map_verify.go

/*
 * Atree - Scalable Arrays and Ordered Maps
 *
 * Copyright Flow Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package atree

import (
	"bytes"
	"fmt"
	"reflect"
	"slices"
	"sort"
)

func VerifyMap(
	m *OrderedMap,
	address Address,
	typeInfo TypeInfo,
	tic TypeInfoComparator,
	hip HashInputProvider,
	inlineEnabled bool,
) error {
	return verifyMap(m, address, typeInfo, tic, hip, inlineEnabled, map[SlabID]struct{}{})
}

func verifyMap(
	m *OrderedMap,
	address Address,
	typeInfo TypeInfo,
	tic TypeInfoComparator,
	hip HashInputProvider,
	inlineEnabled bool,
	slabIDs map[SlabID]struct{},
) error {

	// Verify map address (independent of array inlined status)
	if address != m.Address() {
		return NewFatalError(fmt.Errorf("map address %v, got %v", address, m.Address()))
	}

	// Verify map value ID (independent of array inlined status)
	err := verifyMapValueID(m)
	if err != nil {
		return err
	}

	// Verify map slab ID (dependent of array inlined status)
	err = verifyMapSlabID(m)
	if err != nil {
		return err
	}

	// Verify map extra data
	extraData := m.root.ExtraData()
	if extraData == nil {
		return NewFatalError(fmt.Errorf("root slab %d doesn't have extra data", m.root.SlabID()))
	}

	// Verify that extra data has correct type information
	if typeInfo != nil && !tic(extraData.TypeInfo, typeInfo) {
		return NewFatalError(
			fmt.Errorf(
				"root slab %d type information %v, want %v",
				m.root.SlabID(),
				extraData.TypeInfo,
				typeInfo,
			))
	}

	// Verify that extra data has seed
	if extraData.Seed == 0 {
		return NewFatalError(fmt.Errorf("root slab %d seed is uninitialized", m.root.SlabID()))
	}

	v := &mapVerifier{
		storage:         m.Storage,
		address:         address,
		digesterBuilder: m.digesterBuilder,
		tic:             tic,
		hip:             hip,
		inlineEnabled:   inlineEnabled,
	}

	computedCount, dataSlabIDs, nextDataSlabIDs, firstKeys, err := v.verifySlab(
		m.root, 0, nil, []SlabID{}, []SlabID{}, []Digest{}, slabIDs)
	if err != nil {
		// Don't need to wrap error as external error because err is already categorized by verifySlab().
		return err
	}

	// Verify that extra data has correct count
	if computedCount != extraData.Count {
		return NewFatalError(
			fmt.Errorf(
				"root slab %d count %d is wrong, want %d",
				m.root.SlabID(),
				extraData.Count,
				computedCount,
			))
	}

	// Verify next data slab ids
	if !reflect.DeepEqual(dataSlabIDs[1:], nextDataSlabIDs) {
		return NewFatalError(fmt.Errorf("chained next data slab ids %v are wrong, want %v",
			nextDataSlabIDs, dataSlabIDs[1:]))
	}

	// Verify data slabs' first keys are sorted
	if !sort.SliceIsSorted(firstKeys, func(i, j int) bool {
		return firstKeys[i] < firstKeys[j]
	}) {
		return NewFatalError(fmt.Errorf("chained first keys %v are not sorted", firstKeys))
	}

	// Verify data slabs' first keys are unique
	if len(firstKeys) > 1 {
		prev := firstKeys[0]
		for _, d := range firstKeys[1:] {
			if prev == d {
				return NewFatalError(fmt.Errorf("chained first keys %v are not unique", firstKeys))
			}
			prev = d
		}
	}

	return nil
}

type mapVerifier struct {
	storage         SlabStorage
	address         Address
	digesterBuilder DigesterBuilder
	tic             TypeInfoComparator
	hip             HashInputProvider
	inlineEnabled   bool
}

func (v *mapVerifier) verifySlab(
	slab MapSlab,
	level int,
	headerFromParentSlab *MapSlabHeader,
	dataSlabIDs []SlabID,
	nextDataSlabIDs []SlabID,
	firstKeys []Digest,
	slabIDs map[SlabID]struct{},
) (
	elementCount uint64,
	_dataSlabIDs []SlabID,
	_nextDataSlabIDs []SlabID,
	_firstKeys []Digest,
	err error,
) {

	id := slab.Header().slabID

	// Verify SlabID is unique
	if _, exist := slabIDs[id]; exist {
		return 0, nil, nil, nil, NewFatalError(fmt.Errorf("found duplicate slab ID %s", id))
	}

	slabIDs[id] = struct{}{}

	// Verify slab address (independent of map inlined status)
	if v.address != id.address {
		return 0, nil, nil, nil, NewFatalError(fmt.Errorf("map slab address %v, got %v", v.address, id.address))
	}

