add functions/vendor files

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

@@ -0,0 +1,139 @@
+package digest
+
+import (
+	"fmt"
+	"hash"
+	"io"
+	"regexp"
+	"strings"
+)
+
+const (
+	// 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
+//
+// 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 Digest(fmt.Sprintf("%s:%x", alg, p))
+}
+
+// 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")
+
+	// 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")
+)
+
+// 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 using
+// the canonical digest algorithm.
+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)
+}
+
+// Validate checks that the contents of d is a valid digest, returning an
+// error if not.
+func (d Digest) Validate() error {
+	s := string(d)
+
+	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 := Algorithm(s[:i]); algorithm {
+	case SHA256, SHA384, SHA512:
+		if algorithm.Size()*2 != len(s[i+1:]) {
+			return ErrDigestInvalidLength
+		}
+		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
+}

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

@@ -0,0 +1,82 @@
+package digest
+
+import (
+	"testing"
+)
+
+func TestParseDigest(t *testing.T) {
+	for _, testcase := range []struct {
+		input     string
+		err       error
+		algorithm Algorithm
+		hex       string
+	}{
+		{
+			input:     "sha256:e58fcf7418d4390dec8e8fb69d88c06ec07039d651fedd3aa72af9972e7d046b",
+			algorithm: "sha256",
+			hex:       "e58fcf7418d4390dec8e8fb69d88c06ec07039d651fedd3aa72af9972e7d046b",
+		},
+		{
+			input:     "sha384:d3fc7881460b7e22e3d172954463dddd7866d17597e7248453c48b3e9d26d9596bf9c4a9cf8072c9d5bad76e19af801d",
+			algorithm: "sha384",
+			hex:       "d3fc7881460b7e22e3d172954463dddd7866d17597e7248453c48b3e9d26d9596bf9c4a9cf8072c9d5bad76e19af801d",
+		},
+		{
+			// empty hex
+			input: "sha256:",
+			err:   ErrDigestInvalidFormat,
+		},
+		{
+			// just hex
+			input: "d41d8cd98f00b204e9800998ecf8427e",
+			err:   ErrDigestInvalidFormat,
+		},
+		{
+			// not hex
+			input: "sha256:d41d8cd98f00b204e9800m98ecf8427e",
+			err:   ErrDigestInvalidFormat,
+		},
+		{
+			// too short
+			input: "sha256:abcdef0123456789",
+			err:   ErrDigestInvalidLength,
+		},
+		{
+			// too short (from different algorithm)
+			input: "sha512:abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789",
+			err:   ErrDigestInvalidLength,
+		},
+		{
+			input: "foo:d41d8cd98f00b204e9800998ecf8427e",
+			err:   ErrDigestUnsupported,
+		},
+	} {
+		digest, err := ParseDigest(testcase.input)
+		if err != testcase.err {
+			t.Fatalf("error differed from expected while parsing %q: %v != %v", testcase.input, err, testcase.err)
+		}
+
+		if testcase.err != nil {
+			continue
+		}
+
+		if digest.Algorithm() != testcase.algorithm {
+			t.Fatalf("incorrect algorithm for parsed digest: %q != %q", digest.Algorithm(), testcase.algorithm)
+		}
+
+		if digest.Hex() != testcase.hex {
+			t.Fatalf("incorrect hex for parsed digest: %q != %q", digest.Hex(), testcase.hex)
+		}
+
+		// Parse string return value and check equality
+		newParsed, err := ParseDigest(digest.String())
+
+		if err != nil {
+			t.Fatalf("unexpected error parsing input %q: %v", testcase.input, err)
+		}
+
+		if newParsed != digest {
+			t.Fatalf("expected equal: %q != %q", newParsed, digest)
+		}
+	}
+}

