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module.exports = FSStorage
var fs = require('fs')
var inherits = require('inherits')
var mkdirp = require('mkdirp')
var os = require('os')
var path = require('path')
var raf = require('random-access-file')
var rimraf = require('rimraf')
var Storage = require('./storage')
var thunky = require('thunky')
var TMP = path.join(fs.existsSync('/tmp') ? '/tmp' : os.tmpDir(), 'webtorrent')
inherits(FSStorage, Storage)
/**
* fs-backed Storage for a torrent download.
*
* @param {Object} parsedTorrent
* @param {Object} opts
*/
function FSStorage (parsedTorrent, opts) {
var self = this
self.tmp = opts.tmp || TMP
self.path = opts.path || path.join(self.tmp, parsedTorrent.infoHash)
self.piecesMap = []
self.nonExistentError = new Error('Cannot read from non-existent file')
opts.nobuffer = true
Storage.call(self, parsedTorrent, opts)
self.files.forEach(function (file) {
var fileStart = file.offset
var fileEnd = fileStart + file.length
var pieceLength = file.pieceLength
var filePath = path.join(self.path, file.path)
var openWrite = thunky(function (cb) {
var fileDir = path.dirname(filePath)
mkdirp(fileDir, function (err) {
if (err) return cb(err)
if (self.closed) return cb(new Error('Storage closed'))
var fd = raf(filePath)
file.fd = fd
cb(null, fd)
})
})
var openRead = thunky(function (cb) {
// TODO: no need for fs.exists call, just try opening and handle error.
// fs.exists then open creates opportunity for race condition.
fs.exists(filePath, function (exists) {
if (exists) return openWrite(cb)
cb(self.nonExistentError)
})
})
file.pieces.forEach(function (piece) {
var index = piece.index
var pieceStart = index * pieceLength
var pieceEnd = pieceStart + piece.length
var from = (fileStart < pieceStart) ? 0 : fileStart - pieceStart
var to = (fileEnd > pieceEnd) ? pieceLength : fileEnd - pieceStart
var offset = (fileStart > pieceStart) ? 0 : pieceStart - fileStart
if (!self.piecesMap[index]) self.piecesMap[index] = []
self.piecesMap[index].push({
from: from,
to: to,
offset: offset,
openWrite: openWrite,
openRead: openRead
})
})
})
}
FSStorage.prototype.readBlock = function (index, offset, length, cb) {
var self = this
if (!cb) return console.error('FSStorage.readBlock requires a callback')
var piece = self.pieces[index]
if (!piece) return cb(new Error('invalid piece index ' + index))
if (piece.verified && piece.buffer) {
// piece is verified and cached in memory, so read directly from its buffer
// instead of reading from the filesystem.
return piece.readBlock(offset, length, cb)
}
var rangeFrom = offset
var rangeTo = rangeFrom + length
var targets = self.piecesMap[index].filter(function (target) {
return (target.to > rangeFrom && target.from < rangeTo)
})
if (!targets.length) return cb(new Error('no file matching the requested range?'))
var buffers = []
var end = targets.length
var i = 0
function readFromNextFile (err, buffer) {
if (err) return cb(err)
if (buffer) buffers.push(buffer)
if (i >= end) return cb(null, Buffer.concat(buffers))
var target = targets[i++]
var from = target.from
var to = target.to
var offset = target.offset
if (to > rangeTo) to = rangeTo
if (from < rangeFrom) {
offset += rangeFrom - from
from = rangeFrom
}
target.openRead(function (err, file) {
if (err) {
return err === self.nonExistentError
? readFromNextFile(null, new Buffer(0))
: cb(err)
}
file.read(offset, to - from, readFromNextFile)
})
}
readFromNextFile()
}
// flush pieces to file once they're done and verified
FSStorage.prototype._onPieceDone = function (piece) {
var self = this
var targets = self.piecesMap[piece.index]
var end = targets.length
var i = 0
function cb () {
Storage.prototype._onPieceDone.call(self, piece)
}
if (!piece.buffer || self.readonly) return cb()
var writeToNextFile = function (err) {
if (err) return self.emit('error', err)
if (i >= end) {
return cb()
}
var target = targets[i++]
target.openWrite(function (err, file) {
if (self.closed) return
if (err) return self.emit('error', err)
file.write(target.offset, piece.buffer.slice(target.from, target.to), writeToNextFile)
})
}
writeToNextFile()
}
/**
* Removes and cleans up any backing store for this storage.
*/
FSStorage.prototype.remove = function (cb) {
var self = this
if (!cb) cb = function () {}
self.close(function (err) {
if (err) return cb(err)
var root = self.files[0].path.split(path.sep)[0]
rimraf(path.join(self.path, root), cb)
})
}
/**
* Closes the backing store for this storage.
*/
FSStorage.prototype.close = function (cb) {
var self = this
if (!cb) cb = function () {}
if (self.closed) return cb()
Storage.prototype.close.call(self, function (err) {
if (err) return cb(err)
var i = 0
function loop (err) {
if (i >= self.files.length) return cb()
if (err) return cb(err)
var next = self.files[i++]
if (!next || !next.fd) return process.nextTick(loop)
next.fd.close(loop)
}
process.nextTick(loop)
})
}
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