Struct Fs 

pub struct Fs {
    pub root: Vec<u8>,
    pub bindings: Vec<Binding>,
    pub identity: bool,
    pub proc_is_host: bool,
    root_pin: Pin,
    pins: Vec<Pin>,
    id: u64,
    cache: Arc<DirCache>,
    pub procs: Arc<ProcTable>,
}

The guest filesystem view: a root directory plus bind mounts.

Fields

root: Vec<u8>

Host directory serving as guest /, no trailing slash.

bindings: Vec<Binding>

Bindings sorted so that longer guest prefixes come first.

identity: bool

True when root is / and there are no bindings: translation is a no-op.

proc_is_host: bool

True when guest /proc is the host’s: its magic links mean what they mean on the host.

root_pin: Pin

The root’s host side, held open.

pins: Vec<Pin>

Each binding’s host side, held open; same order as bindings.

id: u64

Identifies this view’s entries in the shared directory cache.

cache: Arc<DirCache>

Directory cache shared with every other view of the supervisor.

procs: Arc<ProcTable>

Per-process records: the program each process runs, since the kernel’s own /proc/<pid>/exe names the dynamic loader after an exec rewrite, and without ptrace the working directory too.

Implementations

impl Fs

pub fn new(config: &Config) -> Fs

Builds the view from the parsed configuration with its own process table and directory cache.

Arguments

• config - Parsed command line. Bindings are normalized and sorted.

pub fn with_procs(config: &Config, procs: Arc<ProcTable>) -> Fs

Builds the view from the parsed configuration over a shared process table, with a directory cache of its own.

Arguments

• config - Parsed command line. Bindings are normalized and sorted.
• procs - Process table shared with the supervisor.

pub fn with_cache( config: &Config, procs: Arc<ProcTable>, cache: Arc<DirCache>, ) -> Fs

Builds the view from the parsed configuration over a shared process table and a shared directory cache.

The root is made absolute, since it is used from the alias directory as well (loader aliases, the exec shim’s records).

Arguments

• config - Parsed command line. Bindings are normalized and sorted.
• procs - Process table shared with the supervisor.
• cache - Directory cache shared with the supervisor’s other views.

fn canonicalize_bindings(&mut self)

Rewrites every binding’s guest path to the canonical form lookups use.

A lookup is canonicalized through the view before the binding table is consulted, so a guest path given through a symlink of the rootfs, such as /lib/ld-linux.so.2 on a merged-usr host where /lib points to usr/lib, would never match unless the table holds the /usr/lib/ld-linux.so.2 the lookup resolves to. The final component is kept as given, and a path whose intermediate components are missing stays lexical, as the walk stops there. The table is re-sorted and the identity flag recomputed when anything changed.

pub fn cache_get(&self, guest: &[u8]) -> Option<Arc<OwnedFd>>

The pinned directory of a canonical guest directory the cache has seen in this view.

Arguments

• guest - Canonical absolute guest path.

pub fn cache_put(&self, guest: &[u8], fd: Arc<OwnedFd>)

Records the directory guest resolved to in this view.

Arguments

• guest - Canonical absolute guest path.
• fd - Its O_PATH descriptor.

pub fn mount_pin(&self, guest: &[u8]) -> Option<Option<Arc<OwnedFd>>>

The pinned host side of the binding whose guest path is exactly guest, or of the root for /.

Returns

None when guest is no mount point of this view; Some(None) when it is one whose host side does not exist.

pub fn binding_below(&self, guest: &[u8]) -> bool

Whether a binding lies below guest, which then stands in the view as a directory even where the host side has nothing under the name: in a rootfs the placeholders of glue could not be made in, say.

Arguments

• guest - Canonical absolute guest path.

pub fn pin_for_guest<'a>( &self, guest: &'a [u8], ) -> (Option<Arc<OwnedFd>>, &'a [u8])

The pinned mount point under which guest lies, and the path from there.

Arguments

• guest - Canonical absolute guest path.

Returns

The binding’s (or root’s) descriptor, None when its host side does not exist, and the remainder of guest below it with its leading slash (empty for the mount point itself).

pub fn flush_cache(&self)

Forgets every cached directory of every view sharing the cache.

pub fn exe_of(&self, tid: i32) -> Option<Vec<u8>>

The recorded guest program of thread tid, if any.

Arguments

• tid - Thread or process id as it appears in a /proc/<n> path.

pub fn virtual_cwd(&self, tid: i32) -> Option<Vec<u8>>

The virtual working directory of thread tid, when cwd is virtual (no ptrace).

Arguments

• tid - Thread or process id.

pub fn binding_for_guest(&self, guest: &[u8]) -> Option<&Binding>

Finds the binding whose guest prefix covers guest, if any.

Arguments

• guest - Absolute, lexically clean guest path.

pub fn binding_for_host(&self, host: &[u8]) -> Option<&Binding>

Finds the binding whose host prefix covers host, preferring the longest.

Arguments

• host - Absolute host path.

pub fn substitute_guest_to_host(&self, guest: &[u8]) -> Vec<u8>

Substitutes the guest prefix of an absolute guest path with its host prefix.

This is purely lexical: no symlink is followed. Use crate::fs::translate::translate_path for a real translation.

Arguments

• guest - Absolute guest path.

Returns

The host path the guest path maps to.

pub fn substitute_host_to_guest(&self, host: &[u8]) -> Option<Vec<u8>>

Substitutes the host prefix of a host path with its guest prefix.

Arguments

• host - Absolute host path.

Returns

The guest path, or None when the host path is not visible in the guest.

Trait Implementations

impl Debug for Fs

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

Formats the value using the given formatter.