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

@@ -0,0 +1,155 @@
+package digest
+
+import (
+	"crypto"
+	"fmt"
+	"hash"
+	"io"
+)
+
+// Algorithm identifies and implementation of a digester by an identifier.
+// Note the that this defines both the hash algorithm used and the string
+// encoding.
+type Algorithm string
+
+// supported digest types
+const (
+	SHA256 Algorithm = "sha256" // sha256 with hex encoding
+	SHA384 Algorithm = "sha384" // sha384 with hex encoding
+	SHA512 Algorithm = "sha512" // sha512 with hex encoding
+
+	// Canonical is the primary digest algorithm used with the distribution
+	// project. Other digests may be used but this one is the primary storage
+	// digest.
+	Canonical = SHA256
+)
+
+var (
+	// TODO(stevvooe): Follow the pattern of the standard crypto package for
+	// registration of digests. Effectively, we are a registerable set and
+	// common symbol access.
+
+	// algorithms maps values to hash.Hash implementations. Other algorithms
+	// may be available but they cannot be calculated by the digest package.
+	algorithms = map[Algorithm]crypto.Hash{
+		SHA256: crypto.SHA256,
+		SHA384: crypto.SHA384,
+		SHA512: crypto.SHA512,
+	}
+)
+
+// Available returns true if the digest type is available for use. If this
+// returns false, New and Hash will return nil.
+func (a Algorithm) Available() bool {
+	h, ok := algorithms[a]
+	if !ok {
+		return false
+	}
+
+	// check availability of the hash, as well
+	return h.Available()
+}
+
+func (a Algorithm) String() string {
+	return string(a)
+}
+
+// Size returns number of bytes returned by the hash.
+func (a Algorithm) Size() int {
+	h, ok := algorithms[a]
+	if !ok {
+		return 0
+	}
+	return h.Size()
+}
+
+// Set implemented to allow use of Algorithm as a command line flag.
+func (a *Algorithm) Set(value string) error {
+	if value == "" {
+		*a = Canonical
+	} else {
+		// just do a type conversion, support is queried with Available.
+		*a = Algorithm(value)
+	}
+
+	return nil
+}
+
+// New returns a new digester for the specified algorithm. If the algorithm
+// does not have a digester implementation, nil will be returned. This can be
+// checked by calling Available before calling New.
+func (a Algorithm) New() Digester {
+	return &digester{
+		alg:  a,
+		hash: a.Hash(),
+	}
+}
+
+// Hash returns a new hash as used by the algorithm. If not available, the
+// method will panic. Check Algorithm.Available() before calling.
+func (a Algorithm) Hash() hash.Hash {
+	if !a.Available() {
+		// NOTE(stevvooe): A missing hash is usually a programming error that
+		// must be resolved at compile time. We don't import in the digest
+		// package to allow users to choose their hash implementation (such as
+		// when using stevvooe/resumable or a hardware accelerated package).
+		//
+		// Applications that may want to resolve the hash at runtime should
+		// call Algorithm.Available before call Algorithm.Hash().
+		panic(fmt.Sprintf("%v not available (make sure it is imported)", a))
+	}
+
+	return algorithms[a].New()
+}
+
+// FromReader returns the digest of the reader using the algorithm.
+func (a Algorithm) FromReader(rd io.Reader) (Digest, error) {
+	digester := a.New()
+
+	if _, err := io.Copy(digester.Hash(), rd); err != nil {
+		return "", err
+	}
+
+	return digester.Digest(), nil
+}
+
+// FromBytes digests the input and returns a Digest.
+func (a Algorithm) FromBytes(p []byte) Digest {
+	digester := a.New()
+
+	if _, err := digester.Hash().Write(p); err != nil {
+		// Writes to a Hash should never fail. None of the existing
+		// hash implementations in the stdlib or hashes vendored
+		// here can return errors from Write. Having a panic in this
+		// condition instead of having FromBytes return an error value
+		// avoids unnecessary error handling paths in all callers.
+		panic("write to hash function returned error: " + err.Error())
+	}
+
+	return digester.Digest()
+}
+
+// TODO(stevvooe): Allow resolution of verifiers using the digest type and
+// this registration system.
+
+// Digester calculates the digest of written data. Writes should go directly
+// to the return value of Hash, while calling Digest will return the current
+// value of the digest.
+type Digester interface {
+	Hash() hash.Hash // provides direct access to underlying hash instance.
+	Digest() Digest
+}
+
+// digester provides a simple digester definition that embeds a hasher.
+type digester struct {
+	alg  Algorithm
+	hash hash.Hash
+}
+
+func (d *digester) Hash() hash.Hash {
+	return d.hash
+}
+
+func (d *digester) Digest() Digest {
+	return NewDigest(d.alg, d.hash)
+}

