Inline Hook Android

hook.c

#include <stdio.h>
#include <jni.h>
#include <android/log.h>
#include <dlfcn.h>
#include <sys/types.h>
#include <stdlib.h>
//#include "TKHooklib.h"

#define LOG_TAG "HOOK"
#define LOGI(...)  __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
#define LOGE(...)  __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)

typedef int (*TK_InlineHookFunction)(void *, void *, void** );
TK_InlineHookFunction pTK_InlineHookFunction_t = NULL;

char *getMoney = "_ZN7LKModel8getMoneyEv";

int (*orig_getMoney)(void);
int hook_getMoney(void)
{
    LOGI("getMoney()");
    return 1337;
}

void* lookup_symbol(char* libraryname, char* symbolname)
{
    void *imagehandle = dlopen(libraryname, RTLD_GLOBAL | RTLD_NOW);
    if (imagehandle != NULL)
    {
        dlerror(); //clear
        void * sym = dlsym(imagehandle, symbolname);
        if (sym != NULL)
        {
            return sym;
        }
        else
        {
            LOGI("(lookup_symbol) %s", symbolname);
            LOGE("dlerror: %s", dlerror());
            return NULL;
        }
    }
    else
    {
        LOGI("(lookup_symbol) dlerror: %s",dlerror());
        return NULL;
    }
}

void doHook()
{
    void * pGetMoney = lookup_symbol("libcocos2dlua.so", getMoney);

    int ret = pTK_InlineHookFunction_t(pGetMoney, (void*)&hook_getMoney, (void**)&orig_getMoney);
    LOGI("Hook Money %s", ret == 0 ? "success" : "failed");
}

jint JNI_OnLoad(JavaVM* vm, void* reserved)
{
    jint result = -1;
    void *handle;
    
    handle = dlopen("/data/data/com.nova.DemonSouls/lib/libTKHooklib.so", RTLD_NOW);
    if (handle == NULL)
    {
        LOGE("dlopen [%s TKHooklib.so]", dlerror());
	goto exit;
    }

    dlerror();
    
    pTK_InlineHookFunction_t = dlsym(handle, "TK_InlineHookFunction");
    if (pTK_InlineHookFunction_t == NULL)
    {
        LOGE("dlsym [%s TK_InlineHookFunction]", dlerror());
        goto exit;
    }
    
    doHook();

    result = JNI_VERSION_1_4;
exit:
    return result;
}