gx publish 0.7.21

Add CID Prefix constructors.

.gx/lastpubver

@@ -1 +1 @@
-0.7.10: QmTau856czj6wc5UyKQX2MfBQZ9iCZPsuUsVW2b2pRtLVp
+0.7.21: QmapdYm1b22Frv3k17fqrBYTFRxwiaVJkB299Mfn33edeB

.travis.yml

@@ -1,24 +1,24 @@
-os:
-  - linux
-  - osx
+sudo: false
+
 
 language: go
-
 go:
-    - 1.7
-
-install: true
-
-before_install:
-  - make deps
-
+  - 'tip'
+  
+install:
+  - go get github.com/whyrusleeping/gx
+  - go get github.com/whyrusleeping/gx-go
+  - gx install --global
 script:
-  - go vet
-  - $GOPATH/bin/goveralls -service="travis-ci"
+  - gx test -v -race -coverprofile=coverage.txt -covermode=atomic .
+  
+after_success:
+  - bash <(curl -s https://codecov.io/bash)
 
 cache:
-    directories:
-        - $GOPATH/src/gx
+  directories:
+    - $GOPATH/src/gx
 
 notifications:
-  email: false
+email: false
+  

README.md

@@ -4,13 +4,15 @@ 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.
+> 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.
+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
@@ -23,20 +25,46 @@ It is used in go-ipfs and related packages to refer to a typed hunk of data.
 
 ## 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
 ```
 
-## Examples
+This will make sure that dependencies are rewritten to known working versions.
 
-To use CIDs, import it in your code like:
-```go
-import "github.com/ipfs/go-cid"
-```
+### Examples
 
-Then, depending on how you want to use it, something like one of the following examples should work:
+#### Parsing string input from users
 
-### Parsing string input from users
 ```go
 // Create a cid from a marshaled string
 c, err := cid.Decode("zdvgqEMYmNeH5fKciougvQcfzMcNjF3Z1tPouJ8C7pc3pe63k")
@@ -45,7 +73,8 @@ if err != nil {...}
 fmt.Println("Got CID: ", c)
 ```
 
-### Creating a CID from scratch
+#### Creating a CID from scratch
+
 ```go
 // Create a cid manually by specifying the 'prefix' parameters
 pref := cid.Prefix{
@@ -62,7 +91,8 @@ if err != nil {...}
 fmt.Println("Created CID: ", c)
 ```
 
-### Check if two CIDs match
+#### 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) {
@@ -70,7 +100,8 @@ if c1.Equals(c2) {
 }
 ```
 
-### Check if some data matches a given CID
+#### 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:

