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package internal
// NOTE: This is used from github.com/containers/image by callers that
// don't otherwise use containers/storage, so don't make this depend on any
// larger software like the graph drivers.
import (
"archive/tar"
"bytes"
"encoding/binary"
"fmt"
"io"
"time"
jsoniter "github.com/json-iterator/go"
"github.com/klauspost/compress/zstd"
"github.com/opencontainers/go-digest"
)
type TOC struct {
Version int `json:"version"`
Entries []FileMetadata `json:"entries"`
// internal: used by unmarshalToc
StringsBuf bytes.Buffer `json:"-"`
}
type FileMetadata struct {
Type string `json:"type"`
Name string `json:"name"`
Linkname string `json:"linkName,omitempty"`
Mode int64 `json:"mode,omitempty"`
Size int64 `json:"size,omitempty"`
UID int `json:"uid,omitempty"`
GID int `json:"gid,omitempty"`
ModTime *time.Time `json:"modtime,omitempty"`
AccessTime *time.Time `json:"accesstime,omitempty"`
ChangeTime *time.Time `json:"changetime,omitempty"`
Devmajor int64 `json:"devMajor,omitempty"`
Devminor int64 `json:"devMinor,omitempty"`
Xattrs map[string]string `json:"xattrs,omitempty"`
Digest string `json:"digest,omitempty"`
Offset int64 `json:"offset,omitempty"`
EndOffset int64 `json:"endOffset,omitempty"`
ChunkSize int64 `json:"chunkSize,omitempty"`
ChunkOffset int64 `json:"chunkOffset,omitempty"`
ChunkDigest string `json:"chunkDigest,omitempty"`
ChunkType string `json:"chunkType,omitempty"`
// internal: computed by mergeTOCEntries.
Chunks []*FileMetadata `json:"-"`
}
const (
ChunkTypeData = ""
ChunkTypeZeros = "zeros"
)
const (
TypeReg = "reg"
TypeChunk = "chunk"
TypeLink = "hardlink"
TypeChar = "char"
TypeBlock = "block"
TypeDir = "dir"
TypeFifo = "fifo"
TypeSymlink = "symlink"
)
var TarTypes = map[byte]string{
tar.TypeReg: TypeReg,
tar.TypeRegA: TypeReg,
tar.TypeLink: TypeLink,
tar.TypeChar: TypeChar,
tar.TypeBlock: TypeBlock,
tar.TypeDir: TypeDir,
tar.TypeFifo: TypeFifo,
tar.TypeSymlink: TypeSymlink,
}
func GetType(t byte) (string, error) {
r, found := TarTypes[t]
if !found {
return "", fmt.Errorf("unknown tarball type: %v", t)
}
return r, nil
}
const (
ManifestChecksumKey = "io.containers.zstd-chunked.manifest-checksum"
ManifestInfoKey = "io.containers.zstd-chunked.manifest-position"
// ManifestTypeCRFS is a manifest file compatible with the CRFS TOC file.
ManifestTypeCRFS = 1
// FooterSizeSupported is the footer size supported by this implementation.
// Newer versions of the image format might increase this value, so reject
// any version that is not supported.
FooterSizeSupported = 40
)
var (
// when the zstd decoder encounters a skippable frame + 1 byte for the size, it
// will ignore it.
// https://tools.ietf.org/html/rfc8478#section-3.1.2
skippableFrameMagic = []byte{0x50, 0x2a, 0x4d, 0x18}
ZstdChunkedFrameMagic = []byte{0x47, 0x6e, 0x55, 0x6c, 0x49, 0x6e, 0x55, 0x78}
)
func appendZstdSkippableFrame(dest io.Writer, data []byte) error {
if _, err := dest.Write(skippableFrameMagic); err != nil {
return err
}
var size []byte = make([]byte, 4)
binary.LittleEndian.PutUint32(size, uint32(len(data)))
if _, err := dest.Write(size); err != nil {
return err
}
if _, err := dest.Write(data); err != nil {
return err
}
return nil
}
func WriteZstdChunkedManifest(dest io.Writer, outMetadata map[string]string, offset uint64, metadata []FileMetadata, level int) error {
// 8 is the size of the zstd skippable frame header + the frame size
manifestOffset := offset + 8
toc := TOC{
Version: 1,
Entries: metadata,
}
var json = jsoniter.ConfigCompatibleWithStandardLibrary
// Generate the manifest
manifest, err := json.Marshal(toc)
if err != nil {
return err
}
var compressedBuffer bytes.Buffer
zstdWriter, err := ZstdWriterWithLevel(&compressedBuffer, level)
if err != nil {
return err
}
if _, err := zstdWriter.Write(manifest); err != nil {
zstdWriter.Close()
return err
}
if err := zstdWriter.Close(); err != nil {
return err
}
compressedManifest := compressedBuffer.Bytes()
manifestDigester := digest.Canonical.Digester()
manifestChecksum := manifestDigester.Hash()
if _, err := manifestChecksum.Write(compressedManifest); err != nil {
return err
}
outMetadata[ManifestChecksumKey] = manifestDigester.Digest().String()
outMetadata[ManifestInfoKey] = fmt.Sprintf("%d:%d:%d:%d", manifestOffset, len(compressedManifest), len(manifest), ManifestTypeCRFS)
if err := appendZstdSkippableFrame(dest, compressedManifest); err != nil {
return err
}
// Store the offset to the manifest and its size in LE order
var manifestDataLE []byte = make([]byte, FooterSizeSupported)
binary.LittleEndian.PutUint64(manifestDataLE, manifestOffset)
binary.LittleEndian.PutUint64(manifestDataLE[8:], uint64(len(compressedManifest)))
binary.LittleEndian.PutUint64(manifestDataLE[16:], uint64(len(manifest)))
binary.LittleEndian.PutUint64(manifestDataLE[24:], uint64(ManifestTypeCRFS))
copy(manifestDataLE[32:], ZstdChunkedFrameMagic)
return appendZstdSkippableFrame(dest, manifestDataLE)
}
func ZstdWriterWithLevel(dest io.Writer, level int) (*zstd.Encoder, error) {
el := zstd.EncoderLevelFromZstd(level)
return zstd.NewWriter(dest, zstd.WithEncoderLevel(el))
}
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