Add MD5 checksum functions

Author: Arthur White

hash.go

@@ -0,0 +1,27 @@
+package crypto
+
+import (
+	"crypto/md5"
+	"fmt"
+	"io"
+	"os"
+)
+
+// HashMD5 returns the MD5 checksum of source.
+func HashMD5(src io.Reader) (string, error) {
+	h := md5.New()
+	if _, err := io.Copy(h, src); err != nil {
+		return "", nil
+	}
+	return fmt.Sprintf("%x", h.Sum(nil)), nil
+}
+
+// HashFileMD5 returns the MD5 checksum of a file.
+func HashFileMD5(path string) (string, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+	return HashMD5(f)
+}

hash_test.go

@@ -0,0 +1,26 @@
+package crypto
+
+import (
+	"os"
+	"testing"
+)
+
+var testsHashFile = []struct {
+	path string
+	want string
+}{
+	{"LICENSE", "edbc4f9728a8e311b55e081b27e3caff"},
+	{"unknown", ""},
+}
+
+func TestHashFileMD5(t *testing.T) {
+	for _, tt := range testsHashFile {
+		got, err := HashFileMD5(tt.path)
+		if err != nil && !os.IsNotExist(err) {
+			panic(err)
+		}
+		if got != tt.want {
+			t.Errorf("%q: want %q, got %q", tt.path, tt.want, got)
+		}
+	}
+}