1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156

#![cfg(target_os = "linux")]

//! # mio-udev
//!
//! This library implements abstractions around `udev` to make it usable
//! with `mio` event loop.
//!
//! # Usage
//!
//! First put the dependency on your crate's `Cargo.toml`. For example:
//!
//! ```toml
//! [dependencies]
//! mio-udev = "0.1"
//! ```
//!
//! Then import it in your crate root as:
//!
//! ```rust
//! use mio_udev;
//! ```

pub use udev::{Attribute, Attributes, Context, Device, Enumerator, Event,
               EventType, Property, Properties, Error as UdevError};

mod util;

use std::io;
use std::os::unix::io::{AsRawFd, RawFd};
use std::ffi::OsStr;

use mio::{Ready, Poll, PollOpt, Token};
use mio::event::Evented;
use mio::unix::EventedFd;

/// Monitors for device events.
///
/// A monitor communicates with the kernel over a socket. Filtering events is
/// performed efficiently in the kernel, and only events that match the filters
/// are received by the socket. Filters must be setup before listening for
/// events.
pub struct MonitorBuilder {
    builder: udev::MonitorBuilder,
}

impl MonitorBuilder {
    /// Creates a new `MonitorSocket`.
    #[inline(always)]
    pub fn new(context: &Context) -> io::Result<Self> {
        Ok(MonitorBuilder { builder: udev::MonitorBuilder::new(context)? })
    }

    /// Adds a filter that matches events for devices with the given subsystem.
    #[inline(always)]
    pub fn match_subsystem<T>(&mut self, subsystem: T) -> io::Result<()>
        where T: AsRef<OsStr>,
    {
        Ok(self.builder.match_subsystem::<T>(subsystem)?)
    }

    /// Adds a filter that matches events for devices with the given subsystem
    /// and device type.
    #[inline(always)]
    pub fn match_subsystem_devtype<T, U>(&mut self,
                                         subsystem: T,
                                         devtype: U) -> io::Result<()>
        where T: AsRef<OsStr>,
              U: AsRef<OsStr>,
    {
        Ok(self.builder.match_subsystem_devtype::<T, U>(subsystem, devtype)?)
    }

    /// Adds a filter that matches events for devices with the given tag.
    #[inline(always)]
    pub fn match_tag<T>(&mut self, tag: T) -> io::Result<()>
        where T: AsRef<OsStr>,
    {
        Ok(self.builder.match_tag::<T>(tag)?)
    }

    /// Removes all filters currently set on the monitor.
    #[inline(always)]
    pub fn clear_filters(&mut self) -> io::Result<()> {
        Ok(self.builder.clear_filters()?)
    }

    /// Listens for events matching the current filters.
    ///
    /// This method consumes the `MonitorBuilder`.
    pub fn listen(self) -> io::Result<MonitorSocket> {
        Ok(MonitorSocket::new(self.builder.listen()?)?)
    }
}

/// A wrapper around an `udev::MonitorSocket` that adds the required `mio`
/// functionality.
pub struct MonitorSocket {
    monitor: udev::MonitorSocket,
}

impl MonitorSocket {
    fn new(monitor: udev::MonitorSocket) -> io::Result<MonitorSocket> {
        use libc::{fcntl, F_GETFD, FD_CLOEXEC, F_SETFD, F_GETFL, F_SETFL, O_NONBLOCK};
        use crate::util::cvt;

        let fd = monitor.as_raw_fd();

        // Make sure the udev file descriptor is marked as CLOEXEC.
        let r = unsafe { cvt(fcntl(fd, F_GETFD))? };

        if !((r & FD_CLOEXEC) == FD_CLOEXEC) {
            unsafe { cvt(fcntl(fd, F_SETFD, r | FD_CLOEXEC))? };
        }

        // Some older versions of udev are not non-blocking by default,
        // so make sure this is set
        let r = unsafe { cvt(fcntl(fd, F_GETFL))? };

        if !((r & O_NONBLOCK) == O_NONBLOCK) {
            unsafe { cvt(fcntl(fd, F_SETFL, r | O_NONBLOCK))? };
        }

        Ok(MonitorSocket { monitor })
    }

    #[inline(always)]
    fn fd(&self) -> RawFd {
        self.monitor.as_raw_fd()
    }
}

impl Evented for MonitorSocket {
    fn register(&self, poll: &Poll, token: Token, interest: Ready, opts: PollOpt)
        -> io::Result<()>
    {
        EventedFd(&self.fd()).register(poll, token, interest, opts)
    }

    fn reregister(&self, poll: &Poll, token: Token, interest: Ready, opts: PollOpt)
        -> io::Result<()>
    {
        EventedFd(&self.fd()).reregister(poll, token, interest, opts)
    }

    fn deregister(&self, poll: &Poll) -> io::Result<()> {
        EventedFd(&self.fd()).deregister(poll)
    }
}

impl Iterator for MonitorSocket {
    type Item = Event;

    fn next(&mut self) -> Option<Self::Item> {
        self.monitor.next()
    }
}