This is a project for mini-tracing based on refs/tags/android-5.1.1_r3.

Now we support fuzzing actions.


  1. Checkout the all source code of Android. Note that we currently require 5.1.1_r3.
  2. Follow the guidelines in Downloading and Building section.

    source build/
    launch aosp_arm-eng

    hmm will print a help message on how to build a single module in the source tree.

    Invoke ". build/" from your shell to add the following functions to your environment:
    - lunch:   lunch <product_name>-<build_variant>
    - tapas:   tapas [<App1> <App2> ...] [arm|x86|mips|armv5|arm64|x86_64|mips64] [eng|userdebug|user]
    - croot:   Changes directory to the top of the tree.
    - m:       Makes from the top of the tree.
    - mm:      Builds all of the modules in the current directory, but not their dependencies.
    - mmm:     Builds all of the modules in the supplied directories, but not their dependencies.
               To limit the modules being built use the syntax: mmm dir/:target1,target2.
    - mma:     Builds all of the modules in the current directory, and their dependencies.
    - mmma:    Builds all of the modules in the supplied directories, and their dependencies.
    - cgrep:   Greps on all local C/C++ files.
    - ggrep:   Greps on all local Gradle files.
    - jgrep:   Greps on all local Java files.
    - resgrep: Greps on all local res/*.xml files.
    - sgrep:   Greps on all local source files.
    - godir:   Go to the directory containing a file.
    Look at the source to view more functions. The complete list is:
    adb_get_product_device adb_get_traced_by addcompletions add_lunch_combo cgrep check_product check_variant choosecombo chooseproduct choosetype choosevariant core coredump_enable coredump_setup cproj croot findmakefile gdbclient gdbclient_old gdbwrapper get_abs_build_var getbugreports get_build_var getdriver getlastscreenshot get_make_command getprebuilt getscreenshotpath getsdcardpath get_symbols_directory gettargetarch gettop ggrep godir hmm is isviewserverstarted jgrep key_back key_home key_menu lunch _lunch m make mangrep mgrep mm mma mmm mmma pez pid printconfig print_lunch_menu qpid resgrep runhat runtest sepgrep set_java_home setpaths set_sequence_number set_stuff_for_environment settitle sgrep smoketest stacks startviewserver stopviewserver systemstack tapas tracedmdump treegrep

    Once you have built all dependencies, you can build by invoke make libart in the top directory.
    3. As we want to build art, we can change the directory into the art and invoke mma.
    4. Then, you will find a command art in your path, type which art to check it. This is a x86 version in your host machine, e.g., ubuntu 14.04 for me.
    5. Next prepare a dex file to test art. Refer to this to learn how to prepare a dex file.
    6. As now we already have the art script to setup all environment variables, we can simple invoke art via art -cp classes.dex HelloWorld.


You should root your phone in order to replace the /system/lib/ with your custom build.
Currently, the custom can only be installed on a Nexus 5 with Android 5.1.1_r3.
Other platforms are not tested, but the code we added is quite small, only 170 lines.
You can download the Android Open Source Project for your phone and then apply the patch to the art.


  1. Make sure adb is in your PATH.
  2. Log into your phone via adb shell, and switch to root via su.
  3. Launch an apps in your phone. You could start a process via adb in command line.
  4. Get the pid of your phone via ps | grep <your app>
  5. At first, MiniTrace is toggled off. Turn it on via kill -USR2 $PID.
    You can also start the MiniTrace via a configuration file. See below.
  6. Run your test script.
  7. Once the test has finished, turn off the MiniTrace via kill -USR2 $PID.
    The trace can only be written to the file at /sdcard/mini_tracing.log if your have manually toggle off MiniTrace.

Configuration and Log File

There are three files

  1. /sdcard/mini_trace_$ configuration
  2. /sdcard/mini_trace_$uid_info.log: visited methods and fields, and coverage information
  3. /sdcard/mini_trace_$uid_data.bin: binary trace data

A parser for these files can be found at minitrace in android-toolkit

Traced Events

We only plan to implement tracing in the interpreter.
We only force methods in the apps to be interpreted and we only guarantee to trace those events.
Other methods of the framework are not guaranteed to be traced.

  1. Method Enter/Exit
  2. Instance Field Get/Put
  3. Static Field Get/Put
  4. Monitor Enter/Exit
  5. Array Element Load/Store
  6. Coverage


As all apps are started by ActivityManagerService and forked from the zygote,
we cannot specify startup options for the ART.
Therefore, we have to read options in another way.

Currently, we support two ways to trigger MiniTrace

  1. Use SIGUSR2 when we can get the pid.
  2. Use a configuration file at /sdcard/mini_trace_$

MiniTrace will first check whether the file exists.

Apps without SDCARD_RW Permission

Many apps have no permission to read and write SDCARD.
Therefore, we also support put the same configure file at /data.
Besides, some priority should be set.

  1. Touch three files for config, info and data for mini trace
    1. /data/mini_trace_$
    2. /data/mini_trace_$uid_info.log
    3. /data/mini_trace_$uid_data.bin
  2. Set the owner of these three files to the apps-under-test by chown. For example, the Calculator has a user name u0_a31.
    This can be checked the owner for directory /data/data/<package-name>/cache.
  3. Set selinux to permissive mode

    adb shell su -c setenforce 0

Configuration File Format

One line an options.


  1. off
  2. MethodEvent
  3. FieldEvent
  4. MonitorEvent (Not implement yet!)
  5. DoCoverage

If the file is empty, then all available options are opened.


An example of configuration file is shown here:

verbose 0
throw 30
Lcom/android/okio/RealBufferedSource$1; read ()I 1000000 java/io/IOException 0 
Lcom/android/okio/RealBufferedSource$1; read ([BII)I 2000000 java/io/IOException 0

Note the trailing white space.