Update copyright for 2022

[pgsql.git] / src / backend / utils / adt / enum.c

/*-------------------------------------------------------------------------
 *
 * enum.c
 *        I/O functions, operators, aggregates etc for enum types
 *
 * Copyright (c) 2006-2022, PostgreSQL Global Development Group
 *
 *
 * IDENTIFICATION
 *        src/backend/utils/adt/enum.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/genam.h"
#include "access/htup_details.h"
#include "access/table.h"
#include "catalog/pg_enum.h"
#include "libpq/pqformat.h"
#include "storage/procarray.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/snapmgr.h"
#include "utils/syscache.h"
#include "utils/typcache.h"


static Oid      enum_endpoint(Oid enumtypoid, ScanDirection direction);
static ArrayType *enum_range_internal(Oid enumtypoid, Oid lower, Oid upper);


/*
 * Disallow use of an uncommitted pg_enum tuple.
 *
 * We need to make sure that uncommitted enum values don't get into indexes.
 * If they did, and if we then rolled back the pg_enum addition, we'd have
 * broken the index because value comparisons will not work reliably without
 * an underlying pg_enum entry.  (Note that removal of the heap entry
 * containing an enum value is not sufficient to ensure that it doesn't appear
 * in upper levels of indexes.)  To do this we prevent an uncommitted row from
 * being used for any SQL-level purpose.  This is stronger than necessary,
 * since the value might not be getting inserted into a table or there might
 * be no index on its column, but it's easy to enforce centrally.
 *
 * However, it's okay to allow use of uncommitted values belonging to enum
 * types that were themselves created in the same transaction, because then
 * any such index would also be new and would go away altogether on rollback.
 * We don't implement that fully right now, but we do allow free use of enum
 * values created during CREATE TYPE AS ENUM, which are surely of the same
 * lifespan as the enum type.  (This case is required by "pg_restore -1".)
 * Values added by ALTER TYPE ADD VALUE are currently restricted, but could
 * be allowed if the enum type could be proven to have been created earlier
 * in the same transaction.  (Note that comparing tuple xmins would not work
 * for that, because the type tuple might have been updated in the current
 * transaction.  Subtransactions also create hazards to be accounted for.)
 *
 * This function needs to be called (directly or indirectly) in any of the
 * functions below that could return an enum value to SQL operations.
 */
static void
check_safe_enum_use(HeapTuple enumval_tup)
{
        TransactionId xmin;
        Form_pg_enum en = (Form_pg_enum) GETSTRUCT(enumval_tup);

        /*
         * If the row is hinted as committed, it's surely safe.  This provides a
         * fast path for all normal use-cases.
         */
        if (HeapTupleHeaderXminCommitted(enumval_tup->t_data))
                return;

        /*
         * Usually, a row would get hinted as committed when it's read or loaded
         * into syscache; but just in case not, let's check the xmin directly.
         */
        xmin = HeapTupleHeaderGetXmin(enumval_tup->t_data);
        if (!TransactionIdIsInProgress(xmin) &&
                TransactionIdDidCommit(xmin))
                return;

        /*
         * Check if the enum value is uncommitted.  If not, it's safe, because it
         * was made during CREATE TYPE AS ENUM and can't be shorter-lived than its
         * owning type.  (This'd also be false for values made by other
         * transactions; but the previous tests should have handled all of those.)
         */
        if (!EnumUncommitted(en->oid))
                return;

        /*
         * There might well be other tests we could do here to narrow down the
         * unsafe conditions, but for now just raise an exception.
         */
        ereport(ERROR,
                        (errcode(ERRCODE_UNSAFE_NEW_ENUM_VALUE_USAGE),
                         errmsg("unsafe use of new value \"%s\" of enum type %s",
                                        NameStr(en->enumlabel),
                                        format_type_be(en->enumtypid)),
                         errhint("New enum values must be committed before they can be used.")));
}


