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::process::StdioPipes;
13use crate::sys::fd::FileDesc;
14use crate::sys::fs::File;
15#[cfg(not(any(target_os = "fuchsia", target_os = "l4re")))]
16use crate::sys::fs::OpenOptions;
17use crate::sys::pipe::pipe;
18use crate::sys::process::env::{CommandEnv, CommandEnvs, CommandResolvedEnvs};
19use crate::sys::{FromInner, IntoInner, cvt_r};
20use crate::{fmt, io, mem};
21
22mod cstring_array;
23
24cfg_select! {
25    target_os = "fuchsia" => {
26        // fuchsia doesn't have /dev/null
27    },
28    target_os = "l4re" => {
29        // l4re doesn't have /dev/null
30    }
31    target_os = "vxworks" => {
32        const DEV_NULL: &CStr = c"/null";
33    }
34    _ => {
35        const DEV_NULL: &CStr = c"/dev/null";
36    }
37}
38
39// Android with api less than 21 define sig* functions inline, so it is not
40// available for dynamic link. Implementing sigemptyset and sigaddset allow us
41// to support older Android version (independent of libc version).
42// The following implementations are based on
43// https://github.com/aosp-mirror/platform_bionic/blob/ad8dcd6023294b646e5a8288c0ed431b0845da49/libc/include/android/legacy_signal_inlines.h
44cfg_select! {
45    target_os = "android" => {
46        #[allow(dead_code)]
47        pub unsafe fn sigemptyset(set: *mut libc::sigset_t) -> libc::c_int {
48            set.write_bytes(0u8, 1);
49            return 0;
50        }
51
52        #[allow(dead_code)]
53        pub unsafe fn sigaddset(set: *mut libc::sigset_t, signum: libc::c_int) -> libc::c_int {
54            use crate::slice;
55            use libc::{c_ulong, sigset_t};
56
57            // The implementations from bionic (android libc) type pun `sigset_t` as an
58            // array of `c_ulong`. This works, but lets add a smoke check to make sure
59            // that doesn't change.
60            const _: () = assert!(
61                align_of::<c_ulong>() == align_of::<sigset_t>()
62                    && (size_of::<sigset_t>() % size_of::<c_ulong>()) == 0
63            );
64
65            let bit = (signum - 1) as usize;
66            if set.is_null() || bit >= (8 * size_of::<sigset_t>()) {
67                crate::sys::io::set_errno(libc::EINVAL);
68                return -1;
69            }
70            let raw = slice::from_raw_parts_mut(
71                set as *mut c_ulong,
72                size_of::<sigset_t>() / size_of::<c_ulong>(),
73            );
74            const LONG_BIT: usize = size_of::<c_ulong>() * 8;
75            raw[bit / LONG_BIT] |= 1 << (bit % LONG_BIT);
76            return 0;
77        }
78    }
79    _ => {
80        #[allow(unused_imports)]
81        pub use libc::{sigemptyset, sigaddset};
82    }
83}
84
85////////////////////////////////////////////////////////////////////////////////
86// Command
87////////////////////////////////////////////////////////////////////////////////
88
89pub struct Command {
90    program: CString,
91    args: CStringArray,
92    env: CommandEnv,
93
94    program_kind: ProgramKind,
95    cwd: Option<CString>,
96    chroot: Option<CString>,
97    uid: Option<uid_t>,
98    gid: Option<gid_t>,
99    saw_nul: bool,
100    closures: Vec<Box<dyn FnMut() -> io::Result<()> + Send + Sync>>,
101    groups: Option<Box<[gid_t]>>,
102    stdin: Option<Stdio>,
103    stdout: Option<Stdio>,
104    stderr: Option<Stdio>,
105    #[cfg(target_os = "linux")]
106    create_pidfd: bool,
107    pgroup: Option<pid_t>,
108    setsid: bool,
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 and L4Re, null stdio is the default, so we simply don't
126    // specify any actions at the time of spawning.
