freecalypso-tools: doc/TIFFS-old-description annotate

annotate doc/TIFFS-old-description @ 505:7bf0d909c87e

fc-loadtool flash ID check: change of reset after the check logic This change only affects those flash configurations that have ID checks enabled. The logic for resetting the flash after the ID check has been changed as follows: 1) If the check fails, we return without attempting to reset the flash. 2) If the check is successful, we reset the flash using the configured method (could be AMD or Intel or Intel W30) instead of always doing an AMD flash reset as the original code did.

author	Mychaela Falconia <falcon@freecalypso.org>
date	Mon, 27 May 2019 19:58:01 +0000
parents	e7502631a0f9
children

rev	line source
0 e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	1 The description of TIFFS that follows was originally written in the summer of
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	2 SE52 (A.D. 2013), before the major TI source discoveries which happened later
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	3 that year. The text following the dividing line below has not been edited in
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	4 content since it was written; for a newer write-up based on the current source-
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	5 enabled understanding and reflecting the current FreeCalypso plans with respect
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	6 to this FFS, see TIFFS-Overview.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	7
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	8 -------------------------------------------------------------------------------
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	9
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	10 This is a description, based on reverse engineering, of the flash file system
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	11 (FFS) implemented in Pirelli's original firmware for the DP-L10 GSM/WiFi dual
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	12 mode mobile phone, and in the Closedmoko GTA0x modem firmware. Not knowing the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	13 "proper" name for this FFS, and needing _some_ identifier to refer to it, I
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	14 have named it Mokopir-FFS, from "Moko" and "Pirelli" - sometimes abbreviated
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	15 further to MPFFS.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	16
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	17 (I have previously called the FFS in question MysteryFFS; but now that I've
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	18 successfully reverse-engineered it, it isn't as much of a mystery any more :-)
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	19
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	20 At a high functional level, Mokopir-FFS presents the following features:
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	21
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	22 * Has a directory tree structure like UNIX file systems;
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	23
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	24 * The file system API that must be implemented inside the proprietary firmware
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	25 appears to use UNIX-style pathnames; doing strings on firmware images reveals
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	26 pathname strings like these:
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	27
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	28 /var/dbg/dar
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	29 /gsm/l3/rr_white_list
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	30 /gsm/l3/rr_medium_rxlev_thr
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	31 /gsm/l3/rr_upper_rxlev_thr
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	32 /gsm/l3/shield
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	33
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	34 Parsing the corresponding FFS image with tools included in the present
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	35 package has confirmed that the directory structure implied by these pathnames
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	36 does indeed exist in the FFS.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	37
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	38 * Absolutely no DOS-ish semantics seen anywhere: no 8.3 filenames and no
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	39 colon-separated device names (seen in the TSM30 file system source, for
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	40 example) are visible in the Closedmoko/Pirelli FFS.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	41
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	42 * File contents are stored uncompressed, but not necessarily contiguous: one
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	43 could probably store a file in FFS which is bigger than the flash sector
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	44 size, it which case it can never be contiguous in a writable FFS (see below),
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	45 and the firmware implementation seems to limit chunk sizes to a fairly small
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	46 number: on the Pirelli phones all largish files are divided into chunks of
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	47 8 KiB each, and on my GTA02 the largest observed chunk size is only 2 KiB.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	48
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	49 The smaller files, like the IMEI and the firmware ID strings in my GTA02 FFS,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	50 are contiguous.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	51
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	52 * The FFS structure is such that the length of "user" payload data stored in
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	53 each chunk (and consequently, in each file) can be known exactly in bytes,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	54 with the files/chunks able to contain arbitrary binary data. (This property
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	55 may seem obvious or trivial, as all familiar UNIX and DOS file systems have
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	56 it, but contrast with RT-11 for example.)
