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{ Monthly Archives } January 2009

Programmer art, it’s deadly!

So one of the other things I worked on at Linux.conf.au was a project Joel Stanley started, “Open Velociraptor Per Child, the Game!”.

The game comes out of the Open Velociraptor Per Child project’s ideas. The OVPC project aims to give every child in the world their very own Velociraptor. The game simulates what would happen if this project was ever to achieve it’s wonderful but lofty goal.

My main contribution was adding support for (very bad) collision detection, scoring and difficult levels. However, what I spent most of my time was spent making bad programmer art, that of the particularly gruesome child death animation. I like to think it was this artwork that meant we won top spot at the Gaming Miniconf competition, beating the “Shave Bdale” game.

You can download the game from the git repository. Have fun!

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2009 01 28 mithro Gaming Miniconf Comments (0)

Compiling for Windows using Cygwin on Linux….

So for the past week while I have been at the best conference in the world I have been trying to compile tpserver-cpp for Windows. I had done the hard work and gotten it to compile (as documented here, here and here) on Windows previously. However, as I was in Hobart at a Linux conference I didn’t really have access to Windows computer. That was not going to stop me, so I attempted to cross compile the binaries under Linux. This has a number of advantages as it would mean when someone finally gets around to creating a autobuilder, we can produce Windows binaries too.

Ubuntu provides the mingw32 compilers in the repository so I didn’t think it would be all that hard to get working. The problem is that tpserver-cpp does not have a “native” Windows support but cygwin comes to the rescue and provides a compatibly layer. Using cygwin turned out to not be as simple as using mingw32 compiler with the cygwin headers.

I ended up using crosstool to build my own cygwin compiler. I battled for a long while with the fact that Ubuntu now enables “fortify source” by default. This breaks many versions of things like binutils and gcc (which often do naughty things which fortify source does not like). After I figured out how to disable it, I was still was only able to get an ancient version of gcc to compile (3.3.6) which meant I had to fix a lot of problems in the tpserver-cpp code. I guess someone had to do it eventually, but it was annoying that I was forced too.

I then manually downloaded a bunch of cygwin packages to build a tree for the dependencies (such as boost and guile). This was much faster then trying to compile them on my own. Finally, I was able to build tperver-cpp and create a Windows binary! I can confirm it runs fine under Wine and am now getting friends who are still shacked to Windows to test it there.

It sounds much simpler now, but it took me over a week of work to boil it down to these steps. It was like a constant game of wack-a-mole, once I had solved one problem another popped up.

So what now in this area? I want to get a recent version of the compiler working and preferably build all the dependencies ourselves (rather then rely on the cygwin compiled versions). I would ultimately like to see the cygwin compilers being packaged with Ubuntu/Debian in the same way that the mingw32 compilers are. I don’t know if any of that is likely to happen however as I never seem to have enought time. For now I have uploaded a copy of my cross compiler (It needs to be extracted so it is found in /opt/crosstool).

I hope this helps someone!

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2009 01 27 mithro linux.conf.au
Thousand Parsec Comments (1)

OSDC & orbital death, better late then never…

So last year at the end of November I spoke at OSDC. I had been meaning to blog about the conference but never gotten around to doing so. The conference was great, but like previous OSDC’s I came down with something. Sadly, this meant that missed Andrew Tridgell’s talk about the EU-Microsoft agreement. Joel, who had been camped out in my lounge room for the week, said it was really worth listening too. I really wish OSDC recorded all the talks like Linux.conf.au does.

As part of speaking at the conference I had to produce a paper. This paper puts into writing a lot of what I have been talking about. I wasn’t going to post it, but after getting a email out of the blue about the topic, I’ve decided to put a copy here on my blog. I might as well also upload the presentation I gave, but it won’t be very interesting by itself. Both are released under a CC-BY-SA.

If there is one thing that any budding game developer (open source or otherwise) should take away from this talk, it is the following:

When a person is looking for normal software, they have an issue to solve.
When looking for computer games, they are looking to be entertained.

This fundamental difference in mindset should drive every aspect of your game, website and release process.

Edit: How could I forget? A big thanks goes out to Leslie Hawthorn who helped proof read the paper and making it much easier to read!

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2009 01 26 mithro Games Comments (0)

Reading cookies from most Firefox versions…

Yesterday, I wrote about how to reading the cookies from Firefox 3.0 from Python. This code snippet extends the previous example by adding code which finds the cookie file on various different operating systems (Windows, Linux and Mac OS X). Hope this helps people who need to do this.

