Add support for virtual uinput devices (#37)

* Prototype support for virtual uinput devices

* Tidy uinput a bit

* Have all the evtest examples use the same args/prompt code

* Switch to libc uinput* structs

* Use InputId in uinput, use libc _CNT constants

* Don't use align_to_mut

* Only check /dev/input/eventN files

* Spelling fixup

* Fix compilation error

* Ah, there we go. Much better.

Co-authored-by: Jeff Hiner <jeff-hiner@users.noreply.github.com>
Co-authored-by: Noah <33094578+coolreader18@users.noreply.github.com>

Cargo.toml

@@ -12,7 +12,7 @@ edition = "2018"
 tokio = ["tokio_1", "futures-core"]
 
 [dependencies]
-libc = "0.2.22"
+libc = "0.2.89"
 bitvec = "0.21"
 nix = "0.19.0"
 

examples/_pick_device.rs

@@ -0,0 +1,28 @@
+//! An arg parser/prompt shared between the `evtest*` examples. Also demonstrates opening/finding
+//! connected devices.
+
+use std::io::prelude::*;
+
+pub fn pick_device() -> evdev::Device {
+    let mut args = std::env::args_os();
+    args.next();
+    if let Some(dev_file) = args.next() {
+        evdev::Device::open(dev_file).unwrap()
+    } else {
+        let mut devices = evdev::enumerate().collect::<Vec<_>>();
+        // readdir returns them in reverse order from their eventN names for some reason
+        devices.reverse();
+        for (i, d) in devices.iter().enumerate() {
+            println!("{}: {}", i, d.name().unwrap_or("Unnamed device"));
+        }
+        print!("Select the device [0-{}]: ", devices.len());
+        let _ = std::io::stdout().flush();
+        let mut chosen = String::new();
+        std::io::stdin().read_line(&mut chosen).unwrap();
+        let n = chosen.trim().parse::<usize>().unwrap();
+        devices.into_iter().nth(n).unwrap()
+    }
+}
+
+#[allow(dead_code)]
+fn main() {}

examples/evtest.rs

@@ -1,23 +1,10 @@
-// Similar to the evtest tool.
+//! Similar to the evtest tool.
 
-use std::io::prelude::*;
+// cli/"tui" shared between the evtest examples
+mod _pick_device;
 
 fn main() {
-    let mut args = std::env::args_os();
-    let mut d = if args.len() > 1 {
-        evdev::Device::open(&args.nth(1).unwrap()).unwrap()
-    } else {
-        let devices = evdev::enumerate().collect::<Vec<_>>();
-        for (i, d) in devices.iter().enumerate() {
-            println!("{}: {}", i, d.name().unwrap_or("Unnamed device"));
-        }
-        print!("Select the device [0-{}]: ", devices.len());
-        let _ = std::io::stdout().flush();
-        let mut chosen = String::new();
-        std::io::stdin().read_line(&mut chosen).unwrap();
-        let n = chosen.trim().parse::<usize>().unwrap();
-        devices.into_iter().nth(n).unwrap()
-    };
+    let mut d = _pick_device::pick_device();
     println!("{}", d);
     println!("Events:");
     loop {

examples/evtest_nonblocking.rs

@@ -9,24 +9,13 @@ use nix::{
     fcntl::{FcntlArg, OFlag},
     sys::epoll,
 };
-use std::io::prelude::*;
 use std::os::unix::io::{AsRawFd, RawFd};
 
+// cli/"tui" shared between the evtest examples
+mod _pick_device;
+
 fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let mut args = std::env::args_os();
-    let mut d = if args.len() > 1 {
-        evdev::Device::open(&args.nth(1).unwrap()).unwrap()
-    } else {
-        let mut devices = evdev::enumerate().collect::<Vec<_>>();
-        for (i, d) in devices.iter().enumerate() {
-            println!("{}: {}", i, d.name().unwrap_or("Unnamed device"));
-        }
-        print!("Select the device [0-{}]: ", devices.len());
-        let _ = std::io::stdout().flush();
-        let mut chosen = String::new();
-        std::io::stdin().read_line(&mut chosen).unwrap();
-        devices.swap_remove(chosen.trim().parse::<usize>().unwrap())
-    };
+    let mut d = _pick_device::pick_device();
     println!("{}", d);
 
     let raw_fd = d.as_raw_fd();

examples/evtest_tokio.rs

@@ -1,21 +1,13 @@
+//! Demonstrating how to monitor events with evdev + tokio
+
 use tokio_1 as tokio;
 
