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
157
158
159
160
161

//! Wait for events to trigger on specific file descriptors
#[cfg(any(target_os = "android", target_os = "dragonfly", target_os = "freebsd", target_os = "linux"))]
use sys::time::TimeSpec;
#[cfg(any(target_os = "android", target_os = "dragonfly", target_os = "freebsd", target_os = "linux"))]
use sys::signal::SigSet;
use std::os::unix::io::RawFd;
use std::fmt;

use libc;
use Result;
use errno::Errno;

/// This is a wrapper around `libc::pollfd`.
///
/// It's meant to be used as an argument to the [`poll`](fn.poll.html) and
/// [`ppoll`](fn.ppoll.html) functions to specify the events of interest
/// for a specific file descriptor.
///
/// After a call to `poll` or `ppoll`, the events that occured can be
/// retrieved by calling [`revents()`](#method.revents) on the `PollFd`.
#[repr(C)]
#[derive(Clone, Copy)]
pub struct PollFd {
    pollfd: libc::pollfd,
}

impl PollFd {
    /// Creates a new `PollFd` specifying the events of interest
    /// for a given file descriptor.
    pub fn new(fd: RawFd, events: PollFlags) -> PollFd {
        PollFd {
            pollfd: libc::pollfd {
                fd: fd,
                events: events.bits(),
                revents: PollFlags::empty().bits(),
            },
        }
    }

    /// Returns the events that occured in the last call to `poll` or `ppoll`.
    pub fn revents(&self) -> Option<PollFlags> {
        PollFlags::from_bits(self.pollfd.revents)
    }
}

impl fmt::Debug for PollFd {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let pfd = self.pollfd;
        let mut ds = f.debug_struct("PollFd");
        ds.field("fd", &pfd.fd);
        match PollFlags::from_bits(pfd.events) {
            None => ds.field("events", &pfd.events),
            Some(ef) => ds.field("events", &ef),
        };
        match PollFlags::from_bits(pfd.revents) {
            None => ds.field("revents", &pfd.revents),
            Some(ef) => ds.field("revents", &ef),
        };
        ds.finish()
    }
}

libc_bitflags! {
    /// These flags define the different events that can be monitored by `poll` and `ppoll`
    pub struct PollFlags: libc::c_short {
        /// There is data to read.
        POLLIN;
        /// There is some exceptional condition on the file descriptor.
        ///
        /// Possibilities include:
        ///
        /// *  There is out-of-band data on a TCP socket (see
        ///    [tcp(7)](http://man7.org/linux/man-pages/man7/tcp.7.html)).
        /// *  A pseudoterminal master in packet mode has seen a state
        ///    change on the slave (see
        ///    [ioctl_tty(2)](http://man7.org/linux/man-pages/man2/ioctl_tty.2.html)).
        /// *  A cgroup.events file has been modified (see
        ///    [cgroups(7)](http://man7.org/linux/man-pages/man7/cgroups.7.html)).
        POLLPRI;
        /// Writing is now possible, though a write larger that the
        /// available space in a socket or pipe will still block (unless
        /// `O_NONBLOCK` is set).
        POLLOUT;
        /// Equivalent to [`POLLIN`](constant.POLLIN.html)
        POLLRDNORM;
        /// Equivalent to [`POLLOUT`](constant.POLLOUT.html)
        POLLWRNORM;
        /// Priority band data can be read (generally unused on Linux).
        POLLRDBAND;
        /// Priority data may be written.
        POLLWRBAND;
        /// Error condition (only returned in
        /// [`PollFd::revents`](struct.PollFd.html#method.revents);
        /// ignored in [`PollFd::new`](struct.PollFd.html#method.new)).
        /// This bit is also set for a file descriptor referring to the
        /// write end of a pipe when the read end has been closed.
        POLLERR;
        /// Hang up (only returned in [`PollFd::revents`](struct.PollFd.html#method.revents);
        /// ignored in [`PollFd::new`](struct.PollFd.html#method.new)).
        /// Note that when reading from a channel such as a pipe or a stream
        /// socket, this event merely indicates that the peer closed its
        /// end of the channel.  Subsequent reads from the channel will
        /// return 0 (end of file) only after all outstanding data in the
        /// channel has been consumed.
        POLLHUP;
        /// Invalid request: `fd` not open (only returned in
        /// [`PollFd::revents`](struct.PollFd.html#method.revents);
        /// ignored in [`PollFd::new`](struct.PollFd.html#method.new)).
        POLLNVAL;
    }
}

/// `poll` waits for one of a set of file descriptors to become ready to perform I/O.
/// ([`poll(2)`](http://pubs.opengroup.org/onlinepubs/9699919799/functions/poll.html))
///
/// `fds` contains all [`PollFd`](struct.PollFd.html) to poll.
/// The function will return as soon as any event occur for any of these `PollFd`s.
///
/// The `timeout` argument specifies the number of milliseconds that `poll()`
/// should block waiting for a file descriptor to become ready.  The call
/// will block until either:
///
/// *  a file descriptor becomes ready;
/// *  the call is interrupted by a signal handler; or
/// *  the timeout expires.
///
/// Note that the timeout interval will be rounded up to the system clock
/// granularity, and kernel scheduling delays mean that the blocking
/// interval may overrun by a small amount.  Specifying a negative value
/// in timeout means an infinite timeout.  Specifying a timeout of zero
/// causes `poll()` to return immediately, even if no file descriptors are
/// ready.
pub fn poll(fds: &mut [PollFd], timeout: libc::c_int) -> Result<libc::c_int> {
    let res = unsafe {
        libc::poll(fds.as_mut_ptr() as *mut libc::pollfd,
                   fds.len() as libc::nfds_t,
                   timeout)
    };

    Errno::result(res)
}

/// `ppoll()` allows an application to safely wait until either a file
/// descriptor becomes ready or until a signal is caught.
/// ([`poll(2)`](http://man7.org/linux/man-pages/man2/poll.2.html))
///
/// `ppoll` behaves like `poll`, but let you specify what signals may interrupt it
/// with the `sigmask` argument.
///
#[cfg(any(target_os = "android", target_os = "dragonfly", target_os = "freebsd", target_os = "linux"))]
pub fn ppoll(fds: &mut [PollFd], timeout: TimeSpec, sigmask: SigSet) -> Result<libc::c_int> {


    let res = unsafe {
        libc::ppoll(fds.as_mut_ptr() as *mut libc::pollfd,
                    fds.len() as libc::nfds_t,
                    timeout.as_ref(),
                    sigmask.as_ref())
    };
    Errno::result(res)
}