gx publish 0.7.13

Readme/golint: improve readme with gx instructions. Make golint happy.

.gitignore

@@ -0,0 +1 @@
+cid-fuzz.zip

.gx/lastpubver

@@ -1 +1 @@
-0.5.1: QmUrECr5NauzkUaofvUnCFGjZ4Wevt76n79uv6BhEkuyn3
+0.7.13: QmZe3S3sXMWar3oPmrd8jHV8NoAWfPfLGFD8PsK3YrYpqv

.travis.yml

@@ -0,0 +1,24 @@
+os:
+  - linux
+  - osx
+
+language: go
+
+go:
+    - 1.7
+
+install: true
+
+before_install:
+  - make deps
+
+script:
+  - go vet
+  - $GOPATH/bin/goveralls -service="travis-ci"
+
+cache:
+    directories:
+        - $GOPATH/src/gx
+
+notifications:
+  email: false

LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2016 Protocol Labs, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

Makefile

@@ -0,0 +1,16 @@
+all: deps
+
+gx:
+	go get github.com/whyrusleeping/gx
+	go get github.com/whyrusleeping/gx-go
+
+covertools:
+	go get github.com/mattn/goveralls
+	go get golang.org/x/tools/cmd/cover
+
+deps: gx covertools
+	gx --verbose install --global
+	gx-go rewrite
+
+publish:
+	gx-go rewrite --undo

README.md

@@ -0,0 +1,125 @@
+go-cid
+==================
+
+[![](https://img.shields.io/badge/made%20by-Protocol%20Labs-blue.svg?style=flat-square)](http://ipn.io)
+[![](https://img.shields.io/badge/project-IPFS-blue.svg?style=flat-square)](http://ipfs.io/)
+[![](https://img.shields.io/badge/freenode-%23ipfs-blue.svg?style=flat-square)](http://webchat.freenode.net/?channels=%23ipfs)
+[![](https://img.shields.io/badge/readme%20style-standard-brightgreen.svg?style=flat-square)](https://github.com/RichardLitt/standard-readme)
+[![GoDoc](https://godoc.org/github.com/ipfs/go-cid?status.svg)](https://godoc.org/github.com/ipfs/go-cid)
+[![Coverage Status](https://coveralls.io/repos/github/ipfs/go-cid/badge.svg?branch=master)](https://coveralls.io/github/ipfs/go-cid?branch=master)
+[![Travis CI](https://travis-ci.org/ipfs/go-cid.svg?branch=master)](https://travis-ci.org/ipfs/go-cid)
+
+> A package to handle content IDs in Go.
+
+This is an implementation in Go of the [CID spec](https://github.com/ipld/cid).
+It is used in `go-ipfs` and related packages to refer to a typed hunk of data.
+
+
+## Table of Contents
+
+- [Install](#install)
+- [Usage](#usage)
+- [API](#api)
+- [Contribute](#contribute)
+- [License](#license)
+
+## Install
+
+`go-cid` is a standard Go module which can be installed with:
+
+```sh
+go get github.com/ipfs/go-cid
+```
+
+Note that `go-cid` is packaged with Gx, so it is recommended to use Gx to install and use it (see Usage section).
+
+## Usage
+
+### Using Gx and Gx-go
+
+This module is packaged with [Gx](https://github.com/whyrusleeping/gx). In order to use it in your own project it is recommended that you:
+
+```sh
+go get -u github.com/whyrusleeping/gx
+go get -u github.com/whyrusleeping/gx-go
+cd <your-project-repository>
+gx init
+gx import github.com/ipfs/go-cid
+gx install --global
+gx-go --rewrite
+```
+
+Please check [Gx](https://github.com/whyrusleeping/gx) and [Gx-go](https://github.com/whyrusleeping/gx-go) documentation for more information.
+
+### Running tests
+
+Before running tests, please run:
+
+```sh
+make deps
+```
+
+This will make sure that dependencies are rewritten to known working versions.
+
+### Examples
+
+#### Parsing string input from users
+
+```go
+// Create a cid from a marshaled string
+c, err := cid.Decode("zdvgqEMYmNeH5fKciougvQcfzMcNjF3Z1tPouJ8C7pc3pe63k")
+if err != nil {...}
+
+fmt.Println("Got CID: ", c)
+```
+
+#### Creating a CID from scratch
+
+```go
+// Create a cid manually by specifying the 'prefix' parameters
+pref := cid.Prefix{
+	Version: 1,
+	Codec: cid.Raw,
+	MhType: mh.SHA2_256,
+	MhLength: -1, // default length
+}
+
+// And then feed it some data
+c, err := pref.Sum([]byte("Hello World!"))
+if err != nil {...}
+
+fmt.Println("Created CID: ", c)
+```
+
+#### Check if two CIDs match
+
+```go
+// To test if two cid's are equivalent, be sure to use the 'Equals' method:
+if c1.Equals(c2) {
+	fmt.Println("These two refer to the same exact data!")
+}
+```
+
+#### Check if some data matches a given CID
+
+```go
+// To check if some data matches a given cid, 
+// Get your CIDs prefix, and use that to sum the data in question:
+other, err := c.Prefix().Sum(mydata)
+if err != nil {...}
+
+if !c.Equals(other) {
+	fmt.Println("This data is different.")
+}
+
+```
+
+## Contribute
+
+PRs are welcome!
+
+Small note: If editing the Readme, please conform to the [standard-readme](https://github.com/RichardLitt/standard-readme) specification.
+
+## License
+
+MIT © Jeromy Johnson

