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use std::path::PathBuf;
use super::{ForegroundJob, ForegroundProcess};
/// Collect the foreground terminal job for a given child PID.
pub fn foreground_job(child_pid: u32) -> Option<ForegroundJob> {
let tpgid = foreground_pgid(child_pid)? as u32;
let mut processes = Vec::new();
for entry in std::fs::read_dir("/proc").ok()? {
let entry = entry.ok()?;
let file_name = entry.file_name();
let pid_str = file_name.to_str()?;
if !pid_str.bytes().all(|b| b.is_ascii_digit()) {
continue;
}
let pid: u32 = match pid_str.parse() {
Ok(pid) => pid,
Err(_) => continue,
};
let Some((pgrp, name)) = process_pgrp_and_comm(pid) else {
continue;
};
if pgrp as u32 != tpgid {
continue;
}
processes.push(ForegroundProcess {
pid,
name,
argv0: None,
cmdline: process_cmdline(pid),
});
}
if processes.is_empty() {
return None;
}
Some(ForegroundJob {
process_group_id: tpgid,
processes,
})
}
fn foreground_pgid(child_pid: u32) -> Option<i32> {
// /proc/<pid>/stat format: "pid (comm) state ppid pgrp session tty_nr tpgid ..."
// The (comm) field can contain spaces and parens, so we find the last ')' first.
let stat = std::fs::read_to_string(format!("/proc/{child_pid}/stat")).ok()?;
let rest = stat.get(stat.rfind(')')? + 2..)?;
let fields: Vec<&str> = rest.split_whitespace().collect();
// After (comm): state(0) ppid(1) pgrp(2) session(3) tty_nr(4) tpgid(5)
let tpgid: i32 = fields.get(5)?.parse().ok()?;
(tpgid > 0).then_some(tpgid)
}
fn process_pgrp_and_comm(pid: u32) -> Option<(i32, String)> {
let stat = std::fs::read_to_string(format!("/proc/{pid}/stat")).ok()?;
let close = stat.rfind(')')?;
let comm = stat.get(1 + stat.find('(')?..close)?.to_string();
let rest = stat.get(close + 2..)?;
let fields: Vec<&str> = rest.split_whitespace().collect();
let pgrp: i32 = fields.get(2)?.parse().ok()?;
Some((pgrp, comm))
}
fn process_cmdline(pid: u32) -> Option<String> {
let bytes = std::fs::read(format!("/proc/{pid}/cmdline")).ok()?;
if bytes.is_empty() {
return None;
}
let parts: Vec<String> = bytes
.split(|&b| b == 0)
.filter(|part| !part.is_empty())
.map(|part| String::from_utf8_lossy(part).into_owned())
.collect();
(!parts.is_empty()).then(|| parts.join(" "))
}
/// Get the current working directory of a process.
/// Uses /proc/<pid>/cwd symlink.
pub fn process_cwd(pid: u32) -> Option<PathBuf> {
if pid == 0 {
return None;
}
std::fs::read_link(format!("/proc/{pid}/cwd")).ok()
}
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