"Analysis" Dalvik virtual machine boot process (iii)

SOURCE version: ANDROID-4.4.4_R2

Tips: Most of the analysis is directly annotated within the code.

Related articles:

"Analysis" Dalvik virtual machine boot process (i)

"Analysis" Dalvik virtual machine boot process (ii)

In the AndroidRuntime::start call AndroidRuntime::startVm function to start the virtual machine, and then call the AndroidRuntime::startReg function to register the Android function:

/* * Register the Android local function with the VM. * Register Android Native functions with the VM.    *//*static*/int Androidruntime::startreg (jnienv* env) {//This function doesn't know what it's for!  /* * This hook is causes all future threads created in this process to being * attached to the JAVAVM.     (This needs to go away in favor of JNI * Attach calls.)    */Androidsetcreatethreadfunc ((ANDROID_CREATE_THREAD_FN) javacreatethreadetc);    ALOGV ("---registering native functions---\ n");  /* * Every "register" function calls one or more things that return * a local reference (e.g. findclass).   Because we haven ' t really * started the VM yet, they ' re all getting stored in the base frame * and never released.     Use Push/pop to manage the storage.    */Env->pushlocalframe (200);    Gregjni is a list of functions that register some local functions.        if (Register_jni_procs (Gregjni, Nelem (GREGJNI), env) < 0) {env->poplocalframe (NULL);    return-1;    } env->poplocalframe (NULL); Createjavathread ("Fubar", quIcktest, (void*) "Hello"); return 0;}

Gregjni:

static const REGJNIREC gregjni[] = {    ...    Reg_jni (Register_android_util_log),    ...};

Take REG_JNI(register_android_util_Log), the function register_jni_procsis called register_android_util_Log:

/* JNI registration. */static Jninativemethod gmethods[] = {/* name, signature, Funcptr */{"isloggable", "(ljava/lang/string;i) Z" , (void*) android_util_log_isloggable}, {"Println_native", "(iiljava/lang/string;    ljava/lang/string;) I ", (void*) android_util_log_println_native},};int register_android_util_log (JNIEnv* env) {    Jclass clazz = Env->findclass ("Android/util/log");        if (clazz = = NULL) {aloge ("Can ' t find Android/util/log");    return-1;    } levels.verbose = Env->getstaticintfield (Clazz, Env->getstaticfieldid (clazz, "verbose", "I"));    Levels.debug = Env->getstaticintfield (Clazz, Env->getstaticfieldid (clazz, "Debug", "I"));    Levels.info = Env->getstaticintfield (Clazz, Env->getstaticfieldid (clazz, "info", "I"));    Levels.warn = Env->getstaticintfield (Clazz, Env->getstaticfieldid (Clazz, "warn", "I"));    Levels.error = Env->getstaticintfield (Clazz, Env->getstaticfieldid (clazz, "error", "I")); Levels.assert = Env->getstaticintfield (Clazz, Env->getstaticfieldid (Clazz, "ASSERT", "I")); Return Androidruntime::registernativemethods (env, "Android/util/log", Gmethods, Nelem (Gmethods));}

the Register_android_util_log function java.util.Logclass is registered in the gMethodsthe two methods in: Isloggable and println_native.
But when I opened Eclipse, looking at the source code in the log class did not have these two classes, I used Jd-jui opened the Android SDK 4.4 of the jar package, found the native method isloggable, but still did not find Println_ Native method, I guess the classes and methods in the Android SDK are after all 不全的!

Conclusion: There are many places that are not analyzed, such as Dalvik virtual machine parameter analysis, Dvmstartup function, the function of a large number of initialization functions.

"Analysis" Dalvik virtual machine boot process (iii)