In a Java thread running as an administrator, how can we apply Unix privileges to login?

Question

We have a Java program that runs as root on Unix, so it can read, for example, the contents of folders /home/user1and /home/user2. However, if the Unix user "user1" is registered in our application, he should not have access to the data "/ home / user2". We would like to directly use Unix rights and not recreate all permissions in our application! So can we ...

• try to change the UID of our program depending on the user registered in? It sounds complicated, and each file is accessed in different streams, so the UID will be different on each thread of our program ...
• use JNI to read permissions " /home/user2" ... And then determine if user1 has sufficient permissions to " /home/user2"? (as?).

Answer 1

Use SecurityManager!

• Paste the current unix user id into ThreadLocal
• Create your own SecurityManager that checks unix user rights on checkRead () and checkWrite ()
• System.setSecurityManager (new MySecurityManager ())
• Enjoy

Update

Of course, there is no standard library for reading unix file permissions. This is not WORA.

: http://jan.newmarch.name/java/posix/ JNI, JNI, .:) , .

Stat : http://jan.newmarch.name/java/posix/posix.Stat.html

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