std/sys/process/unix/
common.rs

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