cid.go

@@ -1,46 +1,146 @@
+// Package cid implements the Content-IDentifiers specification
+// (https://github.com/ipld/cid) in Go. CIDs are
+// self-describing content-addressed identifiers useful for
+// distributed information systems. CIDs are used in the IPFS
+// (https://ipfs.io) project ecosystem.
+//
+// CIDs have two major versions. A CIDv0 corresponds to a multihash of type
+// DagProtobuf, is deprecated and exists for compatibility reasons. Usually,
+// CIDv1 should be used.
+//
+// A CIDv1 has four parts:
+//
+//     <cidv1> ::= <multibase-prefix><cid-version><multicodec-packed-content-type><multihash-content-address>
+//
+// As shown above, the CID implementation relies heavily on Multiformats,
+// particularly Multibase
+// (https://github.com/multiformats/go-multibase), Multicodec
+// (https://github.com/multiformats/multicodec) and Multihash
+// implementations (https://github.com/multiformats/go-multihash).
 package cid
 
 import (
 	"bytes"
 	"encoding/binary"
+	"encoding/json"
+	"errors"
 	"fmt"
+	"strings"
 
-	mh "github.com/jbenet/go-multihash"
 	mbase "github.com/multiformats/go-multibase"
+	mh "github.com/multiformats/go-multihash"
 )
 
+// UnsupportedVersionString just holds an error message
 const UnsupportedVersionString = "<unsupported cid version>"
 
-const (
-	Protobuf = 0x70
-	CBOR     = 0x71
-	Raw      = 0x72
-	JSON     = 0x73
+var (
+	// ErrVarintBuffSmall means that a buffer passed to the cid parser was not
+	// long enough, or did not contain an invalid cid
+	ErrVarintBuffSmall = errors.New("reading varint: buffer too small")
+
+	// ErrVarintTooBig means that the varint in the given cid was above the
+	// limit of 2^64
+	ErrVarintTooBig = errors.New("reading varint: varint bigger than 64bits" +
+		" and not supported")
+
+	// ErrCidTooShort means that the cid passed to decode was not long
+	// enough to be a valid Cid
+	ErrCidTooShort = errors.New("cid too short")
 )
 
