nodejs process.setgid、process.setuid 行为与 fs 模块

Question

目录：

drwxrwxr-x  2 alex alex 4096 Aug  3 12:03 ./
drwxr-xr-x 17 alex alex 4096 Aug  3 11:18 ../
-rwx------  1 root root   19 Aug  3 11:24 privilegedStuff*
-rwxrwx---  1 root root   28 Aug  3 12:10 privilegedStuff1*
-rwxrwxr-x  1 alex alex  830 Aug  3 12:12 test.js*

测试.js：

#!/usr/bin/env node
var fs = require('fs');
console.log('           user id: ', process.getuid());
console.log('          group id: ', process.getgid());
console.log(' user effective id: ', process.getegid());
console.log('group effective id: ', process.getegid());
console.log('\n switching user and group...\n');
process.setgid(1000);
process.setegid(1000);
process.setuid(1000);
process.seteuid(1000);
console.log('           user id: ', process.getuid());
console.log('          group id: ', process.getgid());
console.log(' user effective id: ', process.getegid());
console.log('group effective id: ', process.getegid());
console.log('\n output: \n');

console.log(fs.readFileSync('./privilegedStuff1', 'utf8'))

// this throws error as expected so I commented that
// console.log(fs.readFileSync('./privilegedStuff', 'utf8'))

特权材料1：

content of privilegedStuff1

结果：

alex@hp:/apps/test$ sudo ./test.js 
           user id:  0
          group id:  0
 user effective id:  0
group effective id:  0

 switching user and group...

           user id:  1000
          group id:  1000
 user effective id:  1000
group effective id:  1000

 output: 

content of privilegedStuff1

所以我不明白的是为什么 node 不会抛出错误，因为它很好地处理了 privilegedStuff 文件？ 我错过了什么？

alex@hp:/apps/test$ groups
alex adm cdrom sudo dip plugdev lpadmin sambashare
alex@hp:/apps/test$ cat privilegedStuff1
cat: privilegedStuff1: Permission denied
alex@hp:/apps/test$ sudo -s
root@hp:/apps/test# groups
root

Answer 1

在我的测试中，我没有这样的问题。

您能否输入以下命令并显示结果：

ls -l privilegedStuff1
id