Add SumStream to read data from io.Reader

This provides a way to create a CID without having to read all data into memory before passing it into Sum.  Instead, call SumStream passing in an io.Reader.

README.md

@@ -88,7 +88,7 @@ if c1.Equals(c2) {
 ```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)
+other, err := c.Prefix().SumStream(myFile)
 if err != nil {...}
 
 if !c.Equals(other) {

builder.go

@@ -1,6 +1,8 @@
 package cid
 
 import (
+	"io"
+
 	mh "github.com/multiformats/go-multihash"
 )
 
@@ -41,6 +43,14 @@ func (p V0Builder) Sum(data []byte) (Cid, error) {
 	return Cid{string(hash)}, nil
 }
 
+func (p V0Builder) SumStream(r io.Reader) (Cid, error) {
+	hash, err := mh.SumStream(r, mh.SHA2_256, -1)
+	if err != nil {
+		return Undef, err
+	}
+	return Cid{string(hash)}, nil
+}
+
 func (p V0Builder) GetCodec() uint64 {
 	return DagProtobuf
 }
@@ -64,6 +74,18 @@ func (p V1Builder) Sum(data []byte) (Cid, error) {
 	return NewCidV1(p.Codec, hash), nil
 }
 
+func (p V1Builder) SumStream(r io.Reader) (Cid, error) {
+	mhLen := p.MhLength
+	if mhLen <= 0 {
+		mhLen = -1
+	}
+	hash, err := mh.SumStream(r, p.MhType, mhLen)
+	if err != nil {
+		return Undef, err
+	}
+	return NewCidV1(p.Codec, hash), nil
+}
+
 func (p V1Builder) GetCodec() uint64 {
 	return p.Codec
 }

builder_test.go

@@ -1,6 +1,7 @@
 package cid
 
 import (
+	"bytes"
 	"testing"
 
 	mh "github.com/multiformats/go-multihash"
@@ -16,6 +17,15 @@ func TestV0Builder(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	reader := bytes.NewReader(data)
+	c1a, err := format.SumStream(reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !c1a.Equals(c1) {
+		t.Fatal("Sum and SumStream create different cids")
+	}
+
 	// Construct c2
 	hash, err := mh.Sum(data, mh.SHA2_256, -1)
 	if err != nil {
@@ -29,6 +39,16 @@ func TestV0Builder(t *testing.T) {
 	if c1.Prefix() != c2.Prefix() {
 		t.Fatal("prefixes mismatch")
 	}
+
+	reader.Seek(0, 0)
+	hash, err = mh.SumStream(reader, mh.SHA2_256, -1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	c2 = NewCidV0(hash)
+	if !c1.Equals(c2) {
+		t.Fatal("Sum and SumStream create different cids")
+	}
 }
 
 func TestV1Builder(t *testing.T) {
@@ -41,6 +61,15 @@ func TestV1Builder(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	reader := bytes.NewReader(data)
+	c1a, err := format.SumStream(reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !c1a.Equals(c1) {
+		t.Fatal("Sum and SumStream create different cids")
+	}
+
 	// Construct c2
 	hash, err := mh.Sum(data, mh.SHA2_256, -1)
 	if err != nil {
@@ -65,9 +94,29 @@ func TestCodecChange(t *testing.T) {
 		p := Prefix{Version: 1, Codec: DagProtobuf, MhType: mh.SHA2_256, MhLength: mh.DefaultLengths[mh.SHA2_256]}
