paperclip/lib/paperclip/iostream.rb

# frozen_string_literal: true

# Provides method that can be included on File-type objects (IO, StringIO, Tempfile, etc) to allow stream copying
# and Tempfile conversion.
module IOStream
  # Returns a Tempfile containing the contents of the readable object.
  def to_tempfile(object)
    return object.to_tempfile if object.respond_to?(:to_tempfile)
    name = if object.respond_to?(:original_filename)
             object.original_filename
           elsif object.respond_to?(:path)
             object.path
           else
             "stream"
           end
    tempfile = Tempfile.new(["ppc-iostream", File.extname(name)])
    tempfile.binmode
    stream_to(object, tempfile)
  end

  # Copies one read-able object from one place to another in blocks, obviating the need to load
  # the whole thing into memory. Defaults to 8k blocks. Returns a File if a String is passed
  # in as the destination and returns the IO or Tempfile as passed in if one is sent as the destination.
  def stream_to(object, path_or_file, in_blocks_of = 8192)
    dstio = case path_or_file
            when String then File.new(path_or_file, "wb+")
            when IO, Tempfile then path_or_file
            end
    buffer = +""
    object.rewind
    dstio.write(buffer) while object.read(in_blocks_of, buffer)
    dstio.rewind
    dstio
  end
end