cid-fmt/main.go

@@ -0,0 +1,277 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"strings"
+
+	c "github.com/ipfs/go-cid"
+
+	mb "github.com/multiformats/go-multibase"
+	mh "github.com/multiformats/go-multihash"
+)
+
+func usage() {
+	fmt.Fprintf(os.Stderr, "usage: %s [-b multibase-code] [-v cid-version] <fmt-str> <cid> ...\n\n", os.Args[0])
+	fmt.Fprintf(os.Stderr, "<fmt-str> is either 'prefix' or a printf style format string:\n%s", fmtRef)
+	os.Exit(2)
+}
+
+const fmtRef = `
+   %% literal %
+   %b multibase name 
+   %B multibase code
+   %v version string
+   %V version number
+   %c codec name
+   %C codec code
+   %h multihash name
+   %H multihash code
+   %L hash digest length
+   %m multihash encoded in base %b (with multibase prefix)
+   %M multihash encoded in base %b without multibase prefix
+   %d hash digest encoded in base %b (with multibase prefix)
+   %D hash digest encoded in base %b without multibase prefix
+   %s cid string encoded in base %b (1)
+   %s cid string encoded in base %b without multibase prefix
+   %P cid prefix: %v-%c-%h-%L
+
+(1) For CID version 0 the multibase must be base58btc and no prefix is
+used.  For Cid version 1 the multibase prefix is included.
+`
+
+func main() {
+	if len(os.Args) < 2 {
+		usage()
+	}
+	newBase := mb.Encoding(-1)
+	var verConv func(cid *c.Cid) (*c.Cid, error)
+	args := os.Args[1:]
+outer:
+	for {
+		switch args[0] {
+		case "-b":
+			if len(args) < 2 {
+				usage()
+			}
+			if len(args[1]) != 1 {
+				fmt.Fprintf(os.Stderr, "Error: Invalid multibase code: %s\n", args[1])
+				os.Exit(2)
+			}
+			newBase = mb.Encoding(args[1][0])
+			args = args[2:]
+		case "-v":
+			if len(args) < 2 {
+				usage()
+			}
+			switch args[1] {
+			case "0":
+				verConv = toCidV0
+			case "1":
+				verConv = toCidV1
+			default:
+				fmt.Fprintf(os.Stderr, "Error: Invalid cid version: %s\n", args[1])
+				os.Exit(2)
+			}
+			args = args[2:]
+		default:
+			break outer
+		}
+	}
+	if len(args) < 2 {
+		usage()
+	}
+	fmtStr := args[0]
+	switch fmtStr {
+	case "prefix":
+		fmtStr = "%P"
+	default:
+		if strings.IndexByte(fmtStr, '%') == -1 {
+			fmt.Fprintf(os.Stderr, "Error: Invalid format string: %s\n", fmtStr)
+			os.Exit(2)
+		}
+	}
+	for _, cidStr := range args[1:] {
+		base, cid, err := decode(cidStr)
+		if err != nil {
+			fmt.Fprintf(os.Stdout, "!INVALID_CID!\n")
+			errorMsg("%s: %v", cidStr, err)
+			// Don't abort on a bad cid
+			continue
+		}
+		if newBase != -1 {
+			base = newBase
+		}
+		if verConv != nil {
+			cid, err = verConv(cid)
+			if err != nil {
+				fmt.Fprintf(os.Stdout, "!ERROR!\n")
+				errorMsg("%s: %v", cidStr, err)
+				// Don't abort on a bad conversion
+				continue
+			}
+		}
+		str, err := fmtCid(fmtStr, base, cid)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+			// An error here means a bad format string, no point in continuing
+			os.Exit(2)
+		}
+		fmt.Fprintf(os.Stdout, "%s\n", str)
+	}
+	os.Exit(exitCode)
+}
+
+var exitCode = 0
+
+func errorMsg(fmtStr string, a ...interface{}) {
+	fmt.Fprintf(os.Stderr, "Error: ")
+	fmt.Fprintf(os.Stderr, fmtStr, a...)
+	fmt.Fprintf(os.Stderr, "\n")
+	exitCode = 1
+}
+
+func decode(v string) (mb.Encoding, *c.Cid, error) {
+	if len(v) < 2 {
+		return 0, nil, c.ErrCidTooShort
+	}
+
+	if len(v) == 46 && v[:2] == "Qm" {
