fix: do not chown if not running as root

Fix: #3

Author: isaacs

lib/util/fix-owner.js

@@ -37,9 +37,15 @@ function fixOwner (cache, filepath) {
     // This platform doesn't need ownership fixing
     return BB.resolve()
   }
+
+  getSelf()
+  if (self.uid !== 0) {
+    // almost certainly can't chown anyway
+    return BB.resolve()
+  }
+
   return BB.resolve(inferOwner(cache)).then(owner => {
     const { uid, gid } = owner
-    getSelf()
 
     // No need to override if it's already what we used.
     if (self.uid === uid && self.gid === gid) {

test/content.write.chownr.js

@@ -1,12 +1,14 @@
 'use strict'
 
+const NEWUID = process.getuid() + 1
+const NEWGID = process.getgid() + 1
+
+process.getuid = () => 0
+
 const testDir = require('./util/test-dir')(__filename)
 const path = require('path')
 const CACHE = path.join(testDir, 'cache')
 const fs = require('fs')
-
-const NEWUID = process.getuid() + 1
-const NEWGID = process.getgid() + 1
 const stat = fs.lstat
 fs.lstat = (path, cb) => {
   stat(path, (er, st) => {