1 files changed, 216 insertions, 0 deletions
diff --git a/vendor/github.com/containerd/stargz-snapshotter/estargz/gzip.go b/vendor/github.com/containerd/stargz-snapshotter/estargz/gzip.go
new file mode 100644
index 000000000..efc435e09
--- /dev/null
+++ b/vendor/github.com/containerd/stargz-snapshotter/estargz/gzip.go
@@ -0,0 +1,216 @@
+/*
+   Copyright The containerd Authors.
+
+   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.
+*/
+
+/*
+   Copyright 2019 The Go Authors. All rights reserved.
+   Use of this source code is governed by a BSD-style
+   license that can be found in the LICENSE file.
+*/
+
+package estargz
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"encoding/binary"
+	"encoding/json"
+	"fmt"
+	"hash"
+	"io"
+	"strconv"
+
+	digest "github.com/opencontainers/go-digest"
+	"github.com/pkg/errors"
+)
+
+type gzipCompression struct {
+	*gzipCompressor
+	*GzipDecompressor
+}
+
+func newGzipCompressionWithLevel(level int) Compression {
+	return &gzipCompression{
+		&gzipCompressor{level},
+		&GzipDecompressor{},
+	}
+}
+
+func NewGzipCompressorWithLevel(level int) Compressor {
+	return &gzipCompressor{level}
+}
+
+type gzipCompressor struct {
+	compressionLevel int
+}
+
+func (gc *gzipCompressor) Writer(w io.Writer) (io.WriteCloser, error) {
+	return gzip.NewWriterLevel(w, gc.compressionLevel)
+}
+
+func (gc *gzipCompressor) WriteTOCAndFooter(w io.Writer, off int64, toc *JTOC, diffHash hash.Hash) (digest.Digest, error) {
+	tocJSON, err := json.MarshalIndent(toc, "", "\t")
+	if err != nil {
+		return "", err
+	}
+	gz, _ := gzip.NewWriterLevel(w, gc.compressionLevel)
+	gw := io.Writer(gz)
+	if diffHash != nil {
+		gw = io.MultiWriter(gz, diffHash)
+	}
+	tw := tar.NewWriter(gw)
+	if err := tw.WriteHeader(&tar.Header{
+		Typeflag: tar.TypeReg,
+		Name:     TOCTarName,
+		Size:     int64(len(tocJSON)),
+	}); err != nil {
+		return "", err
+	}
+	if _, err := tw.Write(tocJSON); err != nil {
+		return "", err
+	}
+
+	if err := tw.Close(); err != nil {
+		return "", err
+	}
+	if err := gz.Close(); err != nil {
+		return "", err
+	}
+	if _, err := w.Write(gzipFooterBytes(off)); err != nil {
+		return "", err
+	}
+	return digest.FromBytes(tocJSON), nil
+}
+
+// gzipFooterBytes returns the 51 bytes footer.
+func gzipFooterBytes(tocOff int64) []byte {
+	buf := bytes.NewBuffer(make([]byte, 0, FooterSize))
+	gz, _ := gzip.NewWriterLevel(buf, gzip.NoCompression) // MUST be NoCompression to keep 51 bytes
+
+	// Extra header indicating the offset of TOCJSON
+	// https://tools.ietf.org/html/rfc1952#section-2.3.1.1
+	header := make([]byte, 4)
+	header[0], header[1] = 'S', 'G'
+	subfield := fmt.Sprintf("%016xSTARGZ", tocOff)
+	binary.LittleEndian.PutUint16(header[2:4], uint16(len(subfield))) // little-endian per RFC1952
+	gz.Header.Extra = append(header, []byte(subfield)...)
