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