diff options
Diffstat (limited to '')
58 files changed, 1151 insertions, 1025 deletions
diff --git a/library/std/src/sys_common/remutex.rs b/library/std/src/sync/remutex.rs index 4c054da64..4c054da64 100644 --- a/library/std/src/sys_common/remutex.rs +++ b/library/std/src/sync/remutex.rs diff --git a/library/std/src/sys/itron/thread.rs b/library/std/src/sys/itron/thread.rs index c2b366808..19350b83f 100644 --- a/library/std/src/sys/itron/thread.rs +++ b/library/std/src/sys/itron/thread.rs @@ -119,7 +119,7 @@ impl Thread { let old_lifecycle = inner .lifecycle - .swap(LIFECYCLE_EXITED_OR_FINISHED_OR_JOIN_FINALIZE, Ordering::Release); + .swap(LIFECYCLE_EXITED_OR_FINISHED_OR_JOIN_FINALIZE, Ordering::AcqRel); match old_lifecycle { LIFECYCLE_DETACHED => { @@ -129,9 +129,9 @@ impl Thread { // In this case, `*p_inner`'s ownership has been moved to // us, and we are responsible for dropping it. The acquire - // ordering is not necessary because the parent thread made - // no memory access needing synchronization since the call - // to `acre_tsk`. + // ordering ensures that the swap operation that wrote + // `LIFECYCLE_DETACHED` happens-before `Box::from_raw( + // p_inner)`. // Safety: See above. let _ = unsafe { Box::from_raw(p_inner) }; @@ -151,6 +151,9 @@ impl Thread { // Since the parent might drop `*inner` and terminate us as // soon as it sees `JOIN_FINALIZE`, the release ordering // must be used in the above `swap` call. + // + // To make the task referred to by `parent_tid` visible, we + // must use the acquire ordering in the above `swap` call. // [JOINING → JOIN_FINALIZE] // Wake up the parent task. @@ -218,11 +221,15 @@ impl Thread { let current_task = current_task as usize; - match inner.lifecycle.swap(current_task, Ordering::Acquire) { + match inner.lifecycle.swap(current_task, Ordering::AcqRel) { LIFECYCLE_INIT => { // [INIT → JOINING] // The child task will transition the state to `JOIN_FINALIZE` // and wake us up. + // + // To make the task referred to by `current_task` visible from + // the child task's point of view, we must use the release + // ordering in the above `swap` call. loop { expect_success_aborting(unsafe { abi::slp_tsk() }, &"slp_tsk"); // To synchronize with the child task's memory accesses to @@ -267,15 +274,15 @@ impl Drop for Thread { let inner = unsafe { self.p_inner.as_ref() }; // Detach the thread. - match inner.lifecycle.swap(LIFECYCLE_DETACHED_OR_JOINED, Ordering::Acquire) { + match inner.lifecycle.swap(LIFECYCLE_DETACHED_OR_JOINED, Ordering::AcqRel) { LIFECYCLE_INIT => { // [INIT → DETACHED] // When the time comes, the child will figure out that no // one will ever join it. // The ownership of `*p_inner` is moved to the child thread. - // However, the release ordering is not necessary because we - // made no memory access needing synchronization since the call - // to `acre_tsk`. + // The release ordering ensures that the above swap operation on + // `lifecycle` happens-before the child thread's + // `Box::from_raw(p_inner)`. } LIFECYCLE_FINISHED => { // [FINISHED → JOINED] @@ -287,7 +294,7 @@ impl Drop for Thread { // Terminate and delete the task // Safety: `self.task` still represents a task we own (because // this method or `join_inner` is called only once for - // each `Thread`). The task indicated that it's safe to + // each `Thread`). The task indicated that it's safe to // delete by entering the `FINISHED` state. unsafe { terminate_and_delete_task(self.task) }; diff --git a/library/std/src/sys/sgx/mod.rs b/library/std/src/sys/sgx/mod.rs index 01e4ffe3d..9865a945b 100644 --- a/library/std/src/sys/sgx/mod.rs +++ b/library/std/src/sys/sgx/mod.rs @@ -34,6 +34,7 @@ pub mod process; pub mod stdio; pub mod thread; pub mod thread_local_key; +pub mod thread_parking; pub mod time; mod condvar; diff --git a/library/std/src/sys/sgx/thread.rs b/library/std/src/sys/sgx/thread.rs index d745a6196..1608b8cb6 100644 --- a/library/std/src/sys/sgx/thread.rs +++ b/library/std/src/sys/sgx/thread.rs @@ -65,39 +65,36 @@ mod task_queue { /// execution. The signal is sent once all TLS destructors have finished at /// which point no new thread locals should be created. pub mod wait_notify { - use super::super::waitqueue::{SpinMutex, WaitQueue, WaitVariable}; + use crate::pin::Pin; use crate::sync::Arc; + use crate::sys_common::thread_parking::Parker; - pub struct Notifier(Arc<SpinMutex<WaitVariable<bool>>>); + pub struct Notifier(Arc<Parker>); impl Notifier { /// Notify the waiter. The waiter is either notified right away (if /// currently blocked in `Waiter::wait()`) or later when it calls the /// `Waiter::wait()` method. pub fn notify(self) { - let mut guard = self.0.lock(); - *guard.lock_var_mut() = true; - let _ = WaitQueue::notify_one(guard); + Pin::new(&*self.0).unpark() } } - pub