std/os/unix/
process.rs

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
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
//! Unix-specific extensions to primitives in the [`std::process`] module.
//!
//! [`std::process`]: crate::process

#![stable(feature = "rust1", since = "1.0.0")]

use cfg_if::cfg_if;

use crate::ffi::OsStr;
use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
use crate::sealed::Sealed;
use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
use crate::{io, process, sys};

cfg_if! {
    if #[cfg(any(target_os = "vxworks", target_os = "espidf", target_os = "horizon", target_os = "vita"))] {
        type UserId = u16;
        type GroupId = u16;
    } else if #[cfg(target_os = "nto")] {
        // Both IDs are signed, see `sys/target_nto.h` of the QNX Neutrino SDP.
        // Only positive values should be used, see e.g.
        // https://www.qnx.com/developers/docs/7.1/#com.qnx.doc.neutrino.lib_ref/topic/s/setuid.html
        type UserId = i32;
        type GroupId = i32;
    } else {
        type UserId = u32;
        type GroupId = u32;
    }
}

/// Unix-specific extensions to the [`process::Command`] builder.
///
/// This trait is sealed: it cannot be implemented outside the standard library.
/// This is so that future additional methods are not breaking changes.
#[stable(feature = "rust1", since = "1.0.0")]
pub trait CommandExt: Sealed {
    /// Sets the child process's user ID. This translates to a
    /// `setuid` call in the child process. Failure in the `setuid`
    /// call will cause the spawn to fail.
    ///
    /// # Notes
    ///
    /// This will also trigger a call to `setgroups(0, NULL)` in the child
    /// process if no groups have been specified.
    /// This removes supplementary groups that might have given the child
    /// unwanted permissions.
    #[stable(feature = "rust1", since = "1.0.0")]
    fn uid(&mut self, id: UserId) -> &mut process::Command;

    /// Similar to `uid`, but sets the group ID of the child process. This has
    /// the same semantics as the `uid` field.
    #[stable(feature = "rust1", since = "1.0.0")]
    fn gid(&mut self, id: GroupId) -> &mut process::Command;

    /// Sets the supplementary group IDs for the calling process. Translates to
    /// a `setgroups` call in the child process.
    #[unstable(feature = "setgroups", issue = "90747")]
    fn groups(&mut self, groups: &[GroupId]) -> &mut process::Command;

    /// Schedules a closure to be run just before the `exec` function is
    /// invoked.
    ///
    /// The closure is allowed to return an I/O error whose OS error code will
    /// be communicated back to the parent and returned as an error from when
    /// the spawn was requested.
    ///
    /// Multiple closures can be registered and they will be called in order of
    /// their registration. If a closure returns `Err` then no further closures
    /// will be called and the spawn operation will immediately return with a
    /// failure.
    ///
    /// # Notes and Safety
    ///
    /// This closure will be run in the context of the child process after a
    /// `fork`. This primarily means that any modifications made to memory on
    /// behalf of this closure will **not** be visible to the parent process.
    /// This is often a very constrained environment where normal operations
    /// like `malloc`, accessing environment variables through [`std::env`]
    /// or acquiring a mutex are not guaranteed to work (due to
    /// other threads perhaps still running when the `fork` was run).
    ///
    /// For further details refer to the [POSIX fork() specification]
    /// and the equivalent documentation for any targeted
    /// platform, especially the requirements around *async-signal-safety*.
    ///
    /// This also means that all resources such as file descriptors and
    /// memory-mapped regions got duplicated. It is your responsibility to make
    /// sure that the closure does not violate library invariants by making
    /// invalid use of these duplicates.
    ///
    /// Panicking in the closure is safe only if all the format arguments for the
    /// panic message can be safely formatted; this is because although
    /// `Command` calls [`std::panic::always_abort`](crate::panic::always_abort)
    /// before calling the pre_exec hook, panic will still try to format the
    /// panic message.
    ///
    /// When this closure is run, aspects such as the stdio file descriptors and
    /// working directory have successfully been changed, so output to these
    /// locations might not appear where intended.
    ///
    /// [POSIX fork() specification]:
    ///     https://pubs.opengroup.org/onlinepubs/9699919799/functions/fork.html
    /// [`std::env`]: mod@crate::env
    #[stable(feature = "process_pre_exec", since = "1.34.0")]
    unsafe fn pre_exec<F>(&mut self, f: F) -> &mut process::Command
    where
        F: FnMut() -> io::Result<()> + Send + Sync + 'static;

