src/libstd/sys/unix/process/process_common.rs

   1 use crate::os::unix::prelude::*;
   2
   3 use crate::collections::BTreeMap;
   4 use crate::ffi::{CStr, CString, OsStr, OsString};
   5 use crate::fmt;
   6 use crate::io;
   7 use crate::ptr;
   8 use crate::sys::fd::FileDesc;
   9 use crate::sys::fs::File;
  10 use crate::sys::pipe::{self, AnonPipe};
  11 use crate::sys_common::process::CommandEnv;
  12
  13 #[cfg(not(target_os = "fuchsia"))]
  14 use crate::sys::fs::OpenOptions;
  15
  16 use libc::{c_char, c_int, gid_t, uid_t, EXIT_FAILURE, EXIT_SUCCESS};
  17
  18 cfg_if::cfg_if! {
  19     if #[cfg(target_os = "fuchsia")] {
  20         // fuchsia doesn't have /dev/null
  21     } else if #[cfg(target_os = "redox")] {
  22         const DEV_NULL: &str = "null:\0";
  23     } else {
  24         const DEV_NULL: &str = "/dev/null\0";
  25     }
  26 }
  27
  28 // Android with api less than 21 define sig* functions inline, so it is not
  29 // available for dynamic link. Implementing sigemptyset and sigaddset allow us
  30 // to support older Android version (independent of libc version).
  31 // The following implementations are based on https://git.io/vSkNf
  32 cfg_if::cfg_if! {
  33     if #[cfg(target_os = "android")] {
  34         pub unsafe fn sigemptyset(set: *mut libc::sigset_t) -> libc::c_int {
  35             set.write_bytes(0u8, 1);
  36             return 0;
  37         }
  38         #[allow(dead_code)]
  39         pub unsafe fn sigaddset(set: *mut libc::sigset_t, signum: libc::c_int) -> libc::c_int {
  40             use crate::{slice, mem};
  41
  42             let raw = slice::from_raw_parts_mut(set as *mut u8, mem::size_of::<libc::sigset_t>());
  43             let bit = (signum - 1) as usize;
  44             raw[bit / 8] |= 1 << (bit % 8);
  45             return 0;
  46         }
  47     } else {
  48         pub use libc::{sigemptyset, sigaddset};
  49     }
  50 }
  51
  52 ////////////////////////////////////////////////////////////////////////////////
  53 // Command
  54 ////////////////////////////////////////////////////////////////////////////////
  55
  56 pub struct Command {
  57     // Currently we try hard to ensure that the call to `.exec()` doesn't
  58     // actually allocate any memory. While many platforms try to ensure that
  59     // memory allocation works after a fork in a multithreaded process, it's
  60     // been observed to be buggy and somewhat unreliable, so we do our best to
  61     // just not do it at all!
  62     //
  63     // Along those lines, the `argv` and `envp` raw pointers here are exactly
  64     // what's gonna get passed to `execvp`. The `argv` array starts with the
  65     // `program` and ends with a NULL, and the `envp` pointer, if present, is
  66     // also null-terminated.
  67     //
  68     // Right now we don't support removing arguments, so there's no much fancy
  69     // support there, but we support adding and removing environment variables,
  70     // so a side table is used to track where in the `envp` array each key is
  71     // located. Whenever we add a key we update it in place if it's already
  72     // present, and whenever we remove a key we update the locations of all
  73     // other keys.
  74     program: CString,
  75     args: Vec<CString>,
  76     argv: Argv,
  77     env: CommandEnv,
  78
  79     cwd: Option<CString>,
  80     uid: Option<uid_t>,
  81     gid: Option<gid_t>,
  82     saw_nul: bool,
  83     closures: Vec<Box<dyn FnMut() -> io::Result<()> + Send + Sync>>,
  84     stdin: Option<Stdio>,
  85     stdout: Option<Stdio>,
  86     stderr: Option<Stdio>,
  87 }
  88
  89 // Create a new type for argv, so that we can make it `Send` and `Sync`
  90 struct Argv(Vec<*const c_char>);
  91
  92 // It is safe to make `Argv` `Send` and `Sync`, because it contains
  93 // pointers to memory owned by `Command.args`
  94 unsafe impl Send for Argv {}
  95 unsafe impl Sync for Argv {}
  96
  97 // passed back to std::process with the pipes connected to the child, if any
  98 // were requested
  99 pub struct StdioPipes {
 100     pub stdin: Option<AnonPipe>,
 101     pub stdout: Option<AnonPipe>,
 102     pub stderr: Option<AnonPipe>,
 103 }
 104
 105 // passed to do_exec() with configuration of what the child stdio should look
 106 // like
 107 pub struct ChildPipes {
 108     pub stdin: ChildStdio,
 109     pub stdout: ChildStdio,
 110     pub stderr: ChildStdio,
 111 }
 112
 113 pub enum ChildStdio {
 114     Inherit,
 115     Explicit(c_int),
 116     Owned(FileDesc),
 117
 118     // On Fuchsia, null stdio is the default, so we simply don't specify
 119     // any actions at the time of spawning.
