Update upgrade.go

cli/cage/upgrade/upgrade.go

@@ -74,7 +74,7 @@ func (u *upgrader) Upgrade(p *Input) error {
 		return err
 	}
 	log.Infof("downloading binary %s...", binaryAsset.GetName())
-	cageRd, err := unzipArchive(binaryAsset.GetBrowserDownloadURL(), checksum)
+	newCageFile, err := unzipArchive(binaryAsset.GetBrowserDownloadURL(), checksum)
 	if err != nil {
 		return err
 	}
@@ -87,7 +87,7 @@ func (u *upgrader) Upgrade(p *Input) error {
 		}
 		targetPath = exec
 	}
-	if err := swapFiles(targetPath, cageRd); err != nil {
+	if err := swapFiles(targetPath, newCageFile); err != nil {
 		return err
 	}
 	log.Infof("upgraded to %s", version)
@@ -124,39 +124,48 @@ func (u *upgrader) FindLatestRelease(pre bool) (*github.RepositoryRelease, error
 func unzipArchive(
 	assetUrl string,
 	checksum []byte,
-) (io.ReadCloser, error) {
+) (string, error) {
 	resp, err := http.DefaultClient.Get(assetUrl)
 	if err != nil {
-		return nil, err
+		return "", err
 	}
 	defer resp.Body.Close()
 
 	zipdest, err := os.CreateTemp("", "cage")
 	if err != nil {
-		return nil, err
+		return "", err
 	}
 	defer zipdest.Close()
 
 	sha := sha256.New()
 	if _, err := io.Copy(zipdest, io.TeeReader(resp.Body, sha)); err != nil {
-		return nil, err
+		return "", err
 	}
 
 	actChecksum := sha.Sum(nil)
 	if !bytes.Equal(checksum, actChecksum) {
-		return nil, xerrors.Errorf("checksum mismatch: expected %x, got %x", checksum, actChecksum)
+		return "", xerrors.Errorf("checksum mismatch: expected %x, got %x", checksum, actChecksum)
 	}
 
 	ziprd, err := zip.OpenReader(zipdest.Name())
 	if err != nil {
-		return nil, err
+		return "", err
 	}
 	defer ziprd.Close()
 	cageRd, err := ziprd.Open("cage")
 	if err != nil {
-		return nil, err
+		return "", err
 	}
-	return cageRd, nil
+	defer cageRd.Close()
+	cageDest, err := os.CreateTemp("", "cage")
+	if err != nil {
+		return "", err
+	}
+	defer cageDest.Close()
+	if _, err := io.Copy(cageDest, cageRd); err != nil {
+		return "", err
+	}
+	return cageDest.Name(), nil
 }
 
 func parseChecksums(url string, file string) ([]byte, error) {
@@ -195,20 +204,12 @@ func parseChecksums(url string, file string) ([]byte, error) {
 
 func swapFiles(
 	targetPath string,
-	newReader io.ReadCloser,
+	newPath string,
 ) error {
-	defer newReader.Close()
-	// Write to a new file
 	newFilepath := targetPath + ".new"
-	newFile, err := os.OpenFile(newFilepath, os.O_CREATE|os.O_WRONLY, 0755)
-	if err != nil {
-		return err
-	}
-	defer newFile.Close()
-	if _, err := io.Copy(newFile, newReader); err != nil {
+	if err := os.Rename(newPath, newFilepath); err != nil {
 		return err
 	}
-	// Swap files
 	oldFilepath := targetPath + ".old"
 	if err := os.Rename(targetPath, oldFilepath); err != nil {
 		return err