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Packaging

Revision as of 11:17, 28 May 2012

Creating Packages for Maemo

Since Maemo is based on the Debian operating system, creating packages for Maemo borrows a lot of tools and techniques from Debian.

Further reading

The following list of resources gives in-depth information on packaging in Debian and Maemo. These links largely discuss packaging Python apps but can be used for any programming language.

• Using automake and autoconf with C++: A great beginner's tutorial on using autotools to create an easily packagable application
• Debian New Maintainers Guide: The best place for information if you have never built a .deb before
• Debian's Python Modules Team: definitive documentation for packaging Python modules for Debian
• Python Modules Policy: Reference document.
• Creating debs on Ubuntu: A great screencast and tutorial showing how to package a simple python application as a deb on Ubuntu!
• Ubuntu Packaging Guide
• Deploying and distributing software on Maemo 5: Detailed documentation on packaging for Maemo, including how to ship your software afterwards
• Forum Nokia developer documentation: General developer documentation reference
• Port an existing Debian package
• Packaging a Qt application and how it differs from the packaging described here
• User:Jebba has created a package building howto with details on every step

Checking Maemo Packages

Lintian dissects Debian packages and reports bugs and policy violations. It contains automated checks for many aspects of Debian policy as well as some checks for common errors. Unfortunately it does not check conformance to the additional Maemo policy.

Currently Maemo is creating Maemian to check its policy.

A concrete example - hello

Prerequisites

For the purposes of our article, we will be packaging a simple Hildon hello-world application. This will be a standard source tarball using autotools. For further information, you can follow this detailed tutorial on using Autotools for C++ projects.

You will need a working Maemo 5 SDK and the libhildon1-dev package, version 2.2 or greater, which can be installed in Scratchbox with the command:

fakeroot apt-get install libhildon1-dev

hello.c

The only C file in our project is hello.c:

#include <hildon/hildon.h>
 
int main(int argc, char *argv[])
{
  GtkWidget *window;
  GtkWidget *label;
 
  hildon_gtk_init(&argc, &argv);
 
  window = hildon_window_new();
  label = gtk_label_new("Hello world!");
 
  g_signal_connect(G_OBJECT (window), "destroy", G_CALLBACK (gtk_widget_destroy), NULL);
  gtk_container_add(GTK_CONTAINER(window), label);
  gtk_widget_show_all(window);
 
  gtk_main();
  return 0;
}

Autotools

The rest of the project is a small number of files to allow us to make a standard "./configure && make && make install" project with automake, aclocal and autoconf.

Using the autotools for packaging is quite simple for small projects. You need two files to define the structure of your project, Makefile.am and configure.ac.

configure.ac is a file used by automake and autoconf to generate the configure script, define the version of the resulting .tar.gz and include the tests which we need to ensure the presence of the appropriate versions of dependencies. Since hello.c is so simple, we only need to check for the standard C library and a C compiler, and for the Hildon library. The Hildon library check is done by pkg-config, which makes it easy to check the library version, and get the right compiler and linker flags. The only output file generated by the configure script will be Makefile, from the input file Makefile.in, which is in turn generated from Makefile.am

Makefile.am defines the source structure of your project, listing the files to be installed, the binaries and object files to be generated, and the relationship between the binaries and source files.

You can see that our Makefile.am is very simple, defining one source file, and one binary file. The "_SOURCES" line must start with a binary name from "bin_PROGRAMS" to make the link between the source file and the executable. The "_CPPFLAGS" and "_LDADD" lines take the Hildon preprocessor and library flags that are provided by pkg-config in configure.ac.

bin_PROGRAMS = hello
hello_SOURCES = hello.c
hello_CPPFLAGS = $(HILDON_CFLAGS)
hello_LDADD = $(HILDON_LIBS)

Once we have these files, we simply need to initialise our project, defining its license, and generating all of the required files for automake to do its thing. We do this by running:

autoreconf --force --install

The arguments to autoreconf copy required files to the project (including generic install instructions and a license).

