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Archive for the ‘programming’ Category

Cross compiling samba-3.6.1 for ARM

04 Jan

After some googling I figured out how to compile samba for ARM, the device I am compiling samba for is “chumby one” ( look at http://wiki.chumby.com to get the compiler toolchain for it )

Here are the steps:

1. Download the sources, obviously.
2. export these env vars on your build machine:

export LD_LIBRARY_PATH=/usr/arm-linux/lib
export LDFLAGS=-L/usr/arm-linux/lib
export CPPFLAGS=-I/usr/arm-linux/include
export CC=arm-linux-gcc

3. edit your configure file, look for this:

if test x"$libreplace_cv_HAVE_GETADDRINFO" = x"yes"; then
# getaddrinfo is broken on some AIX systems
# see bug 5910, use our replacements if we detect
# a broken system.
if test "$cross_compiling" = yes; then :

change it to:

if test x"$libreplace_cv_HAVE_GETADDRINFO" = x"yes"; then
# getaddrinfo is broken on some AIX systems
# see bug 5910, use our replacements if we detect
# a broken system.
if test "$cross_compiling" = no; then :

why this? more info here: https://bugzilla.samba.org/show_bug.cgi?id=8410
I made a guess and it works for me.

4. invoke the configure script like so:

./configure --host=i686 --target=arm-linux samba_cv_CC_NEGATIVE_ENUM_VALUES=yes ac_cv_file__proc_sys_kernel_core_pattern=yes --prefix=/mnt/usb/samba

5. edit the makefile, change this:

CPPFLAGS=-DHAVE_CONFIG_H -I/usr/arm-linux/include -Iinclude -I./include -I. -I. -I./../lib/replace -I./../lib/tevent -I./librpc -I./.. -I./../lib/popt -I/usr/local/include

to this:

CPPFLAGS=-DHAVE_CONFIG_H -I/usr/arm-linux/include -Iinclude -I./include -I. -I. -I./../lib/replace -I./../lib/tevent -I./librpc -I./.. -I./../lib/popt

I am not a linux guru so I dont understand why it is including /usr/local/include when I am cross compiling, Samba project needs to fix these small issues, specially for ARM, with ARM gaining foothold in the server market.

6. run make

make

7. Copy files to chumby
I didnt do “make install”, obviously. i copied the bins in the /samba-3.6.1/source3/bin in the samba source folder on build machine to /mnt/usb/samba on chumby


scp * root@CHUMBY-IP:/mnt/usb/samba/

8. update the LD_LIBRARY_PATH on your arm device, chumy in this case.

export LD_LIBRARY_PATH=/mnt/usb/samba:$LD_LIBRARY_PATH

9. Test *

ssh root@CHUMBY-IP
cd /mnt/usb/samba
./smbget

10. make some required folders in /mnt/usb/samba

mkdir private
mkdir var
mkdir var/locks

11. run smbd and give it the conf file

./smbd -i --configfile=/mnt/usb/samba/samba.conf -S

12. tip: use -d 10 for more incase of errors

./smbd -i --configfile=/mnt/usb/samba/samba.conf -S -d 10

13. you can put the samba.conf in /mnt/usb/samba/lib

mv /mnt/usb/samba/samba.conf /mnt/usb/samba/lib/

14. sample samba.conf file:

[global]
workgroup = WORKGROUP
netbios name = CHUMBY

[ready]
path = /mnt/usb/samba_share
guest ok = yes
read only = no

[torrents]
path = /mnt/usb/torrents_share
guest ok = yes
read only = no

15. add samba user, we will use root since chumby comes with this only and there is no useradd command on the device.


smbpasswd -L -a root
smbpasswd -L -e root

16. test on other computers, enter root as user and password you set as the password.

Good luck, you are going to need it.

* works for me ….

 
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Posted in Chumby, programming

 

Windows Phone app development and the significance of DSLs.

27 Jul

Computers were supposed to do all the work for all humans, but as programmers we often neglect that very basic purpose of these machines. So we go on writing code doing every little bit ourselves, sure there are libraries to do some of that but using libraries does not really solve the problem. Good design for software is important, but we should not be designing and thinking how to write code when we want to download a file from network, when we need to parse an XML file, or any other easy but mundane task.

I have always thought about domain specific languages as a way to not only boost productivity but also free our thoughts from these small menial and mundane tasks. I am so excited about domain specific languages that I have thought numerous times to continue some research studies in this area. Sadly I havent been able to find any good place yet in Helsinki.

QML or QtQuick is an excellent DSL for creating nicely animated user interfaces, not just for desktop computers but also for mobile devices. The productivity boost is immense, I wrote complete applications in Qt Quick in weeks which even iPhone developers took months to write. Still more wild that the Qt Quick app ran fine on N900, N8 and other Nokia Qt devices. Since that time I have been hooked on Qt Quick. I havent found a better DSL for UI’s than Qt Quick. It is so simple, no crazy xml syntax like in XAML. XAML might be more powerful but the power is lost in its complexity and IMO bad idea of using XML.

