Linux on the mobile is the way forward

May 26, 2010 / 0 comments

I decided last night to upgrade the firmware on my G1. I've been fairly happy with my lightly hacked Android 1.6 (basically the stock T-Mobile image rooted and with a couple of apps added) but I'm interested in whether Froyo will bring performance improvements and the office is now full of Desire users so I figured I'd install 2.1 to see if it was any good, and prepare for 2.2. I went for CyanogenMod as it seems to be fairly sane ROM put together by someone with some clue.

Of course I decided to ignore some of the instructions; particularly the bit about doing a factory reset first. Most of my data is easily backed up, either to Google or locally, but I wanted to keep my SMS+MMS history. There's nothing really that interesting there, and the SMS stuff is backed up automatically via SMS Backup, but still. It was a challenge. What I ended up finding was that if I didn't do the data deletion then Contacts wouldn't work, but I'd keep the SMS/MMS. And if I did the data deletion everything worked fine but I didn't have the SMS/MMS history.

I fired up adb to have a look around the filesystem, to see if there was something obvious. And there was! I found /data/data/com.android.providers.telephony/databases/mmssms.db, which is actually an SQLite database of received messages. So I booted up with the old data present, logged in, tarred up all of /data, copied it across to my desktop, reset the phone and deleted all data, waited for it to boot, extracted mmssms.db from the tarball and put it back on the phone. Result! My message threads reappeared. Turns out that wasn't enough for MMS, but that was solved by copying the contents of /data/data/com.android.providers.telephony/app_parts/ across as well.

Yes, I accept this is kludgey and most end users aren't going to do it, but a couple of points:

  • I'm flashing an unsupported ROM. I expect things to potentially break and not be able to complain to anyone about it. I'm very happy that it's an option, having had issues in the past where an operator wouldn't release an updated Nokia ROM for months after its release even when it fixed major issues.
  • This is something I wouldn't have been able to do under WinMo or Symbian. I've had a world of pain in the past moving between phones, even when using Nokia's PC Suite to try and copy stuff from the old one to the new one. Being able to get a full shell on the phone is hugely useful for dealing with this stuff when it goes wrong or you want to do something slightly different.

While the above is Android specific I'm fairly sure WebOS on the Pre or Maemo on the N900 would offer me the same level of power and control. I think I've just convinced myself that alternative smartphone OSes are no longer viable options.

Random election related numbers

May 13, 2010 / 0 comments

We appear to have a government again, which is always helpful. Let's see how they do. While all the deliberation was going on Dad and I had a ponder about exactly what your chances of voting for a winner were. The Guardian helpfully have the results dataset available, so I nabbed that. They may have updated it since I did; it certainly seemed to be a bit off compared with the BBC. Anyway.

29,577,337 - total votes cast.
13,982,219 - total votes cast for winning MPs.
7,279,220 - total votes cast for winning MPs in the new government (ie Conservative or LibDem).

So there was a 47.27% chance of a vote being for a winning MP, but only 24.61% chance that a vote was not only for a winning MP but also one that ended up being part of the coalition.

Another interesting number; 220 seats were won with 50% or more of the vote, 540 with more than 40%. That's higher than I expected.

Going to DebConf10

May 11, 2010 / 0 comments

im_going_to_debconf10.png

Not that I ever thought I wasn't going, but due to some uncertainty about where I needed flights from I've only got round to booking things today - wish I'd gone ahead and done it last week!

Outbound:

2010-07-31 10:55 BHD -> 12:15 LHR BD85
2010-07-31 16:20 LHR -> 19:00 EWR VS001

Inbound:

2010-08-08 18:15 JFK -> 06:35 LHR VS004
2010-08-09 10:55 LHR -> 12:20 BHD BD84

See you all there!

Out, damn'd PGP v3

Apr 23, 2010 / 0 comments

Nearly a year ago people starting worrying about the complexity of SHA-1 being reduced and the potential availability of viable attacks against things such as PGP keys that used SHA-1. Many people (myself included) generated a new key, or updated preferences on keys that were otherwise strong enough. There were worries about what this might mean for Debian. We were getting ahead of ourselves a bit though. Firstly there haven't been any public viable attacks that I'm aware of (though of course this doesn't mean we shouldn't continue to migrate away), but secondly there's a much easier method of attack. PGP v3 keys. To quote RFC4880:

V3 keys are deprecated. They contain three weaknesses. First, it is relatively easy to construct a V3 key that has the same Key ID as any other key because the Key ID is simply the low 64 bits of the public modulus. Secondly, because the fingerprint of a V3 key hashes the key material, but not its length, there is an increased opportunity for fingerprint collisions. Third, there are weaknesses in the MD5 hash algorithm that make developers prefer other algorithms. See below for a fuller discussion of Key IDs and fingerprints.

