From ddf0ba22e163112ab032e04d2a93e2f0a73bab36 Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Fri, 6 Jun 2025 16:11:25 +0200
Subject: [PATCH 1/2] Use `Command::exec` to run `rustc`/`cargo` commands to
 ensure that if they exit because of a signal, it will be displayed at the top
 level

---
 build_system/src/rust_tools.rs | 34 +++++++++++++++++++++-------------
 build_system/src/utils.rs      | 13 ++-----------
 2 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/build_system/src/rust_tools.rs b/build_system/src/rust_tools.rs
index 105f5eebe24..7a0c5962919 100644
--- a/build_system/src/rust_tools.rs
+++ b/build_system/src/rust_tools.rs
@@ -1,12 +1,11 @@
 use std::collections::HashMap;
 use std::ffi::OsStr;
+#[cfg(unix)]
+use std::os::unix::process::CommandExt;
 use std::path::PathBuf;
 
 use crate::config::ConfigInfo;
-use crate::utils::{
-    get_toolchain, run_command_with_output_and_env_no_err, rustc_toolchain_version_info,
-    rustc_version_info,
-};
+use crate::utils::{get_toolchain, rustc_toolchain_version_info, rustc_version_info};
 
 fn args(command: &str) -> Result<Option<Vec<String>>, String> {
     // We skip the binary and the "cargo"/"rustc" option.
@@ -97,6 +96,22 @@ impl RustcTools {
     }
 }
 
+fn exec(input: &[&dyn AsRef<OsStr>], env: &HashMap<String, String>) -> Result<(), String> {
+    #[cfg(unix)]
+    {
+        let error = crate::utils::get_command_inner(input, None, Some(env)).exec();
+        eprintln!("execvp syscall failed: {error:?}");
+        std::process::exit(1);
+    }
+    #[cfg(not(unix))]
+    {
+        if crate::utils::run_command_with_output_and_env_no_err(input, None, Some(env)).is_err() {
+            std::process::exit(1);
+        }
+        Ok(())
+    }
+}
+
 pub fn run_cargo() -> Result<(), String> {
     let Some(mut tools) = RustcTools::new("cargo")? else { return Ok(()) };
     let rustflags = tools.env.get("RUSTFLAGS").cloned().unwrap_or_default();
@@ -105,11 +120,7 @@ pub fn run_cargo() -> Result<(), String> {
     for arg in &tools.args {
         command.push(arg);
     }
-    if run_command_with_output_and_env_no_err(&command, None, Some(&tools.env)).is_err() {
-        std::process::exit(1);
-    }
-
-    Ok(())
+    exec(&command, &tools.env)
 }
 
 pub fn run_rustc() -> Result<(), String> {
@@ -118,8 +129,5 @@ pub fn run_rustc() -> Result<(), String> {
     for arg in &tools.args {
         command.push(arg);
     }
-    if run_command_with_output_and_env_no_err(&command, None, Some(&tools.env)).is_err() {
-        std::process::exit(1);
-    }
-    Ok(())
+    exec(&command, &tools.env)
 }
diff --git a/build_system/src/utils.rs b/build_system/src/utils.rs
index ca177a5feb8..da91b3a8c29 100644
--- a/build_system/src/utils.rs
+++ b/build_system/src/utils.rs
@@ -1,7 +1,5 @@
 use std::collections::HashMap;
 use std::ffi::OsStr;
-#[cfg(unix)]
-use std::ffi::c_int;
 use std::fmt::Debug;
 use std::fs;
 #[cfg(unix)]
@@ -9,11 +7,6 @@ use std::os::unix::process::ExitStatusExt;
 use std::path::{Path, PathBuf};
 use std::process::{Command, ExitStatus, Output};
 
-#[cfg(unix)]
-unsafe extern "C" {
-    fn raise(signal: c_int) -> c_int;
-}
-
 fn exec_command(
     input: &[&dyn AsRef<OsStr>],
     cwd: Option<&Path>,
@@ -27,9 +20,6 @@ fn exec_command(
     #[cfg(unix)]
     {
         if let Some(signal) = status.signal() {
-            unsafe {
-                raise(signal as _);
-            }
             // In case the signal didn't kill the current process.
             return Err(command_error(input, &cwd, format!("Process received signal {}", signal)));
         }
@@ -37,7 +27,7 @@ fn exec_command(
     Ok(status)
 }
 
-fn get_command_inner(
+pub(crate) fn get_command_inner(
     input: &[&dyn AsRef<OsStr>],
     cwd: Option<&Path>,
     env: Option<&HashMap<String, String>>,
@@ -136,6 +126,7 @@ pub fn run_command_with_output_and_env(
     Ok(())
 }
 
+#[cfg(not(unix))]
 pub fn run_command_with_output_and_env_no_err(
     input: &[&dyn AsRef<OsStr>],
     cwd: Option<&Path>,

From d14a49d89c21a2f1dfccbefae22f45efc832c79e Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Sun, 8 Jun 2025 11:48:01 +0200
Subject: [PATCH 2/2] Add documentation about why we use `exec`

---
 build_system/src/rust_tools.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/build_system/src/rust_tools.rs b/build_system/src/rust_tools.rs
index 7a0c5962919..7e3e37a30a8 100644
--- a/build_system/src/rust_tools.rs
+++ b/build_system/src/rust_tools.rs
@@ -99,6 +99,10 @@ impl RustcTools {
 fn exec(input: &[&dyn AsRef<OsStr>], env: &HashMap<String, String>) -> Result<(), String> {
     #[cfg(unix)]
     {
+        // We use `exec` to call the `execvp` syscall instead of creating a new process where the
+        // command will be executed because very few signals can actually kill a current process,
+        // so if segmentation fault (SIGSEGV signal) happens and we raise to the current process,
+        // it will simply do nothing and we won't have the nice error message for the shell.
         let error = crate::utils::get_command_inner(input, None, Some(env)).exec();
         eprintln!("execvp syscall failed: {error:?}");
         std::process::exit(1);