plumbing: commitgraph, allow SHA256 commit-graphs

Since the build-tag sha256 was introduced the commit graph code should
be switched to use hash.Size and only use a graph if it has the correct
hash version for the version of go-git that is built.

Signed-off-by: Andrew Thornton <art27@cantab.net>

1 files changed, 7 insertions, 2 deletions

diff --git a/plumbing/format/commitgraph/encoder.go b/plumbing/format/commitgraph/encoder.go
index f61025b..674f52e 100644
--- a/plumbing/format/commitgraph/encoder.go
+++ b/plumbing/format/commitgraph/encoder.go
@@ -1,6 +1,7 @@
 package commitgraph

 

 import (

+	"crypto"

 	"io"

 

 	"github.com/go-git/go-git/v5/plumbing"

@@ -30,7 +31,7 @@ func (e *Encoder) Encode(idx Index) error {
 	hashToIndex, fanout, extraEdgesCount := e.prepare(idx, hashes)

 

 	chunkSignatures := [][]byte{oidFanoutSignature, oidLookupSignature, commitDataSignature}

-	chunkSizes := []uint64{4 * 256, uint64(len(hashes)) * hash.Size, uint64(len(hashes)) * 36}

+	chunkSizes := []uint64{4 * 256, uint64(len(hashes)) * hash.Size, uint64(len(hashes)) * (hash.Size + commitDataSize)}

 	if extraEdgesCount > 0 {

 		chunkSignatures = append(chunkSignatures, extraEdgeListSignature)

 		chunkSizes = append(chunkSizes, uint64(extraEdgesCount)*4)

@@ -88,7 +89,11 @@ func (e *Encoder) prepare(idx Index, hashes []plumbing.Hash) (hashToIndex map[pl
 

 func (e *Encoder) encodeFileHeader(chunkCount int) (err error) {

 	if _, err = e.Write(commitFileSignature); err == nil {

-		_, err = e.Write([]byte{1, 1, byte(chunkCount), 0})

+		version := byte(1)

+		if hash.CryptoType == crypto.SHA256 {

+			version = byte(2)

+		}

+		_, err = e.Write([]byte{1, version, byte(chunkCount), 0})

 	}

 	return

 }