3 files changed, 84 insertions, 0 deletions
diff --git a/waybar-record/Cargo.lock b/waybar-record/Cargo.lock
new file mode 100644
index 0000000..58bfb49
--- /dev/null
+++ b/waybar-record/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "waybar-record"
+version = "0.1.0"
diff --git a/waybar-record/Cargo.toml b/waybar-record/Cargo.toml
new file mode 100644
index 0000000..bff82f5
--- /dev/null
+++ b/waybar-record/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "waybar-record"
+version = "0.1.0"
+edition = "2024"
+
+# Make the binary small
+[profile.release]
+opt-level = "z"
+lto = true
+strip = true
+panic = "abort"
diff --git a/waybar-record/src/main.rs b/waybar-record/src/main.rs
new file mode 100644
index 0000000..8ceb6c7
--- /dev/null
+++ b/waybar-record/src/main.rs
@@ -0,0 +1,66 @@
+use std::fs;
+use std::io::{Read, Write};
+use std::time::Duration;
+
+const TARGET: &str = "gpu-screen-recorder";
+const POLL_INTERVAL: Duration = Duration::from_secs(2);
+
+/// Scans /proc for a process whose argv[0] basename matches the target.
+/// Reads cmdline (not the truncated `comm`) to avoid false positives
+/// from the 15-char comm truncation matching an unrelated binary.
+fn is_recording() -> bool {
+    let entries = match fs::read_dir("/proc") {
+        Ok(d) => d,
+        Err(_) => return false,
+    };
+
+    for entry in entries.flatten() {
+        let name = entry.file_name();
+        let Some(pid_str) = name.to_str() else {
+            continue;
+        };
+        if !pid_str.bytes().all(|b| b.is_ascii_digit()) {
+            continue;
+        }
+
+        let mut buf = Vec::with_capacity(64);
+        if fs::File::open(format!("/proc/{pid_str}/cmdline"))
+            .and_then(|mut f| f.read_to_end(&mut buf))
+            .is_err()
+        {
+            continue;
+        }
+
+        // cmdline is NUL-separated; argv[0] is everything before the first NUL
+        let argv0 = buf.split(|&b| b == 0).next().unwrap_or(&[]);
+        let argv0 = String::from_utf8_lossy(argv0);
+        let basename = argv0.rsplit('/').next().unwrap_or(&argv0);
+
+        if basename == TARGET {
+            return true;
+        }
+    }
+    false
+}
+
+fn emit(recording: bool) {
+    let json = if recording {
+        r#"{"text":"󰑊 <span color='#aaaaaa'>Recording</span>","class":"recording","alt":"recording","tooltip":"gpu-screen-recorder is running"}"#
+    } else {
+        r#"{"text":"","class":"idle","alt":"idle","tooltip":""}"#
+    };
+    println!("{json}");
+    let _ = std::io::stdout().flush();
+}
+
+fn main() {
+    let mut last: Option<bool> = None;
+    loop {
+        let now = is_recording();
+        if last != Some(now) {
+            emit(now);
+            last = Some(now);
+        }
+        std::thread::sleep(POLL_INTERVAL);
+    }
+}