The second experience of DSL came with LINQ when I wrote my first app for Windows Phone. I had previously done similar app on Android, iPhone and Qt/Symbian where I needed to parse huge XML documents, so I had to spend weeks just to write the code to handle the SAX events and create a state machine. This code was fragile and just too much work. Thank god for json.

Coming back to the point, the experience of parsing XML with LINQ was quite the opposite, it was … pleasant and enjoyable. I was amused by the speed at which I wrote the code and how simple it was. It all made sense.

I think Microsoft is on the right path. They already have two DSL’s incorporated in Windows Phone development, writing apps therefore for WP is quite easy and fun experience.

I hope in the future DSL’s will become even more common and we will have write apps in DSLs which are then glued together by a general purpose language.

 
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Posted in creative, nokia, programming, Qt

 

Improving Qt’s properties.

01 Jul

I have known Qt for about 9 years now. My first encounter with Qt was as a normal user who was exploring Linux to find out what the fuss was all about. With KDE I got my first experience of Qt. But I have only very recently started to use Qt as a development tool, and I have been very happy about that. Makes life easy, with Qt being ported to Symbian, Meego the gates are open for developers to make money. Since I like to experiment with all the platforms no matter who they are from, I also played around with Objective-C on iPhone some while ago.

While Qt offers many many nice features which make Objective-C look like from stone age. Objective-C has some nice features as well, one I mentioned in my previous post, which Qt already solves rather nicely and in a better way as one of the commenter pointed out. Objective-C and Qt are quite similar in a sense that they provide improvements on top of an already existing language. Qt with meta object compiler and Obj-C with something similar.

So back to the point, I now use Q_PROPERTY macro in my QObjects based classes a lot:

class Person : public QObject
{
Q_OBJECT
Q_PROPERTY(QString name READ name WRITE setName)

public:
void setName(const QString& aName) { iName = aName; }
QString name() const { return iName; }

private:
QString iName;
};

Now consider this Objective-C code:

// person.h
@interface Person : NSObject
{
NSString* name;
}
@property (nonatomic, retain) NSString* name; // same as Q_OBJECT 

// person.m:
@implementation Person
@synthesize name; // this generates getter/setter in the .m file

// rest of the code ...

So do you see what I see ? In the Objective-C version of the code I don't have to write the getter and setter methods, whereas in Qt i have to. I think all the information to automatically implement the getter and setter functions is already in the Q_PROPERTY macro, may be the moc compiler can go ahead and also generate the getter and setter methods for us ?

 
1 Comment

Posted in nokia, objective c, programming, Qt

 

Developing Maemo5 and MeeGo applications on Windows

21 May

Maemo/Meego devices are like a computer that you can put in your pocket, for example the N900. Before N900 these maemo devices had been slow, but thanks to the iphone the whole computer industry has realized the importance of speed. N900 is not slow, what i like about this phone is the keyboard and the great web browser that it has. Just imagine the scenario, you are reading a web page on your desktop and then when you have to catch the bus, that page opens up when you start the browser on your N900. This is possible with the firefox addon called the Mozilla Weave. N900 is just awesome, it just needs to exercise 4 hours a week to lose some extra fat that it has, but other wise I really like it.

But perhaps the best thing about N900 is that my Qt apps that I write for  Symbian  also work with little modifications on my N900! you dont even need to install some crazy toolchains or use the linux os to do any of this; with the Nokia Qt SDK you can do all of this from your windows computer. Even though its in beta right now; but every thing works; i am using it for a meego/maemo app i am doing and no issues yet

 
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Posted in nokia, programming, Qt

 

Compiling Qt4.6 with OpenSSL Support on Windows with MingW

01 Dec

The Symbian port of Qt is a blessing, no more head banging. Work will be so much easier. The best thing about using Qt for Symbian development is that you dont need to use Carbide or the Emulator, you can use QtCreator to do most of your work. So I downloaded the 4.6 and before I can use it to continue my QFacebookConnect library, I need to compile it with OpenSSL support enabled. You have to do a lot of googling/binging to get that information. Well here is how you do it:

in the command prompt:
SET LIB=c:\openssl\lib\mingw;%LIB%
SET INCLUDE=c:\openssl\include;%INCLUDE%
SET PATH=c:\openssl;%PATH%

now go to the Qt source folder and execute the configure.exe like so:

configure.exe -openssl

and finally
mingw32-make

and here a nice demo of qt4.6 while it compiles for you.

 
1 Comment

Posted in nokia, programming, Qt

 

c++ std::string

10 Jul

the c++ string or more specifically std::string is a great improvement over the c-strings which are null terminated. c++ strings use a length fields to keep track of how long the string is as compared to c-string which use the NULL ‘\0′ character to keep track of where the string ends.

The c-strings have been around for so long and are used in so many places that when people start to use the std::string they get confused. For example today i wanted to use std::string to hold binary data, i knew that this was possible but i couldn’t figure out how. Then stack overflow came to the rescue. This question is explained very well there.

Thanks Stack Overflow :)

 
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Posted in c, programming