android调用C语言实现内存的读取与修改的方法示例

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<?xml version="1.0" encoding="utf-8"? 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:gravity="center"
  android:orientation="vertical" 

  <Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:onClick="btn" / 

  <TextView
    android:id="@+id/tv"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="~" / 

</LinearLayout 

package com.gs.jc;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

  private TextView textView;
  private JNI jni;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    jni = new JNI();
    textView = (TextView) findViewById(R.id.tv);
  }

  public void btn(View view) {
    textView.setText(String.valueOf(jni.searchMem()));
  }

}

package com.gs.jc;

public class JNI {

  static {
    System.loadLibrary("native-lib");
  }

	/*
	*定义native方法
	*调用C代码对应的方法
	*/
  public native int searchMem();
}

#include <jni.h 
#include <string 
#include <stdio.h 
#include <stdlib.h 
#include <fcntl.h 
#include <dirent.h 
#include <unistd.h 

static int fd = 0;

//查找游戏进程pid
int getPID(const char *pack_name) {
  int id = -1, pid = -1;
  DIR *dir = 0;
  FILE *file = 0;
  char filename[32] = {0};
  char cmdline[256] = {0};
  struct dirent *entry = 0;

  if (pack_name == NULL) {
    return -1;
  }

  dir = opendir("/proc");
  if (dir == NULL) {
    return -1;
  }

  while ((entry = readdir(dir)) != NULL) {
    id = atoi(entry- d_name);
    if (id   0) {
      sprintf(filename, "/proc/%d/cmdline", id);
      file = fopen(filename, "r");

      if (file) {
        fgets(cmdline, sizeof(cmdline), file);
        fclose(file);

        if (strcmp(pack_name, cmdline) == 0) {
          pid = id;
          break;
        }
      }
    }
  }
  closedir(dir);
  return pid;
}

//打开文件句柄
int open_proc_mem(int pid) {

  if (pid <= 0)
    return -1;

  char mempath[64] = {0};
  int handle = -1;
  sprintf(mempath, "/proc/%d/mem", pid);

  handle = open(mempath, O_RDWR, O_SYNC);

  return handle;
}

//读内存
void pread64_mem(int fd, void *buff, int size, long *addr) {
  if (fd <= 0 || buff == NULL || size <= 0 || addr == NULL)
    return;
  pread64(fd, buff, size, (unsigned long) addr);
}

//写内存
void pwrite64_mem(int fd, const void *buff, int size, long *addr) {
  if (fd <= 0 || buff == NULL || size <= 0 || addr == NULL)
    return;
  pwrite64(fd, buff, size, (unsigned long) addr);
}

extern "C"
jint Java_com_gs_jc_JNI_searchMem(JNIEnv *env, jobject thiz) {
  char *game = "com.tencent.tmgp.sgame"; //包名

  int pid = getPID(game);		//获取进程PID
  fd = open_proc_mem(pid);	//打开进程内存

  //long base = 0;
  long buf[1] = {666};				//需要修改内存的值
  long *addr = (long *) 0x12C0085C;	//内存地址:0x12C0085C
  pwrite64_mem(fd, &buf[0], 4, addr);	//写入内存数据
  //pread64_mem(fd, &base, 4, addr);

  return pid;
}

char *game = “com.tencent.tmgp.sgame”; //包名
long *addr = (long *) 0x12C0085C;//内存地址