Initial

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

vendor/github.com/opencontainers/go-digest/digest.go

@@ -0,0 +1,156 @@
+// Copyright 2017 Docker, Inc.
+//
+// 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
+//
+//     https://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 digest
+
+import (
+	"fmt"
+	"hash"
+	"io"
+	"regexp"
+	"strings"
+)
+
+// 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
+//
+// 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 NewDigestFromBytes(alg, h.Sum(nil))
+}
+
+// NewDigestFromBytes returns a new digest from the byte contents of p.
+// Typically, this can come from hash.Hash.Sum(...) or xxx.SumXXX(...)
+// functions. This is also useful for rebuilding digests from binary
+// serializations.
+func NewDigestFromBytes(alg Algorithm, p []byte) Digest {
+	return NewDigestFromEncoded(alg, alg.Encode(p))
+}
+
+// NewDigestFromHex is deprecated. Please use NewDigestFromEncoded.
+func NewDigestFromHex(alg, hex string) Digest {
+	return NewDigestFromEncoded(Algorithm(alg), hex)
+}
+
+// NewDigestFromEncoded returns a Digest from alg and the encoded digest.
+func NewDigestFromEncoded(alg Algorithm, encoded string) Digest {
+	return Digest(fmt.Sprintf("%s:%s", alg, encoded))
+}
+
+// DigestRegexp matches valid digest types.
+var DigestRegexp = regexp.MustCompile(`[a-z0-9]+(?:[.+_-][a-z0-9]+)*:[a-zA-Z0-9=_-]+`)
+
+// 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")
+
+	// ErrDigestInvalidLength returned when digest has invalid length.
+	ErrDigestInvalidLength = fmt.Errorf("invalid checksum digest length")
+
+	// ErrDigestUnsupported returned when the digest algorithm is unsupported.
+	ErrDigestUnsupported = fmt.Errorf("unsupported digest algorithm")
+)
+
+// Parse parses s and returns the validated digest object. An error will
+// be returned if the format is invalid.
+func Parse(s string) (Digest, error) {
+	d := Digest(s)
+	return d, d.Validate()
+}
+
+// FromReader consumes the content of rd until io.EOF, returning canonical digest.
+func FromReader(rd io.Reader) (Digest, error) {
+	return Canonical.FromReader(rd)
+}
+
+// FromBytes digests the input and returns a Digest.
+func FromBytes(p []byte) Digest {
+	return Canonical.FromBytes(p)
+}
+
+// FromString digests the input and returns a Digest.
+func FromString(s string) Digest {
+	return Canonical.FromString(s)
+}
+
+// Validate checks that the contents of d is a valid digest, returning an
+// error if not.
+func (d Digest) Validate() error {
+	s := string(d)
+	i := strings.Index(s, ":")
+	if i <= 0 || i+1 == len(s) {
+		return ErrDigestInvalidFormat
+	}
+	algorithm, encoded := Algorithm(s[:i]), s[i+1:]
+	if !algorithm.Available() {
+		if !DigestRegexpAnchored.MatchString(s) {
+			return ErrDigestInvalidFormat
+		}
+		return ErrDigestUnsupported
+	}
+	return algorithm.Validate(encoded)
+}
+
+// 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()])
+}
+
+// Verifier returns a writer object that can be used to verify a stream of
+// content against the digest. If the digest is invalid, the method will panic.
+func (d Digest) Verifier() Verifier {
+	return hashVerifier{
+		hash:   d.Algorithm().Hash(),
+		digest: d,
+	}
+}
+
+// Encoded returns the encoded portion of the digest. This will panic if the
+// underlying digest is not in a valid format.
+func (d Digest) Encoded() string {
+	return string(d[d.sepIndex()+1:])
+}
+
+// Hex is deprecated. Please use Digest.Encoded.
+func (d Digest) Hex() string {
+	return d.Encoded()
+}
+
+func (d Digest) String() string {
+	return string(d)
+}
+
+func (d Digest) sepIndex() int {
+	i := strings.Index(string(d), ":")
+
+	if i < 0 {
+		panic(fmt.Sprintf("no ':' separator in digest %q", d))
+	}
+
+	return i
+}