use buffer as temp instead of file

core/file.go

@@ -47,25 +47,9 @@ func init() {
 func ProcessFile(ctx context.Context, path string, transform func(io.Reader, io.Writer) error) error {
 	logger := logr.FromContextOrDiscard(ctx)
 	logger = logger.WithValues("file", path)
-	logger.Info("Processing file")
+	logger.V(1).Info("Processing file")
 
-	originalFile, err := os.OpenFile(path, os.O_RDWR, 0o644)
-	if err != nil {
-		return fmt.Errorf("failed to open original file: %w", err)
-	}
-	defer func() {
-		if err := unlockFile(originalFile); err != nil {
-			logger.Error(err, "Failed to unlock file")
-		}
-		originalFile.Close()
-	}()
-
-	err = lockFile(originalFile)
-	if err != nil {
-		return err
-	}
-
-	originalContent, err := io.ReadAll(originalFile)
+	originalContent, err := os.ReadFile(path)
 	if err != nil {
 		return fmt.Errorf("failed to read original file: %w", err)
 	}
@@ -77,31 +61,37 @@ func ProcessFile(ctx context.Context, path string, transform func(io.Reader, io.
 	}
 
 	if bytes.Equal(originalContent, processedContent.Bytes()) {
-		logger.Info("File content unchanged, skipping write")
+		logger.V(1).Info("File content unchanged, skipping write")
 		return nil
 	}
 
-	_, err = originalFile.Seek(0, 0)
+	originalFile, err := os.OpenFile(path, os.O_RDWR|os.O_TRUNC, 0o644)
 	if err != nil {
-		return fmt.Errorf("failed to seek to the beginning of original file: %w", err)
+		return fmt.Errorf("failed to open original file: %w", err)
 	}
+	defer func() {
+		if err := unlockFile(originalFile); err != nil {
+			logger.Error(err, "Failed to unlock file")
+		}
+		originalFile.Close()
+	}()
 
-	err = originalFile.Truncate(0)
+	err = lockFile(originalFile)
 	if err != nil {
-		return fmt.Errorf("failed to truncate original file: %w", err)
+		return err
 	}
 
-	_, err = io.Copy(originalFile, &processedContent)
+	_, err = originalFile.Write(processedContent.Bytes())
 	if err != nil {
 		return fmt.Errorf("failed to write processed content to file: %w", err)
 	}
 
 	err = originalFile.Sync()
 	if err != nil {
-		return fmt.Errorf("failed to sync file: %w", err)
+		return fmt.Errorf("failed to s.V(1)ync file: %w", err)
 	}
 
-	logger.Info("Successfully processed and updated file")
+	logger.V(1).Info("Successfully processed and updated file")
 	return nil
 }