diff options
Diffstat (limited to 'library/std/src/sys/unix/process/process_common.rs')
| -rw-r--r-- | library/std/src/sys/unix/process/process_common.rs | 469 |
1 files changed, 469 insertions, 0 deletions
diff --git a/library/std/src/sys/unix/process/process_common.rs b/library/std/src/sys/unix/process/process_common.rs new file mode 100644 index 00000000000..6e33cdd3c48 --- /dev/null +++ b/library/std/src/sys/unix/process/process_common.rs @@ -0,0 +1,469 @@ +use crate::os::unix::prelude::*; + +use crate::collections::BTreeMap; +use crate::ffi::{CStr, CString, OsStr, OsString}; +use crate::fmt; +use crate::io; +use crate::ptr; +use crate::sys::fd::FileDesc; +use crate::sys::fs::File; +use crate::sys::pipe::{self, AnonPipe}; +use crate::sys_common::process::CommandEnv; + +#[cfg(not(target_os = "fuchsia"))] +use crate::sys::fs::OpenOptions; + +use libc::{c_char, c_int, gid_t, uid_t, EXIT_FAILURE, EXIT_SUCCESS}; + +cfg_if::cfg_if! { + if #[cfg(target_os = "fuchsia")] { + // fuchsia doesn't have /dev/null + } else if #[cfg(target_os = "redox")] { + const DEV_NULL: &str = "null:\0"; + } else { + const DEV_NULL: &str = "/dev/null\0"; + } +} + +// Android with api less than 21 define sig* functions inline, so it is not +// available for dynamic link. Implementing sigemptyset and sigaddset allow us +// to support older Android version (independent of libc version). +// The following implementations are based on https://git.io/vSkNf +cfg_if::cfg_if! { + if #[cfg(target_os = "android")] { + pub unsafe fn sigemptyset(set: *mut libc::sigset_t) -> libc::c_int { + set.write_bytes(0u8, 1); + return 0; + } + #[allow(dead_code)] + pub unsafe fn sigaddset(set: *mut libc::sigset_t, signum: libc::c_int) -> libc::c_int { + use crate::{slice, mem}; + + let raw = slice::from_raw_parts_mut(set as *mut u8, mem::size_of::<libc::sigset_t>()); + let bit = (signum - 1) as usize; + raw[bit / 8] |= 1 << (bit % 8); + return 0; + } + } else { + pub use libc::{sigemptyset, sigaddset}; + } +} + +//////////////////////////////////////////////////////////////////////////////// +// Command +//////////////////////////////////////////////////////////////////////////////// + +pub struct Command { + // Currently we try hard to ensure that the call to `.exec()` doesn't + // actually allocate any memory. While many platforms try to ensure that + // memory allocation works after a fork in a multithreaded process, it's + // been observed to be buggy and somewhat unreliable, so we do our best to + // just not do it at all! + // + // Along those lines, the `argv` and `envp` raw pointers here are exactly + // what's gonna get passed to `execvp`. The `argv` array starts with the + // `program` and ends with a NULL, and the `envp` pointer, if present, is + // also null-terminated. + // + // Right now we don't support removing arguments, so there's no much fancy + // support there, but we support adding and removing environment variables, + // so a side table is used to track where in the `envp` array each key is + // located. Whenever we add a key we update it in place if it's already + // present, and whenever we remove a key we update the locations of all + // other keys. + program: CString, + args: Vec<CString>, + argv: Argv, + env: CommandEnv, + + cwd: Option<CString>, + uid: Option<uid_t>, + gid: Option<gid_t>, + saw_nul: bool, + closures: Vec<Box<dyn FnMut() -> io::Result<()> + Send + Sync>>, + stdin: Option<Stdio>, + stdout: Option<Stdio>, + stderr: Option<Stdio>, +} + +// Create a new type for argv, so that we can make it `Send` and `Sync` +struct Argv(Vec<*const c_char>); + +// It is safe to make `Argv` `Send` and `Sync`, because it contains +// pointers to memory owned by `Command.args` +unsafe impl Send for Argv {} +unsafe impl Sync for Argv {} + +// passed back to std::process with the pipes connected to the child, if any +// were requested +pub struct StdioPipes { + pub stdin: Option<AnonPipe>, + pub stdout: Option<AnonPipe>, + pub stderr: Option<AnonPipe>, +} + +// passed to do_exec() with configuration of what the child stdio should look +// like +pub struct ChildPipes { + pub stdin: ChildStdio, + pub stdout: ChildStdio, + pub stderr: ChildStdio, +} + +pub enum ChildStdio { + Inherit, + Explicit(c_int), + Owned(FileDesc), + + // On Fuchsia, null stdio is the default, so we simply don't specify + // any actions at the time of spawning. + #[cfg(target_os = "fuchsia")] + Null, +} + +pub enum Stdio { + Inherit, + Null, + MakePipe, + Fd(FileDesc), +} + +impl Command { + pub fn new(program: &OsStr) -> Command { + let mut saw_nul = false; + let program = os2c(program, &mut saw_nul); + Command { + argv: Argv(vec![program.as_ptr(), ptr::null()]), + args: vec![program.clone()], + program, + env: Default::default(), + cwd: None, + uid: None, + gid: None, + saw_nul, + closures: Vec::new(), + stdin: None, + stdout: None, + stderr: None, + } + } + + pub fn set_arg_0(&mut self, arg: &OsStr) { + // Set a new arg0 + let arg = os2c(arg, &mut self.saw_nul); + debug_assert!(self.argv.0.len() > 1); + self.argv.0[0] = arg.as_ptr(); + self.args[0] = arg; + } + + pub fn arg(&mut self, arg: &OsStr) { + // Overwrite the trailing NULL pointer in `argv` and then add a new null + // pointer. + let arg = os2c(arg, &mut self.saw_nul); + self.argv.0[self.args.len()] = arg.as_ptr(); + self.argv.0.push(ptr::null()); + + // Also make sure we keep track of the owned value to schedule a + // destructor for this memory. + self.args.push(arg); + } + + pub fn cwd(&mut self, dir: &OsStr) { + self.cwd = Some(os2c(dir, &mut self.saw_nul)); + } + pub fn uid(&mut self, id: uid_t) { + self.uid = Some(id); + } + pub fn gid(&mut self, id: gid_t) { + self.gid = Some(id); + } + + pub fn saw_nul(&self) -> bool { + self.saw_nul + } + pub fn get_argv(&self) -> &Vec<*const c_char> { + &self.argv.0 + } + + pub fn get_program(&self) -> &CStr { + &*self.program + } + + #[allow(dead_code)] + pub fn get_cwd(&self) -> &Option<CString> { + &self.cwd + } + #[allow(dead_code)] + pub fn get_uid(&self) -> Option<uid_t> { + self.uid + } + #[allow(dead_code)] + pub fn get_gid(&self) -> Option<gid_t> { + self.gid + } + + pub fn get_closures(&mut self) -> &mut Vec<Box<dyn FnMut() -> io::Result<()> + Send + Sync>> { + &mut self.closures + } + + pub unsafe fn pre_exec(&mut self, f: Box<dyn FnMut() -> io::Result<()> + Send + Sync>) { + self.closures.push(f); + } + + pub fn stdin(&mut self, stdin: Stdio) { + self.stdin = Some(stdin); + } + + pub fn stdout(&mut self, stdout: Stdio) { + self.stdout = Some(stdout); + } + + pub fn stderr(&mut self, stderr: Stdio) { + self.stderr = Some(stderr); + } + + pub fn env_mut(&mut self) -> &mut CommandEnv { + &mut self.env + } + + pub fn capture_env(&mut self) -> Option<CStringArray> { + let maybe_env = self.env.capture_if_changed(); + maybe_env.map(|env| construct_envp(env, &mut