hash: add CRC-32 support

fs/hash/hash.go

@@ -6,6 +6,7 @@ import (
 	"encoding/hex"
 	"fmt"
 	"hash"
+	"hash/crc32"
 	"io"
 	"strings"
 
@@ -40,13 +41,16 @@ const (
 	// Whirlpool indicates Whirlpool support
 	Whirlpool
 
+	// CRC32 indicates CRC-32 support
+	CRC32
+
 	// None indicates no hashes are supported
 	None Type = 0
 )
 
 // Supported returns a set of all the supported hashes by
 // HashStream and MultiHasher.
-var Supported = NewHashSet(MD5, SHA1, Dropbox, QuickXorHash, Whirlpool)
+var Supported = NewHashSet(MD5, SHA1, Dropbox, QuickXorHash, Whirlpool, CRC32)
 
 // Width returns the width in characters for any HashType
 var Width = map[Type]int{
@@ -55,6 +59,7 @@ var Width = map[Type]int{
 	Dropbox:      64,
 	QuickXorHash: 40,
 	Whirlpool:    128,
+	CRC32:        8,
 }
 
 // Stream will calculate hashes of all supported hash types.
@@ -96,6 +101,8 @@ func (h Type) String() string {
 		return "QuickXorHash"
 	case Whirlpool:
 		return "Whirlpool"
+	case CRC32:
+		return "CRC-32"
 	default:
 		err := fmt.Sprintf("internal error: unknown hash type: 0x%x", int(h))
 		panic(err)
@@ -117,6 +124,8 @@ func (h *Type) Set(s string) error {
 		*h = QuickXorHash
 	case "Whirlpool":
 		*h = Whirlpool
+	case "CRC-32":
+		*h = CRC32
 	default:
 		return errors.Errorf("Unknown hash type %q", s)
 	}
@@ -149,6 +158,8 @@ func fromTypes(set Set) (map[Type]hash.Hash, error) {
 			hashers[t] = quickxorhash.New()
 		case Whirlpool:
 			hashers[t] = whirlpool.New()
+		case CRC32:
+			hashers[t] = crc32.NewIEEE()
 		default:
 			err := fmt.Sprintf("internal error: Unsupported hash type %v", t)
 			panic(err)

fs/hash/hash_test.go

@@ -74,6 +74,7 @@ var hashTestSet = []hashTest{
 			hash.Dropbox:      "214d2fcf3566e94c99ad2f59bd993daca46d8521a0c447adf4b324f53fddc0c7",
 			hash.QuickXorHash: "0110c000085000031c0001095ec00218d0000700",
 			hash.Whirlpool:    "eddf52133d4566d763f716e853d6e4efbabd29e2c2e63f56747b1596172851d34c2df9944beb6640dbdbe3d9b4eb61180720a79e3d15baff31c91e43d63869a4",
+			hash.CRC32:        "a6041d7e",
 		},
 	},
 	// Empty data set
@@ -85,6 +86,7 @@ var hashTestSet = []hashTest{
 			hash.Dropbox:      "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
 			hash.QuickXorHash: "0000000000000000000000000000000000000000",
 			hash.Whirlpool:    "19fa61d75522a4669b44e39c1d2e1726c530232130d407f89afee0964997f7a73e83be698b288febcf88e3e03c4f0757ea8964e59b63d93708b138cc42a66eb3",
+			hash.CRC32:        "00000000",
 		},
 	},
 }