 		testCodecChange(t, p)
 	})
+	t.Run("Prefix-NoChange", func(t *testing.T) {
+		p := Prefix{Version: 0, Codec: DagProtobuf, MhType: mh.SHA2_256, MhLength: mh.DefaultLengths[mh.SHA2_256]}
+		if p.GetCodec() != DagProtobuf {
+			t.Fatal("original builder not using Protobuf codec")
+		}
+		pn := p.WithCodec(DagProtobuf)
+		if pn != p {
+			t.Fatal("should have returned same builder")
+		}
+	})
 	t.Run("V0Builder", func(t *testing.T) {
 		testCodecChange(t, V0Builder{})
 	})
+	t.Run("V0Builder-NoChange", func(t *testing.T) {
+		b := V0Builder{}
+		if b.GetCodec() != DagProtobuf {
+			t.Fatal("original builder not using Protobuf codec")
+		}
+		bn := b.WithCodec(DagProtobuf)
+		if bn != b {
+			t.Fatal("should have returned same builder")
+		}
+	})
 	t.Run("V1Builder", func(t *testing.T) {
 		testCodecChange(t, V1Builder{Codec: DagProtobuf, MhType: mh.SHA2_256})
 	})

cid.go

@@ -58,6 +58,7 @@ const (
 
 	GitRaw = 0x78
 
+	DagJOSE               = 0x85
 	EthBlock              = 0x90
 	EthBlockList          = 0x91
 	EthTxTrie             = 0x92
@@ -106,6 +107,7 @@ var Codecs = map[string]uint64{
 	"dash-tx":                 DashTx,
 	"fil-commitment-unsealed": FilCommitmentUnsealed,
 	"fil-commitment-sealed":   FilCommitmentSealed,
+	"dag-jose":                DagJOSE,
 }
 
 // CodecToStr maps the numeric codec to its name
@@ -133,6 +135,7 @@ var CodecToStr = map[uint64]string{
 	DashTx:                "dash-tx",
 	FilCommitmentUnsealed: "fil-commitment-unsealed",
 	FilCommitmentSealed:   "fil-commitment-sealed",
+	DagJOSE:               "dag-jose",
 }
 
 // tryNewCidV0 tries to convert a multihash into a CIDv0 CID and returns an
@@ -518,12 +521,29 @@ func (c Cid) Loggable() map[string]interface{} {
 
 // 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
+	if c.Version() == 0 {
+		return Prefix{
+			MhType:   mh.SHA2_256,
+			MhLength: 32,
+			Version:  0,
+			Codec:    DagProtobuf,
+		}
+	}
+
+	offset := 0
+	version, n, _ := uvarint(c.str[offset:])
+	offset += n
+	codec, n, _ := uvarint(c.str[offset:])
+	offset += n
+	mhtype, n, _ := uvarint(c.str[offset:])
+	offset += n
+	mhlen, _, _ := uvarint(c.str[offset:])
+
 	return Prefix{
-		MhType:   dec.Code,
-		MhLength: dec.Length,
-		Version:  c.Version(),
-		Codec:    c.Type(),
+		MhType:   mhtype,
+		MhLength: int(mhlen),
+		Version:  version,
+		Codec:    codec,
 	}
 }
 
@@ -569,6 +589,36 @@ func (p Prefix) Sum(data []byte) (Cid, error) {
 	}
 }
 
+// SumStream uses the information in a prefix, and data read from a io.Reader,
+// to perform a multihash.SumStream() and return a newly constructed Cid with
+// the resulting multihash.