At the time of writing Debian has 21 remaining v3 keys. This is a significant improvement over a year ago, when we had 200, but it's still 21 more than I'd like. I've been chasing people since last May (starting with those who had v3 + v4 keys, all of whom now only have a v4 key) and we're down to the stragglers. So it's time to name and shame, in the hope of kicking them into action. The following keys are what's left (doesn't match the currently active keyring because we've had a few replacements since the last promote):

0x0D2156BD3D97C149 Michael Stone <mstone>
0x225FD911CD269B31 Carlos Barros <cbf>
0x31E73F14E298966D James R. Van Zandt <jrv>
0x366CD3FEEBC11B01 Chris Waters <xtifr>
0x37A73FE355E8BC4D Frederic Lepied <lepied>
0x3E973117DCC528E9 Ardo van Rangelrooij <ardo>
0x5C7A46637953F711 Rich Sahlender <rsahlen>
0x5D6560F85F30F005 Craig Brozefsky <craig>
0x6B0E322836129171 Jim Westveer <jwest>
0x723724B4A5B6DD31 Christian Meder <meder>
0x7629B22ED71DAABD Adrian Bridgett <bridgett>
0x8FFC405EFD5A67CD Adam Di Carlo <aph>
0xB0D269DE17F3D4D1 Matthew Vernon <matthew>
0xBC151FC8D2A913A1 Peter S Galbraith <psg>
0xC1A0A171C2DCD3B1 Jim Mintha <jmintha>
0xC3168EBA23F5ADDB Ian Jackson <iwj>
0xCE951B1160D74C7D Patrick Cole <ltd>
0xE82A8B0D57137FE5 Paul Seelig <pseelig>
0xF20E242CE77AC835 Brian White <bcwhite>
0xFBAA570C3087194D Alan Bain <afrb2>
0xFFD1B4AC7C19FD19 David Engel <david>

Of these keys only 2 voted in the recent DPL election. 8 have failed to make any response to my mails (3 since last August). Only 9 have uploaded a package since August 2008. And 10 were already known to the MIA database. Some of them have stated they'll sort out a new key, but not yet done so.

If you are one of these people, please either get a new key sorted and signed and reply to the mails I've sent you, or reply and say you no longer wish to be involved in Debian. And if you know any of these people, encourage them to get a new key sorted and offer to sign it for them.

Fizz buzz

Mar 8, 2010 / 0 comments

Inspired by a conversation about interview coding tasks from a list I'm on, I present the following - I considered it too long to email there. It took me longer than I expected to write; my x86 assembly is quite rusty. I'm not claiming it's pretty, but it fits in a single sector and most of the overhead is actually ELF structures.

; nasm -f elf fizzbuzz.asm
; ld -melf_i386 -s -o fizzbuzz fizzbuzz.o
; ./fizzbuzz

section .data

fizz	db	" fizz"
fizzlen	equ	$ - fizz
buzz	db	" buzz"
buzzlen	equ	$ - buzz
num	db	"   "
numend	equ	$ - 1
numlen	equ	$ - num
nl	db	0xa
nllen	equ	$ - nl

curnum	db 1

section .text

	global _start

_start:
	mov ax, [curnum]
	call printnum

	mov ax, [curnum]
	mov cx, 3
	xor dx, dx
	div cx
	cmp dx, 0
	jnz notfizz

	mov edx, fizzlen
	mov ecx, fizz
	call printstr

notfizz:
	mov ax, [curnum]
	mov cx, 5
	xor dx, dx
	div cx
	cmp dx, 0
	jnz notbuzz

	mov edx, buzzlen
	mov ecx, buzz
	call printstr

notbuzz:
	mov edx, nllen
	mov ecx, nl
	call printstr

	inc BYTE [curnum]
	cmp BYTE [curnum], 100
	jle _start

	xor ebx, ebx
	mov eax, 1
	int 0x80

printnum:
	mov edi, numend
	mov cx, 10
p1:
	xor edx, edx
	div cx
	add dx, '0'
	mov [edi], dl
	dec edi
	cmp ax, 0
	jne p1

	mov ecx, num
	mov edx, numlen
printstr:
	mov ebx, 1
	mov eax, 4
	int 0x80
	ret

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