/* Basic I/O support */

Datum
enum_in(PG_FUNCTION_ARGS)
{
        char       *name = PG_GETARG_CSTRING(0);
        Oid                     enumtypoid = PG_GETARG_OID(1);
        Oid                     enumoid;
        HeapTuple       tup;

        /* must check length to prevent Assert failure within SearchSysCache */
        if (strlen(name) >= NAMEDATALEN)
                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                                 errmsg("invalid input value for enum %s: \"%s\"",
                                                format_type_be(enumtypoid),
                                                name)));

        tup = SearchSysCache2(ENUMTYPOIDNAME,
                                                  ObjectIdGetDatum(enumtypoid),
                                                  CStringGetDatum(name));
        if (!HeapTupleIsValid(tup))
                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                                 errmsg("invalid input value for enum %s: \"%s\"",
                                                format_type_be(enumtypoid),
                                                name)));

        /* check it's safe to use in SQL */
        check_safe_enum_use(tup);

        /*
         * This comes from pg_enum.oid and stores system oids in user tables. This
         * oid must be preserved by binary upgrades.
         */
        enumoid = ((Form_pg_enum) GETSTRUCT(tup))->oid;

        ReleaseSysCache(tup);

        PG_RETURN_OID(enumoid);
}

Datum
enum_out(PG_FUNCTION_ARGS)
{
        Oid                     enumval = PG_GETARG_OID(0);
        char       *result;
        HeapTuple       tup;
        Form_pg_enum en;

        tup = SearchSysCache1(ENUMOID, ObjectIdGetDatum(enumval));
        if (!HeapTupleIsValid(tup))
                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                                 errmsg("invalid internal value for enum: %u",
                                                enumval)));
        en = (Form_pg_enum) GETSTRUCT(tup);

        result = pstrdup(NameStr(en->enumlabel));

        ReleaseSysCache(tup);

        PG_RETURN_CSTRING(result);
}

/* Binary I/O support */
Datum
enum_recv(PG_FUNCTION_ARGS)
{
        StringInfo      buf = (StringInfo) PG_GETARG_POINTER(0);
        Oid                     enumtypoid = PG_GETARG_OID(1);
        Oid                     enumoid;
        HeapTuple       tup;
        char       *name;
        int                     nbytes;

        name = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);

        /* must check length to prevent Assert failure within SearchSysCache */
        if (strlen(name) >= NAMEDATALEN)
                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                                 errmsg("invalid input value for enum %s: \"%s\"",
                                                format_type_be(enumtypoid),
                                                name)));

        tup = SearchSysCache2(ENUMTYPOIDNAME,
                                                  ObjectIdGetDatum(enumtypoid),
                                                  CStringGetDatum(name));
        if (!HeapTupleIsValid(tup))
                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                                 errmsg("invalid input value for enum %s: \"%s\"",
                                                format_type_be(enumtypoid),
                                                name)));

        /* check it's safe to use in SQL */
        check_safe_enum_use(tup);

        enumoid = ((Form_pg_enum) GETSTRUCT(tup))->oid;

        ReleaseSysCache(tup);

        pfree(name);

        PG_RETURN_OID(enumoid);
}

Datum
enum_send(PG_FUNCTION_ARGS)
{
        Oid                     enumval = PG_GETARG_OID(0);
        StringInfoData buf;
        HeapTuple       tup;
        Form_pg_enum en;

        tup = SearchSysCache1(ENUMOID, ObjectIdGetDatum(enumval));
        if (!HeapTupleIsValid(tup))
                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                                 errmsg("invalid internal value for enum: %u",
                                                enumval)));
        en = (Form_pg_enum) GETSTRUCT(tup);

        pq_begintypsend(&buf);
        pq_sendtext(&buf, NameStr(en->enumlabel), strlen(NameStr(en->enumlabel)));

        ReleaseSysCache(tup);

        PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}

/* Comparison functions and related */

/*
 * enum_cmp_internal is the common engine for all the visible comparison
 * functions, except for enum_eq and enum_ne which can just check for OID
 * equality directly.
 */
static int
enum_cmp_internal(Oid arg1, Oid arg2, FunctionCallInfo fcinfo)
{
        TypeCacheEntry *tcache;

        /*
         * We don't need the typcache except in the hopefully-uncommon case that
         * one or both Oids are odd.  This means that cursory testing of code that
         * fails to pass flinfo to an enum comparison function might not disclose
         * the oversight.  To make such errors more obvious, Assert that we have a
         * place to cache even when we take a fast-path exit.
         */
        Assert(fcinfo->flinfo != NULL);

        /* Equal OIDs are equal no matter what */
        if (arg1 == arg2)
                return 0;

        /* Fast path: even-numbered Oids are known to compare correctly */
        if ((arg1 & 1) == 0 && (arg2 & 1) == 0)
        {
                if (arg1 < arg2)
                        return -1;
                else
                        return 1;
        }

        /* Locate the typcache entry for the enum type */
        tcache = (TypeCacheEntry *) fcinfo->flinfo->fn_extra;
        if (tcache == NULL)
        {
                HeapTuple       enum_tup;
                Form_pg_enum en;
                Oid                     typeoid;

                /* Get the OID of the enum type containing arg1 */
                enum_tup = SearchSysCache1(ENUMOID, ObjectIdGetDatum(arg1));
                if (!HeapTupleIsValid(enum_tup))
                        ereport(ERROR,
                                        (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                                         errmsg("invalid internal value for enum: %u",
                                                        arg1)));
                en = (Form_pg_enum) GETSTRUCT(enum_tup);
                typeoid = en->enumtypid;
                ReleaseSysCache(enum_tup);
                /* Now locate and remember the typcache entry */
                tcache = lookup_type_cache(typeoid, 0);
                fcinfo->flinfo->fn_extra = (void *) tcache;
        }

        /* The remaining comparison logic is in typcache.c */
        return compare_values_of_enum(tcache, arg1, arg2);
}

Datum
enum_lt(PG_FUNCTION_ARGS)
{
        Oid                     a = PG_GETARG_OID(0);
        Oid                     b = PG_GETARG_OID(1);

        PG_RETURN_BOOL(enum_cmp_internal(a, b, fcinfo) < 0);
}

Datum
enum_le(PG_FUNCTION_ARGS)
{
        Oid                     a = PG_GETARG_OID(0);
        Oid                     b = PG_GETARG_OID(1);

        PG_RETURN_BOOL(enum_cmp_internal(a, b, fcinfo) <= 0);
}

Datum
enum_eq(PG_FUNCTION_ARGS)
{
        Oid                     a = PG_GETARG_OID(0);
        Oid                     b = PG_GETARG_OID(1);

        PG_RETURN_BOOL(a == b);
}

Datum
enum_ne(PG_FUNCTION_ARGS)
{
        Oid                     a = PG_GETARG_OID(0);
        Oid                     b = PG_GETARG_OID(1);

        PG_RETURN_BOOL(a != b);
}

Datum
enum_ge(PG_FUNCTION_ARGS)
{
        Oid                     a = PG_GETARG_OID(0);
        Oid                     b = PG_GETARG_OID(1);

        PG_RETURN_BOOL(enum_cmp_internal(a, b, fcinfo) >= 0);
}

Datum
enum_gt(PG_FUNCTION_ARGS)
{
        Oid                     a = PG_GETARG_OID(0);
        Oid                     b = PG_GETARG_OID(1);

        PG_RETURN_BOOL(enum_cmp_internal(a, b, fcinfo) > 0);
}

Datum
enum_smaller(PG_FUNCTION_ARGS)
{
        Oid                     a = PG_GETARG_OID(0);
        Oid                     b = PG_GETARG_OID(1);