 120     #[cfg(target_os = "fuchsia")]
 121     Null,
 122 }
 123
 124 pub enum Stdio {
 125     Inherit,
 126     Null,
 127     MakePipe,
 128     Fd(FileDesc),
 129 }
 130
 131 impl Command {
 132     pub fn new(program: &OsStr) -> Command {
 133         let mut saw_nul = false;
 134         let program = os2c(program, &mut saw_nul);
 135         Command {
 136             argv: Argv(vec![program.as_ptr(), ptr::null()]),
 137             args: vec![program.clone()],
 138             program,
 139             env: Default::default(),
 140             cwd: None,
 141             uid: None,
 142             gid: None,
 143             saw_nul,
 144             closures: Vec::new(),
 145             stdin: None,
 146             stdout: None,
 147             stderr: None,
 148         }
 149     }
 150
 151     pub fn set_arg_0(&mut self, arg: &OsStr) {
 152         // Set a new arg0
 153         let arg = os2c(arg, &mut self.saw_nul);
 154         debug_assert!(self.argv.0.len() > 1);
 155         self.argv.0[0] = arg.as_ptr();
 156         self.args[0] = arg;
 157     }
 158
 159     pub fn arg(&mut self, arg: &OsStr) {
 160         // Overwrite the trailing NULL pointer in `argv` and then add a new null
 161         // pointer.
 162         let arg = os2c(arg, &mut self.saw_nul);
 163         self.argv.0[self.args.len()] = arg.as_ptr();
 164         self.argv.0.push(ptr::null());
 165
 166         // Also make sure we keep track of the owned value to schedule a
 167         // destructor for this memory.
 168         self.args.push(arg);
 169     }
 170
 171     pub fn cwd(&mut self, dir: &OsStr) {
 172         self.cwd = Some(os2c(dir, &mut self.saw_nul));
 173     }
 174     pub fn uid(&mut self, id: uid_t) {
 175         self.uid = Some(id);
 176     }
 177     pub fn gid(&mut self, id: gid_t) {
 178         self.gid = Some(id);
 179     }
 180
 181     pub fn saw_nul(&self) -> bool {
 182         self.saw_nul
 183     }
 184     pub fn get_argv(&self) -> &Vec<*const c_char> {
 185         &self.argv.0
 186     }
 187
 188     pub fn get_program(&self) -> &CStr {
 189         &*self.program
 190     }
 191
 192     #[allow(dead_code)]
 193     pub fn get_cwd(&self) -> &Option<CString> {
 194         &self.cwd
 195     }
 196     #[allow(dead_code)]
 197     pub fn get_uid(&self) -> Option<uid_t> {
 198         self.uid
 199     }
 200     #[allow(dead_code)]
 201     pub fn get_gid(&self) -> Option<gid_t> {
 202         self.gid
 203     }
 204
 205     pub fn get_closures(&mut self) -> &mut Vec<Box<dyn FnMut() -> io::Result<()> + Send + Sync>> {
 206         &mut self.closures
 207     }
 208
 209     pub unsafe fn pre_exec(&mut self, f: Box<dyn FnMut() -> io::Result<()> + Send + Sync>) {
 210         self.closures.push(f);
 211     }
 212
 213     pub fn stdin(&mut self, stdin: Stdio) {
 214         self.stdin = Some(stdin);
 215     }
 216
 217     pub fn stdout(&mut self, stdout: Stdio) {
 218         self.stdout = Some(stdout);
 219     }
 220
 221     pub fn stderr(&mut self, stderr: Stdio) {
 222         self.stderr = Some(stderr);
 223     }
 224
 225     pub fn env_mut(&mut self) -> &mut CommandEnv {
 226         &mut self.env
 227     }
 228
 229     pub fn capture_env(&mut self) -> Option<CStringArray> {
 230         let maybe_env = self.env.capture_if_changed();
 231         maybe_env.map(|env| construct_envp(env, &mut self.saw_nul))
 232     }
 233     #[allow(dead_code)]
 234     pub fn env_saw_path(&self) -> bool {
 235         self.env.have_changed_path()
 236     }
 237
 238     pub fn setup_io(
 239         &self,
 240         default: Stdio,
 241         needs_stdin: bool,
 242     ) -> io::Result<(StdioPipes, ChildPipes)> {
 243         let null = Stdio::Null;
 244         let default_stdin = if needs_stdin { &default } else { &null };
 245         let stdin = self.stdin.as_ref().unwrap_or(default_stdin);
 246         let stdout = self.stdout.as_ref().unwrap_or(&default);
 247         let stderr = self.stderr.as_ref().unwrap_or(&default);
 248         let (their_stdin, our_stdin) = stdin.to_child_stdio(true)?;
 249         let (their_stdout, our_stdout) = stdout.to_child_stdio(false)?;
 250         let (their_stderr, our_stderr) = stderr.to_child_stdio(false)?;
 251         let ours = StdioPipes { stdin: our_stdin, stdout: our_stdout, stderr: our_stderr };
 252         let theirs = ChildPipes { stdin: their_stdin, stdout: their_stdout, stderr: their_stderr };
 253         Ok((ours, theirs))
 254     }
 255 }
 256
 257 fn os2c(s: &OsStr, saw_nul: &mut bool) -> CString {
 258     CString::new(s.as_bytes()).unwrap_or_else(|_e| {
 259         *saw_nul = true;
 260         CString::new("<string-with-nul>").unwrap()
 261     })
 262 }
 263
 264 // Helper type to manage ownership of the strings within a C-style array.
