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

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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::{
47                mem::{align_of, size_of},
48                slice,
49            };
50            use libc::{c_ulong, sigset_t};
51
52            // The implementations from bionic (android libc) type pun `sigset_t` as an
53            // array of `c_ulong`. This works, but lets add a smoke check to make sure
54            // that doesn't change.
55            const _: () = assert!(
56                align_of::<c_ulong>() == align_of::<sigset_t>()
57                    && (size_of::<sigset_t>() % size_of::<c_ulong>()) == 0
58            );
59
60            let bit = (signum - 1) as usize;
61            if set.is_null() || bit >= (8 * size_of::<sigset_t>()) {
62                crate::sys::pal::unix::os::set_errno(libc::EINVAL);
63                return -1;
64            }
65            let raw = slice::from_raw_parts_mut(
66                set as *mut c_ulong,
67                size_of::<sigset_t>() / size_of::<c_ulong>(),
68            );
69            const LONG_BIT: usize = size_of::<c_ulong>() * 8;
70            raw[bit / LONG_BIT] |= 1 << (bit % LONG_BIT);
71            return 0;
72        }
73    } else {
74        #[allow(unused_imports)]
75        pub use libc::{sigemptyset, sigaddset};
76    }
77}
78
79////////////////////////////////////////////////////////////////////////////////
80// Command
81////////////////////////////////////////////////////////////////////////////////
82
83pub struct Command {
84    program: CString,
85    args: Vec<CString>,
86    /// Exactly what will be passed to `execvp`.
87    ///
88    /// First element is a pointer to `program`, followed by pointers to
89    /// `args`, followed by a `null`. Be careful when modifying `program` or
90    /// `args` to properly update this as well.
91    argv: Argv,
92    env: CommandEnv,
93
94    program_kind: ProgramKind,
95    cwd: Option<CString>,
96    uid: Option<uid_t>,
97    gid: Option<gid_t>,
98    saw_nul: bool,
99    closures: Vec<Box<dyn FnMut() -> io::Result<()> + Send + Sync>>,
100    groups: Option<Box<[gid_t]>>,
101    stdin: Option<Stdio>,
102    stdout: Option<Stdio>,
103    stderr: Option<Stdio>,
104    #[cfg(target_os = "linux")]
105    create_pidfd: bool,
106    pgroup: Option<pid_t>,
107}
108
109// Create a new type for argv, so that we can make it `Send` and `Sync`
110struct Argv(Vec<*const c_char>);
111
112// It is safe to make `Argv` `Send` and `Sync`, because it contains
113// pointers to memory owned by `Command.args`
114unsafe impl Send for Argv {}
115unsafe impl Sync for Argv {}
116
117// passed back to std::process with the pipes connected to the child, if any
118// were requested
119pub struct StdioPipes {
120    pub stdin: Option<AnonPipe>,
121    pub stdout: Option<AnonPipe>,
122    pub stderr: Option<AnonPipe>,
123}
124
125// passed to do_exec() with configuration of what the child stdio should look
126// like
127#[cfg_attr(target_os = "vita", allow(dead_code))]
128pub struct ChildPipes {
129    pub stdin: ChildStdio,
130    pub stdout: ChildStdio,
131    pub stderr: ChildStdio,
132}
133
134pub enum ChildStdio {
135    Inherit,
136    Explicit(c_int),
137    Owned(FileDesc),
138
139    // On Fuchsia, null stdio is the default, so we simply don't specify
140    // any actions at the time of spawning.
141    #[cfg(target_os = "fuchsia")]
142    Null,
143}
144
145#[derive(Debug)]
146pub enum Stdio {
147    Inherit,
148    Null,
149    MakePipe,
150    Fd(FileDesc),
151    StaticFd(BorrowedFd<'static>),
152}
153
154#[derive(Copy, Clone, Debug, Eq, PartialEq)]
155pub enum ProgramKind {
156    /// A program that would be looked up on the PATH (e.g. `ls`)
157    PathLookup,
158    /// A relative path (e.g. `my-dir/foo`, `../foo`, `./foo`)
159    Relative,
160    /// An absolute path.
161    Absolute,
162}
163
164impl ProgramKind {
165    fn new(program: &OsStr) -> Self {
166        if program.as_encoded_bytes().starts_with(b"/") {
167            Self::Absolute
168        } else if program.as_encoded_bytes().contains(&b'/') {
169            // If the program has more than one component in it, it is a relative path.