+// cli/"tui" shared between the evtest examples
+mod _pick_device;
+
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let mut args = std::env::args_os();
-    let d = if args.len() > 1 {
-        evdev::Device::open(&args.nth(1).unwrap())?
-    } else {
-        let mut devices = evdev::enumerate().collect::<Vec<_>>();
-        for (i, d) in devices.iter().enumerate() {
-            println!("{}: {}", i, d.name().unwrap_or("Unnamed device"));
-        }
-        print!("Select the device [0-{}]: ", devices.len());
-        let _ = std::io::Write::flush(&mut std::io::stdout());
-        let mut chosen = String::new();
-        std::io::stdin().read_line(&mut chosen)?;
-        devices.swap_remove(chosen.trim().parse::<usize>()?)
-    };
+    let d = _pick_device::pick_device();
     println!("{}", d);
     println!("Events:");
     let mut events = d.into_event_stream()?;

examples/virtual_keyboard.rs

@@ -0,0 +1,35 @@
+// Create a virtual keyboard, just while this is running.
+// Generally this requires root.
+
+use evdev::{uinput::VirtualDeviceBuilder, AttributeSet, EventType, InputEvent, Key};
+use std::thread::sleep;
+use std::time::Duration;
+
+fn main() -> std::io::Result<()> {
+    let mut keys = AttributeSet::<Key>::new();
+    keys.insert(Key::BTN_DPAD_UP);
+
+    let mut device = VirtualDeviceBuilder::new()?
+        .name("Fake Keyboard")
+        .with_keys(&keys)?
+        .build()
+        .unwrap();
+
+    let type_ = EventType::KEY;
+    // Note this will ACTUALLY PRESS the button on your computer.
+    // Hopefully you don't have BTN_DPAD_UP bound to anything important.
+    let code = Key::BTN_DPAD_UP.code();
+
+    println!("Waiting for Ctrl-C...");
+    loop {
+        let down_event = InputEvent::new(type_, code, 1);
+        device.emit(&[down_event]).unwrap();
+        println!("Pressed.");
+        sleep(Duration::from_secs(2));
+
+        let up_event = InputEvent::new(type_, code, 0);
+        device.emit(&[up_event]).unwrap();
+        println!("Released.");
+        sleep(Duration::from_secs(2));
+    }
+}

src/constants.rs

@@ -43,7 +43,7 @@ evdev_enum!(
 );
 
 impl EventType {
-    pub(crate) const COUNT: usize = 0x20;
+    pub(crate) const COUNT: usize = libc::EV_CNT;
 }
 
 /// A "synchronization" message type published by the kernel into the events stream.
@@ -87,7 +87,7 @@ evdev_enum!(
 );
 
 impl PropType {
-    pub(crate) const COUNT: usize = 0x20;
+    pub(crate) const COUNT: usize = libc::INPUT_PROP_CNT;
 }
 
 /// A type of relative axis measurement, typically produced by mice.
@@ -113,7 +113,7 @@ evdev_enum!(
 );
 
 impl RelativeAxisType {
-    pub(crate) const COUNT: usize = 0x10;
+    pub(crate) const COUNT: usize = libc::REL_CNT;
 }
 
 /// A type of absolute axis measurement, typically used for touch events and joysticks.
@@ -182,7 +182,7 @@ evdev_enum!(
 );
 
 impl AbsoluteAxisType {
-    pub(crate) const COUNT: usize = 0x40;
+    pub(crate) const COUNT: usize = libc::ABS_CNT;
 }
 
 /// An event type corresponding to a physical or virtual switch.
@@ -229,7 +229,7 @@ evdev_enum!(
 );
 
 impl SwitchType {
-    pub(crate) const COUNT: usize = 0x11;
+    pub(crate) const COUNT: usize = libc::SW_CNT;
 }
 
