move dependencies to vendor

vendor/github.com/docker/distribution/digest/digest.go

@@ -0,0 +1,168 @@
+package digest
+
+import (
+	"bytes"
+	"fmt"
+	"hash"
+	"io"
+	"io/ioutil"
+	"regexp"
+	"strings"
+
+	"github.com/docker/docker/pkg/tarsum"
+)
+
+const (
+	// DigestTarSumV1EmptyTar is the digest for the empty tar file.
+	DigestTarSumV1EmptyTar = "tarsum.v1+sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+
+	// DigestSha256EmptyTar is the canonical sha256 digest of empty data
+	DigestSha256EmptyTar = "sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+)
+
+// Digest allows simple protection of hex formatted digest strings, prefixed
+// by their algorithm. Strings of type Digest have some guarantee of being in
+// the correct format and it provides quick access to the components of a
+// digest string.
+//
+// The following is an example of the contents of Digest types:
+//
+// 	sha256:7173b809ca12ec5dee4506cd86be934c4596dd234ee82c0662eac04a8c2c71dc
+//
+// More important for this code base, this type is compatible with tarsum
+// digests. For example, the following would be a valid Digest:
+//
+// 	tarsum+sha256:e58fcf7418d4390dec8e8fb69d88c06ec07039d651fedd3aa72af9972e7d046b
+//
+// This allows to abstract the digest behind this type and work only in those
+// terms.
+type Digest string
+
+// NewDigest returns a Digest from alg and a hash.Hash object.
+func NewDigest(alg Algorithm, h hash.Hash) Digest {
+	return Digest(fmt.Sprintf("%s:%x", alg, h.Sum(nil)))
+}
+
+// NewDigestFromHex returns a Digest from alg and a the hex encoded digest.
+func NewDigestFromHex(alg, hex string) Digest {
+	return Digest(fmt.Sprintf("%s:%s", alg, hex))
+}
+
+// DigestRegexp matches valid digest types.
+var DigestRegexp = regexp.MustCompile(`[a-zA-Z0-9-_+.]+:[a-fA-F0-9]+`)
+
+// DigestRegexpAnchored matches valid digest types, anchored to the start and end of the match.
+var DigestRegexpAnchored = regexp.MustCompile(`^` + DigestRegexp.String() + `$`)
+
+var (
+	// ErrDigestInvalidFormat returned when digest format invalid.
+	ErrDigestInvalidFormat = fmt.Errorf("invalid checksum digest format")
+
+	// ErrDigestUnsupported returned when the digest algorithm is unsupported.
+	ErrDigestUnsupported = fmt.Errorf("unsupported digest algorithm")
+)
+
+// ParseDigest parses s and returns the validated digest object. An error will
+// be returned if the format is invalid.
+func ParseDigest(s string) (Digest, error) {
+	d := Digest(s)
+
+	return d, d.Validate()
+}
+
+// FromReader returns the most valid digest for the underlying content.
+func FromReader(rd io.Reader) (Digest, error) {
+	digester := Canonical.New()
+
+	if _, err := io.Copy(digester.Hash(), rd); err != nil {
+		return "", err
+	}
+
+	return digester.Digest(), nil
+}
+
+// FromTarArchive produces a tarsum digest from reader rd.
+func FromTarArchive(rd io.Reader) (Digest, error) {
+	ts, err := tarsum.NewTarSum(rd, true, tarsum.Version1)
+	if err != nil {
+		return "", err
+	}
+
+	if _, err := io.Copy(ioutil.Discard, ts); err != nil {
+		return "", err
+	}
+
+	d, err := ParseDigest(ts.Sum(nil))
+	if err != nil {
+		return "", err
+	}
+
+	return d, nil
+}
+
+// FromBytes digests the input and returns a Digest.
+func FromBytes(p []byte) (Digest, error) {
+	return FromReader(bytes.NewReader(p))
+}
+
+// Validate checks that the contents of d is a valid digest, returning an
+// error if not.
+func (d Digest) Validate() error {
+	s := string(d)
+	// Common case will be tarsum
+	_, err := ParseTarSum(s)
+	if err == nil {
+		return nil
+	}
+
+	// Continue on for general parser
+
+	if !DigestRegexpAnchored.MatchString(s) {
+		return ErrDigestInvalidFormat
+	}
+
+	i := strings.Index(s, ":")
+	if i < 0 {
+		return ErrDigestInvalidFormat
+	}
+
+	// case: "sha256:" with no hex.
+	if i+1 == len(s) {
+		return ErrDigestInvalidFormat
+	}
+
+	switch Algorithm(s[:i]) {
+	case SHA256, SHA384, SHA512:
+		break
+	default:
+		return ErrDigestUnsupported
+	}
+
+	return nil
+}
+
+// Algorithm returns the algorithm portion of the digest. This will panic if
+// the underlying digest is not in a valid format.
+func (d Digest) Algorithm() Algorithm {
+	return Algorithm(d[:d.sepIndex()])
+}
+
+// Hex returns the hex digest portion of the digest. This will panic if the
+// underlying digest is not in a valid format.
+func (d Digest) Hex() string {
+	return string(d[d.sepIndex()+1:])
+}
+
+func (d Digest) String() string {
+	return string(d)
+}
+
+func (d Digest) sepIndex() int {
+	i := strings.Index(string(d), ":")
+
+	if i < 0 {
+		panic("could not find ':' in digest: " + d)
+	}
+
+	return i
+}