https://github.com/vweevers/fs-lotus

Sugar to open and close a file descriptor
https://github.com/vweevers/fs-lotus

Last synced: about 1 year ago
JSON representation

Sugar to open and close a file descriptor

• Host: GitHub
• URL: https://github.com/vweevers/fs-lotus
• Owner: vweevers
• License: mit
• Created: 2016-12-11T20:31:55.000Z (over 9 years ago)
• Default Branch: master
• Last Pushed: 2020-12-11T17:47:46.000Z (over 5 years ago)
• Last Synced: 2025-03-28T21:39:05.586Z (about 1 year ago)
• Language: JavaScript
• Homepage:
• Size: 3.91 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: readme.md
  • License: LICENSE

Awesome Lists containing this project

README

          
# fs-lotus

**Sugar to open and close a file descriptor.**

[![npm status](http://img.shields.io/npm/v/fs-lotus.svg?style=flat-square)](https://www.npmjs.org/package/fs-lotus) [![node](https://img.shields.io/node/v/fs-lotus.svg?style=flat-square)](https://www.npmjs.org/package/fs-lotus) [![Travis build status](https://img.shields.io/travis/vweevers/fs-lotus.svg?style=flat-square&label=travis)](http://travis-ci.org/vweevers/fs-lotus) [![AppVeyor build status](https://img.shields.io/appveyor/ci/vweevers/fs-lotus.svg?style=flat-square&label=appveyor)](https://ci.appveyor.com/project/vweevers/fs-lotus) [![Dependency status](https://img.shields.io/david/vweevers/fs-lotus.svg?style=flat-square)](https://david-dm.org/vweevers/fs-lotus)

## usage

```js

const open = require('fs-lotus')

    , fs = require('fs')

const readExactly = function (filename, pos, length, done) {

  open(filename, 'r', function (err, fd, close) {

    if (err) return done(err)

    fs.read(fd, Buffer(length), 0, length, pos, function (err, bytesRead, buf) {

      if (err) return close(done, err)

      if (bytesRead !== length) {

        return close(done, new Error('End of file'))

      }

      close(done, null, buf)

    })

  })

}

```

The `open` function has the same signature as [`fs.open(path, flags[, mode], callback)`](https://nodejs.org/api/fs.html#fs_fs_open_path_flags_mode_callback). Except that `callback` also receives a `close(callback, err, ...args)` function, which calls `fs.close` for you. An error from `fs.close` (if any) will be [combined](https://github.com/matthewmueller/combine-errors) with your error (if any).

This pattern ensures that our `readExactly` function doesn't leak fd's.

```js

readExactly('readme.md', 0, 10, function (err, buf) {

  console.log(buf.toString()) // '# fs-lotus'

})

readExactly('readme.md', 1e5, 10, function (err, buf) {

  console.log(err.toString()) // 'Error: End of file'

})

```

## install

With [npm](https://npmjs.org) do:

```

npm install fs-lotus

```

## license

[MIT](http://opensource.org/licenses/MIT) © Vincent Weevers