Increase nofile rlimit, restore for spawned processes

src/api.rs

@@ -60,6 +60,7 @@ use crate::{
     render::util::snapshot::capture_snapshots_on_output,
     state::{State, WithState},
     tag::{Tag, TagId},
+    util::restore_nofile_rlimit,
 };
 
 type ResponseStream<T> = Pin<Box<dyn Stream<Item = Result<T, Status>> + Send>>;
@@ -587,22 +588,30 @@ impl process_service_server::ProcessService for ProcessService {
                 }
             }
 
-            let Ok(mut child) = tokio::process::Command::new(OsString::from(arg0.clone()))
-                .stdin(match has_callback {
-                    true => Stdio::piped(),
-                    false => Stdio::null(),
-                })
-                .stdout(match has_callback {
-                    true => Stdio::piped(),
-                    false => Stdio::null(),
-                })
-                .stderr(match has_callback {
-                    true => Stdio::piped(),
-                    false => Stdio::null(),
-                })
-                .args(command)
-                .spawn()
-            else {
+            let mut cmd = tokio::process::Command::new(OsString::from(arg0.clone()));
+
+            cmd.stdin(match has_callback {
+                true => Stdio::piped(),
+                false => Stdio::null(),
+            })
+            .stdout(match has_callback {
+                true => Stdio::piped(),
+                false => Stdio::null(),
+            })
+            .stderr(match has_callback {
+                true => Stdio::piped(),
+                false => Stdio::null(),
+            })
+            .args(command);
+
+            unsafe {
+                cmd.pre_exec(|| {
+                    restore_nofile_rlimit();
+                    Ok(())
+                });
+            }
+
+            let Ok(mut child) = cmd.spawn() else {
                 warn!("Tried to run {arg0}, but it doesn't exist",);
                 return;
             };

src/lib.rs

@@ -13,4 +13,5 @@ pub mod protocol;
 pub mod render;
 pub mod state;
 pub mod tag;
+pub mod util;
 pub mod window;

src/main.rs

@@ -18,6 +18,7 @@ use pinnacle::{
     cli::{self, Cli},
     config::{get_config_dir, parse_metaconfig, Metaconfig},
     state::State,
+    util::increase_nofile_rlimit,
 };
 use smithay::reexports::{calloop::EventLoop, rustix::process::geteuid};
 use tracing::{error, info, warn};
@@ -63,6 +64,8 @@ async fn main() -> anyhow::Result<()> {
 
     info!("Starting Pinnacle (commit {})", env!("VERGEN_GIT_SHA"));
 
+    increase_nofile_rlimit();
+
     set_log_panic_hook();
 
     let Some(cli) = Cli::parse_and_prompt() else {

src/util.rs

@@ -0,0 +1,34 @@
+use std::sync::atomic::{AtomicU64, Ordering};
+
+use smithay::reexports::rustix::process::{getrlimit, setrlimit, Resource, Rlimit};
+use tracing::warn;
+
+static NOFILE_RLIMIT_CURRENT: AtomicU64 = AtomicU64::new(0);
+static NOFILE_RLIMIT_MAXIMUM: AtomicU64 = AtomicU64::new(0);
+
+pub fn increase_nofile_rlimit() {
+    let mut limits = getrlimit(Resource::Nofile);
+
+    NOFILE_RLIMIT_CURRENT.store(limits.current.unwrap_or(0), Ordering::SeqCst);
+    NOFILE_RLIMIT_MAXIMUM.store(limits.maximum.unwrap_or(0), Ordering::SeqCst);
+
+    limits.current = limits.maximum;
+
+    if let Err(err) = setrlimit(Resource::Nofile, limits) {
+        warn!("Failed to raise nofile limit: {err}");
+    }
+}
+
+pub fn restore_nofile_rlimit() {
+    let current = NOFILE_RLIMIT_CURRENT.load(Ordering::SeqCst);
+    let maximum = NOFILE_RLIMIT_MAXIMUM.load(Ordering::SeqCst);
+
+    let limits = Rlimit {
+        current: (current > 0).then_some(current),
+        maximum: (maximum > 0).then_some(maximum),
+    };
+
+    if let Err(err) = setrlimit(Resource::Nofile, limits) {
+        warn!("Failed to restore nofile limit: {err}");
+    }
+}