396 lines
12 KiB
Go
396 lines
12 KiB
Go
package store
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import (
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"bytes"
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"crypto/sha256"
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"encoding/binary"
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"encoding/hex"
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"errors"
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"fmt"
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"hash/crc32"
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"io"
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"os"
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"path/filepath"
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"regexp"
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"strconv"
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"sync"
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"github.com/klauspost/compress/zstd"
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)
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const (
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segmentVersion = uint16(1)
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segmentHeaderSize = uint16(128)
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segmentTrailerSize = uint64(4)
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headerCRCOffset = 116
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segmentFileMode = 0o600
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DefaultSegmentLimit = uint64(64 << 20)
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)
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var (
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segmentMagic = [8]byte{'R', 'V', 'B', 'O', 'X', 'S', 'E', 'G'}
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castagnoliTable = crc32.MakeTable(crc32.Castagnoli)
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segmentNamePattern = regexp.MustCompile(`^[0-9a-f]{32}-[0-9]{10}\.seg$`)
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ErrInvalidSegmentRecord = errors.New("invalid segment record")
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ErrSegmentChecksum = errors.New("segment checksum mismatch")
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ErrCommittedRangeMissing = errors.New("segment committed range is missing")
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ErrUnsafeSegmentReference = errors.New("unsafe segment reference")
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)
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type PayloadKind uint16
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const (
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PayloadKindExecutionSpec PayloadKind = 1
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PayloadKindCommandBlob PayloadKind = 2
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PayloadKindCommandEvent PayloadKind = 3
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PayloadKindStdin PayloadKind = 4
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PayloadKindAudit PayloadKind = 5
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)
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type SegmentRecord struct {
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OwnerUUID [16]byte
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Sequence uint64
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ObservedUnixNano int64
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ReceiptUnixNano int64
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Kind PayloadKind
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Stream uint16
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Compression uint16
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RawLength uint64
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Payload []byte
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}
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type SegmentLimits struct {
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MaxStoredBytes uint64
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MaxRawBytes uint64
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MaxRecordBytes uint64
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}
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func DefaultSegmentLimits() SegmentLimits {
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return SegmentLimits{MaxStoredBytes: DefaultSegmentLimit, MaxRawBytes: DefaultSegmentLimit, MaxRecordBytes: DefaultSegmentLimit + uint64(segmentHeaderSize) + segmentTrailerSize}
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}
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func EncodeSegmentRecord(record SegmentRecord, limits SegmentLimits) ([]byte, error) {
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if err := validateSegmentRecord(record, limits); err != nil {
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return nil, err
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}
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storedLength := uint64(len(record.Payload))
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recordLength := uint64(segmentHeaderSize) + storedLength + segmentTrailerSize
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header := make([]byte, segmentHeaderSize)
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copy(header[0:8], segmentMagic[:])
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binary.BigEndian.PutUint16(header[8:10], segmentVersion)
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binary.BigEndian.PutUint16(header[10:12], segmentHeaderSize)
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binary.BigEndian.PutUint64(header[12:20], recordLength)
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copy(header[20:36], record.OwnerUUID[:])
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binary.BigEndian.PutUint64(header[36:44], record.Sequence)
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binary.BigEndian.PutUint64(header[44:52], uint64(record.ObservedUnixNano))
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binary.BigEndian.PutUint64(header[52:60], uint64(record.ReceiptUnixNano))
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binary.BigEndian.PutUint16(header[60:62], uint16(record.Kind))
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binary.BigEndian.PutUint16(header[62:64], record.Stream)
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binary.BigEndian.PutUint16(header[64:66], record.Compression)
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binary.BigEndian.PutUint64(header[68:76], record.RawLength)
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binary.BigEndian.PutUint64(header[76:84], storedLength)
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payloadDigest := sha256Bytes(record.Payload)
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copy(header[84:116], payloadDigest[:])
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binary.BigEndian.PutUint32(header[headerCRCOffset:headerCRCOffset+4], crc32.Checksum(header, castagnoliTable))
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encoded := make([]byte, 0, recordLength)
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encoded = append(encoded, header...)
