hashvalidate.c

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/*-------------------------------------------------------------------------
 *
 * hashvalidate.c
 *    Opclass validator for hash.
 *
 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/backend/access/hash/hashvalidate.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "access/amvalidate.h"
#include "access/hash.h"
#include "access/htup_details.h"
#include "access/xact.h"
#include "catalog/pg_am.h"
#include "catalog/pg_amop.h"
#include "catalog/pg_amproc.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_opfamily.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "parser/parse_coerce.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
#include "utils/regproc.h"
#include "utils/syscache.h"
 
 
static bool check_hash_func_signature(Oid funcid, int16 amprocnum, Oid argtype);
 
 
/*
 * Validator for a hash opclass.
 *
 * Some of the checks done here cover the whole opfamily, and therefore are
 * redundant when checking each opclass in a family.  But they don't run long
 * enough to be much of a problem, so we accept the duplication rather than
 * complicate the amvalidate API.
 */
bool
hashvalidate(Oid opclassoid)
{
    bool        result = true;
    HeapTuple   classtup;
    Form_pg_opclass classform;
    Oid         opfamilyoid;
    Oid         opcintype;
    char       *opclassname;
    HeapTuple   familytup;
    Form_pg_opfamily familyform;
    char       *opfamilyname;
    CatCList   *proclist,
               *oprlist;
    List       *grouplist;
    OpFamilyOpFuncGroup *opclassgroup;
    List       *hashabletypes = NIL;
    int         i;
    ListCell   *lc;
 
    /* Fetch opclass information */
    classtup = SearchSysCache1(CLAOID, ObjectIdGetDatum(opclassoid));
    if (!HeapTupleIsValid(classtup))
        elog(ERROR, "cache lookup failed for operator class %u", opclassoid);
    classform = (Form_pg_opclass) GETSTRUCT(classtup);
 
    opfamilyoid = classform->opcfamily;
    opcintype = classform->opcintype;
    opclassname = NameStr(classform->opcname);
 
    /* Fetch opfamily information */
    familytup = SearchSysCache1(OPFAMILYOID, ObjectIdGetDatum(opfamilyoid));
    if (!HeapTupleIsValid(familytup))
        elog(ERROR, "cache lookup failed for operator family %u", opfamilyoid);
    familyform = (Form_pg_opfamily) GETSTRUCT(familytup);
 
    opfamilyname = NameStr(familyform->opfname);
 
    /* Fetch all operators and support functions of the opfamily */
    oprlist = SearchSysCacheList1(AMOPSTRATEGY, ObjectIdGetDatum(opfamilyoid));
    proclist = SearchSysCacheList1(AMPROCNUM, ObjectIdGetDatum(opfamilyoid));
 
    /* Check individual support functions */
    for (i = 0; i < proclist->n_members; i++)
    {
        HeapTuple   proctup = &proclist->members[i]->tuple;
        Form_pg_amproc procform = (Form_pg_amproc) GETSTRUCT(proctup);
 
        /*
         * All hash functions should be registered with matching left/right
         * types
         */
        if (procform->amproclefttype != procform->amprocrighttype)
        {
            ereport(INFO,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("operator family \"%s\" of access method %s contains support function %s with different left and right input types",
                            opfamilyname, "hash",
                            format_procedure(procform->amproc))));
            result = false;
        }
 
        /* Check procedure numbers and function signatures */
        switch (procform->amprocnum)
        {
            case HASHSTANDARD_PROC:
            case HASHEXTENDED_PROC:
                if (!check_hash_func_signature(procform->amproc, procform->amprocnum,
                                               procform->amproclefttype))
                {
                    ereport(INFO,
                            (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                             errmsg("operator family \"%s\" of access method %s contains function %s with wrong signature for support number %d",
                                    opfamilyname, "hash",
                                    format_procedure(procform->amproc),
                                    procform->amprocnum)));
                    result = false;
                }
                else
                {
                    /* Remember which types we can hash */
                    hashabletypes =
                        list_append_unique_oid(hashabletypes,
                                               procform->amproclefttype);
                }
                break;
            case HASHOPTIONS_PROC:
                if (!check_amoptsproc_signature(procform->amproc))
                    result = false;
                break;
            default:
                ereport(INFO,
                        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                         errmsg("operator family \"%s\" of access method %s contains function %s with invalid support number %d",
                                opfamilyname, "hash",
                                format_procedure(procform->amproc),
                                procform->amprocnum)));
                result = false;
                break;
        }
    }
 
    /* Check individual operators */
    for (i = 0; i < oprlist->n_members; i++)
    {
        HeapTuple   oprtup = &oprlist->members[i]->tuple;
        Form_pg_amop oprform = (Form_pg_amop) GETSTRUCT(oprtup);
 
