portal: start portal automatically with compositor

src/utils/clone3.rs

@@ -0,0 +1,59 @@
+use {
+    crate::forker::ForkerError,
+    std::mem,
+    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 _,
+        exit_signal: c::SIGCHLD 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)
+    }
+}

src/utils/process_name.rs

@@ -0,0 +1,8 @@
+use uapi::{c, IntoUstr};
+
+pub fn set_process_name(name: &str) {
+    unsafe {
+        let name = name.into_ustr();
+        c::prctl(c::PR_SET_NAME, name.as_ptr());
+    }
+}

src/utils/vecdeque_ext.rs

@@ -0,0 +1,35 @@
+use std::{
+    collections::{Bound, VecDeque},
+    ops::RangeBounds,
+};
+
+pub trait VecDequeExt<T> {
+    fn get_slices(&self, range: impl RangeBounds<usize>) -> (&[T], &[T]);
+}
+
+impl<T> VecDequeExt<T> for VecDeque<T> {
+    fn get_slices(&self, range: impl RangeBounds<usize>) -> (&[T], &[T]) {
+        let (l, r) = self.as_slices();
+        let start = match range.start_bound().cloned() {
+            Bound::Included(n) => n,
+            Bound::Excluded(n) => n + 1,
+            Bound::Unbounded => 0,
+        };
+        let end = match range.end_bound().cloned() {
+            Bound::Included(n) => n + 1,
+            Bound::Excluded(n) => n,
+            Bound::Unbounded => self.len(),
+        };
+        let left = {
+            let lo = start.min(l.len());
+            let hi = end.min(l.len());
+            &l[lo..hi]
+        };
+        let right = {
+            let lo = start.saturating_sub(l.len());
+            let hi = end.saturating_sub(l.len());
+            &r[lo..hi]
+        };
+        (left, right)
+    }
+}