        PG_RETURN_OID(enum_cmp_internal(a, b, fcinfo) < 0 ? a : b);
}

Datum
enum_larger(PG_FUNCTION_ARGS)
{
        Oid                     a = PG_GETARG_OID(0);
        Oid                     b = PG_GETARG_OID(1);

        PG_RETURN_OID(enum_cmp_internal(a, b, fcinfo) > 0 ? a : b);
}

Datum
enum_cmp(PG_FUNCTION_ARGS)
{
        Oid                     a = PG_GETARG_OID(0);
        Oid                     b = PG_GETARG_OID(1);

        PG_RETURN_INT32(enum_cmp_internal(a, b, fcinfo));
}

/* Enum programming support functions */

/*
 * enum_endpoint: common code for enum_first/enum_last
 */
static Oid
enum_endpoint(Oid enumtypoid, ScanDirection direction)
{
        Relation        enum_rel;
        Relation        enum_idx;
        SysScanDesc enum_scan;
        HeapTuple       enum_tuple;
        ScanKeyData skey;
        Oid                     minmax;

        /*
         * Find the first/last enum member using pg_enum_typid_sortorder_index.
         * Note we must not use the syscache.  See comments for RenumberEnumType
         * in catalog/pg_enum.c for more info.
         */
        ScanKeyInit(&skey,
                                Anum_pg_enum_enumtypid,
                                BTEqualStrategyNumber, F_OIDEQ,
                                ObjectIdGetDatum(enumtypoid));

        enum_rel = table_open(EnumRelationId, AccessShareLock);
        enum_idx = index_open(EnumTypIdSortOrderIndexId, AccessShareLock);
        enum_scan = systable_beginscan_ordered(enum_rel, enum_idx, NULL,
                                                                                   1, &skey);

        enum_tuple = systable_getnext_ordered(enum_scan, direction);
        if (HeapTupleIsValid(enum_tuple))
        {
                /* check it's safe to use in SQL */
                check_safe_enum_use(enum_tuple);
                minmax = ((Form_pg_enum) GETSTRUCT(enum_tuple))->oid;
        }
        else
        {
                /* should only happen with an empty enum */
                minmax = InvalidOid;
        }

        systable_endscan_ordered(enum_scan);
        index_close(enum_idx, AccessShareLock);
        table_close(enum_rel, AccessShareLock);

        return minmax;
}

Datum
enum_first(PG_FUNCTION_ARGS)
{
        Oid                     enumtypoid;
        Oid                     min;

        /*
         * We rely on being able to get the specific enum type from the calling
         * expression tree.  Notice that the actual value of the argument isn't
         * examined at all; in particular it might be NULL.
         */
        enumtypoid = get_fn_expr_argtype(fcinfo->flinfo, 0);
        if (enumtypoid == InvalidOid)
                ereport(ERROR,
                                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                 errmsg("could not determine actual enum type")));

        /* Get the OID using the index */
        min = enum_endpoint(enumtypoid, ForwardScanDirection);

        if (!OidIsValid(min))
                ereport(ERROR,
                                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                 errmsg("enum %s contains no values",
                                                format_type_be(enumtypoid))));

        PG_RETURN_OID(min);
}

Datum
enum_last(PG_FUNCTION_ARGS)
{
        Oid                     enumtypoid;
        Oid                     max;

        /*
         * We rely on being able to get the specific enum type from the calling
         * expression tree.  Notice that the actual value of the argument isn't
         * examined at all; in particular it might be NULL.
         */
        enumtypoid = get_fn_expr_argtype(fcinfo->flinfo, 0);
        if (enumtypoid == InvalidOid)
                ereport(ERROR,
                                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                 errmsg("could not determine actual enum type")));

        /* Get the OID using the index */
        max = enum_endpoint(enumtypoid, BackwardScanDirection);

        if (!OidIsValid(max))
                ereport(ERROR,
                                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                 errmsg("enum %s contains no values",
                                                format_type_be(enumtypoid))));