 265 pub struct CStringArray {
 266     items: Vec<CString>,
 267     ptrs: Vec<*const c_char>,
 268 }
 269
 270 impl CStringArray {
 271     pub fn with_capacity(capacity: usize) -> Self {
 272         let mut result = CStringArray {
 273             items: Vec::with_capacity(capacity),
 274             ptrs: Vec::with_capacity(capacity + 1),
 275         };
 276         result.ptrs.push(ptr::null());
 277         result
 278     }
 279     pub fn push(&mut self, item: CString) {
 280         let l = self.ptrs.len();
 281         self.ptrs[l - 1] = item.as_ptr();
 282         self.ptrs.push(ptr::null());
 283         self.items.push(item);
 284     }
 285     pub fn as_ptr(&self) -> *const *const c_char {
 286         self.ptrs.as_ptr()
 287     }
 288 }
 289
 290 fn construct_envp(env: BTreeMap<OsString, OsString>, saw_nul: &mut bool) -> CStringArray {
 291     let mut result = CStringArray::with_capacity(env.len());
 292     for (mut k, v) in env {
 293         // Reserve additional space for '=' and null terminator
 294         k.reserve_exact(v.len() + 2);
 295         k.push("=");
 296         k.push(&v);
 297
 298         // Add the new entry into the array
 299         if let Ok(item) = CString::new(k.into_vec()) {
 300             result.push(item);
 301         } else {
 302             *saw_nul = true;
 303         }
 304     }
 305
 306     result
 307 }
 308
 309 impl Stdio {
 310     pub fn to_child_stdio(&self, readable: bool) -> io::Result<(ChildStdio, Option<AnonPipe>)> {
 311         match *self {
 312             Stdio::Inherit => Ok((ChildStdio::Inherit, None)),
 313
 314             // Make sure that the source descriptors are not an stdio
 315             // descriptor, otherwise the order which we set the child's
 316             // descriptors may blow away a descriptor which we are hoping to
 317             // save. For example, suppose we want the child's stderr to be the
 318             // parent's stdout, and the child's stdout to be the parent's
 319             // stderr. No matter which we dup first, the second will get
 320             // overwritten prematurely.
