std/sys/pal/unix/process/
process_common.rs

1#[cfg(all(test, not(target_os = "emscripten")))]
2mod tests;
3
4use libc::{EXIT_FAILURE, EXIT_SUCCESS, c_char, c_int, gid_t, pid_t, uid_t};
5
6use crate::collections::BTreeMap;
7use crate::ffi::{CStr, CString, OsStr, OsString};
8use crate::os::unix::prelude::*;
9use crate::path::Path;
10use crate::sys::fd::FileDesc;
11use crate::sys::fs::File;
12#[cfg(not(target_os = "fuchsia"))]
13use crate::sys::fs::OpenOptions;
14use crate::sys::pipe::{self, AnonPipe};
15use crate::sys_common::process::{CommandEnv, CommandEnvs};
16use crate::sys_common::{FromInner, IntoInner};
17use crate::{fmt, io, ptr};
18
19cfg_if::cfg_if! {
20    if #[cfg(target_os = "fuchsia")] {
21        // fuchsia doesn't have /dev/null
22    } else if #[cfg(target_os = "redox")] {
23        const DEV_NULL: &CStr = c"null:";
24    } else if #[cfg(target_os = "vxworks")] {
25        const DEV_NULL: &CStr = c"/null";
26    } else {
27        const DEV_NULL: &CStr = c"/dev/null";
28    }
29}
30
31// Android with api less than 21 define sig* functions inline, so it is not
32// available for dynamic link. Implementing sigemptyset and sigaddset allow us
33// to support older Android version (independent of libc version).
34// The following implementations are based on
35// https://github.com/aosp-mirror/platform_bionic/blob/ad8dcd6023294b646e5a8288c0ed431b0845da49/libc/include/android/legacy_signal_inlines.h
36cfg_if::cfg_if! {
37    if #[cfg(target_os = "android")] {
38        #[allow(dead_code)]
39        pub unsafe fn sigemptyset(set: *mut libc::sigset_t) -> libc::c_int {
40            set.write_bytes(0u8, 1);
41            return 0;
42        }
43
44        #[allow(dead_code)]
45        pub unsafe fn sigaddset(set: *mut libc::sigset_t, signum: libc::c_int) -> libc::c_int {
46            use crate::slice;
47            use libc::{c_ulong, sigset_t};
48
49            // The implementations from bionic (android libc) type pun `sigset_t` as an
50            // array of `c_ulong`. This works, but lets add a smoke check to make sure
51            // that doesn't change.
52            const _: () = assert!(
53                align_of::<c_ulong>() == align_of::<sigset_t>()
54                    && (size_of::<sigset_t>() % size_of::<c_ulong>()) == 0
55            );
56
57            let bit = (signum - 1) as usize;
58            if set.is_null() || bit >= (8 * size_of::<sigset_t>()) {
59                crate::sys::pal::unix::os::set_errno(libc::EINVAL);
60                return -1;
61            }
62            let raw = slice::from_raw_parts_mut(
63                set as *mut c_ulong,
64                size_of::<sigset_t>() / size_of::<c_ulong>(),
65            );
66            const LONG_BIT: usize = size_of::<c_ulong>() * 8;
67            raw[bit / LONG_BIT] |= 1 << (bit % LONG_BIT);
68            return 0;
69        }
70    } else {
71        #[allow(unused_imports)]
72        pub use libc::{sigemptyset, sigaddset};
73    }
74}
75
76////////////////////////////////////////////////////////////////////////////////
77// Command
78////////////////////////////////////////////////////////////////////////////////
79
80pub struct Command {
81    program: CString,
82    args: Vec<CString>,
83    /// Exactly what will be passed to `execvp`.
84    ///
85    /// First element is a pointer to `program`, followed by pointers to
86    /// `args`, followed by a `null`. Be careful when modifying `program` or
87    /// `args` to properly update this as well.
