TYPTYPE_ENUM)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("enum data types are not binary-compatible")));

        if (OidIsValid(get_element_type(sourcetypeid)) ||
            OidIsValid(get_element_type(targettypeid)))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("array data types are not binary-compatible")));

        /*
         * We also disallow creating binary-compatibility casts involving
         * domains.  Casting from a domain to its base type is already
         * allowed, and casting the other way ought to go through domain
         * coercion to permit constraint checking.  Again, if you're intent on
         * having your own semantics for that, create a no-op cast function.
         *
         * NOTE: if we were to relax this, the above checks for composites
         * etc. would have to be modified to look through domains to their
         * base types.
         */
        if (sourcetyptype == TYPTYPE_DOMAIN ||
            targettyptype == TYPTYPE_DOMAIN)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("domain data types must not be marked binary-compatible")));
    }

    /*
     * Allow source and target types to be same only for length coercion
     * functions.  We assume a multi-arg function does length coercion.
     */
    if (sourcetypeid == targettypeid && nargs < 2)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
              errmsg("source data type and target data type are the same")));

    /* convert CoercionContext enum to char value for castcontext */
    switch (stmt->context)
    {
        case COERCION_IMPLICIT:
            castcontext = COERCION_CODE_IMPLICIT;
            break;
        case COERCION_ASSIGNMENT:
            castcontext = COERCION_CODE_ASSIGNMENT;
            break;
        case COERCION_EXPLICIT:
            castcontext = COERCION_CODE_EXPLICIT;
            break;
        default:
            elog(ERROR, "unrecognized CoercionContext: %d", stmt->context);
            castcontext = 0;    /* keep compiler quiet */
            break;
    }

    relation = heap_open(CastRelationId, RowExclusiveLock);

    /*
     * Check for duplicate.  This is just to give a friendly error message,
     * the unique index would catch it anyway (so no need to sweat about race
     * conditions).
     */
    tuple = SearchSysCache2(CASTSOURCETARGET,
                            ObjectIdGetDatum(sourcetypeid),
                            ObjectIdGetDatum(targettypeid));
    if (HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_DUPLICATE_OBJECT),
                 errmsg("cast from type %s to type %s already exists",
                        format_type_be(sourcetypeid),
                        format_type_be(targettypeid))));

    /* ready to go */
    values[Anum_pg_cast_castsource - 1] = ObjectIdGetDatum(sourcetypeid);
    values[Anum_pg_cast_casttarget - 1] = ObjectIdGetDatum(targettypeid);
    values[Anum_pg_cast_castfunc - 1] = ObjectIdGetDatum(funcid);
    values[Anum_pg_cast_castcontext - 1] = CharGetDatum(castcontext);
    values[Anum_pg_cast_castmethod - 1] = CharGetDatum(castmethod);

    MemSet(nulls, false, sizeof(nulls));

    tuple = heap_form_tuple(RelationGetDescr(relation), values, nulls);

    castid = simple_heap_insert(relation, tuple);

    CatalogUpdateIndexes(relation, tuple);

    /* make dependency entries */
    myself.classId = CastRelationId;
    myself.objectId = castid;
    myself.objectSubId = 0;

    /* dependency on source type */
    referenced.classId = TypeRelationId;
    referenced.objectId = sourcetypeid;
    referenced.objectSubId = 0;
    recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);

    /* dependency on target type */
    referenced.classId = TypeRelationId;
    referenced.objectId = targettypeid;
    referenced.objectSubId = 0;
    recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);

    /* dependency on function */
    if (OidIsValid(funcid))
    {
        referenced.classId = ProcedureRelationId;
        referenced.objectId = funcid;
        referenced.objectSubId = 0;
        recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    }

    /* dependency on extension */
    recordDependencyOnCurrentExtension(&myself, false);

    /* Post creation hook for new cast */
    InvokeObjectPostCreateHook(CastRelationId, castid, 0);

    heap_freetuple(tuple);

    heap_close(relation, RowExclusiveLock);

    return myself;
}

/*
 * get_cast_oid - given two type OIDs, look up a cast OID
 *
 * If missing_ok is false, throw an error if the cast is not found.  If
 * true, just return InvalidOid.
 */
Oid
get_cast_oid(Oid sourcetypeid, Oid targettypeid, bool missing_ok)
{
    Oid         oid;

    oid = GetSysCacheOid2(CASTSOURCETARGET,
                          ObjectIdGetDatum(sourcetypeid),
                          ObjectIdGetDatum(targettypeid));
    if (!OidIsValid(oid) && !missing_ok)
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("cast from type %s to type %s does not exist",
                        format_type_be(sourcetypeid),
                        format_type_be(targettypeid))));
    return oid;
}

void
DropCastById(Oid castOid)
{
    Relation    relation;
    ScanKeyData scankey;
    SysScanDesc scan;
    HeapTuple   tuple;

    relation = heap_open(CastRelationId, RowExclusiveLock);

