From 480435ff68a910eabc011e44f5a63b43536a4d02 Mon Sep 17 00:00:00 2001
From: Philipp Gesang <phg@phi-gamma.net>
Date: Wed, 8 Dec 2021 19:07:54 +0100
Subject: add ioctl wrappers for KDGETLED / KDSETLED

---
 src/lib.rs | 124 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 119 insertions(+), 5 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index c652565..681177c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -46,17 +46,19 @@ fn cvt_r<T: IsMinusOne>(f: &mut dyn FnMut() -> T) -> io::Result<T>
 /** Wrappers for ``ioctl_console(2)`` functionality. */
 pub mod ioctl
 {
-    use super::{cvt_r, Palette};
+    use super::{cvt_r, KbLedState, Palette};
     use libc::ioctl;
-    use std::{io, os::unix::io::AsRawFd};
+    use std::{io::Result, os::unix::io::AsRawFd};
 
     /* XXX: can we get these into ``libc``? */
     pub const KDGKBTYPE: libc::c_ulong = 0x4b33; /* kd.h */
     pub const GIO_CMAP: libc::c_ulong = 0x00004B70; /* kd.h */
     pub const PIO_CMAP: libc::c_ulong = 0x00004B71; /* kd.h */
     pub const KB_101: libc::c_char = 0x0002; /* kd.h */
+    pub const KDGETLED: libc::c_ulong = 0x4b31; /* kd.h */
+    pub const KDSETLED: libc::c_ulong = 0x4b32; /* kd.h */
 
-    pub fn kdgkbtype<F: AsRawFd>(fd: &F) -> io::Result<libc::c_char>
+    pub fn kdgkbtype<F: AsRawFd>(fd: &F) -> Result<libc::c_char>
     {
         let mut kb: libc::c_char = 0;
 
@@ -67,7 +69,7 @@ pub mod ioctl
         Ok(kb)
     }
 
-    pub fn pio_cmap<F: AsRawFd>(fd: &F, pal: &Palette) -> io::Result<()>
+    pub fn pio_cmap<F: AsRawFd>(fd: &F, pal: &Palette) -> Result<()>
     {
         /* cvt_r because technically it can’t be ruled out that we hit EINTR. */
         cvt_r(&mut || {
@@ -82,7 +84,7 @@ pub mod ioctl
         .map(|_| ())
     }
 
-    pub fn gio_cmap<F: AsRawFd>(fd: &F) -> io::Result<Palette>
+    pub fn gio_cmap<F: AsRawFd>(fd: &F) -> Result<Palette>
     {
         let mut pal = Palette::new();
 
@@ -101,6 +103,118 @@ pub mod ioctl
         .map(|_| ())?;
         Ok(pal)
     }
+
+    pub fn kdgetled<F: AsRawFd>(fd: &F) -> Result<KbLedState>
+    {
+        let mut leds: libc::c_char = 0;
+
+        cvt_r(&mut || {
+            unsafe {
+                ioctl(
+                    fd.as_raw_fd(),
+                    KDGETLED,
+                    std::mem::transmute::<&mut libc::c_char, *mut libc::c_void>(
+                        &mut leds,
+                    ),
+                )
+            }
+        })
+        .map(|_| ())?;
+
+        Ok(KbLedState::from(leds))
+    }
+
+    /** If ``state`` is ``None`` it is taken to mean “revert to normal” as per
+    the man page:
+
+        KDSETLED
+            Set the LEDs. The LEDs are set to correspond to the lower three
+            bits of the unsigned long integer in argp. However, if a higher
+            order bit is set, the LEDs revert to normal: displaying the state
+            of the keyboard functions of caps lock, num lock, and scroll lock.
+    */
+
+    pub fn kdsetled<F: AsRawFd>(fd: &F, state: Option<KbLedState>)
+        -> Result<()>
+    {
+        let leds: libc::c_char = if let Some(state) = state {
+            state.into()
+        } else {
+            libc::c_char::MAX
+        };
+
+        cvt_r(&mut || {
+            unsafe {
+                ioctl(
+                    fd.as_raw_fd(),
+                    KDSETLED,
+                    std::mem::transmute::<&libc::c_char, *const libc::c_void>(
+                        &leds,
+                    ),
+                )
+            }
+        })
+        .map(|_| ())?;
+
+        Ok(())
+    }
+}
+
+#[derive(Debug)]
+pub struct KbLedState(u8);
+
+impl KbLedState
+{
+    fn new(cap: bool, num: bool, scr: bool) -> Self
+    {
+        let mut state = 0u8;
+
+        state |= (cap as u8) << 2;
+        state |= (num as u8) << 1;
+        state |= scr as u8;
+
+        Self(state)
+    }
+}
+
+impl From<libc::c_char> for KbLedState
+{
+    fn from(leds: libc::c_char) -> Self
+    {
+        Self::new(leds & 0x4 != 0, leds & 0x2 != 0, leds & 0x1 != 0)
+    }
+}
+
+impl From<KbLedState> for libc::c_char
+{
+    fn from(state: KbLedState) -> Self { state.0 as libc::c_char }
+}
+
+impl From<KbLedState> for u8
+{
+    fn from(state: KbLedState) -> Self { state.0 }
+}
+
+#[cfg(test)]
+mod kb_led_state
+{
+    use super::KbLedState;
+
+    #[test]
+    fn create()
+    {
+        assert_eq!(0u8, KbLedState::new(false, false, false).into());
+        assert_eq!(1u8, KbLedState::new(false, false, true).into());
+        assert_eq!(2u8, KbLedState::new(false, true, false).into());
+        assert_eq!(4u8, KbLedState::new(true, false, false).into());
+        assert_eq!(6u8, KbLedState::new(true, true, false).into());
+
+        assert_eq!(0u8, KbLedState::from(0u8 as libc::c_char).into());
+        assert_eq!(1u8, KbLedState::from(1u8 as libc::c_char).into());
+        assert_eq!(2u8, KbLedState::from(2u8 as libc::c_char).into());
+        assert_eq!(4u8, KbLedState::from(4u8 as libc::c_char).into());
+        assert_eq!(6u8, KbLedState::from(6u8 as libc::c_char).into());
+    }
 }
 
 #[derive(Debug)]
-- 
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