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Commit fc667834 authored by Yifan Hong's avatar Yifan Hong
Browse files

AndroidRuntime: Expose javaAttachThread / javaDetachThread. 

Add a new header library, libandroid_runtime_threads_headers,
that exposes javaAttachThread / javaDetachThread.

Also change the return value from int to bool, since the client
may not know about JNI_OK.

Test: boots
Bug: 190450693
Change-Id: Ifedd34a8c8a1847d89c9f2f7919ff7e4b13b7446
parent 7405010f

core/jni/Android.bp

+16 −0
Original line number Diff line number Diff line
@@ -297,6 +297,7 @@ cc_library_shared { 
            header_libs: [

                "bionic_libc_platform_headers",

                "dnsproxyd_protocol_headers",

                "libandroid_runtime_threads_headers",

            ],

        },

        host: {
@@ -338,3 +339,18 @@ cc_library_shared { 
        never: true,

    },

}



cc_library_headers {

    name: "libandroid_runtime_threads_headers",

    host_supported: true,

    vendor_available: true,

    // TODO(b/153609531): remove when libbinder is not native_bridge_supported

    native_bridge_supported: true,

    // Allow only modules from the following list to create threads that can be

    // attached to the JVM. This list should be a subset of the dependencies of

    // libandroid_runtime.

    visibility: [

        "//frameworks/native/libs/binder",

    ],

    export_include_dirs: ["include_threads"],

}

core/jni/AndroidRuntime.cpp

+15 −15
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <android-base/properties.h>

#include <android/graphics/jni_runtime.h>

#include <android_runtime/AndroidRuntime.h>

#include <android_runtime/threads.h>

#include <assert.h>

#include <binder/IBinder.h>

#include <binder/IPCThreadState.h>
@@ -1325,14 +1326,15 @@ void AndroidRuntime::onVmCreated(JNIEnv* env) 
    return env;

}



extern "C" {



/*

 * Makes the current thread visible to the VM.

 *

 * The JNIEnv pointer returned is only valid for the current thread, and

 * thus must be tucked into thread-local storage.

 */

static int javaAttachThread(const char* threadName, JNIEnv** pEnv)

{

bool androidJavaAttachThread(const char* threadName) {

    JavaVMAttachArgs args;

    JavaVM* vm;

    jint result;
@@ -1344,18 +1346,17 @@ static int javaAttachThread(const char* threadName, JNIEnv** pEnv) 
    args.name = (char*) threadName;

    args.group = NULL;



    result = vm->AttachCurrentThread(pEnv, (void*) &args);

    if (result != JNI_OK)

        ALOGI("NOTE: attach of thread '%s' failed\n", threadName);

    JNIEnv* env;

    result = vm->AttachCurrentThread(&env, (void*)&args);

    if (result != JNI_OK) ALOGI("NOTE: attach of thread '%s' failed\n", threadName);



    return result;

    return result == JNI_OK;

}



/*

 * Detach the current thread from the set visible to the VM.

 */

static int javaDetachThread(void)

{

bool androidJavaDetachThread(void) {

    JavaVM* vm;

    jint result;
@@ -1363,11 +1364,12 @@ static int javaDetachThread(void) 
    assert(vm != NULL);



    result = vm->DetachCurrentThread();

    if (result != JNI_OK)

        ALOGE("ERROR: thread detach failed\n");

    return result;

    if (result != JNI_OK) ALOGE("ERROR: thread detach failed\n");

    return result == JNI_OK;

}



} // extern "C"



/*

 * When starting a native thread that will be visible from the VM, we

 * bounce through this to get the right attach/detach action.
@@ -1378,18 +1380,16 @@ static int javaDetachThread(void) 
    void* userData = ((void **)args)[1];

    char* name = (char*) ((void **)args)[2];        // we own this storage

    free(args);

    JNIEnv* env;

    int result;



    /* hook us into the VM */

    if (javaAttachThread(name, &env) != JNI_OK)

        return -1;

    if (!androidJavaAttachThread(name)) return -1;



    /* start the thread running */

    result = (*(android_thread_func_t)start)(userData);



    /* unhook us */

    javaDetachThread();

    (void)androidJavaDetachThread();

    free(name);



    return result;

core/jni/include_threads/android_runtime/threads.h

0 → 100644
+30 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2021 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.

 */



// Manages the interaction between threads and the Android Runtime. If these symbols do not exist

// at runtime, it means the current process does not link to libandroid_runtime.



#pragma once



extern "C" {



// Attach current thread to JVM. Return true if successful, false otherwise.

bool androidJavaAttachThread(const char* threadName);



// Detach current thread to JVM. Return true if successful, false otherwise.

bool androidJavaDetachThread();



} // extern "C"