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
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
//! Wait for a process to change status
use crate::errno::Errno;
use crate::sys::signal::Signal;
use crate::unistd::Pid;
use crate::Result;
use cfg_if::cfg_if;
use libc::{self, c_int};
use std::convert::TryFrom;
#[cfg(any(
    target_os = "android",
    all(target_os = "linux", not(target_env = "uclibc")),
))]
use std::os::unix::io::{AsRawFd, BorrowedFd};

libc_bitflags!(
    /// Controls the behavior of [`waitpid`].
    pub struct WaitPidFlag: c_int {
        /// Do not block when there are no processes wishing to report status.
        WNOHANG;
        /// Report the status of selected processes which are stopped due to a
        /// [`SIGTTIN`](crate::sys::signal::Signal::SIGTTIN),
        /// [`SIGTTOU`](crate::sys::signal::Signal::SIGTTOU),
        /// [`SIGTSTP`](crate::sys::signal::Signal::SIGTSTP), or
        /// [`SIGSTOP`](crate::sys::signal::Signal::SIGSTOP) signal.
        WUNTRACED;
        /// Report the status of selected processes which have terminated.
        #[cfg(any(target_os = "android",
                  target_os = "freebsd",
                  target_os = "haiku",
                  target_os = "ios",
                  target_os = "linux",
                  target_os = "redox",
                  target_os = "macos",
                  target_os = "netbsd"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        WEXITED;
        /// Report the status of selected processes that have continued from a
        /// job control stop by receiving a
        /// [`SIGCONT`](crate::sys::signal::Signal::SIGCONT) signal.
        WCONTINUED;
        /// An alias for WUNTRACED.
        #[cfg(any(target_os = "android",
                  target_os = "freebsd",
                  target_os = "haiku",
                  target_os = "ios",
                  target_os = "linux",
                  target_os = "redox",
                  target_os = "macos",
                  target_os = "netbsd"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        WSTOPPED;
        /// Don't reap, just poll status.
        #[cfg(any(target_os = "android",
                  target_os = "freebsd",
                  target_os = "haiku",
                  target_os = "ios",
                  target_os = "linux",
                  target_os = "redox",
                  target_os = "macos",
                  target_os = "netbsd"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        WNOWAIT;
        /// Don't wait on children of other threads in this group
        #[cfg(any(target_os = "android", target_os = "linux", target_os = "redox"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        __WNOTHREAD;
        /// Wait on all children, regardless of type
        #[cfg(any(target_os = "android", target_os = "linux", target_os = "redox"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        __WALL;
        /// Wait for "clone" children only.
        #[cfg(any(target_os = "android", target_os = "linux", target_os = "redox"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        __WCLONE;
    }
);

/// Possible return values from `wait()` or `waitpid()`.
///
/// Each status (other than `StillAlive`) describes a state transition
/// in a child process `Pid`, such as the process exiting or stopping,
/// plus additional data about the transition if any.
///
/// Note that there are two Linux-specific enum variants, `PtraceEvent`
/// and `PtraceSyscall`. Portable code should avoid exhaustively
/// matching on `WaitStatus`.
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub enum WaitStatus {
    /// The process exited normally (as with `exit()` or returning from
    /// `main`) with the given exit code. This case matches the C macro
    /// `WIFEXITED(status)`; the second field is `WEXITSTATUS(status)`.
    Exited(Pid, i32),
    /// The process was killed by the given signal. The third field
    /// indicates whether the signal generated a core dump. This case
    /// matches the C macro `WIFSIGNALED(status)`; the last two fields
    /// correspond to `WTERMSIG(status)` and `WCOREDUMP(status)`.
    Signaled(Pid, Signal, bool),
    /// The process is alive, but was stopped by the given signal. This
    /// is only reported if `WaitPidFlag::WUNTRACED` was passed. This
    /// case matches the C macro `WIFSTOPPED(status)`; the second field
    /// is `WSTOPSIG(status)`.
    Stopped(Pid, Signal),
    /// The traced process was stopped by a `PTRACE_EVENT_*` event. See
    /// [`nix::sys::ptrace`] and [`ptrace`(2)] for more information. All
    /// currently-defined events use `SIGTRAP` as the signal; the third
    /// field is the `PTRACE_EVENT_*` value of the event.
    ///
    /// [`nix::sys::ptrace`]: ../ptrace/index.html
    /// [`ptrace`(2)]: https://man7.org/linux/man-pages/man2/ptrace.2.html
    #[cfg(any(target_os = "linux", target_os = "android"))]
    #[cfg_attr(docsrs, doc(cfg(all())))]
    PtraceEvent(Pid, Signal, c_int),
    /// The traced process was stopped by execution of a system call,
    /// and `PTRACE_O_TRACESYSGOOD` is in effect. See [`ptrace`(2)] for
    /// more information.
    ///
    /// [`ptrace`(2)]: https://man7.org/linux/man-pages/man2/ptrace.2.html
    #[cfg(any(target_os = "linux", target_os = "android"))]
    #[cfg_attr(docsrs, doc(cfg(all())))]
    PtraceSyscall(Pid),
    /// The process was previously stopped but has resumed execution
    /// after receiving a `SIGCONT` signal. This is only reported if
    /// `WaitPidFlag::WCONTINUED` was passed. This case matches the C
    /// macro `WIFCONTINUED(status)`.
    Continued(Pid),
    /// There are currently no state changes to report in any awaited
    /// child process. This is only returned if `WaitPidFlag::WNOHANG`
    /// was used (otherwise `wait()` or `waitpid()` would block until
    /// there was something to report).
    StillAlive,
}

