Introduced sha256 support for git-sizer

git/git.go

@@ -19,7 +19,8 @@ type Repository struct {
 
 	// gitBin is the path of the `git` executable that should be used
 	// when running commands in this repository.
-	gitBin string
+	gitBin   string
+	hashAlgo HashAlgo
 }
 
 // smartJoin returns the path that can be described as `relPath`
@@ -77,10 +78,18 @@ func NewRepository(path string) (*Repository, error) {
 	if err == nil {
 		return nil, errors.New("this appears to be a shallow clone; full clone required")
 	}
+	hashAlgo := HashSHA1
+	cmd = exec.Command(gitBin, "rev-parse", "--show-object-format")
+	if out, err = cmd.Output(); err == nil {
+		if string(bytes.TrimSpace(out)) == "sha256" {
+			hashAlgo = HashSHA256
+		}
+	}
 
 	return &Repository{
-		path:   gitDir,
-		gitBin: gitBin,
+		path:     gitDir,
+		gitBin:   gitBin,
+		hashAlgo: hashAlgo,
 	}, nil
 }
 
@@ -115,3 +124,11 @@ func (repo *Repository) GitCommand(callerArgs ...string) *exec.Cmd {
 func (repo *Repository) Path() string {
 	return repo.path
 }
+
+func (repo *Repository) HashAlgo() HashAlgo {
+	return repo.hashAlgo
+}
+
+func (repo *Repository) HashSize() int {
+	return repo.hashAlgo.HashSize()
+}

git/obj_iter.go

@@ -30,7 +30,7 @@ func (repo *Repository) NewObjectIter(ctx context.Context) (*ObjectIter, error)
 		errCh:    make(chan error),
 		headerCh: make(chan BatchHeader),
 	}
-
+	hashSize := repo.HashSize()
 	iter.p.Add(
 		// Read OIDs from `iter.oidCh` and write them to `git
 		// rev-list`:
@@ -68,10 +68,10 @@ func (repo *Repository) NewObjectIter(ctx context.Context) (*ObjectIter, error)
 		pipe.LinewiseFunction(
 			"copy-oids",
 			func(_ context.Context, _ pipe.Env, line []byte, stdout *bufio.Writer) error {
-				if len(line) < 40 {
+				if len(line) < hashSize {
 					return fmt.Errorf("line too short: '%s'", line)
 				}
-				if _, err := stdout.Write(line[:40]); err != nil {
+				if _, err := stdout.Write(line[:hashSize]); err != nil {
 					return fmt.Errorf("writing OID to 'git cat-file': %w", err)
 				}
 				if err := stdout.WriteByte('\n'); err != nil {

git/oid.go

@@ -1,31 +1,75 @@
 package git
 
 import (
+	"bytes"
+	"crypto/sha1"
+	"crypto/sha256"
 	"encoding/hex"
 	"errors"
 )
 
+const (
+	HashSizeSHA256 = sha256.Size
+	HashSizeSHA1   = sha1.Size
+	HashSizeMax    = HashSizeSHA256
+)
+
+type HashAlgo int
+
+const (
+	HashUnknown HashAlgo = iota
+	HashSHA1
+	HashSHA256
+)
+
 // OID represents the SHA-1 object ID of a Git object, in binary
 // format.
 type OID struct {
-	v [20]byte
+	v        [HashSizeMax]byte
+	hashSize int
 }
 
-// NullOID is the null object ID; i.e., all zeros.
-var NullOID OID
+func (h HashAlgo) NullOID() OID {
+	switch h {
+	case HashSHA1:
+		return OID{hashSize: HashSizeSHA1}
+	case HashSHA256:
+		return OID{hashSize: HashSizeSHA256}
+	}
+	return OID{}
+}
+
+func (h HashAlgo) HashSize() int {
+	switch h {
+	case HashSHA1:
+		return HashSizeSHA1
+	case HashSHA256:
+		return HashSizeSHA256
+	}
+	return 0
+}
+
+// defaultNullOID is the null object ID; i.e., all zeros.
+var defaultNullOID OID
+
+func IsNullOID(o OID) bool {
+	return bytes.Equal(o.v[:], defaultNullOID.v[:])
+}
 
 // OIDFromBytes converts a byte slice containing an object ID in
 // binary format into an `OID`.
 func OIDFromBytes(oidBytes []byte) (OID, error) {
 	var oid OID
-	if len(oidBytes) != len(oid.v) {
+	oidSize := len(oidBytes)
+	if oidSize != HashSizeSHA1 && oidSize != HashSizeSHA256 {
 		return OID{}, errors.New("bytes oid has the wrong length")
 	}
-	copy(oid.v[0:20], oidBytes)
+	oid.hashSize = oidSize
+	copy(oid.v[0:oidSize], oidBytes)
 	return oid, nil
 }
 
