summaryrefslogtreecommitdiff
path: root/src/sys/select.rs
blob: 1b518e29f67a68d4fdef71345a2c3048f99c3493 (plain)
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
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
use std::mem;
use std::os::unix::io::RawFd;
use std::ptr::{null, null_mut};
use libc::{self, c_int};
use Result;
use errno::Errno;
use sys::signal::SigSet;
use sys::time::{TimeSpec, TimeVal};

pub use libc::FD_SETSIZE;

// FIXME: Change to repr(transparent) once it's stable
#[repr(C)]
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub struct FdSet(libc::fd_set);

impl FdSet {
    pub fn new() -> FdSet {
        let mut fdset = unsafe { mem::uninitialized() };
        unsafe { libc::FD_ZERO(&mut fdset) };
        FdSet(fdset)
    }

    pub fn insert(&mut self, fd: RawFd) {
        unsafe { libc::FD_SET(fd, &mut self.0) };
    }

    pub fn remove(&mut self, fd: RawFd) {
        unsafe { libc::FD_CLR(fd, &mut self.0) };
    }

    pub fn contains(&mut self, fd: RawFd) -> bool {
        unsafe { libc::FD_ISSET(fd, &mut self.0) }
    }

    pub fn clear(&mut self) {
        unsafe { libc::FD_ZERO(&mut self.0) };
    }

    /// Finds the highest file descriptor in the set.
    ///
    /// Returns `None` if the set is empty.
    ///
    /// This can be used to calculate the `nfds` parameter of the [`select`] function.
    ///
    /// # Example
    ///
    /// ```
    /// # extern crate nix;
    /// # use nix::sys::select::FdSet;
    /// # fn main() {
    /// let mut set = FdSet::new();
    /// set.insert(4);
    /// set.insert(9);
    /// assert_eq!(set.highest(), Some(9));
    /// # }
    /// ```
    ///
    /// [`select`]: fn.select.html
    pub fn highest(&mut self) -> Option<RawFd> {
        for i in (0..FD_SETSIZE).rev() {
            let i = i as RawFd;
            if unsafe { libc::FD_ISSET(i, self as *mut _ as *mut libc::fd_set) } {
                return Some(i)
            }
        }

        None
    }
}

/// Monitors file descriptors for readiness
///
/// Returns the total number of ready file descriptors in all sets. The sets are changed so that all
/// file descriptors that are ready for the given operation are set.
///
/// When this function returns, `timeout` has an implementation-defined value.
///
/// # Parameters
///
/// * `nfds`: The highest file descriptor set in any of the passed `FdSet`s, plus 1. If `None`, this
///   is calculated automatically by calling [`FdSet::highest`] on all descriptor sets and adding 1
///   to the maximum of that.
/// * `readfds`: File descriptors to check for being ready to read.
/// * `writefds`: File descriptors to check for being ready to write.
/// * `errorfds`: File descriptors to check for pending error conditions.
/// * `timeout`: Maximum time to wait for descriptors to become ready (`None` to block
///   indefinitely).
///
/// # References
///
/// [select(2)](http://pubs.opengroup.org/onlinepubs/9699919799/functions/select.html)
///
/// [`FdSet::highest`]: struct.FdSet.html#method.highest
pub fn select<'a, N, R, W, E, T>(nfds: N,
                                 readfds: R,
                                 writefds: W,
                                 errorfds: E,
                                 timeout: T) -> Result<c_int>
where
    N: Into<Option<c_int>>,
    R: Into<Option<&'a mut FdSet>>,
    W: Into<Option<&'a mut FdSet>>,
    E: Into<Option<&'a mut FdSet>>,
    T: Into<Option<&'a mut TimeVal>>,
{
    let mut readfds = readfds.into();
    let mut writefds = writefds.into();
    let mut errorfds = errorfds.into();
    let timeout = timeout.into();

    let nfds = nfds.into().unwrap_or_else(|| {
        readfds.iter_mut()
            .chain(writefds.iter_mut())
            .chain(errorfds.iter_mut())
            .map(|set| set.highest().unwrap_or(-1))
            .max()
            .unwrap_or(-1) + 1
    });

    let readfds = readfds.map(|set| set as *mut _ as *mut libc::fd_set).unwrap_or(null_mut());
    let writefds = writefds.map(|set| set as *mut _ as *mut libc::fd_set).unwrap_or(null_mut());
    let errorfds = errorfds.map(|set| set as *mut _ as *mut libc::fd_set).unwrap_or(null_mut());
    let timeout = timeout.map(|tv| tv as *mut _ as *mut libc::timeval)
                         .unwrap_or(null_mut());

    let res = unsafe {
        libc::select(nfds, readfds, writefds, errorfds, timeout)
    };