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

@@ -0,0 +1,21 @@
+// +build !noresumabledigest
+
+package digest
+
+import (
+	"testing"
+
+	"github.com/stevvooe/resumable"
+	_ "github.com/stevvooe/resumable/sha256"
+)
+
+// TestResumableDetection just ensures that the resumable capability of a hash
+// is exposed through the digester type, which is just a hash plus a Digest
+// method.
+func TestResumableDetection(t *testing.T) {
+	d := Canonical.New()
+
+	if _, ok := d.Hash().(resumable.Hash); !ok {
+		t.Fatalf("expected digester to implement resumable.Hash: %#v, %v", d, d.Hash())
+	}
+}

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

@@ -0,0 +1,42 @@
+// Package digest provides a generalized type to opaquely represent message
+// digests and their operations within the registry. The Digest type is
+// designed to serve as a flexible identifier in a content-addressable system.
+// More importantly, it provides tools and wrappers to work with
+// hash.Hash-based digests with little effort.
+//
+// Basics
+//
+// The format of a digest is simply a string with two parts, dubbed the
+// "algorithm" and the "digest", separated by a colon:
+//
+// 	<algorithm>:<digest>
+//
+// An example of a sha256 digest representation follows:
+//
+// 	sha256:7173b809ca12ec5dee4506cd86be934c4596dd234ee82c0662eac04a8c2c71dc
+//
+// In this case, the string "sha256" is the algorithm and the hex bytes are
+// the "digest".
+//
+// Because the Digest type is simply a string, once a valid Digest is
+// obtained, comparisons are cheap, quick and simple to express with the
+// standard equality operator.
+//
+// Verification
+//
+// The main benefit of using the Digest type is simple verification against a
+// given digest. The Verifier interface, modeled after the stdlib hash.Hash
+// interface, provides a common write sink for digest verification. After
+// writing is complete, calling the Verifier.Verified method will indicate
+// whether or not the stream of bytes matches the target digest.
+//
+// Missing Features
+//
+// In addition to the above, we intend to add the following features to this
+// package:
+//
+// 1. A Digester type that supports write sink digest calculation.
+//
+// 2. Suspend and resume of ongoing digest calculations to support efficient digest verification in the registry.
+//
+package digest

