1
const file_path = path.resolve(output_f, patched_url.query.id + ".mp4")
2
if (!fs.existsSync(file_path)) {
3
    res.setHeader('Content-Type', 'text/html; charset=utf-8');
4
    res.end(`无文件! 可能是服务器自动删除 请重新上传下载`)
5
    return;
6
}
7

8
//跳过一些代码
9

10
const fs_stream = fs.createReadStream(file_path)
11
fs_stream.pipe(res)

1
//正常用法:
2
const a = "filename.txt" //外来可变变量
3
const target_path = path.resolve("/home/username/server/target_f/", a)
4
//target_path为"/home/username/server/target_f/filename.txt"
5

6
//被滥用:
7
const a = "../../filename.txt" //外来可变变量
8
const target_path = path.resolve("/home/username/server/target_f/", a)
9
//target_path为"/home/username/server/target_f/../../filename.txt"
10
//等效为/home/username/filename.txt