 /// LEDs specified by USB HID.
@@ -257,7 +257,7 @@ evdev_enum!(
 );
 
 impl LedType {
-    pub(crate) const COUNT: usize = 0x10;
+    pub(crate) const COUNT: usize = libc::LED_CNT;
 }
 
 /// Various miscellaneous event types.
@@ -282,7 +282,7 @@ evdev_enum!(
 );
 
 impl MiscType {
-    pub(crate) const COUNT: usize = 0x08;
+    pub(crate) const COUNT: usize = libc::MSC_CNT;
 }
 
 // pub enum FFStatusDataIndex {
@@ -312,7 +312,7 @@ impl MiscType {
 
 // impl FFEffect {
 //     // Needs to be a multiple of 8
-//     pub const COUNT: usize = 0x80;
+//     pub const COUNT: usize = libc::FF_CNT;
 // }
 
 // #[derive(Copy, Clone, PartialEq, Eq)]
@@ -321,7 +321,7 @@ impl MiscType {
 // evdev_enum!(RepeatType, REP_DELAY = 0x00, REP_PERIOD = 0x01,);
 
 // impl RepeatType {
-//     pub(crate) const COUNT: usize = 0x02;
+//     pub(crate) const COUNT: usize = libc::REP_CNT;
 // }
 
 /// A type associated with simple sounds, such as beeps or tones.
@@ -337,5 +337,5 @@ evdev_enum!(
 );
 
 impl SoundType {
-    pub(crate) const COUNT: usize = 0x08;
+    pub(crate) const COUNT: usize = libc::SND_CNT;
 }

src/inputid.rs

@@ -2,7 +2,7 @@ use std::fmt;
 
 #[derive(Clone)]
 #[repr(transparent)]
-pub struct InputId(libc::input_id);
+pub struct InputId(pub(crate) libc::input_id);
 
 impl From<libc::input_id> for InputId {
     #[inline]
@@ -30,6 +30,16 @@ impl InputId {
     pub fn version(&self) -> u16 {
         self.0.version
     }
+
+    /// Crate a new InputId, useful for customizing virtual input devices.
+    pub fn new(bus_type: BusType, vendor: u16, product: u16, version: u16) -> Self {
+        Self::from(libc::input_id {
+            bustype: bus_type.0,
+            vendor,
+            product,
+            version,
+        })
+    }
 }
 
 impl fmt::Debug for InputId {

src/lib.rs

@@ -67,8 +67,8 @@
 //! For demonstrations of how to use this library in blocking, nonblocking, and async (tokio) modes,
 //! please reference the "examples" directory.
 
-#![cfg(any(unix, target_os = "android"))]
-#![allow(non_camel_case_types)]
+// should really be cfg(target_os = "linux") and maybe also android?
+#![cfg(unix)]
 
 // has to be first for its macro
 #[macro_use]
@@ -81,10 +81,12 @@ pub mod raw_stream;
 mod scancodes;
 mod sync_stream;
 mod sys;
+pub mod uinput;
 
 #[cfg(feature = "tokio")]
 mod tokio_stream;
 
+use std::os::unix::ffi::OsStrExt;
 use std::time::{Duration, SystemTime};
 use std::{fmt, io};
 
@@ -123,6 +125,7 @@ pub enum InputEventKind {
 /// - `value: s32`
 ///
 /// The meaning of the "code" and "value" fields will depend on the underlying type of event.
+#[derive(Copy, Clone)]
 #[repr(transparent)]
 pub struct InputEvent(libc::input_event);
 
@@ -174,6 +177,34 @@ impl InputEvent {
     pub fn value(&self) -> i32 {
         self.0.value
     }
+
+    /// Create a new InputEvent. Only really useful for emitting events on virtual devices.
+    pub fn new(type_: EventType, code: u16, value: i32) -> Self {
+        InputEvent(libc::input_event {
+            time: libc::timeval {
+                tv_sec: 0,
+                tv_usec: 0,
+            },
+            type_: type_.0,
+            code,
+            value,
+        })
+    }
+
+    /// Create a new InputEvent with the time field set to "now" on the system clock.
+    ///
+    /// Note that this isn't usually necessary simply for emitting events on a virtual device, as
+    /// even though [`InputEvent::new`] creates an `input_event` with the time field as zero,
+    /// the kernel will update `input_event.time` when it emits the events to any programs reading
+    /// the event "file".
+    pub fn new_now(type_: EventType, code: u16, value: i32) -> Self {
+        InputEvent(libc::input_event {
+            time: systime_to_timeval(&SystemTime::now()),
+            type_: type_.0,
+            code,
+            value,
+        })
+    }
 }
 