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

@@ -0,0 +1,245 @@
+package digest
+
+import (
+	"errors"
+	"sort"
+	"strings"
+	"sync"
+)
+
+var (
+	// ErrDigestNotFound is used when a matching digest
+	// could not be found in a set.
+	ErrDigestNotFound = errors.New("digest not found")
+
+	// ErrDigestAmbiguous is used when multiple digests
+	// are found in a set. None of the matching digests
+	// should be considered valid matches.
+	ErrDigestAmbiguous = errors.New("ambiguous digest string")
+)
+
+// Set is used to hold a unique set of digests which
+// may be easily referenced by easily  referenced by a string
+// representation of the digest as well as short representation.
+// The uniqueness of the short representation is based on other
+// digests in the set. If digests are omitted from this set,
+// collisions in a larger set may not be detected, therefore it
+// is important to always do short representation lookups on
+// the complete set of digests. To mitigate collisions, an
+// appropriately long short code should be used.
+type Set struct {
+	mutex   sync.RWMutex
+	entries digestEntries
+}
+
+// NewSet creates an empty set of digests
+// which may have digests added.
+func NewSet() *Set {
+	return &Set{
+		entries: digestEntries{},
+	}
+}
+
+// checkShortMatch checks whether two digests match as either whole
+// values or short values. This function does not test equality,
+// rather whether the second value could match against the first
+// value.
+func checkShortMatch(alg Algorithm, hex, shortAlg, shortHex string) bool {
+	if len(hex) == len(shortHex) {
+		if hex != shortHex {
+			return false
+		}
+		if len(shortAlg) > 0 && string(alg) != shortAlg {
+			return false
+		}
+	} else if !strings.HasPrefix(hex, shortHex) {
+		return false
+	} else if len(shortAlg) > 0 && string(alg) != shortAlg {
+		return false
+	}
+	return true
+}
+
+// Lookup looks for a digest matching the given string representation.
+// If no digests could be found ErrDigestNotFound will be returned
+// with an empty digest value. If multiple matches are found
+// ErrDigestAmbiguous will be returned with an empty digest value.
+func (dst *Set) Lookup(d string) (Digest, error) {
+	dst.mutex.RLock()
+	defer dst.mutex.RUnlock()
+	if len(dst.entries) == 0 {
+		return "", ErrDigestNotFound
+	}
+	var (
+		searchFunc func(int) bool
+		alg        Algorithm
+		hex        string
+	)
+	dgst, err := ParseDigest(d)
+	if err == ErrDigestInvalidFormat {
+		hex = d
+		searchFunc = func(i int) bool {
+			return dst.entries[i].val >= d
+		}
+	} else {
+		hex = dgst.Hex()
+		alg = dgst.Algorithm()
+		searchFunc = func(i int) bool {
+			if dst.entries[i].val == hex {
+				return dst.entries[i].alg >= alg
+			}
+			return dst.entries[i].val >= hex
+		}
+	}
+	idx := sort.Search(len(dst.entries), searchFunc)
+	if idx == len(dst.entries) || !checkShortMatch(dst.entries[idx].alg, dst.entries[idx].val, string(alg), hex) {
+		return "", ErrDigestNotFound
+	}
+	if dst.entries[idx].alg == alg && dst.entries[idx].val == hex {
+		return dst.entries[idx].digest, nil
+	}
+	if idx+1 < len(dst.entries) && checkShortMatch(dst.entries[idx+1].alg, dst.entries[idx+1].val, string(alg), hex) {
+		return "", ErrDigestAmbiguous
+	}
+
+	return dst.entries[idx].digest, nil
+}
+
+// Add adds the given digest to the set. An error will be returned
+// if the given digest is invalid. If the digest already exists in the
+// set, this operation will be a no-op.