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	57
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	58 * The flash file system is a writable one: the running firmware can create,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	59 delete and overwrite files (and possibly directories too) in the live FFS;
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	60 thus the FFS design is such that allows these operations to be performed
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	61 within the physical constraints of NOR flash write operations.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	62
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	63 I have reverse-engineered this Mokopir-FFS on a read-only level. What it means
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	64 is that I, or anyone else who can read this document and the accompanying
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	65 source for the listing/extraction utilities, can take a Mokopir-FFS image read
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	66 out of a device and see/extract its full content: the complete directory tree
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	67 and the exact binary byte content of all files contained therein.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	68
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	69 However, the knowledge possessed by the present hacker (and conveyed in this
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	70 document and the accompanying source code) is NOT sufficient for constructing a
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	71 valid Mokopir-FFS image "in vitro" given a tree of directories and files, or
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	72 for making modifications to the file or directory content of an existing image
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	73 and producing a content-modified image that is also valid; valid as in suitable
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	74 for the original proprietary firmware to make its normal read and write
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	75 operations without noticing anything amiss.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	76
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	77 Constructing "de novo" Mokopir-FFS images or modifying existing images in such
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	78 a way that they remain 100% valid for all read and write operations of the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	79 original proprietary firmware would, at the very minimum, require an
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	80 understanding of the meaning of all fields of the on-media FFS format. Some
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	81 of these fields are still left as "non-understood" for now though: a read-only
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	82 implementation can get away with simply ignoring them, but a writer/generator
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	83 would have to put something in those fields.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	84
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	85 As you read the "read-only" description of the Mokopir-FFS on-media format in
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	86 the remainder of this document, it should become fairly obvious which pieces
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	87 are missing before our understanding of this FFS can be elevated to a
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	88 "writable" level.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	89
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	90 However, when it comes to writing new code to run on the two Calypso phones in
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	91 question (Closedmoko and Pirelli), it seems, at least to the present hacker,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	92 that a read-only understanding of Mokopir-FFS should be sufficient:
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	93
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	94 * In the case of Closedmoko GTA0x modems, the FFS is seen to contain the IMEI
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	95 and the RF calibration data. The format of the former is obvious; the latter
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	96 not so much - but in any case, the information of interest is clearly of a
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	97 read-only nature. It's difficult to tell (or rather, I haven't bothered to
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	98 experiment enough) whether the Closedmoko firmware does any writes to FFS or
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	99 if the FFS is treated as read-only outside of the production line environment,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	100 but in any case, it seems to me that for any 3rd party replacement firmware,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	101 the best strategy would be to treat the FFS as a read-only source of IMEI and
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	102 RF calibration data, and nothing more.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	103
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	104 * In the case of Pirelli phones, the FFS is used to store user data: sent and
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	105 received SMS (and MMS/email/whatever), call history, UI settings, pictures
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	106 taken with the camera, and whatever else. It also stores a ton of files
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	107 which I can only presume were meant to be immutable except at the time of
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	108 firmware updates: graphics for the UI, ringtones, i18n UI strings, and even
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	109 "helper" firmware images for the WiFi and VoIP processors. However, no IMEI
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	110 or RF calibration data are anywhere to be found in the FFS - instead this
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	111 information appears to be stored in the "factory block" at the end of the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	112 flash (in its own sector) outside of the FFS.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	113
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	114 Being able to parse FFS images extracted out of Pirelli phones "in vitro"
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	115 allows us to steal some of these helper files (UI artwork, ringtones,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	116 WiFi/VoIP helpers), and some of these might even come useful to firmware
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	117 replacement projects, but it seems to me that a replacement firmware would
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	118 be better off using its own FFS design for storing user data, and as to
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	119 retrieving the original IMEI and RF calibration data, the original FFS isn't
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	120 of any use for that anyway.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	121
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	122 =======================
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	123 Moko/Pirelli FFS format
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	124 =======================
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	125
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	126 OK, now that I'm done with the introduction, we can get to the actual
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	127 Mokopir-FFS format.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	128
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	129 * On the GTA0x modem (or at least on my GTA02; my sample size is 1) the FFS
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	130 occupies 7 flash sectors of 64 KiB each at offsets 0x380000 through 0x3E0000,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	131 inclusive.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	132
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	133 (The 4 MiB NOR flash chip used by Closedmoko has an independent R/W bank
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	134 division between the first 3 MiB and the last 1 MiB. The first 3 MiB are used
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	135 to hold the field-flashable closed firmware images distributed as *.m0 files;
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	136 the independent last megabyte holds the FFS, and thus the FW could be
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	137 implemented to do FFS writes while running from flash in the main bank.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	138 Less than half of that last megabyte appears to be used for the FFS though;
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	139 the rest appears to be unused - blank flash observed.)
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	140
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	141 * On the Pirelli the FFS occupies 18 sectors of 256 KiB each at offsets 0
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	142 through 0x440000 (inclusive) of the 2nd flash chip select, the one wired to
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	143 nCS3 on the Calypso.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	144
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	145 Each flash sector allocated to FFS begins with the following signature:
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	146
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	147 00000000: 46 66 73 23 10 02 xx yy zz FF FF FF FF FF FF FF Ffs#............
