fix(write): wrap stuff in promises to improve errors

lib/content/write.js

@@ -6,11 +6,11 @@ const contentPath = require('./path')
 const fixOwner = require('../util/fix-owner')
 const fs = require('graceful-fs')
 const moveFile = require('../util/move-file')
+const PassThrough = require('stream').PassThrough
 const path = require('path')
-const pipe = require('mississippi').pipe
+const pipe = BB.promisify(require('mississippi').pipe)
 const rimraf = BB.promisify(require('rimraf'))
 const ssri = require('ssri')
-const through = require('mississippi').through
 const to = require('mississippi').to
 const uniqueFilename = require('unique-filename')
 
@@ -43,7 +43,7 @@ function write (cache, data, opts) {
 module.exports.stream = writeStream
 function writeStream (cache, opts) {
   opts = opts || {}
-  const inputStream = through()
+  const inputStream = new PassThrough()
   let inputErr = false
   function errCheck () {
     if (inputErr) { throw inputErr }
@@ -90,34 +90,23 @@ function handleContent (inputStream, cache, opts, errCheck) {
 }
 
 function pipeToTmp (inputStream, cache, tmpTarget, opts, errCheck) {
-  let sri
-  const hashStream = ssri.integrityStream({
-    integrity: opts.integrity,
-    algorithms: opts.algorithms,
-    size: opts.size
-  }).on('integrity', s => {
-    sri = s
-  })
-
-  let outStream = new BB((resolve, reject) => {
-    errCheck()
-    resolve(fs.createWriteStream(tmpTarget, {
+  return BB.resolve().then(() => {
+    let sri
+    const hashStream = ssri.integrityStream({
+      integrity: opts.integrity,
+      algorithms: opts.algorithms,
+      size: opts.size
+    }).on('integrity', s => {
+      sri = s
+    })
+    const outStream = fs.createWriteStream(tmpTarget, {
       flags: 'wx'
-    }))
-  })
-  return BB.using(outStream, outStream => {
+    })
     errCheck()
-    return new BB((resolve, reject) => {
-      errCheck()
-      inputStream.on('error', reject)
-      pipe(inputStream, hashStream, outStream, err => {
-        errCheck()
-        if (err) {
-          rimraf(tmpTarget).then(() => reject(err), reject)
-        } else {
-          resolve(sri)
-        }
-      })
+    return pipe(inputStream, hashStream, outStream).then(() => {
+      return sri
+    }, err => {
+      return rimraf(tmpTarget).then(() => { throw err })
     })
   })
 }