1 files changed, 61 insertions, 0 deletions

diff --git a/cli/internal/fs/hash.go b/cli/internal/fs/hash.go
new file mode 100644
index 0000000..fed7d87
--- /dev/null
+++ b/cli/internal/fs/hash.go
@@ -0,0 +1,61 @@
+package fs
+
+import (
+	"crypto/sha1"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+
+	"github.com/vercel/turbo/cli/internal/xxhash"
+)
+
+func HashObject(i interface{}) (string, error) {
+	hash := xxhash.New()
+
+	_, err := hash.Write([]byte(fmt.Sprintf("%v", i)))
+
+	return hex.EncodeToString(hash.Sum(nil)), err
+}
+
+func HashFile(filePath string) (string, error) {
+	file, err := os.Open(filePath)
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+
+	hash := xxhash.New()
+	if _, err := io.Copy(hash, file); err != nil {
+		return "", err
+	}
+
+	return hex.EncodeToString(hash.Sum(nil)), nil
+}
+
+// GitLikeHashFile is a function that mimics how Git
+// calculates the SHA1 for a file (or, in Git terms, a "blob") (without git)
+func GitLikeHashFile(filePath string) (string, error) {
+	file, err := os.Open(filePath)
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+
+	stat, err := file.Stat()
+	if err != nil {
+		return "", err
+	}
+	hash := sha1.New()
+	hash.Write([]byte("blob"))
+	hash.Write([]byte(" "))
+	hash.Write([]byte(strconv.FormatInt(stat.Size(), 10)))
+	hash.Write([]byte{0})
+
+	if _, err := io.Copy(hash, file); err != nil {
+		return "", err
+	}
+
+	return hex.EncodeToString(hash.Sum(nil)), nil
+}