Add support for /proc/uptime

src/lib.rs

@@ -288,6 +288,9 @@ pub use locks::*;
 
 pub mod keyring;
 
+mod uptime;
+pub use uptime::*;
+
 lazy_static! {
     /// The number of clock ticks per second.
     ///

src/uptime.rs

@@ -0,0 +1,75 @@
+use crate::{FileWrapper, ProcResult};
+
+use std::io::Read;
+use std::str::FromStr;
+use std::time::Duration;
+
+/// The uptime of the system, based on the `/proc/uptime` file.
+#[derive(Debug, Clone)]
+pub struct Uptime {
+    _private: (),
+
+    /// The uptime of the system (including time spent in suspend).
+    pub uptime: f64,
+
+    /// The sum of how much time each core has spent idle.
+    pub idle: f64,
+}
+
+impl Uptime {
+    pub fn new() -> ProcResult<Uptime> {
+        let file = FileWrapper::open("/proc/uptime")?;
+        Uptime::from_reader(file)
+    }
+
+    pub fn from_reader<R: Read>(mut r: R) -> ProcResult<Uptime> {
+        let mut buf = Vec::with_capacity(128);
+        r.read_to_end(&mut buf)?;
+
+        let line = String::from_utf8_lossy(&buf);
+        let buf = line.trim();
+
+        let mut s = buf.split(' ');
+        let uptime = expect!(f64::from_str(expect!(s.next())));
+        let idle = expect!(f64::from_str(expect!(s.next())));
+
+        Ok(Uptime {
+            _private: (),
+            uptime,
+            idle,
+        })
+    }
+
+    /// The uptime of the system (including time spent in suspend).
+    pub fn uptime_duration(&self) -> Duration {
+        let secs = self.uptime.trunc() as u64;
+        let csecs = (self.uptime.fract() * 100.0).round() as u32;
+        let nsecs = csecs * 10_000_000;
+
+        Duration::new(secs, nsecs)
+    }
+
+    /// The sum of how much time each core has spent idle.
+    pub fn idle_duration(&self) -> Duration {
+        let secs = self.idle.trunc() as u64;
+        let csecs = (self.idle.fract() * 100.0).round() as u32;
+        let nsecs = csecs * 10_000_000;
+
+        Duration::new(secs, nsecs)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::io::Cursor;
+
+    #[test]
+    fn test_uptime() {
+        let reader = Cursor::new(b"2578790.61 1999230.98\n");
+        let uptime = Uptime::from_reader(reader).unwrap();
+
+        assert_eq!(uptime.uptime_duration(), Duration::new(2578790, 610_000_000));
+        assert_eq!(uptime.idle_duration(), Duration::new(1999230, 980_000_000));
+    }
+}