 321             Stdio::Fd(ref fd) => {
 322                 if fd.raw() >= 0 && fd.raw() <= libc::STDERR_FILENO {
 323                     Ok((ChildStdio::Owned(fd.duplicate()?), None))
 324                 } else {
 325                     Ok((ChildStdio::Explicit(fd.raw()), None))
 326                 }
 327             }
 328
 329             Stdio::MakePipe => {
 330                 let (reader, writer) = pipe::anon_pipe()?;
 331                 let (ours, theirs) = if readable { (writer, reader) } else { (reader, writer) };
 332                 Ok((ChildStdio::Owned(theirs.into_fd()), Some(ours)))
 333             }
 334
 335             #[cfg(not(target_os = "fuchsia"))]
 336             Stdio::Null => {
 337                 let mut opts = OpenOptions::new();
 338                 opts.read(readable);
 339                 opts.write(!readable);
 340                 let path = unsafe { CStr::from_ptr(DEV_NULL.as_ptr() as *const _) };
 341                 let fd = File::open_c(&path, &opts)?;
 342                 Ok((ChildStdio::Owned(fd.into_fd()), None))
 343             }
 344
 345             #[cfg(target_os = "fuchsia")]
 346             Stdio::Null => Ok((ChildStdio::Null, None)),
 347         }
 348     }
 349 }
 350
 351 impl From<AnonPipe> for Stdio {
 352     fn from(pipe: AnonPipe) -> Stdio {
 353         Stdio::Fd(pipe.into_fd())
 354     }
 355 }
 356
 357 impl From<File> for Stdio {
 358     fn from(file: File) -> Stdio {
 359         Stdio::Fd(file.into_fd())
 360     }
 361 }
 362
 363 impl ChildStdio {
 364     pub fn fd(&self) -> Option<c_int> {
 365         match *self {
 366             ChildStdio::Inherit => None,
 367             ChildStdio::Explicit(fd) => Some(fd),
 368             ChildStdio::Owned(ref fd) => Some(fd.raw()),
 369
 370             #[cfg(target_os = "fuchsia")]
 371             ChildStdio::Null => None,
 372         }
 373     }
 374 }
 375
 376 impl fmt::Debug for Command {
 377     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 378         if self.program != self.args[0] {
 379             write!(f, "[{:?}] ", self.program)?;
 380         }
 381         write!(f, "{:?}", self.args[0])?;
 382
 383         for arg in &self.args[1..] {
 384             write!(f, " {:?}", arg)?;
 385         }
 386         Ok(())
 387     }
 388 }
 389
 390 #[derive(PartialEq, Eq, Clone, Copy, Debug)]
 391 pub struct ExitCode(u8);
 392
 393 impl ExitCode {
 394     pub const SUCCESS: ExitCode = ExitCode(EXIT_SUCCESS as _);
 395     pub const FAILURE: ExitCode = ExitCode(EXIT_FAILURE as _);
 396
 397     #[inline]
 398     pub fn as_i32(&self) -> i32 {
 399         self.0 as i32
 400     }
 401 }
 402
 403 #[cfg(all(test, not(target_os = "emscripten")))]
 404 mod tests {
 405     use super::*;
 406
 407     use crate::ffi::OsStr;
 408     use crate::mem;
 409     use crate::ptr;
 410     use crate::sys::cvt;
 411
 412     macro_rules! t {
 413         ($e:expr) => {
 414             match $e {
 415                 Ok(t) => t,
 416                 Err(e) => panic!("received error for `{}`: {}", stringify!($e), e),
 417             }
 418         };
 419     }
 420
 421     // See #14232 for more information, but it appears that signal delivery to a
 422     // newly spawned process may just be raced in the macOS, so to prevent this
 423     // test from being flaky we ignore it on macOS.
 424     #[test]
 425     #[cfg_attr(target_os = "macos", ignore)]
 426     // When run under our current QEMU emulation test suite this test fails,
 427     // although the reason isn't very clear as to why. For now this test is
 428     // ignored there.
 429     #[cfg_attr(target_arch = "arm", ignore)]
 430     #[cfg_attr(target_arch = "aarch64", ignore)]
 431     #[cfg_attr(target_arch = "riscv64", ignore)]
 432     fn test_process_mask() {
 433         unsafe {
 434             // Test to make sure that a signal mask does not get inherited.
 435             let mut cmd = Command::new(OsStr::new("cat"));
 436
 437             let mut set = mem::MaybeUninit::<libc::sigset_t>::uninit();
 438             let mut old_set = mem::MaybeUninit::<libc::sigset_t>::uninit();
 439             t!(cvt(sigemptyset(set.as_mut_ptr())));
 440             t!(cvt(sigaddset(set.as_mut_ptr(), libc::SIGINT)));
 441             t!(cvt(libc::pthread_sigmask(libc::SIG_SETMASK, set.as_ptr(), old_set.as_mut_ptr())));
 442
 443             cmd.stdin(Stdio::MakePipe);
 444             cmd.stdout(Stdio::MakePipe);
 445
 446             let (mut cat, mut pipes) = t!(cmd.spawn(Stdio::Null, true));
 447             let stdin_write = pipes.stdin.take().unwrap();
 448             let stdout_read = pipes.stdout.take().unwrap();
 449
 450             t!(cvt(libc::pthread_sigmask(libc::SIG_SETMASK, old_set.as_ptr(), ptr::null_mut())));
 451
 452             t!(cvt(libc::kill(cat.id() as libc::pid_t, libc::SIGINT)));
 453             // We need to wait until SIGINT is definitely delivered. The
 454             // easiest way is to write something to cat, and try to read it
 455             // back: if SIGINT is unmasked, it'll get delivered when cat is
 456             // next scheduled.
 457             let _ = stdin_write.write(b"Hello");
 458             drop(stdin_write);
 459
 460             // Either EOF or failure (EPIPE) is okay.
 461             let mut buf = [0; 5];
 462             if let Ok(ret) = stdout_read.read(&mut buf) {
 463                 assert_eq!(ret, 0);
 464             }
 465
 466             t!(cat.wait());
 467         }
 468     }
 469 }