feat: infer ownership of created dirs and links

lib/chown.js

@@ -0,0 +1,24 @@
+'use strict'
+
+// A module for chowning things we just created, to preserve
+// ownership of new links and directories.
+
+const chownr = require('chownr')
+
+const selfOwner = {
+  uid: process.getuid && process.getuid(),
+  gid: process.getgid && process.getgid()
+}
+
+module.exports = (path, uid, gid, cb) => {
+  if (selfOwner.uid !== 0 ||
+      uid === undefined || gid === undefined ||
+      (selfOwner.uid === uid && selfOwner.gid === gid)) {
+    // don't need to, or can't chown anyway, so just leave it.
+    // this also handles platforms where process.getuid is undefined
+    return cb()
+  }
+  chownr(path, uid, gid, cb)
+}
+
+module.exports.selfOwner = selfOwner

lib/link.js

@@ -3,8 +3,10 @@
 const path = require('path')
 const fs = require('graceful-fs')
 const chain = require('slide').chain
-const mkdir = require('mkdirp')
+const mkdir = require('./mkdir.js')
 const rm = require('./rm.js')
+const inferOwner = require('infer-owner')
+const chown = require('./chown.js')
 
 exports = module.exports = {
   link: link,
@@ -53,14 +55,20 @@ function link (from, to, opts, cb) {
   var relativeTarget = path.relative(opts.base, absTarget)
   var target = opts.absolute ? absTarget : relativeTarget
 
-  chain(
-    [
-      [ensureFromIsNotSource, absTarget, to],
-      [fs, 'stat', absTarget],
-      [rm, to, opts],
-      [mkdir, path.dirname(to)],
-      [fs, 'symlink', target, to, 'junction']
-    ],
-    cb
-  )
+  const tasks = [
+    [ensureFromIsNotSource, absTarget, to],
+    [fs, 'stat', absTarget],
+    [rm, to, opts],
+    [mkdir, path.dirname(to)],
+    [fs, 'symlink', target, to, 'junction']
+  ]
+
+  if (chown.selfOwner !== 0) {
+    chain(tasks, cb)
+  } else {
+    inferOwner.then(owner => {
+      tasks.push([chown, to, owner.uid, owner.gid])
+      chain(tasks, cb)
+    })
+  }
 }

lib/mkdir.js

@@ -0,0 +1,22 @@
+'use strict'
+
+const mkdirp = require('mkdirp')
+const inferOwner = require('infer-owner')
+const chown = require('./chown.js')
+
+module.exports = (path, cb) => {
+  // don't bother chowning if we can't anyway
+  if (process.platform === 'win32' || chown.selfOwner.uid !== 0) {
+    return mkdirp(path, cb)
+  }
+
+  inferOwner(path).then(owner => {
+    mkdirp(path, (er, made) => {
+      if (er) {
+        cb(er, made)
+      } else {
+        chown(made || path, owner.uid, owner.gid, cb)
+      }
+    })
+  }, cb)
+}