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Android-specific notes
Unit tests are the first thing we want to run on Android, to get some
idea how well, if at all, the basic LO libraraies work. We want to
build even unit tests as normal Android apps, i.e. packaged as .apk
files, so that they run in a sandboxed environment like that of
whatever eventual end-user Android apps there will be that use LO
code.
Sure, we could quite easily build unit tests as plain Android
executables, push them to the device or emulator with adb and run them
from adb shell, but that would not be a good test as the environment
would be completely different. They would run as root, and not
sandboxed. We have no intent to require LibreOffice code to be used
only on "rooted" devices etc.
All Android apps are basically Java programs. They run "in" a Dalvik
virtual machine. Yes, you can also have apps where your code is only
native code, written in a compiled language like C or C++. But also
also such apps are actually started by system-provided Java
bootstrapping code (NativeActivity) running in a Dalvik VM.
Such a native app (or actually, "activity") is not built as a
executable program, but as a shared object. The Java NativeActivity
bootstrapper loads that shared object with dlopen.
It is somewhat problematic to construct .apk packages except by using
the high-level tools in the Android SDK. At least I haven't figured
out how to manually construct an .apk that is properly signed so that
it will run in the emulator. (I don't have any Android device...) I
only know how to let the SDK Ant tooling do it...
A LO Android app would work would something like this:
We have a top Java bootstrapping class
org.libreoffice.android.Bootstrap that loads a small helper native
library liblo-bootstrap.so that implements JNI wrappers for dlopen(),
dlsym(), and ELF header scanning coresponding to looking for DT_NEEDED
entries with readelf.
The Java code then loads the actual native library that corresponds to
the LibreOffice-related "program" we want to run. For unit tests, a
library that corresponds to cppunittester program. Then through helper
functions in liblo-bootstrap it calls a named function in that
"program".
This Android-specific native code (the lo-bootstrap library) is for
now in sal/android, and the Java code in the android "module"
(subdirectory right here).
--Tor Lillqvist <tml@iki.fi>
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