"sys-filewrap" is responsible for
 wrapping a filesystem object with a
 file-like mechanism.

It simply provides two functions:
 ensureMode(mode): Ensures that a
  mode is valid, and translates it.
 create(dev, file, mode):
  Open a file using a given proxy,
  filename and mode.

The mode you give to it can be one of
 the following:
 false: Read "rb"
 true: Write "wb"
 "append": Append "ab"
           May have some readability
            propertiues - just in
            case, I've added 'read',
            but don't get your hopes
            up...

It returns two things - a table, that
 being the file object, and the
 'close' function from that object,
 for closing the file without using
 a potentially modifiable table.

If the table is nil, then the "close"
 function is actually a string, that
 being the error.

The possible functions are:
 [arw] close(): Closes the file.
 [arw] seek(whence, pos): Seeks in
  the file.
 [aw] write(data): Writes to the
  file.
 [arw] read(data): Reads from the
  file.

NOTE: Some of these may not actually
 work. They're just there as more or
 less a "do no harm" approach.

-- This is released into
 the public domain.
-- No warranty is provided,
 implied or otherwise.