Pay attention during the execution of autoreconf, the execution should be entirely silent if it runs correctly. If there are messages, read them and do what is required to address the issues.

Now to build your software, you have a standard configure script and can simply run

./configure
make
make install

and to build a distribution file, you have

make dist

which will create a file hello-0.1.tar.gz, which you can use for the rest of this packaging tutorial.

Packaging a .deb

The easiest way to package a .deb file is to use Debian's build helpers.

Package your application as you would distribute it in a .tar.gz (when using autotools, this is done with "make distcheck"). In our example, we uncompress hello-0.1.tar.gz, and change the current directory to hello-0.1.

$ tar xfz hello-0.1.tar.gz
$ cd hello-0.1

Then we run dh_make, which initialises the Debian package management file structure (among other things):

$ dh_make -e <my email address> -f ../hello-0.1.tar.gz -c GPL

You can of course choose a different licence for your package.

Answer the resulting questions - in this case, we are packaging a single binary.

We can now edit the files in the debian/ directory which has been created to their desired values, before packaging the software. In fact, we can delete many of these files. All of the files ending in “.ex” or “.EX” are example files, intended to help you package different types of software.

If you use a standard configure script, you do not need to modify any files except debian/control, where the Hildon build-time dependency should be added. Change the Build-Depends line to read (by adding "libhildon1" at the end):

Build-Depends: debhelper (>= 5), autotools-dev, libhildon1 (>= 2.2)

Before creating a .deb, you should set a changelog entry. .deb changelogs follow a special format, so rather than editing the files by hand, use the dch helper application. This will allow you to add what new features went into this application, give credit, and so on. It is an especially important file because it sets the version and revision of the source and binary packages. On saving, a syntax check is performed which ensures that the resulting file is OK. The file format is completely documented in the Debian packaging guide.

Finally, we generate a .deb from the source code using the command:

dpkg-buildpackage -sa -rfakeroot -k<my email address>

You should now have several files created in the parent directory to where you unpacked the source code. I have;

hello_0.1.orig.tar.gz
hello_0.1-1_i386.deb
hello_0.1-1.diff.gz
hello_0.1-1.dsc
hello_0.1-1_i386.changes

Now change the target architecture to ARMEL and rebuild it, to generate hello_0.1-1_arm.deb:

sb-conf se FREMANTLE_ARMEL
dpkg-buildpackage -sa -rfakeroot -k<my email address>

Additional information

Ignoring git metadata

If you use git then you may not want to include the entire git repo in your source bundle. With dpkg-source version 1.13.25 the -i option is not git-aware so you can do:

 dpkg-buildpackage -rfakeroot -sa  -i -I.git

Adding build-time dependencies

If your program uses another library, such as Hildon in the above example, then both the Debian package and the configure script must depend on the library. Otherwise, since the autobuilder only installs packages explicitly required to build your package, the build will fail.

Often, the Debian package has a different name to the pkg-config file, just like in the Hildon example. One way to check which package owns a pkg-config file is to use dpkg-query on the pkg-config file, for example the mafw pkg-config file (notice the extra .pc file extension):

dpkg-query --search mafw.pc

which looks through the installed packages and finds:

libmafw0-dev: /usr/lib/pkgconfig/mafw.pc

Then you know that you must add libmafw0-dev to the Build-Depends line in debian/control if you use the mafw pkg-config file in configure.ac.

Checking build-time dependencies

You may verify that your Build-Depends field in debian/control is complete by running:

dpkg-depcheck -m dpkg-buildpackage -rfakeroot -b

in the source tree. (You will need to fakeroot apt-get install devscripts for this to work).

Adding an icon and desktop file

To ensure that your package shows up in the application menu, you will need to install an icon and a .desktop file with your package.

The icon can be in a number of formats. To keep things simple, you can use this 48x48 .png as your icon for now.

