Don't propagate overwritten RUST_{,LIB_}BACKTRACE

src/main.rs

@@ -39,6 +39,8 @@ use tracing_subscriber::EnvFilter;
 use utils::spawn;
 use watcher::Watcher;
 
+use crate::utils::{REMOVE_ENV_RUST_BACKTRACE, REMOVE_ENV_RUST_LIB_BACKTRACE};
+
 #[derive(Parser)]
 #[command(author, version, about, long_about = None)]
 struct Cli {
@@ -51,9 +53,14 @@ struct Cli {
 }
 
 fn main() {
-    env::set_var("RUST_BACKTRACE", "1");
+    // Set backtrace defaults if not set.
+    if env::var_os("RUST_BACKTRACE").is_none() {
+        env::set_var("RUST_BACKTRACE", "1");
+        REMOVE_ENV_RUST_BACKTRACE.store(true, Ordering::Relaxed);
+    }
     if env::var_os("RUST_LIB_BACKTRACE").is_none() {
         env::set_var("RUST_LIB_BACKTRACE", "0");
+        REMOVE_ENV_RUST_LIB_BACKTRACE.store(true, Ordering::Relaxed);
     }
 
     let is_systemd_service = env::var_os("NOTIFY_SOCKET").is_some();

src/utils.rs

@@ -5,6 +5,7 @@ use std::os::unix::process::CommandExt;
 use std::path::PathBuf;
 use std::process::{Command, Stdio};
 use std::ptr::null_mut;
+use std::sync::atomic::{AtomicBool, Ordering};
 use std::time::Duration;
 
 use anyhow::{ensure, Context};
@@ -53,6 +54,9 @@ pub fn make_screenshot_path(config: &Config) -> anyhow::Result<Option<PathBuf>>
     Ok(Some(path))
 }
 
+pub static REMOVE_ENV_RUST_BACKTRACE: AtomicBool = AtomicBool::new(false);
+pub static REMOVE_ENV_RUST_LIB_BACKTRACE: AtomicBool = AtomicBool::new(false);
+
 /// Spawns the command to run independently of the compositor.
 pub fn spawn(command: impl AsRef<OsStr>, args: impl IntoIterator<Item = impl AsRef<OsStr>>) {
     let _span = tracy_client::span!();
@@ -66,6 +70,14 @@ pub fn spawn(command: impl AsRef<OsStr>, args: impl IntoIterator<Item = impl AsR
         .stdout(Stdio::null())
         .stderr(Stdio::null());
 
+    // Remove RUST_BACKTRACE and RUST_LIB_BACKTRACE from the environment if needed.
+    if REMOVE_ENV_RUST_BACKTRACE.load(Ordering::Relaxed) {
+        process.env_remove("RUST_BACKTRACE");
+    }
+    if REMOVE_ENV_RUST_LIB_BACKTRACE.load(Ordering::Relaxed) {
+        process.env_remove("RUST_LIB_BACKTRACE");
+    }
+
     // Double-fork to avoid having to waitpid the child.
     unsafe {
         process.pre_exec(|| {