Add battery readout

Cargo.lock

@@ -12,6 +12,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 name = "rwmstatus"
 version = "0.1.0"
 dependencies = [
+ "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
  "x11 2.18.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 

Cargo.toml

@@ -8,3 +8,4 @@ build = "build.rs"
 
 [dependencies]
 x11 = "2"
+libc = "0.2"

src/main.rs

@@ -1,14 +1,130 @@
+//! # rwmstatus
+//!
+//! Status monitor bar for the dwm/rwm window manager (or any WM which uses
+//! WM_NAME of the X11 root window as its status bar).  It is a direct port of
+//! [dwmstatus](https://dwm.suckless.org/status_monitor/) to Rust.
+//!
+//! This is part of a larger project to port various
+//! [suckless.org](https://suckless.org/) programs to Rust, a programming
+//! language that sucks less.
+
 extern crate x11;
+extern crate libc;
 
-use x11::xlib::Display;
-use x11::xlib::{XDefaultRootWindow, XOpenDisplay, XStoreName, XSync};
-
-use std::ptr;
+// std module imports
+use std::io;
+use std::io::prelude::*;
 use std::process;
+use std::ptr;
 use std::thread;
 use std::time;
 
+// std type imports
 use std::ffi::CString;
+use std::fs::File;
+
+// x11 imports
+use x11::xlib::Display;
+use x11::xlib::{XDefaultRootWindow, XOpenDisplay, XStoreName, XSync};
+
+/// Convert a Rust string to a CString and panic if it fails.
+#[inline]
+fn cstring(string: &str) -> CString {
+    CString::new(string).expect(&format!("CString::new({}) failed.", string))
+}
+
+/// Read the contents of the file base/filename and return as a String.
+#[inline]
+fn read_file(base: &str, filename: &str) -> io::Result<String> {
+    let mut file = File::open([base, filename].join("/"))?;
+    let mut contents = String::new();
+    file.read_to_string(&mut contents)?;
+    Ok(contents)
+}
+
+/// Return the three load average values.
+fn get_load_avgs() -> String {
+    let mut avgs: [libc::c_double; 3] = [0.0; 3];
+
+    let rc: libc::c_int;
+    unsafe {
+        rc = libc::getloadavg(&mut avgs[0] as *mut libc::c_double, 3);
+    }
+
+    if rc < 0 {
+        return format!("");
+    }
+
+    format!("{:.2} {:.2} {:.2}", avgs[0], avgs[1], avgs[2])
+}
+
+const BATT_PATH: &'static str = "/sys/class/power_supply";
+const BATTS: [&'static str; 2] = ["BAT0", "BAT1"];
+
+/// Return battery status for all batteries.
+fn get_batteries() -> String {
+    let mut batt_strs: Vec<String> = vec![];
+
+    for batt in BATTS.iter() {
+        batt_strs.push(get_battery(&[BATT_PATH, batt].join("/")));
+    }
+
+    batt_strs.join("|")
+}
+
+/// Return battery status for the battery at the provided path.
+fn get_battery(batt_base: &str) -> String {
+    match read_file(&batt_base, "present") {
+        Ok(contents) => {
+            if !contents.starts_with('1') {
+                return format!("not present");
+            }
+        }
+        Err(_) => return format!(""),
+    };
+
+    let co = match read_file(&batt_base, "charge_full_design") {
+        Ok(contents) => contents,
+        Err(_) => {
+            match read_file(&batt_base, "energy_full_design") {
+                Ok(contents) => contents,
+                Err(_) => return format!(""),
+            }
+        }
+    };
+
+    let desired_capacity: u64 = co.trim().parse().expect(&format!("Not a number: {}", co));
+
+    let co = match read_file(&batt_base, "charge_now") {
+        Ok(contents) => contents,
+        Err(_) => {
+            match read_file(&batt_base, "energy_now") {
+                Ok(contents) => contents,
+                Err(_) => return format!(""),
+            }
+        }
+    };
+
+    let remaining_capacity: u64 = co.trim().parse().expect(&format!("Invalid number: {}", co));
+
+    let status: char = match read_file(&batt_base, "status") {
+        Ok(contents) => {
+            match &contents.trim()[..] {
+                "Full" => 'F',
+                "Discharging" => '-',
+                "Charging" => '+',
+                _ => '?',
+            }
+        }
+        Err(_) => '?',
+    };
+
+    format!(
+        "{:.0}%{}",
+        ((remaining_capacity as f64) / (desired_capacity as f64)) * 100.0,
+        status
+    )
+}
 
 fn main() {
     let display: *mut Display;
@@ -23,13 +139,15 @@ fn main() {
     }
 
     loop {
-        let status = CString::new("Hello!").expect("CString::new failed when setting status.");
+        let avgs = get_load_avgs();
+        let batts = get_batteries();
 
+        let status = cstring(&format!("L:{} B:{}", avgs, batts));
         unsafe {
             XStoreName(display, XDefaultRootWindow(display), status.as_ptr());
             XSync(display, false as i32);
         }
 
-        thread::sleep(time::Duration::from_secs(1));
+        thread::sleep(time::Duration::from_secs(60));
     }
 }