127    #[cfg(any(target_os = "fuchsia", target_os = "l4re"))]
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            setsid: false,
189        }
190    }
191
192    pub fn set_arg_0(&mut self, arg: &OsStr) {
193        // Set a new arg0
194        let arg = os2c(arg, &mut self.saw_nul);
195        self.args.write(0, arg);
196    }
197
198    pub fn arg(&mut self, arg: &OsStr) {
199        let arg = os2c(arg, &mut self.saw_nul);
200        self.args.push(arg);
201    }
202
203    pub fn cwd(&mut self, dir: &OsStr) {
204        self.cwd = Some(os2c(dir, &mut self.saw_nul));
205    }
206    pub fn uid(&mut self, id: uid_t) {
207        self.uid = Some(id);
208    }
209    pub fn gid(&mut self, id: gid_t) {
210        self.gid = Some(id);
211    }
212    pub fn groups(&mut self, groups: &[gid_t]) {
213        self.groups = Some(Box::from(groups));
214    }
215    pub fn pgroup(&mut self, pgroup: pid_t) {
216        self.pgroup = Some(pgroup);
217    }
218    pub fn chroot(&mut self, dir: &Path) {
219        self.chroot = Some(os2c(dir.as_os_str(), &mut self.saw_nul));
220        if self.cwd.is_none() {
221            self.cwd(OsStr::new("/"));
222        }
223    }
224    pub fn setsid(&mut self, setsid: bool) {
225        self.setsid = setsid;
226    }
227
228    #[cfg(target_os = "linux")]
229    pub fn create_pidfd(&mut self, val: bool) {
230        self.create_pidfd = val;
231    }
232
233    #[cfg(not(target_os = "linux"))]
234    #[allow(dead_code)]
235    pub fn get_create_pidfd(&self) -> bool {
236        false
237    }
238
239    #[cfg(target_os = "linux")]
240    pub fn get_create_pidfd(&self) -> bool {
241        self.create_pidfd
242    }
243
244    pub fn saw_nul(&self) -> bool {
245        self.saw_nul
246    }
247
248    pub fn get_program(&self) -> &OsStr {
249        OsStr::from_bytes(self.program.as_bytes())
250    }
251
252    #[allow(dead_code)]
253    pub fn get_program_kind(&self) -> ProgramKind {
254        self.program_kind
255    }
256
257    pub fn get_args(&self) -> CommandArgs<'_> {
258        let mut iter = self.args.iter();
259        // argv[0] contains the program name, but we are only interested in the
260        // arguments so skip it.
261        iter.next();
262        CommandArgs { iter }
263    }
264
265    pub fn get_envs(&self) -> CommandEnvs<'_> {
266        self.env.iter()
267    }
268
269    pub fn get_env_clear(&self) -> bool {
270        self.env.does_clear()
271    }
272
273    pub fn get_resolved_envs(&self) -> CommandResolvedEnvs {
274        CommandResolvedEnvs::new(self.env.capture())
275    }
276
277    pub fn get_current_dir(&self) -> Option<&Path> {
278        self.cwd.as_ref().map(|cs| Path::new(OsStr::from_bytes(cs.as_bytes())))
279    }
280
281    pub fn get_argv(&self) -> &CStringArray {
282        &self.args
283    }
284
285    pub fn get_program_cstr(&self) -> &CStr {
286        &self.program
287    }
288
289    #[allow(dead_code)]
290    pub fn get_cwd(&self) -> Option<&CStr> {
291        self.cwd.as_deref()
292    }
293    #[allow(dead_code)]
294    pub fn get_uid(&self) -> Option<uid_t> {
295        self.uid
296    }
297    #[allow(dead_code)]
298    pub fn get_gid(&self) -> Option<gid_t> {
299        self.gid
300    }
301    #[allow(dead_code)]
302    pub fn get_groups(&self) -> Option<&[gid_t]> {
303        self.groups.as_deref()
304    }
305    #[allow(dead_code)]
306    pub fn get_pgroup(&self) -> Option<pid_t> {
307        self.pgroup
308    }
309    #[allow(dead_code)]
310    pub fn get_chroot(&self) -> Option<&CStr> {
311        self.chroot.as_deref()
312    }
313    #[allow(dead_code)]
314    pub fn get_setsid(&self) -> bool {
315        self.setsid
316    }
317
318    pub fn get_closures(&mut self) -> &mut Vec<Box<dyn FnMut() -> io::Result<()> + Send + Sync>> {
319        &mut self.closures
320    }
321
322    pub unsafe fn pre_exec(&mut self, f: Box<dyn FnMut() -> io::Result<()> + Send + Sync>) {
323        self.closures.push(f);
324    }
325
326    pub fn stdin(&mut self, stdin: Stdio) {
327        self.stdin = Some(stdin);
328    }
329
330    pub fn stdout(&mut self, stdout: Stdio) {
331        self.stdout = Some(stdout);
332    }
333
334    pub fn stderr(&mut self, stderr: Stdio) {
335        self.stderr = Some(stderr);
336    }
337
338    pub fn env_mut(&mut self) -> &mut CommandEnv {
339        &mut self.env
340    }
341
342    pub fn capture_env(&mut self) -> Option<CStringArray> {
343        let maybe_env = self.env.capture_if_changed();