struct Waiter(Arc<SpinMutex<WaitVariable<bool>>>); + pub struct Waiter(Arc<Parker>); impl Waiter { /// Wait for a notification. If `Notifier::notify()` has already been /// called, this will return immediately, otherwise the current thread /// is blocked until notified. pub fn wait(self) { - let guard = self.0.lock(); - if *guard.lock_var() { - return; - } - WaitQueue::wait(guard, || {}); + // SAFETY: + // This is only ever called on one thread. + unsafe { Pin::new(&*self.0).park() } } } pub fn new() -> (Notifier, Waiter) { - let inner = Arc::new(SpinMutex::new(WaitVariable::new(false))); + let inner = Arc::new(Parker::new()); (Notifier(inner.clone()), Waiter(inner)) } } diff --git a/library/std/src/sys/sgx/thread_parking.rs b/library/std/src/sys/sgx/thread_parking.rs new file mode 100644 index 000000000..0006cd4f1 --- /dev/null +++ b/library/std/src/sys/sgx/thread_parking.rs @@ -0,0 +1,23 @@ +use super::abi::usercalls; +use crate::io::ErrorKind; +use crate::time::Duration; +use fortanix_sgx_abi::{EV_UNPARK, WAIT_INDEFINITE}; + +pub type ThreadId = fortanix_sgx_abi::Tcs; + +pub use super::abi::thread::current; + +pub fn park(_hint: usize) { + usercalls::wait(EV_UNPARK, WAIT_INDEFINITE).unwrap(); +} + +pub fn park_timeout(dur: Duration, _hint: usize) { + let timeout = u128::min(dur.as_nanos(), WAIT_INDEFINITE as u128 - 1) as u64; + if let Err(e) = usercalls::wait(EV_UNPARK, timeout) { + assert!(matches!(e.kind(), ErrorKind::TimedOut | ErrorKind::WouldBlock)) + } +} + +pub fn unpark(tid: ThreadId, _hint: usize) { + let _ = usercalls::send(EV_UNPARK, Some(tid)); +} diff --git a/library/std/src/sys/unix/android.rs b/library/std/src/sys/unix/android.rs index 73ff10ab8..0f704994f 100644 --- a/library/std/src/sys/unix/android.rs +++ b/library/std/src/sys/unix/android.rs @@ -1,7 +1,7 @@ //! Android ABI-compatibility module //! -//! The ABI of Android has changed quite a bit over time, and libstd attempts to -//! be both forwards and backwards compatible as much as possible. We want to +//! The ABI of Android has changed quite a bit over time, and std attempts to be +//! both forwards and backwards compatible as much as possible. We want to //! always work with the most recent version of Android, but we also want to //! work with older versions of Android for whenever projects need to. //! diff --git a/library/std/src/sys/unix/fs.rs b/library/std/src/sys/unix/fs.rs index 37a49f2d7..8e1f35d6c 100644 --- a/library/std/src/sys/unix/fs.rs +++ b/library/std/src/sys/unix/fs.rs @@ -149,12 +149,13 @@ cfg_has_statx! {{ ) -> Option<io::Result<FileAttr>> { use crate::sync::atomic::{AtomicU8, Ordering}; - // Linux kernel prior to 4.11 or glibc prior to glibc 2.28 don't support `statx` - // We store the availability in global to avoid unnecessary syscalls. - // 0: Unknown - // 1: Not available - // 2: Available - static STATX_STATE: AtomicU8 = AtomicU8::new(0); + // Linux kernel prior to 4.11 or glibc prior to glibc 2.28 don't support `statx`. + // We check for it on first failure and remember availability to avoid having to + // do it again. + #[repr(u8)] + enum STATX_STATE{ Unknown = 0, Present, Unavailable } + static STATX_SAVED_STATE: AtomicU8 = AtomicU8::new(STATX_STATE::Unknown as u8); + syscall! { fn statx( fd: c_int, @@ -165,31 +166,44 @@ cfg_has_statx! {{ ) -> c_int } - match STATX_STATE.load(Ordering::Relaxed) { - 0 => { - // It is a trick to call `statx` with null pointers to check if the syscall - // is available. According to the manual, it is expected to fail with EFAULT. - // We do this mainly for performance, since it is nearly hundreds times - // faster than a normal successful call. - let err = cvt(statx(0, ptr::null(), 0, libc::STATX_ALL, ptr::null_mut())) - .err() - .and_then(|e| e.raw_os_error()); - // We don't check `err == Some(libc::ENOSYS)` because the syscall may be limited - // and returns `EPERM`. Listing all possible errors seems not a good idea. - // See: https://github.com/rust-lang/rust/issues/65662 - if err != Some(libc::EFAULT) { - STATX_STATE.store(1, Ordering::Relaxed); - return None; - } - STATX_STATE.store(2, Ordering::Relaxed); - } - 1 => return None, - _ => {} + if STATX_SAVED_STATE.load(Ordering::Relaxed) == STATX_STATE::Unavailable as u8 { + return None; } let mut buf: libc::statx = mem::zeroed(); if let Err(err) = cvt(statx(fd, path, flags, mask, &mut buf)) { - return Some(Err(err)); + if STATX_SAVED_STATE.load(Ordering::Relaxed) == STATX_STATE::Present as u8 { + return Some(Err(err)); + } + + // Availability not checked yet. + // + // First try the cheap way. + if err.raw_os_error() == Some(libc::ENOSYS) { + STATX_SAVED_STATE.store(STATX_STATE::Unavailable as u8, Ordering::Relaxed); + return None; + } + + // Error other than `ENOSYS` is not a good enough indicator -- it is + // known that `EPERM` can be returned as a result of using seccomp to + // block the syscall. + // Availability is checked by performing a call which expects `EFAULT` + // if the syscall is usable. + // See: https://github.com/rust-lang/rust/issues/65662 + // FIXME this can probably just do the call if `EPERM` was received, but + // previous iteration of the code checked it for all errors and for now + // this is retained. + // FIXME what about transient conditions like `ENOMEM`? + let err2 = cvt(statx(0, ptr::null(), 0, libc::STATX_ALL, ptr::null_mut())) + .err() + .and_then(|e| e.raw_os_error()); + if err2 == Some(libc::EFAULT) { + STATX_SAVED_STATE.store(STATX_STATE::Present as u8, Ordering::Relaxed); + return Some(Err(err)); + } else { + STATX_SAVED_STATE.store(STATX_STATE::Unavailable as u8, Ordering::Relaxed); + return None; + } } // We cannot fill `stat64` exhaustively because of private padding fields. @@ -243,17 +257,15 @@ struct InnerReadDir { pub struct ReadDir { inner: Arc<InnerReadDir>, - #[cfg(not(any( - target_os = "android", - target_os = "linux", - target_os = "solaris", - target_os = "illumos", - target_os = "fuchsia", - target_os = "redox", - )))] end_of_stream: bool, } +impl ReadDir { + fn new(inner: InnerReadDir) -> Self { + Self { inner: Arc::new(inner), end_of_stream: false } + } +} + struct Dir(*mut libc::DIR); unsafe impl Send for Dir {} @@ -332,11 +344,23 @@ pub struct FileTimes { modified: Option<SystemTime>, } -#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)] +#[derive(Copy, Clone, Eq, Debug)] pub struct FileType { mode: mode_t, } +impl PartialEq for FileType { + fn eq(&self, other: &Self) -> bool { + self.masked() == other.masked() + } +} + +impl core::hash::Hash for FileType { + fn hash<H: core::hash::Hasher>(&self, state: &mut H) { + self.masked().hash(state); + } +} + #[derive(Debug)] pub struct DirBuilder { mode: mode_t, @@ -548,7 +572,11 @@ impl FileType { } pub fn is(&self, mode: mode_t) -> bool { - self.mode & libc::S_IFMT == mode + self.masked() == mode + } + + fn masked(&self) -> mode_t { + self.mode & libc::S_IFMT } } @@ -578,18 +606,26 @@ impl Iterator for ReadDir { target_os = "illumos" ))] fn next(&mut self) -> Option<io::Result<DirEntry>> { + if self.end_of_stream { + return None; + } + unsafe { loop { // As of POSIX.1-2017, readdir() is not required to be thread safe; only // readdir_r() is. However, readdir_r() cannot correctly handle platforms - // with unlimited or variable NAME_MAX. Many modern platforms guarantee + // with unlimited or variable NAME_MAX. Many modern platforms guarantee // thread safety for readdir() as long an individual DIR* is not accessed // concurrently, which is sufficient for Rust. super::os::set_errno(0); let entry_ptr = readdir64(self.inner.dirp.0); if entry_ptr.is_null() { - // null can mean either the end is reached or an error occurred. - // So we had to clear errno beforehand to check for an error now. + // We either encountered an error, or reached the end. Either way, + // the next call to next() should return None. + self.end_of_stream = true; + + // To distinguish between errors and end-of-directory, we had to clear + // errno beforehand to check for an error now. return match super::os::errno() { 0 => None, e => Some(Err(Error::from_raw_os_error(e))), @@ -1347,18 +1383,7 @@ pub fn readdir(path: &Path) -> io::Result<ReadDir> { } else { let root = path.to_path_buf(); let inner = InnerReadDir { dirp: Dir(ptr), root }; - Ok(ReadDir { - inner: Arc::new(inner), - #[cfg(not(any( - target_os = "android", - target_os = "linux", - target_os = "solaris", - target_os = "illumos", - target_os = "fuchsia", - target_os = "redox", - )))] - end_of_stream: false, - }) + Ok(ReadDir::new(inner)) } } @@ -1739,12 +1764,16 @@ mod remove_dir_impl { use crate::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd}; use crate::os::unix::prelude::{OwnedFd, RawFd}; use crate::path::{Path, PathBuf}; - use crate::sync::Arc; use crate::sys::common::small_c_string::run_path_with_cstr; use crate::sys::{cvt, cvt_r}; - #[cfg(not(all(target_os = "macos", not(target_arch = "aarch64")),))] + #[cfg(not(any( + all(target_os = "linux", target_env = "gnu"), + all(target_os = "macos", not(target_arch = "aarch64")) + )))] use libc::{fdopendir, openat, unlinkat}; + #[cfg(all(target_os = "linux", target_env = "gnu"))] + use libc::{fdopendir, openat64 as openat, unlinkat}; #[cfg(all(target_os = "macos", not(target_arch = "aarch64")))] use macos_weak::{fdopendir, openat, unlinkat}; @@ -1811,21 +1840,8 @@ mod remove_dir_impl { // a valid root is not needed because we do not call any functions involving the full path // of the DirEntrys. let dummy_root = PathBuf::new(); - Ok(( - ReadDir { - inner: Arc::new(InnerReadDir { dirp, root: dummy_root }), - #[cfg(not(any( - target_os = "android", - target_os = "linux", - target_os = "solaris", - target_os = "illumos", - target_os = "fuchsia", - target_os = "redox", - )))] - end_of_stream: false, - }, - new_parent_fd, - )) + let inner = InnerReadDir { dirp, root: dummy_root }; + Ok((ReadDir::new(inner), new_parent_fd)) } #[cfg(any( diff --git a/library/std/src/sys/unix/kernel_copy.rs b/library/std/src/sys/unix/kernel_copy.rs index 94546ca09..73b9bef7e 100644 --- a/library/std/src/sys/unix/kernel_copy.rs +++ b/library/std/src/sys/unix/kernel_copy.rs @@ -61,6 +61,10 @@ use crate::ptr; use crate::sync::atomic::{AtomicBool, AtomicU8, Ordering}; use crate::sys::cvt; use crate::sys::weak::syscall; +#[cfg(not(all(target_os = "linux", target_env = "gnu")))] +use libc::sendfile as sendfile64; +#[cfg(all(target_os = "linux", target_env = "gnu"))] +use libc::sendfile64; use libc::{EBADF, EINVAL, ENOSYS, EOPNOTSUPP, EOVERFLOW, EPERM, EXDEV}; #[cfg(test)] @@ -583,7 +587,7 @@ pub(super) fn copy_regular_files(reader: RawFd, writer: RawFd, max_len: u64) -> // - copy_file_range file is immutable or syscall is blocked by seccomp¹ (EPERM) // - copy_file_range cannot be used with pipes or device nodes (EINVAL) // - the writer fd was opened with O_APPEND (EBADF²) - // and no bytes were written successfully yet. (All these errnos should + // and no bytes were written successfully yet. (All these errnos should // not be returned if something was already written, but they happen in // the wild, see #91152.) // @@ -647,7 +651,7 @@ fn sendfile_splice(mode: SpliceMode, reader: RawFd, writer: RawFd, len: u64) -> let result = match mode { SpliceMode::Sendfile => { - cvt(unsafe { libc::sendfile(writer, reader, ptr::null_mut(), chunk_size) }) + cvt(unsafe { sendfile64(writer, reader, ptr::null_mut(), chunk_size) }) } SpliceMode::Splice => cvt(unsafe { splice(reader, ptr::null_mut(), writer, ptr::null_mut(), chunk_size, 0) diff --git a/library/std/src/sys/unix/locks/pthread_condvar.rs b/library/std/src/sys/unix/locks/pthread_condvar.rs index 1ddb09905..6be1abc2b 100644 --- a/library/std/src/sys/unix/locks/pthread_condvar.rs +++ b/library/std/src/sys/unix/locks/pthread_condvar.rs @@ -2,6 +2,7 @@ use crate::cell::UnsafeCell; use crate::ptr; use crate::sync::atomic::{AtomicPtr, Ordering::Relaxed}; use crate::sys::locks::{pthread_mutex, Mutex}; +use crate::sys::time::TIMESPEC_MAX; use crate::sys_common::lazy_box::{LazyBox, LazyInit}; use crate::time::Duration; @@ -12,13 +13,6 @@ pub struct Condvar { mutex: AtomicPtr<libc::pthread_mutex_t>, } -const TIMESPEC_MAX: libc::timespec = - libc::timespec { tv_sec: <libc::time_t>::MAX, tv_nsec: 1_000_000_000 - 1 }; - -fn saturating_cast_to_time_t(value: u64) -> libc::time_t { - if value > <libc::time_t>::MAX as u64 { <libc::time_t>::MAX } else { value as libc::time_t } -} - #[inline] fn raw(c: &Condvar) -> *mut libc::pthread_cond_t { c.inner.0.get() @@ -133,26 +127,15 @@ impl Condvar { target_os = "horizon" )))] pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool { - use crate::mem; + use crate::sys::time::Timespec; let mutex = pthread_mutex::raw(mutex); self.verify(mutex); - let mut now: libc::timespec = mem::zeroed(); - let r = libc::clock_gettime(libc::CLOCK_MONOTONIC, &mut now); - assert_eq!(r, 0); - - // Nanosecond calculations can't overflow because both values are below 1e9. - let nsec = dur.subsec_nanos() + now.tv_nsec as u32; - - let sec = saturating_cast_to_time_t(dur.as_secs()) - .checked_add((nsec / 1_000_000_000) as libc::time_t) - .and_then(|s| s.checked_add(now.tv_sec)); - let nsec = nsec % 1_000_000_000; - - let timeout = - sec.map(|s| libc::timespec { tv_sec: s, tv_nsec: nsec as _ }).unwrap_or(TIMESPEC_MAX); - + let timeout = Timespec::now(libc::CLOCK_MONOTONIC) + .checked_add_duration(&dur) + .and_then(|t| t.to_timespec()) + .unwrap_or(TIMESPEC_MAX); let r = libc::pthread_cond_timedwait(raw(self), mutex, &timeout); assert!(r == libc::ETIMEDOUT || r == 0); r == 0 @@ -169,57 +152,41 @@ impl Condvar { target_os = "espidf", target_os = "horizon" ))] - pub unsafe fn wait_timeout(&self, mutex: &Mutex, mut dur: Duration) -> bool { + pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool { + use crate::sys::time::SystemTime; use crate::time::Instant; let mutex = pthread_mutex::raw(mutex); self.verify(mutex); - // 1000 years - let max_dur = Duration::from_secs(1000 * 365 * 86400); - - if dur > max_dur { - // OSX implementation of `pthread_cond_timedwait` is buggy - // with super long durations. When duration is greater than - // 0x100_0000_0000_0000 seconds, `pthread_cond_timedwait` - // in macOS Sierra return error 316. - // - // This program demonstrates the issue: - // https://gist.github.com/stepancheg/198db4623a20aad2ad7cddb8fda4a63c - // - // To work around this issue, and possible bugs of other OSes, timeout - // is clamped to 1000 years, which is allowable per the API of `wait_timeout` - // because of spurious wakeups. - - dur = max_dur; - } - - // First, figure out what time it currently is, in both system and - // stable time. pthread_cond_timedwait uses system time, but we want to - // report timeout based on stable time. - let mut sys_now = libc::timeval { tv_sec: 0, tv_usec: 0 }; - let stable_now = Instant::now(); - let r = libc::gettimeofday(&mut sys_now, ptr::null_mut()); - assert_eq!