node-ffi

Question

我在 C 库中有 API，如下所示

EXPORT void test(char *a) {
    // Do something to change value of "a"
}

我想用 node-ffi 和 ref 将字符串指针传递给那个 API。我尝试了很多方法但没有成功。其他人可以帮我解决吗？

Answer 1

你打算如何防止缓冲区溢出？大多数输出字符串的函数还采用一个参数来指定已为该字符串分配的最大长度。这个问题没有解决，以下对我有用：

//use ffi and ref to interface with a c style dll
var ffi = require('ffi');
var ref = require('ref');

//load the dll. The dll is located in the current folder and named customlib.dll
var customlibProp = ffi.Library('customlib', {
    'myfunction': [ 'void', [ 'char *' ] ]
});

var maxStringLength = 200;
var theStringBuffer = new Buffer(maxStringLength);
theStringBuffer.fill(0); //if you want to initially clear the buffer
theStringBuffer.write("Intitial value", 0, "utf-8"); //if you want to give it an initial value

//call the function
customlibProp.myfunction(theStringBuffer);

//retrieve and convert the result back to a javascript string
var theString = theStringBuffer.toString('utf-8');
var terminatingNullPos = theString.indexOf('\u0000');
if (terminatingNullPos >= 0) {theString = theString.substr(0, terminatingNullPos);}
console.log("The string: ",theString);

我也不肯定你的 c 函数有正确的声明。我正在连接的函数有一个签名，如下所示： void (__stdcall *myfunction)(char *outputString); 也许 EXPORT 会解决同样的问题，我只是最近没有做过任何 c 编程来记住。

node-ffi - 将字符串指针传递给 C 库

node-ffi - Passing string pointer to C library

node.js

ref