sysutils: basic ps utility

userspace/sysutils/Cargo.toml

@@ -133,6 +133,10 @@ path = "src/sleep.rs"
 name = "lspci"
 path = "src/lspci.rs"
 
+[[bin]]
+name = "ps"
+path = "src/ps.rs"
+
 [[bin]]
 name = "tst"
 path = "src/tst.rs"

userspace/sysutils/src/ps.rs

@@ -0,0 +1,60 @@
+use std::{fs, io, path::PathBuf, process::ExitCode};
+
+#[derive(Debug)]
+struct ProcessInfo {
+    pid: u32,
+    name: String,
+}
+
+fn list_processes() -> io::Result<Vec<u32>> {
+    let mut list = vec![];
+    for entry in fs::read_dir("/sys/proc")? {
+        let Ok(entry) = entry else {
+            continue;
+        };
+        let filename = entry.file_name();
+        let Some(name) = filename.to_str() else {
+            continue;
+        };
+        let Ok(pid) = name.parse() else {
+            continue;
+        };
+        list.push(pid);
+    }
+    Ok(list)
+}
+
+fn process_info(pid: u32) -> io::Result<ProcessInfo> {
+    let base = PathBuf::from("/sys/proc").join(format!("{pid}"));
+    let name = fs::read_to_string(base.join("name"))?;
+    Ok(ProcessInfo { pid, name })
+}
+
+fn processes() -> io::Result<Vec<ProcessInfo>> {
+    let pids = list_processes()?;
+    let processes = pids
+        .into_iter()
+        .filter_map(|pid| process_info(pid).ok())
+        .collect();
+    Ok(processes)
+}
+
+fn run() -> io::Result<()> {
+    let mut processes = processes()?;
+    processes.sort_by(|a, b| Ord::cmp(&a.pid, &b.pid));
+    println!("{:>4} NAME", "PID");
+    for process in processes {
+        println!("{:4} {}", process.pid, process.name.trim());
+    }
+    Ok(())
+}
+
+fn main() -> ExitCode {
+    match run() {
+        Ok(()) => ExitCode::SUCCESS,
+        Err(error) => {
+            eprintln!("{error}");
+            ExitCode::FAILURE
+        }
+    }
+}

xtask/src/build/userspace.rs

@@ -48,6 +48,7 @@ const PROGRAMS: &[(&str, &str)] = &[
     ("sync", "bin/sync"),
     ("sleep", "bin/sleep"),
     ("lspci", "bin/lspci"),
+    ("ps", "bin/ps"),
     ("tst", "bin/tst"),
     // netutils
     ("netconf", "sbin/netconf"),