+func (dst *Set) Add(d Digest) error {
+	if err := d.Validate(); err != nil {
+		return err
+	}
+	dst.mutex.Lock()
+	defer dst.mutex.Unlock()
+	entry := &digestEntry{alg: d.Algorithm(), val: d.Hex(), digest: d}
+	searchFunc := func(i int) bool {
+		if dst.entries[i].val == entry.val {
+			return dst.entries[i].alg >= entry.alg
+		}
+		return dst.entries[i].val >= entry.val
+	}
+	idx := sort.Search(len(dst.entries), searchFunc)
+	if idx == len(dst.entries) {
+		dst.entries = append(dst.entries, entry)
+		return nil
+	} else if dst.entries[idx].digest == d {
+		return nil
+	}
+
+	entries := append(dst.entries, nil)
+	copy(entries[idx+1:], entries[idx:len(entries)-1])
+	entries[idx] = entry
+	dst.entries = entries
+	return nil
+}
+
+// Remove removes the given digest from the set. An err will be
+// returned if the given digest is invalid. If the digest does
+// not exist in the set, this operation will be a no-op.
+func (dst *Set) Remove(d Digest) error {
+	if err := d.Validate(); err != nil {
+		return err
+	}
+	dst.mutex.Lock()
+	defer dst.mutex.Unlock()
+	entry := &digestEntry{alg: d.Algorithm(), val: d.Hex(), digest: d}
+	searchFunc := func(i int) bool {
+		if dst.entries[i].val == entry.val {
+			return dst.entries[i].alg >= entry.alg
+		}
+		return dst.entries[i].val >= entry.val
+	}
+	idx := sort.Search(len(dst.entries), searchFunc)
+	// Not found if idx is after or value at idx is not digest
+	if idx == len(dst.entries) || dst.entries[idx].digest != d {
+		return nil
+	}
+
+	entries := dst.entries
+	copy(entries[idx:], entries[idx+1:])
+	entries = entries[:len(entries)-1]
+	dst.entries = entries
+
+	return nil
+}
+
+// All returns all the digests in the set
+func (dst *Set) All() []Digest {
+	dst.mutex.RLock()
+	defer dst.mutex.RUnlock()
+	retValues := make([]Digest, len(dst.entries))
+	for i := range dst.entries {
+		retValues[i] = dst.entries[i].digest
+	}
+
+	return retValues
+}
+
+// ShortCodeTable returns a map of Digest to unique short codes. The
+// length represents the minimum value, the maximum length may be the
+// entire value of digest if uniqueness cannot be achieved without the
+// full value. This function will attempt to make short codes as short
+// as possible to be unique.
+func ShortCodeTable(dst *Set, length int) map[Digest]string {
+	dst.mutex.RLock()
+	defer dst.mutex.RUnlock()
+	m := make(map[Digest]string, len(dst.entries))
+	l := length
+	resetIdx := 0
+	for i := 0; i < len(dst.entries); i++ {
+		var short string
+		extended := true
+		for extended {
+			extended = false
+			if len(dst.entries[i].val) <= l {
+				short = dst.entries[i].digest.String()
+			} else {
+				short = dst.entries[i].val[:l]
+				for j := i + 1; j < len(dst.entries); j++ {
+					if checkShortMatch(dst.entries[j].alg, dst.entries[j].val, "", short) {
+						if j > resetIdx {
+							resetIdx = j
+						}
+						extended = true
+					} else {
+						break
+					}
+				}
+				if extended {
+					l++
+				}
+			}
+		}
+		m[dst.entries[i].digest] = short
+		if i >= resetIdx {
+			l = length
+		}
+	}
+	return m
+}
+
+type digestEntry struct {
+	alg    Algorithm
+	val    string
+	digest Digest
+}
+
+type digestEntries []*digestEntry
+
+func (d digestEntries) Len() int {
+	return len(d)
+}
+
+func (d digestEntries) Less(i, j int) bool {
+	if d[i].val != d[j].val {
+		return d[i].val < d[j].val
+	}
+	return d[i].alg < d[j].alg
+}
+
+func (d digestEntries) Swap(i, j int) {
+	d[i], d[j] = d[j], d[i]
+}

