fix: reserve paths case-insensitively

The path reservation system prevents multiple file entries clobbering one another while in flight, while allowing maximal parallelization in unpacking otherwise. However, on case-insensitive file systems, this can still introduce a race condition if the entries in the archive have different cases, as capital and lowercase entries will not be treated as reserving the same path. Normalize slashes and cases immediately when reserving paths, such that paths which differ only in case or slash repetition are treated as identical paths.

Author: isaacs

lib/path-reservations.js

@@ -8,6 +8,7 @@
 
 const assert = require('assert')
 const normPath = require('./normalize-windows-path.js')
+const { join } = require('path')
 
 module.exports = () => {
  // path => [function or Set]
@@ -19,10 +20,9 @@ module.exports = () => {
  const reservations = new Map()
 
  // return a set of parent dirs for a given path
- const { join } = require('path')
  const getDirs = path =>
- normPath(join(path)).split('/').slice(0, -1).reduce((set, path) =>
- set.length ? set.concat(normPath(join(set[set.length-1], path)))
+ path.split('/').slice(0, -1).reduce((set, path) =>
+ set.length ? set.concat(normPath(join(set[set.length - 1], path)))
  : [path], [])
 
  // functions currently running
@@ -99,6 +99,7 @@ module.exports = () => {
  }
 
  const reserve = (paths, fn) => {
+ paths = paths.map(p => normPath(join(p)).toLowerCase())
  const dirs = new Set(
  paths.map(path => getDirs(path)).reduce((a, b) => a.concat(b))
  )

test/path-reservations.js

@@ -49,7 +49,7 @@ t.test('basic race', t => {
  }
 
  t.ok(reserve(['a/b/c/d'], file), 'file starts right away')
- t.notOk(reserve(['a/b/c/d', 'a/b/e'], link), 'link waits')
+ t.notOk(reserve(['a/B/c////D', 'a/b/e'], link), 'link waits')
  t.notOk(reserve(['a/b/e/f'], dir), 'dir waits')
  t.notOk(reserve(['a/b'], dir2), 'dir2 waits')
  t.notOk(reserve(['a/b/x'], dir3), 'dir3 waits')