overleaf/services/track-changes/app/js/ZipManager.js

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const logger = require('logger-sharelatex')
const UpdatesManager = require('./UpdatesManager')
const DiffGenerator = require('./DiffGenerator')
const DocumentUpdaterManager = require('./DocumentUpdaterManager')
const DocstoreManager = require('./DocstoreManager')
const PackManager = require('./PackManager')
const yazl = require('yazl')
const util = require('util')
const stream = require('stream')
const fs = require('fs')
const os = require('os')
const Path = require('path')
const streamPipeline = util.promisify(stream.pipeline)
// look in docstore or docupdater for the latest version of the document
async function getLatestContent(projectId, docId, lastUpdateVersion) {
const [docstoreContent, docstoreVersion] =
await DocstoreManager.promises.peekDocument(projectId, docId)
// if docstore is out of date, check for a newer version in docupdater
// and return that instead
if (docstoreVersion <= lastUpdateVersion) {
const [docupdaterContent, docupdaterVersion] =
await DocumentUpdaterManager.promises.peekDocument(projectId, docId)
if (docupdaterVersion > docstoreVersion) {
return [docupdaterContent, docupdaterVersion]
}
}
return [docstoreContent, docstoreVersion]
}
async function rewindDoc(projectId, docId, zipfile) {
logger.log({ projectId, docId }, 'rewinding document')
// Prepare to rewind content
const docIterator = await PackManager.promises.makeDocIterator(docId)
const getUpdate = util.promisify(docIterator.next).bind(docIterator)
const lastUpdate = await getUpdate()
if (!lastUpdate) {
return null
}
const lastUpdateVersion = lastUpdate.v
const [latestContent, version] = await getLatestContent(
projectId,
docId,
lastUpdateVersion
)
const id = docId.toString()
const contentEndPath = `${id}/content/end/${version}`
zipfile.addBuffer(Buffer.from(latestContent), contentEndPath)
const metadata = {
id,
version,
content: {
end: {
path: contentEndPath,
version,
},
},
updates: [],
}
let content = latestContent
let v = version
let update = lastUpdate
while (update) {
const updatePath = `${id}/updates/${update.v}`
zipfile.addBuffer(Buffer.from(JSON.stringify(update)), updatePath, {
mtime: new Date(update.meta.start_ts),
})
try {
content = DiffGenerator.rewindUpdate(content, update)
v = update.v
} catch (e) {
e.attempted_update = update // keep a record of the attempted update
logger.error({ projectId, docId, err: e }, 'rewind error')
break // stop attempting to rewind on error
}
metadata.updates.push({
path: updatePath,
version: update.v,
ts: update.meta.start_ts,
doc_length: content.length,
})
update = await getUpdate()
}
const contentStartPath = `${id}/content/start/${v}`
zipfile.addBuffer(Buffer.from(content), contentStartPath)
metadata.content.start = {
path: contentStartPath,
version: v,
}
return metadata
}
async function generateZip(projectId, zipfile) {
await UpdatesManager.promises.processUncompressedUpdatesForProject(projectId)
const docIds = await PackManager.promises.findAllDocsInProject(projectId)
const manifest = { projectId, docs: [] }
for (const docId of docIds) {
const doc = await rewindDoc(projectId, docId, zipfile)
if (doc) {
manifest.docs.push(doc)
}
}
zipfile.addBuffer(
Buffer.from(JSON.stringify(manifest, null, 2)),
'manifest.json'
)
zipfile.end()
}
async function exportProject(projectId, zipPath) {
const zipfile = new yazl.ZipFile()
const pipeline = streamPipeline(
zipfile.outputStream,
fs.createWriteStream(zipPath)
)
await generateZip(projectId, zipfile)
await pipeline
}
/**
* Create a temporary directory for use with exportProject()
*/
async function makeTempDirectory() {
const tmpdir = await fs.promises.mkdtemp(
(await fs.promises.realpath(os.tmpdir())) + Path.sep
)
return tmpdir
}
/**
* Clean up a temporary directory made with makeTempDirectory()
*/
function cleanupTempDirectory(tmpdir) {
fs.promises.rmdir(tmpdir, { recursive: true }).catch(err => {
logger.warn({ tmpdir }, 'Failed to clean up temp directory')
})
}
module.exports = {
exportProject: util.callbackify(exportProject),
makeTempDirectory: util.callbackify(makeTempDirectory),
cleanupTempDirectory,
}