[tips] [Howto] Support Nvidia Optimus on Ubuntu 12.04 LTS (precise) [No Bumblebee needed]

For laptops which use muxless Nvidia Optimus, there's a new way to support officially on Ubuntu 12.04 LTS.

 #sudo apt-get install nvidia-319-updates nvidia-prime xserver-xorg-lts-raring 

The command will upgrade
 * kernel to 3.8 ,
 * X server RandR to 1.4
 * Install Nvidia driver version 319.

After reboot, it will use nvidia driver by default.
There is no need to upgrade to 13.10 if you prefer 12.04 LTS.

[tips] g_clear_pointer

因為在tracking一個bug, 
所以要backport indicator-power這個package到ubuntu precise.
意外發現了glib在2.33之後支援的一個還滿好用的function: 
g_clear_pointer()

簡言之以前的寫法,要把物件刪除再把指標設為NULL:

if (priv->object_path != NULL) {
    g_free(priv->object_path);
    priv->object_path = NULL;
}

現在只要一行就可以達成了

g_clear_pointer (&priv->object_path, g_free);

當然要backport的話作法就是相反~~

[tips] rewrite debian/ubuntu 's lighttpd conf script from perl to python

Today I want to port lighttpd on another platform which basically a debian sarge system but without perl and dpkg package system on it. Since it's a debian based platform so I start from porting debian's binary lighttpd package, however I've found there're some perl script lays in /usr/share/lighttpd which are used when lighttpd startup.

While I can easily dump the result of perl script into a textfile,
and then startup my lighttpd correctly, I thought "maybe port it to python is not a bad idea." (since my target platform has python!), so here is the effort:
create-mime.assign.py

#!/usr/bin/python
#
# This script directly translate from debian's lighttpd perl script:
# create-mime.assign.pl
#
# Author: timchen119.at.nospam.gmail.com
# License: Public Domain
#
import sys

try:
 f = open("/etc/mime.types",'r')
 extensions = {}
 print "mimetype.assign = ("
 for line in f:
     line = line.strip()
     if line.startswith('#'): continue
     if line != "":
         splitlist = line.split()
         if len(splitlist) < 2: continue
         mime = splitlist[0]
         for ext in splitlist[1:]:
             if ext in extensions.keys(): continue
             extensions[ext] = 1
             print '".%s" => "%s",' % (ext,mime)
 f.close()
 print ")"
except Exception,e:
 print e
 sys.exit(1)

include-conf-enabled.py

#!/usr/bin/python
#
# This script directly translate from debian's lighttpd perl script:
# include-conf-enabled.pl
#
# Author: timchen119.at.nospam.gmail.com
# License: Public Domain
#

import os,glob

confdir = "/etc/lighttpd/"
enabled = "conf-enabled/*.conf"

os.chdir(confdir)

for file in sorted(glob.glob(enabled)):
 print 'include "%s"' % file

use-ipv6.py

#!/usr/bin/python
#
# This script directly translate from ubuntu's lighttpd perl script:
# use-ipv6.pl
#
# Author: timchen119.at.nospam.gmail.com
# License: Public Domain
#

import socket

##this sometimes not accurate. (like in vserver mode)
#if socket.has_ipv6:
#

try:
 if socket.socket(socket.AF_INET6,socket.SOCK_STREAM,0):
     print 'server.use-ipv6 = "enable"'
except:
 pass

All of these files can be found in http://kalug.linux.org.tw/~tim/lighttpd-debian-python-script/
Well something quite interesting happened when I port the debian's create-mime.assign.pl into python, It's that my python script's final result is not equivalent to perl one and has more mime types than its :

--- perlmime.txt    2008-07-14 15:29:23.000000000 +0800
+++ pymime.txt    2008-07-14 15:29:33.000000000 +0800
@@ -114,6 +114,11 @@
".dvi" => "application/x-dvi",
".rhtml" => "application/x-httpd-eruby",
".flac" => "application/x-flac",
+".pfa" => "application/x-font",
+".pfb" => "application/x-font",
+".gsf" => "application/x-font",
+".pcf" => "application/x-font",
+".pcf.Z" => "application/x-font",
".mm" => "application/x-freemind",
".gnumeric" => "application/x-gnumeric",
".sgf" => "application/x-go-sgf",
@@ -193,6 +198,11 @@
".pk" => "application/x-tex-pk",
".texinfo" => "application/x-texinfo",
".texi" => "application/x-texinfo",
+".~" => "application/x-trash",
+".%" => "application/x-trash",
+".bak" => "application/x-trash",
+".old" => "application/x-trash",
+".sik" => "application/x-trash",
".t" => "application/x-troff",
".tr" => "application/x-troff",
".roff" => "application/x-troff",
@@ -282,6 +292,7 @@
".tgf" => "chemical/x-mdl-tgf",
".mcif" => "chemical/x-mmcif",
".mol2" => "chemical/x-mol2",
+".b" => "chemical/x-molconn-Z",
".gpt" => "chemical/x-mopac-graph",
".mop" => "chemical/x-mopac-input",
".mopcrt" => "chemical/x-mopac-input",

So I start to dig why this happened, and I've found a strange perl regex filter all these mimetypes out, I believe it's a minor bug in original perl program. (or it does implicitly doing something meaningful? well I can't figure it out.)

--- create-mime.assign.pl    2008-07-14 15:35:58.000000000 +0800
+++ create-mime.assign.pl.new    2008-07-14 15:36:07.000000000 +0800
@@ -7,7 +7,7 @@
chomp;
s/\#.*//;
next if /^\w*$/;
-  if(/^([a-z0-9\/+-.]+)\s+((?:[a-z0-9.+-]+[ ]?)+)$/) {
+  if(/^([A-Za-z0-9\/+-.~%]+)\s+((?:[A-Za-z0-9.+-~%]+[ ]?)+)$/) {
  foreach(split / /, $2) {
    # mime.types can have same extension for different
    # mime types

replace this line and this will produce same results as mine.

usage:
just copy these py scripts to /usr/share/lighttpd
and change these lines if you're using debian based system

#### external configuration files
## mimetype mapping
#include_shell "/usr/share/lighttpd/create-mime.assign.pl"
include_shell "/usr/share/lighttpd/create-mime.assign.py"

## load enabled configuration files,
## read /etc/lighttpd/conf-available/README first
#include_shell "/usr/share/lighttpd/include-conf-enabled.pl"
include_shell "/usr/share/lighttpd/include-conf-enabled.py"