+func (p Prefix) SumStream(r io.Reader) (Cid, error) {
+	length := p.MhLength
+	if p.MhType == mh.ID {
+		length = -1
+	}
+
+	if p.Version == 0 && (p.MhType != mh.SHA2_256 ||
+		(p.MhLength != 32 && p.MhLength != -1)) {
+
+		return Undef, fmt.Errorf("invalid v0 prefix")
+	}
+
+	hash, err := mh.SumStream(r, p.MhType, length)
+	if err != nil {
+		return Undef, err
+	}
+
+	switch p.Version {
+	case 0:
+		return NewCidV0(hash), nil
+	case 1:
+		return NewCidV1(p.Codec, hash), nil
+	default:
+		return Undef, fmt.Errorf("invalid cid version")
+	}
+}
+
 // Bytes returns a byte representation of a Prefix. It looks like:
 //
 //     <version><codec><mh-type><mh-length>

cid_test.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"math/rand"
+	"reflect"
 	"strings"
 	"testing"
 
@@ -40,6 +41,7 @@ var tCodecs = map[uint64]string{
 	DashTx:                "dash-tx",
 	FilCommitmentUnsealed: "fil-commitment-unsealed",
 	FilCommitmentSealed:   "fil-commitment-sealed",
+	DagJOSE:               "dag-jose",
 }
 
 func assertEqual(t *testing.T, a, b Cid) {
@@ -184,8 +186,32 @@ func TestBasesMarshaling(t *testing.T) {
 		}
 		s2 := cid.Encode(encoder)
 		if s != s2 {
-			t.Fatalf("'%s' != '%s'", s, s2)
+			t.Fatalf("%q != %q", s, s2)
 		}
+
+		ee, err := ExtractEncoding(s)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if ee != b {
+			t.Fatalf("could not properly determine base (got %v)", ee)
+		}
+	}
+
+	ee, err := ExtractEncoding("QmdfTbBqBPQ7VNxZEYEj14VmRuZBkqFbiwReogJgS1zR1n")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if ee != mbase.Base58BTC {
+		t.Fatalf("expected Base58BTC from Qm string (got %v)", ee)
+	}
+
+	ee, err = ExtractEncoding("1")
+	if err == nil {
+		t.Fatal("expected too-short error from ExtractEncoding")
+	}
+	if ee != -1 {
+		t.Fatal("expected -1 from too-short ExtractEncoding")
 	}
 }
 
@@ -194,18 +220,32 @@ func TestBinaryMarshaling(t *testing.T) {
 	hash, _ := mh.Sum(data, mh.SHA2_256, -1)
 	c := NewCidV1(DagCBOR, hash)
 	var c2 Cid
+	var c3 Cid
 
 	data, err := c.MarshalBinary()
 	if err != nil {
 		t.Fatal(err)
 	}
-	err = c2.UnmarshalBinary(data)
-	if err != nil {
+	if err = c2.UnmarshalBinary(data); err != nil {
 		t.Fatal(err)
 	}
 	if !c.Equals(c2) {
 		t.Errorf("cids should be the same: %s %s", c, c2)
 	}
+	var buf bytes.Buffer
+	wrote, err := c.WriteBytes(&buf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if wrote != 36 {
+		t.Fatalf("expected 36 bytes written (got %d)", wrote)
+	}
+	if err = c3.UnmarshalBinary(data); err != nil {
+		t.Fatal(err)
+	}
+	if !c.Equals(c3) {
+		t.Errorf("cids should be the same: %s %s", c, c3)
+	}
 }
 
 func TestTextMarshaling(t *testing.T) {
@@ -218,13 +258,16 @@ func TestTextMarshaling(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	err = c2.UnmarshalText(data)
-	if err != nil {
+	if err = c2.UnmarshalText(data); err != nil {
 		t.Fatal(err)
 	}
 	if !c.Equals(c2) {
 		t.Errorf("cids should be the same: %s %s", c, c2)
 	}
+
+	if c.KeyString() != string(c.Bytes()) {
+		t.Errorf("got unexpected KeyString() result")
+	}
 }
 
 func TestEmptyString(t *testing.T) {
@@ -254,6 +297,11 @@ func TestV0Handling(t *testing.T) {
 		t.Fatal("marshaling roundtrip failed")
 	}
 
+	byteLen := cid.ByteLen()
