Struct ThreadFs 

pub struct ThreadFs {
    pub cwd: Mutex<String>,
    pub umask: AtomicU32,
}

Per-thread filesystem state for CLONE_FS support.

Each thread has a reference-counted ThreadFs that holds the thread’s current working directory (cwd) and file creation mask (umask). When CLONE_FS is set during clone(), the parent and child share the same Arc<ThreadFs>, so changes to cwd or umask in one thread are visible to the other. When CLONE_FS is not set, the child receives an independent copy (via clone_copy).

This mirrors the Linux kernel’s struct fs_struct semantics.

Fields

cwd: Mutex<String>

Current working directory path. Protected by a spinlock because it can be read from syscall paths (getcwd) and modified from others (chdir) concurrently.

umask: AtomicU32

File creation mask (umask). Atomic because it can be read/written from concurrent syscall paths without holding a lock.

Implementations

impl ThreadFs

pub fn new_root() -> Arc<Self>

Create a new root filesystem state with cwd=“/” and umask=0o022.

Used for the initial thread of a new process.

pub fn clone_shared(src: &Arc<Self>) -> Arc<Self>

Share the filesystem state (CLONE_FS semantics).

Returns a clone of the Arc, so parent and child reference the same underlying ThreadFs. Changes to cwd or umask in either thread are visible to the other.

pub fn clone_copy(src: &Arc<Self>) -> Arc<Self>

Copy the filesystem state (non-CLONE_FS semantics).

Creates a new independent ThreadFs with the same cwd and umask values. Subsequent changes in either thread are isolated.

Trait Implementations

impl Debug for ThreadFs

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.