    ScanKeyInit(&scankey,
                ObjectIdAttributeNumber,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(castOid));
    scan = systable_beginscan(relation, CastOidIndexId, true,
                              NULL, 1, &scankey);

    tuple = systable_getnext(scan);
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "could not find tuple for cast %u", castOid);
    simple_heap_delete(relation, &tuple->t_self);

    systable_endscan(scan);
    heap_close(relation, RowExclusiveLock);
}


static void
check_transform_function(Form_pg_proc procstruct)
{
    if (procstruct->provolatile == PROVOLATILE_VOLATILE)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("transform function must not be volatile")));
    if (procstruct->proisagg)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
            errmsg("transform function must not be an aggregate function")));
    if (procstruct->proiswindow)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("transform function must not be a window function")));
    if (procstruct->proretset)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("transform function must not return a set")));
    if (procstruct->pronargs != 1)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("transform function must take one argument")));
    if (procstruct->proargtypes.values[0] != INTERNALOID)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("first argument of transform function must be type \"internal\"")));
}


/*
 * CREATE TRANSFORM
 */
ObjectAddress
CreateTransform(CreateTransformStmt *stmt)
{
    Oid         typeid;
    char        typtype;
    Oid         langid;
    Oid         fromsqlfuncid;
    Oid         tosqlfuncid;
    AclResult   aclresult;
    Form_pg_proc procstruct;
    Datum       values[Natts_pg_transform];
    bool        nulls[Natts_pg_transform];
    bool        replaces[Natts_pg_transform];
    Oid         transformid;
    HeapTuple   tuple;
    HeapTuple   newtuple;
    Relation    relation;
    ObjectAddress myself,
                referenced;
    bool        is_replace;

    /*
     * Get the type
     */
    typeid = typenameTypeId(NULL, stmt->type_name);
    typtype = get_typtype(typeid);

    if (typtype == TYPTYPE_PSEUDO)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("data type %s is a pseudo-type",
                        TypeNameToString(stmt->type_name))));

    if (typtype == TYPTYPE_DOMAIN)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("data type %s is a domain",
                        TypeNameToString(stmt->type_name))));

    if (!pg_type_ownercheck(typeid, GetUserId()))
        aclcheck_error_type(ACLCHECK_NOT_OWNER, typeid);

    aclresult = pg_type_aclcheck(typeid, GetUserId(), ACL_USAGE);
    if (aclresult != ACLCHECK_OK)
        aclcheck_error_type(aclresult, typeid);

    /*
     * Get the language
     */
    langid = get_language_oid(stmt->lang, false);

    aclresult = pg_language_aclcheck(langid, GetUserId(), ACL_USAGE);
    if (aclresult != ACLCHECK_OK)
        aclcheck_error(aclresult, ACL_KIND_LANGUAGE, stmt->lang);

    /*
     * Get the functions
     */
    if (stmt->fromsql)
    {
        fromsqlfuncid = LookupFuncNameTypeNames(stmt->fromsql->funcname, stmt->fromsql->funcargs, false);

        if (!pg_proc_ownercheck(fromsqlfuncid, GetUserId()))
            aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_PROC, NameListToString(stmt->fromsql->funcname));

        aclresult = pg_proc_aclcheck(fromsqlfuncid, GetUserId(), ACL_EXECUTE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, ACL_KIND_PROC, NameListToString(stmt->fromsql->funcname));

        tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(fromsqlfuncid));
        if (!HeapTupleIsValid(tuple))
            elog(ERROR, "cache lookup failed for function %u", fromsqlfuncid);
        procstruct = (Form_pg_proc) GETSTRUCT(tuple);
        if (procstruct->prorettype != INTERNALOID)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("return data type of FROM SQL function must be \"internal\"")));
        check_transform_function(procstruct);
        ReleaseSysCache(tuple);
    }
    else
        fromsqlfuncid = InvalidOid;

    if (stmt->tosql)
    {
        tosqlfuncid = LookupFuncNameTypeNames(stmt->tosql->funcname, stmt->tosql->funcargs, false);

