* first action! (#1)

node_modules/tar/lib/extract.js

@@ -0,0 +1,112 @@
+'use strict'
+
+// tar -x
+const hlo = require('./high-level-opt.js')
+const Unpack = require('./unpack.js')
+const fs = require('fs')
+const fsm = require('fs-minipass')
+const path = require('path')
+
+const x = module.exports = (opt_, files, cb) => {
+  if (typeof opt_ === 'function')
+    cb = opt_, files = null, opt_ = {}
+  else if (Array.isArray(opt_))
+    files = opt_, opt_ = {}
+
+  if (typeof files === 'function')
+    cb = files, files = null
+
+  if (!files)
+    files = []
+  else
+    files = Array.from(files)
+
+  const opt = hlo(opt_)
+
+  if (opt.sync && typeof cb === 'function')
+    throw new TypeError('callback not supported for sync tar functions')
+
+  if (!opt.file && typeof cb === 'function')
+    throw new TypeError('callback only supported with file option')
+
+  if (files.length)
+    filesFilter(opt, files)
+
+  return opt.file && opt.sync ? extractFileSync(opt)
+    : opt.file ? extractFile(opt, cb)
+    : opt.sync ? extractSync(opt)
+    : extract(opt)
+}
+
+// construct a filter that limits the file entries listed
+// include child entries if a dir is included
+const filesFilter = (opt, files) => {
+  const map = new Map(files.map(f => [f.replace(/\/+$/, ''), true]))
+  const filter = opt.filter
+
+  const mapHas = (file, r) => {
+    const root = r || path.parse(file).root || '.'
+    const ret = file === root ? false
+      : map.has(file) ? map.get(file)
+      : mapHas(path.dirname(file), root)
+
+    map.set(file, ret)
+    return ret
+  }
+
+  opt.filter = filter
+    ? (file, entry) => filter(file, entry) && mapHas(file.replace(/\/+$/, ''))
+    : file => mapHas(file.replace(/\/+$/, ''))
+}
+
+const extractFileSync = opt => {
+  const u = new Unpack.Sync(opt)
+
+  const file = opt.file
+  let threw = true
+  let fd
+  const stat = fs.statSync(file)
+  // This trades a zero-byte read() syscall for a stat
+  // However, it will usually result in less memory allocation
+  const readSize = opt.maxReadSize || 16*1024*1024
+  const stream = new fsm.ReadStreamSync(file, {
+    readSize: readSize,
+    size: stat.size
+  })
+  stream.pipe(u)
+}
+
+const extractFile = (opt, cb) => {
+  const u = new Unpack(opt)
+  const readSize = opt.maxReadSize || 16*1024*1024
+
+  const file = opt.file
+  const p = new Promise((resolve, reject) => {
+    u.on('error', reject)
+    u.on('close', resolve)
+
+    // This trades a zero-byte read() syscall for a stat
+    // However, it will usually result in less memory allocation
+    fs.stat(file, (er, stat) => {
+      if (er)
+        reject(er)
+      else {
+        const stream = new fsm.ReadStream(file, {
+          readSize: readSize,
+          size: stat.size
+        })
+        stream.on('error', reject)
+        stream.pipe(u)
+      }
+    })
+  })
+  return cb ? p.then(cb, cb) : p
+}
+
+const extractSync = opt => {
+  return new Unpack.Sync(opt)
+}
+
+const extract = opt => {
+  return new Unpack(opt)
+}