(r, 0, "unexpected error: {:?}", crate::io::Error::last_os_error()); - - let nsec = dur.subsec_nanos() as libc::c_long + (sys_now.tv_usec * 1000) as libc::c_long; - let extra = (nsec / 1_000_000_000) as libc::time_t; - let nsec = nsec % 1_000_000_000; - let seconds = saturating_cast_to_time_t(dur.as_secs()); - - let timeout = sys_now - .tv_sec - .checked_add(extra) - .and_then(|s| s.checked_add(seconds)) - .map(|s| libc::timespec { tv_sec: s, tv_nsec: nsec }) + // OSX implementation of `pthread_cond_timedwait` is buggy + // with super long durations. When duration is greater than + // 0x100_0000_0000_0000 seconds, `pthread_cond_timedwait` + // in macOS Sierra returns error 316. + // + // This program demonstrates the issue: + // https://gist.github.com/stepancheg/198db4623a20aad2ad7cddb8fda4a63c + // + // To work around this issue, and possible bugs of other OSes, timeout + // is clamped to 1000 years, which is allowable per the API of `wait_timeout` + // because of spurious wakeups. + let dur = Duration::min(dur, Duration::from_secs(1000 * 365 * 86400)); + + // pthread_cond_timedwait uses system time, but we want to report timeout + // based on stable time. + let now = Instant::now(); + + let timeout = SystemTime::now() + .t + .checked_add_duration(&dur) + .and_then(|t| t.to_timespec()) .unwrap_or(TIMESPEC_MAX); - // And wait! let r = libc::pthread_cond_timedwait(raw(self), mutex, &timeout); debug_assert!(r == libc::ETIMEDOUT || r == 0); // ETIMEDOUT is not a totally reliable method of determining timeout due // to clock shifts, so do the check ourselves - stable_now.elapsed() < dur + now.elapsed() < dur } } diff --git a/library/std/src/sys/unix/mod.rs b/library/std/src/sys/unix/mod.rs index 9055a011c..30a96be14 100644 --- a/library/std/src/sys/unix/mod.rs +++ b/library/std/src/sys/unix/mod.rs @@ -40,7 +40,7 @@ pub mod stdio; pub mod thread; pub mod thread_local_dtor; pub mod thread_local_key; -pub mod thread_parker; +pub mod thread_parking; pub mod time; #[cfg(target_os = "espidf")] @@ -95,6 +95,10 @@ pub unsafe fn init(argc: isize, argv: *const *const u8, sigpipe: u8) { )))] 'poll: { use crate::sys::os::errno; + #[cfg(not(all(target_os = "linux", target_env = "gnu")))] + use libc::open as open64; + #[cfg(all(target_os = "linux", target_env = "gnu"))] + use libc::open64; let pfds: &mut [_] = &mut [ libc::pollfd { fd: 0, events: 0, revents: 0 }, libc::pollfd { fd: 1, events: 0, revents: 0 }, @@ -116,7 +120,7 @@ pub unsafe fn init(argc: isize, argv: *const *const u8, sigpipe: u8) { if pfd.revents & libc::POLLNVAL == 0 { continue; } - if libc::open("/dev/null\0".as_ptr().cast(), libc::O_RDWR, 0) == -1 { + if open64("/dev/null\0".as_ptr().cast(), libc::O_RDWR, 0) == -1 { // If the stream is closed but we failed to reopen it, abort the // process. Otherwise we wouldn't preserve the safety of // operations on the corresponding Rust object Stdin, Stdout, or @@ -139,9 +143,13 @@ pub unsafe fn init(argc: isize, argv: *const *const u8, sigpipe: u8) { )))] { use crate::sys::os::errno; + #[cfg(not(all(target_os = "linux", target_env = "gnu")))] + use libc::open as open64; + #[cfg(all(target_os = "linux", target_env = "gnu"))] + use libc::open64; for fd in 0..3 { if libc::fcntl(fd, libc::F_GETFD) == -1 && errno() == libc::EBADF { - if libc::open("/dev/null\0".as_ptr().cast(), libc::O_RDWR, 0) == -1 { + if open64("/dev/null\0".as_ptr().cast(), libc::O_RDWR, 0) == -1 { // If the stream is closed but we failed to reopen it, abort the // process. Otherwise we wouldn't preserve the safety of // operations on the corresponding Rust object Stdin, Stdout, or @@ -156,7 +164,7 @@ pub unsafe fn init(argc: isize, argv: *const *const u8, sigpipe: u8) { unsafe fn reset_sigpipe(#[allow(unused_variables)] sigpipe: u8) { #[cfg(not(any(target_os = "emscripten", target_os = "fuchsia", target_os = "horizon")))] { - // We don't want to add this as a public type to libstd, nor do we + // We don't want to add this as a public type to std, nor do we // want to `include!