+	if byteLen != 34 {
+		t.Fatalf("expected V0 ByteLen to be 34 (got %d)", byteLen)
+	}
+
 	new, err := cid.StringOfBase(mbase.Base58BTC)
 	if err != nil {
 		t.Fatal(err)
@@ -269,6 +317,11 @@ func TestV0Handling(t *testing.T) {
 	if cid.Encode(encoder) != old {
 		t.Fatal("Encode roundtrip failed")
 	}
+
+	_, err = cid.StringOfBase(mbase.Base32)
+	if err != ErrInvalidEncoding {
+		t.Fatalf("expected ErrInvalidEncoding for V0 StringOfBase(Base32) (got %v)", err)
+	}
 }
 
 func TestV0ErrorCases(t *testing.T) {
@@ -369,7 +422,14 @@ func TestInvalidV0Prefix(t *testing.T) {
 			t.Fatalf("should error (index %d)", i)
 		}
 	}
+}
 
+func TestBadPrefix(t *testing.T) {
+	p := Prefix{Version: 3, Codec: DagProtobuf, MhType: mh.SHA2_256, MhLength: 3}
+	_, err := p.Sum([]byte{0x00, 0x01, 0x03})
+	if err == nil {
+		t.Fatalf("expected error on v3 prefix Sum")
+	}
 }
 
 func TestPrefixRoundtrip(t *testing.T) {
@@ -401,6 +461,25 @@ func TestPrefixRoundtrip(t *testing.T) {
 	}
 }
 
+func TestBadPrefixFromBytes(t *testing.T) {
+	_, err := PrefixFromBytes([]byte{0x80})
+	if err == nil {
+		t.Fatal("expected error for bad byte 0")
+	}
+	_, err = PrefixFromBytes([]byte{0x01, 0x80})
+	if err == nil {
+		t.Fatal("expected error for bad byte 1")
+	}
+	_, err = PrefixFromBytes([]byte{0x01, 0x01, 0x80})
+	if err == nil {
+		t.Fatal("expected error for bad byte 2")
+	}
+	_, err = PrefixFromBytes([]byte{0x01, 0x01, 0x01, 0x80})
+	if err == nil {
+		t.Fatal("expected error for bad byte 3")
+	}
+}
+
 func Test16BytesVarint(t *testing.T) {
 	data := []byte("this is some test content")
 	hash, _ := mh.Sum(data, mh.SHA2_256, -1)
@@ -448,7 +527,7 @@ func TestParse(t *testing.T) {
 			return err
 		}
 		if cid.Version() != 0 {
-			return fmt.Errorf("expected version 0, got %s", string(cid.Version()))
+			return fmt.Errorf("expected version 0, got %d", cid.Version())
 		}
 		actual := cid.Hash().B58String()
 		if actual != expected {
@@ -462,8 +541,7 @@ func TestParse(t *testing.T) {
 	}
 
 	for _, args := range assertions {
-		err := assert(args[0], args[1].(string))
-		if err != nil {
+		if err := assert(args[0], args[1].(string)); err != nil {
 			t.Fatal(err)
 		}
 	}
@@ -497,8 +575,7 @@ func TestFromJson(t *testing.T) {
 	cval := "bafkreie5qrjvaw64n4tjm6hbnm7fnqvcssfed4whsjqxzslbd3jwhsk3mm"
 	jsoncid := []byte(`{"/":"` + cval + `"}`)
 	var c Cid
-	err := json.Unmarshal(jsoncid, &c)
-	if err != nil {
+	if err := json.Unmarshal(jsoncid, &c); err != nil {
 		t.Fatal(err)
 	}
 
@@ -508,6 +585,7 @@ func TestFromJson(t *testing.T) {
 }
 
 func TestJsonRoundTrip(t *testing.T) {
+	expectedJSON := `{"/":"bafkreie5qrjvaw64n4tjm6hbnm7fnqvcssfed4whsjqxzslbd3jwhsk3mm"}`
 	exp, err := Decode("bafkreie5qrjvaw64n4tjm6hbnm7fnqvcssfed4whsjqxzslbd3jwhsk3mm")
 	if err != nil {
 		t.Fatal(err)
@@ -519,21 +597,50 @@ func TestJsonRoundTrip(t *testing.T) {
 		t.Fatal(err)
 	}
 	var actual Cid
-	err = json.Unmarshal(enc, &actual)
+	if err = json.Unmarshal(enc, &actual); err != nil {
+		t.Fatal(err)
+	}
 	if !exp.Equals(actual) {
 		t.Fatal("cids not equal for *Cid")
 	}
 
+	if string(enc) != expectedJSON {
+		t.Fatalf("did not get expected JSON form (got %q)", string(enc))
+	}
+
 	// Verify it works for a Cid.