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	148
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	149 The bytes shown as xx and yy above serve a non-understood purpose; as a guess,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	150 they may hold some info for the flash wear leveling algorithm: in a "virgin"
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	151 FFS image like that found in my GTA02 (which never had a SIM card in it and
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	152 never made or received a call) or read out of a "virgin" Pirelli phone that
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	153 hasn't seen any active use yet, both of these bytes are FFs, but when I look at
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	154 FFS images read out of the Pirelli which I currently use as my everyday-use
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	155 cellphone, I see other values in sectors which must have been erased and
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	156 rewritten. A read-only implementation can ignore these bytes, as mine does.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	157
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	158 The byte shown as zz is more important though, even to a read-only
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	159 implementation. The 3 values I've encountered in this byte so far are AB, BD
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	160 and BF. Per my current understanding, in a "healthy" FFS exactly one sector
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	161 will have AB in its header, exactly one will have BF, and the rest will have
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	162 BD. The meanings are (or appear to be):
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	163
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	164 AB: the sector holds a vital data structure which I have called the active
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	165 index block;
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	166 BD: the sector holds regular data;
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	167 BF: the sector is blank except for the header, can be turned into a new AB or
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	168 BD.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	169
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	170 (Note that a flash program operation, which can turn 1s into 0s but not the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	171 other way around, can turn BF into either AB or BD - but neither AB nor BD can
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	172 be turned into any other valid value.)
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	173
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	174 In a "virgin" FFS image (as explained above) the first FFS sector is AB, the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	175 last one is BF, and the ones in between are BDs.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	176
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	177 An FFS read operation (a search for a given pathname, or a listing of all
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	178 present directories and files) needs to start with locating the active index
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	179 block - the FFS sector with AB in the header. Following this header, which is
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	180 treated as being 16 bytes long (almost everything in Mokopir-FFS is aligned on
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	181 16-byte boundaries), the active index block contains a linear array of 16-byte
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	182 records, each record describing an FFS object: directory, file or file
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	183 continuation chunk.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	184
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	185 Here is my current understanding of the 16-byte index block record structure:
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	186
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	187 2 bytes: Length of the described chunk in bytes
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	188 1 byte: Purpose/meaning not understood, ignored by my current code
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	189 1 byte: Object type
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	190 2 bytes: Descendant pointer
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	191 2 bytes: Sibling pointer
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	192 4 bytes: Data pointer
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	193 4 bytes: Purpose/meaning not understood, ignored by my current code
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	194
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	195 (On the Calypso phones of interest, all multibyte fields are in the native
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	196 little-endian byte order of the ARM7TDMI processor.)
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	197
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	198 The active index block gets filled with these records as objects are created;
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	199 the first record goes right after the 'Ffs#'...AB header (padded to 16 bytes);
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	200 the last record (at any given moment) is followed by blank flash for the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	201 remainder of the sector. Records thus appear in the order in which they are
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	202 created, which bears no direct relation to the directory tree structure.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	203
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	204 The objects, each described by a record in the index block, are organized into
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	205 a tree structure by the descendant and sibling pointers, plus the object type
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	206 indicator byte. Let's start with the latter; the following objtype byte values
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	207 have been observed:
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	208
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	209 00: deleted object - a read-only implementation should ignore everything except
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	210 the descendant and sibling pointers. (A write-capable implementation would
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	211 need more care - it would need a way of reclaiming dirty flash space taken
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	212 up by deleted/overwritten files.)
