fix: put infer-owner back in (#12)

@npmcli/exec is not out or ready and we need to get the cli updated to
use this again

lib/index.js

@@ -1,4 +1,5 @@
 const { spawn } = require('child_process')
+const inferOwner = require('infer-owner')
 
 const isPipe = (stdio = 'pipe', fd) =>
   stdio === 'pipe' || stdio === null ? true
@@ -8,9 +9,13 @@ const isPipe = (stdio = 'pipe', fd) =>
 // 'extra' object is for decorating the error a bit more
 const promiseSpawn = (cmd, args, opts = {}, extra = {}) => {
   const cwd = opts.cwd || process.cwd()
+  const isRoot = process.getuid && process.getuid() === 0
+  const { uid, gid } = isRoot ? inferOwner.sync(cwd) : {}
   return promiseSpawnUid(cmd, args, {
     ...opts,
     cwd,
+    uid,
+    gid,
   }, extra)
 }
 

package.json

@@ -41,5 +41,8 @@
   "templateOSS": {
     "//@npmcli/template-oss": "This file is partially managed by @npmcli/template-oss. Edits may be overwritten.",
     "version": "3.2.2"
+  },
+  "dependencies": {
+    "infer-owner": "^1.0.4"
   }
 }

test/promise-spawn.js

@@ -1,6 +1,7 @@
 const t = require('tap')
 const Minipass = require('minipass')
 const EE = require('events')
+const fs = require('fs')
 
 const isPipe = (stdio = 'pipe', fd) =>
   stdio === 'pipe' || stdio === null ? true
@@ -214,3 +215,33 @@ t.test('expose process', t => {
   t.end()
   setTimeout(() => p.process.exit(0))
 })
+
+t.test('infer ownership', t => {
+  const { lstatSync } = fs
+  t.teardown(() => fs.lstatSync = lstatSync)
+  fs.lstatSync = (path) => ({ uid: 420, gid: 69 })
+  const getuid = process.getuid
+  t.teardown(() => process.getuid = getuid)
+
+  t.test('as non-root, do not change uid/gid, regardless of arguments', t => {
+    process.getuid = () => 1234
+    return t.resolveMatch(promiseSpawn('whoami', [], { uid: 4321, gid: 9876 }), {
+      code: 0,
+      signal: null,
+      stdout: Buffer.from('UID undefined\nGID undefined\n'),
+      stderr: Buffer.alloc(0),
+    })
+  })
+
+  t.test('as root, change uid/gid to folder, regardless of arguments', t => {
+    process.getuid = () => 0
+    return t.resolveMatch(promiseSpawn('whoami', [], { uid: 4321, gid: 9876 }), {
+      code: 0,
+      signal: null,
+      stdout: Buffer.from('UID 420\nGID 69\n'),
+      stderr: Buffer.alloc(0),
+    })
+  })
+
+  t.end()
+})