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97 lines
2.5 KiB
97 lines
2.5 KiB
10 years ago
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var fs = require('graceful-fs')
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var util = require('util')
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var crypto = require('crypto')
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function md5hex () {
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var hash = crypto.createHash('md5')
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for (var ii=0; ii<arguments.length; ++ii) {
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hash.update(''+arguments[ii])
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}
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return hash.digest('hex')
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}
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var invocations = 0;
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function getTmpname (filename) {
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return filename + "." + md5hex(__filename, process.pid, ++invocations)
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}
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module.exports = WriteStream
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util.inherits(WriteStream, fs.WriteStream)
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function WriteStream (path, options) {
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if (!options)
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options = {}
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if (!(this instanceof WriteStream))
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return new WriteStream(path, options)
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this.__atomicTarget = path
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this.__atomicChown = options.chown
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this.__atomicDidStuff = false
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this.__atomicTmp = getTmpname(path)
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fs.WriteStream.call(this, this.__atomicTmp, options)
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}
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function cleanup (er) {
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fs.unlink(this.__atomicTmp, function () {
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fs.WriteStream.prototype.emit.call(this, 'error', er)
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}.bind(this))
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}
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function cleanupSync (er) {
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try {
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fs.unlinkSync(this.__atomicTmp)
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} finally {
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return fs.WriteStream.prototype.emit.call(this, 'error', er)
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}
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}
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// When we *would* emit 'close' or 'finish', instead do our stuff
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WriteStream.prototype.emit = function (ev) {
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if (ev === 'error')
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return cleanupSync(this)
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if (ev !== 'close' && ev !== 'finish')
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return fs.WriteStream.prototype.emit.apply(this, arguments)
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// We handle emitting finish and close after the rename.
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if (ev === 'close' || ev === 'finish') {
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if (!this.__atomicDidStuff) {
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atomicDoStuff.call(this, function (er) {
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if (er)
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cleanup.call(this, er)
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}.bind(this))
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}
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}
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}
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function atomicDoStuff(cb) {
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if (this.__atomicDidStuff)
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throw new Error('Already did atomic move-into-place')
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this.__atomicDidStuff = true
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if (this.__atomicChown) {
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var uid = this.__atomicChown.uid
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var gid = this.__atomicChown.gid
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return fs.chown(this.__atomicTmp, uid, gid, function (er) {
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if (er) return cb(er)
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moveIntoPlace.call(this, cb)
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}.bind(this))
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} else {
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moveIntoPlace.call(this, cb)
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}
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}
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function moveIntoPlace (cb) {
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fs.rename(this.__atomicTmp, this.__atomicTarget, function (er) {
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cb(er)
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// emit finish, and then close on the next tick
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// This makes finish/close consistent across Node versions also.
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fs.WriteStream.prototype.emit.call(this, 'finish')
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process.nextTick(function() {
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fs.WriteStream.prototype.emit.call(this, 'close')
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}.bind(this))
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}.bind(this))
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}
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