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	213
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	214 E1: a special file - see the description of the /.journal file further down
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	215 F1: a regular file (head chunk thereof)
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	216 F2: a directory
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	217 F4: file continuation chunk (explained below)
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	218
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	219 Each record in the index block has an associated chunk in one of the data
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	220 sectors; the index record contains fields giving the address and length of this
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	221 chunk. The length of a chunk is always a nonzero multiple of 16 bytes, and is
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	222 stored (as a number in bytes) in the first 16-bit field of the 16-byte index
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	223 entry. The address of each chunk is given by the data pointer field of the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	224 index record, and it is reckoned in 16-byte units (thereby 16-byte alignment is
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	225 required) from the beginning of the FFS sector group in the flash address space.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	226
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	227 For objects of type F1 and F2 (regular files and directories) the just-described
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	228 chunk begins with the name of the file or subdirectory as a NUL-terminated ASCII
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	229 string. This name is just for the current level of the directory tree, just
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	230 like in UNIX directories, thus one will have chunk names like gsm, l3, eplmn
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	231 etc, rather than /gsm/l3/eplmn. One practical effect is that one can't readily
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	232 see pathnames or any of the directory structure by looking at an FFS image as a
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	233 raw hex dump; the structure is only revealed when one uses a parsing program
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	234 like those which accompany this document.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	235
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	236 In the case of directories, the "chunk" part of the object contains only the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	237 name of the directory itself, padded with FFs to a 16-byte boundary. For
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	238 example, an FFS directory named /gsm would be represented by an object
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	239 consisting of two flash writes: a 16-byte entry in the active index block, with
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	240 the object type byte set to F2, and a corresponding 16-byte chunk in one of the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	241 data sectors, with the 16 bytes containing "gsm", a terminating NUL byte, and
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	242 12 FF bytes to pad up to 16. In the case of files, this name may be followed
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	243 by the first chunk of file data content, as explained further down.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	244
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	245 In order to parse the FFS directory tree (whether the objective is to dump the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	246 whole thing recursively or to find a specific file given a pathname), one needs
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	247 to first (well, after finding the active AB block) find the root directory node.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	248 The root directory object is similar to other directory objects: it has a type
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	249 of F2, and an associated chunk of 16 bytes in one of the data sectors. The
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	250 latter contains the name of the root node: on the Pirelli it is "/", whereas on
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	251 my GTA02 it is "/ffs-root".
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	252
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	253 The astute reader should notice that it really makes no sense to store a name
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	254 for the root node, and indeed, this name plays no part in the traversal of the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	255 directory tree given an absolute pathname. But instead this name, or rather
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	256 its first character, appears to be used for the purpose of locating the root
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	257 node itself. At first I had assumed that the index record for the root node is
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	258 always the first record in the active index block right after the signature
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	259 header - that is how it is in "virgin" FFS images, and also in some quite non-
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	260 virgin ones I have pulled from my daily-use Pirelli. Naturally my first version
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	261 of the Mokopir-FFS (then called MysteryFFS) extraction utility expected the root
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	262 node to always be at index #1. But then I got some additional Pirelli phones,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	263 and discovered that in certain cases, index record #1 is a deleted object (the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	264 original root node which has been deleted), and the new active root node is
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	265 somewhere in the middle of the index!
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	266
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	267 Thus it appears that in order to find the active root node, one needs to scan
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	268 the active index block linearly from the beginning (disregarding the tree
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	269 structure pointers in this initial pass), looking for a non-deleted object of
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	270 type F2 (a directory) whose corresponding name chunk sports a name beginning
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	271 with the '/' character. (Anyone who's been raised in UNIX will immediately
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	272 know that the path separator character '/' is the only character other than NUL
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	273 that's absolutely forbidden in the individual filenames - so this special
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	274 "root node name" is the only case of a '/' character appearing in what would
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	275 otherwise be a regular filename.)
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	276
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	277 [What causes the root node to be somewhere other than at index #1? I assume it
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	278 has to do with the dirty space reclamation / data movement algorithm. In a
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	279 "virgin" FFS image the very first sector is the active index block, and the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	280 following sector is the first to hold chunks, beginning with the name chunk of
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	281 the root node. Now what happens if all data in that sector aside from the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	282 root node name and some other mostly-static directory names becomes dirty,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	283 i.e., belonging to deleted or overwritten files? How would that flash space
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	284 get reclaimed? I assume that the FFS firmware algorithm moves all still-active
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	285 chunks to a new flash sector, invalidating the old copies - turning the latter
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	286 into deleted objects. The root node will be among them. Then at some point
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	287 the active index block is going to fill up too, and will need to be rewritten
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	288 into a new sector - at which point the previously-deleted index entries are
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	289 omitted and the root node becomes #1 again...]
