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//! Access to currently active events.
//!
//! The udev daemon processes events asynchronously. All events which do not have
//! interdependencies run in parallel. This exports the current state of the
//! event processing queue, and the current event sequence numbers from the kernel
//! and the udev daemon.
//!
//! From `libudev-queue` documentation.
use std::io::{self, Write};
use std::os::fd::FromRawFd;
use std::{ffi, fs, sync::Arc};
use crate::UDEV_ROOT_RUN;
use crate::{Error, Result, Udev, UdevEntryList, UdevList};
/// Represents the current event queue in the udev daemon.
#[repr(C)]
#[derive(Clone, Debug, Default, PartialEq)]
pub struct UdevQueue {
udev: Arc<Udev>,
queue_list: UdevList,
fd: i32,
}
impl UdevQueue {
/// Creates a new [UdevQueue].
pub fn new(udev: Arc<Udev>) -> Self {
let udev_arc = Arc::clone(&udev);
Self {
udev,
queue_list: UdevList::new(udev_arc),
fd: -1,
}
}
/// Creates a new [UdevQueue] from the provided parameters.
pub fn create<Q: Into<UdevEntryList>>(udev: Arc<Udev>, queue_list: Q, fd: i32) -> Self {
let udev_arc = Arc::clone(&udev);
Self {
udev,
queue_list: UdevList::create(udev_arc, queue_list.into()),
fd,
}
}
/// Gets a reference to the [Udev] context.
pub const fn udev(&self) -> &Arc<Udev> {
&self.udev
}
/// Gets a reference to the queue list [UdevList].
pub const fn queue_list(&self) -> &UdevList {
&self.queue_list
}
/// Gets a mutable reference to the queue list [UdevList].
pub fn queue_list_mut(&mut self) -> &mut UdevList {
&mut self.queue_list
}
/// Sets the queue list [UdevEntryList].
pub fn set_queue_list<Q: Into<UdevEntryList>>(&mut self, queue_list: Q) {
self.queue_list.set_list(queue_list);
}
/// Builder function that sets the queue list [UdevEntryList].
pub fn with_queue_list<Q: Into<UdevEntryList>>(mut self, queue_list: Q) -> Self {
self.set_queue_list(queue_list);
self
}
/// Gets the length of the [UdevQueue].
pub fn len(&self) -> usize {
self.queue_list.len()
}
/// Gets whether the [UdevQueue] is empty.
pub fn is_empty(&self) -> bool {
self.queue_list.is_empty()
}
/// Gets the [UdevQueue] file descriptor.
pub const fn fd(&self) -> i32 {
self.fd
}
/// Sets the [UdevQueue] file descriptor.
pub fn set_fd(&mut self, val: i32) {
self.fd = val;
}
/// Builder function that sets the [UdevQueue] file descriptor.
pub fn with_fd(mut self, val: i32) -> Self {
self.set_fd(val);
self
}
/// Gets a file descriptor to watch for a queue to become empty.
pub fn get_fd(&mut self) -> Result<i32> {
if self.fd < 0 {
// SAFETY: the argument is valid, and the return value is checked before use.
let fd = unsafe { libc::inotify_init1(libc::IN_CLOEXEC) };
if fd < 0 {
let errno = io::Error::last_os_error();
let err_msg =
format!("unable to init inotify monitor, error: {fd}, errno: {errno}");
log::error!("{err_msg}");
Err(Error::UdevQueue(err_msg))
} else {
let udev_path = ffi::CString::new(format!("{UDEV_ROOT_RUN}/udev"))?;
// SAFETY: arguments are valid, and pointers reference valid memory.
let r = unsafe {
libc::inotify_add_watch(fd, udev_path.as_ptr() as *const _, libc::IN_DELETE)
};
if r < 0 {
let errno = io::Error::last_os_error();
let err_msg =
format!("unable to add inotify watch event, error: {r}, errno: {errno}");
log::error!("{err_msg}");
// SAFETY: argument is valid
unsafe { libc::close(fd) };
Err(Error::UdevQueue(err_msg))
} else {
self.fd = fd;
Ok(fd)
}
}
} else {
Ok(self.fd)
}
}
/// Clears the watched file descriptor for queue changes.
///
/// # Safety
///
/// Users must ensure that every [UdevQueue] has a unique file descriptor, if the descriptor is
/// non-negative.
///
/// Returns: `Ok(())` on success, `Err(Error)` otherwise.
pub fn flush(&mut self) -> Result<()> {
let fd = self.fd;
if fd < 0 {
let err = libc::EINVAL;
Err(Error::UdevQueue(format!(
"invalid file descriptor, fd: {fd}, error: {err}"
)))
} else {
// SAFETY: argument is valid, and only one valid mutable reference to this UdevQueue
// can be held without further `unsafe` code.
//
// Users must ensure that every UdevQueue has a unique file descriptor.
let mut file = unsafe { fs::File::from_raw_fd(fd) };
file.flush().map_err(|err| {
let errno = io::Error::last_os_error();
let err_msg =
format!("unable to flush queue file descriptor, error: {err}, errno: {errno}");
log::error!("{err_msg}");
Error::UdevQueue(err_msg)
})
}
}
/// Checks if [Udev] is active on the system.
pub fn udev_is_active(&self) -> bool {
fs::OpenOptions::new()
.read(true)
.open(format!("{UDEV_ROOT_RUN}/udev/control"))
.is_ok()
}
/// Gets whether [UdevQueue] is currently processing any events.
pub fn queue_is_empty(&self) -> bool {
fs::OpenOptions::new()
.read(true)
.open(format!("{UDEV_ROOT_RUN}/udev/queue"))
.is_ok()
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::UdevEntry;
#[test]
fn test_udev_queue() {
let udev = Arc::new(Udev::new());
let mut null_queue = UdevQueue::new(Arc::clone(&udev));
let exp_list = [UdevEntry::new().with_name("test_list_entry")];
let exp_queue = UdevQueue::create(Arc::clone(&udev), exp_list.clone(), -1);
assert!(null_queue.queue_list().is_empty());
for (entry, exp_entry) in exp_queue.queue_list().iter().zip(exp_list.iter()) {
assert_eq!(entry, exp_entry);
}
null_queue.set_queue_list(exp_list);
assert_eq!(null_queue, exp_queue);
}
}