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encoded = append(encoded, record.Payload...)
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recordCRC := crc32.New(castagnoliTable)
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_, _ = recordCRC.Write(encoded)
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encoded = binary.BigEndian.AppendUint32(encoded, recordCRC.Sum32())
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return encoded, nil
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}
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func DecodeSegmentRecord(reader io.Reader, limits SegmentLimits) (SegmentRecord, uint64, error) {
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var record SegmentRecord
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header := make([]byte, segmentHeaderSize)
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if _, err := io.ReadFull(reader, header); err != nil {
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return record, 0, err
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}
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if !bytes.Equal(header[0:8], segmentMagic[:]) || binary.BigEndian.Uint16(header[8:10]) != segmentVersion || binary.BigEndian.Uint16(header[10:12]) != segmentHeaderSize {
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return record, 0, ErrInvalidSegmentRecord
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}
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wantHeaderCRC := binary.BigEndian.Uint32(header[headerCRCOffset : headerCRCOffset+4])
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headerForCRC := append([]byte(nil), header...)
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binary.BigEndian.PutUint32(headerForCRC[headerCRCOffset:headerCRCOffset+4], 0)
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if crc32.Checksum(headerForCRC, castagnoliTable) != wantHeaderCRC {
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return record, 0, ErrSegmentChecksum
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}
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if header[66] != 0 || header[67] != 0 || !allZero(header[120:128]) {
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return record, 0, ErrInvalidSegmentRecord
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}
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recordLength := binary.BigEndian.Uint64(header[12:20])
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storedLength := binary.BigEndian.Uint64(header[76:84])
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if err := validateEncodedLengths(storedLength, binary.BigEndian.Uint64(header[68:76]), recordLength, limits); err != nil {
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return record, 0, err
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}
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payload := make([]byte, int(storedLength))
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if _, err := io.ReadFull(reader, payload); err != nil {
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return record, 0, err
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}
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var trailer [segmentTrailerSize]byte
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if _, err := io.ReadFull(reader, trailer[:]); err != nil {
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return record, 0, err
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}
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recordCRC := crc32.New(castagnoliTable)
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_, _ = recordCRC.Write(header)
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_, _ = recordCRC.Write(payload)
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if recordCRC.Sum32() != binary.BigEndian.Uint32(trailer[:]) {
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return record, 0, ErrSegmentChecksum
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}
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wantDigest := header[84:116]
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gotDigest := sha256Bytes(payload)
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if !bytes.Equal(wantDigest, gotDigest[:]) {
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return record, 0, ErrSegmentChecksum
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}
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copy(record.OwnerUUID[:], header[20:36])
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record.Sequence = binary.BigEndian.Uint64(header[36:44])
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record.ObservedUnixNano = int64(binary.BigEndian.Uint64(header[44:52]))
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record.ReceiptUnixNano = int64(binary.BigEndian.Uint64(header[52:60]))
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record.Kind = PayloadKind(binary.BigEndian.Uint16(header[60:62]))
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record.Stream = binary.BigEndian.Uint16(header[62:64])
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record.Compression = binary.BigEndian.Uint16(header[64:66])
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record.RawLength = binary.BigEndian.Uint64(header[68:76])
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record.Payload = payload
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if err := validateSegmentRecord(record, limits); err != nil {
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return SegmentRecord{}, 0, err
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}
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return record, recordLength, nil
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}
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func validateSegmentRecord(record SegmentRecord, limits SegmentLimits) error {
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if err := validateLimits(limits); err != nil {
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return err
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}
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if record.Kind < PayloadKindExecutionSpec || record.Kind > PayloadKindAudit || record.Compression < 1 || record.Compression > 2 || record.Stream > 2 {
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return ErrInvalidSegmentRecord
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}
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if record.Kind != PayloadKindAudit && isZeroUUID(record.OwnerUUID) {
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return ErrInvalidSegmentRecord
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}
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if record.Kind == PayloadKindCommandEvent && record.Sequence == 0 {
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return ErrInvalidSegmentRecord
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}
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storedLength := uint64(len(record.Payload))
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recordLength := uint64(segmentHeaderSize) + storedLength + segmentTrailerSize
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if err := validateEncodedLengths(storedLength, record.RawLength, recordLength, limits); err != nil {
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return err
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}
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return validateStoredPayload(record, limits)
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}
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func validateStoredPayload(record SegmentRecord, limits SegmentLimits) error {
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if record.Compression == 1 {
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if record.RawLength != uint64(len(record.Payload)) {