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	290
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	291 Tree structure
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	292
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	293 Once the root node has been found, the descendant and sibling pointers are used
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	294 to traverse the tree structure. For each directory object, including the root
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	295 node, the descendant pointer points to the first child object of this directory:
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	296 the first file or subdirectory contained therein. (Descendant and sibling
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	297 pointers take the form of index numbers in the active index block. A "nil"
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	298 pointer is indicated by all 1s (FFFF) - the usual all-0s NULL pointer convention
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	299 couldn't be used because it's flash, where the blank state is all 1s.) If the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	300 descendant pointer of a directory object is nil, that means an empty directory.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	301 The sibling pointer of each file or directory points to its next sibling, i.e.,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	302 the next member of the same parent directory. The sibling pointer of the root
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	303 node is nil.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	304
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	305 Data content of files
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	306
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	307 Objects of type F1 are the head chunks of files. Each file has a head chunk,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	308 and may or may not have continuation chunks. More precisely, the head chunk
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	309 may contain only the name (or viewed alternatively, 0 bytes of data), or it may
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	310 contain a nonzero number of payload bytes; orthogonally to this variability,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	311 there may or may not be continuation chunk(s) present.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	312
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	313 Continuation chunks
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	314
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	315 The descendant pointer of each file head object (the object of type F1, the one
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	316 reached by traversing the directory tree) indicates whether or not there are
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	317 any continuation chunks present. If this descendant pointer is nil, there are
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	318 no continuation chunks; otherwise it points to the first continuation chunk
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	319 object. File continuation objects have type F4, don't have any siblings (the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	320 sibling pointer is nil - but see below regarding relocated chunks), and the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	321 descendant pointer of each continuation object points to the next continuation
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	322 object, if there is one - nil otherwise.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	323
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	324 Payload data delineation
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	325
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	326 Each chunk, whether head or continuation, always has a length that is a nonzero
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	327 multiple of 16 bytes. The length of the chunk here means the amount of flash
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	328 space it occupies in its data sector - which is NOT equal to the payload data
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	329 length.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	330
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	331 The head chunk of each file begins with the filename, terminated by a NUL byte.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	332 If there are any payload data bytes present in this head chunk (I'll explain
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	333 momentarily how you would tell), the byte immediately after the NUL that
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	334 terminates the filename is the first byte of the payload. In the case of a
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	335 continuation chunk, there is no filename and the first byte of the chunk is the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	336 first byte of that chunk's portion of the user data payload.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	337
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	338 Each data-containing chunk (head or continuation) has the following termination
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	339 after the last byte of that chunk's payload data: one byte of 00, followed by
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	340 however many bytes are needed ([0,15] range) of FFs to pad to a 16-byte
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	341 boundary. A file head chunk that has no payload data has the same format as a
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	342 directory name chunk: filename followed by its terminating NUL followed by
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	343 [0,15] bytes of FFs to pad to the next 16-byte boundary.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	344
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	345 When working with a head chunk, find the beginning of possible payload data (1
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	346 byte after the filename terminating NUL) and find the end per the standard
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	347 termination logic: scanning from the end of the chunk, skip FFs until 00 is
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	348 found (encountering anything else is an error). If the head chunk has no data,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	349 the effective data length (end_pointer - start_pointer) will be 0 or -1. (The
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	350 latter possibility is the most likely, as there will normally be a "shared" 00
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	351 byte, serving as both the filename terminator and the 00 before the padding
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	352 FF bytes.)
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	353
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	354 Relocated chunks
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	355
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	356 Let's go back to the scenario in which a particular data sector is full (no more
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	357 usable free space left) and contains a mixture of active and dirty (deleted or
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	358 invalidated) data. How does the dirty flash space get reclaimed, so that the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	359 amount of available space (blank flash ready to hold new data) becomes equal to
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	360 the total FFS size minus the total size of active files and overhead? It can
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	361 only be done by relocating the still-active objects from the full sector to a
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	362 new one, invalidating the old copies, and once the old sector consists of
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	363 nothing but invalidated data, subjecting it to flash erasure.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	364
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	365 So how do the active FFS objects get relocated from a "condemned" sector to a
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	366 new one? If the object is a directory, a new index entry is created, pointing
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	367 to the newly relocated name chunk, but it is then made to fit into the old tree
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	368 structure without disrupting the latter: the new index entry is added at the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	369 tail of the sibling-chain of the parent directory's descendants, the old index
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	370 entry for the same directory is invalidated (as if the directory were rmdir'ed),
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	371 and the descendant pointer of the newly written index entry is set to a copy of
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	372 the descendant pointer from the old index entry for the same directory. The
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	373 same approach is used when the head chunk of a file needs to be relocated; in
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	374 both cases a read-only FFS implementation doesn't need to do anything special to
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	375 support reading file and directory objects that have been relocated in this
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	376 manner.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	377
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	378 However, if the relocated object is a file continuation chunk, then the manner
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	379 in which such objects get relocated does affect file reading code. What if a
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	380 chunk in the middle of a chain linked by "descend" pointers needs to be moved?
