Blog of spblinux

Rooting: there are some fine guides like this. The first step, unlock bootloader, resets the phone to factory: backup data first. (To see developer options on the phone: settings / about / tap 7 times on the last line / build number). In developer options: activate oem-unlock to unlock the boot loader and later usb debug mode to allow adb shell access.

• fastboot and adb shell (reference): windows installer (=minimal fastboot and adb; tested: flashing with fastboot needs cmd window with admin rights); linux: apt-get install fastboot; osx: google mfastboot-v2 download.
• twrp for moto e 2nd 4g: reference; download (version 2015-03-08)
• supersu 2.46 (2015-03-29) from chainfire.eu: download
• search for moto e 2nd logo.bin to hide the unlocked bootloader warning (fastboot flash logo logo.bin)

USB OTG: moto e 2nd 4G (xt1524) does support usb on the go (check settings / storage with attached usb storage device)

Tools (from google playstore):

• Android Terminal Emulator (even tapping works with mc, if enabled in settings, using terminal type xterm). On first start run
  su -c ” supolicy –live ‘allow untrusted_app untrusted_app_devpts chr_file setattr’ “
• sshelper ssh daemon (comes with busybox)
• Midnight Commander Installer (installation requires busybox in /system/xbin/)
  Use terminal emulator to copy busybox to system app directory /system/xbin/:
  su; mount -o remount,rw /system
  cd /data/data/com.arachnoid.sshelper/bin; cp -a * /system/xbin/
  Then edit shell script /system/xbin/mc (e.g. with mc editor)
  export TERM=xterm
  /system/xbin/mc.real $@
• juicessh ssh client
  currently needs a policy modification
  su -c ” supolicy –live ‘allow untrusted_app untrusted_app_devpts chr_file setattr’ ”
  (or permissive selinux mode) to access /dev/pts. Run in terminal emulator:
  su; setenforce 0 (and reenable with setenforce 1; getenforce shows status)
  or  with ssh:
  su -c sh -i; setenforce 1
  then logout and login again
• Root Explorer: file manager

Screencast:

• YouMap: duplicates screen to rplay software on raspberry pi
• with raspberry pi configured as wlan access point and connected to the internet by ethernet both screencast and internet access use the same wlan connection
• transmission is very stable and efficient in terms of battery life. But the first connection might have to be tried multiple times: turn on server, connect to rplay device (stop server, disconnect device, repeat from beginning). – Much better than google chromecast app and stick (phone not in list of supported devices, 2015-03).

Compiler

• C4droid with gcc and sdl plugin
• recommended to use bluetooth keyboard
• working directory is:
  /data/data/com.n0n3m4.droidc/files/
  and uses temp.c and temp as compiled binary
• storage directory is
  /storage/emulated/legacy/
• in depth tutorial for qt app
• selinux support:
  copy libselinux.so from /system/lib/ to
  /data/data/com.n0n3m4.droidc/files/gcc/arm-linux-androideabi/lib/
• download selinux header files from android.googlesource.com: platform/external/libselinux: include (e.g. android-5.1.0_r3)
• create directory selinux inside
  /data/data/com.n0n3m4.droidc/files/gcc/arm-linux-androideabi/include
• copy the header files into this directory
• In C4droid settings / G++ arguments add after -lz: -lselinux; stored in
  /data/data/com.n0n3m4.droidc/shared_prefs/com.n0n3m4.droidc_preferences.xml
• test selinux with (idea from serverfault.com)
  #include <stdio.h>
  #include <stdlib.h>
  #include <selinux/selinux.h>
  int main() {
  security_context_t con;
  if (getcon(&con) < 0) {
  perror(“Cannot getcon”);
  return 1;
  }
  printf(“%s\n”, con);
  freecon(con);
  return 0;
  }
• this program should compile and run with output:
  u:r:untrusted_app:s0
• if and only if enforcing mode of selinux is active
  su -cn u:r:system_app:s0 test
  allows to run the program test in a different security context (su is part of supersu)

Android build environment:

• tutorial on xda-developers
• personal technical notes about android by David Madore