DBP file format

Please note: we're not going to describe something as painful as the pxml file here :P

file structure

a .dbp files is composed of 2 concatenated files :

1. a squashfs file
2. an *uncompressed* zip

The squashfs part contain your application(s) and everything it might need to run.

The zip part contain the meta-data related to the DBP.

meta-data structure

In the metadata zip file, you can have up to 3 directories :

1. meta: (mandatory) contain the "default.desktop" (mandatory) and all other .desktop files
2. icons: the directory where the icons will be looked after
3. teasers: the directory where the screenshots will be looked after

Beside, it is recommended to zip this without compression (using the "-Z store" flag). The reason for this is simple : the deflate algorythm wont gain much on png compressed files, and the gain on desktop files is a question of bytes. While the performance gain while reading the files is substantial for dbpd.

Sample session to build a dbp

Say you have a your application in a "rootfs" directory and a meta" directory containing the metadata.

 $ ls
 icons  meta  rootfs   teasers
 $ mksquashfs rootfs target.squash -all-root -force-gid 0
 Creating 4.0 filesystem on target.squash, block size 131072.
 ....
 $ zip -Z store -r target.zip meta icons teasers
   adding: meta/ (stored 0%)
 ...
 $ cat target.squash target.zip > target.dbp
 $ zip -A target.dbp

the desktop file(s)

This file format is normed by the free-desktop community. The complete specs can be found here, but this guide duplicates all of the bits you're likely to use.

Remember, the default.desktop file should have the Package Entry **after** the Desktop Entry

Desktop Entry

In a dbp file, only a handful of [Desktop Entry] sections should be written. It corresponds to a system menu entry targetting an application from within the dbp package. Each [Desktop Entry] section need to be a dedicated file. Here is the standard fields the dbp system reuse.

LABEL	dbpd	Repo	Description	Example
Type	R	N	Type of desktop file (Possible values: Application, Link, Directory)	Type=Application
Name	R	R	Name of the app	Name=dosbox
Comment	O	O	Description of the app	Comment=A DOS emulator
Categories	R	O	Categories, see the main ones, and the additional ones.	Categories=Game;Emulator
Exec	R	N	The binary in the squashfs part to start	Exec=dosbox
Icon	O	O	The icon in the "icons" directory (expect .png)	Icon=dosbox.png
X-DBP-Screenshot	N	O	A single screenshot for this app (as found in the "teasers" directory)	X-DBP-Screenshot=app1.png
X-DBP-Screenshots	N	O	A set of screenshots for this app (as found in the "teasers" directory)	X-DBP-Screenshots[0]=appx_0.png X-DBP-Screenshots[1]=appx_1.png
Version	N	N	Version of the app	Version=0.74+svn20200103
Terminal	N	N	Spawn a terminal for this app to run in, if set.	Terminal=false

Package Entry

This section doesnt exist in the free-desktop specification (So this is dbp exclusive stuff here). One and only one of this section should be found per dbp package. Here are the fields :

LABEL	dbpd	Repo	Description	Example
Id	R	R	Unique identifier for the dbp file.	Id=dosbox
Name	N	R	Name of the package	Name=DOSbox
Arch	O	R	Binary architecture of that package	Arch=armhf
Appdata	O	N	Name of the appdata to use (default: name of the package)	Appdata=dosbox
Icon	O	O	Icon of the package (found in the "icons" directory)	Icon=dosbox.png
Version	N	R	Version of the package	Version=0.74+svn20200103
Exec	O	N	List of executables to export With environment override	Exec=bin/dosbox;dosbox.launch
NoEnvExec	O	N	List of executables to export Without environment override
Dependency[deb]	O	O	Debian packages requiered.	Dependency[deb]=libsdl2-image-2
Dependency[dbp]	O	O	dbp package requiered to run this one.	Dependency[dbp]=dosbox

legend

letter	meaning
R	Required
O	Optionnal
N	Not used