    /// Schedules a closure to be run just before the `exec` function is
    /// invoked.
    ///
    /// `before_exec` used to be a safe method, but it needs to be unsafe since the closure may only
    /// perform operations that are *async-signal-safe*. Hence it got deprecated in favor of the
    /// unsafe [`pre_exec`]. Meanwhile, Rust gained the ability to make an existing safe method
    /// fully unsafe in a new edition, which is how `before_exec` became `unsafe`. It still also
    /// remains deprecated; `pre_exec` should be used instead.
    ///
    /// [`pre_exec`]: CommandExt::pre_exec
    #[stable(feature = "process_exec", since = "1.15.0")]
    #[deprecated(since = "1.37.0", note = "should be unsafe, use `pre_exec` instead")]
    #[rustc_deprecated_safe_2024(audit_that = "the closure is async-signal-safe")]
    unsafe fn before_exec<F>(&mut self, f: F) -> &mut process::Command
    where
        F: FnMut() -> io::Result<()> + Send + Sync + 'static,
    {
        unsafe { self.pre_exec(f) }
    }

    /// Performs all the required setup by this `Command`, followed by calling
    /// the `execvp` syscall.
    ///
    /// On success this function will not return, and otherwise it will return
    /// an error indicating why the exec (or another part of the setup of the
    /// `Command`) failed.
    ///
    /// `exec` not returning has the same implications as calling
    /// [`process::exit`] – no destructors on the current stack or any other
    /// thread’s stack will be run. Therefore, it is recommended to only call
    /// `exec` at a point where it is fine to not run any destructors. Note,
    /// that the `execvp` syscall independently guarantees that all memory is
    /// freed and all file descriptors with the `CLOEXEC` option (set by default
    /// on all file descriptors opened by the standard library) are closed.
    ///
    /// This function, unlike `spawn`, will **not** `fork` the process to create
    /// a new child. Like spawn, however, the default behavior for the stdio
    /// descriptors will be to inherited from the current process.
    ///
    /// # Notes
    ///
    /// The process may be in a "broken state" if this function returns in
    /// error. For example the working directory, environment variables, signal
    /// handling settings, various user/group information, or aspects of stdio
    /// file descriptors may have changed. If a "transactional spawn" is
    /// required to gracefully handle errors it is recommended to use the
    /// cross-platform `spawn` instead.
    #[stable(feature = "process_exec2", since = "1.9.0")]
    #[must_use]
    fn exec(&mut self) -> io::Error;

    /// Set executable argument
    ///
    /// Set the first process argument, `argv[0]`, to something other than the
    /// default executable path.
    #[stable(feature = "process_set_argv0", since = "1.45.0")]
    fn arg0<S>(&mut self, arg: S) -> &mut process::Command
    where
        S: AsRef<OsStr>;

    /// Sets the process group ID (PGID) of the child process. Equivalent to a
    /// `setpgid` call in the child process, but may be more efficient.
    ///
    /// Process groups determine which processes receive signals.
    ///
    /// # Examples
    ///
    /// Pressing Ctrl-C in a terminal will send SIGINT to all processes in
    /// the current foreground process group. By spawning the `sleep`
    /// subprocess in a new process group, it will not receive SIGINT from the
    /// terminal.
    ///
    /// The parent process could install a signal handler and manage the
    /// subprocess on its own terms.
    ///
    /// A process group ID of 0 will use the process ID as the PGID.
    ///
    /// ```no_run
    /// use std::process::Command;
    /// use std::os::unix::process::CommandExt;
    ///
    /// Command::new("sleep")
    ///     .arg("10")
    ///     .process_group(0)
    ///     .spawn()?
    ///     .wait()?;
    /// #
    /// # Ok::<_, Box<dyn std::error::Error>>(())
    /// ```
    #[stable(feature = "process_set_process_group", since = "1.64.0")]
    fn process_group(&mut self, pgroup: i32) -> &mut process::Command;
}