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

@@ -0,0 +1,368 @@
+package digest
+
+import (
+	"crypto/sha256"
+	"encoding/binary"
+	"math/rand"
+	"testing"
+)
+
+func assertEqualDigests(t *testing.T, d1, d2 Digest) {
+	if d1 != d2 {
+		t.Fatalf("Digests do not match:\n\tActual: %s\n\tExpected: %s", d1, d2)
+	}
+}
+
+func TestLookup(t *testing.T) {
+	digests := []Digest{
+		"sha256:1234511111111111111111111111111111111111111111111111111111111111",
+		"sha256:1234111111111111111111111111111111111111111111111111111111111111",
+		"sha256:1234611111111111111111111111111111111111111111111111111111111111",
+		"sha256:5432111111111111111111111111111111111111111111111111111111111111",
+		"sha256:6543111111111111111111111111111111111111111111111111111111111111",
+		"sha256:6432111111111111111111111111111111111111111111111111111111111111",
+		"sha256:6542111111111111111111111111111111111111111111111111111111111111",
+		"sha256:6532111111111111111111111111111111111111111111111111111111111111",
+	}
+
+	dset := NewSet()
+	for i := range digests {
+		if err := dset.Add(digests[i]); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	dgst, err := dset.Lookup("54")
+	if err != nil {
+		t.Fatal(err)
+	}
+	assertEqualDigests(t, dgst, digests[3])
+
+	dgst, err = dset.Lookup("1234")
+	if err == nil {
+		t.Fatal("Expected ambiguous error looking up: 1234")
+	}
+	if err != ErrDigestAmbiguous {
+		t.Fatal(err)
+	}
+
+	dgst, err = dset.Lookup("9876")
+	if err == nil {
+		t.Fatal("Expected ambiguous error looking up: 9876")
+	}
+	if err != ErrDigestNotFound {
+		t.Fatal(err)
+	}
+
+	dgst, err = dset.Lookup("sha256:1234")
+	if err == nil {
+		t.Fatal("Expected ambiguous error looking up: sha256:1234")
+	}
+	if err != ErrDigestAmbiguous {
+		t.Fatal(err)
+	}
+
+	dgst, err = dset.Lookup("sha256:12345")
+	if err != nil {
+		t.Fatal(err)
+	}
+	assertEqualDigests(t, dgst, digests[0])
+
+	dgst, err = dset.Lookup("sha256:12346")
+	if err != nil {
+		t.Fatal(err)
+	}
+	assertEqualDigests(t, dgst, digests[2])
+
+	dgst, err = dset.Lookup("12346")
+	if err != nil {
+		t.Fatal(err)
+	}
+	assertEqualDigests(t, dgst, digests[2])
+
+	dgst, err = dset.Lookup("12345")
+	if err != nil {
+		t.Fatal(err)
+	}
+	assertEqualDigests(t, dgst, digests[0])
+}
+
+func TestAddDuplication(t *testing.T) {
+	digests := []Digest{
+		"sha256:1234111111111111111111111111111111111111111111111111111111111111",
+		"sha256:1234511111111111111111111111111111111111111111111111111111111111",
+		"sha256:1234611111111111111111111111111111111111111111111111111111111111",
+		"sha256:5432111111111111111111111111111111111111111111111111111111111111",
+		"sha256:6543111111111111111111111111111111111111111111111111111111111111",
+		"sha512:65431111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111",
+		"sha512:65421111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111",
+		"sha512:65321111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111",
+	}
+
+	dset := NewSet()
+	for i := range digests {
+		if err := dset.Add(digests[i]); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	if len(dset.entries) != 8 {
+		t.Fatal("Invalid dset size")
+	}
+
+	if err := dset.Add(Digest("sha256:1234511111111111111111111111111111111111111111111111111111111111")); err != nil {
+		t.Fatal(err)
+	}
+
+	if len(dset.entries) != 8 {
+		t.Fatal("Duplicate digest insert allowed")
+	}
+
+	if err := dset.Add(Digest("sha384:123451111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111")); err != nil {
+		t.Fatal(err)
+	}
+
+	if len(dset.entries) != 9 {
+		t.Fatal("Insert with different algorithm not allowed")
+	}
+}
+
+func TestRemove(t *testing.T) {
+	digests, err := createDigests(10)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	dset := NewSet()
+	for i := range digests {
+		if err := dset.Add(digests[i]); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	dgst, err := dset.Lookup(digests[0].String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if dgst != digests[0] {
+		t.Fatalf("Unexpected digest value:\n\tExpected: %s\n\tActual: %s", digests[0], dgst)
+	}
+
+	if err := dset.Remove(digests[0]); err != nil {
+		t.Fatal(err)
+	}
+
+	if _, err := dset.Lookup(digests[0].String()); err != ErrDigestNotFound {
+		t.Fatalf("Expected error %v when looking up removed digest, got %v", ErrDigestNotFound, err)
+	}
+}
+
+func TestAll(t *testing.T) {
+	digests, err := createDigests(100)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	dset := NewSet()
+	for i := range digests {
+		if err := dset.Add(digests[i]); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	all := map[Digest]struct{}{}
+	for _, dgst := range dset.All() {
+		all[dgst] = struct{}{}
+	}
+
+	if len(all) != len(digests) {
+		t.Fatalf("Unexpected number of unique digests found:\n\tExpected: %d\n\tActual: %d", len(digests), len(all))