        /* Check that only allowed strategy numbers exist */
        if (oprform->amopstrategy < 1 ||
            oprform->amopstrategy > HTMaxStrategyNumber)
        {
            ereport(INFO,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("operator family \"%s\" of access method %s contains operator %s with invalid strategy number %d",
                            opfamilyname, "hash",
                            format_operator(oprform->amopopr),
                            oprform->amopstrategy)));
            result = false;
        }
 
        /* hash doesn't support ORDER BY operators */
        if (oprform->amoppurpose != AMOP_SEARCH ||
            OidIsValid(oprform->amopsortfamily))
        {
            ereport(INFO,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("operator family \"%s\" of access method %s contains invalid ORDER BY specification for operator %s",
                            opfamilyname, "hash",
                            format_operator(oprform->amopopr))));
            result = false;
        }
 
        /* Check operator signature --- same for all hash strategies */
        if (!check_amop_signature(oprform->amopopr, BOOLOID,
                                  oprform->amoplefttype,
                                  oprform->amoprighttype))
        {
            ereport(INFO,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("operator family \"%s\" of access method %s contains operator %s with wrong signature",
                            opfamilyname, "hash",
                            format_operator(oprform->amopopr))));
            result = false;
        }
 
        /* There should be relevant hash functions for each datatype */
        if (!list_member_oid(hashabletypes, oprform->amoplefttype) ||
            !list_member_oid(hashabletypes, oprform->amoprighttype))
        {
            ereport(INFO,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("operator family \"%s\" of access method %s lacks support function for operator %s",
                            opfamilyname, "hash",
                            format_operator(oprform->amopopr))));
            result = false;
        }
    }
 
    /* Now check for inconsistent groups of operators/functions */
    grouplist = identify_opfamily_groups(oprlist, proclist);
    opclassgroup = NULL;
    foreach(lc, grouplist)
    {
        OpFamilyOpFuncGroup *thisgroup = (OpFamilyOpFuncGroup *) lfirst(lc);
 
        /* Remember the group exactly matching the test opclass */
        if (thisgroup->lefttype == opcintype &&
            thisgroup->righttype == opcintype)
            opclassgroup = thisgroup;
 
        /*
         * Complain if there seems to be an incomplete set of operators for
         * this datatype pair (implying that we have a hash function but no
         * operator).
         */
        if (thisgroup->operatorset != (1 << HTEqualStrategyNumber))
        {
            ereport(INFO,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("operator family \"%s\" of access method %s is missing operator(s) for types %s and %s",
                            opfamilyname, "hash",
                            format_type_be(thisgroup->lefttype),
                            format_type_be(thisgroup->righttype))));
            result = false;
        }
    }
 
    /* Check that the originally-named opclass is supported */
    /* (if group is there, we already checked it adequately above) */
    if (!opclassgroup)
    {
        ereport(INFO,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("operator class \"%s\" of access method %s is missing operator(s)",
                        opclassname, "hash")));
        result = false;
    }
 
    /*
     * Complain if the opfamily doesn't have entries for all possible
     * combinations of its supported datatypes.  While missing cross-type
     * operators are not fatal, it seems reasonable to insist that all
     * built-in hash opfamilies be complete.
     */
    if (list_length(grouplist) !=
        list_length(hashabletypes) * list_length(hashabletypes))
    {
        ereport(INFO,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("operator family \"%s\" of access method %s is missing cross-type operator(s)",
                        opfamilyname, "hash")));
        result = false;
    }
 
    ReleaseCatCacheList(proclist);
    ReleaseCatCacheList(oprlist);
    ReleaseSysCache(familytup);
    ReleaseSysCache(classtup);
 
    return result;
}
 
 
/*
 * We need a custom version of check_amproc_signature because of assorted
 * hacks in the core hash opclass definitions.
 */
static bool
check_hash_func_signature(Oid funcid, int16 amprocnum, Oid argtype)
{
    bool        result = true;
    Oid         restype;
    int16       nargs;
    HeapTuple   tp;
    Form_pg_proc procform;
 
    switch (amprocnum)
    {
        case HASHSTANDARD_PROC:
            restype = INT4OID;
            nargs = 1;
            break;
 
        case HASHEXTENDED_PROC:
            restype = INT8OID;
            nargs = 2;
            break;
 
        default:
            elog(ERROR, "invalid amprocnum");
    }
 
    tp = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
    if (!HeapTupleIsValid(tp))
        elog(ERROR, "cache lookup failed for function %u", funcid);
    procform = (Form_pg_proc) GETSTRUCT(tp);
 
    if (procform->prorettype != restype || procform->proretset ||
        procform->pronargs != nargs)
        result = false;
 
