sbot/app/lib/blobs.js

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var path = require('path')
var multicb = require('multicb')
var toPath = require('multiblob/util').toPath
var createHash = require('multiblob/util').createHash
var pull = require('pull-stream')
var toPull = require('stream-to-pull-stream')
var querystring = require('querystring')
var fs = require('fs')
// blob url parser
var re = /^blob:([a-z0-9\+\/=]+\.blake2s)\??(.*)$/i
var url_parse =
module.exports.url_parse = function (str) {
var parts = re.exec(str)
if (parts)
return { hash: parts[1], qs: querystring.parse(parts[2]) }
}
// blob url builder
var url_stringify =
module.exports.url_stringify = function (hash, qs) {
var url = 'blob:'+hash
if (qs && typeof qs == 'object')
url += '?' + querystring.stringify(qs)
return url
}
module.exports = function (blobs_dir, checkout_dir) {
return {
// behavior for the blob: protocol
protocol: function (request) {
var protocol = require('protocol') // have to require here, doing so before app:ready causes errors
// simple fetch
var parsed = url_parse(request.url)
if (request.method == 'GET' && parsed) {
return new protocol.RequestFileJob(toPath(blobs_dir, parsed.hash))
}
},
// copy file from blobs into given dir with nice name
checkout: function (url, cb) {
var parsed = url_parse(url)
if (!parsed)
return cb({ badUrl: true })
var filename = parsed.qs.name || parsed.qs.filename || parsed.hash
// check if we have the blob, at the same time find an available filename
var done = multicb()
fs.stat(toPath(blobs_dir, parsed.hash), done())
findCheckoutDst(filename, parsed.hash, done())
done(function (err, res) {
if (!res[0][1])
return cb({ notFound: true })
// do we need to copy?
var dst = res[1][1]
var nocopy = res[1][2]
if (nocopy)
return cb(null, dst)
// copy the file
var src = toPath(blobs_dir, parsed.hash)
var read = fs.createReadStream(src)
var write = fs.createWriteStream(dst)
read.on('error', done)
write.on('error', done)
write.on('close', done)
read.pipe(write)
function done (err) {
cb && cb(err, dst)
cb = null
}
})
}
}
// helper to create a filename in checkout_dir that isnt already in use
// - cb(err, filepath, nocopy) - if nocopy==true, no need to do the copy operation
function findCheckoutDst (filename, hash, cb) {
var n = 1
var parsed = path.parse(filename)
next()
function gen () {
var name = parsed.name
if (n !== 1) name += ' ('+n+')'
name += parsed.ext
n++
return path.join(checkout_dir, name)
}
function next () {
var dst = gen()
// exists?
fs.stat(dst, function (err, stat) {
if (!stat)
return cb(null, dst, false)
// yes, check its hash
var hasher = createHash()
pull(
toPull.source(fs.createReadStream(dst)),
hasher,
pull.onEnd(function () {
// if the hash matches, we're set
if (hasher.digest == hash)
return cb(null, dst, true)
// try next
next()
})
)
})
}
}
}