如何在node-ffi中使用EnumProcesses

Question

我试着在node-ffi中使用EnumProcesses。我的代码如下：

import ffi from 'ffi'

export const psapi = ffi.Library('psapi', {
  EnumProcesses: ['bool', ['ulong', 'ulong', 'uint16*']]
})

export class Win32ProcessManager {
  public async getProcessList () {

    let lpidProcess = ref.alloc('ulong*')
    const cb = 1024
    const lpcbNeeded = ref.alloc('uint16*')

    const res = psapi.EnumProcesses(lpidProcess, cb, lpcbNeeded)

    const ulongSize = (ref as any).sizeof.ulong
    const totalBytesReturned = lpcbNeeded.readInt16LE()
    const processCount = totalBytesReturned / ulongSize
    console.log(`processCount: ${processCount}`)

    // ??? How to get the value from the lpidProcess?
    return lpidProcess
  }
}

我尝试使用ref.get，但遇到错误：

    let processId = ref.get(array, 0, ref.types.ulong)
    console.log(processId)
    const pointerSize = (ref as any).sizeof.pointer
    console.log(pointerSize)
    let processId2 = ref.get(array, (ref as any).sizeof.pointer, ref.types.ulong)
    console.log(processId2)

错误：

RangeError [ERR_BUFFER_OUT_OF_BOUNDS]: Attempt to write outside buffer bounds

谁知道如何使用node-ffi从dll中读取数组数据？

Answer 1

谢谢@DrakeWu-MSFT，我终于得到了我的代码工作，这是他们最终的样子：

import ffi from 'ffi';
import ref from 'ref';
import ArrayType from "ref-array";

export const psapi = ffi.Library('psapi', {
  EnumProcesses: ['bool', ['ulong*', 'ulong', 'uint16*']],
});

export class Win32ProcessManager {

  public getProcessIdList (): number[] {
    const processIdLength = 1024;
    const ulongSize = (ref as any).sizeof.ulong;
    const cb = processIdLength * ulongSize;
    let processIdArray = ArrayType('ulong', processIdLength);
    let lpidProcess = ref.alloc(processIdArray);
    const lpcbNeeded = ref.alloc('uint16*');

    const res = psapi.EnumProcesses(lpidProcess, cb, lpcbNeeded);

    if (res) {
      const totalBytesReturned = lpcbNeeded.readInt16LE();
      const processCount = totalBytesReturned / ulongSize;
  
      const processArray = (lpidProcess as any).deref();
      let resultProcessArray: number[] = [];
      for (let i = 0; i < processCount; i++) {
        resultProcessArray.push(processArray[i]);
      }
  
      return resultProcessArray;
    } else {
      console.error(`Get process list failed with result from EnumProcess: ${res}`);
      return [];
    }
  }
}

我很难从指针中获取数组数据，正如@DrakeWu-MSFT在评论中所说的那样，这是错误的，因为我没有为缓冲区分配足够的空间，没有数据可以写入其中。有了ref-array和指向数组的指针，它就像一个护身符一样工作。