344        maybe_env.map(|env| construct_envp(env, &mut self.saw_nul))
345    }
346
347    #[allow(dead_code)]
348    pub fn env_saw_path(&self) -> bool {
349        self.env.have_changed_path()
350    }
351
352    #[allow(dead_code)]
353    pub fn program_is_path(&self) -> bool {
354        self.program.to_bytes().contains(&b'/')
355    }
356
357    pub fn setup_io(
358        &self,
359        default: Stdio,
360        needs_stdin: bool,
361    ) -> io::Result<(StdioPipes, ChildPipes)> {
362        let null = Stdio::Null;
363        let default_stdin = if needs_stdin { &default } else { &null };
364        let stdin = self.stdin.as_ref().unwrap_or(default_stdin);
365        let stdout = self.stdout.as_ref().unwrap_or(&default);
366        let stderr = self.stderr.as_ref().unwrap_or(&default);
367        let (their_stdin, our_stdin) = stdin.to_child_stdio(true)?;
368        let (their_stdout, our_stdout) = stdout.to_child_stdio(false)?;
369        let (their_stderr, our_stderr) = stderr.to_child_stdio(false)?;
370        let ours = StdioPipes { stdin: our_stdin, stdout: our_stdout, stderr: our_stderr };
371        let theirs = ChildPipes { stdin: their_stdin, stdout: their_stdout, stderr: their_stderr };
372        Ok((ours, theirs))
373    }
374}
375
376fn os2c(s: &OsStr, saw_nul: &mut bool) -> CString {
377    CString::new(s.as_bytes()).unwrap_or_else(|_e| {
378        *saw_nul = true;
379        c"<string-with-nul>".to_owned()
380    })
381}
382
383fn construct_envp(env: BTreeMap<OsString, OsString>, saw_nul: &mut bool) -> CStringArray {
384    let mut result = CStringArray::with_capacity(env.len());
385    for (mut k, v) in env {
386        // Reserve additional space for '=' and null terminator
387        k.reserve_exact(v.len() + 2);
388        k.push("=");
389        k.push(&v);
390
391        // Add the new entry into the array
392        if let Ok(item) = CString::new(k.into_vec()) {
393            result.push(item);
394        } else {
395            *saw_nul = true;
396        }
397    }
398
399    result
400}
401
402impl Stdio {
403    pub fn to_child_stdio(&self, readable: bool) -> io::Result<(ChildStdio, Option<ChildPipe>)> {
404        match *self {
405            Stdio::Inherit => Ok((ChildStdio::Inherit, None)),
406
407            // Make sure that the source descriptors are not an stdio
408            // descriptor, otherwise the order which we set the child's
409            // descriptors may blow away a descriptor which we are hoping to
410            // save. For example, suppose we want the child's stderr to be the
411            // parent's stdout, and the child's stdout to be the parent's
412            // stderr. No matter which we dup first, the second will get
413            // overwritten prematurely.
414            Stdio::Fd(ref fd) => {
415                if fd.as_raw_fd() >= 0 && fd.as_raw_fd() <= libc::STDERR_FILENO {
416                    Ok((ChildStdio::Owned(fd.duplicate()?), None))
417                } else {
418                    Ok((ChildStdio::Explicit(fd.as_raw_fd()), None))
419                }
420            }
421
422            Stdio::StaticFd(fd) => {
423                let fd = FileDesc::from_inner(fd.try_clone_to_owned()?);
424                Ok((ChildStdio::Owned(fd), None))
425            }
426
427            Stdio::MakePipe => {
428                let (reader, writer) = pipe()?;
429                let (ours, theirs) = if readable { (writer, reader) } else { (reader, writer) };
430                Ok((ChildStdio::Owned(theirs), Some(ours)))
431            }
432
433            #[cfg(not(any(target_os = "fuchsia", target_os = "l4re")))]
434            Stdio::Null => {
435                let mut opts = OpenOptions::new();
436                opts.read(readable);
437                opts.write(!readable);
438                let fd = File::open_c(DEV_NULL, &opts)?;
439                Ok((ChildStdio::Owned(fd.into_inner()), None))
440            }
441
442            #[cfg(any(target_os = "fuchsia", target_os = "l4re"))]
443            Stdio::Null => Ok((ChildStdio::Null, None)),
444        }
445    }
446}
447
448impl From<FileDesc> for Stdio {
449    fn from(fd: FileDesc) -> Stdio {
450        Stdio::Fd(fd)
451    }
452}
453
454impl From<File> for Stdio {
455    fn from(file: File) -> Stdio {
456        Stdio::Fd(file.into_inner())
457    }
458}
459
460impl From<io::Stdout> for Stdio {
461    fn from(_: io::Stdout) -> Stdio {
462        // This ought really to be is Stdio::StaticFd(input_argument.as_fd()).
