fix: terminate pane sessions on close

4 files changed, 143 insertions, 3 deletions

diff --git a/src/platform/fallback.rs b/src/platform/fallback.rs
index 7bcd23c5..4bf78352 100644
--- a/src/platform/fallback.rs
+++ b/src/platform/fallback.rs
@@ -1,6 +1,6 @@
 use std::path::PathBuf;
 
-use super::ForegroundJob;
+use super::{ForegroundJob, Signal};
 
 /// Unsupported platform stub.
 pub fn foreground_job(_child_pid: u32) -> Option<ForegroundJob> {
@@ -11,3 +11,16 @@ pub fn foreground_job(_child_pid: u32) -> Option<ForegroundJob> {
 pub fn process_cwd(_pid: u32) -> Option<PathBuf> {
     None
 }
+
+/// Unsupported platform stub.
+pub fn session_processes(_child_pid: u32) -> Vec<u32> {
+    Vec::new()
+}
+
+/// Unsupported platform stub.
+pub fn signal_processes(_pids: &[u32], _signal: Signal) {}
+
+/// Unsupported platform stub.
+pub fn process_exists(_pid: u32) -> bool {
+    false
+}
diff --git a/src/platform/linux.rs b/src/platform/linux.rs
index 10695e92..b6fc0272 100644
--- a/src/platform/linux.rs
+++ b/src/platform/linux.rs
@@ -1,6 +1,6 @@
 use std::path::PathBuf;
 
-use super::{ForegroundJob, ForegroundProcess};
+use super::{ForegroundJob, ForegroundProcess, Signal};
 
 /// Collect the foreground terminal job for a given child PID.
 pub fn foreground_job(child_pid: u32) -> Option<ForegroundJob> {
@@ -87,3 +87,64 @@ pub fn process_cwd(pid: u32) -> Option<PathBuf> {
     }
     std::fs::read_link(format!("/proc/{pid}/cwd")).ok()
 }
+
+pub fn session_processes(child_pid: u32) -> Vec<u32> {
+    let Some(session_id) = process_session_id(child_pid) else {
+        return Vec::new();
+    };
+
+    let mut pids = Vec::new();
+    for entry in std::fs::read_dir("/proc").into_iter().flatten().flatten() {
+        let file_name = entry.file_name();
+        let Some(pid_str) = file_name.to_str() else {
+            continue;
+        };
+        if !pid_str.bytes().all(|b| b.is_ascii_digit()) {
+            continue;
+        }
+
+        let Ok(pid) = pid_str.parse::<u32>() else {
+            continue;
+        };
+        if process_session_id(pid) == Some(session_id) {
+            pids.push(pid);
+        }
+    }
+    pids
+}
+
+pub fn signal_processes(pids: &[u32], signal: Signal) {
+    let sig = match signal {
+        Signal::Hangup => libc::SIGHUP,
+        Signal::Terminate => libc::SIGTERM,
+        Signal::Kill => libc::SIGKILL,
+    };
+
+    for &pid in pids {
+        if pid == 0 {
+            continue;
+        }
+        unsafe {
+            libc::kill(pid as i32, sig);
+        }
+    }
+}
+
+pub fn process_exists(pid: u32) -> bool {
+    if pid == 0 {
+        return false;
+    }
+    let result = unsafe { libc::kill(pid as i32, 0) };
+    if result == 0 {
+        true
+    } else {
+        std::io::Error::last_os_error().raw_os_error() == Some(libc::EPERM)
+    }
+}
+
+fn process_session_id(pid: u32) -> Option<i32> {
+    let stat = std::fs::read_to_string(format!("/proc/{pid}/stat")).ok()?;
+    let rest = stat.get(stat.rfind(')')? + 2..)?;
+    let fields: Vec<&str> = rest.split_whitespace().collect();
+    fields.get(3)?.parse().ok()
+}
diff --git a/src/platform/macos.rs b/src/platform/macos.rs
index e2f368f8..82de0c5b 100644
--- a/src/platform/macos.rs
+++ b/src/platform/macos.rs
@@ -2,7 +2,7 @@ use std::ffi::OsStr;
 use std::os::unix::ffi::OsStrExt;
 use std::path::{Path, PathBuf};
 
-use super::{ForegroundJob, ForegroundProcess};
+use super::{ForegroundJob, ForegroundProcess, Signal};
 
 /// Collect the foreground terminal job for a given child PID.
 pub fn foreground_job(child_pid: u32) -> Option<ForegroundJob> {
@@ -284,3 +284,62 @@ pub fn process_cwd(pid: u32) -> Option<PathBuf> {
     }
     Some(PathBuf::from(OsStr::from_bytes(&vip_path[..nul])))
 }
+
+pub fn session_processes(child_pid: u32) -> Vec<u32> {
+    if child_pid == 0 {
+        return Vec::new();
+    }
+
+    let target_session = unsafe { libc::getsid(child_pid as libc::c_int) };
+    if target_session <= 0 {
+        return Vec::new();
+    }
+
+    let mut pids = vec![0i32; 4096];
+    let bytes = unsafe {
+        libc::proc_listallpids(
+            pids.as_mut_ptr() as *mut libc::c_void,
+            (pids.len() * std::mem::size_of::<i32>()) as libc::c_int,
+        )
+    };
+    if bytes <= 0 {
+        return Vec::new();
+    }
+
+    let count = (bytes as usize) / std::mem::size_of::<i32>();
+    pids.into_iter()
+        .take(count)
+        .filter(|pid| *pid > 0)
+        .filter(|pid| unsafe { libc::getsid(*pid) } == target_session)
+        .map(|pid| pid as u32)
+        .collect()
+}
+
+pub fn signal_processes(pids: &[u32], signal: Signal) {
+    let sig = match signal {
+        Signal::Hangup => libc::SIGHUP,
+        Signal::Terminate => libc::SIGTERM,
+        Signal::Kill => libc::SIGKILL,
+    };
+
+    for &pid in pids {
+        if pid == 0 {
+            continue;
+        }
+        unsafe {
+            libc::kill(pid as libc::c_int, sig);
+        }
+    }
+}
+
+pub fn process_exists(pid: u32) -> bool {
+    if pid == 0 {
+        return false;
+    }
+    let result = unsafe { libc::kill(pid as libc::c_int, 0) };
+    if result == 0 {
+        true
+    } else {
+        std::io::Error::last_os_error().raw_os_error() == Some(libc::EPERM)
+    }
+}
diff --git a/src/platform/mod.rs b/src/platform/mod.rs
index ade86249..8023cd11 100644
--- a/src/platform/mod.rs
+++ b/src/platform/mod.rs
@@ -17,6 +17,13 @@ pub struct ForegroundJob {
     pub processes: Vec<ForegroundProcess>,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Signal {
+    Hangup,
+    Terminate,
+    Kill,
+}
+
 #[cfg(target_os = "linux")]
 mod linux;
 #[cfg(target_os = "linux")]