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	381 What happens in this case is that the old copy of the chunk gets invalidated
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	382 (the object type byte turned to 00) like in the other object relocating cases,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	383 and the sibling pointer of that old index entry (which was originally FFFF as
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	384 continuation objects have no siblings) is set to point to the new index entry
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	385 for the same chunk. The "descend" pointer in the new index entry is a copy of
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	386 that pointer from the old index entry.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	387
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	388 The manner of chunk relocation just described has been observed in the FFS
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	389 images read out of my most recent batch of Pirelli phones - the same ones in
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	390 which the root directory object is not at index #1. Thinking about it as I
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	391 write this, I've realized that the way in which continuation objects get
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	392 relocated is exactly the same as for other object types - thus the compaction
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	393 code in the firmware doesn't need to examine what object type it is moving.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	394 However, the case of continuation chunk relocation deserves special attention
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	395 because it affects a read-only implementation like ours - the utilities whose
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	396 source accompanies this document used to fail on these FFS images until I
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	397 implemented the following additional handling:
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	398
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	399 When following the chunk chain of a file, normally the only object type that's
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	400 expected is F4 - any other object type is an error. However, as a result of
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	401 chunk relocation, one can also encounter deleted objects, i.e., type == 00.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	402 If such a deleted object is encountered, follow its sibling pointer, which must
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	403 be non-nil.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	404
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	405 Journal file
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	406
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	407 Every Mokopir-FFS image I've seen so far contains a special file named
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	408 /.journal; this file is special in the following ways:
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	409
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	410 * The object type byte is E1 instead of F1;
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	411 * Unlike regular files, this special file is internally-writable.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	412
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	413 What I mean by the above is that regular files are mostly immutable: once a
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	414 file has been created with some data content in the head chunk, it can only be
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	415 either appended to (one or more continuation chunks added), or overwritten by
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	416 creating a new file with the same name at the same level in the tree hierarchy
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	417 and invalidating the old one. But the special /.journal file is different: I
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	418 have never observed it to consist of more than the head chunk, and this head
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	419 chunk is pre-allocated with some largish and apparently fixed length (4 KiB on
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	420 my GTA02, 16 KiB on the Pirelli). This pre-allocated chunk contains what look
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	421 like 16-byte records at the beginning (on the first 4-byte boundary after the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	422 NUL terminating the ".journal" name), followed by blank flash for the remainder
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	423 of the pre-allocated chunk - so it surely looks like new flash writes happen
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	424 within this chunk.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	425
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	426 I do not currently know the purpose of this /.journal file or the meaning of the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	427 records it seems to contain. This understanding would surely be needed if one
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	428 wanted to create FFS images from scratch or to implement FFS write operations,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	429 but I reason that a read-only implementation can get away with simply ignoring
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	430 this file. I reason that this file can't be necessary in order to parse an FFS
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	431 image for reading because one needs to parse the tree structure first in order
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	432 to locate this journal file itself.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	433
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	434 -------------------------------------------------------------------------------
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	435
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	436 That's all I can think of right now. If anything is unclear, see the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	437 accompanying source code for the listing/extraction utilities: with the general
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	438 explanation given by this document, it should be clear what my code does and
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	439 why. And if a given piece of knowledge is found neither in this document nor
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	440 in my source code, then I don't know it myself either, and my read-only
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	441 Mokopir-FFS implementation makes do without it.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	442
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	443 All knowledge contained herein has been recovered by reverse engineering.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	444 Believe it or not, I have figured it out by staring at the hex dump of FFS
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	445 sectors, reasoning about how one could possibly implement an FFS given the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	446 requirement of dynamic writability and the physical constraints of flash memory,
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	447 and writing listing/extraction test code iteratively until I got something that
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	448 appears to correctly parse all FFS images available to me - the result is the
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	449 code in this package.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	450
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	451 I never got as far as attempting to locate the FFS implementation routines
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	452 within the proprietary firmware binary code images, and I haven't found an
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	453 implementation of this particular FFS in any of the leaked sources yet either.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	454 The TSM30 code doesn't seem to be of any use as its FFS appears to be totally
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	455 different. As to the more recently found LoCosto code leak, I found that one a
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	456 few days after I got the Moko/Pirelli "MysteryFFS" reverse-engineered on my
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	457 own, and when I did look at the FFS in the LoCosto code later, I saw what seems
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	458 to be a different FFS as well.
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	459
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	460 Michael Spacefalcon
e7502631a0f9 initial import from freecalypso-sw rev 1033:5ab737ac3ad7 Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	461 SE 52 Mes 16

FreeCalypso > hg > freecalypso-tools

annotate doc/TIFFS-old-description @ 505:7bf0d909c87e