        PG_RETURN_OID(max);
}

/* 2-argument variant of enum_range */
Datum
enum_range_bounds(PG_FUNCTION_ARGS)
{
        Oid                     lower;
        Oid                     upper;
        Oid                     enumtypoid;

        if (PG_ARGISNULL(0))
                lower = InvalidOid;
        else
                lower = PG_GETARG_OID(0);
        if (PG_ARGISNULL(1))
                upper = InvalidOid;
        else
                upper = PG_GETARG_OID(1);

        /*
         * We rely on being able to get the specific enum type from the calling
         * expression tree.  The generic type mechanism should have ensured that
         * both are of the same type.
         */
        enumtypoid = get_fn_expr_argtype(fcinfo->flinfo, 0);
        if (enumtypoid == InvalidOid)
                ereport(ERROR,
                                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                 errmsg("could not determine actual enum type")));

        PG_RETURN_ARRAYTYPE_P(enum_range_internal(enumtypoid, lower, upper));
}

/* 1-argument variant of enum_range */
Datum
enum_range_all(PG_FUNCTION_ARGS)
{
        Oid                     enumtypoid;

        /*
         * We rely on being able to get the specific enum type from the calling
         * expression tree.  Notice that the actual value of the argument isn't
         * examined at all; in particular it might be NULL.
         */
        enumtypoid = get_fn_expr_argtype(fcinfo->flinfo, 0);
        if (enumtypoid == InvalidOid)
                ereport(ERROR,
                                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                 errmsg("could not determine actual enum type")));

        PG_RETURN_ARRAYTYPE_P(enum_range_internal(enumtypoid,
                                                                                          InvalidOid, InvalidOid));
}

static ArrayType *
enum_range_internal(Oid enumtypoid, Oid lower, Oid upper)
{
        ArrayType  *result;
        Relation        enum_rel;
        Relation        enum_idx;
        SysScanDesc enum_scan;
        HeapTuple       enum_tuple;
        ScanKeyData skey;
        Datum      *elems;
        int                     max,
                                cnt;
        bool            left_found;

        /*
         * Scan the enum members in order using pg_enum_typid_sortorder_index.
         * Note we must not use the syscache.  See comments for RenumberEnumType
         * in catalog/pg_enum.c for more info.
         */
        ScanKeyInit(&skey,
                                Anum_pg_enum_enumtypid,
                                BTEqualStrategyNumber, F_OIDEQ,
                                ObjectIdGetDatum(enumtypoid));

        enum_rel = table_open(EnumRelationId, AccessShareLock);
        enum_idx = index_open(EnumTypIdSortOrderIndexId, AccessShareLock);
        enum_scan = systable_beginscan_ordered(enum_rel, enum_idx, NULL, 1, &skey);

        max = 64;
        elems = (Datum *) palloc(max * sizeof(Datum));
        cnt = 0;
        left_found = !OidIsValid(lower);

        while (HeapTupleIsValid(enum_tuple = systable_getnext_ordered(enum_scan, ForwardScanDirection)))
        {
                Oid                     enum_oid = ((Form_pg_enum) GETSTRUCT(enum_tuple))->oid;

                if (!left_found && lower == enum_oid)
                        left_found = true;

                if (left_found)
                {
                        /* check it's safe to use in SQL */
                        check_safe_enum_use(enum_tuple);

                        if (cnt >= max)
                        {
                                max *= 2;
                                elems = (Datum *) repalloc(elems, max * sizeof(Datum));
                        }

                        elems[cnt++] = ObjectIdGetDatum(enum_oid);
                }

                if (OidIsValid(upper) && upper == enum_oid)
                        break;
        }

        systable_endscan_ordered(enum_scan);
        index_close(enum_idx, AccessShareLock);
        table_close(enum_rel, AccessShareLock);

        /* and build the result array */
        /* note this hardwires some details about the representation of Oid */
        result = construct_array(elems, cnt, enumtypoid,
                                                         sizeof(Oid), true, TYPALIGN_INT);

        pfree(elems);

        return result;
}