impl WaitStatus {
    /// Extracts the PID from the WaitStatus unless it equals StillAlive.
    pub fn pid(&self) -> Option<Pid> {
        use self::WaitStatus::*;
        match *self {
            Exited(p, _) | Signaled(p, _, _) | Stopped(p, _) | Continued(p) => {
                Some(p)
            }
            StillAlive => None,
            #[cfg(any(target_os = "android", target_os = "linux"))]
            PtraceEvent(p, _, _) | PtraceSyscall(p) => Some(p),
        }
    }
}

fn exited(status: i32) -> bool {
    libc::WIFEXITED(status)
}

fn exit_status(status: i32) -> i32 {
    libc::WEXITSTATUS(status)
}

fn signaled(status: i32) -> bool {
    libc::WIFSIGNALED(status)
}

fn term_signal(status: i32) -> Result<Signal> {
    Signal::try_from(libc::WTERMSIG(status))
}

fn dumped_core(status: i32) -> bool {
    libc::WCOREDUMP(status)
}

fn stopped(status: i32) -> bool {
    libc::WIFSTOPPED(status)
}

fn stop_signal(status: i32) -> Result<Signal> {
    Signal::try_from(libc::WSTOPSIG(status))
}

#[cfg(any(target_os = "android", target_os = "linux"))]
fn syscall_stop(status: i32) -> bool {
    // From ptrace(2), setting PTRACE_O_TRACESYSGOOD has the effect
    // of delivering SIGTRAP | 0x80 as the signal number for syscall
    // stops. This allows easily distinguishing syscall stops from
    // genuine SIGTRAP signals.
    libc::WSTOPSIG(status) == libc::SIGTRAP | 0x80
}

#[cfg(any(target_os = "android", target_os = "linux"))]
fn stop_additional(status: i32) -> c_int {
    (status >> 16) as c_int
}

fn continued(status: i32) -> bool {
    libc::WIFCONTINUED(status)
}

impl WaitStatus {
    /// Convert a raw `wstatus` as returned by `waitpid`/`wait` into a `WaitStatus`
    ///
    /// # Errors
    ///
    /// Returns an `Error` corresponding to `EINVAL` for invalid status values.
    ///
    /// # Examples
    ///
    /// Convert a `wstatus` obtained from `libc::waitpid` into a `WaitStatus`:
    ///
    /// ```
    /// use nix::sys::wait::WaitStatus;
    /// use nix::sys::signal::Signal;
    /// let pid = nix::unistd::Pid::from_raw(1);
    /// let status = WaitStatus::from_raw(pid, 0x0002);
    /// assert_eq!(status, Ok(WaitStatus::Signaled(pid, Signal::SIGINT, false)));
    /// ```
    pub fn from_raw(pid: Pid, status: i32) -> Result<WaitStatus> {
        Ok(if exited(status) {
            WaitStatus::Exited(pid, exit_status(status))
        } else if signaled(status) {
            WaitStatus::Signaled(pid, term_signal(status)?, dumped_core(status))
        } else if stopped(status) {
            cfg_if! {
                if #[cfg(any(target_os = "android", target_os = "linux"))] {
                    fn decode_stopped(pid: Pid, status: i32) -> Result<WaitStatus> {
                        let status_additional = stop_additional(status);
                        Ok(if syscall_stop(status) {
                            WaitStatus::PtraceSyscall(pid)
                        } else if status_additional == 0 {
                            WaitStatus::Stopped(pid, stop_signal(status)?)
                        } else {
                            WaitStatus::PtraceEvent(pid, stop_signal(status)?,
                                                    stop_additional(status))
                        })
                    }
                } else {
                    fn decode_stopped(pid: Pid, status: i32) -> Result<WaitStatus> {
                        Ok(WaitStatus::Stopped(pid, stop_signal(status)?))
                    }
                }
            }
            return decode_stopped(pid, status);
        } else {
            assert!(continued(status));
            WaitStatus::Continued(pid)
        })
    }