 	enc, err = json.Marshal(exp)
 	if err != nil {
 		t.Fatal(err)
 	}
 	var actual2 Cid
-	err = json.Unmarshal(enc, &actual2)
+	if err = json.Unmarshal(enc, &actual2); err != nil {
+		t.Fatal(err)
+	}
 	if !exp.Equals(actual2) {
 		t.Fatal("cids not equal for Cid")
 	}
+
+	if err = actual2.UnmarshalJSON([]byte("1")); err == nil {
+		t.Fatal("expected error for too-short JSON")
+	}
+
+	if err = actual2.UnmarshalJSON([]byte(`{"nope":"nope"}`)); err == nil {
+		t.Fatal("expected error for bad CID JSON")
+	}
+
+	if err = actual2.UnmarshalJSON([]byte(`bad "" json!`)); err == nil {
+		t.Fatal("expected error for bad JSON")
+	}
+
+	var actual3 Cid
+	enc, err = actual3.MarshalJSON()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(enc) != "null" {
+		t.Fatalf("expected 'null' string for undefined CID (got %q)", string(enc))
+	}
 }
 
 func BenchmarkStringV1(b *testing.B) {
@@ -588,6 +695,52 @@ func TestReadCidsFromBuffer(t *testing.T) {
 	}
 }
 
+func TestBadCidFromBytes(t *testing.T) {
+	l, c, err := CidFromBytes([]byte{mh.SHA2_256, 32, 0x00})
+	if err == nil {
+		t.Fatal("expected not-enough-bytes for V0 CidFromBytes")
+	}
+	if l != 0 {
+		t.Fatal("expected length=0 from bad CidFromBytes")
+	}
+	if c != Undef {
+		t.Fatal("expected Undef CID from bad CidFromBytes")
+	}
+
+	c, err = Decode("bafkreie5qrjvaw64n4tjm6hbnm7fnqvcssfed4whsjqxzslbd3jwhsk3mm")
+	if err != nil {
+		t.Fatal(err)
+	}
+	byts := make([]byte, c.ByteLen())
+	copy(byts, c.Bytes())
+	byts[1] = 0x80 // bad codec varint
+	byts[2] = 0x00
+	l, c, err = CidFromBytes(byts)
+	if err == nil {
+		t.Fatal("expected not-enough-bytes for V1 CidFromBytes")
+	}
+	if l != 0 {
+		t.Fatal("expected length=0 from bad CidFromBytes")
+	}
+	if c != Undef {
+		t.Fatal("expected Undef CID from bad CidFromBytes")
+	}
+
+	copy(byts, c.Bytes())
+	byts[2] = 0x80 // bad multihash varint
+	byts[3] = 0x00
+	l, c, err = CidFromBytes(byts)
+	if err == nil {
+		t.Fatal("expected not-enough-bytes for V1 CidFromBytes")
+	}
+	if l != 0 {
+		t.Fatal("expected length=0 from bad CidFromBytes")
+	}
+	if c != Undef {
+		t.Fatal("expected Undef CID from bad CidFromBytes")
+	}
+}
+
 func TestBadParse(t *testing.T) {
 	hash, err := mh.Sum([]byte("foobar"), mh.SHA3_256, -1)
 	if err != nil {
@@ -598,3 +751,16 @@ func TestBadParse(t *testing.T) {
 		t.Fatal("expected to fail to parse an invalid CIDv1 CID")
 	}
 }
+
+func TestLoggable(t *testing.T) {
+	c, err := Decode("bafkreie5qrjvaw64n4tjm6hbnm7fnqvcssfed4whsjqxzslbd3jwhsk3mm")
+	if err != nil {
+		t.Fatal(err)
+	}
+	actual := c.Loggable()
+	expected := make(map[string]interface{})
+	expected["cid"] = c
