win_ioctl

win_ioctl
==========

Node.js add-on to allow calls of DeviceIoControl() on Windows machines

Installation
------------

Install with npm:

`` bash
$ npm install win_ioctl
`

API
--------



$3


Parameters
- fd: Integer file descriptor, must be open.
- code: Integer Device specific control code.
- input optional: Buffer Input data to send to device
- outBufSize optional: Integer Size of output buffer to allocate
- cb optional: Function Callback to be called after operation finish
Signature is function (err, data) where err is instance of Error and data is Buffer

Returns: Buffer Allocated buffer of outBufSize size with data returned by device or undefined if cb is passed

Throws: Throws if cb is unset

Examples
--------

Get compression status of file
`
const comp_names =
{
0: 'COMPRESSION_FORMAT_NONE',
1: 'COMPRESSION_FORMAT_DEFAULT',
2: 'COMPRESSION_FORMAT_LZNT1',
};

let comp = win_ioctl(fd, FSCTL_GET_COMPRESSION, undefined, 2);
console.log('Compression: ' + comp_names[comp.readUInt16LE(0)]);
`

Async variant:
`
const comp_names =
{
0: 'COMPRESSION_FORMAT_NONE',
1: 'COMPRESSION_FORMAT_DEFAULT',
2: 'COMPRESSION_FORMAT_LZNT1',
};

win_ioctl(fd, FSCTL_GET_COMPRESSION, undefined, 2, (err, d) =>
console.log(err ? err : 'Compression: ' + comp_names[d.readUInt16LE(0)]));
`

Read variable-length data in case of ERR_MORE_DATA driver return:
`
win_ioctl(fd, FSCTL_FILESYSTEM_GET_STATISTICS, undefined, SIZE_OF_FILESYSTEM_STATISTICS, (err, data) =>
{
if (err)
{
if (err.code == 'ERANGE' && data)
{
let structSize = data.readUInt32LE(4), fullSize = os.cpus().length * structSize;
let fullData = win_ioctl(fd, FSCTL_FILESYSTEM_GET_STATISTICS, undefined, fullSize);
console.log('File has been read '+fullData.readUInt32LE(8)+' times');
} else
console.log('Error: '+err.message);
} else
console.log('Error: unexpected success of first request with small buffer!');
});
``