autocommit 2022-02-15 22:53:12 CET

src/forker/clone3.rs

@@ -0,0 +1,56 @@
+use crate::forker::ForkerError;
+use std::mem;
+use uapi::{c, OwnedFd};
+
+#[derive(Default, Copy, Clone)]
+#[allow(non_camel_case_types, dead_code)]
+struct clone_args {
+    flags: u64,
+    pidfd: u64,
+    child_tid: u64,
+    parent_tid: u64,
+    exit_signal: u64,
+    stack: u64,
+    stack_size: u64,
+    tls: u64,
+    set_tid: u64,
+    set_tid_size: u64,
+    cgroup: u64,
+}
+
+pub enum Forked {
+    Parent { pid: c::pid_t, pidfd: OwnedFd },
+    Child { pidfd: Option<OwnedFd> },
+}
+
+pub fn fork_with_pidfd(pidfd_for_child: bool) -> Result<Forked, ForkerError> {
+    let mut pidfd: c::c_int = 0;
+    let mut args = clone_args {
+        flags: c::CLONE_PIDFD as u64,
+        pidfd: (&mut pidfd as *mut c::c_int) as _,
+        ..Default::default()
+    };
+    let mut child_pidfd = None;
+    if pidfd_for_child {
+        child_pidfd = Some(uapi::pidfd_open(uapi::getpid(), 0).unwrap());
+    }
+    unsafe {
+        let pid = c::syscall(
+            c::SYS_clone3,
+            &mut args as *const _ as usize,
+            mem::size_of::<clone_args>(),
+        );
+        if let Err(e) = uapi::map_err!(pid) {
+            return Err(ForkerError::Fork(e.into()));
+        }
+        let res = if pid == 0 {
+            Forked::Child { pidfd: child_pidfd }
+        } else {
+            Forked::Parent {
+                pid: pid as _,
+                pidfd: OwnedFd::new(pidfd),
+            }
+        };
+        Ok(res)
+    }
+}