Class: IO

Inherits:
Object show all
Defined in:
lib/puppet/util/monkey_patches.rb

Class Method Summary collapse

Class Method Details

.binwrite(name, string, offset = nil) ⇒ Object 



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# File 'lib/puppet/util/monkey_patches.rb', line 42

def self.binwrite(name, string, offset = nil)
  # Determine if we should truncate or not.  Since the truncate method on a
  # file handle isn't implemented on all platforms, safer to do this in what
  # looks like the libc / POSIX flag - which is usually pretty robust.
  # --daniel 2012-03-11
  mode = Fcntl::O_CREAT | Fcntl::O_WRONLY | (offset.nil? ? Fcntl::O_TRUNC : 0)

  # We have to duplicate the mode because Ruby on Windows is a bit precious,
  # and doesn't actually carry over the mode.  It won't work to just use
  # open, either, because that doesn't like our system modes and the default
  # open bits don't do what we need, which is awesome. --daniel 2012-03-30
  IO.open(IO::sysopen(name, mode), mode) do |f|
    # ...seek to our desired offset, then write the bytes.  Don't try to
    # seek past the start of the file, eh, because who knows what platform
    # would legitimately blow up if we did that.
    #
    # Double-check the positioning, too, since destroying data isn't my idea
    # of a good time. --daniel 2012-03-11
    target = [0, offset.to_i].max
    unless (landed = f.sysseek(target, IO::SEEK_SET)) == target
      raise "unable to seek to target offset #{target} in #{name}: got to #{landed}"
    end

    f.syswrite(string)
  end
end