	// Verify that inlined slab is not in storage
	if slab.Inlined() {
		_, exist, err := v.storage.Retrieve(id)
		if err != nil {
			// Wrap err as external error (if needed) because err is returned by Storage interface.
			return 0, nil, nil, nil, wrapErrorAsExternalErrorIfNeeded(err)
		}
		if exist {
			return 0, nil, nil, nil, NewFatalError(fmt.Errorf("inlined slab %s is in storage", id))
		}
	}

	if level > 0 {
		// Verify that non-root slab doesn't have extra data.
		if slab.ExtraData() != nil {
			return 0, nil, nil, nil, NewFatalError(fmt.Errorf("non-root slab %d has extra data", id))
		}

		// Verify that non-root slab doesn't underflow
		if underflowSize, underflow := slab.IsUnderflow(); underflow {
			return 0, nil, nil, nil, NewFatalError(fmt.Errorf("slab %d underflows by %d bytes", id, underflowSize))
		}

	}

	// Verify that slab doesn't overflow
	if slab.IsFull() {
		return 0, nil, nil, nil, NewFatalError(fmt.Errorf("slab %d overflows", id))
	}

	// Verify that header is in sync with header from parent slab
	if headerFromParentSlab != nil {
		if !reflect.DeepEqual(*headerFromParentSlab, slab.Header()) {
			return 0, nil, nil, nil, NewFatalError(
				fmt.Errorf("slab %d header %+v is different from header %+v from parent slab",
					id, slab.Header(), headerFromParentSlab))
		}
	}

	switch slab := slab.(type) {
	case *MapDataSlab:
		return v.verifyDataSlab(slab, level, dataSlabIDs, nextDataSlabIDs, firstKeys, slabIDs)

	case *MapMetaDataSlab:
		return v.verifyMetaDataSlab(slab, level, dataSlabIDs, nextDataSlabIDs, firstKeys, slabIDs)

	default:
		return 0, nil, nil, nil, NewFatalError(fmt.Errorf("MapSlab is either *MapDataSlab or *MapMetaDataSlab, got %T", slab))
	}
}

func (v *mapVerifier) verifyDataSlab(
	dataSlab *MapDataSlab,
	level int,
	dataSlabIDs []SlabID,
	nextDataSlabIDs []SlabID,
	firstKeys []Digest,
	slabIDs map[SlabID]struct{},
) (
	elementCount uint64,
	_dataSlabIDs []SlabID,
	_nextDataSlabIDs []SlabID,
	_firstKeys []Digest,
	err error,
) {
	id := dataSlab.header.slabID

	if !dataSlab.IsData() {
		return 0, nil, nil, nil, NewFatalError(fmt.Errorf("MapDataSlab %s is not data", id))
	}

	// Verify data slab's elements
	elementCount, elementSize, err := v.verifyElements(id, dataSlab.elements, 0, nil, slabIDs)
	if err != nil {
		// Don't need to wrap error as external error because err is already categorized by verifyElements().
		return 0, nil, nil, nil, err
	}

	// Verify slab's first key
	if dataSlab.elements.firstKey() != dataSlab.header.firstKey {
		return 0, nil, nil, nil, NewFatalError(
			fmt.Errorf("data slab %d header first key %d is wrong, want %d",
				id, dataSlab.header.firstKey, dataSlab.elements.firstKey()))
	}

	// Verify that only root slab can be inlined
	if dataSlab.Inlined() {
		if level > 0 {
			return 0, nil, nil, nil, NewFatalError(fmt.Errorf("non-root slab %s is inlined", id))
		}
		if dataSlab.extraData == nil {
			return 0, nil, nil, nil, NewFatalError(fmt.Errorf("inlined slab %s doesn't have extra data", id))
		}
		if dataSlab.next != SlabIDUndefined {
			return 0, nil, nil, nil, NewFatalError(fmt.Errorf("inlined slab %s has next slab ID", id))
		}
	}

