proclang.c

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/*-------------------------------------------------------------------------
 *
 * proclang.c
 *    PostgreSQL LANGUAGE support code.
 *
 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/backend/commands/proclang.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "access/table.h"
#include "catalog/catalog.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/objectaccess.h"
#include "catalog/pg_language.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "commands/proclang.h"
#include "miscadmin.h"
#include "parser/parse_func.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/syscache.h"
 
 
/*
 * CREATE LANGUAGE
 */
ObjectAddress
CreateProceduralLanguage(CreatePLangStmt *stmt)
{
    const char *languageName = stmt->plname;
    Oid         languageOwner = GetUserId();
    Oid         handlerOid,
                inlineOid,
                valOid;
    Oid         funcrettype;
    Oid         funcargtypes[1];
    Relation    rel;
    TupleDesc   tupDesc;
    Datum       values[Natts_pg_language];
    bool        nulls[Natts_pg_language];
    bool        replaces[Natts_pg_language];
    NameData    langname;
    HeapTuple   oldtup;
    HeapTuple   tup;
    Oid         langoid;
    bool        is_update;
    ObjectAddress myself,
                referenced;
    ObjectAddresses *addrs;
 
    /*
     * Check permission
     */
    if (!superuser())
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("must be superuser to create custom procedural language")));
 
    /*
     * Lookup the PL handler function and check that it is of the expected
     * return type
     */
    Assert(stmt->plhandler);
    handlerOid = LookupFuncName(stmt->plhandler, 0, NULL, false);
    funcrettype = get_func_rettype(handlerOid);
    if (funcrettype != LANGUAGE_HANDLEROID)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("function %s must return type %s",
                        NameListToString(stmt->plhandler), "language_handler")));
 
    /* validate the inline function */
    if (stmt->plinline)
    {
        funcargtypes[0] = INTERNALOID;
        inlineOid = LookupFuncName(stmt->plinline, 1, funcargtypes, false);
        /* return value is ignored, so we don't check the type */
    }
    else
        inlineOid = InvalidOid;
 
    /* validate the validator function */
    if (stmt->plvalidator)
    {
        funcargtypes[0] = OIDOID;
        valOid = LookupFuncName(stmt->plvalidator, 1, funcargtypes, false);
        /* return value is ignored, so we don't check the type */
    }
    else
        valOid = InvalidOid;
 
    /* ok to create it */
    rel = table_open(LanguageRelationId, RowExclusiveLock);
    tupDesc = RelationGetDescr(rel);
 
    /* Prepare data to be inserted */
    memset(values, 0, sizeof(values));
    memset(nulls, false, sizeof(nulls));
    memset(replaces, true, sizeof(replaces));
 
    namestrcpy(&langname, languageName);
    values[Anum_pg_language_lanname - 1] = NameGetDatum(&langname);
    values[Anum_pg_language_lanowner - 1] = ObjectIdGetDatum(languageOwner);
    values[Anum_pg_language_lanispl - 1] = BoolGetDatum(true);
    values[Anum_pg_language_lanpltrusted - 1] = BoolGetDatum(stmt->pltrusted);
    values[Anum_pg_language_lanplcallfoid - 1] = ObjectIdGetDatum(handlerOid);
    values[Anum_pg_language_laninline - 1] = ObjectIdGetDatum(inlineOid);
    values[Anum_pg_language_lanvalidator - 1] = ObjectIdGetDatum(valOid);
    nulls[Anum_pg_language_lanacl - 1] = true;
 
    /* Check for pre-existing definition */
    oldtup = SearchSysCache1(LANGNAME, PointerGetDatum(languageName));
 
    if (HeapTupleIsValid(oldtup))
    {
        Form_pg_language oldform = (Form_pg_language) GETSTRUCT(oldtup);
 
        /* There is one; okay to replace it? */
        if (!stmt->replace)
            ereport(ERROR,
                    (errcode(ERRCODE_DUPLICATE_OBJECT),
                     errmsg("language \"%s\" already exists", languageName)));
 
        /* This is currently pointless, since we already checked superuser */
#ifdef NOT_USED
        if (!object_ownercheck(LanguageRelationId, oldform->oid, languageOwner))
            aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_LANGUAGE,
                           languageName);
#endif
 
        /*
         * Do not change existing oid, ownership or permissions.  Note
         * dependency-update code below has to agree with this decision.
         */
        replaces[Anum_pg_language_oid - 1] = false;
        replaces[Anum_pg_language_lanowner - 1] = false;
        replaces[Anum_pg_language_lanacl - 1] = false;
 
        /* Okay, do it... */
        tup = heap_modify_tuple(oldtup, tupDesc, values, nulls, replaces);
        CatalogTupleUpdate(rel, &tup->t_self, tup);
 
        langoid = oldform->oid;
        ReleaseSysCache(oldtup);
        is_update = true;
    }
    else
    {
        /* Creating a new language */
        langoid = GetNewOidWithIndex(rel, LanguageOidIndexId,
                                     Anum_pg_language_oid);
        values[Anum_pg_language_oid - 1] = ObjectIdGetDatum(langoid);
        tup = heap_form_tuple(tupDesc, values, nulls);
        CatalogTupleInsert(rel, tup);
        is_update = false;
    }
 
    /*
     * Create dependencies for the new language.  If we are updating an
     * existing language, first delete any existing pg_depend entries.
     * (However, since we are not changing ownership or permissions, the
     * shared dependencies do *not* need to change, and we leave them alone.)
     */
    myself.classId = LanguageRelationId;
    myself.objectId = langoid;
    myself.objectSubId = 0;
 
    if (is_update)
        deleteDependencyRecordsFor(myself.classId, myself.objectId, true);
 
    /* dependency on owner of language */
    if (!is_update)
        recordDependencyOnOwner(myself.classId, myself.objectId,
                                languageOwner);
 
    /* dependency on extension */
    recordDependencyOnCurrentExtension(&myself, is_update);
 
    addrs = new_object_addresses();
 
    /* dependency on the PL handler function */
    ObjectAddressSet(referenced, ProcedureRelationId, handlerOid);
    add_exact_object_address(&referenced, addrs);
 
    /* dependency on the inline handler function, if any */
    if (OidIsValid(inlineOid))
    {
        ObjectAddressSet(referenced, ProcedureRelationId, inlineOid);
        add_exact_object_address(&referenced, addrs);
    }
 
    /* dependency on the validator function, if any */
    if (OidIsValid(valOid))
    {
        ObjectAddressSet(referenced, ProcedureRelationId, valOid);
        add_exact_object_address(&referenced, addrs);
    }
 
    record_object_address_dependencies(&myself, addrs, DEPENDENCY_NORMAL);
    free_object_addresses(addrs);
 
    /* Post creation hook for new procedural language */
    InvokeObjectPostCreateHook(LanguageRelationId, myself.objectId, 0);
 
    table_close(rel, RowExclusiveLock);
 
    return myself;
}
 
/*
 * get_language_oid - given a language name, look up the OID
 *
 * If missing_ok is false, throw an error if language name not found.  If
 * true, just return InvalidOid.
 */
Oid
get_language_oid(const char *langname, bool missing_ok)
{
    Oid         oid;
 
    oid = GetSysCacheOid1(LANGNAME, Anum_pg_language_oid,
                          CStringGetDatum(langname));
    if (!OidIsValid(oid) && !missing_ok)
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("language \"%s\" does not exist", langname)));
    return oid;
}