Logsaver

A log saving tool for Android platform.

How To Integrate It Into AOSP Base

• Copy this project into AOSP code tree, like ${ANDROID_BUILD_TOP}/external/logsaver.
• Make sure you are in AOSP build environment.
  • Which means you've done envsetup and lunch.
• Add logsaver to PRODUCT_PACKAGES.
  • Mostly in device/<vendor>/<device>/XXXXX.mk
  • PRODUCT_PACKAGES += logsaver
• Cd to logsaver/security and run the setup.sh (for Android 8 SELinux).
• make
• Now the followings are what we want.
  • /system/bin/logsaver
  • /system/etc/init/logsaver.rc

SELinux Configuration for Android 8

See what we have to do in security/setup.sh.

Other Android versions are not adapted for now.

How To Use It

Example: logsaver -k /dev/kmsg /data/bootchart/klog

TODO

For Kernel Log

• Support kernel log saving.
• Support timeout quit.
  • Fixed timeout.
  • Command line timeout.
• Support max-file-size quit.
  • Fixed max-file-size.
  • Command line max-file-size.
• Support dynamic file naming.
  • Naming by index.
  • Naming by date-time.

For Android Log

• Support android log saving.

Tested Platform & Device

• Android 8.1 on Pixel 2
• Android 4.4 on Nexus 7 (2013)

The Earliest Timing To Save Logs

In brief, the timing is the same as we 'start logd' or 'load_persist_props'.

The userdata partition may be encrypted or nonencrypted. And we can not access a encrypted /data partition until it is decrypted. So search the key word 'nonencrypted' or 'vold.decrypt' in init.rc and see the following actions.

Here I just define the service logsaver in class main, which is started very soon after /data can be accessed.