 impl From<libc::input_event> for InputEvent {
@@ -223,12 +254,16 @@ impl Iterator for EnumerateDevices {
         let readdir = self.readdir.as_mut()?;
         loop {
             if let Ok(entry) = readdir.next()? {
-                if let Ok(dev) = Device::open(entry.path()) {
+                let path = entry.path();
+                let fname = path.file_name().unwrap();
+                if fname.as_bytes().starts_with(b"event") {
+                    if let Ok(dev) = Device::open(&path) {
                         return Some(dev);
                     }
                 }
             }
         }
+    }
 }
 
 /// A safe Rust version of clock_gettime against CLOCK_REALTIME
@@ -263,24 +298,7 @@ pub(crate) fn nix_err(err: nix::Error) -> io::Error {
     }
 }
 
-#[cfg(test)]
-mod test {
-    use std::mem::MaybeUninit;
-
-    #[test]
-    fn align_to_mut_is_sane() {
-        // We assume align_to_mut -> u8 puts everything in inner. Let's double check.
-        let mut bits: u32 = 0;
-        let (prefix, inner, suffix) =
-            unsafe { std::slice::from_mut(&mut bits).align_to_mut::<u8>() };
-        assert_eq!(prefix.len(), 0);
-        assert_eq!(inner.len(), std::mem::size_of::<u32>());
-        assert_eq!(suffix.len(), 0);
-
-        let mut ev: MaybeUninit<libc::input_event> = MaybeUninit::uninit();
-        let (prefix, inner, suffix) = unsafe { std::slice::from_mut(&mut ev).align_to_mut::<u8>() };
-        assert_eq!(prefix.len(), 0);
-        assert_eq!(inner.len(), std::mem::size_of::<libc::input_event>());
-        assert_eq!(suffix.len(), 0);
-    }
+/// SAFETY: T must not have any padding or otherwise uninitialized bytes inside of it
+pub(crate) unsafe fn cast_to_bytes<T: ?Sized>(mem: &T) -> &[u8] {
+    std::slice::from_raw_parts(mem as *const T as *const u8, std::mem::size_of_val(mem))
 }

src/raw_stream.rs

@@ -382,10 +382,10 @@ impl RawDevice {
 
         // TODO: use Vec::spare_capacity_mut or Vec::split_at_spare_mut when they stabilize
         let spare_capacity = vec_spare_capacity_mut(&mut self.event_buf);
-        let (_, uninit_buf, _) = unsafe { spare_capacity.align_to_mut::<mem::MaybeUninit<u8>>() };
+        let spare_capacity_size = std::mem::size_of_val(spare_capacity);
 
         // use libc::read instead of nix::unistd::read b/c we need to pass an uninitialized buf
-        let res = unsafe { libc::read(fd, uninit_buf.as_mut_ptr() as _, uninit_buf.len()) };
+        let res = unsafe { libc::read(fd, spare_capacity.as_mut_ptr() as _, spare_capacity_size) };
         let bytes_read = nix::errno::Errno::result(res).map_err(nix_err)?;
         let num_read = bytes_read as usize / mem::size_of::<libc::input_event>();
         unsafe {

src/scancodes.rs

@@ -16,7 +16,7 @@ impl Key {
         self.0
     }
 
-    pub(crate) const COUNT: usize = 0x300;
+    pub(crate) const COUNT: usize = libc::KEY_CNT;
 }
 