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return ErrInvalidSegmentRecord
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}
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return nil
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}
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decoder, err := zstd.NewReader(bytes.NewReader(record.Payload), zstd.WithDecoderConcurrency(1), zstd.WithDecoderMaxMemory(limits.MaxRawBytes+1))
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if err != nil {
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return fmt.Errorf("%w: zstd header", ErrInvalidSegmentRecord)
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}
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defer decoder.Close()
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decodedBytes, err := io.Copy(io.Discard, io.LimitReader(decoder, int64(limits.MaxRawBytes)+1))
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if err != nil || uint64(decodedBytes) != record.RawLength || uint64(decodedBytes) > limits.MaxRawBytes {
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return fmt.Errorf("%w: zstd payload", ErrInvalidSegmentRecord)
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}
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return nil
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}
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func validateEncodedLengths(storedLength, rawLength, recordLength uint64, limits SegmentLimits) error {
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if err := validateLimits(limits); err != nil {
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return err
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}
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if storedLength > limits.MaxStoredBytes || rawLength > limits.MaxRawBytes || recordLength > limits.MaxRecordBytes {
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return ErrInvalidSegmentRecord
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}
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if storedLength > ^uint64(0)-uint64(segmentHeaderSize)-segmentTrailerSize || recordLength != uint64(segmentHeaderSize)+storedLength+segmentTrailerSize {
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return ErrInvalidSegmentRecord
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}
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return nil
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}
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func validateLimits(limits SegmentLimits) error {
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maxInt := uint64(^uint(0) >> 1)
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if limits.MaxStoredBytes == 0 || limits.MaxRawBytes == 0 || limits.MaxRecordBytes < uint64(segmentHeaderSize)+segmentTrailerSize || limits.MaxStoredBytes > maxInt || limits.MaxRawBytes >= maxInt || limits.MaxRecordBytes > maxInt {
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return ErrInvalidSegmentRecord
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}
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return nil
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}
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type Segment struct {
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mu sync.Mutex
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file *os.File
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name string
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offset uint64
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closed bool
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limits SegmentLimits
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}
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func CreateSegment(directory string, owner [16]byte, ordinal uint32, limits SegmentLimits) (*Segment, error) {
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if isZeroUUID(owner) {
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return nil, ErrUnsafeSegmentReference
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}
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if err := validateLimits(limits); err != nil {
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return nil, err
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}
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if err := ensurePrivateDirectory(directory); err != nil {
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return nil, err
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}
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name := hex.EncodeToString(owner[:]) + "-" + fmt.Sprintf("%010d", ordinal) + ".seg"
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path := filepath.Join(directory, name)
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file, err := os.OpenFile(path, os.O_CREATE|os.O_EXCL|os.O_RDWR, segmentFileMode)
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if err != nil {
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return nil, err
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}
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if err := file.Sync(); err != nil {
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_ = file.Close()
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return nil, err
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}
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if err := syncDirectory(directory); err != nil {
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_ = file.Close()
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return nil, err
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}
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return &Segment{file: file, name: name, limits: limits}, nil
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}
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func (segment *Segment) Name() string { return segment.name }
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func (segment *Segment) Append(record SegmentRecord) (uint64, error) {
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encoded, err := EncodeSegmentRecord(record, segment.limits)
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if err != nil {
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return 0, err
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}
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segment.mu.Lock()
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defer segment.mu.Unlock()
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if segment.closed {
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return 0, os.ErrClosed
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}
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if _, err := segment.file.WriteAt(encoded, int64(segment.offset)); err != nil {
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return 0, err
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}
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if err := segment.file.Sync(); err != nil {
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return 0, err
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}
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segment.offset += uint64(len(encoded))
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return segment.offset, nil
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}
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func (segment *Segment) Close() error {
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if segment == nil {
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return nil
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}
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segment.mu.Lock()
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defer segment.mu.Unlock()
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if segment.closed {
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return nil