#! /usr/bin/env python
# Reading the cookie's from Firefox/Mozilla. Supports Firefox 3.0 and Firefox 2.x
#
# Author: Noah Fontes <nfontes AT cynigram DOT com>, 
#         Tim Ansell <mithro AT mithis DOT com>
# License: MIT
 
def sqlite2cookie(filename):
    from cStringIO import StringIO
    from pysqlite2 import dbapi2 as sqlite
 
    con = sqlite.connect(filename)
 
    cur = con.cursor()
    cur.execute("select host, path, isSecure, expiry, name, value from moz_cookies")
 
    ftstr = ["FALSE","TRUE"]
 
    s = StringIO()
    s.write("""\
# Netscape HTTP Cookie File
# http://www.netscape.com/newsref/std/cookie_spec.html
# This is a generated file!  Do not edit.
""")
    for item in cur.fetchall():
        s.write("%s\t%s\t%s\t%s\t%s\t%s\t%s\n" % (
            item[0], ftstr[item[0].startswith('.')], item[1],
            ftstr[item[2]], item[3], item[4], item[5]))
 
    s.seek(0)
 
    cookie_jar = cookielib.MozillaCookieJar()
    cookie_jar._really_load(s, '', True, True)
    return cookie_jar
 
import cookielib
import os
import sys
import logging
import ConfigParser
 
# Set up cookie jar paths
def _get_firefox_cookie_jar (path):
    profiles_ini = os.path.join(path, 'profiles.ini')
    if not os.path.exists(path) or not os.path.exists(profiles_ini):
        return None
 
    # Open profiles.ini and read the path for the first profile
    profiles_ini_reader = ConfigParser.ConfigParser();
    profiles_ini_reader.readfp(open(profiles_ini))
    profile_name = profiles_ini_reader.get('Profile0', 'Path', True)
 
    profile_path = os.path.join(path, profile_name)
    if not os.path.exists(profile_path):
        return None
    else:
        if os.path.join(profile_path, 'cookies.sqlite'):
            return os.path.join(profile_path, 'cookies.sqlite')
        elif os.path.join(profile_path, 'cookies.txt'):
            return os.path.join(profile_path, 'cookies.txt')
 
def _get_firefox_nt_cookie_jar ():
    # See http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/473846
    try:
        import _winreg
        import win32api
    except ImportError:
        logging.error('Cannot load winreg -- running windows and win32api loaded?')
    key = _winreg.OpenKey(_winreg.HKEY_CURRENT_USER, r'Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders')
    try:
        result = _winreg.QueryValueEx(key, 'AppData')
    except WindowsError:
        return None
    else:
        key.Close()
        if ret[1] == _winreg.REG_EXPAND_SZ:
            result = win32api.ExpandEnvironmentStrings(ret[0])
        else:
            result = ret[0]
 
    return _get_firefox_cookie_jar(os.path.join(result, r'Mozilla\Firefox\Profiles'))
 
def _get_firefox_posix_cookie_jar ():
    return _get_firefox_cookie_jar(os.path.expanduser(r'~/.mozilla/firefox'))
 
def _get_firefox_mac_cookie_jar ():
    # First of all...
    result = _get_firefox_cookie_jar(os.path.expanduser(r'~/Library/Mozilla/Firefox/Profiles'))
    if result == None:
        result = _get_firefox_cookie_jar(os.path.expanduser(r'~/Library/Application Support/Firefox/Profiles'))
    return result
 
FIREFOX_COOKIE_JARS = {
    'nt': _get_firefox_nt_cookie_jar,
    'posix': _get_firefox_posix_cookie_jar,
    'mac': _get_firefox_mac_cookie_jar
}
 
cookie_jar = None
try:
    cookie_jar = FIREFOX_COOKIE_JARS[os.name]()
except KeyError:
    cookie_jar = None
 
path = raw_input('Path to cookie jar file [%s]: ' % cookie_jar)
if path.strip():
    # Some input specified, set it
    cookie_jar = os.path.realpath(os.path.expanduser(path.strip()))
 
if cookie_jar.endswith('.sqlite'):
    cookie_jar = sqlite2cookie(cookie_jar)
else:
    cookie_jar = cookielib.MozillaCookieJar(cookie_jar)

Edit: The latest version of this code can be found at http://blog.mithis.com/cgi-bin/gitweb.cgi and includes numerous fixes and updates.

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2009 01 20 mithro Python Comments (8)

WTF power scripts went in Intrepid….

