为什么在 android14 上找不到 boolean android.util.Log.isLoggable 的实现？

Question

我试图在 zygote 启动时从 JNI 加载我的 apk。在 android14 上遇到错误

No implementation found for boolean android.util.Log.isLoggable

，但在 android 13 上运行良好。

我发现它已经加载了

libandroid_runtime.log

。实现应该位于那里。

我这是怎么了？

04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693] Aborting thread:
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693] "main" prio=10 tid=1 Runnable
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   | group="" sCount=0 ucsCount=0 flags=0 obj=0x12c021d8 self=0xb400007d57689380
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   | sysTid=8651 nice=-20 cgrp=default sched=0/0 handle=0x7e4ed56448
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   | state=R schedstat=( 569334530 51221982 319 ) utm=41 stm=15 core=2 HZ=100
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   | stack=0x7ff3c32000-0x7ff3c34000 stackSize=8188KB
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   | held mutexes= "abort lock" "mutator lock"(shared held)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #00 pc 005c0a38  /apex/com.android.art/lib64/libart.so (art::DumpNativeStack+108) (BuildId: 8bf95d828d83d33315a6ec6a35ddc35f)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #01 pc 005aa3f4  /apex/com.android.art/lib64/libart.so (art::Thread::DumpStack const+804) (BuildId: 8bf95d828d83d33315a6ec6a35ddc35f)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #02 pc 0093670c  /apex/com.android.art/lib64/libart.so (art::Thread::DumpStack const+96) (BuildId: 8bf95d828d83d33315a6ec6a35ddc35f)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #03 pc 00921c1c  /apex/com.android.art/lib64/libart.so (art::AbortState::DumpThread const+56) (BuildId: 8bf95d828d83d33315a6ec6a35ddc35f)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #04 pc 0091a9cc  /apex/com.android.art/lib64/libart.so (art::Runtime::Abort+888) (BuildId: 8bf95d828d83d33315a6ec6a35ddc35f)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #05 pc 00019198  /apex/com.android.art/lib64/libbase.so (android::base::SetAborter::$_0::__invoke+80) (BuildId: 0f50f9c699c6af5881c3be1df5f8ebf2)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #06 pc 00018720  /apex/com.android.art/lib64/libbase.so (android::base::LogMessage::~LogMessage+352) (BuildId: 0f50f9c699c6af5881c3be1df5f8ebf2)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #07 pc 002f0ca0  /apex/com.android.art/lib64/libart.so (art::ClassLinker::FindClass+7708) (BuildId: 8bf95d828d83d33315a6ec6a35ddc35f)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #08 pc 0063281c  /apex/com.android.art/lib64/libart.so (art::JNI<true>::FindClass+656) (BuildId: 8bf95d828d83d33315a6ec6a35ddc35f)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #09 pc 000df254  /system/lib64/libandroid_runtime.so (jniRegisterNativeMethods+68) (BuildId: db8e21c9dd3921811f79cfb920d320bc)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #10 pc 000df1bc  /system/lib64/libandroid_runtime.so (android::register_com_android_internal_os_RuntimeInit+68) (BuildId: db8e21c9dd3921811f79cfb920d320bc)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #11 pc 000e3490  /system/lib64/libandroid_runtime.so (android::AndroidRuntime::startReg+64) (BuildId: db8e21c9dd3921811f79cfb920d320bc)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #12 pc 000e31a0  /system/lib64/libandroid_runtime.so (android::AndroidRuntime::start+496) (BuildId: db8e21c9dd3921811f79cfb920d320bc)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #13 pc 00002580  /system/bin/app_process64 (main+1224) (BuildId: af111bda59ddc4b8b33df988040c43b6)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   native: #14 pc 00054580  /apex/com.android.runtime/lib64/bionic/libc.so (__libc_init+104) (BuildId: 3d07239ca249ec10f6b9ffcbac96d553)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   (no managed stack frames)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693] Pending exception java.lang.UnsatisfiedLinkError: No implementation found for boolean android.util.Log.isLoggable(java.lang.String, int) (tried Java_android_util_Log_isLoggable and Java_android_util_Log_isLoggable__Ljava_lang_String_2I) - is the library loaded, e.g. System.loadLibrary?
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   at boolean android.util.Log.isLoggable(java.lang.String, int) (Log.java:-2)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   at void android.app.Instrumentation.<clinit>() (Instrumentation.java:103)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   at java.lang.Class java.lang.Class.classForName(java.lang.String, boolean, java.lang.ClassLoader) (Class.java:-2)
04-29 01:35:38.389  8651  8651 F zygote64: runtime.cc:693]   at java.lang.Class java.lang.Class.forName(java.lang.String, boolean, java.lang.ClassLoader) (Class.java:607)

Answer 1

Android的好处就是可以去读源码。 这是

android::register_com_android_internal_os_RuntimeInit

:

int register_com_android_internal_os_RuntimeInit(JNIEnv* env)
{
    const JNINativeMethod methods[] = {
            {"nativeFinishInit", "()V",
             (void*)com_android_internal_os_RuntimeInit_nativeFinishInit},
            {"nativeSetExitWithoutCleanup", "(Z)V",
             (void*)com_android_internal_os_RuntimeInit_nativeSetExitWithoutCleanup},
    };
    return jniRegisterNativeMethods(env, "com/android/internal/os/RuntimeInit",
        methods, NELEM(methods));
}

这是在

android::startReg

中循环调用的众多函数中的第一个：

static const RegJNIRec gRegJNI[] = {
        REG_JNI(register_com_android_internal_os_RuntimeInit), // We are here
        ...
        REG_JNI(register_android_util_Log), // This function associates `android.util.Log#isLoggable` with a native function pointer
        ...
};

出于某种原因（这不是我可以为您重现的内容），您的

FindClass

调用决定记录某些内容，但

register_android_util_Log

尚未有机会注册

android.util.Log#isLoggable

。

如果您想进一步调查这一点，您需要将调试器附加到您的程序并找出

art::ClassLinker::FindClass+7708

内部的堆栈帧决定记录什么内容。