What is the usage of open_by_handle_at(2)?
I learn this system call from docker breakout tech with CAP_DAC_READ_SEARCH.
I am wondering what is this system call originally designed for? Or is there any other typical and common usage of it? Because after a while of searching, I found that the most significant usage of open_by_handle_at(2) is to break out from containers…
From man open_by_handle:
These system calls are designed for use by user-space file servers. For example, a user-space NFS server might generate a file handle and pass it to an NFS client. Later, when the client wants to open the file, it could pass the handle back to the server. This sort of functionality allows a user-space file server to operate in a stateless fashion with respect to the files it serves.
Answered By – KamilCuk