The process of Android loading so

SOURCE version: Android-4.4.4_r1

Take [java.lang.Runtime-load ()] as an example to illustrate (Loadliabrary () Finally and load () the same, interested can self-analysis), the corresponding Android source code in the [srcandroid/libcore/ luni/src/main/java/java/lang/runtime.java/home/shanyu/srcandroid/libcore/luni/src/main/java/java/lang/ Runtime.java],

Start with 320 rows.

    /** * Loads and links The dynamic library is identified through the * specified path. This method was similar to {@link #loadLibrary (String)}, * But it accepts a full path specification whereas {@code load     Library} just * accepts the name of the library to load.     * * @param pathName * The absolute (platform dependent) path to the library to load.     * @throws Unsatisfiedlinkerror * If the library can not be loaded. */     Public voidload (String pathName) {load (PathName, Vmstack.getcallingclassloader ()); }    /** Loads and links the given library without security checks. */    voidLoad (String pathName, ClassLoader loader) {if(PathName = =NULL) {            Throw NewNullPointerException ("PathName = = NULL"); } String Error=doload (pathName, loader); if(Error! =NULL) {            Throw NewUnsatisfiedlinkerror (Error); }    }

Finally, the Doload (String name, ClassLoader loader) function is called, and the function is still in the Runtime.java file:

    Privatestring Doload (string name, ClassLoader loader) {//Android Apps is forked from the zygote, so they can ' t has a custom ld_library_path,//which means that by the default an app's shared library directory is not on Ld_library_path. //the Pathclassloader set up by frameworks/base knows the appropriate path, so we can load//libraries with no dependencies just fine, but a app that have multiple libraries that//depend on the needed to the load them in Most-dependent-first order. //we added API to Android's dynamic linker so We can update the library path used for//The currently-running process. We pull the desired path out of the A ClassLoader here//and Pass it to nativeload so, it can call the private dynamic linker API. //We didn ' t just change frameworks/base to update the Ld_library_path once at the//beginning because multiple APKs can run in the same process and third party code can//Use the its own basedexclassloader. //we didn ' t just add a Dlopen_with_custom_ld_library_path call because We wanted any//Dlopen (3) calls made from a. So's jni_onload to work too. //So, find out what the native Library search path was for the ClassLoader in question ...String Ldlibrarypath =NULL; if(Loader! =NULL&&Loader instanceof Basedexclassloader) {Ldlibrarypath=((basedexclassloader) loader). Getldlibrarypath (); }        //Nativeload should is synchronized so there ' s only one ld_library_path in use regardless//of how many classloaders is in the system, but Dalvik doesn ' t support synchronized//internal natives.Synchronized ( This) {            returnnativeload (name, loader, ldlibrarypath); }    }    //Todo:should is synchronized, but Dalvik doesn ' t support synchronized internal natives.    Private StaticNative string Nativeload (string filename, ClassLoader loader, string ldlibrarypath);

The final call to the "string nativeload (string filename, ClassLoader loader, string ldlibrarypath)" function, a native function, is defined in [Srcandroid/ Dalvik/vm/native/java_lang_runtime.cpp] file. Start with 64 lines:

/** Static string Nativeload (string filename, ClassLoader loader, string ldlibrarypath) * Load the specified full pat h as a dynamic library filled with * jni-compatible methods. Returns null on success, or a failure * message on failure. */Static voidDalvik_java_lang_runtime_nativeload (Constu4*args, Jvalue*PResult) {Stringobject* Filenameobj = (stringobject*) args[0]; Object* ClassLoader = (object*) args[1]; Stringobject* Ldlibrarypathobj = (stringobject*) args[2]; ASSERT (Filenameobj!=NULL); Char* FileName =dvmcreatecstrfromstring (filenameobj); if(Ldlibrarypathobj! =NULL) {        Char* Ldlibrarypath =dvmcreatecstrfromstring (ldlibrarypathobj); void* sym = Dlsym (Rtld_default,"Android_update_ld_library_path"); if(Sym! =NULL) {typedefvoid(*FN) (Const Char*); Fn Android_update_ld_library_path= reinterpret_cast<fn>(SYM); (*Android_update_ld_library_path)        (Ldlibrarypath); } Else{Aloge ("Android_update_ld_library_path not found; Dependencies would not work!"); }         Free(Ldlibrarypath); } stringobject* result =NULL; Char* Reason =NULL; BOOLSuccess = Dvmloadnativecode (FileName, ClassLoader, &reason); if(!success) {        Const Char* msg = (reason! = NULL)? Reason:"Unknown Failure"; Result=dvmcreatestringfromcstr (msg); Dvmreleasetrackedalloc ((Object*) result, NULL); }     Free(reason);  Free(FileName); Return_ptr (result);}

or pass value + check, then execute [bool success = Dvmloadnativecode (FileName, ClassLoader, &reason);], look at the code for Dvmloadnativecode (...), located at V M/native.cpp # 301 lines.

The process of Android loading so