Merge "Merge "Add JVMTI agent to dump/reset JaCoCo coverage information" am:...

//

// Copyright (C) 2019 The Android Open Source Project

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//      http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

//

// Build variants {target,host} x {32,64}

cc_library {

    name: "libdumpcoverage",

    srcs: ["dump_coverage.cc"],

    header_libs: [

        "libopenjdkjvmti_headers",

    ],

    host_supported: true,

    shared_libs: [

        "libbase",

    ],

}

# dumpcoverage

libdumpcoverage.so is a JVMTI agent designed to dump coverage information for a process, where the binaries have been instrumented by JaCoCo. JaCoCo automatically starts recording data on process start, and we need a way to trigger the resetting or dumping of this data.

The JVMTI agent is used to make the calls to JaCoCo in its process.

# Usage

Note that these examples assume you have an instrumented build (userdebug_coverage). Here is, for example, how to dump coverage information regarding the default clock app. First some setup is necessary:

```

adb root # necessary to copy files in/out of the /data/data/{package} folder

adb shell 'mkdir /data/data/com.android.deskclock/folder-to-use'

```

Then we can run the command to dump the data:

```

adb shell 'am attach-agent com.android.deskclock /system/lib/libdumpcoverage.so=dump:/data/data/com.android.deskclock/folder-to-use'

```

We can also reset the coverage information with

```

adb shell 'am attach-agent com.android.deskclock /system/lib/libdumpcoverage.so=reset'

```

then perform more actions, then dump the data again. To get the files, we can get

```

adb pull /data/data/com.android.deskclock/folder-to-use ~/path-on-your-computer

```

And you should have timestamped `.exec` files on your machine under the folder `~/path-on-your-computer`

# Details

In dump mode, the agent makes JNI calls equivalent to

```

Agent.getInstance().getExecutionData(/*reset = */ false);

```

and then saves the result to a file specified by the passed in directory

In reset mode, it makes a JNI call equivalent to

```

Agent.getInstance().reset();

```

// Copyright (C) 2018 The Android Open Source Project

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//      http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

//

#include <android-base/logging.h>

#include <jni.h>

#include <jvmti.h>

#include <string.h>

#include <atomic>

#include <ctime>

#include <fstream>

#include <iomanip>

#include <iostream>

#include <istream>

#include <memory>

#include <sstream>

#include <string>

#include <vector>

using std::get;

using std::tuple;

using std::chrono::system_clock;

namespace dump_coverage {

#define CHECK_JVMTI(x) CHECK_EQ((x), JVMTI_ERROR_NONE)

#define CHECK_NOTNULL(x) CHECK((x) != nullptr)

#define CHECK_NO_EXCEPTION(env) CHECK(!(env)->ExceptionCheck());

static JavaVM* java_vm = nullptr;

// Get the current JNI environment.

static JNIEnv* GetJNIEnv() {

  JNIEnv* env = nullptr;

  CHECK_EQ(java_vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6),

           JNI_OK);

  return env;

}

// Get the JaCoCo Agent class and an instance of the class, given a JNI

// environment.

// Will crash if the Agent isn't found or if any Java Exception occurs.

static tuple<jclass, jobject> GetJavaAgent(JNIEnv* env) {

  jclass java_agent_class =

      env->FindClass("org/jacoco/agent/rt/internal/Agent");

  CHECK_NOTNULL(java_agent_class);

  jmethodID java_agent_get_instance =

      env->GetStaticMethodID(java_agent_class, "getInstance",

                             "()Lorg/jacoco/agent/rt/internal/Agent;");

  CHECK_NOTNULL(java_agent_get_instance);

  jobject java_agent_instance =

      env->CallStaticObjectMethod(java_agent_class, java_agent_get_instance);

  CHECK_NO_EXCEPTION(env);

  CHECK_NOTNULL(java_agent_instance);

  return tuple(java_agent_class, java_agent_instance);

}

// Runs equivalent of Agent.getInstance().getExecutionData(false) and returns

// the result.

// Will crash if the Agent isn't found or if any Java Exception occurs.

static jbyteArray GetExecutionData(JNIEnv* env) {

  auto java_agent = GetJavaAgent(env);

  jmethodID java_agent_get_execution_data =

      env->GetMethodID(get<0>(java_agent), "getExecutionData", "(Z)[B");

  CHECK_NO_EXCEPTION(env);

  CHECK_NOTNULL(java_agent_get_execution_data);

  jbyteArray java_result_array = (jbyteArray)env->CallObjectMethod(

      get<1>(java_agent), java_agent_get_execution_data, false);

  CHECK_NO_EXCEPTION(env);

  return java_result_array;

}

// Gets the filename to write execution data to

//  dirname: the directory in which to place the file

//  outputs <dirname>/YYYY-MM-DD-HH-MM-SS.SSS.exec

static std::string GetFilename(const std::string& dirname) {

  system_clock::time_point time_point = system_clock::now();

  auto seconds = std::chrono::time_point_cast<std::chrono::seconds>(time_point);

  auto fractional_time = time_point - seconds;

  auto millis = std::chrono::duration_cast<std::chrono::milliseconds>(fractional_time);

  std::time_t time = system_clock::to_time_t(time_point);

  auto tm = *std::gmtime(&time);

  std::ostringstream oss;

  oss

    << dirname

    << "/"

    << std::put_time(&tm, "%Y-%m-%d-%H-%M-%S.")