#[stable(feature = "rust1", since = "1.0.0")]
impl CommandExt for process::Command {
    fn uid(&mut self, id: UserId) -> &mut process::Command {
        self.as_inner_mut().uid(id);
        self
    }

    fn gid(&mut self, id: GroupId) -> &mut process::Command {
        self.as_inner_mut().gid(id);
        self
    }

    fn groups(&mut self, groups: &[GroupId]) -> &mut process::Command {
        self.as_inner_mut().groups(groups);
        self
    }

    unsafe fn pre_exec<F>(&mut self, f: F) -> &mut process::Command
    where
        F: FnMut() -> io::Result<()> + Send + Sync + 'static,
    {
        self.as_inner_mut().pre_exec(Box::new(f));
        self
    }

    fn exec(&mut self) -> io::Error {
        // NOTE: This may *not* be safe to call after `libc::fork`, because it
        // may allocate. That may be worth fixing at some point in the future.
        self.as_inner_mut().exec(sys::process::Stdio::Inherit)
    }

    fn arg0<S>(&mut self, arg: S) -> &mut process::Command
    where
        S: AsRef<OsStr>,
    {
        self.as_inner_mut().set_arg_0(arg.as_ref());
        self
    }

    fn process_group(&mut self, pgroup: i32) -> &mut process::Command {
        self.as_inner_mut().pgroup(pgroup);
        self
    }
}

/// Unix-specific extensions to [`process::ExitStatus`] and
/// [`ExitStatusError`](process::ExitStatusError).
///
/// On Unix, `ExitStatus` **does not necessarily represent an exit status**, as
/// passed to the `_exit` system call or returned by
/// [`ExitStatus::code()`](crate::process::ExitStatus::code).  It represents **any wait status**
/// as returned by one of the `wait` family of system
/// calls.
///
/// A Unix wait status (a Rust `ExitStatus`) can represent a Unix exit status, but can also
/// represent other kinds of process event.
///
/// This trait is sealed: it cannot be implemented outside the standard library.
/// This is so that future additional methods are not breaking changes.
#[stable(feature = "rust1", since = "1.0.0")]
pub trait ExitStatusExt: Sealed {
    /// Creates a new `ExitStatus` or `ExitStatusError` from the raw underlying integer status
    /// value from `wait`
    ///
    /// The value should be a **wait status, not an exit status**.
    ///
    /// # Panics
    ///
    /// Panics on an attempt to make an `ExitStatusError` from a wait status of `0`.
    ///
    /// Making an `ExitStatus` always succeeds and never panics.
    #[stable(feature = "exit_status_from", since = "1.12.0")]
    fn from_raw(raw: i32) -> Self;

    /// If the process was terminated by a signal, returns that signal.
    ///
    /// In other words, if `WIFSIGNALED`, this returns `WTERMSIG`.
    #[stable(feature = "rust1", since = "1.0.0")]
    fn signal(&self) -> Option<i32>;

    /// If the process was terminated by a signal, says whether it dumped core.
    #[stable(feature = "unix_process_wait_more", since = "1.58.0")]
    fn core_dumped(&self) -> bool;

    /// If the process was stopped by a signal, returns that signal.
    ///
    /// In other words, if `WIFSTOPPED`, this returns `WSTOPSIG`.  This is only possible if the status came from
    /// a `wait` system call which was passed `WUNTRACED`, and was then converted into an `ExitStatus`.
    #[stable(feature = "unix_process_wait_more", since = "1.58.0")]
    fn stopped_signal(&self) -> Option<i32>;

    /// Whether the process was continued from a stopped status.
    ///
    /// Ie, `WIFCONTINUED`.  This is only possible if the status came from a `wait` system call
    /// which was passed `WCONTINUED`, and was then converted into an `ExitStatus`.
    #[stable(feature = "unix_process_wait_more", since = "1.58.0")]
    fn continued(&self) -> bool;

