class Rack::RewindableInput

RewindableInput uses, though it does not close the original IO object.
Don’t forget to call #close when you’re done. This frees up temporary resources that
this by buffering the data into a tempfile, which is rewindable.
Class which can make any IO object rewindable, including non-rewindable ones. It does

def close

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

has created.
wrapped IO object. Cleans up any temporary resources that this RewindableInput
Closes this RewindableInput object without closing the originally 
def close
  if @rewindable_io
    if @unlinked
      @rewindable_io.close
    else
      @rewindable_io.close!
    end
    @rewindable_io = nil
  end
end

def each(&block) 

def each(&block)
  make_rewindable unless @rewindable_io
  @rewindable_io.each(&block)
end

def filesystem_has_posix_semantics? 

def filesystem_has_posix_semantics?
  RUBY_PLATFORM !~ /(mswin|mingw|cygwin|java)/
end

def gets 

def gets
  make_rewindable unless @rewindable_io
  @rewindable_io.gets
end

def initialize(io) 

def initialize(io)
  @io = io
  @rewindable_io = nil
  @unlinked = false
end

def make_rewindable 

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)
  @rewindable_io.binmode
  # :nocov:
  if filesystem_has_posix_semantics?
    raise 'Unlink failed. IO closed.' if @rewindable_io.closed?
    @unlinked = true
  end
  # :nocov:
  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

def read(*args) 

def read(*args)
  make_rewindable unless @rewindable_io
  @rewindable_io.read(*args)
end

def rewind 

def rewind
  make_rewindable unless @rewindable_io
  @rewindable_io.rewind
end

def size 

def size
  make_rewindable unless @rewindable_io
  @rewindable_io.size
end