android hook native函數

大概2年前寫的代碼，今天突然要用到，找了半天，這裡記錄下

用到的庫: https://pan.baidu.com/s/1htuUQX2

#include <jni.h>
#include <string>
#include <dlfcn.h>

typedef  int  (*  pfnMSHookFunction)(void* result, void* a2, void** a3);

int Aaaaaa(jint a, jint b)
{

    int bRet = 0;
    bRet = a/3;
    return  bRet;
}

extern  "C"
JNIEXPORT

int  Java_aaa_aaa_MainActivity_test(jint a,jint b)
{
    FILE *fp = fopen("1.txt", "rb");
    if (0 != fp)
    {
        printf("111");
    }

  return   Aaaaaa(a, b);
}


typedef FILE*    (*pfnmyfopen)(const char *, const char *);
pfnmyfopen porg = 0;

//fake 函數
FILE    *myfopen(const char * name, const char * flag)
{
    FILE* fret = 0;
    fret =  porg(name,flag);
    return  fret;
}

//這裡用的是substrate
void initHook()
{
   void* phandle =dlopen("libhook.so",RTLD_NOW );
    pfnMSHookFunction pmsHook=(pfnMSHookFunction)dlsym(phandle,"MSHookFunction");
    pmsHook((void*)fopen,(void*)myfopen,(void**)&porg);


}

jint JNICALL JNI_OnLoad(JavaVM* vm, void* reserved)
{
    JNIEnv* env = 0;
    jint result = -1;

    if (vm->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK)
    {
        return -1;
    }

    initHook();

    result = JNI_VERSION_1_4;

    return result;
}