bool HookDalvikMethod(jmethodID jmethod){
Method *method = (Method*)jmethod;
//关键!!将目标方法修改为native方法
SET_METHOD_FLAG(method, ACC_NATIVE);
int argsSize = dvmComputeMethodArgsSize(method);
if (!dvmIsStaticMethod(method))
argsSize++;
method->registersSize = method->insSize = argsSize;
if (dvmIsNativeMethod(method)) {
method->nativeFunc = dvmResolveNativeMethod;
method->jniArgInfo = computeJniArgInfo(&method->prototype);
}
}
extern "C" int hook_dvm(JNIEnv *env, struct hook_java_args *args) {
jclass clz, tmp;
jmethodID jm;
bool isStatic = false;
struct hook_java_args *ha = NULL;
Method *method;
int argsSize;
if (loadDVM()) {
LOGE("hook_dvm: loadDVM() failed");
return -1;
}
if ((args->prev || args->post) && args->func) {
LOGE("hook_dvm: invalid argument");
return -1;
}
tmp = hsdk_find_clz(env, args->clz);
if (tmp == NULL) {
LOGE("hook_dvm: class `%s\' not found", args->clz);
return -1;
}
// XXX: find_clz3w
// saying given clz is invalid
//W/dalvikvm( 8493): Invalid indirect reference 0x41cd9338 in decodeIndirectRef
//E/dalvikvm( 8493): VM aborting
clz = (jclass) env->NewGlobalRef(tmp);
env->DeleteLocalRef(tmp);
if (clz == NULL) {
LOGE("hook_dvm: unable to ref clz");
return -1;
}
jm = env->GetMethodID(clz, args->mtd, args->sig);
if (jm == NULL) {
if (env->ExceptionOccurred())
env->ExceptionClear();
jm = env->GetStaticMethodID(clz, args->mtd, args->sig);
if (env->ExceptionOccurred())
env->ExceptionClear();
if (jm == NULL) {
LOGE("hook_dvm: method `%s\' with sig `%s\' not found", args->mtd, args->sig);
env->DeleteGlobalRef(clz);
return -1;
}
isStatic = true;
}
// XXX: leak the global ref so GC won't recycle the class then Member will be always valid?
env->DeleteGlobalRef(clz);
method = (Method *) jm;
if ((method->nativeFunc == hsdk_bridge_func) ||
(method->nativeFunc == dvmCallJNIMethod && method->insns == args->func)) {
LOGD("hook_dvm: already hooked");
return 0;
}
// hook
args->old = calloc(1, sizeof(*method));
if (args->old)
memcpy(args->old, jm, sizeof(*method));
if (!args->func) {
ha = (struct hook_java_args *) calloc(1, sizeof(*ha));
if (!ha) {
LOGE("hook_dvm: calloc failed");
if (args->old) {
free(args->old);
args->old = 0;
}
return -1;
}
ha->clz = strdup(args->clz);
ha->mtd = strdup(args->mtd);
ha->sig = strdup(args->sig);
ha->prev = args->prev;
ha->post = args->post;
}
argsSize = dexProtoComputeArgsSize(&method->prototype);
if (!isStatic)
argsSize += 1;
method->registersSize = argsSize;
method->insSize = argsSize;
method->outsSize = 0;
method->insns = NULL;
method->jniArgInfo = computeJniArgInfo(&method->prototype);
if (!args->func) {
method->insns = (const u2*) ha;
method->nativeFunc = hsdk_bridge_func;
} else {
dvmUseJNIBridge(method, args->func);
}
SET_METHOD_FLAG(method, ACC_NATIVE);
if (args->func) {
LOGD("hook_dvm: %sL%s;%s->%s => %p", isStatic ? "static " : "",
args->clz, args->mtd, args->sig, args->func);
}
return 0;
}