+		hash, err := mh.FromB58String(v)
+		if err != nil {
+			return 0, nil, err
+		}
+
+		return mb.Base58BTC, c.NewCidV0(hash), nil
+	}
+
+	base, data, err := mb.Decode(v)
+	if err != nil {
+		return 0, nil, err
+	}
+
+	cid, err := c.Cast(data)
+
+	return base, cid, err
+}
+
+const ERR_STR = "!ERROR!"
+
+func fmtCid(fmtStr string, base mb.Encoding, cid *c.Cid) (string, error) {
+	p := cid.Prefix()
+	out := new(bytes.Buffer)
+	var err error
+	for i := 0; i < len(fmtStr); i++ {
+		if fmtStr[i] != '%' {
+			out.WriteByte(fmtStr[i])
+			continue
+		}
+		i++
+		if i >= len(fmtStr) {
+			return "", fmt.Errorf("premature end of format string")
+		}
+		switch fmtStr[i] {
+		case '%':
+			out.WriteByte('%')
+		case 'b': // base name
+			out.WriteString(baseToString(base))
+		case 'B': // base code
+			out.WriteByte(byte(base))
+		case 'v': // version string
+			fmt.Fprintf(out, "cidv%d", p.Version)
+		case 'V': // version num
+			fmt.Fprintf(out, "%d", p.Version)
+		case 'c': // codec name
+			out.WriteString(codecToString(p.Codec))
+		case 'C': // codec code
+			fmt.Fprintf(out, "%d", p.Codec)
+		case 'h': // hash fun name
+			out.WriteString(hashToString(p.MhType))
+		case 'H': // hash fun code
+			fmt.Fprintf(out, "%d", p.MhType)
+		case 'L': // hash length
+			fmt.Fprintf(out, "%d", p.MhLength)
+		case 'm', 'M': // multihash encoded in base %b
+			out.WriteString(encode(base, cid.Hash(), fmtStr[i] == 'M'))
+		case 'd', 'D': // hash digest encoded in base %b
+			dec, err := mh.Decode(cid.Hash())
+			if err != nil {
+				out.WriteString(ERR_STR)
+				errorMsg("%v", err)
+				continue
+			}
+			out.WriteString(encode(base, dec.Digest, fmtStr[i] == 'D'))
+		case 's': // cid string encoded in base %b
+			str, err := cid.StringOfBase(base)
+			if err != nil {
+				out.WriteString(ERR_STR)
+				errorMsg("%v", err)
+				continue
+			}
+			out.WriteString(str)
+		case 'S': // cid string without base prefix
+			out.WriteString(encode(base, cid.Bytes(), true))
+		case 'P': // prefix
+			fmt.Fprintf(out, "cidv%d-%s-%s-%d",
+				p.Version,
+				codecToString(p.Codec),
+				hashToString(p.MhType),
+				p.MhLength,
+			)
+		default:
+			return "", fmt.Errorf("unrecognized specifier in format string: %c", fmtStr[i])
+		}
+
+	}
+	return out.String(), err
+}
+
+func baseToString(base mb.Encoding) string {
+	// FIXME: Use lookup tables when they are added to go-multibase
+	switch base {
+	case mb.Base58BTC:
+		return "base58btc"
+	default:
+		return fmt.Sprintf("base?%c", base)
+	}
+}
+
+func codecToString(num uint64) string {
+	name, ok := c.CodecToStr[num]
+	if !ok {
+		return fmt.Sprintf("codec?%d", num)
+	}
+	return name
+}
+
+func hashToString(num uint64) string {
+	name, ok := mh.Codes[num]
+	if !ok {
+		return fmt.Sprintf("hash?%d", num)
+	}
+	return name
+}
+
+func encode(base mb.Encoding, data []byte, strip bool) string {
+	str, err := mb.Encode(base, data)
+	if err != nil {
+		errorMsg("%v", err)
+		return ERR_STR
+	}
+	if strip {
+		return str[1:]
+	}
+	return str
+}
+
+func toCidV0(cid *c.Cid) (*c.Cid, error) {
+	if cid.Type() != c.DagProtobuf {
+		return nil, fmt.Errorf("can't convert non-protobuf nodes to cidv0")
+	}
+	return c.NewCidV0(cid.Hash()), nil
+}
+
+func toCidV1(cid *c.Cid) (*c.Cid, error) {
+	return c.NewCidV1(cid.Type(), cid.Hash()), nil
+}