` a file from the compiler (which would break // Miri and xargo for example), so we choose to duplicate these // constants from `compiler/rustc_session/src/config/sigpipe.rs`. @@ -176,12 +184,7 @@ pub unsafe fn init(argc: isize, argv: *const *const u8, sigpipe: u8) { sigpipe::SIG_DFL => (true, Some(libc::SIG_DFL)), _ => unreachable!(), }; - // The bootstrap compiler doesn't know about sigpipe::DEFAULT, and always passes in - // SIG_IGN. This causes some tests to fail because they expect SIGPIPE to be reset to - // default on process spawning (which doesn't happen if #[unix_sigpipe] is specified). - // Since we can't differentiate between the cases here, treat SIG_IGN as DEFAULT - // unconditionally. - if sigpipe_attr_specified && !(cfg!(bootstrap) && sigpipe == sigpipe::SIG_IGN) { + if sigpipe_attr_specified { UNIX_SIGPIPE_ATTR_SPECIFIED.store(true, crate::sync::atomic::Ordering::Relaxed); } if let Some(handler) = handler { diff --git a/library/std/src/sys/unix/net.rs b/library/std/src/sys/unix/net.rs index b84bf8f92..c86f80972 100644 --- a/library/std/src/sys/unix/net.rs +++ b/library/std/src/sys/unix/net.rs @@ -512,7 +512,7 @@ impl FromRawFd for Socket { // A workaround for this bug is to call the res_init libc function, to clear // the cached configs. Unfortunately, while we believe glibc's implementation // of res_init is thread-safe, we know that other implementations are not -// (https://github.com/rust-lang/rust/issues/43592). Code here in libstd could +// (https://github.com/rust-lang/rust/issues/43592). Code here in std could // try to synchronize its res_init calls with a Mutex, but that wouldn't // protect programs that call into libc in other ways. So instead of calling // res_init unconditionally, we call it only when we detect we're linking diff --git a/library/std/src/sys/unix/pipe.rs b/library/std/src/sys/unix/pipe.rs index a56c275c9..a744d0ab6 100644 --- a/library/std/src/sys/unix/pipe.rs +++ b/library/std/src/sys/unix/pipe.rs @@ -58,6 +58,10 @@ impl AnonPipe { self.0.is_read_vectored() } + pub fn read_to_end(&self, buf: &mut Vec<u8>) -> io::Result<usize> { + self.0.read_to_end(buf) + } + pub fn write(&self, buf: &[u8]) -> io::Result<usize> { self.0.write(buf) } diff --git a/library/std/src/sys/unix/process/process_common.rs b/library/std/src/sys/unix/process/process_common.rs index 848adca78..afd03d79c 100644 --- a/library/std/src/sys/unix/process/process_common.rs +++ b/library/std/src/sys/unix/process/process_common.rs @@ -144,6 +144,7 @@ pub enum ChildStdio { Null, } +#[derive(Debug)] pub enum Stdio { Inherit, Null, @@ -510,16 +511,68 @@ impl ChildStdio { } impl fmt::Debug for Command { + // show all attributes but `self.closures` which does not implement `Debug` + // and `self.argv` which is not useful for debugging fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - if self.program != self.args[0] { - write!(f, "[{:?}] ", self.program)?; - } - write!(f, "{:?}", self.args[0])?; + if f.alternate() { + let mut debug_command = f.debug_struct("Command"); + debug_command.field("program", &self.program).field("args", &self.args); + if !self.env.is_unchanged() { + debug_command.field("env", &self.env); + } + + if self.cwd.is_some() { + debug_command.field("cwd", &self.cwd); + } + if self.uid.is_some() { + debug_command.field("uid", &self.uid); + } + if self.gid.is_some() { + debug_command.field("gid", &self.gid); + } + + if self.groups.is_some() { + debug_command.field("groups", &self.groups); + } + + if self.stdin.is_some() { + debug_command.field("stdin", &self.stdin); + } + if self.stdout.is_some() { + debug_command.field("stdout", &self.stdout); + } + if self.stderr.is_some() { + debug_command.field("stderr", &self.stderr); + } + if self.pgroup.is_some() { + debug_command.field("pgroup", &self.pgroup); + } + + #[cfg(target_os = "linux")] + { + debug_command.field("create_pidfd", &self.create_pidfd); + } - for arg in &self.args[1..] { - write!(f, " {:?}", arg)?; + debug_command.finish() + } else { + if let Some(ref cwd) = self.cwd { + write!(f, "cd {cwd:?} && ")?; + } + for (key, value_opt) in self.get_envs() { + if let Some(value) = value_opt { + write!(f, "{}={value:?} ", key.to_string_lossy())?; + } + } + 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(()) } - Ok(()) } } diff --git a/library/std/src/sys/unix/process/process_fuchsia.rs b/library/std/src/sys/unix/process/process_fuchsia.rs index 66ea3db20..d4c7e58b3 100644 --- a/library/std/src/sys/unix/process/process_fuchsia.rs +++ b/library/std/src/sys/unix/process/process_fuchsia.rs @@ -35,6 +35,11 @@ impl Command { Ok((Process { handle: Handle::new(process_handle) }, ours)) } + pub fn output(&mut self) -> io::Result<(ExitStatus, Vec<u8>, Vec<u8>)> { + let (proc, pipes) = self.spawn(Stdio::MakePipe, false)?; + crate::sys_common::process::wait_with_output(proc, pipes) + } + pub fn exec(&mut self, default: Stdio) -> io::Error { if self.saw_nul() { return io::const_io_error!