*: Support variable length plumbing.Hash

The variable length for plumbing.Hash is defined at build time, blocked by
tag sha256.

This approach was a trade-off between keeping backwards compatibility while
making progress towards supporting SHA256 with a small amount of changes.

Relates to the SHA256 implementation, defined in #706.

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

1 files changed, 7 insertions, 7 deletions

diff --git a/plumbing/hash.go b/plumbing/hash.go
index 2fab759..39bb73f 100644
--- a/plumbing/hash.go
+++ b/plumbing/hash.go
@@ -2,7 +2,6 @@ package plumbing
 
 import (
 	"bytes"
-	"crypto"
 	"encoding/hex"
 	"sort"
 	"strconv"
@@ -11,7 +10,7 @@ import (
 )
 
 // Hash SHA1 hashed content
-type Hash [20]byte
+type Hash [hash.Size]byte
 
 // ZeroHash is Hash with value zero
 var ZeroHash Hash
@@ -47,7 +46,7 @@ type Hasher struct {
 }
 
 func NewHasher(t ObjectType, size int64) Hasher {
-	h := Hasher{hash.New(crypto.SHA1)}
+	h := Hasher{hash.New(hash.CryptoType)}
 	h.Write(t.Bytes())
 	h.Write([]byte(" "))
 	h.Write([]byte(strconv.FormatInt(size, 10)))
@@ -75,10 +74,11 @@ func (p HashSlice) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
 
 // IsHash returns true if the given string is a valid hash.
 func IsHash(s string) bool {
-	if len(s) != 40 {
+	switch len(s) {
+	case hash.HexSize:
+		_, err := hex.DecodeString(s)
+		return err == nil
+	default:
 		return false
 	}
-
-	_, err := hex.DecodeString(s)
-	return err == nil
 }