optimize checksum calculation

Author: alessio-perugini

v2/pkgs/tools.go

@@ -16,7 +16,6 @@
 package pkgs
 
 import (
-	"bytes"
 	"context"
 	"crypto/sha256"
 	"encoding/hex"
@@ -195,21 +194,8 @@ func (t *Tools) install(ctx context.Context, path, url, checksum string) (*tools
 	}
 	defer res.Body.Close()
 
-	var buffer bytes.Buffer
-
-	// We copy the body of the response to a buffer to calculate the checksum
-	_, err = io.Copy(&buffer, res.Body)
-	if err != nil {
-		return nil, err
-	}
-
-	// Check the checksum
-	sum := sha256.Sum256(buffer.Bytes())
-	sumString := "SHA-256:" + hex.EncodeToString(sum[:sha256.Size])
-
-	if sumString != checksum {
-		return nil, errors.New("checksum of downloaded file doesn't match, expected: " + checksum + " got: " + sumString)
-	}
+	h := sha256.New()
+	r := io.TeeReader(res.Body, h)
 
 	safePath, err := utilities.SafeJoin(t.folder, path)
 	if err != nil {
@@ -222,12 +208,18 @@ func (t *Tools) install(ctx context.Context, path, url, checksum string) (*tools
 		return nil, err
 	}
 
-	err = extract.Archive(ctx, &buffer, t.folder, rename(path))
+	err = extract.Archive(ctx, r, t.folder, rename(path))
 	if err != nil {
 		os.RemoveAll(safePath)
 		return nil, err
 	}
 
+	// Check the checksum
+	sumString := "SHA-256:" + hex.EncodeToString(h.Sum(nil))
+	if sumString != checksum {
+		return nil, errors.New("checksum of downloaded file doesn't match, expected: " + checksum + " got: " + sumString)
+	}
+
 	// Write installed.json for retrocompatibility with v1
 	err = writeInstalled(t.folder, path)
 	if err != nil {