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.

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 28
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 64
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 44
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 34
def gets
  make_rewindable unless @rewindable_io
  @rewindable_io.gets
end
read(*args) click to toggle source
# File lib/rack/rewindable_input.rb, line 39
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 49
def rewind
  make_rewindable unless @rewindable_io
  @rewindable_io.rewind
end
size() click to toggle source
# File lib/rack/rewindable_input.rb, line 54
def size
  make_rewindable unless @rewindable_io
  @rewindable_io.size
end

Private Instance Methods

filesystem_has_posix_semantics?() click to toggle source
# File lib/rack/rewindable_input.rb, line 108
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 77
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