-func NewCidV0(h mh.Multihash) *Cid {
+// These are multicodec-packed content types. The should match
+// the codes described in the authoritative document:
+// https://github.com/multiformats/multicodec/blob/master/table.csv
+const (
+	Raw = 0x55
+
+	DagProtobuf = 0x70
+	DagCBOR     = 0x71
+
+	EthBlock           = 0x90
+	EthBlockList       = 0x91
+	EthTxTrie          = 0x92
+	EthTx              = 0x93
+	EthTxReceiptTrie   = 0x94
+	EthTxReceipt       = 0x95
+	EthStateTrie       = 0x96
+	EthAccountSnapshot = 0x97
+	EthStorageTrie     = 0x98
+	BitcoinBlock       = 0xb0
+	BitcoinTx          = 0xb1
+	ZcashBlock         = 0xc0
+	ZcashTx            = 0xc1
+)
+
+// NewCidV0 returns a Cid-wrapped multihash.
+// They exist to allow IPFS to work with Cids while keeping
+// compatibility with the plain-multihash format used used in IPFS.
+// NewCidV1 should be used preferentially.
+func NewCidV0(mhash mh.Multihash) *Cid {
 	return &Cid{
 		version: 0,
-		codec:   Protobuf,
-		hash:    h,
+		codec:   DagProtobuf,
+		hash:    mhash,
 	}
 }
 
-func NewCidV1(c uint64, h mh.Multihash) *Cid {
+// NewCidV1 returns a new Cid using the given multicodec-packed
+// content type.
+func NewCidV1(codecType uint64, mhash mh.Multihash) *Cid {
 	return &Cid{
 		version: 1,
-		codec:   c,
-		hash:    h,
+		codec:   codecType,
+		hash:    mhash,
 	}
 }
 
+// Cid represents a self-describing content adressed
+// identifier. It is formed by a Version, a Codec (which indicates
+// a multicodec-packed content type) and a Multihash.
 type Cid struct {
 	version uint64
 	codec   uint64
 	hash    mh.Multihash
 }
 
+// Parse is a short-hand function to perform Decode, Cast etc... on
+// a generic interface{} type.
+func Parse(v interface{}) (*Cid, error) {
+	switch v2 := v.(type) {
+	case string:
+		if strings.Contains(v2, "/ipfs/") {
+			return Decode(strings.Split(v2, "/ipfs/")[1])
+		}
+		return Decode(v2)
+	case []byte:
+		return Cast(v2)
+	case mh.Multihash:
+		return NewCidV0(v2), nil
+	case *Cid:
+		return v2, nil
+	default:
+		return nil, fmt.Errorf("can't parse %+v as Cid", v2)
+	}
+}
+
+// Decode parses a Cid-encoded string and returns a Cid object.
+// For CidV1, a Cid-encoded string is primarily a multibase string:
+//
+//     <multibase-type-code><base-encoded-string>
+//
+// The base-encoded string represents a:
+//
+// <version><codec-type><multihash>
+//
+// Decode will also detect and parse CidV0 strings. Strings
+// starting with "Qm" are considered CidV0 and treated directly
+// as B58-encoded multihashes.
 func Decode(v string) (*Cid, error) {
+	if len(v) < 2 {
+		return nil, ErrCidTooShort
+	}
+
 	if len(v) == 46 && v[:2] == "Qm" {
 		hash, err := mh.FromB58String(v)
 		if err != nil {
@@ -58,6 +158,28 @@ func Decode(v string) (*Cid, error) {
 	return Cast(data)
 }
 
+func uvError(read int) error {
+	switch {
+	case read == 0:
+		return ErrVarintBuffSmall
+	case read < 0:
+		return ErrVarintTooBig
+	default:
+		return nil
+	}
+}
+
+// Cast takes a Cid data slice, parses it and returns a Cid.
+// For CidV1, the data buffer is in the form:
+//
+//     <version><codec-type><multihash>
+//
+// CidV0 are also supported. In particular, data buffers starting
+// with length 34 bytes, which starts with bytes [18,32...] are considered
+// binary multihashes.
+//
+// Please use decode when parsing a regular Cid string, as Cast does not
+// expect multibase-encoded data. Cast accepts the output of Cid.Bytes().
 func Cast(data []byte) (*Cid, error) {
 	if len(data) == 34 && data[0] == 18 && data[1] == 32 {
 		h, err := mh.Cast(data)
@@ -66,18 +188,25 @@ func Cast(data []byte) (*Cid, error) {
 		}
 
 		return &Cid{
-			codec:   Protobuf,
+			codec:   DagProtobuf,
 			version: 0,
 			hash:    h,
 		}, nil
 	}
 
 	vers, n := binary.Uvarint(data)
+	if err := uvError(n); err != nil {
+		return nil, err
+	}
+
 	if vers != 0 && vers != 1 {
 		return nil, fmt.Errorf("invalid cid version number: %d", vers)
 	}
 
 	codec, cn := binary.Uvarint(data[n:])
+	if err := uvError(cn); err != nil {
+		return nil, err
+	}
 
 	rest := data[n+cn:]
 	h, err := mh.Cast(rest)
@@ -92,10 +221,14 @@ func Cast(data []byte) (*Cid, error) {
 	}, nil
 }
 