        if (!pg_proc_ownercheck(tosqlfuncid, GetUserId()))
            aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_PROC, NameListToString(stmt->tosql->funcname));

        aclresult = pg_proc_aclcheck(tosqlfuncid, GetUserId(), ACL_EXECUTE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, ACL_KIND_PROC, NameListToString(stmt->tosql->funcname));

        tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(tosqlfuncid));
        if (!HeapTupleIsValid(tuple))
            elog(ERROR, "cache lookup failed for function %u", tosqlfuncid);
        procstruct = (Form_pg_proc) GETSTRUCT(tuple);
        if (procstruct->prorettype != typeid)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("return data type of TO SQL function must be the transform data type")));
        check_transform_function(procstruct);
        ReleaseSysCache(tuple);
    }
    else
        tosqlfuncid = InvalidOid;

    /*
     * Ready to go
     */
    values[Anum_pg_transform_trftype - 1] = ObjectIdGetDatum(typeid);
    values[Anum_pg_transform_trflang - 1] = ObjectIdGetDatum(langid);
    values[Anum_pg_transform_trffromsql - 1] = ObjectIdGetDatum(fromsqlfuncid);
    values[Anum_pg_transform_trftosql - 1] = ObjectIdGetDatum(tosqlfuncid);

    MemSet(nulls, false, sizeof(nulls));

    relation = heap_open(TransformRelationId, RowExclusiveLock);

    tuple = SearchSysCache2(TRFTYPELANG,
                            ObjectIdGetDatum(typeid),
                            ObjectIdGetDatum(langid));
    if (HeapTupleIsValid(tuple))
    {
        if (!stmt->replace)
            ereport(ERROR,
                    (errcode(ERRCODE_DUPLICATE_OBJECT),
               errmsg("transform for type %s language \"%s\" already exists",
                      format_type_be(typeid),
                      stmt->lang)));

        MemSet(replaces, false, sizeof(replaces));
        replaces[Anum_pg_transform_trffromsql - 1] = true;
        replaces[Anum_pg_transform_trftosql - 1] = true;

        newtuple = heap_modify_tuple(tuple, RelationGetDescr(relation), values, nulls, replaces);
        simple_heap_update(relation, &newtuple->t_self, newtuple);

        transformid = HeapTupleGetOid(tuple);
        ReleaseSysCache(tuple);
        is_replace = true;
    }
    else
    {
        newtuple = heap_form_tuple(RelationGetDescr(relation), values, nulls);
        transformid = simple_heap_insert(relation, newtuple);
        is_replace = false;
    }

    CatalogUpdateIndexes(relation, newtuple);

    if (is_replace)
        deleteDependencyRecordsFor(TransformRelationId, transformid, true);

    /* make dependency entries */
    myself.classId = TransformRelationId;
    myself.objectId = transformid;
    myself.objectSubId = 0;

    /* dependency on language */
    referenced.classId = LanguageRelationId;
    referenced.objectId = langid;
    referenced.objectSubId = 0;
    recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);

    /* dependency on type */
    referenced.classId = TypeRelationId;
    referenced.objectId = typeid;
    referenced.objectSubId = 0;
    recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);

    /* dependencies on functions */
    if (OidIsValid(fromsqlfuncid))
    {
        referenced.classId = ProcedureRelationId;
        referenced.objectId = fromsqlfuncid;
        referenced.objectSubId = 0;
        recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    }
    if (OidIsValid(tosqlfuncid))
    {
        referenced.classId = ProcedureRelationId;
        referenced.objectId = tosqlfuncid;
        referenced.objectSubId = 0;
        recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    }

    /* dependency on extension */
    recordDependencyOnCurrentExtension(&myself, is_replace);

    /* Post creation hook for new transform */
    InvokeObjectPostCreateHook(TransformRelationId, transformid, 0);

    heap_freetuple(newtuple);

    heap_close(relation, RowExclusiveLock);

    return myself;
}


/*
 * get_transform_oid - given type OID and language OID, look up a transform OID
 *
 * If missing_ok is false, throw an error if the transform is not found.  If
 * true, just return InvalidOid.
 */
Oid
get_transform_oid(Oid type_id, Oid lang_id, bool missing_ok)
{
    Oid         oid;

    oid = GetSysCacheOid2(TRFTYPELANG,
                          ObjectIdGetDatum(type_id),
                          ObjectIdGetDatum(lang_id));
    if (!OidIsValid(oid) && !missing_ok)
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
               errmsg("transform for type %s language \"%s\" does not exist",
                      format_type_be(type_id),
                      get_language_name(lang_id, false))));
    return oid;
}


void
DropTransformById(Oid transformOid)
{
    Relation    relation;
    ScanKeyData scankey;
    SysScanDesc scan;
    HeapTuple   tuple;

    relation = heap_open(TransformRelationId, RowExclusiveLock);

