Make sure we check the ioctl term size result

src/main.rs

@@ -4,6 +4,7 @@
 
 #![warn(trivial_casts, trivial_numeric_casts)]
 #![warn(unused_extern_crates, unused_qualifications)]
+#![warn(unused_results)]
 
 extern crate ansi_term;
 extern crate datetime;

src/options.rs

@@ -28,6 +28,7 @@ pub struct Options {
 impl Options {
 
     /// Call getopts on the given slice of command-line strings.
+    #[allow(unused_results)]
     pub fn getopts(args: &[String]) -> Result<(Options, Vec<String>), Misfire> {
         let mut opts = getopts::Options::new();
         opts.optflag("1", "oneline",   "display one entry per line");

src/term.rs

@@ -1,39 +1,53 @@
-mod c {
-    use std::mem::zeroed;
-    use libc::{c_int, c_ushort, c_ulong, STDOUT_FILENO};
+//! System calls for getting the terminal size.
+//!
+//! Getting the terminal size is performed using an ioctl command that takes
+//! the file handle to the terminal -- which in this case, is stdout -- and
+//! populates a structure containing the values.
+//!
+//! The size is needed when the user wants the output formatted into columns:
+//! the default grid view, or the hybrid grid-details view.
+
+use std::mem::zeroed;
+use libc::{c_int, c_ushort, c_ulong, STDOUT_FILENO};
+
+
+/// The number of rows and columns of a terminal.
+struct Winsize {
+    ws_row: c_ushort,
+    ws_col: c_ushort,
+}
 
-    // Getting the terminal size is done using an ioctl command that
-    // takes the file handle to the terminal (which in our case is
-    // stdout), and populates a structure with the values.
+// Unfortunately the actual command is not standardised...
 
-    pub struct Winsize {
-        pub ws_row: c_ushort,
-        pub ws_col: c_ushort,
-    }
+#[cfg(any(target_os = "linux", target_os = "android"))]
+static TIOCGWINSZ: c_ulong = 0x5413;
 
-    // Unfortunately the actual command is not standardised...
+#[cfg(any(target_os = "macos", target_os = "ios", target_os = "dragonfly"))]
+static TIOCGWINSZ: c_ulong = 0x40087468;
 
-    #[cfg(any(target_os = "linux", target_os = "android"))]
-    static TIOCGWINSZ: c_ulong = 0x5413;
+extern {
+    pub fn ioctl(fd: c_int, request: c_ulong, ...) -> c_int;
+}
 
-    #[cfg(any(target_os = "macos", target_os = "ios", target_os = "dragonfly"))]
-    static TIOCGWINSZ: c_ulong = 0x40087468;
+/// Runs the ioctl command. Returns (0, 0) if output is not to a terminal, or
+/// there is an error. (0, 0) is an invalid size to have anyway, which is why
+/// it can be used as a nil value.
+unsafe fn get_dimensions() -> Winsize {
+    let mut window: Winsize = zeroed();
+    let result = ioctl(STDOUT_FILENO, TIOCGWINSZ, &mut window);
 
-    extern {
-        pub fn ioctl(fd: c_int, request: c_ulong, ...) -> c_int;
+    if result == -1 {
+        zeroed()
     }
-
-    pub unsafe fn dimensions() -> Winsize {
-        let mut window: Winsize = zeroed();
-        ioctl(STDOUT_FILENO, TIOCGWINSZ, &mut window);
+    else {
         window
     }
 }
 
 /// Query the current processes's output, returning its width and height as a
-/// number of characters. Returns None if the output isn't to a terminal.
+/// number of characters. Returns `None` if the output isn't to a terminal.
 pub fn dimensions() -> Option<(usize, usize)> {
-    let w = unsafe { c::dimensions() };
+    let w = unsafe { get_dimensions() };
 
     if w.ws_col == 0 || w.ws_row == 0 {
         None