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'use strict'
const BB = require('bluebird')
const contentPath = require('./content/path')
const crypto = require('crypto')
const fixOwner = require('./util/fix-owner')
const fs = require('graceful-fs')
const hashToSegments = require('./util/hash-to-segments')
const ms = require('mississippi')
const path = require('path')
const ssri = require('ssri')
const indexV = require('../package.json')['cache-version'].index
const appendFileAsync = BB.promisify(fs.appendFile)
const readFileAsync = BB.promisify(fs.readFile)
const readdirAsync = BB.promisify(fs.readdir)
const concat = ms.concat
const from = ms.from
module.exports.NotFoundError = class NotFoundError extends Error {
constructor (cache, key) {
super('content not found')
this.code = 'ENOENT'
this.cache = cache
this.key = key
}
}
module.exports.insert = insert
function insert (cache, key, integrity, opts) {
opts = opts || {}
const bucket = bucketPath(cache, key)
const entry = {
key,
integrity: integrity && ssri.stringify(integrity),
time: Date.now(),
size: opts.size,
metadata: opts.metadata
}
return fixOwner.mkdirfix(
path.dirname(bucket), opts.uid, opts.gid
).then(() => {
const stringified = JSON.stringify(entry)
// NOTE - Cleverness ahoy!
//
// This works because it's tremendously unlikely for an entry to corrupt
// another while still preserving the string length of the JSON in
// question. So, we just slap the length in there and verify it on read.
//
// Thanks to @isaacs for the whiteboarding session that ended up with this.
return appendFileAsync(
bucket, `\n${hashEntry(stringified)}\t${stringified}`
)
}).then(
() => fixOwner.chownr(bucket, opts.uid, opts.gid)
).catch({code: 'ENOENT'}, () => {
// There's a class of race conditions that happen when things get deleted
// during fixOwner, or between the two mkdirfix/chownr calls.
//
// It's perfectly fine to just not bother in those cases and lie
// that the index entry was written. Because it's a cache.
}).then(() => {
return formatEntry(cache, entry)
})
}
module.exports.find = find
function find (cache, key) {
const bucket = bucketPath(cache, key)
return bucketEntries(cache, bucket).then(entries => {
return entries.reduce((latest, next) => {
if (next && next.key === key) {
return formatEntry(cache, next)
} else {
return latest
}
}, null)
}).catch(err => {
if (err.code === 'ENOENT') {
return null
} else {
throw err
}
})
}
module.exports.delete = del
function del (cache, key, opts) {
return insert(cache, key, null, opts)
}
module.exports.lsStream = lsStream
function lsStream (cache) {
const indexDir = bucketDir(cache)
const stream = from.obj()
// "/cachename/*"
readdirOrEmpty(indexDir).map(bucket => {
const bucketPath = path.join(indexDir, bucket)
// "/cachename/<bucket 0xFF>/*"
return readdirOrEmpty(bucketPath).map(subbucket => {
const subbucketPath = path.join(bucketPath, subbucket)
// "/cachename/<bucket 0xFF>/<bucket 0xFF>/*"
return readdirOrEmpty(subbucketPath).map(entry => {
const getKeyToEntry = bucketEntries(
cache,
path.join(subbucketPath, entry)
).reduce((acc, entry) => {
acc.set(entry.key, entry)
return acc
}, new Map())
return getKeyToEntry.then(reduced => {
return Array.from(reduced.values()).map(
entry => stream.push(formatEntry(cache, entry))
)
}).catch({code: 'ENOENT'}, nop)
})
})
}).then(() => {
stream.push(null)
}, err => {
stream.emit('error', err)
})
return stream
}
module.exports.ls = ls
function ls (cache) {
return BB.fromNode(cb => {
lsStream(cache).on('error', cb).pipe(concat(entries => {
cb(null, entries.reduce((acc, xs) => {
acc[xs.key] = xs
return acc
}, {}))
}))
})
}
function bucketEntries (cache, bucket, filter) {
return readFileAsync(
bucket, 'utf8'
).then(data => {
let entries = []
data.split('\n').forEach(entry => {
if (!entry) { return }
const pieces = entry.split('\t')
if (!pieces[1] || hashEntry(pieces[1]) !== pieces[0]) {
// Hash is no good! Corruption or malice? Doesn't matter!
// EJECT EJECT
return
}
let obj
try {
obj = JSON.parse(pieces[1])
} catch (e) {
// Entry is corrupted!
return
}
if (obj) {
entries.push(obj)
}
})
return entries
})
}
module.exports._bucketDir = bucketDir
function bucketDir (cache) {
return path.join(cache, `index-v${indexV}`)
}
module.exports._bucketPath = bucketPath
function bucketPath (cache, key) {
const hashed = hashKey(key)
return path.join.apply(path, [bucketDir(cache)].concat(
hashToSegments(hashed)
))
}
module.exports._hashKey = hashKey
function hashKey (key) {
return hash(key, 'sha256')
}
module.exports._hashEntry = hashEntry
function hashEntry (str) {
return hash(str, 'sha1')
}
function hash (str, digest) {
return crypto
.createHash(digest)
.update(str)
.digest('hex')
}
function formatEntry (cache, entry) {
// Treat null digests as deletions. They'll shadow any previous entries.
if (!entry.integrity) { return null }
return {
key: entry.key,
integrity: entry.integrity,
path: contentPath(cache, entry.integrity),
size: entry.size,
time: entry.time,
metadata: entry.metadata
}
}
function readdirOrEmpty (dir) {
return readdirAsync(dir).catch({code: 'ENOENT'}, () => [])
}
function nop () {
}
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