    Errno::result(res)
}

/// Monitors file descriptors for readiness with an altered signal mask.
///
/// Returns the total number of ready file descriptors in all sets. The sets are changed so that all
/// file descriptors that are ready for the given operation are set.
///
/// When this function returns, the original signal mask is restored.
///
/// Unlike [`select`](#fn.select), `pselect` does not mutate the `timeout` value.
///
/// # Parameters
///
/// * `nfds`: The highest file descriptor set in any of the passed `FdSet`s, plus 1. If `None`, this
///   is calculated automatically by calling [`FdSet::highest`] on all descriptor sets and adding 1
///   to the maximum of that.
/// * `readfds`: File descriptors to check for read readiness
/// * `writefds`: File descriptors to check for write readiness
/// * `errorfds`: File descriptors to check for pending error conditions.
/// * `timeout`: Maximum time to wait for descriptors to become ready (`None` to block
///   indefinitely).
/// * `sigmask`: Signal mask to activate while waiting for file descriptors to turn
///    ready (`None` to set no alternative signal mask).
///
/// # References
///
/// [pselect(2)](http://pubs.opengroup.org/onlinepubs/9699919799/functions/pselect.html)
///
/// [The new pselect() system call](https://lwn.net/Articles/176911/)
///
/// [`FdSet::highest`]: struct.FdSet.html#method.highest
pub fn pselect<'a, N, R, W, E, T, S>(nfds: N,
                                     readfds: R,
                                     writefds: W,
                                     errorfds: E,
                                     timeout: T,
                                     sigmask: S) -> Result<c_int>
where
    N: Into<Option<c_int>>,
    R: Into<Option<&'a mut FdSet>>,
    W: Into<Option<&'a mut FdSet>>,
    E: Into<Option<&'a mut FdSet>>,
    T: Into<Option<&'a TimeSpec>>,
    S: Into<Option<&'a SigSet>>,
{
    let mut readfds = readfds.into();
    let mut writefds = writefds.into();
    let mut errorfds = errorfds.into();
    let sigmask = sigmask.into();
    let timeout = timeout.into();

    let nfds = nfds.into().unwrap_or_else(|| {
        readfds.iter_mut()
            .chain(writefds.iter_mut())
            .chain(errorfds.iter_mut())
            .map(|set| set.highest().unwrap_or(-1))
            .max()
            .unwrap_or(-1) + 1
    });

    let readfds = readfds.map(|set| set as *mut _ as *mut libc::fd_set).unwrap_or(null_mut());
    let writefds = writefds.map(|set| set as *mut _ as *mut libc::fd_set).unwrap_or(null_mut());
    let errorfds = errorfds.map(|set| set as *mut _ as *mut libc::fd_set).unwrap_or(null_mut());
    let timeout = timeout.map(|ts| ts.as_ref() as *const libc::timespec).unwrap_or(null());
    let sigmask = sigmask.map(|sm| sm.as_ref() as *const libc::sigset_t).unwrap_or(null());

    let res = unsafe {
        libc::pselect(nfds, readfds, writefds, errorfds, timeout, sigmask)
    };

    Errno::result(res)
}


#[cfg(test)]
mod tests {
    use super::*;
    use std::os::unix::io::RawFd;
    use sys::time::{TimeVal, TimeValLike};
    use unistd::{write, pipe};

    #[test]
    fn fdset_insert() {
        let mut fd_set = FdSet::new();

        for i in 0..FD_SETSIZE {
            assert!(!fd_set.contains(i as RawFd));
        }

        fd_set.insert(7);

        assert!(fd_set.contains(7));
    }

    #[test]
    fn fdset_remove() {
        let mut fd_set = FdSet::new();

        for i in 0..FD_SETSIZE {
            assert!(!fd_set.contains(i as RawFd));
        }

        fd_set.insert(7);
        fd_set.remove(7);

        for i in 0..FD_SETSIZE {
            assert!(!fd_set.contains(i as RawFd));
        }
    }

    #[test]
    fn fdset_clear() {
        let mut fd_set = FdSet::new();
        fd_set.insert(1);
        fd_set.insert((FD_SETSIZE / 2) as RawFd);
        fd_set.insert((FD_SETSIZE - 1) as RawFd);

        fd_set.clear();

        for i in 0..FD_SETSIZE {
            assert!(!fd_set.contains(i as RawFd));
        }
    }

    #[test]
    fn fdset_highest() {
        let mut set = FdSet::new();
        assert_eq!(set.highest(), None);
        set.insert(0);
        assert_eq!(set.highest(), Some(0));
        set.insert(90);
        assert_eq!(set.highest(), Some(90));
        set.remove(0);
        assert_eq!(set.highest(), Some(90));
        set.remove(90);
        assert_eq!(set.highest(), None);

        set.insert(4);
        set.insert(5);
        set.insert(7);
        assert_eq!(set.highest(), Some(7));
    }

    #[test]
    fn test_select() {
        let (r1, w1) = pipe().unwrap();
        write(w1, b"hi!").unwrap();
        let (r2, _w2) = pipe().unwrap();

        let mut fd_set = FdSet::new();
        fd_set.insert(r1);
        fd_set.insert(r2);

        let mut timeout = TimeVal::seconds(10);
        assert_eq!(1, select(None,
                             &mut fd_set,
                             None,
                             None,
                             &mut timeout).unwrap());
        assert!(fd_set.contains(r1));
        assert!(!fd_set.contains(r2));
    }

    #[test]
    fn test_select_nfds() {
        let (r1, w1) = pipe().unwrap();
        write(w1, b"hi!").unwrap();
        let (r2, _w2) = pipe().unwrap();

        let mut fd_set = FdSet::new();
        fd_set.insert(r1);
        fd_set.insert(r2);

        let mut timeout = TimeVal::seconds(10);
        assert_eq!(1, select(Some(fd_set.highest().unwrap() + 1),
                             &mut fd_set,
                             None,
                             None,
                             &mut timeout).unwrap());
        assert!(fd_set.contains(r1));
        assert!(!fd_set.contains(r2));
    }

    #[test]
    fn test_select_nfds2() {
        let (r1, w1) = pipe().unwrap();
        write(w1, b"hi!").unwrap();
        let (r2, _w2) = pipe().unwrap();

        let mut fd_set = FdSet::new();
        fd_set.insert(r1);
        fd_set.insert(r2);

        let mut timeout = TimeVal::seconds(10);
        assert_eq!(1, select(::std::cmp::max(r1, r2) + 1,
                             &mut fd_set,
                             None,
                             None,
                             &mut timeout).unwrap());
        assert!(fd_set.contains(r1));
        assert!(!fd_set.contains(r2));
    }
}