+	}
+
+	for i, dgst := range digests {
+		if _, ok := all[dgst]; !ok {
+			t.Fatalf("Missing element at position %d: %s", i, dgst)
+		}
+	}
+
+}
+
+func assertEqualShort(t *testing.T, actual, expected string) {
+	if actual != expected {
+		t.Fatalf("Unexpected short value:\n\tExpected: %s\n\tActual: %s", expected, actual)
+	}
+}
+
+func TestShortCodeTable(t *testing.T) {
+	digests := []Digest{
+		"sha256:1234111111111111111111111111111111111111111111111111111111111111",
+		"sha256:1234511111111111111111111111111111111111111111111111111111111111",
+		"sha256:1234611111111111111111111111111111111111111111111111111111111111",
+		"sha256:5432111111111111111111111111111111111111111111111111111111111111",
+		"sha256:6543111111111111111111111111111111111111111111111111111111111111",
+		"sha256:6432111111111111111111111111111111111111111111111111111111111111",
+		"sha256:6542111111111111111111111111111111111111111111111111111111111111",
+		"sha256:6532111111111111111111111111111111111111111111111111111111111111",
+	}
+
+	dset := NewSet()
+	for i := range digests {
+		if err := dset.Add(digests[i]); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	dump := ShortCodeTable(dset, 2)
+
+	if len(dump) < len(digests) {
+		t.Fatalf("Error unexpected size: %d, expecting %d", len(dump), len(digests))
+	}
+	assertEqualShort(t, dump[digests[0]], "12341")
+	assertEqualShort(t, dump[digests[1]], "12345")
+	assertEqualShort(t, dump[digests[2]], "12346")
+	assertEqualShort(t, dump[digests[3]], "54")
+	assertEqualShort(t, dump[digests[4]], "6543")
+	assertEqualShort(t, dump[digests[5]], "64")
+	assertEqualShort(t, dump[digests[6]], "6542")
+	assertEqualShort(t, dump[digests[7]], "653")
+}
+
+func createDigests(count int) ([]Digest, error) {
+	r := rand.New(rand.NewSource(25823))
+	digests := make([]Digest, count)
+	for i := range digests {
+		h := sha256.New()
+		if err := binary.Write(h, binary.BigEndian, r.Int63()); err != nil {
+			return nil, err
+		}
+		digests[i] = NewDigest("sha256", h)
+	}
+	return digests, nil
+}
+
+func benchAddNTable(b *testing.B, n int) {
+	digests, err := createDigests(n)
+	if err != nil {
+		b.Fatal(err)
+	}
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		dset := &Set{entries: digestEntries(make([]*digestEntry, 0, n))}
+		for j := range digests {
+			if err = dset.Add(digests[j]); err != nil {
+				b.Fatal(err)
+			}
+		}
+	}
+}
+
+func benchLookupNTable(b *testing.B, n int, shortLen int) {
+	digests, err := createDigests(n)
+	if err != nil {
+		b.Fatal(err)
+	}
+	dset := &Set{entries: digestEntries(make([]*digestEntry, 0, n))}
+	for i := range digests {
+		if err := dset.Add(digests[i]); err != nil {
+			b.Fatal(err)
+		}
+	}
+	shorts := make([]string, 0, n)
+	for _, short := range ShortCodeTable(dset, shortLen) {
+		shorts = append(shorts, short)
+	}
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		if _, err = dset.Lookup(shorts[i%n]); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func benchRemoveNTable(b *testing.B, n int) {
+	digests, err := createDigests(n)
+	if err != nil {
+		b.Fatal(err)
+	}
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		dset := &Set{entries: digestEntries(make([]*digestEntry, 0, n))}
+		b.StopTimer()
+		for j := range digests {
+			if err = dset.Add(digests[j]); err != nil {
+				b.Fatal(err)
+			}
+		}
+		b.StartTimer()
+		for j := range digests {
+			if err = dset.Remove(digests[j]); err != nil {
+				b.Fatal(err)
+			}
+		}
+	}
+}
+
+func benchShortCodeNTable(b *testing.B, n int, shortLen int) {
+	digests, err := createDigests(n)
+	if err != nil {
+		b.Fatal(err)
+	}
+	dset := &Set{entries: digestEntries(make([]*digestEntry, 0, n))}
+	for i := range digests {
+		if err := dset.Add(digests[i]); err != nil {
+			b.Fatal(err)
+		}
+	}
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		ShortCodeTable(dset, shortLen)
+	}
+}
+
+func BenchmarkAdd10(b *testing.B) {
+	benchAddNTable(b, 10)
+}
+
+func BenchmarkAdd100(b *testing.B) {
+	benchAddNTable(b, 100)
+}
+
+func BenchmarkAdd1000(b *testing.B) {
+	benchAddNTable(b, 1000)
+}
+
+func BenchmarkRemove10(b *testing.B) {
+	benchRemoveNTable(b, 10)
+}
+
+func BenchmarkRemove100(b *testing.B) {
+	benchRemoveNTable(b, 100)
+}
+
+func BenchmarkRemove1000(b *testing.B) {
+	benchRemoveNTable(b, 1000)
+}
+
+func BenchmarkLookup10(b *testing.B) {
+	benchLookupNTable(b, 10, 12)
+}
+
+func BenchmarkLookup100(b *testing.B) {
+	benchLookupNTable(b, 100, 12)
+}
+
+func BenchmarkLookup1000(b *testing.B) {
+	benchLookupNTable(b, 1000, 12)
+}
+
+func BenchmarkShortCode10(b *testing.B) {
+	benchShortCodeNTable(b, 10, 12)
+}
+func BenchmarkShortCode100(b *testing.B) {
+	benchShortCodeNTable(b, 100, 12)
+}
+func BenchmarkShortCode1000(b *testing.B) {
+	benchShortCodeNTable(b, 1000, 12)
+}

