Enum SpawnBackend 

pub enum SpawnBackend {
    PosixSpawn,
    Fork,
    Vfork,
    Clone3,
    Clone3Pidfd,
}

Explicit process spawning backend.

Variants

PosixSpawn

Force the use of posix_spawn.

Fork

Force the use of fork/exec.

The fork backend supports explicit SpawnFdPolicy handling before execve.

Vfork

Force the use of vfork/exec.

vfork shares the parent’s address space with the child until it execves (or _exits), so it avoids the page-table work of fork. The child runs only async-signal-safe setup before execve, and the calling thread is blocked until the child execs. Safe for the child because the Linux vfork child inherits a copy of the descriptor table, so SpawnFdPolicy handling works as with SpawnBackend::Fork.

Use only when the shared-address-space semantics are understood: the child must never return from the spawn entry point, and a bug in the child setup can corrupt the parent’s memory.

Clone3

Force the use of clone3(2)/exec (kernel 5.3+).

clone3 with process flags creates a child with copy-on-write memory and a copied descriptor table, like SpawnBackend::Fork, but lets the caller control clone flags directly. Supported by the same child setup as the fork backend. Returns ENOSYS on kernels without clone3.

Clone3Pidfd

Force the use of clone3(2) with CLONE_PIDFD + exec (kernel 5.3+).

Identical to SpawnBackend::Clone3, but the kernel additionally hands the parent a pidfd for the child. The resulting Process carries that pidfd: signaling uses pidfd_send_signal (immune to pid reuse), and exit detection polls the pidfd instead of polling waitpid. Returns ENOSYS on kernels without clone3.

Trait Implementations

impl Clone for SpawnBackend

fn clone(&self) -> SpawnBackend

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for SpawnBackend

impl Debug for SpawnBackend

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

Formats the value using the given formatter.

impl Eq for SpawnBackend

impl PartialEq for SpawnBackend

fn eq(&self, other: &SpawnBackend) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for SpawnBackend