    ScanKeyInit(&scankey,
                ObjectIdAttributeNumber,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(transformOid));
    scan = systable_beginscan(relation, TransformOidIndexId, true,
                              NULL, 1, &scankey);

    tuple = systable_getnext(scan);
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "could not find tuple for transform %u", transformOid);
    simple_heap_delete(relation, &tuple->t_self);

    systable_endscan(scan);
    heap_close(relation, RowExclusiveLock);
}


/*
 * Subroutine for ALTER FUNCTION/AGGREGATE SET SCHEMA/RENAME
 *
 * Is there a function with the given name and signature already in the given
 * namespace?  If so, raise an appropriate error message.
 */
void
IsThereFunctionInNamespace(const char *proname, int pronargs,
                           oidvector *proargtypes, Oid nspOid)
{
    /* check for duplicate name (more friendly than unique-index failure) */
    if (SearchSysCacheExists3(PROCNAMEARGSNSP,
                              CStringGetDatum(proname),
                              PointerGetDatum(proargtypes),
                              ObjectIdGetDatum(nspOid)))
        ereport(ERROR,
                (errcode(ERRCODE_DUPLICATE_FUNCTION),
                 errmsg("function %s already exists in schema \"%s\"",
                        funcname_signature_string(proname, pronargs,
                                                  NIL, proargtypes->values),
                        get_namespace_name(nspOid))));
}

/*
 * ExecuteDoStmt
 *      Execute inline procedural-language code
 */
void
ExecuteDoStmt(DoStmt *stmt)
{
    InlineCodeBlock *codeblock = makeNode(InlineCodeBlock);
    ListCell   *arg;
    DefElem    *as_item = NULL;
    DefElem    *language_item = NULL;
    char       *language;
    Oid         laninline;
    HeapTuple   languageTuple;
    Form_pg_language languageStruct;

    /* Process options we got from gram.y */
    foreach(arg, stmt->args)
    {
        DefElem    *defel = (DefElem *) lfirst(arg);

        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
            elog(ERROR, "option \"%s\" not recognized",
                 defel->defname);
    }

    if (as_item)
        codeblock->source_text = strVal(as_item->arg);
    else
        ereport(ERROR,
                (errcode(ERRCODE_SYNTAX_ERROR),
                 errmsg("no inline code specified")));

    /* if LANGUAGE option wasn't specified, use the default */
    if (language_item)
        language = strVal(language_item->arg);
    else
        language = "plpgsql";

    /* Look up the language and validate permissions */
    languageTuple = SearchSysCache1(LANGNAME, PointerGetDatum(language));
    if (!HeapTupleIsValid(languageTuple))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("language \"%s\" does not exist", language),
                 (PLTemplateExists(language) ?
                  errhint("Use CREATE LANGUAGE to load the language into the database.") : 0)));

    codeblock->langOid = HeapTupleGetOid(languageTuple);
    languageStruct = (Form_pg_language) GETSTRUCT(languageTuple);
    codeblock->langIsTrusted = languageStruct->lanpltrusted;

    if (languageStruct->lanpltrusted)
    {
        /* if trusted language, need USAGE privilege */
        AclResult   aclresult;

        aclresult = pg_language_aclcheck(codeblock->langOid, GetUserId(),
                                         ACL_USAGE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, ACL_KIND_LANGUAGE,
                           NameStr(languageStruct->lanname));
    }
    else
    {
        /* if untrusted language, must be superuser */
        if (!superuser())
            aclcheck_error(ACLCHECK_NO_PRIV, ACL_KIND_LANGUAGE,
                           NameStr(languageStruct->lanname));
    }

    /* get the handler function's OID */
    laninline = languageStruct->laninline;
    if (!OidIsValid(laninline))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("language \"%s\" does not support inline code execution",
                    NameStr(languageStruct->lanname))));

    ReleaseSysCache(languageTuple);

    /* execute the inline handler */
    OidFunctionCall1(laninline, PointerGetDatum(codeblock));
}