From 0528a6af22c9b5641dcbe0c4991a7a65b5768479 Mon Sep 17 00:00:00 2001
From: Elnath <elnathbeta@gmail.com>
Date: Fri, 18 Apr 2025 18:23:10 +0200
Subject: [PATCH] Program forks and parent waits for child

---
 src/main.rs | 40 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 35 insertions(+), 5 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 0687f85..5d8c7e2 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,9 +1,39 @@
-use nix::unistd::execv;
+use nix::unistd::{execv, fork, ForkResult};
 use std::ffi::CString;
+use std::process::ExitCode;
+use nix::sys::wait::{waitid, WaitPidFlag, WaitStatus};
 
-fn main() {
-    println!("I am executing {}!", env!("TEST_PROG_PATH"));
+fn main() -> ExitCode {
+    let child_exec_path = CString::new(env!("TEST_PROG_PATH")).unwrap();
 
-    let path = CString::new(env!("TEST_PROG_PATH")).unwrap();
-    execv(&path, &[&path]).unwrap();
+    match unsafe{fork()} {
+        Ok(ForkResult::Child) => {
+            // ⚠️ There is a limited amount of things that can be done here, see fork's safety
+            execv(&child_exec_path, &[&child_exec_path]).unwrap();
+            unreachable!();
+        }
+        Ok(ForkResult::Parent { child: child_pid }) => {
+            println!("✔️ Started child {child_pid}");
+            println!("⏳️ Waiting for child to exit...");
+            use nix::sys::wait::Id::Pid;
+            match waitid(Pid(child_pid), WaitPidFlag::WEXITED) {
+                Err(e) => {
+                    println!("❌ Wait failed: {e}");
+                    ExitCode::FAILURE
+                }
+                Ok(WaitStatus::Exited(_pid, exit_code)) => {
+                    println!("👋 child exited with code {exit_code}");
+                    ExitCode::SUCCESS
+                }
+                Ok(status) => {
+                    println!("⚠️ Unexpected status from wait! {status:#?}");
+                    ExitCode::FAILURE
+                }
+            }
+        }
+        Err(e) => {
+            println!("❌ Fork failed: {e}");
+            ExitCode::FAILURE
+        }
+    }
 }