cid-fmt/main_test.go

@@ -0,0 +1,109 @@
+package main
+
+import (
+	"fmt"
+	"testing"
+
+	mb "github.com/multiformats/go-multibase"
+)
+
+func TestFmt(t *testing.T) {
+	cids := map[string]string{
+		"cidv0": "QmUNLLsPACCz1vLxQVkXqqLX5R1X345qqfHbsf67hvA3Nn",
+		"cidv1": "zdj7WfLr9DhLrb1hsoSi4fSdjjxuZmeqgEtBPWxMLtPbDNbFD",
+	}
+	tests := []struct {
+		cidId   string
+		newBase mb.Encoding
+		fmtStr  string
+		result  string
+	}{
+		{"cidv0", -1, "%P", "cidv0-protobuf-sha2-256-32"},
+		{"cidv0", -1, "%b-%v-%c-%h-%L", "base58btc-cidv0-protobuf-sha2-256-32"},
+		{"cidv0", -1, "%s", "QmUNLLsPACCz1vLxQVkXqqLX5R1X345qqfHbsf67hvA3Nn"},
+		{"cidv0", -1, "%S", "QmUNLLsPACCz1vLxQVkXqqLX5R1X345qqfHbsf67hvA3Nn"},
+		{"cidv0", -1, "ver#%V/#%C/#%H/%L", "ver#0/#112/#18/32"},
+		{"cidv0", -1, "%m", "zQmUNLLsPACCz1vLxQVkXqqLX5R1X345qqfHbsf67hvA3Nn"},
+		{"cidv0", -1, "%M", "QmUNLLsPACCz1vLxQVkXqqLX5R1X345qqfHbsf67hvA3Nn"},
+		{"cidv0", -1, "%d", "z72gdmFAgRzYHkJzKiL8MgMMRW3BTSCGyDHroPxJbxMJn"},
+		{"cidv0", -1, "%D", "72gdmFAgRzYHkJzKiL8MgMMRW3BTSCGyDHroPxJbxMJn"},
+		{"cidv0", 'B', "%S", "CIQFTFEEHEDF6KLBT32BFAGLXEZL4UWFNWM4LFTLMXQBCERZ6CMLX3Y"},
+		{"cidv0", 'B', "%B%S", "BCIQFTFEEHEDF6KLBT32BFAGLXEZL4UWFNWM4LFTLMXQBCERZ6CMLX3Y"},
+		{"cidv1", -1, "%P", "cidv1-protobuf-sha2-256-32"},
+		{"cidv1", -1, "%b-%v-%c-%h-%L", "base58btc-cidv1-protobuf-sha2-256-32"},
+		{"cidv1", -1, "%s", "zdj7WfLr9DhLrb1hsoSi4fSdjjxuZmeqgEtBPWxMLtPbDNbFD"},
+		{"cidv1", -1, "%S", "dj7WfLr9DhLrb1hsoSi4fSdjjxuZmeqgEtBPWxMLtPbDNbFD"},
+		{"cidv1", -1, "ver#%V/#%C/#%H/%L", "ver#1/#112/#18/32"},
+		{"cidv1", -1, "%m", "zQmYFbmndVP7QqAVWyKhpmMuQHMaD88pkK57RgYVimmoh5H"},
+		{"cidv1", -1, "%M", "QmYFbmndVP7QqAVWyKhpmMuQHMaD88pkK57RgYVimmoh5H"},
+		{"cidv1", -1, "%d", "zAux4gVVsLRMXtsZ9fd3tFEZN4jGYB6kP37fgoZNTc11H"},
+		{"cidv1", -1, "%D", "Aux4gVVsLRMXtsZ9fd3tFEZN4jGYB6kP37fgoZNTc11H"},
+		{"cidv1", 'B', "%s", "BAFYBEIETJGSRL3EQPQPCABV3G6IUBYTSIFVQ24XRRHD3JUETSKLTGQ7DJA"},
+		{"cidv1", 'B', "%S", "AFYBEIETJGSRL3EQPQPCABV3G6IUBYTSIFVQ24XRRHD3JUETSKLTGQ7DJA"},
+		{"cidv1", 'B', "%B%S", "BAFYBEIETJGSRL3EQPQPCABV3G6IUBYTSIFVQ24XRRHD3JUETSKLTGQ7DJA"},
+	}
+	for _, tc := range tests {
+		name := fmt.Sprintf("%s/%s", tc.cidId, tc.fmtStr)
+		if tc.newBase != -1 {
+			name = fmt.Sprintf("%s/%c", name, tc.newBase)
+		}
+		cidStr := cids[tc.cidId]
+		t.Run(name, func(t *testing.T) {
+			testFmt(t, cidStr, tc.newBase, tc.fmtStr, tc.result)
+		})
+	}
+}
+
+func testFmt(t *testing.T, cidStr string, newBase mb.Encoding, fmtStr string, result string) {
+	base, cid, err := decode(cidStr)
+	if newBase != -1 {
+		base = newBase
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+	str, err := fmtCid(fmtStr, base, cid)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if str != result {
+		t.Error(fmt.Sprintf("expected: %s; but got: %s", result, str))
+	}
+}
+
+func TestCidConv(t *testing.T) {
+	cidv0 := "QmUNLLsPACCz1vLxQVkXqqLX5R1X345qqfHbsf67hvA3Nn"
+	cidv1 := "zdj7WbTaiJT1fgatdet9Ei9iDB5hdCxkbVyhyh8YTUnXMiwYi"
+	_, cid, err := decode(cidv0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cid, err = toCidV1(cid)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if cid.String() != cidv1 {
+		t.Fatal("conversion failure")
+	}
+	cid, err = toCidV0(cid)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cidStr := cid.String()
+	if cidStr != cidv0 {
+		t.Error(fmt.Sprintf("conversion failure, expected: %s; but got: %s", cidv0, cidStr))
+	}
+}
+
+func TestBadCidConv(t *testing.T) {
+	// this cid is a raw leaf and should not be able to convert to cidv0
+	cidv1 := "zb2rhhzX7uSKrtQ2ZZXFAabKiKFYZrJqKY2KE1cJ8yre2GSWZ"
+	_, cid, err := decode(cidv1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cid, err = toCidV0(cid)
+	if err == nil {
+		t.Fatal("expected failure")
+	}
+}

cid.go

@@ -1,8 +1,28 @@
+// 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"
@@ -11,44 +31,151 @@ import (
 	mh "github.com/multiformats/go-multihash"
 )
 