    /// Returns the underlying raw `wait` status.
    ///
    /// The returned integer is a **wait status, not an exit status**.
    #[stable(feature = "unix_process_wait_more", since = "1.58.0")]
    fn into_raw(self) -> i32;
}

#[stable(feature = "rust1", since = "1.0.0")]
impl ExitStatusExt for process::ExitStatus {
    fn from_raw(raw: i32) -> Self {
        process::ExitStatus::from_inner(From::from(raw))
    }

    fn signal(&self) -> Option<i32> {
        self.as_inner().signal()
    }

    fn core_dumped(&self) -> bool {
        self.as_inner().core_dumped()
    }

    fn stopped_signal(&self) -> Option<i32> {
        self.as_inner().stopped_signal()
    }

    fn continued(&self) -> bool {
        self.as_inner().continued()
    }

    fn into_raw(self) -> i32 {
        self.as_inner().into_raw().into()
    }
}

#[unstable(feature = "exit_status_error", issue = "84908")]
impl ExitStatusExt for process::ExitStatusError {
    fn from_raw(raw: i32) -> Self {
        process::ExitStatus::from_raw(raw)
            .exit_ok()
            .expect_err("<ExitStatusError as ExitStatusExt>::from_raw(0) but zero is not an error")
    }

    fn signal(&self) -> Option<i32> {
        self.into_status().signal()
    }

    fn core_dumped(&self) -> bool {
        self.into_status().core_dumped()
    }

    fn stopped_signal(&self) -> Option<i32> {
        self.into_status().stopped_signal()
    }

    fn continued(&self) -> bool {
        self.into_status().continued()
    }

    fn into_raw(self) -> i32 {
        self.into_status().into_raw()
    }
}

#[stable(feature = "process_extensions", since = "1.2.0")]
impl FromRawFd for process::Stdio {
    #[inline]
    unsafe fn from_raw_fd(fd: RawFd) -> process::Stdio {
        let fd = sys::fd::FileDesc::from_raw_fd(fd);
        let io = sys::process::Stdio::Fd(fd);
        process::Stdio::from_inner(io)
    }
}

#[stable(feature = "io_safety", since = "1.63.0")]
impl From<OwnedFd> for process::Stdio {
    /// Takes ownership of a file descriptor and returns a [`Stdio`](process::Stdio)
    /// that can attach a stream to it.
    #[inline]
    fn from(fd: OwnedFd) -> process::Stdio {
        let fd = sys::fd::FileDesc::from_inner(fd);
        let io = sys::process::Stdio::Fd(fd);
        process::Stdio::from_inner(io)
    }
}

#[stable(feature = "process_extensions", since = "1.2.0")]
impl AsRawFd for process::ChildStdin {
    #[inline]
    fn as_raw_fd(&self) -> RawFd {
        self.as_inner().as_raw_fd()
    }
}

#[stable(feature = "process_extensions", since = "1.2.0")]
impl AsRawFd for process::ChildStdout {
    #[inline]
    fn as_raw_fd(&self) -> RawFd {
        self.as_inner().as_raw_fd()
    }
}

#[stable(feature = "process_extensions", since = "1.2.0")]
impl AsRawFd for process::ChildStderr {
    #[inline]
    fn as_raw_fd(&self) -> RawFd {
        self.as_inner().as_raw_fd()
    }
}

#[stable(feature = "into_raw_os", since = "1.4.0")]
impl IntoRawFd for process::ChildStdin {
    #[inline]
    fn into_raw_fd(self) -> RawFd {
        self.into_inner().into_inner().into_raw_fd()
    }
}

#[stable(feature = "into_raw_os", since = "1.4.0")]
impl IntoRawFd for process::ChildStdout {
    #[inline]
    fn into_raw_fd(self) -> RawFd {
        self.into_inner().into_inner().into_raw_fd()
    }
}