+	if !reflect.DeepEqual(actual, expected) {
+		t.Fatalf("did not get expected loggable form (got %v)", actual)
+	}
+}

go.mod

@@ -2,8 +2,8 @@ module github.com/ipfs/go-cid
 
 require (
 	github.com/multiformats/go-multibase v0.0.3
-	github.com/multiformats/go-multihash v0.0.13
-	github.com/multiformats/go-varint v0.0.5
+	github.com/multiformats/go-multihash v0.0.16-0.20210406191223-75ae3688857d
+	github.com/multiformats/go-varint v0.0.6
 )
 
-go 1.13
+go 1.15

go.sum

@@ -1,28 +1,29 @@
+github.com/klauspost/cpuid/v2 v2.0.4 h1:g0I61F2K2DjRHz1cnxlkNSBIaePVoJIjjnHui8QHbiw=
+github.com/klauspost/cpuid/v2 v2.0.4/go.mod h1:FInQzS24/EEf25PyTYn52gqo7WaD8xa0213Md/qVLRg=
 github.com/minio/blake2b-simd v0.0.0-20160723061019-3f5f724cb5b1 h1:lYpkrQH5ajf0OXOcUbGjvZxxijuBwbbmlSxLiuofa+g=
 github.com/minio/blake2b-simd v0.0.0-20160723061019-3f5f724cb5b1/go.mod h1:pD8RvIylQ358TN4wwqatJ8rNavkEINozVn9DtGI3dfQ=
-github.com/minio/sha256-simd v0.1.1-0.20190913151208-6de447530771 h1:MHkK1uRtFbVqvAgvWxafZe54+5uBxLluGylDiKgdhwo=
-github.com/minio/sha256-simd v0.1.1-0.20190913151208-6de447530771/go.mod h1:B5e1o+1/KgNmWrSQK08Y6Z1Vb5pwIktudl0J58iy0KM=
-github.com/mr-tron/base58 v1.1.0 h1:Y51FGVJ91WBqCEabAi5OPUz38eAx8DakuAm5svLcsfQ=
+github.com/minio/sha256-simd v1.0.0 h1:v1ta+49hkWZyvaKwrQB8elexRqm6Y0aMLjCNsrYxo6g=
+github.com/minio/sha256-simd v1.0.0/go.mod h1:OuYzVNI5vcoYIAmbIvHPl3N3jUzVedXbKy5RFepssQM=
 github.com/mr-tron/base58 v1.1.0/go.mod h1:xcD2VGqlgYjBdcBLw+TuYLr8afG+Hj8g2eTVqeSzSU8=
-github.com/mr-tron/base58 v1.1.3 h1:v+sk57XuaCKGXpWtVBX8YJzO7hMGx4Aajh4TQbdEFdc=
-github.com/mr-tron/base58 v1.1.3/go.mod h1:BinMc/sQntlIE1frQmRFPUoPA1Zkr8VRgBdjWI2mNwc=
+github.com/mr-tron/base58 v1.2.0 h1:T/HDJBh4ZCPbU39/+c3rRvE0uKBQlU27+QI8LJ4t64o=
+github.com/mr-tron/base58 v1.2.0/go.mod h1:BinMc/sQntlIE1frQmRFPUoPA1Zkr8VRgBdjWI2mNwc=
 github.com/multiformats/go-base32 v0.0.3 h1:tw5+NhuwaOjJCC5Pp82QuXbrmLzWg7uxlMFp8Nq/kkI=
 github.com/multiformats/go-base32 v0.0.3/go.mod h1:pLiuGC8y0QR3Ue4Zug5UzK9LjgbkL8NSQj0zQ5Nz/AA=
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 github.com/multiformats/go-base36 v0.1.0/go.mod h1:kFGE83c6s80PklsHO9sRn2NCoffoRdUUOENyW/Vv6sM=
 github.com/multiformats/go-multibase v0.0.3 h1:l/B6bJDQjvQ5G52jw4QGSYeOTZoAwIO77RblWplfIqk=
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-github.com/multiformats/go-multihash v0.0.13 h1:06x+mk/zj1FoMsgNejLpy6QTvJqlSt/BhLEy87zidlc=
-github.com/multiformats/go-multihash v0.0.13/go.mod h1:VdAWLKTwram9oKAatUcLxBNUjdtcVwxObEQBtRfuyjc=
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-github.com/multiformats/go-varint v0.0.5/go.mod h1:3Ls8CIEsrijN6+B7PbrXRPxHRPuXSrVKRY101jdMZYE=
