From c4cf4336c823a1d5681523e6ef5cdfaa270f71ac Mon Sep 17 00:00:00 2001
From: tcmal <me@aria.rip>
Date: Fri, 21 Jun 2024 22:27:01 +0100
Subject: implement cleanup_process_children

---
 Cargo.lock  | 33 ++++++++++++++++++++++++++++++++-
 Cargo.toml  |  1 +
 src/main.rs | 25 ++++++++++++++++++++++---
 3 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 0bb8497..34714c9 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -8,14 +8,33 @@ version = "1.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
+[[package]]
+name = "bitflags"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf4b9d6a944f767f8e5e0db018570623c85f3d925ac718db4e06d0187adb21c1"
+
 [[package]]
 name = "blow"
 version = "0.1.0"
 dependencies = [
+ "nix",
  "xcb",
  "xkeysym",
 ]
 
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "cfg_aliases"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
+
 [[package]]
 name = "libc"
 version = "0.2.155"
@@ -28,6 +47,18 @@ version = "2.7.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6c8640c5d730cb13ebd907d8d04b52f55ac9a2eec55b440c8892f40d56c76c1d"
 
+[[package]]
+name = "nix"
+version = "0.29.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "71e2746dc3a24dd78b3cfcb7be93368c6de9963d30f43a6a73998a9cf4b17b46"
+dependencies = [
+ "bitflags 2.5.0",
+ "cfg-if",
+ "cfg_aliases",
+ "libc",
+]
+
 [[package]]
 name = "quick-xml"
 version = "0.30.0"
@@ -43,7 +74,7 @@ version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "02e75181b5a62b6eeaa72f303d3cef7dbb841e22885bf6d3e66fe23e88c55dc6"
 dependencies = [
- "bitflags",
+ "bitflags 1.3.2",
  "libc",
  "quick-xml",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index e0ebbcb..0bfdea5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,5 +4,6 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+nix = { version = "0.29.0", features = ["signal"] }
 xcb = { version = "1.4.0", features = ["xinerama"] }
 xkeysym = "0.2.0"
diff --git a/src/main.rs b/src/main.rs
index 09ef1f2..a5091ad 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -21,6 +21,13 @@
 use clients::ClientState;
 use conn_info::Connection;
 pub use error::*;
+use nix::{
+    sys::{
+        signal::{sigaction, SaFlags, SigAction, SigHandler, SigSet, Signal},
+        wait::{waitpid, WaitPidFlag},
+    },
+    unistd::Pid,
+};
 use xcb::{
     x::{self, PropertyNotifyEvent},
     Connection as RawConnection, Event, Extension,
@@ -117,7 +124,19 @@ impl<'a> WM<'a> {
 /// Cleanup this process' children and set some flags.
 /// This is necessary when used with `startx`.
 fn cleanup_process_children() {
-    // TODO: dont transform children into zombies when they terminate
-    // TODO: cleanup zombies
-    // todo!()
+    unsafe {
+        // Don't transform children into zombies when they terminate
+        sigaction(
+            Signal::SIGCHLD,
+            &SigAction::new(
+                SigHandler::SigIgn,
+                SaFlags::SA_NOCLDSTOP | SaFlags::SA_NOCLDWAIT | SaFlags::SA_RESTART,
+                SigSet::empty(),
+            ),
+        )
+        .unwrap();
+
+        // Immediately wait for zombie processes to die - sometimes these come from startx.
+        while let Ok(_) = waitpid(Pid::from_raw(-1), Some(WaitPidFlag::WNOHANG)) {}
+    };
 }
-- 
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