+// Type returns the multicodec-packed content type of a Cid.
 func (c *Cid) Type() uint64 {
 	return c.codec
 }
 
+// String returns the default string representation of a
+// Cid. Currently, Base58 is used as the encoding for the
+// multibase string.
 func (c *Cid) String() string {
 	switch c.version {
 	case 0:
@@ -112,10 +245,14 @@ func (c *Cid) String() string {
 	}
 }
 
+// Hash returns the multihash contained by a Cid.
 func (c *Cid) Hash() mh.Multihash {
 	return c.hash
 }
 
+// Bytes returns the byte representation of a Cid.
+// The output of bytes can be parsed back into a Cid
+// with Cast().
 func (c *Cid) Bytes() []byte {
 	switch c.version {
 	case 0:
@@ -132,25 +269,45 @@ func (c *Cid) bytesV0() []byte {
 }
 
 func (c *Cid) bytesV1() []byte {
-	buf := make([]byte, 8+len(c.hash))
+	// two 8 bytes (max) numbers plus hash
+	buf := make([]byte, 2*binary.MaxVarintLen64+len(c.hash))
 	n := binary.PutUvarint(buf, c.version)
 	n += binary.PutUvarint(buf[n:], c.codec)
-	copy(buf[n:], c.hash)
+	cn := copy(buf[n:], c.hash)
+	if cn != len(c.hash) {
+		panic("copy hash length is inconsistent")
+	}
 
 	return buf[:n+len(c.hash)]
 }
 
+// Equals checks that two Cids are the same.
+// In order for two Cids to be considered equal, the
+// Version, the Codec and the Multihash must match.
 func (c *Cid) Equals(o *Cid) bool {
 	return c.codec == o.codec &&
 		c.version == o.version &&
 		bytes.Equal(c.hash, o.hash)
 }
 
+// UnmarshalJSON parses the JSON representation of a Cid.
 func (c *Cid) UnmarshalJSON(b []byte) error {
 	if len(b) < 2 {
 		return fmt.Errorf("invalid cid json blob")
 	}
-	out, err := Decode(string(b[1 : len(b)-1]))
+	obj := struct {
+		CidTarget string `json:"/"`
+	}{}
+	err := json.Unmarshal(b, &obj)
+	if err != nil {
+		return err
+	}
+
+	if obj.CidTarget == "" {
+		return fmt.Errorf("cid was incorrectly formatted")
+	}
+
+	out, err := Decode(obj.CidTarget)
 	if err != nil {
 		return err
 	}
@@ -161,16 +318,109 @@ func (c *Cid) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
+// MarshalJSON procudes a JSON representation of a Cid, which looks as follows:
+//
+//    { "/": "<cid-string>" }
+//
+// Note that this formatting comes from the IPLD specification
+// (https://github.com/ipld/specs/tree/master/ipld)
 func (c *Cid) MarshalJSON() ([]byte, error) {
-	return []byte(fmt.Sprintf("\"%s\"", c.String())), nil
+	return []byte(fmt.Sprintf("{\"/\":\"%s\"}", c.String())), nil
 }
 
+// KeyString casts the result of cid.Bytes() as a string, and returns it.
 func (c *Cid) KeyString() string {
 	return string(c.Bytes())
 }
 