	// Verify that aggregated element size + slab prefix is the same as header.size
	computedSize := uint32(mapDataSlabPrefixSize)
	if level == 0 {
		computedSize = uint32(mapRootDataSlabPrefixSize)
		if dataSlab.Inlined() {
			computedSize = uint32(inlinedMapDataSlabPrefixSize)
		}
	}
	computedSize += elementSize

	if computedSize != dataSlab.header.size {
		return 0, nil, nil, nil, NewFatalError(
			fmt.Errorf("data slab %d header size %d is wrong, want %d",
				id, dataSlab.header.size, computedSize))
	}

	// Verify any size flag
	if dataSlab.anySize {
		return 0, nil, nil, nil, NewFatalError(
			fmt.Errorf("data slab %d anySize %t is wrong, want false",
				id, dataSlab.anySize))
	}

	// Verify collision group flag
	if dataSlab.collisionGroup {
		return 0, nil, nil, nil, NewFatalError(
			fmt.Errorf("data slab %d collisionGroup %t is wrong, want false",
				id, dataSlab.collisionGroup))
	}

	dataSlabIDs = append(dataSlabIDs, id)

	if dataSlab.next != SlabIDUndefined {
		nextDataSlabIDs = append(nextDataSlabIDs, dataSlab.next)
	}

	firstKeys = append(firstKeys, dataSlab.header.firstKey)

	return elementCount, dataSlabIDs, nextDataSlabIDs, firstKeys, nil
}

func (v *mapVerifier) verifyMetaDataSlab(
	metaSlab *MapMetaDataSlab,
	level int,
	dataSlabIDs []SlabID,
	nextDataSlabIDs []SlabID,
	firstKeys []Digest,
	slabIDs map[SlabID]struct{},
) (
	elementCount uint64,
	_dataSlabIDs []SlabID,
	_nextDataSlabIDs []SlabID,
	_firstKeys []Digest,
	err error,
) {
	id := metaSlab.header.slabID

	if metaSlab.IsData() {
		return 0, nil, nil, nil, NewFatalError(fmt.Errorf("MapMetaDataSlab %s is data", id))
	}

	if metaSlab.Inlined() {
		return 0, nil, nil, nil, NewFatalError(fmt.Errorf("MapMetaDataSlab %s can't be inlined", id))
	}

	if level == 0 {
		// Verify that root slab has more than one child slabs
		if len(metaSlab.childrenHeaders) < 2 {
			return 0, nil, nil, nil, NewFatalError(
				fmt.Errorf("root metadata slab %d has %d children, want at least 2 children ",
					id, len(metaSlab.childrenHeaders)))
		}
	}

	elementCount = 0
	for i := range metaSlab.childrenHeaders {
		h := metaSlab.childrenHeaders[i]

		childSlab, err := getMapSlab(v.storage, h.slabID)
		if err != nil {
			// Don't need to wrap error as external error because err is already categorized by getMapSlab().
			return 0, nil, nil, nil, err
		}

		// Verify child slabs
		count := uint64(0)
		count, dataSlabIDs, nextDataSlabIDs, firstKeys, err =
			v.verifySlab(childSlab, level+1, &h, dataSlabIDs, nextDataSlabIDs, firstKeys, slabIDs)
		if err != nil {
			// Don't need to wrap error as external error because err is already categorized by verifySlab().
			return 0, nil, nil, nil, err
		}

		elementCount += count
	}

	// Verify slab header first key
	if metaSlab.childrenHeaders[0].firstKey != metaSlab.header.firstKey {
		return 0, nil, nil, nil, NewFatalError(
			fmt.Errorf("metadata slab %d header first key %d is wrong, want %d",
				id, metaSlab.header.firstKey, metaSlab.childrenHeaders[0].firstKey))
	}

	// Verify that child slab's first keys are sorted.
	sortedHKey := sort.SliceIsSorted(metaSlab.childrenHeaders, func(i, j int) bool {
		return metaSlab.childrenHeaders[i].firstKey < metaSlab.childrenHeaders[j].firstKey
	})
	if !sortedHKey {
		return 0, nil, nil, nil, NewFatalError(fmt.Errorf("metadata slab %d child slab's first key isn't sorted %+v", id, metaSlab.childrenHeaders))
	}

	// Verify that child slab's first keys are unique.
	if len(metaSlab.childrenHeaders) > 1 {
		prev := metaSlab.childrenHeaders[0].firstKey
		for _, h := range metaSlab.childrenHeaders[1:] {
			if prev == h.firstKey {
				return 0, nil, nil, nil, NewFatalError(
					fmt.Errorf("metadata slab %d child header first key isn't unique %v",
						id, metaSlab.childrenHeaders))
			}
			prev = h.firstKey
		}
	}