( @@ -257,7 +262,7 @@ impl ExitStatus { // available on Fuchsia. // // It does not appear that Fuchsia is Unix-like enough to implement ExitStatus (or indeed many - // other things from std::os::unix) properly. This veneer is always going to be a bodge. So + // other things from std::os::unix) properly. This veneer is always going to be a bodge. So // while I don't know if these implementations are actually correct, I think they will do for // now at least. pub fn core_dumped(&self) -> bool { @@ -272,9 +277,9 @@ impl ExitStatus { pub fn into_raw(&self) -> c_int { // We don't know what someone who calls into_raw() will do with this value, but it should - // have the conventional Unix representation. Despite the fact that this is not + // have the conventional Unix representation. Despite the fact that this is not // standardised in SuS or POSIX, all Unix systems encode the signal and exit status the - // same way. (Ie the WIFEXITED, WEXITSTATUS etc. macros have identical behaviour on every + // same way. (Ie the WIFEXITED, WEXITSTATUS etc. macros have identical behaviour on every // Unix.) // // The caller of `std::os::unix::into_raw` is probably wanting a Unix exit status, and may @@ -282,14 +287,14 @@ impl ExitStatus { // different Unix variant. // // The other view would be to say that the caller on Fuchsia ought to know that `into_raw` - // will give a raw Fuchsia status (whatever that is - I don't know, personally). That is + // will give a raw Fuchsia status (whatever that is - I don't know, personally). That is // not possible here because we must return a c_int because that's what Unix (including // SuS and POSIX) say a wait status is, but Fuchsia apparently uses a u64, so it won't // necessarily fit. // // It seems to me that the right answer would be to provide std::os::fuchsia with its // own ExitStatusExt, rather that trying to provide a not very convincing imitation of - // Unix. Ie, std::os::unix::process:ExitStatusExt ought not to exist on Fuchsia. But + // Unix. Ie, std::os::unix::process:ExitStatusExt ought not to exist on Fuchsia. But // fixing this up that is beyond the scope of my efforts now. let exit_status_as_if_unix: u8 = self.0.try_into().expect("Fuchsia process return code bigger than 8 bits, but std::os::unix::ExitStatusExt::into_raw() was called to try to convert the value into a traditional Unix-style wait status, which cannot represent values greater than 255."); let wait_status_as_if_unix = (exit_status_as_if_unix as c_int) << 8; diff --git a/library/std/src/sys/unix/process/process_unix.rs b/library/std/src/sys/unix/process/process_unix.rs index 56a805cef..3bc17b775 100644 --- a/library/std/src/sys/unix/process/process_unix.rs +++ b/library/std/src/sys/unix/process/process_unix.rs @@ -66,14 +66,15 @@ impl Command { // // Note that as soon as we're done with the fork there's no need to hold // a lock any more because the parent won't do anything and the child is - // in its own process. Thus the parent drops the lock guard while the child - // forgets it to avoid unlocking it on a new thread, which would be invalid. + // in its own process. Thus the parent drops the lock guard immediately. + // The child calls `mem::forget` to leak the lock, which is crucial because + // releasing a lock is not async-signal-safe. let env_lock = sys::os::env_read_lock(); let (pid, pidfd) = unsafe { self.do_fork()? }; if pid == 0 { crate::panic::always_abort(); - mem::forget(env_lock); + mem::forget(env_lock); // avoid non-async-signal-safe unlocking drop(input); let Err(err) = unsafe { self.do_exec(theirs, envp.as_ref()) }; let errno = err.raw_os_error().unwrap_or(libc::EINVAL) as u32; @@ -132,6 +133,11 @@ impl Command { } } + pub fn output(&mut self) -> io::Result<(ExitStatus, Vec<u8>, Vec<u8>)> { + let (proc, pipes) = self.spawn(Stdio::MakePipe, false)?; + crate::sys_common::process::wait_with_output(proc, pipes) + } + // Attempts to fork the process. If successful, returns Ok((0, -1)) // in the child, and Ok((child_pid, -1)) in the parent. #[cfg(not(target_os = "linux"))] @@ -660,11 +666,11 @@ impl ExitStatus { } pub fn exit_ok(&self) -> Result<(), ExitStatusError> { - // This assumes that WIFEXITED(status) && WEXITSTATUS==0 corresponds to status==0. This is + // This assumes that WIFEXITED(status) && WEXITSTATUS==0 corresponds to status==0. This is // true on all actual versions of Unix, is widely assumed, and is specified in SuS - // https://pubs.opengroup.org/onlinepubs/9699919799/functions/wait.html . If it is not + // https://pubs.opengroup.org/onlinepubs/9699919799/functions/wait.html. If it is not // true for a platform pretending to be Unix, the tests (our doctests, and also - // procsss_unix/tests.rs) will spot