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}
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segment.closed = true
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return segment.file.Close()
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}
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type SegmentRecovery struct {
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Records []SegmentRecord
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CommittedOffset uint64
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OriginalSize uint64
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TruncatedTail uint64
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}
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func RecoverSegment(directory, name string, committedOffset uint64, limits SegmentLimits) (SegmentRecovery, error) {
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var result SegmentRecovery
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if filepath.Base(name) != name {
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return result, ErrUnsafeSegmentReference
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}
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if _, _, err := parseSegmentName(name); err != nil {
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return result, err
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}
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if err := ensurePrivateDirectory(directory); err != nil {
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return result, err
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}
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path := filepath.Join(directory, name)
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info, err := os.Lstat(path)
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if err != nil {
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return result, err
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}
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if !info.Mode().IsRegular() || info.Mode()&os.ModeSymlink != 0 || info.Mode().Perm()&0o077 != 0 {
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return result, ErrUnsafeSegmentReference
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}
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result.OriginalSize = uint64(info.Size())
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result.CommittedOffset = committedOffset
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if result.OriginalSize < committedOffset {
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return result, ErrCommittedRangeMissing
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}
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file, err := os.OpenFile(path, os.O_RDWR, 0)
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if err != nil {
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return result, err
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}
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defer file.Close()
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limited := io.LimitReader(file, int64(committedOffset))
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var consumed uint64
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for consumed < committedOffset {
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record, length, err := DecodeSegmentRecord(limited, limits)
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if err != nil {
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return result, fmt.Errorf("decode committed record at offset %d: %w", consumed, err)
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}
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if length == 0 || length > committedOffset-consumed {
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return result, ErrCommittedRangeMissing
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}
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consumed += length
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result.Records = append(result.Records, record)
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}
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if consumed != committedOffset {
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return result, ErrCommittedRangeMissing
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}
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if result.OriginalSize > committedOffset {
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if err := file.Truncate(int64(committedOffset)); err != nil {
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return result, err
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}
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if err := file.Sync(); err != nil {
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return result, err
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}
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result.TruncatedTail = result.OriginalSize - committedOffset
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}
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return result, nil
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}
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func syncDirectory(path string) error {
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directory, err := os.Open(path)
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if err != nil {
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return err
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}
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defer directory.Close()
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return directory.Sync()
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}
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func isZeroUUID(value [16]byte) bool { return value == [16]byte{} }
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func allZero(value []byte) bool {
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for _, current := range value {
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if current != 0 {
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return false
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}
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}
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return true
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}
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func sha256Bytes(value []byte) [sha256.Size]byte { return sha256.Sum256(value) }
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func parseSegmentName(name string) ([16]byte, uint32, error) {
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var owner [16]byte
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if !segmentNamePattern.MatchString(name) {
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return owner, 0, ErrUnsafeSegmentReference
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}
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decoded, err := hex.DecodeString(name[:32])
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if err != nil {
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return owner, 0, ErrUnsafeSegmentReference
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}
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copy(owner[:], decoded)
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ordinal, err := strconv.ParseUint(name[33:43], 10, 32)
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if err != nil || isZeroUUID(owner) {
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return [16]byte{}, 0, ErrUnsafeSegmentReference
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}
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return owner, uint32(ordinal), nil
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}
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