	// Verify slab header's size
	computedSize := uint32(len(metaSlab.childrenHeaders)*mapSlabHeaderSize) + mapMetaDataSlabPrefixSize
	if computedSize != metaSlab.header.size {
		return 0, nil, nil, nil, NewFatalError(
			fmt.Errorf("metadata slab %d header size %d is wrong, want %d",
				id, metaSlab.header.size, computedSize))
	}

	return elementCount, dataSlabIDs, nextDataSlabIDs, firstKeys, nil
}

func (v *mapVerifier) verifyElements(
	id SlabID,
	elements elements,
	digestLevel uint,
	hkeyPrefixes []Digest,
	slabIDs map[SlabID]struct{},
) (
	elementCount uint64,
	elementSize uint32,
	err error,
) {

	switch elems := elements.(type) {
	case *hkeyElements:
		return v.verifyHkeyElements(id, elems, digestLevel, hkeyPrefixes, slabIDs)
	case *singleElements:
		return v.verifySingleElements(id, elems, digestLevel, hkeyPrefixes, slabIDs)
	default:
		return 0, 0, NewFatalError(fmt.Errorf("slab %d has unknown elements type %T at digest level %d", id, elements, digestLevel))
	}
}

func (v *mapVerifier) verifyHkeyElements(
	id SlabID,
	elements *hkeyElements,
	digestLevel uint,
	hkeyPrefixes []Digest,
	slabIDs map[SlabID]struct{},
) (
	elementCount uint64,
	elementSize uint32,
	err error,
) {

	// Verify element's level
	if digestLevel != elements.level {
		return 0, 0, NewFatalError(
			fmt.Errorf("data slab %d elements digest level %d is wrong, want %d",
				id, elements.level, digestLevel))
	}

	// Verify number of hkeys is the same as number of elements
	if len(elements.hkeys) != len(elements.elems) {
		return 0, 0, NewFatalError(
			fmt.Errorf("data slab %d hkeys count %d is wrong, want %d",
				id, len(elements.hkeys), len(elements.elems)))
	}

	// Verify hkeys are sorted
	if !sort.SliceIsSorted(elements.hkeys, func(i, j int) bool {
		return elements.hkeys[i] < elements.hkeys[j]
	}) {
		return 0, 0, NewFatalError(fmt.Errorf("data slab %d hkeys is not sorted %v", id, elements.hkeys))
	}

	// Verify hkeys are unique
	if len(elements.hkeys) > 1 {
		prev := elements.hkeys[0]
		for _, d := range elements.hkeys[1:] {
			if prev == d {
				return 0, 0, NewFatalError(fmt.Errorf("data slab %d hkeys is not unique %v", id, elements.hkeys))
			}
			prev = d
		}
	}

	elementSize = uint32(hkeyElementsPrefixSize)

	for i, e := range elements.elems {

		hkeys := slices.Clone(hkeyPrefixes)
		hkeys = append(hkeys, elements.hkeys[i])

		elementSize += digestSize

		// Verify element size is <= inline size
		if digestLevel == 0 {
			if e.Size() > uint32(maxInlineMapElementSize) {
				return 0, 0, NewFatalError(
					fmt.Errorf("data slab %d element %s size %d is too large, want < %d",
						id, e, e.Size(), maxInlineMapElementSize))
			}
		}

		switch e := e.(type) {
		case elementGroup:
			group, err := e.Elements(v.storage)
			if err != nil {
				// Don't need to wrap error as external error because err is already categorized by elementGroup.Elements().
				return 0, 0, err
			}

			count, size, err := v.verifyElements(id, group, digestLevel+1, hkeys, slabIDs)
			if err != nil {
				// Don't need to wrap error as external error because err is already categorized by verifyElements().
				return 0, 0, err
			}

			if _, ok := e.(*inlineCollisionGroup); ok {
				size += inlineCollisionGroupPrefixSize
			} else {
				size = externalCollisionGroupPrefixSize + 2 + 1 + 16
			}

			// Verify element group size
			if size != e.Size() {
				return 0, 0, NewFatalError(fmt.Errorf("data slab %d element %s size %d is wrong, want %d", id, e, e.Size(), size))
			}

			elementSize += e.Size()

			elementCount += count

		case *singleElement:
			// Verify element
			computedSize, maxDigestLevel, err := v.verifySingleElement(e, hkeys, slabIDs)
			if err != nil {
				// Don't need to wrap error as external error because err is already categorized by verifySingleElement().
				return 0, 0, fmt.Errorf("data slab %d: %w", id, err)
			}