    << std::setfill('0') << std::setw(3) << millis.count()

    << ".ec";

  return oss.str();

}

// Writes the execution data to a file

//  data, length: represent the data, as a sequence of bytes

//  dirname: directory name to contain the file

//  returns JNI_ERR if there is an error in writing the file, otherwise JNI_OK.

static jint WriteFile(const char* data, int length, const std::string& dirname) {

  auto filename = GetFilename(dirname);

  LOG(INFO) << "Writing file of length " << length << " to '" << filename

            << "'";

  std::ofstream file(filename, std::ios::binary);

  if (!file.is_open()) {

    LOG(ERROR) << "Could not open file: '" << filename << "'";

    return JNI_ERR;

  }

  file.write(data, length);

  file.close();

  if (!file) {

    LOG(ERROR) << "I/O error in reading file";

    return JNI_ERR;

  }

  LOG(INFO) << "Done writing file";

  return JNI_OK;

}

// Grabs execution data and writes it to a file

//  dirname: directory name to contain the file

//  returns JNI_ERR if there is an error writing the file.

// Will crash if the Agent isn't found or if any Java Exception occurs.

static jint Dump(const std::string& dirname) {

  LOG(INFO) << "Dumping file";

  JNIEnv* env = GetJNIEnv();

  jbyteArray java_result_array = GetExecutionData(env);

  CHECK_NOTNULL(java_result_array);

  jbyte* result_ptr = env->GetByteArrayElements(java_result_array, 0);

  CHECK_NOTNULL(result_ptr);

  int result_len = env->GetArrayLength(java_result_array);

  return WriteFile((const char*) result_ptr, result_len, dirname);

}

// Resets execution data, performing the equivalent of

//  Agent.getInstance().reset();

//  args: should be empty

//  returns JNI_ERR if the arguments are invalid.

// Will crash if the Agent isn't found or if any Java Exception occurs.

static jint Reset(const std::string& args) {

  if (args != "") {

    LOG(ERROR) << "reset takes no arguments, but received '" << args << "'";

    return JNI_ERR;

  }

  JNIEnv* env = GetJNIEnv();

  auto java_agent = GetJavaAgent(env);

  jmethodID java_agent_reset =

      env->GetMethodID(get<0>(java_agent), "reset", "()V");

  CHECK_NOTNULL(java_agent_reset);

  env->CallVoidMethod(get<1>(java_agent), java_agent_reset);

  CHECK_NO_EXCEPTION(env);

  return JNI_OK;

}

// Given a string of the form "<a>:<b>" returns (<a>, <b>).

// Given a string <a> that doesn't contain a colon, returns (<a>, "").

static tuple<std::string, std::string> SplitOnColon(const std::string& options) {

  size_t loc_delim = options.find(':');

  std::string command, args;

  if (loc_delim == std::string::npos) {

    command = options;

  } else {

    command = options.substr(0, loc_delim);

    args = options.substr(loc_delim + 1, options.length());

  }

  return tuple(command, args);

}

// Parses and executes a command specified by options of the form

// "<command>:<args>" where <command> is either "dump" or "reset".

static jint ParseOptionsAndExecuteCommand(const std::string& options) {

  auto split = SplitOnColon(options);

  auto command = get<0>(split), args = get<1>(split);

  LOG(INFO) << "command: '" << command << "' args: '" << args << "'";

  if (command == "dump") {

    return Dump(args);

  }

  if (command == "reset") {

    return Reset(args);

  }

  LOG(ERROR) << "Invalid command: expected 'dump' or 'reset' but was '"

             << command << "'";

  return JNI_ERR;

}

static jint AgentStart(JavaVM* vm, char* options) {

  android::base::InitLogging(/* argv= */ nullptr);

  java_vm = vm;

  return ParseOptionsAndExecuteCommand(options);

}

// Late attachment (e.g. 'am attach-agent').

extern "C" JNIEXPORT jint JNICALL

Agent_OnAttach(JavaVM* vm, char* options, void* reserved ATTRIBUTE_UNUSED) {

  return AgentStart(vm, options);

}

// Early attachment.

extern "C" JNIEXPORT jint JNICALL

Agent_OnLoad(JavaVM* jvm ATTRIBUTE_UNUSED, char* options ATTRIBUTE_UNUSED, void* reserved ATTRIBUTE_UNUSED) {

  LOG(ERROR)

    << "The dumpcoverage agent will not work on load,"

    << " as it does not have access to the runtime.";

  return JNI_ERR;

}

}  // namespace dump_coverage