+// Loggable returns a Loggable (as defined by
+// https://godoc.org/github.com/ipfs/go-log).
 func (c *Cid) Loggable() map[string]interface{} {
 	return map[string]interface{}{
 		"cid": c,
 	}
 }
+
+// Prefix builds and returns a Prefix out of a Cid.
+func (c *Cid) Prefix() Prefix {
+	dec, _ := mh.Decode(c.hash) // assuming we got a valid multiaddr, this will not error
+	return Prefix{
+		MhType:   dec.Code,
+		MhLength: dec.Length,
+		Version:  c.version,
+		Codec:    c.codec,
+	}
+}
+
+// Prefix represents all the metadata of a Cid,
+// that is, the Version, the Codec, the Multihash type
+// and the Multihash length. It does not contains
+// any actual content information.
+type Prefix struct {
+	Version  uint64
+	Codec    uint64
+	MhType   uint64
+	MhLength int
+}
+
+// Sum uses the information in a prefix to perform a multihash.Sum()
+// and return a newly constructed Cid with the resulting multihash.
+func (p Prefix) Sum(data []byte) (*Cid, error) {
+	hash, err := mh.Sum(data, p.MhType, p.MhLength)
+	if err != nil {
+		return nil, err
+	}
+
+	switch p.Version {
+	case 0:
+		return NewCidV0(hash), nil
+	case 1:
+		return NewCidV1(p.Codec, hash), nil
+	default:
+		return nil, fmt.Errorf("invalid cid version")
+	}
+}
+
+// Bytes returns a byte representation of a Prefix. It looks like:
+//
+//     <version><codec><mh-type><mh-length>
+func (p Prefix) Bytes() []byte {
+	buf := make([]byte, 4*binary.MaxVarintLen64)
+	n := binary.PutUvarint(buf, p.Version)
+	n += binary.PutUvarint(buf[n:], p.Codec)
+	n += binary.PutUvarint(buf[n:], uint64(p.MhType))
+	n += binary.PutUvarint(buf[n:], uint64(p.MhLength))
+	return buf[:n]
+}
+
+// PrefixFromBytes parses a Prefix-byte representation onto a
+// Prefix.
+func PrefixFromBytes(buf []byte) (Prefix, error) {
+	r := bytes.NewReader(buf)
+	vers, err := binary.ReadUvarint(r)
+	if err != nil {
+		return Prefix{}, err
+	}
+
+	codec, err := binary.ReadUvarint(r)
+	if err != nil {
+		return Prefix{}, err
+	}
+
+	mhtype, err := binary.ReadUvarint(r)
+	if err != nil {
+		return Prefix{}, err
+	}
+
+	mhlen, err := binary.ReadUvarint(r)
+	if err != nil {
+		return Prefix{}, err
+	}
+
+	return Prefix{
+		Version:  vers,
+		Codec:    codec,
+		MhType:   mhtype,
+		MhLength: int(mhlen),
+	}, nil
+}

cid_fuzz.go

@@ -0,0 +1,37 @@
+// +build gofuzz
+
+package cid
+
+func Fuzz(data []byte) int {
+	cid, err := Cast(data)
+
+	if err != nil {
+		return 0
+	}
+
+	_ = cid.Bytes()
+	_ = cid.String()
+	p := cid.Prefix()
+	_ = p.Bytes()
+
+	if !cid.Equals(cid) {
+		panic("inequality")
+	}
+
+	// json loop
+	json, err := cid.MarshalJSON()
+	if err != nil {
+		panic(err.Error())
+	}
+	cid2 := &Cid{}
+	err = cid2.UnmarshalJSON(json)
+	if err != nil {
+		panic(err.Error())
+	}
+
+	if !cid.Equals(cid2) {
+		panic("json loop not equal")
+	}
+
+	return 1
+}

cid_test.go

@@ -2,9 +2,13 @@ package cid
 
 import (
 	"bytes"
+	"encoding/json"
+	"fmt"
+	"math/rand"
+	"strings"
 	"testing"
 
-	mh "github.com/jbenet/go-multihash"
+	mh "github.com/multiformats/go-multihash"
 )
 
 func assertEqual(t *testing.T, a, b *Cid) {
@@ -51,6 +55,13 @@ func TestBasicMarshaling(t *testing.T) {
 	assertEqual(t, cid, out2)
 }
 