170            Self::Relative
171        } else {
172            Self::PathLookup
173        }
174    }
175}
176
177impl Command {
178    #[cfg(not(target_os = "linux"))]
179    pub fn new(program: &OsStr) -> Command {
180        let mut saw_nul = false;
181        let program_kind = ProgramKind::new(program.as_ref());
182        let program = os2c(program, &mut saw_nul);
183        Command {
184            argv: Argv(vec![program.as_ptr(), ptr::null()]),
185            args: vec![program.clone()],
186            program,
187            program_kind,
188            env: Default::default(),
189            cwd: None,
190            uid: None,
191            gid: None,
192            saw_nul,
193            closures: Vec::new(),
194            groups: None,
195            stdin: None,
196            stdout: None,
197            stderr: None,
198            pgroup: None,
199        }
200    }
201
202    #[cfg(target_os = "linux")]
203    pub fn new(program: &OsStr) -> Command {
204        let mut saw_nul = false;
205        let program_kind = ProgramKind::new(program.as_ref());
206        let program = os2c(program, &mut saw_nul);
207        Command {
208            argv: Argv(vec![program.as_ptr(), ptr::null()]),
209            args: vec![program.clone()],
210            program,
211            program_kind,
212            env: Default::default(),
213            cwd: None,
214            uid: None,
215            gid: None,
216            saw_nul,
217            closures: Vec::new(),
218            groups: None,
219            stdin: None,
220            stdout: None,
221            stderr: None,
222            create_pidfd: false,
223            pgroup: None,
224        }
225    }
226
227    pub fn set_arg_0(&mut self, arg: &OsStr) {
228        // Set a new arg0
229        let arg = os2c(arg, &mut self.saw_nul);
230        debug_assert!(self.argv.0.len() > 1);
231        self.argv.0[0] = arg.as_ptr();
232        self.args[0] = arg;
233    }
234
235    pub fn arg(&mut self, arg: &OsStr) {
236        // Overwrite the trailing null pointer in `argv` and then add a new null
237        // pointer.
238        let arg = os2c(arg, &mut self.saw_nul);
239        self.argv.0[self.args.len()] = arg.as_ptr();
240        self.argv.0.push(ptr::null());
241
242        // Also make sure we keep track of the owned value to schedule a
243        // destructor for this memory.
244        self.args.push(arg);
245    }
246
247    pub fn cwd(&mut self, dir: &OsStr) {
248        self.cwd = Some(os2c(dir, &mut self.saw_nul));
249    }
250    pub fn uid(&mut self, id: uid_t) {
251        self.uid = Some(id);
252    }
253    pub fn gid(&mut self, id: gid_t) {
254        self.gid = Some(id);
255    }
256    pub fn groups(&mut self, groups: &[gid_t]) {
257        self.groups = Some(Box::from(groups));
258    }
259    pub fn pgroup(&mut self, pgroup: pid_t) {
260        self.pgroup = Some(pgroup);
261    }
262
263    #[cfg(target_os = "linux")]
264    pub fn create_pidfd(&mut self, val: bool) {
265        self.create_pidfd = val;
266    }
267
268    #[cfg(not(target_os = "linux"))]
269    #[allow(dead_code)]
270    pub fn get_create_pidfd(&self) -> bool {
271        false
272    }
273
274    #[cfg(target_os = "linux")]
275    pub fn get_create_pidfd(&self) -> bool {
276        self.create_pidfd
277    }
278
279    pub fn saw_nul(&self) -> bool {
280        self.saw_nul
281    }
282
283    pub fn get_program(&self) -> &OsStr {
284        OsStr::from_bytes(self.program.as_bytes())
285    }
286
287    #[allow(dead_code)]