    if (!IsBinaryCoercible(argtype, procform->proargtypes.values[0]))
    {
        /*
         * Some of the built-in hash opclasses cheat by using hash functions
         * that are different from but physically compatible with the opclass
         * datatype.  In some of these cases, even a "binary coercible" check
         * fails because there's no relevant cast.  For the moment, fix it by
         * having a list of allowed cases.  Test the specific function
         * identity, not just its input type, because hashvarlena() takes
         * INTERNAL and allowing any such function seems too scary.
         */
        if ((funcid == F_HASHINT4 || funcid == F_HASHINT4EXTENDED) &&
            (argtype == DATEOID ||
             argtype == XIDOID || argtype == CIDOID))
             /* okay, allowed use of hashint4() */ ;
        else if ((funcid == F_HASHINT8 || funcid == F_HASHINT8EXTENDED) &&
                 (argtype == XID8OID))
             /* okay, allowed use of hashint8() */ ;
        else if ((funcid == F_TIMESTAMP_HASH ||
                  funcid == F_TIMESTAMP_HASH_EXTENDED) &&
                 argtype == TIMESTAMPTZOID)
             /* okay, allowed use of timestamp_hash() */ ;
        else if ((funcid == F_HASHCHAR || funcid == F_HASHCHAREXTENDED) &&
                 argtype == BOOLOID)
             /* okay, allowed use of hashchar() */ ;
        else if ((funcid == F_HASHVARLENA || funcid == F_HASHVARLENAEXTENDED) &&
                 argtype == BYTEAOID)
             /* okay, allowed use of hashvarlena() */ ;
        else
            result = false;
    }
 
    /* If function takes a second argument, it must be for a 64-bit salt. */
    if (nargs == 2 && procform->proargtypes.values[1] != INT8OID)
        result = false;
 
    ReleaseSysCache(tp);
    return result;
}
 
/*
 * Prechecking function for adding operators/functions to a hash opfamily.
 */
void
hashadjustmembers(Oid opfamilyoid,
                  Oid opclassoid,
                  List *operators,
                  List *functions)
{
    Oid         opcintype;
    ListCell   *lc;
 
    /*
     * Hash operators and required support functions are always "loose"
     * members of the opfamily if they are cross-type.  If they are not
     * cross-type, we prefer to tie them to the appropriate opclass ... but if
     * the user hasn't created one, we can't do that, and must fall back to
     * using the opfamily dependency.  (We mustn't force creation of an
     * opclass in such a case, as leaving an incomplete opclass laying about
     * would be bad.  Throwing an error is another undesirable alternative.)
     *
     * This behavior results in a bit of a dump/reload hazard, in that the
     * order of restoring objects could affect what dependencies we end up
     * with.  pg_dump's existing behavior will preserve the dependency choices
     * in most cases, but not if a cross-type operator has been bound tightly
     * into an opclass.  That's a mistake anyway, so silently "fixing" it
     * isn't awful.
     *
     * Optional support functions are always "loose" family members.
     *
     * To avoid repeated lookups, we remember the most recently used opclass's
     * input type.
     */
    if (OidIsValid(opclassoid))
    {
        /* During CREATE OPERATOR CLASS, need CCI to see the pg_opclass row */
        CommandCounterIncrement();
        opcintype = get_opclass_input_type(opclassoid);
    }
    else
        opcintype = InvalidOid;
 
    /*
     * We handle operators and support functions almost identically, so rather
     * than duplicate this code block, just join the lists.
     */
    foreach(lc, list_concat_copy(operators, functions))
    {
        OpFamilyMember *op = (OpFamilyMember *) lfirst(lc);
 
        if (op->is_func && op->number != HASHSTANDARD_PROC)
        {
            /* Optional support proc, so always a soft family dependency */
            op->ref_is_hard = false;
            op->ref_is_family = true;
            op->refobjid = opfamilyoid;
        }
        else if (op->lefttype != op->righttype)
        {
            /* Cross-type, so always a soft family dependency */
            op->ref_is_hard = false;
            op->ref_is_family = true;
            op->refobjid = opfamilyoid;
        }
        else
        {
            /* Not cross-type; is there a suitable opclass? */
            if (op->lefttype != opcintype)
            {
                /* Avoid repeating this expensive lookup, even if it fails */
                opcintype = op->lefttype;
                opclassoid = opclass_for_family_datatype(HASH_AM_OID,
                                                         opfamilyoid,
                                                         opcintype);
            }
            if (OidIsValid(opclassoid))
            {
                /* Hard dependency on opclass */
                op->ref_is_hard = true;
                op->ref_is_family = false;
                op->refobjid = opclassoid;
            }
            else
            {
                /* We're stuck, so make a soft dependency on the opfamily */
                op->ref_is_hard = false;
                op->ref_is_family = true;
                op->refobjid = opfamilyoid;
            }
        }
    }
}