self.saw_nul)) + } + #[allow(dead_code)] + pub fn env_saw_path(&self) -> bool { + self.env.have_changed_path() + } + + pub fn setup_io( + &self, + default: Stdio, + needs_stdin: bool, + ) -> io::Result<(StdioPipes, ChildPipes)> { + let null = Stdio::Null; + let default_stdin = if needs_stdin { &default } else { &null }; + let stdin = self.stdin.as_ref().unwrap_or(default_stdin); + let stdout = self.stdout.as_ref().unwrap_or(&default); + let stderr = self.stderr.as_ref().unwrap_or(&default); + let (their_stdin, our_stdin) = stdin.to_child_stdio(true)?; + let (their_stdout, our_stdout) = stdout.to_child_stdio(false)?; + let (their_stderr, our_stderr) = stderr.to_child_stdio(false)?; + let ours = StdioPipes { stdin: our_stdin, stdout: our_stdout, stderr: our_stderr }; + let theirs = ChildPipes { stdin: their_stdin, stdout: their_stdout, stderr: their_stderr }; + Ok((ours, theirs)) + } +} + +fn os2c(s: &OsStr, saw_nul: &mut bool) -> CString { + CString::new(s.as_bytes()).unwrap_or_else(|_e| { + *saw_nul = true; + CString::new("<string-with-nul>").unwrap() + }) +} + +// Helper type to manage ownership of the strings within a C-style array. +pub struct CStringArray { + items: Vec<CString>, + ptrs: Vec<*const c_char>, +} + +impl CStringArray { + pub fn with_capacity(capacity: usize) -> Self { + let mut result = CStringArray { + items: Vec::with_capacity(capacity), + ptrs: Vec::with_capacity(capacity + 1), + }; + result.ptrs.push(ptr::null()); + result + } + pub fn push(&mut self, item: CString) { + let l = self.ptrs.len(); + self.ptrs[l - 1] = item.as_ptr(); + self.ptrs.push(ptr::null()); + self.items.push(item); + } + pub fn as_ptr(&self) -> *const *const c_char { + self.ptrs.as_ptr() + } +} + +fn construct_envp(env: BTreeMap<OsString, OsString>, saw_nul: &mut bool) -> CStringArray { + let mut result = CStringArray::with_capacity(env.len()); + for (mut k, v) in env { + // Reserve additional space for '=' and null terminator + k.reserve_exact(v.len() + 2); + k.push("="); + k.push(&v); + + // Add the new entry into the array + if let Ok(item) = CString::new(k.into_vec()) { + result.push(item); + } else { + *saw_nul = true; + } + } + + result +} + +impl Stdio { + pub fn to_child_stdio(&self, readable: bool) -> io::Result<(ChildStdio, Option<AnonPipe>)> { + match *self { + Stdio::Inherit => Ok((ChildStdio::Inherit, None)), + + // Make sure that the source descriptors are not an stdio + // descriptor, otherwise the order which we set the child's + // descriptors may blow away a descriptor which we are hoping to + // save. For example, suppose we want the child's stderr to be the + // parent's stdout, and the child's stdout to be the parent's + // stderr. No matter which we dup first, the second will get + // overwritten prematurely. + Stdio::Fd(ref fd) => { + if fd.raw() >= 0 && fd.raw() <= libc::STDERR_FILENO { + Ok((ChildStdio::Owned(fd.duplicate()?), None)) + } else { + Ok((ChildStdio::Explicit(fd.raw()), None)) + } + } + + Stdio::MakePipe => { + let (reader, writer) = pipe::anon_pipe()?; + let (ours, theirs) = if readable { (writer, reader) } else { (reader, writer) }; + Ok((ChildStdio::Owned(theirs.into_fd()), Some(ours))) + } + + #[cfg(not(target_os = "fuchsia"))] + Stdio::Null => { + let mut opts = OpenOptions::new(); + opts.read(readable); + opts.write(!readable); + let path = unsafe { CStr::from_ptr(DEV_NULL.as_ptr() as *const _) }; + let fd = File::open_c(&path, &opts)?; + Ok((ChildStdio::Owned(fd.into_fd()), None)) + } + + #[cfg(target_os = "fuchsia")] + Stdio::Null => Ok((ChildStdio::Null, None)), + } + } +} + +impl From<AnonPipe> for Stdio { + fn from(pipe: AnonPipe) -> Stdio { + Stdio::Fd(pipe.into_fd()) + } +} + +impl From<File> for Stdio { + fn from(file: File) -> Stdio { + Stdio::Fd(file.into_fd()) + } +} + +impl ChildStdio { + pub fn fd(&self) -> Option<c_int> { + match *self { + ChildStdio::Inherit => None, + ChildStdio::Explicit(fd) => Some(fd), + ChildStdio::Owned(ref fd) => Some(fd.raw()), + + #[cfg(target_os = "fuchsia")] + ChildStdio::Null => None, + } + } +} + +impl fmt::Debug for Command { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + if self.program != self.args[0] { + write!(f, "[{:?}] ", self.program)?; + } + write!(f, "{:?}", self.args[0])?; + + for arg in &self.args[1..] { + write!(f, " {:?}", arg)?; + } + Ok(()) + } +} + +#[derive(PartialEq, Eq, Clone, Copy, Debug)] +pub struct ExitCode(u8); + +impl ExitCode { + pub const SUCCESS: ExitCode = ExitCode(EXIT_SUCCESS as _); + pub const FAILURE: ExitCode = ExitCode(EXIT_FAILURE as _); + + #[inline] + pub fn as_i32(&self) -> i32 { + self.0 as i32 + } +} + +#[cfg(all(test, not(target_os = "emscripten")))] +mod tests { + use super::*; + + use crate::ffi::OsStr; + use crate::mem; + use crate::ptr; + use crate::sys::cvt; + + macro_rules! t { + ($e:expr) => { + match $e { + Ok(t) => t, + Err(e) => panic!("received error for `{}`: {}", stringify!($e), e), + } + }; + } + + // See #14232 for more information, but it appears that signal delivery to a + // newly spawned process may just be raced in the macOS, so to prevent this + // test from being flaky we ignore it on macOS. + #[test] + #[cfg_attr(target_os = "macos", ignore)] + // When run under our current QEMU emulation test suite this test fails, + // although the reason isn't very clear as to why. For now this test is + // ignored there. + #[cfg_attr(target_arch = "arm", ignore)] + #[cfg_attr(target_arch = "aarch64", ignore)] + #[cfg_attr(target_arch = "riscv64", ignore)] + fn test_process_mask() { + unsafe { + // Test to make sure that a signal mask does not get inherited. + let mut cmd = Command::new(OsStr::new("cat")); + + let mut set = mem::MaybeUninit::<libc::sigset_t>::uninit(); + let mut old_set = mem::MaybeUninit::<libc::sigset_t>::uninit(); + t!(cvt(sigemptyset(set.as_mut_ptr()))); + t!(cvt(sigaddset(set.as_mut_ptr(), libc::SIGINT))); + t!(cvt(libc::pthread_sigmask(libc::SIG_SETMASK, set.as_ptr(), old_set.as_mut_ptr()))); + + cmd.stdin(Stdio::MakePipe); + cmd.stdout(Stdio::MakePipe); + + let (mut cat, mut pipes) = t!(cmd.spawn(Stdio::Null, true)); + let stdin_write = pipes.stdin.take().unwrap(); + let stdout_read = pipes.stdout.take().unwrap(); + + t!(cvt(libc::pthread_sigmask(libc::SIG_SETMASK, old_set.as_ptr(), ptr::null_mut()))); + + t!(cvt(libc::kill(cat.id() as libc::pid_t, libc::SIGINT))); + // We need to wait until SIGINT is definitely delivered. The + // easiest way is to write something to cat, and try to read it + // back: if SIGINT is unmasked, it'll get delivered when cat is + // next scheduled. + let _ = stdin_write.write(b"Hello"); + drop(stdin_write); + + // Either EOF or failure (EPIPE) is okay. + let mut buf = [0; 5]; + if let Ok(ret) = stdout_read.read(&mut buf) { + assert_eq!(ret, 0); + } + + t!(cat.wait()); + } + } +} |