 const fn bit_elts<T>(bits: usize) -> usize {

src/sys.rs

@@ -1,12 +1,12 @@
 use libc::c_int;
-use libc::{ff_effect, input_absinfo, input_id};
+use libc::{ff_effect, input_absinfo, input_id, uinput_setup};
 // use libc::{
 //     ff_condition_effect, ff_constant_effect, ff_envelope, ff_periodic_effect, ff_ramp_effect,
 //     ff_replay, ff_rumble_effect, ff_trigger, input_event, input_keymap_entry,
 // };
 use nix::{
-    convert_ioctl_res, ioctl_read, ioctl_read_buf, ioctl_write_int, ioctl_write_ptr,
-    request_code_read,
+    convert_ioctl_res, ioctl_none, ioctl_read, ioctl_read_buf, ioctl_write_buf, ioctl_write_int,
+    ioctl_write_ptr, request_code_read,
 };
 
 ioctl_read!(eviocgeffects, b'E', 0x84, ::libc::c_int);
@@ -36,6 +36,22 @@ ioctl_write_int!(eviocgrab, b'E', 0x90);
 ioctl_write_int!(eviocrevoke, b'E', 0x91);
 ioctl_write_int!(eviocsclockid, b'E', 0xa0);
 
+const UINPUT_IOCTL_BASE: u8 = b'U';
+ioctl_write_ptr!(ui_dev_setup, UINPUT_IOCTL_BASE, 3, uinput_setup);
+ioctl_none!(ui_dev_create, UINPUT_IOCTL_BASE, 1);
+
+ioctl_write_int!(ui_set_evbit, UINPUT_IOCTL_BASE, 100);
+ioctl_write_int!(ui_set_keybit, UINPUT_IOCTL_BASE, 101);
+ioctl_write_int!(ui_set_relbit, UINPUT_IOCTL_BASE, 102);
+ioctl_write_int!(ui_set_absbit, UINPUT_IOCTL_BASE, 103);
+ioctl_write_int!(ui_set_mscbit, UINPUT_IOCTL_BASE, 104);
+ioctl_write_int!(ui_set_ledbit, UINPUT_IOCTL_BASE, 105);
+ioctl_write_int!(ui_set_sndbit, UINPUT_IOCTL_BASE, 106);
+ioctl_write_int!(ui_set_ffbit, UINPUT_IOCTL_BASE, 107);
+ioctl_write_buf!(ui_set_phys, UINPUT_IOCTL_BASE, 108, u8);
+ioctl_write_int!(ui_set_swbit, UINPUT_IOCTL_BASE, 109);
+ioctl_write_int!(ui_set_propbit, UINPUT_IOCTL_BASE, 110);
+
 macro_rules! eviocgbit_ioctl {
     ($mac:ident!($name:ident, $ev:ident, $ty:ty)) => {
         eviocgbit_ioctl!($mac!($name, $crate::EventType::$ev.0, $ty));