463        // But AsFd::as_fd takes its argument by reference, and yields
464        // a bounded lifetime, so it's no use here. There is no AsStaticFd.
465        //
466        // Additionally AsFd is only implemented for the *locked* versions.
467        // We don't want to lock them here.  (The implications of not locking
468        // are the same as those for process::Stdio::inherit().)
469        //
470        // Arguably the hypothetical AsStaticFd and AsFd<'static>
471        // should be implemented for io::Stdout, not just for StdoutLocked.
472        Stdio::StaticFd(unsafe { BorrowedFd::borrow_raw(libc::STDOUT_FILENO) })
473    }
474}
475
476impl From<io::Stderr> for Stdio {
477    fn from(_: io::Stderr) -> Stdio {
478        Stdio::StaticFd(unsafe { BorrowedFd::borrow_raw(libc::STDERR_FILENO) })
479    }
480}
481
482impl ChildStdio {
483    pub fn fd(&self) -> Option<c_int> {
484        match *self {
485            ChildStdio::Inherit => None,
486            ChildStdio::Explicit(fd) => Some(fd),
487            ChildStdio::Owned(ref fd) => Some(fd.as_raw_fd()),
488
489            #[cfg(any(target_os = "fuchsia", target_os = "l4re"))]
490            ChildStdio::Null => None,
491        }
492    }
493}
494
495impl fmt::Debug for Command {
496    // show all attributes but `self.closures` which does not implement `Debug`
497    // and `self.argv` which is not useful for debugging
498    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
499        if f.alternate() {
500            let mut debug_command = f.debug_struct("Command");
501            debug_command.field("program", &self.program).field("args", &self.args);
502            if !self.env.is_unchanged() {
503                debug_command.field("env", &self.env);
504            }
505
506            if self.cwd.is_some() {
507                debug_command.field("cwd", &self.cwd);
508            }
509            if self.uid.is_some() {
510                debug_command.field("uid", &self.uid);
511            }
512            if self.gid.is_some() {
513                debug_command.field("gid", &self.gid);
514            }
515
516            if self.groups.is_some() {
517                debug_command.field("groups", &self.groups);
518            }
519
520            if self.stdin.is_some() {
521                debug_command.field("stdin", &self.stdin);
522            }
523            if self.stdout.is_some() {
524                debug_command.field("stdout", &self.stdout);
525            }
526            if self.stderr.is_some() {
527                debug_command.field("stderr", &self.stderr);
528            }
529            if self.pgroup.is_some() {
530                debug_command.field("pgroup", &self.pgroup);
531            }
532
533            #[cfg(target_os = "linux")]
534            {
535                debug_command.field("create_pidfd", &self.create_pidfd);
536            }
537
538            debug_command.finish()
539        } else {
540            if let Some(ref cwd) = self.cwd {
541                write!(f, "cd {cwd:?} && ")?;
542            }
543            if self.env.does_clear() {
544                write!(f, "env -i ")?;
545                // Altered env vars will be printed next, that should exactly work as expected.
546            } else {
547                // Removed env vars need the command to be wrapped in `env`.
548                let mut any_removed = false;
549                for (key, value_opt) in self.get_envs() {
550                    if value_opt.is_none() {
551                        if !any_removed {
552                            write!(f, "env ")?;
553                            any_removed = true;
554                        }
555                        write!(f, "-u {} ", key.to_string_lossy())?;
556                    }
557                }
558            }
559            // Altered env vars can just be added in front of the program.