			// Verify digest level
			if digestLevel >= maxDigestLevel {
				return 0, 0, NewFatalError(
					fmt.Errorf("data slab %d, hkey elements %s: digest level %d is wrong, want < %d",
						id, elements, digestLevel, maxDigestLevel))
			}

			elementSize += computedSize

			elementCount++

		default:
			return 0, 0, NewFatalError(fmt.Errorf("data slab %d element type %T is wrong, want either elementGroup or *singleElement", id, e))
		}
	}

	// Verify elements size
	if elementSize != elements.Size() {
		return 0, 0, NewFatalError(fmt.Errorf("data slab %d elements size %d is wrong, want %d", id, elements.Size(), elementSize))
	}

	return elementCount, elementSize, nil
}

func (v *mapVerifier) verifySingleElements(
	id SlabID,
	elements *singleElements,
	digestLevel uint,
	hkeyPrefixes []Digest,
	slabIDs map[SlabID]struct{},
) (
	elementCount uint64,
	elementSize uint32,
	err error,
) {

	// Verify elements' level
	if digestLevel != elements.level {
		return 0, 0, NewFatalError(
			fmt.Errorf("data slab %d elements level %d is wrong, want %d",
				id, elements.level, digestLevel))
	}

	elementSize = singleElementsPrefixSize

	for _, e := range elements.elems {

		// Verify element
		computedSize, maxDigestLevel, err := v.verifySingleElement(e, hkeyPrefixes, slabIDs)
		if err != nil {
			// Don't need to wrap error as external error because err is already categorized by verifySingleElement().
			return 0, 0, fmt.Errorf("data slab %d: %w", id, err)
		}

		// Verify element size is <= inline size
		if e.Size() > uint32(maxInlineMapElementSize) {
			return 0, 0, NewFatalError(
				fmt.Errorf("data slab %d element %s size %d is too large, want < %d",
					id, e, e.Size(), maxInlineMapElementSize))
		}

		// Verify digest level
		if digestLevel != maxDigestLevel {
			return 0, 0, NewFatalError(
				fmt.Errorf("data slab %d single elements %s digest level %d is wrong, want %d",
					id, elements, digestLevel, maxDigestLevel))
		}

		elementSize += computedSize
	}

	// Verify elements size
	if elementSize != elements.Size() {
		return 0, 0, NewFatalError(fmt.Errorf("slab %d elements size %d is wrong, want %d", id, elements.Size(), elementSize))
	}

	return uint64(len(elements.elems)), elementSize, nil
}

func (v *mapVerifier) verifySingleElement(
	e *singleElement,
	digests []Digest,
	slabIDs map[SlabID]struct{},
) (
	size uint32,
	digestMaxLevel uint,
	err error,
) {
	// Verify key storable's size is less than size limit
	if e.key.ByteSize() > uint32(maxInlineMapKeySize) {
		return 0, 0, NewFatalError(
			fmt.Errorf(
				"map element key %s size %d exceeds size limit %d",
				e.key, e.key.ByteSize(), maxInlineMapKeySize,
			))
	}

	// Verify value storable's size is less than size limit
	valueSizeLimit := maxInlineMapValueSize(uint64(e.key.ByteSize()))
	if e.value.ByteSize() > uint32(valueSizeLimit) {
		return 0, 0, NewFatalError(
			fmt.Errorf(
				"map element value %s size %d exceeds size limit %d",
				e.value, e.value.ByteSize(), valueSizeLimit,
			))
	}

	// Verify key
	kv, err := e.key.StoredValue(v.storage)
	if err != nil {
		// Wrap err as external error (if needed) because err is returned by Stroable interface.
		return 0, 0, wrapErrorfAsExternalErrorIfNeeded(err, fmt.Sprintf("element %s key can't be converted to value", e))
	}

	err = verifyValue(kv, v.address, nil, v.tic, v.hip, v.inlineEnabled, slabIDs)
	if err != nil {
		// Don't need to wrap error as external error because err is already categorized by verifyValue().
		return 0, 0, fmt.Errorf("element %s key isn't valid: %w", e, err)
	}

