* first action! (#1)

node_modules/fs-write-stream-atomic/index.js

@@ -0,0 +1,176 @@
+var fs = require('graceful-fs')
+var Writable = require('readable-stream').Writable
+var util = require('util')
+var MurmurHash3 = require('imurmurhash')
+var iferr = require('iferr')
+var crypto = require('crypto')
+
+function murmurhex () {
+  var hash = MurmurHash3('')
+  for (var ii = 0; ii < arguments.length; ++ii) {
+    hash.hash('' + arguments[ii])
+  }
+  return hash.result()
+}
+
+var invocations = 0
+function getTmpname (filename) {
+  return filename + '.' + murmurhex(__filename, process.pid, ++invocations)
+}
+
+var setImmediate = global.setImmediate || setTimeout
+
+module.exports = WriteStreamAtomic
+
+// Requirements:
+//   1. Write everything written to the stream to a temp file.
+//   2. If there are no errors:
+//      a. moves the temp file into its final destination
+//      b. emits `finish` & `closed` ONLY after the file is
+//         fully flushed and renamed.
+//   3. If there's an error, removes the temp file.
+
+util.inherits(WriteStreamAtomic, Writable)
+function WriteStreamAtomic (path, options) {
+  if (!(this instanceof WriteStreamAtomic)) {
+    return new WriteStreamAtomic(path, options)
+  }
+  Writable.call(this, options)
+
+  this.__isWin = options && options.hasOwnProperty('isWin') ? options.isWin : process.platform === 'win32'
+
+  this.__atomicTarget = path
+  this.__atomicTmp = getTmpname(path)
+
+  this.__atomicChown = options && options.chown
+
+  this.__atomicClosed = false
+
+  this.__atomicStream = fs.WriteStream(this.__atomicTmp, options)
+
+  this.__atomicStream.once('open', handleOpen(this))
+  this.__atomicStream.once('close', handleClose(this))
+  this.__atomicStream.once('error', handleError(this))
+}
+
+// We have to suppress default finish emitting, because ordinarily it
+// would happen as soon as `end` is called on us and all of the
+// data has been written to our target stream. So we suppress
+// finish from being emitted here, and only emit it after our
+// target stream is closed and we've moved everything around.
+WriteStreamAtomic.prototype.emit = function (event) {
+  if (event === 'finish') return this.__atomicStream.end()
+  return Writable.prototype.emit.apply(this, arguments)
+}
+
+WriteStreamAtomic.prototype._write = function (buffer, encoding, cb) {
+  var flushed = this.__atomicStream.write(buffer, encoding)
+  if (flushed) return cb()
+  this.__atomicStream.once('drain', cb)
+}
+
+function handleOpen (writeStream) {
+  return function (fd) {
+    writeStream.emit('open', fd)
+  }
+}
+
+function handleClose (writeStream) {
+  return function () {
+    if (writeStream.__atomicClosed) return
+    writeStream.__atomicClosed = true
+    if (writeStream.__atomicChown) {
+      var uid = writeStream.__atomicChown.uid
+      var gid = writeStream.__atomicChown.gid
+      return fs.chown(writeStream.__atomicTmp, uid, gid, iferr(cleanup, moveIntoPlace))
+    } else {
+      moveIntoPlace()
+    }
+  }
+
+  function moveIntoPlace () {
+    fs.rename(writeStream.__atomicTmp, writeStream.__atomicTarget, iferr(trapWindowsEPERM, end))
+  }
+
+  function trapWindowsEPERM (err) {
+    if (writeStream.__isWin &&
+        err.syscall && err.syscall === 'rename' &&
+        err.code && err.code === 'EPERM'
+    ) {
+      checkFileHashes(err)
+    } else {
+      cleanup(err)
+    }
+  }
+
+  function checkFileHashes (eperm) {
+    var inprocess = 2
+    var tmpFileHash = crypto.createHash('sha512')
+    var targetFileHash = crypto.createHash('sha512')
+
+    fs.createReadStream(writeStream.__atomicTmp)
+      .on('data', function (data, enc) { tmpFileHash.update(data, enc) })
+      .on('error', fileHashError)
+      .on('end', fileHashComplete)
+    fs.createReadStream(writeStream.__atomicTarget)
+      .on('data', function (data, enc) { targetFileHash.update(data, enc) })
+      .on('error', fileHashError)
+      .on('end', fileHashComplete)
+
+    function fileHashError () {
+      if (inprocess === 0) return
+      inprocess = 0
+      cleanup(eperm)
+    }
+
+    function fileHashComplete () {
+      if (inprocess === 0) return
+      if (--inprocess) return
+      if (tmpFileHash.digest('hex') === targetFileHash.digest('hex')) {
+        return cleanup()
+      } else {
+        return cleanup(eperm)
+      }
+    }
+  }
+
+  function cleanup (err) {
+    fs.unlink(writeStream.__atomicTmp, function () {
+      if (err) {
+        writeStream.emit('error', err)
+        writeStream.emit('close')
+      } else {
+        end()
+      }
+    })
+  }
+
+  function end () {
+    // We have to use our parent class directly because we suppress `finish`
+    // events fired via our own emit method.
+    Writable.prototype.emit.call(writeStream, 'finish')
+
+    // Delay the close to provide the same temporal separation a physical
+    // file operation would have– that is, the close event is emitted only
+    // after the async close operation completes.
+    setImmediate(function () {
+      writeStream.emit('close')
+    })
+  }
+}
+
+function handleError (writeStream) {
+  return function (er) {
+    cleanupSync()
+    writeStream.emit('error', er)
+    writeStream.__atomicClosed = true
+    writeStream.emit('close')
+  }
+  function cleanupSync () {
+    try {
+      fs.unlinkSync(writeStream.__atomicTmp)
+    } finally {
+      return
+    }
+  }
+}