288    pub fn get_program_kind(&self) -> ProgramKind {
289        self.program_kind
290    }
291
292    pub fn get_args(&self) -> CommandArgs<'_> {
293        let mut iter = self.args.iter();
294        iter.next();
295        CommandArgs { iter }
296    }
297
298    pub fn get_envs(&self) -> CommandEnvs<'_> {
299        self.env.iter()
300    }
301
302    pub fn get_current_dir(&self) -> Option<&Path> {
303        self.cwd.as_ref().map(|cs| Path::new(OsStr::from_bytes(cs.as_bytes())))
304    }
305
306    pub fn get_argv(&self) -> &Vec<*const c_char> {
307        &self.argv.0
308    }
309
310    pub fn get_program_cstr(&self) -> &CStr {
311        &*self.program
312    }
313
314    #[allow(dead_code)]
315    pub fn get_cwd(&self) -> Option<&CStr> {
316        self.cwd.as_deref()
317    }
318    #[allow(dead_code)]
319    pub fn get_uid(&self) -> Option<uid_t> {
320        self.uid
321    }
322    #[allow(dead_code)]
323    pub fn get_gid(&self) -> Option<gid_t> {
324        self.gid
325    }
326    #[allow(dead_code)]
327    pub fn get_groups(&self) -> Option<&[gid_t]> {
328        self.groups.as_deref()
329    }
330    #[allow(dead_code)]
331    pub fn get_pgroup(&self) -> Option<pid_t> {
332        self.pgroup
333    }
334
335    pub fn get_closures(&mut self) -> &mut Vec<Box<dyn FnMut() -> io::Result<()> + Send + Sync>> {
336        &mut self.closures
337    }
338
339    pub unsafe fn pre_exec(&mut self, f: Box<dyn FnMut() -> io::Result<()> + Send + Sync>) {
340        self.closures.push(f);
341    }
342
343    pub fn stdin(&mut self, stdin: Stdio) {
344        self.stdin = Some(stdin);
345    }
346
347    pub fn stdout(&mut self, stdout: Stdio) {
348        self.stdout = Some(stdout);
349    }
350
351    pub fn stderr(&mut self, stderr: Stdio) {
352        self.stderr = Some(stderr);
353    }
354
355    pub fn env_mut(&mut self) -> &mut CommandEnv {
356        &mut self.env
357    }
358
359    pub fn capture_env(&mut self) -> Option<CStringArray> {
360        let maybe_env = self.env.capture_if_changed();
361        maybe_env.map(|env| construct_envp(env, &mut self.saw_nul))
362    }
363
364    #[allow(dead_code)]
365    pub fn env_saw_path(&self) -> bool {
366        self.env.have_changed_path()
367    }
368
369    #[allow(dead_code)]
370    pub fn program_is_path(&self) -> bool {
371        self.program.to_bytes().contains(&b'/')
372    }
373
374    pub fn setup_io(
375        &self,
376        default: Stdio,
377        needs_stdin: bool,
378    ) -> io::Result<(StdioPipes, ChildPipes)> {
379        let null = Stdio::Null;
380        let default_stdin = if needs_stdin { &default } else { &null };
381        let stdin = self.stdin.as_ref().unwrap_or(default_stdin);
382        let stdout = self.stdout.as_ref().unwrap_or(&default);
383        let stderr = self.stderr.as_ref().unwrap_or(&default);
384        let (their_stdin, our_stdin) = stdin.to_child_stdio(true)?;
385        let (their_stdout, our_stdout) = stdout.to_child_stdio(false)?;
386        let (their_stderr, our_stderr) = stderr.to_child_stdio(false)?;
387        let ours = StdioPipes { stdin: our_stdin, stdout: our_stdout, stderr: our_stderr };
388        let theirs = ChildPipes { stdin: their_stdin, stdout: their_stdout, stderr: their_stderr };
389        Ok((ours, theirs))
390    }
391}
392
393fn os2c(s: &OsStr, saw_nul: &mut bool) -> CString {
394    CString::new(s.as_bytes()).unwrap_or_else(|_e| {
395        *saw_nul = true;
396        c"<string-with-nul>".to_owned()
397    })
398}
399
400// Helper type to manage ownership of the strings within a C-style array.