The format of .desktop files is specified by the freedesktop.org desktop entry spec, with a number of Maemo specific extensions. The simplest possible .desktop file for Maemo contains a "Desktop Entry" group containing an indicator that it refers to an application, the application name, the icon to use, and a path to the executable which will launch the application. Other standard keys can be found in the spec.

[Desktop Entry]
Type=Application
Name=Hello!
Icon=hello
Exec=/usr/bin/hello

Pixmaps referenced without an absolute path in the desktop file can be installed in a number of locations, specified in the freedesktop.org icon theme spec. The simplest place to put the icon is in /usr/share/icons. The Icon entry above will thus match /usr/share/icons/hello.png.

Once you have created these files in your source directory, you will need to add the following to Makefile.am to ensure that they are distributed in the tarball (created during make dist) installed in the right place, and packaged correctly, and you should re-run autoreconf, configure, make dist and dpkg_buildpackage once you have done so.

icondir = $(datadir)/icons
dist_icon_DATA = hello.png
 
desktopdir = $(datadir)/applications/hildon
dist_desktop_DATA = hello.desktop

To make the package installable using Hildon Application Manager (which will get launched when you select the package), you should follow the #Maemo-specific packaging information below. In particular, you must set the "Section" to one of the valid sections below in the "debian/control" file.

Testing your package

The first place you can test your app is in Scratchbox. Start Xephyr and the Maemo GUI as described in the Maemo 5 SDK instructions, then run your application by hand from within Scratchbox.

Once you have created .deb packages of your application for x86 and armel, you can also test the installation process and test your application on your N900.

dpkg -i hello_0.1-1_i386.deb

/home/<username>/MyDocs

To test on your device, copy the armel .deb file to the .documents directory on your device, and install it by selecting it in the file manager. You will need to ensure that the OS version on your device is compatible with the development environment in your Scratchbox.

Once the package is installed, you will be able to launch it directly from the command line in the X terminal application. To get the application to appear in the application list, you will need to include an icon and desktop file in the package as described in the packaging policy.

Uploading to extras-devel

Maemo-specific packaging information

Packaging policy

Maemo packages follow the Debian Policy, but there are some items where Maemo is more strict, since it is an embedded distribution, and other areas where it is more relaxed, since it supports only one user at a time on a single target device and UI framework. In other areas, the policy differs from Debian because we have different objectives and maintainers, and because we have provided different infrastructure for packaging and distributing software.

Most of the specifics for Maemo packaging are outlined in the Maemo packaging guidelines.

Sections

For applications to be installable throughh Hildon Application Manager, the "Secton:" field in the debian/control file must conform to certain naming conventions.

The conformant section names are outlined in the packaging guidelines, and are listed below.

If the package's section starts "user/", but is not any of the above, the Application Manager forces them into an "Other" section.

Desktop files

Desktop files are used to launch applications from the main application menu. Their format is standardised and documented in the freedesktop.org desktop file spec. The Maemo application menu uses the same desktop files, but looks for them to a slightly different location; /usr/share/applications/hildon instead of /usr/share/applications.

The location of the directory in which to install .desktop files can also be obtained using pkg-config:

pkg-config --variable=desktopentrydir osso-af-settings

The returned value can be used in a Makefile to install the desktop file to the correct location.

There is some official documentation on desktop files for Maemo applications.

Maemo-specific fields

There are a number of Maemo-specific Debian packaging fields that are handled by Application manager. The Application manager documentation outlines them.

Displaying an icon in the Application Manager next to your package

Displaying an icon in the Application Manager next to your package makes it look pretty and makes your package stand out, and it is not that hard to do.

