fs-lotus

Sugar to open and close a file descriptor.

usage

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). 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 with your error (if any).

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

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 do:

npm install fs-lotus

license

MIT © Vincent Weevers