+// UnsupportedVersionString just holds an error message
 const UnsupportedVersionString = "<unsupported cid version>"
 
+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")
+
+	// ErrInvalidEncoding means that selected encoding is not supported
+	// by this Cid version
+	ErrInvalidEncoding = errors.New("invalid base encoding")
+)
+
+// 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
 
-	EthereumBlock = 0x90
-	EthereumTx    = 0x91
-	BitcoinBlock  = 0xb0
-	BitcoinTx     = 0xb1
-	ZcashBlock    = 0xc0
-	ZcashTx       = 0xc1
+	GitRaw = 0x78
+
+	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
 )
 
-func NewCidV0(h mh.Multihash) *Cid {
+// Codecs maps the name of a codec to its type
+var Codecs = map[string]uint64{
+	"v0":                   DagProtobuf,
+	"raw":                  Raw,
+	"protobuf":             DagProtobuf,
+	"cbor":                 DagCBOR,
+	"git-raw":              GitRaw,
+	"eth-block":            EthBlock,
+	"eth-block-list":       EthBlockList,
+	"eth-tx-trie":          EthTxTrie,
+	"eth-tx":               EthTx,
+	"eth-tx-receipt-trie":  EthTxReceiptTrie,
+	"eth-tx-receipt":       EthTxReceipt,
+	"eth-state-trie":       EthStateTrie,
+	"eth-account-snapshot": EthAccountSnapshot,
+	"eth-storage-trie":     EthStorageTrie,
+	"bitcoin-block":        BitcoinBlock,
+	"bitcoin-tx":           BitcoinTx,
+	"zcash-block":          ZcashBlock,
+	"zcash-tx":             ZcashTx,
+}
+
+// CodecToStr maps the numeric codec to its name
+var CodecToStr = map[uint64]string{
+	Raw:                "raw",
+	DagProtobuf:        "protobuf",
+	DagCBOR:            "cbor",
+	GitRaw:             "git-raw",
+	EthBlock:           "eth-block",
+	EthBlockList:       "eth-block-list",
+	EthTxTrie:          "eth-tx-trie",
+	EthTx:              "eth-tx",
+	EthTxReceiptTrie:   "eth-tx-receipt-trie",
+	EthTxReceipt:       "eth-tx-receipt",
+	EthStateTrie:       "eth-state-trie",
+	EthAccountSnapshot: "eth-account-snapshot",
+	EthStorageTrie:     "eth-storage-trie",
+	BitcoinBlock:       "bitcoin-block",
+	BitcoinTx:          "bitcoin-tx",
+	ZcashBlock:         "zcash-block",
+	ZcashTx:            "zcash-tx",
+}
+
+// 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:   DagProtobuf,
-		hash:    h,
+		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,
 	}
 }
 
+// NewPrefixV0 returns a CIDv0 prefix with the specified multihash type.
+func NewPrefixV0(mhType uint64) Prefix {
+	return Prefix{
+		MhType:   mhType,
+		MhLength: mh.DefaultLengths[mhType],
+		Version:  0,
+		Codec:    DagProtobuf,
+	}
+}
+
+// NewPrefixV1 returns a CIDv1 prefix with the specified codec and multihash
+// type.
+func NewPrefixV1(codecType uint64, mhType uint64) Prefix {
+	return Prefix{
+		MhType:   mhType,
+		MhLength: mh.DefaultLengths[mhType],
+		Version:  1,
+		Codec:    codecType,
+	}
+}
+
+// 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:
@@ -67,9 +194,21 @@ func Parse(v interface{}) (*Cid, error) {
 	}
 }
 
+// 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, fmt.Errorf("cid too short")
+		return nil, ErrCidTooShort
 	}
 
 	if len(v) == 46 && v[:2] == "Qm" {
@@ -89,12 +228,6 @@ func Decode(v string) (*Cid, error) {
 	return Cast(data)
 }
 
-var (
-	ErrVarintBuffSmall = errors.New("reading varint: buffer to small")
-	ErrVarintTooBig    = errors.New("reading varint: varint bigger than 64bits" +
-		" and not supported")
-)
-
 func uvError(read int) error {
 	switch {
 	case read == 0:
@@ -106,6 +239,17 @@ func uvError(read int) error {
 	}
 }
 