src/uinput.rs

@@ -0,0 +1,156 @@
+//! Virtual device emulation for evdev via uinput.
+//!
+//! This is quite useful when testing/debugging devices, or synchronization.
+
+use crate::constants::EventType;
+use crate::inputid::{BusType, InputId};
+use crate::{nix_err, sys, AttributeSetRef, InputEvent, Key, RelativeAxisType};
+use libc::O_NONBLOCK;
+use std::fs::{File, OpenOptions};
+use std::io::{self, Write};
+use std::os::unix::{fs::OpenOptionsExt, io::AsRawFd};
+
+const UINPUT_PATH: &str = "/dev/uinput";
+
+#[derive(Debug)]
+pub struct VirtualDeviceBuilder<'a> {
+    file: File,
+    name: &'a [u8],
+    id: Option<libc::input_id>,
+}
+
+impl<'a> VirtualDeviceBuilder<'a> {
+    pub fn new() -> io::Result<Self> {
+        let mut options = OpenOptions::new();
+
+        // Open in write-only, in nonblocking mode.
+        let file = options
+            .write(true)
+            .custom_flags(O_NONBLOCK)
+            .open(UINPUT_PATH)?;
+
+        Ok(VirtualDeviceBuilder {
+            file,
+            name: Default::default(),
+            id: None,
+        })
+    }
+
+    #[inline]
+    pub fn name<S: AsRef<[u8]> + ?Sized>(mut self, name: &'a S) -> Self {
+        self.name = name.as_ref();
+        self
+    }
+
+    #[inline]
+    pub fn input_id(mut self, id: InputId) -> Self {
+        self.id = Some(id.0);
+        self
+    }
+
+    pub fn with_keys(self, keys: &AttributeSetRef<Key>) -> io::Result<Self> {
+        // Run ioctls for setting capability bits
+        unsafe {
+            sys::ui_set_evbit(
+                self.file.as_raw_fd(),
+                crate::EventType::KEY.0 as nix::sys::ioctl::ioctl_param_type,
+            )
+        }
+        .map_err(nix_err)?;
+
+        for bit in keys.iter() {
+            unsafe {
+                sys::ui_set_keybit(
+                    self.file.as_raw_fd(),
+                    bit.0 as nix::sys::ioctl::ioctl_param_type,
+                )
+            }
+            .map_err(nix_err)?;
+        }
+
+        Ok(self)
+    }
+
+    pub fn with_relative_axes(self, axes: &AttributeSetRef<RelativeAxisType>) -> io::Result<Self> {
+        unsafe {
+            sys::ui_set_evbit(
+                self.file.as_raw_fd(),
+                crate::EventType::RELATIVE.0 as nix::sys::ioctl::ioctl_param_type,
+            )
+        }
+        .map_err(nix_err)?;
+
+        for bit in axes.iter() {
+            unsafe {
+                sys::ui_set_relbit(
+                    self.file.as_raw_fd(),
+                    bit.0 as nix::sys::ioctl::ioctl_param_type,
+                )
+            }
+            .map_err(nix_err)?;
+        }
+
+        Ok(self)
+    }
+
+    pub fn build(self) -> io::Result<VirtualDevice> {
+        // Populate the uinput_setup struct
+
+        let mut usetup = libc::uinput_setup {
+            id: self.id.unwrap_or(DEFAULT_ID),
+            name: [0; libc::UINPUT_MAX_NAME_SIZE],
+            ff_effects_max: 0,
+        };
+
+        // SAFETY: either casting [u8] to [u8], or [u8] to [i8], which is the same size
+        let name_bytes = unsafe { &*(self.name as *const [u8] as *const [libc::c_char]) };
+        // Panic if we're doing something really stupid
+        // + 1 for the null terminator; usetup.name was zero-initialized so there will be null
+        // bytes after the part we copy into
+        assert!(name_bytes.len() + 1 < libc::UINPUT_MAX_NAME_SIZE);
+        usetup.name[..name_bytes.len()].copy_from_slice(name_bytes);
+
+        VirtualDevice::new(self.file, &usetup)
+    }
+}
+
+const DEFAULT_ID: libc::input_id = libc::input_id {
+    bustype: BusType::BUS_USB.0,
+    vendor: 0x1234,  /* sample vendor */
+    product: 0x5678, /* sample product */
+    version: 0x111,
+};
+
+pub struct VirtualDevice {
+    file: File,
+}
+
+impl VirtualDevice {
+    /// Create a new virtual device.
+    fn new(file: File, usetup: &libc::uinput_setup) -> io::Result<Self> {
+        unsafe { sys::ui_dev_setup(file.as_raw_fd(), usetup) }.map_err(nix_err)?;
+        unsafe { sys::ui_dev_create(file.as_raw_fd()) }.map_err(nix_err)?;
+
+        Ok(VirtualDevice { file })
+    }
+
+    #[inline]
+    fn write_raw(&mut self, messages: &[InputEvent]) -> io::Result<()> {
+        let bytes = unsafe { crate::cast_to_bytes(messages) };
+        self.file.write_all(bytes)
+    }
+
+    /// Post a set of messages to the virtual device.
+    ///
+    /// This inserts a SYN_REPORT for you, because apparently uinput requires that for the
+    /// kernel to realize we're done.
+    pub fn emit(&mut self, messages: &[InputEvent]) -> io::Result<()> {
+        self.write_raw(messages)?;
+
+        // Now we have to write a SYN_REPORT as well.
+        let syn = InputEvent::new(EventType::SYNCHRONIZATION, 0, 0);
+        self.write_raw(&[syn])?;
+
+        Ok(())
+    }
+}