On previous versions of Ubuntu, the scripts which are called after a resume from suspend have been found in /etc/acpi/resume.d directory. I used this functionality to turn off some of the hardware in my Vaio which I don’t use (such as the bluetooth and the cdrom drive).

This stopped working when I upgraded to Ubuntu Intrepid. Even more strangely while the scripts are still installed, even they are never called.

It appears that thanks to moving towards HAL (which is probably a “Good Thing”) these scripts are no longer used. The scripts which are used can be found in /etc/pm/. Not only has the location changed, but the script format has too.

Previously, my script was found in /etc/acpi/resume.d/99-custom.sh looked like the following,

#! /bin/sh
# Turn off the CD drive and the bluetooth device
echo 1 > /sys/devices/platform/sony-laptop/cdpower
echo 0 > /sys/devices/platform/sony-laptop/cdpower
 
echo 1 > /sys/devices/platform/sony-laptop/bluetoothpower
echo 0 > /sys/devices/platform/sony-laptop/bluetoothpower

Now my script script must be found in /etc/pm/sleep.d/10-custom and looks like the following,

#!/bin/sh -e
case "$1" in
	resume)
		# Turn off the CD drive and the bluetooth device
		echo 1 > /sys/devices/platform/sony-laptop/cdpower
		echo 0 > /sys/devices/platform/sony-laptop/cdpower
 
		echo 1 > /sys/devices/platform/sony-laptop/bluetoothpower
		echo 0 > /sys/devices/platform/sony-laptop/bluetoothpower
	;;
esac

The main reason I’m posting this on my blog is that this change does not seem to be documented anywhere. Searching on Google for things like “resume script intrepid” or “/etc/acpi/resume.d intrepid” does not come up with anything useful. Hopefully some people will find this helpful.

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2009 01 19 mithro Uncategorized Comments (3)

$#%#! UTF-8 in Python

This is not a post about using UTF-8 properly in Python, but doing evil, evil things.

Python dutifully respects the $LANG environment variable on the terminal. It turns out that a lot of the time this variable is totally wrong, it’s set to something like C even though the terminal is UTF-8 encoding.

The problem is that there is no easy way to change a file’s encoding after it’s open, well until this horrible hack! The following code will force the output encoding of stdout to UTF-8 even if started with LANG=C.

# License: MIT
try:
    print u"\u263A"
except Exception, e:
    print e
 
import sys
print sys.stdout.encoding
 
from ctypes import pythonapi, py_object, c_char_p
PyFile_SetEncoding = pythonapi.PyFile_SetEncoding
PyFile_SetEncoding.argtypes = (py_object, c_char_p)
if not PyFile_SetEncoding(sys.stdout, "UTF-8"):
    raise ValueError
 
try:
    print u"\u263A"
except Exception, e:
    print e
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2009 01 19 mithro Python Comments (0)

Reading Firefox 3.x cookies in Python

I found the following code snippet on my hard drive today. It allows you to access Firefox 3.x cookies in Python. Firefox 3.x moved away from the older text file format to a sqlite database.

This code is useful if you want to access something behind an authentication gateway and you also access the page through your web browser. You can also use this code to convert a sqlite database into a cookie file CURL can read.

I didn’t write this code, it was written by Noah Fontes when we where doing some scraping of the Google Summer of Code website (before I joined Google).

#! /usr/bin/env python
# Protocol implementation for handling gsocmentors.com transactions
# Author: Noah Fontes nfontes AT cynigram DOT com
# License: MIT
 
def sqlite2cookie(filename):
    from cStringIO import StringIO
    from pysqlite2 import dbapi2 as sqlite
 
    con = sqlite.connect(filename)
 
    cur = con.cursor()
    cur.execute("select host, path, isSecure, expiry, name, value from moz_cookies")
 
    ftstr = ["FALSE","TRUE"]
 
    s = StringIO()
    s.write("""\
# Netscape HTTP Cookie File
# http://www.netscape.com/newsref/std/cookie_spec.html
# This is a generated file!  Do not edit.
""")
    for item in cur.fetchall():
        s.write("%s\t%s\t%s\t%s\t%s\t%s\t%s\n" % (
            item[0], ftstr[item[0].startswith('.')], item[1],
            ftstr[item[2]], item[3], item[4], item[5]))
 
    s.seek(0)
 
    cookie_jar = cookielib.MozillaCookieJar()
    cookie_jar._really_load(s, '', True, True)
    return cookie_jar
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2009 01 19 mithro Python Comments (5)