-github.com/spaolacci/murmur3 v1.1.0 h1:7c1g84S4BPRrfL5Xrdp6fOJ206sU9y293DDHaoy0bLI=
-github.com/spaolacci/murmur3 v1.1.0/go.mod h1:JwIasOWyU6f++ZhiEuf87xNszmSA2myDM2Kzu9HwQUA=
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+golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=
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varint.go

@@ -4,7 +4,7 @@ import (
 	"github.com/multiformats/go-varint"
 )
 
-// Version of varint function that work with a string rather than
+// Version of varint function that works with a string rather than
 // []byte to avoid unnecessary allocation
 
 // Copyright 2011 The Go Authors. All rights reserved.
@@ -12,23 +12,20 @@ import (
 // license as given at https://golang.org/LICENSE
 
 // uvarint decodes a uint64 from buf and returns that value and the
-// number of characters read (> 0). If an error occurred, the value is 0
-// and the number of bytes n is <= 0 meaning:
-//
-// 	n == 0: buf too small
-// 	n  < 0: value larger than 64 bits (overflow)
-// 	        and -n is the number of bytes read
-//
+// number of bytes read (> 0). If an error occurred, then 0 is
+// returned for both the value and the number of bytes read, and an
+// error is returned.
 func uvarint(buf string) (uint64, int, error) {
 	var x uint64
 	var s uint
-	// we have a binary string so we can't use a range loope
+	// we have a binary string so we can't use a range loop
 	for i := 0; i < len(buf); i++ {
 		b := buf[i]
 		if b < 0x80 {
 			if i > 9 || i == 9 && b > 1 {
 				return 0, 0, varint.ErrOverflow
-			} else if b == 0 && i > 0 {
+			}
+			if b == 0 && i > 0 {
 				return 0, 0, varint.ErrNotMinimal
 			}
 			return x | uint64(b)<<s, i + 1, nil

varint_test.go

@@ -28,3 +28,29 @@ func TestUvarintRoundTrip(t *testing.T) {
 		}
 	}
 }
+
+func TestUvarintEdges(t *testing.T) {
+	tests := []struct {
+		name  string
+		input []byte
+		want  error
+	}{
+		{"ErrNotMinimal", []byte{0x01 | 0x80, 0}, varint.ErrNotMinimal},
+		{"ErrOverflow", []byte{0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x01}, varint.ErrOverflow},
+		{"ErrUnderflow", []byte{0x80}, varint.ErrUnderflow},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			v, l1, err := uvarint(string(test.input))
+			if err != test.want {
+				t.Fatalf("error case (%v) should return varint.%s (got: %v)", test.input, test.name, err)
+			}
+			if v != 0 {
+				t.Fatalf("error case (%v) should return 0 value (got %d)", test.input, v)
+			}
+			if l1 != 0 {
+				t.Fatalf("error case (%v) should return 0 length (got %d)", test.input, l1)
+			}
+		})
+	}
+}