401pub struct CStringArray {
402    items: Vec<CString>,
403    ptrs: Vec<*const c_char>,
404}
405
406impl CStringArray {
407    pub fn with_capacity(capacity: usize) -> Self {
408        let mut result = CStringArray {
409            items: Vec::with_capacity(capacity),
410            ptrs: Vec::with_capacity(capacity + 1),
411        };
412        result.ptrs.push(ptr::null());
413        result
414    }
415    pub fn push(&mut self, item: CString) {
416        let l = self.ptrs.len();
417        self.ptrs[l - 1] = item.as_ptr();
418        self.ptrs.push(ptr::null());
419        self.items.push(item);
420    }
421    pub fn as_ptr(&self) -> *const *const c_char {
422        self.ptrs.as_ptr()
423    }
424}
425
426fn construct_envp(env: BTreeMap<OsString, OsString>, saw_nul: &mut bool) -> CStringArray {
427    let mut result = CStringArray::with_capacity(env.len());
428    for (mut k, v) in env {
429        // Reserve additional space for '=' and null terminator
430        k.reserve_exact(v.len() + 2);
431        k.push("=");
432        k.push(&v);
433
434        // Add the new entry into the array
435        if let Ok(item) = CString::new(k.into_vec()) {
436            result.push(item);
437        } else {
438            *saw_nul = true;
439        }
440    }
441
442    result
443}
444
445impl Stdio {
446    pub fn to_child_stdio(&self, readable: bool) -> io::Result<(ChildStdio, Option<AnonPipe>)> {
447        match *self {
448            Stdio::Inherit => Ok((ChildStdio::Inherit, None)),
449
450            // Make sure that the source descriptors are not an stdio
451            // descriptor, otherwise the order which we set the child's
452            // descriptors may blow away a descriptor which we are hoping to
453            // save. For example, suppose we want the child's stderr to be the
454            // parent's stdout, and the child's stdout to be the parent's
455            // stderr. No matter which we dup first, the second will get
456            // overwritten prematurely.
457            Stdio::Fd(ref fd) => {
458                if fd.as_raw_fd() >= 0 && fd.as_raw_fd() <= libc::STDERR_FILENO {
459                    Ok((ChildStdio::Owned(fd.duplicate()?), None))
460                } else {
461                    Ok((ChildStdio::Explicit(fd.as_raw_fd()), None))
462                }
463            }
464
465            Stdio::StaticFd(fd) => {
466                let fd = FileDesc::from_inner(fd.try_clone_to_owned()?);
467                Ok((ChildStdio::Owned(fd), None))
468            }
469
470            Stdio::MakePipe => {
471                let (reader, writer) = pipe::anon_pipe()?;
472                let (ours, theirs) = if readable { (writer, reader) } else { (reader, writer) };
473                Ok((ChildStdio::Owned(theirs.into_inner()), Some(ours)))
474            }
475
476            #[cfg(not(target_os = "fuchsia"))]
477            Stdio::Null => {
478                let mut opts = OpenOptions::new();
479                opts.read(readable);
480                opts.write(!readable);
481                let fd = File::open_c(DEV_NULL, &opts)?;
482                Ok((ChildStdio::Owned(fd.into_inner()), None))
483            }
484
485            #[cfg(target_os = "fuchsia")]
486            Stdio::Null => Ok((ChildStdio::Null, None)),
487        }
488    }
489}
490
491impl From<AnonPipe> for Stdio {
492    fn from(pipe: AnonPipe) -> Stdio {
493        Stdio::Fd(pipe.into_inner())
494    }
495}
496
497impl From<File> for Stdio {
498    fn from(file: File) -> Stdio {
499        Stdio::Fd(file.into_inner())
500    }
501}
502
503impl From<io::Stdout> for Stdio {
504    fn from(_: io::Stdout) -> Stdio {
505        // This ought really to be is Stdio::StaticFd(input_argument.as_fd()).
506        // But AsFd::as_fd takes its argument by reference, and yields
507        // a bounded lifetime, so it's no use here. There is no AsStaticFd.
508        //
509        // Additionally AsFd is only implemented for the *locked* versions.
510        // We don't want to lock them here.  (The implications of not locking
511        // are the same as those for process::Stdio::inherit().)
512        //
513        // Arguably the hypothetical AsStaticFd and AsFd<'static>
514        // should be implemented for io::Stdout, not just for StdoutLocked.
