From: Daniel Martin <martin@...>
Date: 2006-07-25T00:56:44+09:00
Subject: Re: How can I parse binary files?

Fabio Vitale <fabio@sferaconsulting.it> writes:

> This time I'm trying to write a binary file.
>
> Q1: why does the structure MRKMessageFlags does not get the apropriate 
> values?

I'm not sure.  It appears to be a bug in bit-struct.  Here's a
workaround; in your code replace the bit that sets the flag bits with:

  # work around bit-struct nested types bug
  flags = msg.flags
  flags.flagSeen      = 1
  flags.flagFlagged   = 1
  msg.flags = flags

> Q2: how do I convert a date to seconds-since-1970?

Don't assign date a string, assign it a Time object.  The easiest way
to get one of those is with Time.parse:

  msg.date = Time.parse("Mon Jul 24 12:34:04 2006")

Your file loop now looks like this: (I also added calls to write out
the data to the file)

File.open("imap2.mrk", "wb") {|f|
#<MRKHeader version=1, uid_Validity=1106138982,
#           uid_next=5887, last_write_counter=9962, 
# unused="\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\r\n">

  mrk_header = MRKHeader.new()
  mrk_header.version = 1
  mrk_header.uid_Validity = 1106138982
  mrk_header.uid_next = 5887
  mrk_header.last_write_counter = 9962
  # I omitted modifying unused since in theory we don't need to
  # change the last two bytes to "\r\n" - it is unused, after all
  puts mrk_header.inspect
  f.write(mrk_header)

  msg = MRKMessage.new()
  msg.filename = "md50000006021.msg"

  # work around bit-struct nested types bug
  flags = msg.flags
  flags.flagSeen      = 1
  flags.flagFlagged   = 1
  msg.flags = flags

  msg.uid = 5885
  msg.msg_size = 4184
  msg.date = Time.parse("Mon Jul 24 12:34:04 2006")

  puts msg.inspect
  f.write(msg)
}