560            for (key, value_opt) in self.get_envs() {
561                if let Some(value) = value_opt {
562                    write!(f, "{}={value:?} ", key.to_string_lossy())?;
563                }
564            }
565
566            if *self.program != self.args[0] {
567                write!(f, "[{:?}] ", self.program)?;
568            }
569            write!(f, "{:?}", &self.args[0])?;
570
571            for arg in self.get_args() {
572                write!(f, " {:?}", arg)?;
573            }
574
575            Ok(())
576        }
577    }
578}
579
580#[derive(PartialEq, Eq, Clone, Copy)]
581pub struct ExitCode(u8);
582
583impl fmt::Debug for ExitCode {
584    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
585        f.debug_tuple("unix_exit_status").field(&self.0).finish()
586    }
587}
588
589impl ExitCode {
590    pub const SUCCESS: ExitCode = ExitCode(EXIT_SUCCESS as _);
591    pub const FAILURE: ExitCode = ExitCode(EXIT_FAILURE as _);
592
593    #[inline]
594    pub fn as_i32(&self) -> i32 {
595        self.0 as i32
596    }
597}
598
599impl From<u8> for ExitCode {
600    fn from(code: u8) -> Self {
601        Self(code)
602    }
603}
604
605pub struct CommandArgs<'a> {
606    iter: CStringIter<'a>,
607}
608
609impl<'a> Iterator for CommandArgs<'a> {
610    type Item = &'a OsStr;
611
612    fn next(&mut self) -> Option<&'a OsStr> {
613        self.iter.next().map(|cs| OsStr::from_bytes(cs.to_bytes()))
614    }
615
616    fn size_hint(&self) -> (usize, Option<usize>) {
617        self.iter.size_hint()
618    }
619}
620
621impl<'a> ExactSizeIterator for CommandArgs<'a> {
622    fn len(&self) -> usize {
623        self.iter.len()
624    }
625
626    fn is_empty(&self) -> bool {
627        self.iter.is_empty()
628    }
629}
630
631impl<'a> fmt::Debug for CommandArgs<'a> {
632    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
633        f.debug_list().entries(self.iter.clone()).finish()
634    }
635}
636
637pub type ChildPipe = crate::sys::pipe::Pipe;
638
639pub fn read_output(
640    out: ChildPipe,
641    stdout: &mut Vec<u8>,
642    err: ChildPipe,
643    stderr: &mut Vec<u8>,
644) -> io::Result<()> {
645    // Set both pipes into nonblocking mode as we're gonna be reading from both
646    // in the `select` loop below, and we wouldn't want one to block the other!
647    out.set_nonblocking(true)?;
648    err.set_nonblocking(true)?;
649
650    let mut fds: [libc::pollfd; 2] = unsafe { mem::zeroed() };
651    fds[0].fd = out.as_raw_fd();
652    fds[0].events = libc::POLLIN;
653    fds[1].fd = err.as_raw_fd();
654    fds[1].events = libc::POLLIN;
655    loop {
656        // wait for either pipe to become readable using `poll`
657        cvt_r(|| unsafe { libc::poll(fds.as_mut_ptr(), 2, -1) })?;
658
659        if fds[0].revents != 0 && read(&out, stdout)? {
660            err.set_nonblocking(false)?;
661            return err.read_to_end(stderr).map(drop);
662        }
663        if fds[1].revents != 0 && read(&err, stderr)? {
664            out.set_nonblocking(false)?;
665            return out.read_to_end(stdout).map(drop);
666        }
667    }
668
669    // Read as much as we can from each pipe, ignoring EWOULDBLOCK or
670    // EAGAIN. If we hit EOF, then this will happen because the underlying
671    // reader will return Ok(0), in which case we'll see `Ok` ourselves. In
672    // this case we flip the other fd back into blocking mode and read
673    // whatever's leftover on that file descriptor.
674    fn read(fd: &FileDesc, dst: &mut Vec<u8>) -> Result<bool, io::Error> {
675        match fd.read_to_end(dst) {
676            Ok(_) => Ok(true),
677            Err(e) => {
678                if e.raw_os_error() == Some(libc::EWOULDBLOCK)
679                    || e.raw_os_error() == Some(libc::EAGAIN)
680                {
681                    Ok(false)
682                } else {
683                    Err(e)
684                }
685            }
686        }
687    }
688}
689
690pub fn getpid() -> u32 {
691    unsafe { libc::getpid() as u32 }
692}
693
694pub fn getppid() -> u32 {
695    unsafe { libc::getppid() as u32 }
696}
std/sys/process/unix/common.rs

std/sys/process/unix/
common.rs