88    argv: Argv,
89    env: CommandEnv,
90
91    program_kind: ProgramKind,
92    cwd: Option<CString>,
93    uid: Option<uid_t>,
94    gid: Option<gid_t>,
95    saw_nul: bool,
96    closures: Vec<Box<dyn FnMut() -> io::Result<()> + Send + Sync>>,
97    groups: Option<Box<[gid_t]>>,
98    stdin: Option<Stdio>,
99    stdout: Option<Stdio>,
100    stderr: Option<Stdio>,
101    #[cfg(target_os = "linux")]
102    create_pidfd: bool,
103    pgroup: Option<pid_t>,
104}
105
106// Create a new type for argv, so that we can make it `Send` and `Sync`
107struct Argv(Vec<*const c_char>);
108
109// It is safe to make `Argv` `Send` and `Sync`, because it contains
110// pointers to memory owned by `Command.args`
111unsafe impl Send for Argv {}
112unsafe impl Sync for Argv {}
113
114// passed back to std::process with the pipes connected to the child, if any
115// were requested
116pub struct StdioPipes {
117    pub stdin: Option<AnonPipe>,
118    pub stdout: Option<AnonPipe>,
119    pub stderr: Option<AnonPipe>,
120}
121
122// passed to do_exec() with configuration of what the child stdio should look
123// like
124#[cfg_attr(target_os = "vita", allow(dead_code))]
125pub struct ChildPipes {
126    pub stdin: ChildStdio,
127    pub stdout: ChildStdio,
128    pub stderr: ChildStdio,
129}
130
131pub enum ChildStdio {
132    Inherit,
133    Explicit(c_int),
134    Owned(FileDesc),
135
136    // On Fuchsia, null stdio is the default, so we simply don't specify
137    // any actions at the time of spawning.
138    #[cfg(target_os = "fuchsia")]
139    Null,
140}
141
142#[derive(Debug)]
143pub enum Stdio {
144    Inherit,
145    Null,
146    MakePipe,
147    Fd(FileDesc),
148    StaticFd(BorrowedFd<'static>),
149}
150
151#[derive(Copy, Clone, Debug, Eq, PartialEq)]
152pub enum ProgramKind {
153    /// A program that would be looked up on the PATH (e.g. `ls`)
154    PathLookup,
155    /// A relative path (e.g. `my-dir/foo`, `../foo`, `./foo`)
156    Relative,
157    /// An absolute path.
158    Absolute,
159}
160
161impl ProgramKind {
162    fn new(program: &OsStr) -> Self {
163        if program.as_encoded_bytes().starts_with(b"/") {
164            Self::Absolute
165        } else if program.as_encoded_bytes().contains(&b'/') {
166            // If the program has more than one component in it, it is a relative path.
167            Self::Relative
168        } else {
169            Self::PathLookup
170        }
171    }
172}
173
174impl Command {
175    #[cfg(not(target_os = "linux"))]
176    pub fn new(program: &OsStr) -> Command {
177        let mut saw_nul = false;
178        let program_kind = ProgramKind::new(program.as_ref());
179        let program = os2c(program, &mut saw_nul);
180        Command {
181            argv: Argv(vec![program.as_ptr(), ptr::null()]),
182            args: vec![program.clone()],
183            program,
184            program_kind,
185            env: Default::default(),
186            cwd: None,
187            uid: None,
188            gid: None,
189            saw_nul,
190            closures: Vec::new(),
191            groups: None,
192            stdin: None,
193            stdout: None,
194            stderr: None,
195            pgroup: None,
196        }
197    }
198
199    #[cfg(target_os = "linux")]
200    pub fn new(program: &OsStr) -> Command {
201        let mut saw_nul = false;
202        let program_kind = ProgramKind::new(program.as_ref());
203        let program = os2c(program, &mut saw_nul);
204        Command {
205            argv: Argv(vec![program.as_ptr(), ptr::null()]),
206            args: vec![program.clone()],
207            program,
208            program_kind,
209            env: Default::default(),
210            cwd: None,
211            uid: None,
212            gid: None,
213            saw_nul,
214            closures: Vec::new(),
215            groups: None,
216            stdin: None,
217            stdout: None,
218            stderr: None,
219            create_pidfd: false,
220            pgroup: None,
221        }
222    }
223
224    pub fn set_arg_0(&mut self, arg: &OsStr) {
225        // Set a new arg0
226        let arg = os2c(arg, &mut self.saw_nul);
227        debug_assert!(self.argv.0.len() > 1);
228        self.argv.0[0] = arg.as_ptr();
229        self.args[0] = arg;
230    }
231
232    pub fn arg(&mut self, arg: &OsStr) {
233        // Overwrite the trailing null pointer in `argv` and then add a new null
234        // pointer.