1. Make an image that is 48×48 pixels. The image can be saved in any format that is supported by GdkPixbufLoader on Maemo, but PNG is commonly used.
2. base64 encode the image. This can be done in many ways, depending on the platform, but assuming you are in Scratchbox:

   fakeroot apt-get update
   fakeroot apt-get install sharutils
   uuencode -m <name of 48×48 image> <name of 48×48 image> > <name of 48×48 image>.base64
   

3. Add the field XB-Maemo-Icon-26 to your debian/control (in Maemo4 the size of the icons was 26×26 pixels, hence the name of the field, which has not changed in Maemo 5)
4. Open the base64 version of your image and copy from the line under begin-base64 644 <name of 48×48 image> to the line above the ===
5. Add this to the XB-Maemo-Icon-26 field
6. Add a space in front of every line of the encoded icon. You can do that automatically using sed when you base64 encode the image:

   uuencode -m <name of 48×48 image> <name of 48×48 image> | sed -e s,^,\ ,  > <name of 48×48 image>.base64
   

Here is an example of a properly formatted Maemo-Icon-26: (of wrong image size)

Description: Chess...
XB-Maemo-Icon-26: 
 iVBORw0KGgoAAAANSUhEUgAAABoAAAAaCAYAAACpSkzOAAAABGdBTUEAAK/INwWK6QAAABl0
 RVh0U29mdHdhcmUAQWRvYmUgSW1hZ2VSZWFkeXHJZTwAAALxSURBVHja3FZNTBNREP669J/S
 XYxtKRWl1JOSFBIPhkitCQeNiaKBmzdj9Ggk0ZOBxHDWixcTjV6MF+WiIB40YEyMBMGYEqQK
 tLS2lG7pdre0pF3WtxslgJRuD2J0kpfdTN7O976Z782sRpIk7IZR2C2TGW1cv8xaY5WuXLy8
 iW5XV5fk8/kkr9e7ya/T6SSNRiOViikvbbmDDD590SusZBGYDiDwJbDud7vdvYIgIJfLYXV1
 tSwhrQrSfRX6/26N/j+gkjW6ce06HE4HGEctGuj9oEwUzFYz5ubmEA6HQVEUisUi8vn8b4rd
 zjRbNxCZrr+3t7XTzjrnvMfdxMi7xj6OIRaPIbWcQjabVdRWKBTkrX4SZ2SjvCtKXf+tkxxD
 M5MetwfHj/lwwueHy+WCVqvdehdHKq7R6JvbpfNMAGiGhs1mg9ls3sS+4hodbDqCwef9mA9P
 7vhhVVWV3BGUOomiaCSufEWMxNwimlweMFYbpoMfyp70J6t8xanLZgWs8Ak07N0Hau0P3qOs
 wIHnl5FJx2E1WlUFuXrzIS713KusRplMCoLAgl2O4N34ODQ4VRaot6cbUzMRNNQ/w/uJWXWM
 eH5JARkYHsLQMIe1NZEpB7Sn1uKFhkL3maO4cL5NHVAo+hkPnrzEq2HqQIf/3ICzvr7FXmeH
 3qBXlslkgtFoVBS3YfbcKRRFfJpagE6vUwd0//FbjI7mkcvnGoNfg51ORx3sNju+hWYxMxsk
 jHlF2jJgdXU1DAaDrDx/kQAVRREJlldXo8kJoPlQ8wHSevosFgs5MmE5H0IingDP8eAzPAQC
 tkJakDz05Hsks+poPzwg6+Luo9chVb2O3Hilv7V6W5nO02cVX3wxjsj3CMKRBUSjUcQWY0iy
 SQVoi6XJaiQxubKpI02yj2xk6BoaBr0BqXRKCZpYSiCZlIXCguM4pWtvY0ypyUtt87PSIj/t
 pJ/JICzLKiBLySTYVArpdFrp3DuMhRZVqfvnJ+wPAQYA1hdr5EDqltYAAAAASUVORK5CYII=

Please note that if you are packaging a command-line only program that can be executed by the user, you should use the CLI icon only.

Bugtracker location

As a requirement[1] Is strongly recommended for your package being promoted from Extras-testing to Extras, your debian/control file must have a link to a bugtracker, which is visible in the maemo.org packages interface. It is possible to request a component at bugs.maemo.org or use a Garage project bugtracker, or even, for simple packages, an email address .

