class Rack::RewindableInput

Class which can make any IO object rewindable, including non-rewindable ones. It does this by buffering the data into a tempfile, which is rewindable.

rack.input is required to be rewindable, so if your input stream IO is non-rewindable by nature (e.g. a pipe or a socket) then you can wrap it in an object of this class to easily make it rewindable.

Don't forget to call close when you're done. This frees up temporary resources that RewindableInput uses, though it does not close the original IO object.

Public Class Methods

new(io) click to toggle source 
# File lib/rack/rewindable_input.rb, line 16
def initialize(io)
  @io = io
  @rewindable_io = nil
  @unlinked = false
end

Public Instance Methods

close() click to toggle source

Closes this RewindableInput object without closing the originally wrapped IO object. Cleans up any temporary resources that this RewindableInput has created.

This method may be called multiple times. It does nothing on subsequent calls.

# File lib/rack/rewindable_input.rb, line 47
def close
  if @rewindable_io
    if @unlinked
      @rewindable_io.close
    else
      @rewindable_io.close!
    end
    @rewindable_io = nil
  end
end
each(&block) click to toggle source 
# File lib/rack/rewindable_input.rb, line 32
def each(&block)
  make_rewindable unless @rewindable_io
  @rewindable_io.each(&block)
end
gets() click to toggle source 
# File lib/rack/rewindable_input.rb, line 22
def gets
  make_rewindable unless @rewindable_io
  @rewindable_io.gets
end
read(*args) click to toggle source 
# File lib/rack/rewindable_input.rb, line 27
def read(*args)
  make_rewindable unless @rewindable_io
  @rewindable_io.read(*args)
end
rewind() click to toggle source 
# File lib/rack/rewindable_input.rb, line 37
def rewind
  make_rewindable unless @rewindable_io
  @rewindable_io.rewind
end

Private Instance Methods

filesystem_has_posix_semantics?() click to toggle source 
# File lib/rack/rewindable_input.rb, line 89
def filesystem_has_posix_semantics?
  RUBY_PLATFORM !~ /(mswin|mingw|cygwin|java)/
end
make_rewindable() click to toggle source 
# File lib/rack/rewindable_input.rb, line 60
def make_rewindable
  # Buffer all data into a tempfile. Since this tempfile is private to this
  # RewindableInput object, we chmod it so that nobody else can read or write
  # it. On POSIX filesystems we also unlink the file so that it doesn't
  # even have a file entry on the filesystem anymore, though we can still
  # access it because we have the file handle open.
  @rewindable_io = Tempfile.new('RackRewindableInput')
  @rewindable_io.chmod(0000)
  @rewindable_io.set_encoding(Encoding::BINARY) if @rewindable_io.respond_to?(:set_encoding)
  @rewindable_io.binmode
  if filesystem_has_posix_semantics?
    raise 'Unlink failed. IO closed.' if @rewindable_io.closed?
    @unlinked = true
  end

  buffer = "".dup
  while @io.read(1024 * 4, buffer)
    entire_buffer_written_out = false
    while !entire_buffer_written_out
      written = @rewindable_io.write(buffer)
      entire_buffer_written_out = written == buffer.bytesize
      if !entire_buffer_written_out
        buffer.slice!(0 .. written - 1)
      end
    end
  end
  @rewindable_io.rewind
end