235        let arg = os2c(arg, &mut self.saw_nul);
236        self.argv.0[self.args.len()] = arg.as_ptr();
237        self.argv.0.push(ptr::null());
238
239        // Also make sure we keep track of the owned value to schedule a
240        // destructor for this memory.
241        self.args.push(arg);
242    }
243
244    pub fn cwd(&mut self, dir: &OsStr) {
245        self.cwd = Some(os2c(dir, &mut self.saw_nul));
246    }
247    pub fn uid(&mut self, id: uid_t) {
248        self.uid = Some(id);
249    }
250    pub fn gid(&mut self, id: gid_t) {
251        self.gid = Some(id);
252    }
253    pub fn groups(&mut self, groups: &[gid_t]) {
254        self.groups = Some(Box::from(groups));
255    }
256    pub fn pgroup(&mut self, pgroup: pid_t) {
257        self.pgroup = Some(pgroup);
258    }
259
260    #[cfg(target_os = "linux")]
261    pub fn create_pidfd(&mut self, val: bool) {
262        self.create_pidfd = val;
263    }
264
265    #[cfg(not(target_os = "linux"))]
266    #[allow(dead_code)]
267    pub fn get_create_pidfd(&self) -> bool {
268        false
269    }
270
271    #[cfg(target_os = "linux")]
272    pub fn get_create_pidfd(&self) -> bool {
273        self.create_pidfd
274    }
275
276    pub fn saw_nul(&self) -> bool {
277        self.saw_nul
278    }
279
280    pub fn get_program(&self) -> &OsStr {
281        OsStr::from_bytes(self.program.as_bytes())
282    }
283
284    #[allow(dead_code)]
285    pub fn get_program_kind(&self) -> ProgramKind {
286        self.program_kind
287    }
288
289    pub fn get_args(&self) -> CommandArgs<'_> {
290        let mut iter = self.args.iter();
291        iter.next();
292        CommandArgs { iter }
293    }
294
295    pub fn get_envs(&self) -> CommandEnvs<'_> {
296        self.env.iter()
297    }
298
299    pub fn get_current_dir(&self) -> Option<&Path> {
300        self.cwd.as_ref().map(|cs| Path::new(OsStr::from_bytes(cs.as_bytes())))
301    }
302
303    pub fn get_argv(&self) -> &Vec<*const c_char> {
304        &self.argv.0
305    }
306
307    pub fn get_program_cstr(&self) -> &CStr {
308        &*self.program
309    }
310
311    #[allow(dead_code)]
312    pub fn get_cwd(&self) -> Option<&CStr> {
313        self.cwd.as_deref()
314    }
315    #[allow(dead_code)]
316    pub fn get_uid(&self) -> Option<uid_t> {
317        self.uid
318    }
319    #[allow(dead_code)]
320    pub fn get_gid(&self) -> Option<gid_t> {
321        self.gid
322    }
323    #[allow(dead_code)]
324    pub fn get_groups(&self) -> Option<&[gid_t]> {
325        self.groups.as_deref()
326    }
327    #[allow(dead_code)]
328    pub fn get_pgroup(&self) -> Option<pid_t> {
329        self.pgroup
330    }
331
332    pub fn get_closures(&mut self) -> &mut Vec<Box<dyn FnMut() -> io::Result<()> + Send + Sync>> {
333        &mut self.closures
334    }
335
336    pub unsafe fn pre_exec(&mut self, f: Box<dyn FnMut() -> io::Result<()> + Send + Sync>) {
337        self.closures.push(f);
338    }
339
340    pub fn stdin(&mut self, stdin: Stdio) {
341        self.stdin = Some(stdin);
342    }
343
344    pub fn stdout(&mut self, stdout: Stdio) {
345        self.stdout = Some(stdout);
346    }
347
348    pub fn stderr(&mut self, stderr: Stdio) {
349        self.stderr = Some(stderr);
350    }
351
352    pub fn env_mut(&mut self) -> &mut CommandEnv {
353        &mut self.env
354    }
355
356    pub fn capture_env(&mut self) -> Option<CStringArray> {
357        let maybe_env = self.env.capture_if_changed();
358        maybe_env.map(|env| construct_envp(env, &mut self.saw_nul))