+func TestEmptyString(t *testing.T) {
+	_, err := Decode("")
+	if err == nil {
+		t.Fatal("shouldnt be able to parse an empty cid")
+	}
+}
+
 func TestV0Handling(t *testing.T) {
 	old := "QmdfTbBqBPQ7VNxZEYEj14VmRuZBkqFbiwReogJgS1zR1n"
 
@@ -79,3 +90,140 @@ func TestV0ErrorCases(t *testing.T) {
 		t.Fatal("should have failed to decode that ref")
 	}
 }
+
+func TestPrefixRoundtrip(t *testing.T) {
+	data := []byte("this is some test content")
+	hash, _ := mh.Sum(data, mh.SHA2_256, -1)
+	c := NewCidV1(DagCBOR, hash)
+
+	pref := c.Prefix()
+
+	c2, err := pref.Sum(data)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !c.Equals(c2) {
+		t.Fatal("output didnt match original")
+	}
+
+	pb := pref.Bytes()
+
+	pref2, err := PrefixFromBytes(pb)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if pref.Version != pref2.Version || pref.Codec != pref2.Codec ||
+		pref.MhType != pref2.MhType || pref.MhLength != pref2.MhLength {
+		t.Fatal("input prefix didnt match output")
+	}
+}
+
+func Test16BytesVarint(t *testing.T) {
+	data := []byte("this is some test content")
+	hash, _ := mh.Sum(data, mh.SHA2_256, -1)
+	c := NewCidV1(DagCBOR, hash)
+
+	c.codec = 1 << 63
+	_ = c.Bytes()
+}
+
+func TestFuzzCid(t *testing.T) {
+	buf := make([]byte, 128)
+	for i := 0; i < 200; i++ {
+		s := rand.Intn(128)
+		rand.Read(buf[:s])
+		_, _ = Cast(buf[:s])
+	}
+}
+
+func TestParse(t *testing.T) {
+	cid, err := Parse(123)
+	if err == nil {
+		t.Fatalf("expected error from Parse()")
+	}
+	if !strings.Contains(err.Error(), "can't parse 123 as Cid") {
+		t.Fatalf("expected int error, got %s", err.Error())
+	}
+
+	theHash := "QmdfTbBqBPQ7VNxZEYEj14VmRuZBkqFbiwReogJgS1zR1n"
+	h, err := mh.FromB58String(theHash)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	assertions := [][]interface{}{
+		[]interface{}{NewCidV0(h), theHash},
+		[]interface{}{NewCidV0(h).Bytes(), theHash},
+		[]interface{}{h, theHash},
+		[]interface{}{theHash, theHash},
+		[]interface{}{"/ipfs/" + theHash, theHash},
+		[]interface{}{"https://ipfs.io/ipfs/" + theHash, theHash},
+		[]interface{}{"http://localhost:8080/ipfs/" + theHash, theHash},
+	}
+
+	assert := func(arg interface{}, expected string) error {
+		cid, err = Parse(arg)
+		if err != nil {
+			return err
+		}
+		if cid.version != 0 {
+			return fmt.Errorf("expected version 0, got %s", string(cid.version))
+		}
+		actual := cid.Hash().B58String()
+		if actual != expected {
+			return fmt.Errorf("expected hash %s, got %s", expected, actual)
+		}
+		actual = cid.String()
+		if actual != expected {
+			return fmt.Errorf("expected string %s, got %s", expected, actual)
+		}
+		return nil
+	}
+
+	for _, args := range assertions {
+		err := assert(args[0], args[1].(string))
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+}
+
+func TestHexDecode(t *testing.T) {
+	hexcid := "f015512209d8453505bdc6f269678e16b3e56c2a2948a41f2c792617cc9611ed363c95b63"
+	c, err := Decode(hexcid)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if c.String() != "zb2rhhFAEMepUBbGyP1k8tGfz7BSciKXP6GHuUeUsJBaK6cqG" {
+		t.Fatal("hash value failed to round trip decoding from hex")
+	}
+}
+
+func ExampleDecode() {
+	encoded := "zb2rhhFAEMepUBbGyP1k8tGfz7BSciKXP6GHuUeUsJBaK6cqG"
+	c, err := Decode(encoded)
+	if err != nil {
+		fmt.Printf("Error: %s", err)
+		return
+	}
+
+	fmt.Println(c)
+	// Output: zb2rhhFAEMepUBbGyP1k8tGfz7BSciKXP6GHuUeUsJBaK6cqG
+}
+
+func TestFromJson(t *testing.T) {
+	cval := "zb2rhhFAEMepUBbGyP1k8tGfz7BSciKXP6GHuUeUsJBaK6cqG"
+	jsoncid := []byte(`{"/":"` + cval + `"}`)
+	var c Cid
+	err := json.Unmarshal(jsoncid, &c)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if c.String() != cval {
+		t.Fatal("json parsing failed")
+	}
+}