515        Stdio::StaticFd(unsafe { BorrowedFd::borrow_raw(libc::STDOUT_FILENO) })
516    }
517}
518
519impl From<io::Stderr> for Stdio {
520    fn from(_: io::Stderr) -> Stdio {
521        Stdio::StaticFd(unsafe { BorrowedFd::borrow_raw(libc::STDERR_FILENO) })
522    }
523}
524
525impl ChildStdio {
526    pub fn fd(&self) -> Option<c_int> {
527        match *self {
528            ChildStdio::Inherit => None,
529            ChildStdio::Explicit(fd) => Some(fd),
530            ChildStdio::Owned(ref fd) => Some(fd.as_raw_fd()),
531
532            #[cfg(target_os = "fuchsia")]
533            ChildStdio::Null => None,
534        }
535    }
536}
537
538impl fmt::Debug for Command {
539    // show all attributes but `self.closures` which does not implement `Debug`
540    // and `self.argv` which is not useful for debugging
541    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
542        if f.alternate() {
543            let mut debug_command = f.debug_struct("Command");
544            debug_command.field("program", &self.program).field("args", &self.args);
545            if !self.env.is_unchanged() {
546                debug_command.field("env", &self.env);
547            }
548
549            if self.cwd.is_some() {
550                debug_command.field("cwd", &self.cwd);
551            }
552            if self.uid.is_some() {
553                debug_command.field("uid", &self.uid);
554            }
555            if self.gid.is_some() {
556                debug_command.field("gid", &self.gid);
557            }
558
559            if self.groups.is_some() {
560                debug_command.field("groups", &self.groups);
561            }
562
563            if self.stdin.is_some() {
564                debug_command.field("stdin", &self.stdin);
565            }
566            if self.stdout.is_some() {
567                debug_command.field("stdout", &self.stdout);
568            }
569            if self.stderr.is_some() {
570                debug_command.field("stderr", &self.stderr);
571            }
572            if self.pgroup.is_some() {
573                debug_command.field("pgroup", &self.pgroup);
574            }
575
576            #[cfg(target_os = "linux")]
577            {
578                debug_command.field("create_pidfd", &self.create_pidfd);
579            }
580
581            debug_command.finish()
582        } else {
583            if let Some(ref cwd) = self.cwd {
584                write!(f, "cd {cwd:?} && ")?;
585            }
586            if self.env.does_clear() {
587                write!(f, "env -i ")?;
588                // Altered env vars will be printed next, that should exactly work as expected.
589            } else {
590                // Removed env vars need the command to be wrapped in `env`.
591                let mut any_removed = false;
592                for (key, value_opt) in self.get_envs() {
593                    if value_opt.is_none() {
594                        if !any_removed {
595                            write!(f, "env ")?;
596                            any_removed = true;
597                        }
598                        write!(f, "-u {} ", key.to_string_lossy())?;
599                    }
600                }
601            }
602            // Altered env vars can just be added in front of the program.
603            for (key, value_opt) in self.get_envs() {
604                if let Some(value) = value_opt {
605                    write!(f, "{}={value:?} ", key.to_string_lossy())?;
606                }
607            }
608            if self.program != self.args[0] {
609                write!(f, "[{:?}] ", self.program)?;
610            }
611            write!(f, "{:?}", self.args[0])?;
612
613            for arg in &self.args[1..] {
614                write!(f, " {:?}", arg)?;
615            }
616            Ok(())
617        }
618    }
619}
620
621#[derive(PartialEq, Eq, Clone, Copy)]
622pub struct ExitCode(u8);
623
624impl fmt::Debug for ExitCode {
625    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
626        f.debug_tuple("unix_exit_status").field(&self.0).finish()
627    }
628}
629
630impl ExitCode {
631    pub const SUCCESS: ExitCode = ExitCode(EXIT_SUCCESS as _);
632    pub const FAILURE: ExitCode = ExitCode(EXIT_FAILURE as _);
633
634    #[inline]
635    pub fn as_i32(&self) -> i32 {
636        self.0 as i32
637    }
638}
639
640impl From<u8> for ExitCode {
641    fn from(code: u8) -> Self {
642        Self(code)
643    }
644}
645
646pub struct CommandArgs<'a> {
647    iter: crate::slice::Iter<'a, CString>,
648}
649
650impl<'a> Iterator for CommandArgs<'a> {
651    type Item = &'a OsStr;
652    fn next(&mut self) -> Option<&'a OsStr> {
653        self.iter.next().map(|cs| OsStr::from_bytes(cs.as_bytes()))
654    }
655    fn size_hint(&self) -> (usize, Option<usize>) {
656        self.iter.size_hint()
657    }
658}
659
660impl<'a> ExactSizeIterator for CommandArgs<'a> {
661    fn len(&self) -> usize {
662        self.iter.len()
663    }
664    fn is_empty(&self) -> bool {
665        self.iter.is_empty()
666    }
667}
668
669impl<'a> fmt::Debug for CommandArgs<'a> {
670    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
671        f.debug_list().entries(self.iter.clone()).finish()
672    }
673}
std/sys/pal/unix/process/process_common.rs

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