-// NewOID converts an object ID in hex format (i.e., `[0-9a-f]{40}`)
+// NewOID converts an object ID in hex format (i.e., `[0-9a-f]{40,32}`)
 // into an `OID`.
 func NewOID(s string) (OID, error) {
 	oidBytes, err := hex.DecodeString(s)
@@ -37,18 +81,18 @@ func NewOID(s string) (OID, error) {
 
 // String formats `oid` as a string in hex format.
 func (oid OID) String() string {
-	return hex.EncodeToString(oid.v[:])
+	return hex.EncodeToString(oid.v[:oid.hashSize])
 }
 
 // Bytes returns a byte slice view of `oid`, in binary format.
 func (oid OID) Bytes() []byte {
-	return oid.v[:]
+	return oid.v[:oid.hashSize]
 }
 
 // MarshalJSON expresses `oid` as a JSON string with its enclosing
 // quotation marks.
 func (oid OID) MarshalJSON() ([]byte, error) {
-	src := oid.v[:]
+	src := oid.v[:oid.hashSize]
 	dst := make([]byte, hex.EncodedLen(len(src))+2)
 	dst[0] = '"'
 	dst[len(dst)-1] = '"'

git/ref_filter.go

@@ -36,14 +36,14 @@ func (f intersection) Filter(refname string) bool {
 // If `f1` is `nil`, it is treated as including nothing.
 type include struct{}
 
-func (_ include) Combine(f1, f2 ReferenceFilter) ReferenceFilter {
+func (include) Combine(f1, f2 ReferenceFilter) ReferenceFilter {
 	if f1 == nil {
 		return f2
 	}
 	return union{f1, f2}
 }
 
-func (_ include) Inverted() Combiner {
+func (include) Inverted() Combiner {
 	return Exclude
 }
 
@@ -61,23 +61,23 @@ func (f union) Filter(refname string) bool {
 // If `f1` is `nil`, it is treated as including everything.
 type exclude struct{}
 
-func (_ exclude) Combine(f1, f2 ReferenceFilter) ReferenceFilter {
+func (exclude) Combine(f1, f2 ReferenceFilter) ReferenceFilter {
 	if f1 == nil {
 		return inverse{f2}
 	}
 	return intersection{f1, inverse{f2}}
 
 }
 
-func (_ exclude) Inverted() Combiner {
+func (exclude) Inverted() Combiner {
 	return include{}
 }
 
 var Exclude exclude
 
 type allReferencesFilter struct{}
 
-func (_ allReferencesFilter) Filter(_ string) bool {
+func (allReferencesFilter) Filter(_ string) bool {
 	return true
 }
 
@@ -87,11 +87,11 @@ var AllReferencesFilter allReferencesFilter
 // whose names start with the specified `prefix`, which must match at
 // a component boundary. For example,
 //
-// * Prefix "refs/foo" matches "refs/foo" and "refs/foo/bar" but not
-//   "refs/foobar".
+//   - Prefix "refs/foo" matches "refs/foo" and "refs/foo/bar" but not
+//     "refs/foobar".
 //
-// * Prefix "refs/foo/" matches "refs/foo/bar" but not "refs/foo" or
-//   "refs/foobar".
+//   - Prefix "refs/foo/" matches "refs/foo/bar" but not "refs/foo" or
+//     "refs/foobar".
 func PrefixFilter(prefix string) ReferenceFilter {
 	if prefix == "" {
 		return AllReferencesFilter

git/tree.go

@@ -10,13 +10,14 @@ import (
 
 // Tree represents a Git tree object.
 type Tree struct {
-	data string
+	data     string
+	hashSize int
 }
 
 // ParseTree parses the tree object whose contents are contained in
 // `data`. `oid` is currently unused.
 func ParseTree(oid OID, data []byte) (*Tree, error) {
-	return &Tree{string(data)}, nil
+	return &Tree{string(data), oid.hashSize}, nil
 }
 
 // Size returns the size of the tree object.
@@ -36,13 +37,15 @@ type TreeEntry struct {
 // TreeIter is an iterator over the entries in a Git tree object.
 type TreeIter struct {
 	// The as-yet-unread part of the tree's data.
-	data string
+	data     string
+	hashSize int
 }
 
 // Iter returns an iterator over the entries in `tree`.
 func (tree *Tree) Iter() *TreeIter {
 	return &TreeIter{
-		data: tree.data,
+		data:     tree.data,
+		hashSize: tree.hashSize,
 	}
 }
 