359    }
360
361    #[allow(dead_code)]
362    pub fn env_saw_path(&self) -> bool {
363        self.env.have_changed_path()
364    }
365
366    #[allow(dead_code)]
367    pub fn program_is_path(&self) -> bool {
368        self.program.to_bytes().contains(&b'/')
369    }
370
371    pub fn setup_io(
372        &self,
373        default: Stdio,
374        needs_stdin: bool,
375    ) -> io::Result<(StdioPipes, ChildPipes)> {
376        let null = Stdio::Null;
377        let default_stdin = if needs_stdin { &default } else { &null };
378        let stdin = self.stdin.as_ref().unwrap_or(default_stdin);
379        let stdout = self.stdout.as_ref().unwrap_or(&default);
380        let stderr = self.stderr.as_ref().unwrap_or(&default);
381        let (their_stdin, our_stdin) = stdin.to_child_stdio(true)?;
382        let (their_stdout, our_stdout) = stdout.to_child_stdio(false)?;
383        let (their_stderr, our_stderr) = stderr.to_child_stdio(false)?;
384        let ours = StdioPipes { stdin: our_stdin, stdout: our_stdout, stderr: our_stderr };
385        let theirs = ChildPipes { stdin: their_stdin, stdout: their_stdout, stderr: their_stderr };
386        Ok((ours, theirs))
387    }
388}
389
390fn os2c(s: &OsStr, saw_nul: &mut bool) -> CString {
391    CString::new(s.as_bytes()).unwrap_or_else(|_e| {
392        *saw_nul = true;
393        c"<string-with-nul>".to_owned()
394    })
395}
396
397// Helper type to manage ownership of the strings within a C-style array.
398pub struct CStringArray {
399    items: Vec<CString>,
400    ptrs: Vec<*const c_char>,
401}
402
403impl CStringArray {
404    pub fn with_capacity(capacity: usize) -> Self {
405        let mut result = CStringArray {
406            items: Vec::with_capacity(capacity),
407            ptrs: Vec::with_capacity(capacity + 1),
408        };
409        result.ptrs.push(ptr::null());
410        result
411    }
412    pub fn push(&mut self, item: CString) {
413        let l = self.ptrs.len();
414        self.ptrs[l - 1] = item.as_ptr();
415        self.ptrs.push(ptr::null());
416        self.items.push(item);
417    }
418    pub fn as_ptr(&self) -> *const *const c_char {
419        self.ptrs.as_ptr()
420    }
421}
422
423fn construct_envp(env: BTreeMap<OsString, OsString>, saw_nul: &mut bool) -> CStringArray {
424    let mut result = CStringArray::with_capacity(env.len());
425    for (mut k, v) in env {
426        // Reserve additional space for '=' and null terminator
427        k.reserve_exact(v.len() + 2);
428        k.push("=");
429        k.push(&v);
430
431        // Add the new entry into the array
432        if let Ok(item) = CString::new(k.into_vec()) {
433            result.push(item);
434        } else {
435            *saw_nul = true;
436        }
437    }
438
439    result
440}
441
442impl Stdio {
443    pub fn to_child_stdio(&self, readable: bool) -> io::Result<(ChildStdio, Option<AnonPipe>)> {
444        match *self {
445            Stdio::Inherit => Ok((ChildStdio::Inherit, None)),
446
447            // Make sure that the source descriptors are not an stdio
448            // descriptor, otherwise the order which we set the child's
449            // descriptors may blow away a descriptor which we are hoping to
450            // save. For example, suppose we want the child's stderr to be the
451            // parent's stdout, and the child's stdout to be the parent's
452            // stderr. No matter which we dup first, the second will get
453            // overwritten prematurely.