#[stable(feature = "into_raw_os", since = "1.4.0")]
impl IntoRawFd for process::ChildStderr {
    #[inline]
    fn into_raw_fd(self) -> RawFd {
        self.into_inner().into_inner().into_raw_fd()
    }
}

#[stable(feature = "io_safety", since = "1.63.0")]
impl AsFd for crate::process::ChildStdin {
    #[inline]
    fn as_fd(&self) -> BorrowedFd<'_> {
        self.as_inner().as_fd()
    }
}

#[stable(feature = "io_safety", since = "1.63.0")]
impl From<crate::process::ChildStdin> for OwnedFd {
    /// Takes ownership of a [`ChildStdin`](crate::process::ChildStdin)'s file descriptor.
    #[inline]
    fn from(child_stdin: crate::process::ChildStdin) -> OwnedFd {
        child_stdin.into_inner().into_inner().into_inner()
    }
}

/// Creates a `ChildStdin` from the provided `OwnedFd`.
///
/// The provided file descriptor must point to a pipe
/// with the `CLOEXEC` flag set.
#[stable(feature = "child_stream_from_fd", since = "1.74.0")]
impl From<OwnedFd> for process::ChildStdin {
    #[inline]
    fn from(fd: OwnedFd) -> process::ChildStdin {
        let fd = sys::fd::FileDesc::from_inner(fd);
        let pipe = sys::pipe::AnonPipe::from_inner(fd);
        process::ChildStdin::from_inner(pipe)
    }
}

#[stable(feature = "io_safety", since = "1.63.0")]
impl AsFd for crate::process::ChildStdout {
    #[inline]
    fn as_fd(&self) -> BorrowedFd<'_> {
        self.as_inner().as_fd()
    }
}

#[stable(feature = "io_safety", since = "1.63.0")]
impl From<crate::process::ChildStdout> for OwnedFd {
    /// Takes ownership of a [`ChildStdout`](crate::process::ChildStdout)'s file descriptor.
    #[inline]
    fn from(child_stdout: crate::process::ChildStdout) -> OwnedFd {
        child_stdout.into_inner().into_inner().into_inner()
    }
}

/// Creates a `ChildStdout` from the provided `OwnedFd`.
///
/// The provided file descriptor must point to a pipe
/// with the `CLOEXEC` flag set.
#[stable(feature = "child_stream_from_fd", since = "1.74.0")]
impl From<OwnedFd> for process::ChildStdout {
    #[inline]
    fn from(fd: OwnedFd) -> process::ChildStdout {
        let fd = sys::fd::FileDesc::from_inner(fd);
        let pipe = sys::pipe::AnonPipe::from_inner(fd);
        process::ChildStdout::from_inner(pipe)
    }
}

#[stable(feature = "io_safety", since = "1.63.0")]
impl AsFd for crate::process::ChildStderr {
    #[inline]
    fn as_fd(&self) -> BorrowedFd<'_> {
        self.as_inner().as_fd()
    }
}

#[stable(feature = "io_safety", since = "1.63.0")]
impl From<crate::process::ChildStderr> for OwnedFd {
    /// Takes ownership of a [`ChildStderr`](crate::process::ChildStderr)'s file descriptor.
    #[inline]
    fn from(child_stderr: crate::process::ChildStderr) -> OwnedFd {
        child_stderr.into_inner().into_inner().into_inner()
    }
}

/// Creates a `ChildStderr` from the provided `OwnedFd`.
///
/// The provided file descriptor must point to a pipe
/// with the `CLOEXEC` flag set.
#[stable(feature = "child_stream_from_fd", since = "1.74.0")]
impl From<OwnedFd> for process::ChildStderr {
    #[inline]
    fn from(fd: OwnedFd) -> process::ChildStderr {
        let fd = sys::fd::FileDesc::from_inner(fd);
        let pipe = sys::pipe::AnonPipe::from_inner(fd);
        process::ChildStderr::from_inner(pipe)
    }
}

/// Returns the OS-assigned process identifier associated with this process's parent.
#[must_use]
#[stable(feature = "unix_ppid", since = "1.27.0")]
pub fn parent_id() -> u32 {
    crate::sys::os::getppid()
}