+	gz.Close()
+	if buf.Len() != FooterSize {
+		panic(fmt.Sprintf("footer buffer = %d, not %d", buf.Len(), FooterSize))
+	}
+	return buf.Bytes()
+}
+
+type GzipDecompressor struct{}
+
+func (gz *GzipDecompressor) Reader(r io.Reader) (io.ReadCloser, error) {
+	return gzip.NewReader(r)
+}
+
+func (gz *GzipDecompressor) ParseTOC(r io.Reader) (toc *JTOC, tocDgst digest.Digest, err error) {
+	return parseTOCEStargz(r)
+}
+
+func (gz *GzipDecompressor) ParseFooter(p []byte) (tocOffset, tocSize int64, err error) {
+	if len(p) != FooterSize {
+		return 0, 0, fmt.Errorf("invalid length %d cannot be parsed", len(p))
+	}
+	zr, err := gzip.NewReader(bytes.NewReader(p))
+	if err != nil {
+		return 0, 0, err
+	}
+	defer zr.Close()
+	extra := zr.Header.Extra
+	si1, si2, subfieldlen, subfield := extra[0], extra[1], extra[2:4], extra[4:]
+	if si1 != 'S' || si2 != 'G' {
+		return 0, 0, fmt.Errorf("invalid subfield IDs: %q, %q; want E, S", si1, si2)
+	}
+	if slen := binary.LittleEndian.Uint16(subfieldlen); slen != uint16(16+len("STARGZ")) {
+		return 0, 0, fmt.Errorf("invalid length of subfield %d; want %d", slen, 16+len("STARGZ"))
+	}
+	if string(subfield[16:]) != "STARGZ" {
+		return 0, 0, fmt.Errorf("STARGZ magic string must be included in the footer subfield")
+	}
+	tocOffset, err = strconv.ParseInt(string(subfield[:16]), 16, 64)
+	if err != nil {
+		return 0, 0, errors.Wrapf(err, "legacy: failed to parse toc offset")
+	}
+	return tocOffset, 0, nil
+}
+
+func (gz *GzipDecompressor) FooterSize() int64 {
+	return FooterSize
+}
+
+type legacyGzipDecompressor struct{}
+
+func (gz *legacyGzipDecompressor) Reader(r io.Reader) (io.ReadCloser, error) {
+	return gzip.NewReader(r)
+}
+
+func (gz *legacyGzipDecompressor) ParseTOC(r io.Reader) (toc *JTOC, tocDgst digest.Digest, err error) {
+	return parseTOCEStargz(r)
+}
+
+func (gz *legacyGzipDecompressor) ParseFooter(p []byte) (tocOffset, tocSize int64, err error) {
+	if len(p) != legacyFooterSize {
+		return 0, 0, fmt.Errorf("legacy: invalid length %d cannot be parsed", len(p))
+	}
+	zr, err := gzip.NewReader(bytes.NewReader(p))
+	if err != nil {
+		return 0, 0, errors.Wrapf(err, "legacy: failed to get footer gzip reader")
+	}
+	defer zr.Close()
+	extra := zr.Header.Extra
+	if len(extra) != 16+len("STARGZ") {
+		return 0, 0, fmt.Errorf("legacy: invalid stargz's extra field size")
+	}
+	if string(extra[16:]) != "STARGZ" {
+		return 0, 0, fmt.Errorf("legacy: magic string STARGZ not found")
+	}
+	tocOffset, err = strconv.ParseInt(string(extra[:16]), 16, 64)
+	if err != nil {
+		return 0, 0, errors.Wrapf(err, "legacy: failed to parse toc offset")
+	}
+	return tocOffset, 0, nil
+}
+
+func (gz *legacyGzipDecompressor) FooterSize() int64 {
+	return legacyFooterSize
+}
+
+func parseTOCEStargz(r io.Reader) (toc *JTOC, tocDgst digest.Digest, err error) {
+	zr, err := gzip.NewReader(r)
+	if err != nil {
+		return nil, "", fmt.Errorf("malformed TOC gzip header: %v", err)
+	}
+	defer zr.Close()
+	zr.Multistream(false)
+	tr := tar.NewReader(zr)
+	h, err := tr.Next()
+	if err != nil {
+		return nil, "", fmt.Errorf("failed to find tar header in TOC gzip stream: %v", err)
+	}
+	if h.Name != TOCTarName {
+		return nil, "", fmt.Errorf("TOC tar entry had name %q; expected %q", h.Name, TOCTarName)
+	}
+	dgstr := digest.Canonical.Digester()
+	toc = new(JTOC)
+	if err := json.NewDecoder(io.TeeReader(tr, dgstr.Hash())).Decode(&toc); err != nil {
+		return nil, "", fmt.Errorf("error decoding TOC JSON: %v", err)
+	}
+	return toc, dgstr.Digest(), nil
+}