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

std/sys/process/unix/
common.rs
