Native file system extensions for advanced file operations. 

Native file system extensions for advanced file operations

mafintosh

kasperisager

fs-native-extensions

const binding = require('node-gyp-build')(__dirname)

  if (errno < 0) this.reject(toError(errno))

exports.tryLock = function tryLock (fd, offset = 0, length = 0, opts = {}) {

  const errno = binding.fs_ext_napi_try_lock(fd, offset, length, opts.shared ? 0 : 1)

    if (err.code === 'EAGAIN') return false

exports.waitForLock = function waitForLock (fd, offset = 0, length = 0, opts = {}) {

  const req = Buffer.alloc(binding.sizeof_fs_ext_napi_lock_t)

  const promise = new Promise((resolve, reject) => {

  const errno = binding.fs_ext_napi_wait_for_lock(req, fd, offset, length, opts.shared ? 0 : 1, ctx, onwork)

  if (errno < 0) return Promise.reject(toError(errno))

exports.tryDowngradeLock = function tryDowngradeLock (fd, offset = 0, length = 0) {

  const errno = binding.fs_ext_napi_try_downgrade_lock(fd, offset, length)

exports.waitForDowngradeLock = function downgradeLock (fd, offset = 0, length = 0) {

  const errno = binding.fs_ext_napi_wait_for_downgrade_lock(req, fd, offset, length, ctx, onwork)

exports.tryUpgradeLock = function tryUpgradeLock (fd, offset = 0, length = 0) {

  const errno = binding.fs_ext_napi_try_upgrade_lock(fd, offset, length)

  const [code, msg] = util.getSystemErrorMap().get(errno)

  const err = new Error(`${code}: ${msg}`)

    Error.captureStackTrace(err, toError)

  "description": "Native file system extensions for advanced file operations",

    "test": "standard && brittle test/*.mjs",

    "url": "git+https://github.com/holepunchto/fs-native-extensions.git"

  "author": "Kasper Isager Dalsgarð <kasper@funktionel.co>",

    "url": "https://github.com/holepunchto/fs-native-extensions/issues"

  "homepage": "https://github.com/holepunchto/fs-native-extensions#readme",

const { waitForLock, unlock } = require('fs-native-extensions')

const file = await open('file.txt', 'a+')

#### `const granted = tryLock(fd[, offset[, length]][, options])`

Request a lock on a file, returning `true` if the lock was granted or `false` if another file descriptor currently holds the lock.

To lock only a portion of the file, `offset` and `length` may be passed. A `length` of `0` will request a lock from `offset` to the end of the file.

On macOS, BSD locks are used and so only locks on the whole file are supported.

Note that the lock is only advisory and there is nothing stopping another process from accessing the file by simply ignoring the lock.

  // If `true`, request a shared lock, i.e. a read lock, on the file. By

  // default, an exclusive lock, i.e. a write lock, is requested.

  // Be aware that an exclusive lock can only be granted to files that are

#### `await waitForLock(fd[, offset[, length]][, options])`

Request a lock on a file, resolving when the lock is granted. If another file descriptor holds the lock, the lock will not be granted until the other file descriptor releases the lock.

#### `const granted = tryDowngradeLock(fd[, offset[, length]])`

Request a downgrade from an already held exclusive lock to a shared lock, returning `true` if the lock was granted or `false` if another process currently holds the lock. If `false` is returned, the exclusive lock is lost and must be requested again.

On Windows, the downgrade will happen atomically and be immediately granted.

#### `await waitForDowngradeLock(fd[, offset[, length]])`

Request a downgrade from an already held exclusive lock to a shared lock.

#### `const granted = tryUpgradeLock(fd[, offset[, length]])`

Request an upgrade from an already held shared lock to an exclusive lock, returning `true` if the lock was granted or `false` if another process currently holds the lock. If `false` is returned, the shared lock is lost and must be requested again.

#### `await waitForUpgradeLock(fd[, offset[, length]])`

Request an upgrade from an already held shared lock to an exclusive lock.

Create a hole in a file at `offset` for `length` bytes. On file systems that support sparse files, file blocks wholly covered by a hole will take up no physical space.

On Windows, the file must first be marked sparse using `sparse(fd)`. Otherwise, zeros will be explicitly written to the hole.

Mark a file as sparse. On Windows, this operation is required before holes can be punched in the file. On other systems, this operation has no effect.

Mark a file as sparse. On Windows, this operation is required before holes can be created in the file. On other systems, this operation has no effect.

Swap the paths `from` and `to`, making `from` assume the identity of `to` and `to` assume the identity of `from`.

On Windows, the swap is performed by first moving `to` to a temporary path, then moving `from` to `to`, and finally moving the temporary path to `from`.

On macOS and Linux, the swap is performed atomically.

		@@ -1,3 +0,3 @@
		const util = require('util')
		const binding = require('node-gyp-build')(__dirname)
		const errors = require('uv-errors')
		const binding = require('./binding')

		@@ -203,3 +203,3 @@ function onwork (errno) {
		function toError (errno) {
		const [code, msg] = util.getSystemErrorMap().get(errno)
		const [code, msg] = errors.get(errno)

		@@ -210,5 +210,7 @@ const err = new Error(`${code}: ${msg}`)

		Error.captureStackTrace(err, toError)
		if (Error.captureStackTrace) {
		Error.captureStackTrace(err, toError)
		}

		return err
		}

		{
		"name": "fs-native-extensions",
		"version": "1.1.0",
		"version": "1.2.0",
		"description": "Native file system extensions for advanced file operations",
		@@ -8,2 +8,3 @@ "main": "index.js",
		"index.js",
		"binding.js",
		"include",
		@@ -32,8 +33,9 @@ "src",
		"napi-macros": "^2.0.0",
		"node-gyp-build": "^4.2.3"
		"node-gyp-build": "^4.2.3",
		"uv-errors": "^1.0.1"
		},
		"devDependencies": {
		"brittle": "^2.3.1",
		"brittle": "^3.1.1",
		"minimist": "^1.2.6",
		"prebuildify": "^4.1.2",
		"prebuildify": "^5.0.1",
		"standard": "^17.0.0",
		@@ -40,0 +42,0 @@ "tempy": "^3.0.0"

		@@ -56,3 +56,3 @@ # fs-native-extensions

		Options are the same as `lock()`.
		Options are the same as `tryLock()`.

		@@ -91,3 +91,3 @@ #### `const granted = tryDowngradeLock(fd[, offset[, length]])`

		Mark a file as sparse. On Windows, this operation is required before holes can be punched in the file. On other systems, this operation has no effect.
		Mark a file as sparse. On Windows, this operation is required before holes can be created in the file. On other systems, this operation has no effect.

		@@ -94,0 +94,0 @@ #### `await swap(from, to)`

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