Final fix for writeheader

pkg/webdav/file.go

@@ -124,6 +124,7 @@ func (f *File) servePreloadedContent(w http.ResponseWriter, r *http.Request) err
 		w.Header().Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", start, end, size))
 		w.Header().Set("Content-Length", fmt.Sprintf("%d", end-start+1))
 		w.Header().Set("Accept-Ranges", "bytes")
+		w.WriteHeader(http.StatusPartialContent)
 
 		_, err = w.Write(content[start : end+1])
 		return err
@@ -132,6 +133,7 @@ func (f *File) servePreloadedContent(w http.ResponseWriter, r *http.Request) err
 	// Full content
 	w.Header().Set("Content-Length", fmt.Sprintf("%d", size))
 	w.Header().Set("Accept-Ranges", "bytes")
+	w.WriteHeader(http.StatusOK)
 
 	_, err := w.Write(content)
 	return err
@@ -195,9 +197,13 @@ func (f *File) streamWithRetry(w http.ResponseWriter, r *http.Request, retryCoun
 		return retryErr
 	}
 
-	if err := f.streamBuffer(w, resp.Body); err != nil {
-		return err
+	// Determine status code based on range request
+	statusCode := http.StatusOK
+	if isRangeRequest == 1 {
+		statusCode = http.StatusPartialContent
 	}
+
+	// Set headers before streaming
 	if contentLength := resp.Header.Get("Content-Length"); contentLength != "" {
 		w.Header().Set("Content-Length", contentLength)
 	}
@@ -205,10 +211,14 @@ func (f *File) streamWithRetry(w http.ResponseWriter, r *http.Request, retryCoun
 	if contentRange := resp.Header.Get("Content-Range"); contentRange != "" && isRangeRequest == 1 {
 		w.Header().Set("Content-Range", contentRange)
 	}
+
+	if err := f.streamBuffer(w, resp.Body, statusCode); err != nil {
+		return err
+	}
 	return nil
 }
 
-func (f *File) streamBuffer(w http.ResponseWriter, src io.Reader) error {
+func (f *File) streamBuffer(w http.ResponseWriter, src io.Reader, statusCode int) error {
 	flusher, ok := w.(http.Flusher)
 	if !ok {
 		return fmt.Errorf("response does not support flushing")
@@ -216,12 +226,19 @@ func (f *File) streamBuffer(w http.ResponseWriter, src io.Reader) error {
 
 	smallBuf := make([]byte, 64*1024) // 64 KB
 	if n, err := src.Read(smallBuf); n > 0 {
+		// Write status code just before first successful write
+		w.WriteHeader(statusCode)
+		
 		if _, werr := w.Write(smallBuf[:n]); werr != nil {
-			return werr
+			if isClientDisconnection(werr) {
+				return &streamError{Err: werr, StatusCode: 0, IsClientDisconnection: true}
+			}
+			// Headers already sent, can't send HTTP error response
+			return &streamError{Err: werr, StatusCode: 0, IsClientDisconnection: false}
 		}
 		flusher.Flush()
 	} else if err != nil && err != io.EOF {
-		return err
+		return &streamError{Err: err, StatusCode: http.StatusInternalServerError}
 	}
 
 	buf := make([]byte, 256*1024) // 256 KB
@@ -232,7 +249,8 @@ func (f *File) streamBuffer(w http.ResponseWriter, src io.Reader) error {
 				if isClientDisconnection(writeErr) {
 					return &streamError{Err: writeErr, StatusCode: 0, IsClientDisconnection: true}
 				}
-				return writeErr
+				// Headers already sent, can't send HTTP error response
+				return &streamError{Err: writeErr, StatusCode: 0, IsClientDisconnection: false}
 			}
 			flusher.Flush()
 		}

pkg/webdav/handler.go

@@ -463,16 +463,6 @@ func (h *Handler) handleGet(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 
-		// Check if this will be a range request before streaming
-		isRangeRequest := r.Header.Get("Range") != ""
-
-		// Write status headers before streaming starts
-		if isRangeRequest {
-			w.WriteHeader(http.StatusPartialContent)
-		} else {
-			w.WriteHeader(http.StatusOK)
-		}
-
 		if err := file.StreamResponse(w, r); err != nil {
 			var streamErr *streamError
 			if errors.As(err, &streamErr) {
@@ -480,12 +470,17 @@ func (h *Handler) handleGet(w http.ResponseWriter, r *http.Request) {
 				if errors.Is(streamErr.Err, context.Canceled) || errors.Is(streamErr.Err, context.DeadlineExceeded) || streamErr.IsClientDisconnection {
 					return
 				}
-				// For other errors, we can't send HTTP error response since headers are already written
-				h.logger.Error().Err(streamErr.Err).Str("file", file.name).Msg("Stream error after headers written")
-				return
+				if streamErr.StatusCode > 0 {
+					http.Error(w, streamErr.Error(), streamErr.StatusCode)
+					return
+				} else {
+					// We've already written a status code, just log the error
+					h.logger.Error().Err(streamErr.Err).Msg("Streaming error")
+					return
+				}
 			} else {
-				// Generic error - can't send HTTP error response since headers are already written
-				h.logger.Error().Err(err).Str("file", file.name).Msg("Generic stream error after headers written")
+				// Generic error
+				http.Error(w, "Internal Server Error", http.StatusInternalServerError)
 				return
 			}
 		}