@@ -74,12 +77,12 @@ func (iter *TreeIter) NextEntry() (TreeEntry, bool, error) {
 	entry.Name = iter.data[:nulAt]
 
 	iter.data = iter.data[nulAt+1:]
-	if len(iter.data) < 20 {
+	if len(iter.data) < iter.hashSize {
 		return TreeEntry{}, false, errors.New("tree entry ends unexpectedly")
 	}
-
-	copy(entry.OID.v[0:20], iter.data[0:20])
-	iter.data = iter.data[20:]
+	entry.OID.hashSize = iter.hashSize
+	copy(entry.OID.v[0:iter.hashSize], iter.data[0:iter.hashSize])
+	iter.data = iter.data[iter.hashSize:]
 
 	return entry, true, nil
 }

go.mod

@@ -3,18 +3,17 @@ module github.com/github/git-sizer
 go 1.17
 
 require (
-	github.com/cli/safeexec v1.0.0
-	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/cli/safeexec v1.0.1
+	github.com/github/go-pipe v1.0.2
 	github.com/spf13/pflag v1.0.5
-	github.com/stretchr/testify v1.8.1
-	golang.org/x/sync v0.1.0 // indirect
+	github.com/stretchr/testify v1.8.2
 )
 
-require github.com/github/go-pipe v1.0.2
-
 require (
-	github.com/kr/pretty v0.1.0 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/kr/pretty v0.3.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
+	golang.org/x/sync v0.1.0 // indirect
+	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -1,28 +1,34 @@
-github.com/cli/safeexec v1.0.0 h1:0VngyaIyqACHdcMNWfo6+KdUYnqEr2Sg+bSP1pdF+dI=
-github.com/cli/safeexec v1.0.0/go.mod h1:Z/D4tTN8Vs5gXYHDCbaM1S/anmEDnJb1iW0+EJ5zx3Q=
+github.com/cli/safeexec v1.0.1 h1:e/C79PbXF4yYTN/wauC4tviMxEV13BwljGj0N9j+N00=
+github.com/cli/safeexec v1.0.1/go.mod h1:Z/D4tTN8Vs5gXYHDCbaM1S/anmEDnJb1iW0+EJ5zx3Q=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/github/go-pipe v1.0.2 h1:befTXflsc6ir/h9f6Q7QCDmfojoBswD1MfQrPhmmSoA=
 github.com/github/go-pipe v1.0.2/go.mod h1:/GvNLA516QlfGGMtfv4PC/5/CdzL9X4af/AJYhmLD54=
-github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
+github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
 github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
-github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
 github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+github.com/stretchr/testify v1.8.2 h1:+h33VjcLVPDHtOdpUCuF+7gSuG3yGIftsP1YvFihtJ8=
+github.com/stretchr/testify v1.8.2/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
 go.uber.org/goleak v1.2.0 h1:xqgm/S+aQvhWFTtR0XK3Jvg7z8kGV8P4X14IzwN3Eqk=
 go.uber.org/goleak v1.2.0/go.mod h1:XJYK+MuIchqpmGmUSAzotztawfKvYLUIgg7guXrwVUo=
@@ -54,8 +60,9 @@ golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8T
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/testutils/repoutils.go

@@ -158,7 +158,7 @@ func (repo *TestRepo) UpdateRef(t *testing.T, refname string, oid git.OID) {
 
 	var cmd *exec.Cmd
 
-	if oid == git.NullOID {
+	if git.IsNullOID(oid) {
 		cmd = repo.GitCommand(t, "update-ref", "-d", refname)
 	} else {
 		cmd = repo.GitCommand(t, "update-ref", refname, oid.String())

sizes/graph.go

@@ -68,7 +68,7 @@ func ScanRepositoryUsingGraph(
 ) (HistorySize, error) {
 	ctx, cancel := context.WithCancel(context.TODO())
 	defer cancel()
-
+	nullOID := repo.HashAlgo().NullOID()
 	graph := NewGraph(rg, nameStyle)
 
 	refIter, err := repo.NewReferenceIter(ctx)
@@ -190,7 +190,7 @@ func ScanRepositoryUsingGraph(
 		case "tree":
 			trees = append(trees, ObjectHeader{obj.OID, obj.ObjectSize})
 		case "commit":
-			commits = append(commits, CommitHeader{ObjectHeader{obj.OID, obj.ObjectSize}, git.NullOID})
+			commits = append(commits, CommitHeader{ObjectHeader{obj.OID, obj.ObjectSize}, nullOID})
 		case "tag":
 			tags = append(tags, ObjectHeader{obj.OID, obj.ObjectSize})
 		default: