[FILEUPLOAD-258] Empty files in mutipart requests aren't saved to disk

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.3, 1.3.1
• Fix Version/s: 1.4
• Assignee: Unassigned
• Reporter: Peter Cowan
• Created: 15/Sep/14 11:25
• Updated: 05/Feb/19 14:11
• Resolved: 11/Nov/14 20:42

Description

If a multipart request contains an empty file, ServletFileUpload#parseRequest does not create a corresponding temporary file on the file system. If any operations are performed on the corresponding file object from DiskFileItem#getStoreLocation() a FileNotFoundException is thrown.

FileUploadBase#parseRequest() copies the multipart file input stream to the temporary file output stream with Streams#copy(). This method only creates the temporary file on the file system if data is written to the file's output stream. Since the input stream is empty, write is never called on the output stream and the temporary file is not created.

I've used the following snippet to overcome this issue. This ensures the temporary file is created on the file system prior to writing:

Snippet.java

final DiskFileItemFactory factory = new DiskFileItemFactory() {
  @Override
  public FileItem createItem(final String fieldName, final String contentType, final boolean isFormField, final String fileName) {
    return new DiskFileItem(fieldName, contentType, isFormField, fileName, getSizeThreshold(), getRepository()) {
      private static final long serialVersionUID = 1L;

      @Override
      protected File getTempFile() {
        File tempFile = super.getTempFile();
        try {
          tempFile.createNewFile();
        }
        catch (final IOException e) {
          //Handle appropriately
          ...
        }
        return tempFile;
      }
    };
  }
};

ServletFileUpload upload = new ServletFileUpload(factory);