454            Stdio::Fd(ref fd) => {
455                if fd.as_raw_fd() >= 0 && fd.as_raw_fd() <= libc::STDERR_FILENO {
456                    Ok((ChildStdio::Owned(fd.duplicate()?), None))
457                } else {
458                    Ok((ChildStdio::Explicit(fd.as_raw_fd()), None))
459                }
460            }
461
462            Stdio::StaticFd(fd) => {
463                let fd = FileDesc::from_inner(fd.try_clone_to_owned()?);
464                Ok((ChildStdio::Owned(fd), None))
465            }
466
467            Stdio::MakePipe => {
468                let (reader, writer) = pipe::anon_pipe()?;
469                let (ours, theirs) = if readable { (writer, reader) } else { (reader, writer) };
470                Ok((ChildStdio::Owned(theirs.into_inner()), Some(ours)))
471            }
472
473            #[cfg(not(target_os = "fuchsia"))]
474            Stdio::Null => {
475                let mut opts = OpenOptions::new();
476                opts.read(readable);
477                opts.write(!readable);
478                let fd = File::open_c(DEV_NULL, &opts)?;
479                Ok((ChildStdio::Owned(fd.into_inner()), None))
480            }
481
482            #[cfg(target_os = "fuchsia")]
483            Stdio::Null => Ok((ChildStdio::Null, None)),
484        }
485    }
486}
487
488impl From<AnonPipe> for Stdio {
489    fn from(pipe: AnonPipe) -> Stdio {
490        Stdio::Fd(pipe.into_inner())
491    }
492}
493
494impl From<File> for Stdio {
495    fn from(file: File) -> Stdio {
496        Stdio::Fd(file.into_inner())
497    }
498}
499
500impl From<io::Stdout> for Stdio {
501    fn from(_: io::Stdout) -> Stdio {
502        // This ought really to be is Stdio::StaticFd(input_argument.as_fd()).
503        // But AsFd::as_fd takes its argument by reference, and yields
504        // a bounded lifetime, so it's no use here. There is no AsStaticFd.
505        //
506        // Additionally AsFd is only implemented for the *locked* versions.
507        // We don't want to lock them here.  (The implications of not locking
508        // are the same as those for process::Stdio::inherit().)
509        //
510        // Arguably the hypothetical AsStaticFd and AsFd<'static>
511        // should be implemented for io::Stdout, not just for StdoutLocked.