+// 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)
@@ -147,10 +291,14 @@ 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:
@@ -167,10 +315,30 @@ func (c *Cid) String() string {
 	}
 }
 
+// String returns the string representation of a Cid
+// encoded is selected base
+func (c *Cid) StringOfBase(base mbase.Encoding) (string, error) {
+	switch c.version {
+	case 0:
+		if base != mbase.Base58BTC {
+			return "", ErrInvalidEncoding
+		}
+		return c.hash.B58String(), nil
+	case 1:
+		return mbase.Encode(base, c.bytesV1())
+	default:
+		panic("not possible to reach this point")
+	}
+}
+
+// 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:
@@ -199,17 +367,33 @@ func (c *Cid) bytesV1() []byte {
 	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
 	}
@@ -220,20 +404,30 @@ 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{
@@ -244,7 +438,10 @@ func (c *Cid) Prefix() Prefix {
 	}
 }
 
-// Prefix represents all the metadata of a cid, minus any actual content information
+// 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
@@ -252,6 +449,8 @@ type Prefix struct {
 	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 {
@@ -268,6 +467,9 @@ func (p Prefix) Sum(data []byte) (*Cid, error) {
 	}
 }
 
+// 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)
@@ -277,6 +479,8 @@ func (p Prefix) Bytes() []byte {
 	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)

cid_test.go

@@ -2,14 +2,39 @@ package cid
 
 import (
 	"bytes"
+	"encoding/json"
 	"fmt"
 	"math/rand"
 	"strings"
 	"testing"
 
+	mbase "github.com/multiformats/go-multibase"
 	mh "github.com/multiformats/go-multihash"
 )
 
+// Copying the "silly test" idea from
+// https://github.com/multiformats/go-multihash/blob/7aa9f26a231c6f34f4e9fad52bf580fd36627285/multihash_test.go#L13
+// Makes it so changing the table accidentally has to happen twice.
+var tCodecs = map[uint64]string{
+	Raw:                "raw",
+	DagProtobuf:        "protobuf",
+	DagCBOR:            "cbor",
+	GitRaw:             "git-raw",
+	EthBlock:           "eth-block",
+	EthBlockList:       "eth-block-list",
+	EthTxTrie:          "eth-tx-trie",
+	EthTx:              "eth-tx",
+	EthTxReceiptTrie:   "eth-tx-receipt-trie",
+	EthTxReceipt:       "eth-tx-receipt",
+	EthStateTrie:       "eth-state-trie",
+	EthAccountSnapshot: "eth-account-snapshot",
+	EthStorageTrie:     "eth-storage-trie",
+	BitcoinBlock:       "bitcoin-block",
+	BitcoinTx:          "bitcoin-tx",
+	ZcashBlock:         "zcash-block",
+	ZcashTx:            "zcash-tx",
+}
+
 func assertEqual(t *testing.T, a, b *Cid) {
 	if a.codec != b.codec {
 		t.Fatal("mismatch on type")
@@ -24,6 +49,26 @@ func assertEqual(t *testing.T, a, b *Cid) {
 	}
 }
 
+func TestTable(t *testing.T) {
+	if len(tCodecs) != len(Codecs)-1 {
+		t.Errorf("Item count mismatch in the Table of Codec. Should be %d, got %d", len(tCodecs)+1, len(Codecs))
+	}
+
+	for k, v := range tCodecs {
+		if Codecs[v] != k {
+			t.Errorf("Table mismatch: 0x%x %s", k, v)
+		}
+	}
+}
+
+// The table returns cid.DagProtobuf for "v0"
+// so we test it apart
+func TestTableForV0(t *testing.T) {
+	if Codecs["v0"] != DagProtobuf {
+		t.Error("Table mismatch: Codecs[\"v0\"] should resolve to DagProtobuf (0x70)")
+	}
+}
+
 func TestBasicMarshaling(t *testing.T) {
 	h, err := mh.Sum([]byte("TEST"), mh.SHA3, 4)
 	if err != nil {
@@ -54,6 +99,60 @@ func TestBasicMarshaling(t *testing.T) {
 	assertEqual(t, cid, out2)
 }
 