Add the field ‘XSBC-Bugtracker’ to your debian/control, for example:

XSBC-Bugtracker: https://bugs.maemo.org/enter_bug.cgi?product=mypackage

Alternatively for e-mail addresses, you can use the following format:

XSBC-Bugtracker: mailto:yourname@example.com

Pretty names

A package can specify a pretty name for itself. This name is displayed in the Application manager UI instead of the real package name.

The pretty name is specified with the 'XSBC-Maemo-Display-Name' field in your debian/control file, for example:

XSBC-Maemo-Display-Name: Hello, world!

Maemo revision string

If an upstream package is re-packaged or modified for Maemo, the Maemo revision string should be appended to the upstream revision, in the debian/changelog file. So if in Debian the package name was something like "Myapp-0.4-2" in maemo this package will be called "Myapp-0.4-2maemo0". The number after the "maemo" string is a progressive number.

Maemo upgrade description

Tell users what changed in the update:

XB-Maemo-Upgrade-Description: Formatted like "Description". 
 Will be displayed if user upgrades to new version and clicks
 on "Details".
 .
 Human-readable and translatable.

As with all Maemo-specific fields, the "XB-" prefix is needed so the field will remain in the binary package.

Translations of text fields

The following fields can be translated to the end user's local language: Maemo-Display-Name, Description and Maemo-Upgrade-Description. It is strongly recommended to make use of this possibility so that end users understand what the application does for them while browsing through the Application Manager.

The translation is done by adding a suffix like "-de_DE" to the respective field name, where "de_DE" is the locale the translated text is for. For example, if LC_MESSAGES equals de_DE, the Application Manager first tries "Description-de_DE" to find the description of a package and then falls back to "Description".

Here's an example:

Description: Chess...
XB-Maemo-Display-Name: My package name
XB-Maemo-Upgrade-Description: Formatted like "Description". 
XB-Description-de_DE: Schach...
XB-Maemo-Display-Name-de_DE: Mein Packetname
XB-Maemo-Upgrade-Description-de_DE: Formatiert wie "Description". 

Note how "Description" becomes "XB-Description-xx_YY" when a locale suffix is added. This is because it's not a standard Debian field any longer.

Debhelper 7

Since the Autobuilder's use of the Squeeze devkit, debhelper 7 is supported natively by it.

Follow the steps on that link to also make your FREMANTLE_* target use the Squeeze devkit.

Note: dh_make doesn't seem to be provided by the Squeeze devkit, so you'll have to run it outside of Scratchbox to get a debian/ folder based on debhelper 7.

A backport of Debhelper 7 for Fremantle is available in extras-devel.

$ fakeroot apt-get install debhelper7 

It works transparently and can coexist with debhelper 5 in the SDK. It even works on the autobuilder, if the package specifies the correct build-dependency of debhelper7. The following lines in debian/rules are necessary to use the new debhelper:

PATH:=/usr/bin/dh7:/usr/bin:$(PATH)
export PATH
SBOX_REDIRECT_IGNORE=/usr/bin/perl
export SBOX_REDIRECT_IGNORE

In debian/control change:

Build-Depends: debhelper (>= 7) [...]

to

Build-Depends: debhelper7 (>= 7) [...]

Further information about the updated debhelper is available at User:Tanner#debhelper7.

If you also need a more recent CDBS, then use the package cdbs-dh7, which conflicts with the standard CDBS and does not work on autobuilder yet.

Alternatively, you can try to use debhelper 5. Debian packages that require level 7 need some changes, for example:

• debian/compat: 7 -> 5
• debian/control: Build-Depends: debhelper (>= 7) -> debhelper (>= 5)
• Possibly, comment out a few dh_* calls from debian/rules, which might not exist on level 5

Things might get complex if the packaging already uses some new features of level 7, like CDBS-style helper rules. In such cases, looking at versions of packages written prior to the compatibility level upgrade might help doing the downgrade (and most Debian packages are kept in public SCMs like svn.debian.org).

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