Getting Root Privileges in the Android Emulator

Preface

During Android development, programs often inevitably need to operate on content under system directories. Although Android's kernel is a Linux system, the way to switch to root in Linux is sudo root, but Android does not provide us with an su file. So we need to add the su file to the system that needs root, and also change the permissions of the su binary.

Operation Steps

Step 1

Start the emulator that needs to be rooted

Step 2

In the directory that contains the supersu.apk file, execute the following command

$ adb -e install supersu.apk Install super.apk onto the emulator. After it is installed, do not rush to run this App

Step 3

$ emulator.exe -avd [模拟器名字] -writable-system Run the emulator in a writable manner. You should use this command in the tools directory under your sdk directory, because that is where the emulator.exe program is.

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Step 4

Unzip the downloaded supersu.zip file. You can see that many of the folders inside contain su files. My emulator is Androidx86, so I found the su.pie file under the x86 folder. If your Android version is 5.1 or a system greater than version 5.1, using su.pie is more suitable than the su file and can avoid some unnecessary problems. Next you need to do the following

$ adb root

$ adb remount

$ adb -e push C:\SuperSU-v2.79\x86\su.pie /system/xbin/su

In the root state, adb remount means remounting the system partition to make the system partition writable again. Under normal circumstances, files under system are not allowed to be written to; they are read-only. Copy su.pie to the /system/xbin/su file by means of push

Note: if your Android emulator's system version is less than 5.1, you need to use the su binary, not su.pie

$ adb -e push C:\SuperSU-v2.79\x86\su /system/xbin/su

Step 5

Now we need to use adb to modify the permissions of the su binary in the emulator

$ adb -e shell

$ su root

$ cd /system/xbin

$ chmod 06755 su

If you find that through ls -l you see that your su file's permissions are rwsr_x_x, that means it has succeeded

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Step 6

Now we need to install the su binary (I am not sure exactly where it is installed; maybe it is installed into supersu.apk? I don't know either) and set it as a background daemon

$ su --install $ su --daemon&

I have not carefully looked into the purpose of this step for now

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Step 7

Set SELinux restrictions, mainly disabling SELinux. The specific place to execute this command is not particularly fixed, but it seems there is no problem executing it at the end

$ setenforce 0

At this point, my Android emulator seems to have completed rooting. Reopen the Android emulator, tap to run the supersu program (that is, the program just installed onto your Android system). After opening, it may prompt you to update; you can ignore it and use it directly. Then your system has been rooted, and you can perform some operations that involve the system.

Note

If when you finally tap the supersu App it prompts that the su file cannot be found, that means your su file may not match, or it is because you opened the supersu App before completing the su file setup. Haha, you can try uninstalling the supersu App and starting over from the beginning with the steps above.