+func TestBasesMarshaling(t *testing.T) {
+	h, err := mh.Sum([]byte("TEST"), mh.SHA3, 4)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	cid := &Cid{
+		codec:   7,
+		version: 1,
+		hash:    h,
+	}
+
+	data := cid.Bytes()
+
+	out, err := Cast(data)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	assertEqual(t, cid, out)
+
+	testBases := []mbase.Encoding{
+		mbase.Base16,
+		mbase.Base32,
+		mbase.Base32hex,
+		mbase.Base32pad,
+		mbase.Base32hexPad,
+		mbase.Base58BTC,
+		mbase.Base58Flickr,
+		mbase.Base64pad,
+		mbase.Base64urlPad,
+		mbase.Base64url,
+		mbase.Base64,
+	}
+
+	for _, b := range testBases {
+		s, err := cid.StringOfBase(b)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if s[0] != byte(b) {
+			t.Fatal("Invalid multibase header")
+		}
+
+		out2, err := Decode(s)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		assertEqual(t, cid, out2)
+	}
+}
+
 func TestEmptyString(t *testing.T) {
 	_, err := Decode("")
 	if err == nil {
@@ -90,6 +189,64 @@ func TestV0ErrorCases(t *testing.T) {
 	}
 }
 
+func TestNewPrefixV1(t *testing.T) {
+	data := []byte("this is some test content")
+
+	// Construct c1
+	prefix := NewPrefixV1(DagCBOR, mh.SHA2_256)
+	c1, err := prefix.Sum(data)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if c1.Prefix() != prefix {
+		t.Fatal("prefix not preserved")
+	}
+
+	// Construct c2
+	hash, err := mh.Sum(data, mh.SHA2_256, -1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	c2 := NewCidV1(DagCBOR, hash)
+
+	if !c1.Equals(c2) {
+		t.Fatal("cids mismatch")
+	}
+	if c1.Prefix() != c2.Prefix() {
+		t.Fatal("prefixes mismatch")
+	}
+}
+
+func TestNewPrefixV0(t *testing.T) {
+	data := []byte("this is some test content")
+
+	// Construct c1
+	prefix := NewPrefixV0(mh.SHA2_256)
+	c1, err := prefix.Sum(data)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if c1.Prefix() != prefix {
+		t.Fatal("prefix not preserved")
+	}
+
+	// Construct c2
+	hash, err := mh.Sum(data, mh.SHA2_256, -1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	c2 := NewCidV0(hash)
+
+	if !c1.Equals(c2) {
+		t.Fatal("cids mismatch")
+	}
+	if c1.Prefix() != c2.Prefix() {
+		t.Fatal("prefixes mismatch")
+	}
+}
+
 func TestPrefixRoundtrip(t *testing.T) {
 	data := []byte("this is some test content")
 	hash, _ := mh.Sum(data, mh.SHA2_256, -1)
@@ -200,3 +357,29 @@ func TestHexDecode(t *testing.T) {
 		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")
+	}
+}

codecov.yml

@@ -0,0 +1,3 @@
+coverage:
+  range: "50...100"
+comment: off

package.json

@@ -9,15 +9,15 @@
   "gxDependencies": [
     {
       "author": "whyrusleeping",
-      "hash": "QmbZ6Cee2uHjG7hf19qLHppgKDRtaG4CVtMzdmK9VCVqLu",
+      "hash": "QmPnFwZ2JXKnXgMw8CdBPxn7FWh6LLdjUjxV1fKHuJnkr8",
       "name": "go-multihash",
-      "version": "1.0.2"
+      "version": "1.0.8"
     },
     {
       "author": "whyrusleeping",
-      "hash": "QmcxkxTVuURV2Ptse8TvkqH5BQDwV62X1x19JqqvbBzwUM",
+      "hash": "QmexBtiTTEwwn42Yi6ouKt6VqzpA6wjJgiW1oh9VfaRrup",
       "name": "go-multibase",
-      "version": "0.2.3"
+      "version": "0.2.6"
     }
   ],
   "gxVersion": "0.8.0",
@@ -25,6 +25,6 @@
   "license": "MIT",
   "name": "go-cid",
   "releaseCmd": "git commit -a -m \"gx publish $VERSION\"",
-  "version": "0.7.10"
+  "version": "0.7.21"
 }
 

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 {
 	out := make([]*Cid, 0, len(s.set))
-	for k, _ := range 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)
@@ -43,8 +53,10 @@ 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 {
+	for cs := range s.set {
 		c, _ := Cast([]byte(cs))
 		err := f(c)
 		if err != nil {