	// Verify value
	vv, err := e.value.StoredValue(v.storage)
	if err != nil {
		// Wrap err as external error (if needed) because err is returned by Stroable interface.
		return 0, 0, wrapErrorfAsExternalErrorIfNeeded(err, fmt.Sprintf("element %s value can't be converted to value", e))
	}

	switch e := e.value.(type) {
	case SlabIDStorable:
		// Verify not-inlined value > inline size, or can't be inlined
		if v.inlineEnabled {
			err = verifyNotInlinedValueStatusAndSize(vv, uint32(valueSizeLimit))
			if err != nil {
				return 0, 0, err
			}
		}

	case *ArrayDataSlab:
		// Verify inlined element's inlined status
		if !e.Inlined() {
			return 0, 0, NewFatalError(fmt.Errorf("inlined array inlined status is false"))
		}

	case *MapDataSlab:
		// Verify inlined element's inlined status
		if !e.Inlined() {
			return 0, 0, NewFatalError(fmt.Errorf("inlined map inlined status is false"))
		}
	}

	err = verifyValue(vv, v.address, nil, v.tic, v.hip, v.inlineEnabled, slabIDs)
	if err != nil {
		// Don't need to wrap error as external error because err is already categorized by verifyValue().
		return 0, 0, fmt.Errorf("element %s value isn't valid: %w", e, err)
	}

	// Verify size
	computedSize := singleElementPrefixSize + e.key.ByteSize() + e.value.ByteSize()
	if computedSize != e.Size() {
		return 0, 0, NewFatalError(fmt.Errorf("element %s size %d is wrong, want %d", e, e.Size(), computedSize))
	}

	// Verify digest
	digest, err := v.digesterBuilder.Digest(v.hip, kv)
	if err != nil {
		// Wrap err as external error (if needed) because err is returned by DigesterBuilder interface.
		return 0, 0, wrapErrorfAsExternalErrorIfNeeded(err, "failed to create digester")
	}

	computedDigests, err := digest.DigestPrefix(digest.Levels())
	if err != nil {
		// Wrap err as external error (if needed) because err is returned by Digester interface.
		return 0, 0, wrapErrorfAsExternalErrorIfNeeded(err, fmt.Sprintf("failed to generate digest prefix up to level %d", digest.Levels()))
	}

	if !reflect.DeepEqual(digests, computedDigests[:len(digests)]) {
		return 0, 0, NewFatalError(fmt.Errorf("element %s digest %v is wrong, want %v", e, digests, computedDigests))
	}

	return computedSize, digest.Levels(), nil
}

func verifyValue(value Value, address Address, typeInfo TypeInfo, tic TypeInfoComparator, hip HashInputProvider, inlineEnabled bool, slabIDs map[SlabID]struct{}) error {
	switch v := value.(type) {
	case *Array:
		return verifyArray(v, address, typeInfo, tic, hip, inlineEnabled, slabIDs)
	case *OrderedMap:
		return verifyMap(v, address, typeInfo, tic, hip, inlineEnabled, slabIDs)
	}
	return nil
}

// verifyMapValueID verifies map ValueID is always the same as
// root slab's SlabID indepedent of map's inlined status.
func verifyMapValueID(m *OrderedMap) error {
	rootSlabID := m.root.Header().slabID

	vid := m.ValueID()

	if !bytes.Equal(vid[:SlabAddressLength], rootSlabID.address[:]) {
		return NewFatalError(
			fmt.Errorf(
				"expect first %d bytes of array value ID as %v, got %v",
				SlabAddressLength,
				rootSlabID.address[:],
				vid[:SlabAddressLength]))
	}

	if !bytes.Equal(vid[SlabAddressLength:], rootSlabID.index[:]) {
		return NewFatalError(
			fmt.Errorf(
				"expect second %d bytes of array value ID as %v, got %v",
				SlabIndexLength,
				rootSlabID.index[:],
				vid[SlabAddressLength:]))
	}

	return nil
}

// verifyMapSlabID verifies map SlabID is either empty for inlined map, or
// same as root slab's SlabID for not-inlined map.
func verifyMapSlabID(m *OrderedMap) error {
	sid := m.SlabID()

	if m.Inlined() {
		if sid != SlabIDUndefined {
			return NewFatalError(
				fmt.Errorf(
					"expect empty slab ID for inlined array, got %v",
					sid))
		}
		return nil
	}

	rootSlabID := m.root.Header().slabID

	if sid == SlabIDUndefined {
		return NewFatalError(
			fmt.Errorf(
				"expect non-empty slab ID for not-inlined array, got %v",
				sid))
	}

	if sid != rootSlabID {
		return NewFatalError(
			fmt.Errorf(
				"expect array slab ID same as root slab's slab ID %s, got %s",
				rootSlabID,
				sid))
	}

	return nil
}