开发demo

新建native项目，实现log打印字符串。
下载地址：https://download.csdn.net/download/u013170888/89698015

#include <android/log.h>
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, "JNI_LOG", __VA_ARGS__)

extern "C" JNIEXPORT jstring JNICALL
Java_com_android_nativedemo3_MainActivity_stringFromJNI(
        JNIEnv* env,
        jobject /* this */) {

    std::string hexHello = StrToHex("Hello from C++");
    std::string hello = HexToStr(hexHello);
    LOGI("hexHello: %s",hexHello.c_str());
    LOGI("hello: %s",hello.c_str());
    return env->NewStringUTF(hello.c_str());
}

运行一下看输出日志：

Hook log打印内容

frida hook 脚本：
注意参数数量
下载地址：https://download.csdn.net/download/u013170888/89698021

function hook_native() {
    var addr = Module.getExportByName("liblog.so", "__android_log_print")
    Interceptor.attach(addr, {
        onEnter: function (args) {
            console.log("args 0 = ", args[0])
            console.log("args 1 = ", args[1].readCString())
            console.log("args 2 = ", args[2].readCString())
            console.log("args 3 = ", args[3].readCString())
        }, onLeave: function (retval) {
            console.log("retval = ", retval)
        }
    })
}
setImmediate(hook_native)

运行打印结果：