narcdec - Nokia .Arc Decoder / Decompressor 
-------------------------------------------

Some code path ideas and data on the format of .Arc
files ruthlessly copied from NbuExplorer 
(sourceforge.net/projects/nbuexplorer) code.

narcdec is licensed under GPLv3 (as is NbuExplorer).

This is a little fastly coded tool because I didnt
want to install a windows OS (or use anything .NET related)
to decode the Backup.Arc file from my Nokia 6630.

Note: only tested with a file from a Nokia 6630, but I 
guess it could work with ones from other Symbian S60 2nd Ed
era (or so) phones. I purposely didnt implement formats
I didnt have a decode example for, so I'll accept patches
if you can test them.

NOTE: Currently it doesnt (for my example file) understand
the 10-byte header (TODO), and there is a 6-byte footer
saying "RM-104" (???).

Current analysis on the header:
00 xx xx 00 00 ?? ?? ?? 00 03
xx xx = number of files in archive (little endian 16-bit)
?? = changes, no idea what this is (chksum or date?) 
others = constant (still no idea)

And for you who wont bother to read the source;
the files are encoded like this (effectively in an array):
name	length	explanation
---------------------------
len	1	length of unicode (UTF-16) filename in bytes
fn	len	filename (eg. C:\Nokia\Images\wtf.jpg but UTF-16)
meta	10	unknown metadata (you can have this hexdumped)
luncmp	4	uint32_t uncompressed length
lcmp	4	uint32_t compressed length
cdata	lcmp	zlib stream compressed file content

Note: Even 0 length files are "compressed" to 8 bytes... 
we dont bother to "uncompress" that data ;p

--
Urja Rannikko <urjaman@gmail.com>