From b4d42897d8ebcdbdd2c9efee495d587c11b5b7fc Mon Sep 17 00:00:00 2001
From: 4lDO2 <4lDO2@protonmail.com>
Date: Fri, 11 Apr 2025 16:09:56 +0200
Subject: [PATCH] Return ERESTART when caller kills itself.

---
 src/procmgr.rs | 43 ++++++++++++++++++++++++++++++-------------
 1 file changed, 30 insertions(+), 13 deletions(-)

diff --git a/src/procmgr.rs b/src/procmgr.rs
index 6547bb389d..81d32de135 100644
--- a/src/procmgr.rs
+++ b/src/procmgr.rs
@@ -31,8 +31,8 @@ use syscall::{
     sig_bit, ContextStatus, ContextVerb, Error, Event, EventFlags, FobtainFdFlags, MapFlags,
     ProcSchemeAttrs, Result, RtSigInfo, SenderInfo, SetSighandlerData, SigProcControl, Sigcontrol,
     EAGAIN, EBADF, EBADFD, ECHILD, EEXIST, EINTR, EINVAL, EIO, ENOENT, ENOSYS, EOPNOTSUPP, EPERM,
-    ESRCH, EWOULDBLOCK, O_CLOEXEC, O_CREAT, PAGE_SIZE, SIGCHLD, SIGCONT, SIGKILL, SIGSTOP, SIGTSTP,
-    SIGTTIN, SIGTTOU,
+    ERESTART, ESRCH, EWOULDBLOCK, O_CLOEXEC, O_CREAT, PAGE_SIZE, SIGCHLD, SIGCONT, SIGKILL,
+    SIGSTOP, SIGTSTP, SIGTTIN, SIGTTOU,
 };
 
 #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
@@ -880,8 +880,6 @@ impl<'a> ProcScheme<'a> {
                         else {
                             return Response::ready_err(EINVAL, op);
                         };
-                        let mut killed_self = false;
-
                         let mode = match verb {
                             ProcCall::Kill => KillMode::Idempotent,
                             ProcCall::Sigq => KillMode::Queued({
@@ -895,7 +893,6 @@ impl<'a> ProcScheme<'a> {
                             _ => unreachable!(),
                         };
 
-                        let is_sigchld_to_parent = false;
                         Ready(Response::new(
                             self.on_kill(fd_pid, target, signal, mode, awoken)
                                 .map(|()| 0),
@@ -1451,9 +1448,12 @@ impl<'a> ProcScheme<'a> {
         signal: u8,
         awoken: &mut VecDeque<VirtualId>,
     ) -> Result<()> {
-        let mut killed_self = false; // TODO
+        let mut killed_self = false;
+
         let is_sigchld_to_parent = false;
+
         let caller_pid = thread.borrow().pid; // TODO: allow this to be specified?
+
         self.on_send_sig(
             caller_pid,
             KillTarget::Thread(Rc::clone(thread)),
@@ -1462,7 +1462,14 @@ impl<'a> ProcScheme<'a> {
             KillMode::Idempotent,
             is_sigchld_to_parent,
             awoken,
-        )
+        )?;
+
+        if killed_self {
+            // TODO: is this the most accurate error code?
+            Err(Error::new(ERESTART))
+        } else {
+            Ok(())
+        }
     }
     pub fn on_kill(
         &mut self,
@@ -1475,8 +1482,12 @@ impl<'a> ProcScheme<'a> {
         log::trace!("KILL(from {caller_pid:?}) TARGET {target:?} {signal} {mode:?}");
         let mut num_succeeded = 0;
 
-        let mut killed_self = false; // TODO
-        let is_sigchld_to_parent = false; // TODO
+        // if this is set and we would otherwise have succeeded, return EINTR so it can check its
+        // own mask
+        let mut killed_self = false;
+
+        // SIGCHLD to parent are not generated by on_kill, but by on_send_sig itself
+        let is_sigchld_to_parent = false;
 
         let match_grp = match target {
             ProcKillTarget::SingleProc(pid) => {
@@ -1522,7 +1533,11 @@ impl<'a> ProcScheme<'a> {
             }
         }
 
-        Ok(())
+        if killed_self {
+            Err(Error::new(ERESTART))
+        } else {
+            Ok(())
+        }
     }
     pub fn on_send_sig(
         &self,
@@ -1567,9 +1582,11 @@ impl<'a> ProcScheme<'a> {
         }
 
         let result = (|| {
-            // FIXME
-            let is_self = false;
-            //let is_self = context::is_current(&context_lock);
+            // XXX: It's not currently possible for procmgr to know what thread called, so the
+            // EINTR will be coarser. That shouldn't affect program logic though, since the
+            // trampoline always checks the masks anyway.
+            // TODO: allow regular kill (alongside thread-kill) to operate on *thread fds*?
+            let is_self = target_pid == caller_pid;
 
             // If sig = 0, test that process exists and can be signalled, but don't send any
             // signal.