Run native executable in Android App

Demo †

Here's demo application called "Run Native Exe" to:

run local UNIX commands
run native executable downloaded from the Web

Package: NativeExe-0.2.apk
Source code: on Github (ADT project)

To install the package,

Go to Settings→Application and check "Unknown sources"
Open the package link above using Android Browser

or type "adb install NativeExe-*.apk" in your PC if you have Android SDK.

↑

How can I run UNIX commands in Android App? †

You can use Runtime.exec() in standard Java. Here's sample code to run /system/bin/ls /sdcard in Android App:

try {

    // Executes the command.

    Process process = Runtime.getRuntime().exec("/system/bin/ls /sdcard");

    // Reads stdout.

    // NOTE: You can write to stdin of the command using

    //       process.getOutputStream().

    BufferedReader reader = new BufferedReader(

            new InputStreamReader(process.getInputStream()));

    int read;

    char[] buffer = new char[4096];

    StringBuffer output = new StringBuffer();

    while ((read = reader.read(buffer)) > 0) {

        output.append(buffer, 0, read);

    }

    reader.close();

    // Waits for the command to finish.

    process.waitFor();

    return output.toString();

} catch (IOException e) {

    throw new RuntimeException(e);

} catch (InterruptedException e) {

    throw new RuntimeException(e);

}

This code is based on this article. Thanks yussi to let me know this by comment.

↑

OK, but how can I put my own native executable in Android App? †

First, you need to cross-compile your native executable for ARM.

Here's a way (dynamic link version). Or you can use Scratchbox (Japanese).

If you get a file with a format like this, it's probably OK:

% file yourapp

yourapp: ELF -bit LSB executable, ARM, version  (SYSV), for GNU/Linux 2.6., statically linked, not stripped

You have three ways to put the binary to the phone:

From Android Java app, using assets folder (by fnerg in comment below)
- Include the binary in the assets folder.
- Use getAssets().open("YourBinaryHere") to get an InputStream.
- Write it to /data/data/app-package-name (e.g. /data/data/net.gimite.nativeexe), where your application has access to write files and make it executable.
- Run "/system/bin/chmod 744 /data/data/app-package-name/yourapp" using the code above.
- Run your executable using the code above.

From Android Java app, downloading via HTTP (which I use in my demo application above)
- Dowload the executable using HTTP and put it to /data/data/app-package-name (e.g. /data/data/net.gimite.nativeexe), where your application has access to write files and make it executable. You can use standard Java FileOutputStream to write files there.
- Run "/system/bin/chmod 744 /data/data/app-package-name/yourapp" using the code above.
- Run your executable using the code above.

By adb (needs SDK and root)
- If you want to put the executable to YOUR phone connected with adb command in Android SDK and you have root, you can put the executable by:

% adb shell

$ su

# mkdir /data/tmp

# chmod  /data/tmp

# exit

$ exit

% adb push yourapp /data/tmp

% adb shell

$ chmod  /data/tmp/yourapp

$ /data/tmp/yourapp

Note that you cannot make files executable in /sdcard.