    /// Convert a `siginfo_t` as returned by `waitid` to a `WaitStatus`
    ///
    /// # Errors
    ///
    /// Returns an `Error` corresponding to `EINVAL` for invalid values.
    ///
    /// # Safety
    ///
    /// siginfo_t is actually a union, not all fields may be initialized.
    /// The functions si_pid() and si_status() must be valid to call on
    /// the passed siginfo_t.
    #[cfg(any(
        target_os = "android",
        target_os = "freebsd",
        target_os = "haiku",
        all(target_os = "linux", not(target_env = "uclibc")),
    ))]
    unsafe fn from_siginfo(siginfo: &libc::siginfo_t) -> Result<WaitStatus> {
        let si_pid = siginfo.si_pid();
        if si_pid == 0 {
            return Ok(WaitStatus::StillAlive);
        }

        assert_eq!(siginfo.si_signo, libc::SIGCHLD);

        let pid = Pid::from_raw(si_pid);
        let si_status = siginfo.si_status();

        let status = match siginfo.si_code {
            libc::CLD_EXITED => WaitStatus::Exited(pid, si_status),
            libc::CLD_KILLED | libc::CLD_DUMPED => WaitStatus::Signaled(
                pid,
                Signal::try_from(si_status)?,
                siginfo.si_code == libc::CLD_DUMPED,
            ),
            libc::CLD_STOPPED => {
                WaitStatus::Stopped(pid, Signal::try_from(si_status)?)
            }
            libc::CLD_CONTINUED => WaitStatus::Continued(pid),
            #[cfg(any(target_os = "android", target_os = "linux"))]
            libc::CLD_TRAPPED => {
                if si_status == libc::SIGTRAP | 0x80 {
                    WaitStatus::PtraceSyscall(pid)
                } else {
                    WaitStatus::PtraceEvent(
                        pid,
                        Signal::try_from(si_status & 0xff)?,
                        (si_status >> 8) as c_int,
                    )
                }
            }
            _ => return Err(Errno::EINVAL),
        };

        Ok(status)
    }
}

/// Wait for a process to change status
///
/// See also [waitpid(2)](https://pubs.opengroup.org/onlinepubs/9699919799/functions/waitpid.html)
pub fn waitpid<P: Into<Option<Pid>>>(
    pid: P,
    options: Option<WaitPidFlag>,
) -> Result<WaitStatus> {
    use self::WaitStatus::*;

    let mut status: i32 = 0;

    let option_bits = match options {
        Some(bits) => bits.bits(),
        None => 0,
    };

    let res = unsafe {
        libc::waitpid(
            pid.into().unwrap_or_else(|| Pid::from_raw(-1)).into(),
            &mut status as *mut c_int,
            option_bits,
        )
    };

    match Errno::result(res)? {
        0 => Ok(StillAlive),
        res => WaitStatus::from_raw(Pid::from_raw(res), status),
    }
}

/// Wait for any child process to change status or a signal is received.
///
/// See also [wait(2)](https://pubs.opengroup.org/onlinepubs/9699919799/functions/wait.html)
pub fn wait() -> Result<WaitStatus> {
    waitpid(None, None)
}

/// The ID argument for `waitid`
#[cfg(any(
    target_os = "android",
    target_os = "freebsd",
    target_os = "haiku",
    all(target_os = "linux", not(target_env = "uclibc")),
))]
#[derive(Debug)]
pub enum Id<'fd> {
    /// Wait for any child
    All,
    /// Wait for the child whose process ID matches the given PID
    Pid(Pid),
    /// Wait for the child whose process group ID matches the given PID
    ///
    /// If the PID is zero, the caller's process group is used since Linux 5.4.
    PGid(Pid),
    /// Wait for the child referred to by the given PID file descriptor
    #[cfg(any(target_os = "android", target_os = "linux"))]
    PIDFd(BorrowedFd<'fd>),
    /// A helper variant to resolve the unused parameter (`'fd`) problem on platforms
    /// other than Linux and Android.
    #[doc(hidden)]
    _Unreachable(std::marker::PhantomData<&'fd std::convert::Infallible>),
}

/// Wait for a process to change status
///
/// See also [waitid(2)](https://pubs.opengroup.org/onlinepubs/9699919799/functions/waitid.html)
#[cfg(any(
    target_os = "android",
    target_os = "freebsd",
    target_os = "haiku",
    all(target_os = "linux", not(target_env = "uclibc")),
))]
pub fn waitid(id: Id, flags: WaitPidFlag) -> Result<WaitStatus> {
    let (idtype, idval) = match id {
        Id::All => (libc::P_ALL, 0),
        Id::Pid(pid) => (libc::P_PID, pid.as_raw() as libc::id_t),
        Id::PGid(pid) => (libc::P_PGID, pid.as_raw() as libc::id_t),
        #[cfg(any(target_os = "android", target_os = "linux"))]
        Id::PIDFd(fd) => (libc::P_PIDFD, fd.as_raw_fd() as libc::id_t),
        Id::_Unreachable(_) => unreachable!("This variant could never be constructed"),
    };

    let siginfo = unsafe {
        // Memory is zeroed rather than uninitialized, as not all platforms
        // initialize the memory in the StillAlive case
        let mut siginfo: libc::siginfo_t = std::mem::zeroed();
        Errno::result(libc::waitid(idtype, idval, &mut siginfo, flags.bits()))?;
        siginfo
    };

    unsafe { WaitStatus::from_siginfo(&siginfo) }
}