JavaScript调用C库

本文介绍通过ffi方式调用C动态库
系统：ubuntu16.04 64bit

一、环境安装

1. 安装js运行环境

   • V17.3.0 地址：https://nodejs.org/dist
   • wget https://nodejs.org/dist/v17.6.0/node-v17.6.0-linux-x64.tar.xz
   • 解压tar xvf node-v17.6.0-linux-x64.tar.xz
   • sudo mv node-v17.6.0-linux-x64 /usr/local/nodejs
   • 添加环境变量 vi ~/.bashrc (添加后重启终端窗口)

     export PATH=$PATH:/usr/local/nodejs/bin
     export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/nodejs/lib
     

2. 安装ffi相关

   • 设置源：npm config set registry https://registry.npmmirror.com （淘宝）
   • npm config set python /usr/bin/python3 (python>3.6.0)
   • npm install node-gyp
   • npm install ffi-napi
   • npm install ref-napi
   • npm install ref-array-napi
   • npm install ref-struct-napi

二、测试代码

1. c代码test.c–>编译出动态库libtest.so

   #include 
   typedef struct {
       int id;
       char* name;
       double height;
       int score[10];
       int score_size;
   }userStruct;
   typedef void (*callback)(int val);
   static char char_point[64] = "";
   int api_int(int a, int b) {
       return a + b;
   }
   
   double api_double(double a, double b) {
       return a + b;
   }
   
   char* api_char_point(char* a, char* b){
       memset(char_point, 0, sizeof(char_point));
       sprintf(char_point, "%s %s", a, b);
       return char_point;
   }
   
   int api_int_array(int* a, int size){
       int i = 0; 
       for(i = 0; i < size; i++){
           a[i] = i;
       }
       return 0;
   }
   
   int api_struct(userStruct user){
       int i = 0;
       char buf[128] = "";
       printf("C Print score_size:%d\n", user.score_size);
       for(i = 0; i < user.score_size; i++){
           printf("C Print i:%d, score:%d\n",i, user.score[i]);
           sprintf(buf, "%s %d", buf, user.score[i]);
       }
       printf("C Print id:%d name:%s height:%f socre:%s\n", user.id, user.name, user.height, buf);
       return 0;
   }
   void api_callback(callback cb){
       cb(1);
   }
   
   

2. js代码 test.js

   const ffi = require('ffi-napi');
   const ref = require('ref-napi');
   const refArray = require('ref-array-napi')
   const StructType = require('ref-struct-napi');
   const IntArray10 = refArray(ref.types.int, 10);
   const userStruct = StructType({
       id: 'int',
       name: 'string',
       height: 'double',
       score: IntArray10,
       score_size: 'int'
   });
   
   const rockeyInterface = {
       'api_int':['int', ['int', 'int']],
       'api_double':['double', ['double', 'double']],
       'api_char_point':['string', ['string', 'string']],
       'api_int_array':['int', ['pointer', 'int']],
       'api_struct':['int', [userStruct]],
       'api_callback':['void', ['pointer']]
   }
   
   let libtest = new ffi.Library('./libtest.so', rockeyInterface);
   //int test
   console.log("int result:", libtest.api_int(1, 2));
   //double test
   console.log("double Result:", libtest.api_double(1.1, 1.2));
   //char* test
   console.log("char* result:", libtest.api_char_point('hello', 'world'));
   //int array test
   let arraySize = 10;
   let arrayBuf = Buffer.alloc(arraySize* Int32Array.BYTES_PER_ELEMENT);
   console.log(typeof arrayBuf);
   console.log(arrayBuf.length);
   if(libtest.api_int_array(arrayBuf, arraySize) == 0){
       let arrayResult = new Int32Array(arrayBuf.buffer);
       console.log("int array result:", arrayResult);
   }
   //struct test
   let user = new userStruct();
   user.id = 101;
   user.name = 'hsl';
   user.height = 1.78;
   user.score_size = 10;
   user.score = new IntArray10();
   for(var i = 0; i < user.score_size; i++){
       user.score[i] = i+1;
   }
   let ret = libtest.api_struct(user);
   console.log("struct result:", ret);
   
   //callback test
   const callback = ffi.Callback('int', ['int'], function(value){
       console.log("callback result:", value);
   });
   libtest.api_callback(callback);
   

3. 运行：node test.js

附：

python3升级
	下载：wget https://www.python.org/ftp/python/3.7.9/Python-3.7.9.tgz
	tar xvf Python-3.7.9.tgz
	cd Python-3.7.9
	./configure
	make && sudo make install
	sudo rm /usr/bin/python3
	sudo ln -s /usr/local/bin/python3 /usr/bin/python3