fuzz-data/corpus/cid0

@@ -0,0 +1 @@
+ ëgáD1üüÊe<C38A>-D˜/¹q3ø~å(Ä7`8–<38>‡n

fuzz-data/corpus/cid1

@@ -0,0 +1 @@
+
q -[<5B>ï<EFBFBD>h<EFBFBD>[<5B><10><>

package.json

@@ -9,22 +9,22 @@
   "gxDependencies": [
     {
       "author": "whyrusleeping",
-      "hash": "QmYDds3421prZgqKbLpEK7T9Aa2eVdQ7o3YarX1LVLdP2J",
+      "hash": "QmVGtdTZdTFaLsaj2RwdVG8jcjNNcp1DE914DKZ2kHmXHw",
       "name": "go-multihash",
-      "version": "1.0.0"
+      "version": "1.0.4"
     },
     {
       "author": "whyrusleeping",
-      "hash": "QmYiTi9mKBMjfiup7na7PhJK7QEZPdMTJenLdgFYVQ2NUv",
+      "hash": "Qme4T6BE4sQxg7ZouamF5M7Tx1ZFTqzcns7BkyQPXpoT99",
       "name": "go-multibase",
-      "version": "0.2.0"
+      "version": "0.2.4"
     }
   ],
   "gxVersion": "0.8.0",
   "language": "go",
-  "license": "",
+  "license": "MIT",
   "name": "go-cid",
   "releaseCmd": "git commit -a -m \"gx publish $VERSION\"",
-  "version": "0.5.1"
+  "version": "0.7.13"
 }
 

set.go

@@ -1,39 +1,49 @@
 package cid
 
+// Set is a implementation of a set of Cids, that is, a structure
+// to which holds a single copy of every Cids that is added to it.
 type Set struct {
 	set map[string]struct{}
 }
 
+// NewSet initializes and returns a new Set.
 func NewSet() *Set {
 	return &Set{set: make(map[string]struct{})}
 }
 
+// Add puts a Cid in the Set.
 func (s *Set) Add(c *Cid) {
 	s.set[string(c.Bytes())] = struct{}{}
 }
 
+// Has returns if the Set contains a given Cid.
 func (s *Set) Has(c *Cid) bool {
 	_, ok := s.set[string(c.Bytes())]
 	return ok
 }
 
+// Remove deletes a Cid from the Set.
 func (s *Set) Remove(c *Cid) {
 	delete(s.set, string(c.Bytes()))
 }
 
+// Len returns how many elements the Set has.
 func (s *Set) Len() int {
 	return len(s.set)
 }
 
+// Keys returns the Cids in the set.
 func (s *Set) Keys() []*Cid {
-	var out []*Cid
-	for k, _ := range s.set {
+	out := make([]*Cid, 0, len(s.set))
+	for k := range s.set {
 		c, _ := Cast([]byte(k))
 		out = append(out, c)
 	}
 	return out
 }
 
+// Visit adds a Cid to the set only if it is
+// not in it already.
 func (s *Set) Visit(c *Cid) bool {
 	if !s.Has(c) {
 		s.Add(c)
@@ -42,3 +52,16 @@ func (s *Set) Visit(c *Cid) bool {
 
 	return false
 }
+
+// ForEach allows to run a custom function on each
+// Cid in the set.
+func (s *Set) ForEach(f func(c *Cid) error) error {
+	for cs := range s.set {
+		c, _ := Cast([]byte(cs))
+		err := f(c)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}