512        Stdio::StaticFd(unsafe { BorrowedFd::borrow_raw(libc::STDOUT_FILENO) })
513    }
514}
515
516impl From<io::Stderr> for Stdio {
517    fn from(_: io::Stderr) -> Stdio {
518        Stdio::StaticFd(unsafe { BorrowedFd::borrow_raw(libc::STDERR_FILENO) })
519    }
520}
521
522impl ChildStdio {
523    pub fn fd(&self) -> Option<c_int> {
524        match *self {
525            ChildStdio::Inherit => None,
526            ChildStdio::Explicit(fd) => Some(fd),
527            ChildStdio::Owned(ref fd) => Some(fd.as_raw_fd()),
528
529            #[cfg(target_os = "fuchsia")]
530            ChildStdio::Null => None,
531        }
532    }
533}
534
535impl fmt::Debug for Command {
536    // show all attributes but `self.closures` which does not implement `Debug`
537    // and `self.argv` which is not useful for debugging
538    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
539        if f.alternate() {
540            let mut debug_command = f.debug_struct("Command");
541            debug_command.field("program", &self.program).field("args", &self.args);
542            if !self.env.is_unchanged() {
543                debug_command.field("env", &self.env);
544            }
545
546            if self.cwd.is_some() {
547                debug_command.field("cwd", &self.cwd);
548            }
549            if self.uid.is_some() {
550                debug_command.field("uid", &self.uid);
551            }
552            if self.gid.is_some() {
553                debug_command.field("gid", &self.gid);
554            }
555
556            if self.groups.is_some() {
557                debug_command.field("groups", &self.groups);
558            }
559
560            if self.stdin.is_some() {
561                debug_command.field("stdin", &self.stdin);
562            }
563            if self.stdout.is_some() {
564                debug_command.field("stdout", &self.stdout);
565            }
566            if self.stderr.is_some() {
567                debug_command.field("stderr", &self.stderr);
568            }
569            if self.pgroup.is_some() {
570                debug_command.field("pgroup", &self.pgroup);
571            }
572
573            #[cfg(target_os = "linux")]
574            {
575                debug_command.field("create_pidfd", &self.create_pidfd);
576            }
577
578            debug_command.finish()
579        } else {
580            if let Some(ref cwd) = self.cwd {
581                write!(f, "cd {cwd:?} && ")?;
582            }
583            if self.env.does_clear() {
584                write!(f, "env -i ")?;
585                // Altered env vars will be printed next, that should exactly work as expected.
586            } else {
587                // Removed env vars need the command to be wrapped in `env`.
588                let mut any_removed = false;
589                for (key, value_opt) in self.get_envs() {
590                    if value_opt.is_none() {
591                        if !any_removed {
592                            write!(f, "env ")?;
593                            any_removed = true;
594                        }
595                        write!(f, "-u {} ", key.to_string_lossy())?;
596                    }
597                }
598            }
599            // Altered env vars can just be added in front of the program.
600            for (key, value_opt) in self.get_envs() {
601                if let Some(value) = value_opt {
602                    write!(f, "{}={value:?} ", key.to_string_lossy())?;
603                }
604            }
605            if self.program != self.args[0] {
606                write!(f, "[{:?}] ", self.program)?;
607            }
608            write!(f, "{:?}", self.args[0])?;
609
610            for arg in &self.args[1..] {
611                write!(f, " {:?}", arg)?;
612            }
613            Ok(())
614        }
615    }
616}
617
618#[derive(PartialEq, Eq, Clone, Copy)]
619pub struct ExitCode(u8);
620
621impl fmt::Debug for ExitCode {
622    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
623        f.debug_tuple("unix_exit_status").field(&self.0).finish()
624    }
625}
626
627impl ExitCode {
628    pub const SUCCESS: ExitCode = ExitCode(EXIT_SUCCESS as _);
629    pub const FAILURE: ExitCode = ExitCode(EXIT_FAILURE as _);
630
631    #[inline]
632    pub fn as_i32(&self) -> i32 {
633        self.0 as i32
634    }
635}
636
637impl From<u8> for ExitCode {
638    fn from(code: u8) -> Self {
639        Self(code)
640    }
641}
642
643pub struct CommandArgs<'a> {
644    iter: crate::slice::Iter<'a, CString>,
645}
646
647impl<'a> Iterator for CommandArgs<'a> {
648    type Item = &'a OsStr;
649    fn next(&mut self) -> Option<&'a OsStr> {
650        self.iter.next().map(|cs| OsStr::from_bytes(cs.as_bytes()))
651    }
652    fn size_hint(&self) -> (usize, Option<usize>) {
653        self.iter.size_hint()
654    }
655}
656
657impl<'a> ExactSizeIterator for CommandArgs<'a> {
658    fn len(&self) -> usize {
659        self.iter.len()
660    }
661    fn is_empty(&self) -> bool {
662        self.iter.is_empty()
663    }
664}
665
666impl<'a> fmt::Debug for CommandArgs<'a> {
667    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
668        f.debug_list().entries(self.iter.clone()).finish()
669    }
670}