According to this comment in #1880:
https://github.com/topjohnwu/Magisk/issues/1880#issuecomment-546657588
If Linux recycled our PPID, and coincidentally the process that reused
the PPID is root, AND init wants to kill the whole process group,
magiskd will get killed as a result.
There is no real way to block a SIGKILL signal, so we simply make sure
our daemon PID is the process group leader by renaming the directory.
Close#1880
On API 23+, the platform unifies the way to handle drawable
resources across processes: all drawables can be passed via Icon.
This allows us to send raw bitmap to the system without the need to
specify a resource ID. This means that we are allowed to NOT include
these drawable resources within our stub APK, since our full APK can
draw the images programmatically and send raw bitmaps to the system.
The plural form of the words 'documentation' and 'following' are used very rarely if ever and I don't believe that they should be used in this particular context.
For some reason, Google Play Protect randomly blocks our self-signed
repackaged Magisk Manager APKs. Since we are root, the sky is our
limit, so yeah, disable package verification temporarily when installing
patched APKs, LOLz
Close#1979
Usually, the communication between native and the app is done via
sending intents to either broadcast or activity. These communication
channels are for launching root requests dialogs, sending root request
notifications (the toast you see when an app gained root access), and
root request logging.
Sending intents by am (activity manager) usually requires specifying
the component name in the format of <pkg>/<class name>. This means parts
of Magisk Manager cannot be randomized or else the native daemon is
unable to know where to send data to the app.
On modern Android (not sure which API is it introduced), it is possible
to send broadcasts to a package, not a specific component. Which
component will receive the intent depends on the intent filter declared
in AndroidManifest.xml. Since we already have a mechanism in native code
to keep track of the package name of Magisk Manager, this makes it
perfect to pass intents to Magisk Manager that have components being
randomly obfuscated (stub APKs).
There are a few caveats though. Although this broadcasting method works
perfectly fine on AOSP and most systems, there are OEMs out there
shipping ROMs blocking broadcasts unexpectedly. In order to make sure
Magisk works in all kinds of scenarios, we run actual tests every boot
to determine which communication method should be used.
We have 3 methods in total, ordered in preference:
1. Broadcasting to a package
2. Broadcasting to a specific component
3. Starting a specific activity component
Method 3 will always work on any device, but the downside is anytime
a communication happens, Magisk Manager will steal foreground focus
regardless of whether UI is drawn. Method 1 is the only way to support
obfuscated stub APKs. The communication test will test method 1 and 2,
and if Magisk Manager is able to receive the messages, it will then
update the daemon configuration to use whichever is preferable. If none
of the broadcasts can be delivered, then the fallback method 3 will be
used.