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

@@ -0,0 +1,44 @@
+package digest
+
+import (
+	"hash"
+	"io"
+)
+
+// Verifier presents a general verification interface to be used with message
+// digests and other byte stream verifications. Users instantiate a Verifier
+// from one of the various methods, write the data under test to it then check
+// the result with the Verified method.
+type Verifier interface {
+	io.Writer
+
+	// Verified will return true if the content written to Verifier matches
+	// the digest.
+	Verified() bool
+}
+
+// NewDigestVerifier returns a verifier that compares the written bytes
+// against a passed in digest.
+func NewDigestVerifier(d Digest) (Verifier, error) {
+	if err := d.Validate(); err != nil {
+		return nil, err
+	}
+
+	return hashVerifier{
+		hash:   d.Algorithm().Hash(),
+		digest: d,
+	}, nil
+}
+
+type hashVerifier struct {
+	digest Digest
+	hash   hash.Hash
+}
+
+func (hv hashVerifier) Write(p []byte) (n int, err error) {
+	return hv.hash.Write(p)
+}
+
+func (hv hashVerifier) Verified() bool {
+	return hv.digest == NewDigest(hv.digest.Algorithm(), hv.hash)
+}

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

@@ -0,0 +1,49 @@
+package digest
+
+import (
+	"bytes"
+	"crypto/rand"
+	"io"
+	"testing"
+)
+
+func TestDigestVerifier(t *testing.T) {
+	p := make([]byte, 1<<20)
+	rand.Read(p)
+	digest := FromBytes(p)
+
+	verifier, err := NewDigestVerifier(digest)
+	if err != nil {
+		t.Fatalf("unexpected error getting digest verifier: %s", err)
+	}
+
+	io.Copy(verifier, bytes.NewReader(p))
+
+	if !verifier.Verified() {
+		t.Fatalf("bytes not verified")
+	}
+}
+
+// TestVerifierUnsupportedDigest ensures that unsupported digest validation is
+// flowing through verifier creation.
+func TestVerifierUnsupportedDigest(t *testing.T) {
+	unsupported := Digest("bean:0123456789abcdef")
+
+	_, err := NewDigestVerifier(unsupported)
+	if err == nil {
+		t.Fatalf("expected error when creating verifier")
+	}
+
+	if err != ErrDigestUnsupported {
+		t.Fatalf("incorrect error for unsupported digest: %v", err)
+	}
+}
+
+// TODO(stevvooe): Add benchmarks to measure bytes/second throughput for
+// DigestVerifier.
+//
+// The relevant benchmark for comparison can be run with the following
+// commands:
+//
+// 	go test -bench . crypto/sha1
+//