it. `ExitStatusError::code` assumes this too. + // procsss_unix/tests.rs) will spot it. `ExitStatusError::code` assumes this too. match NonZero_c_int::try_from(self.0) { /* was nonzero */ Ok(failure) => Err(ExitStatusError(failure)), /* was zero, couldn't convert */ Err(_) => Ok(()), @@ -740,6 +746,8 @@ fn signal_string(signal: i32) -> &'static str { libc::SIGWINCH => " (SIGWINCH)", #[cfg(not(target_os = "haiku"))] libc::SIGIO => " (SIGIO)", + #[cfg(target_os = "haiku")] + libc::SIGPOLL => " (SIGPOLL)", libc::SIGSYS => " (SIGSYS)", // For information on Linux signals, run `man 7 signal` #[cfg(all( diff --git a/library/std/src/sys/unix/process/process_unix/tests.rs b/library/std/src/sys/unix/process/process_unix/tests.rs index e0e2d478f..e5e1f956b 100644 --- a/library/std/src/sys/unix/process/process_unix/tests.rs +++ b/library/std/src/sys/unix/process/process_unix/tests.rs @@ -3,7 +3,7 @@ use crate::panic::catch_unwind; use crate::process::Command; // Many of the other aspects of this situation, including heap alloc concurrency -// safety etc., are tested in src/test/ui/process/process-panic-after-fork.rs +// safety etc., are tested in tests/ui/process/process-panic-after-fork.rs #[test] fn exitstatus_display_tests() { @@ -19,17 +19,17 @@ fn exitstatus_display_tests() { t(0x00000, "exit status: 0"); t(0x0ff00, "exit status: 255"); - // On MacOS, 0x0137f is WIFCONTINUED, not WIFSTOPPED. Probably *BSD is similar. + // On MacOS, 0x0137f is WIFCONTINUED, not WIFSTOPPED. Probably *BSD is similar. // https://github.com/rust-lang/rust/pull/82749#issuecomment-790525956 // The purpose of this test is to test our string formatting, not our understanding of the wait - // status magic numbers. So restrict these to Linux. + // status magic numbers. So restrict these to Linux. if cfg!(target_os = "linux") { t(0x0137f, "stopped (not terminated) by signal: 19 (SIGSTOP)"); t(0x0ffff, "continued (WIFCONTINUED)"); } // Testing "unrecognised wait status" is hard because the wait.h macros typically - // assume that the value came from wait and isn't mad. With the glibc I have here + // assume that the value came from wait and isn't mad. With the glibc I have here // this works: if cfg!(all(target_os = "linux", target_env = "gnu")) { t(0x000ff, "unrecognised wait status: 255 0xff"); diff --git a/library/std/src/sys/unix/process/process_unsupported.rs b/library/std/src/sys/unix/process/process_unsupported.rs index 72f9f3f9c..f28ca58d0 100644 --- a/library/std/src/sys/unix/process/process_unsupported.rs +++ b/library/std/src/sys/unix/process/process_unsupported.rs @@ -20,6 +20,10 @@ impl Command { unsupported() } + pub fn output(&mut self) -> io::Result<(ExitStatus, Vec<u8>, Vec<u8>)> { + unsupported() + } + pub fn exec(&mut self, _default: Stdio) -> io::Error { unsupported_err() } diff --git a/library/std/src/sys/unix/process/process_vxworks.rs b/library/std/src/sys/unix/process/process_vxworks.rs index 200ef6719..569a4b149 100644 --- a/library/std/src/sys/unix/process/process_vxworks.rs +++ b/library/std/src/sys/unix/process/process_vxworks.rs @@ -108,6 +108,11 @@ impl Command { } } + pub fn output(&mut self) -> io::Result<(ExitStatus, Vec<u8>, Vec<u8>)> { + let (proc, pipes) = self.spawn(Stdio::MakePipe, false)?; + crate::sys_common::process::wait_with_output(proc, pipes) + } + pub fn exec(&mut self, default: Stdio) -> io::Error { let ret = Command::spawn(self, default, false); match ret { @@ -190,11 +195,11 @@ impl ExitStatus { } pub fn exit_ok(&self) -> Result<(), ExitStatusError> { - // This assumes that WIFEXITED(status) && WEXITSTATUS==0 corresponds to status==0. This is + // This assumes that WIFEXITED(status) && WEXITSTATUS==0 corresponds to status==0. This is // true on all actual versions of Unix, is widely assumed, and is specified in SuS - // https://pubs.opengroup.org/onlinepubs/9699919799/functions/wait.html . If it is not + // https://pubs.opengroup.org/onlinepubs/9699919799/functions/wait.html. If it is not // true for a platform pretending to be Unix, the tests (our doctests, and also - // procsss_unix/tests.rs) will spot it. `ExitStatusError::code` assumes this too. + // procsss_unix/tests.rs) will spot it. `ExitStatusError::code` assumes this too. match NonZero_c_int::try_from(self.0) { Ok(failure) => Err(ExitStatusError(failure)), Err(_) => Ok(()), diff --git a/library/std/src/sys/unix/stack_overflow.rs b/library/std/src/sys/unix/stack_overflow.rs index 75a5c0f92..b59d4ba26 100644 --- a/library/std/src/sys/unix/stack_overflow.rs +++ b/library/std/src/sys/unix/stack_overflow.rs @@ -45,7 +45,10 @@ mod imp { use crate::thread; use libc::MAP_FAILED; - use libc::{mmap, munmap}; + #[cfg(not(all(target_os = "linux", target_env = "gnu")))] + use libc::{mmap as mmap64, munmap}; + #[cfg(all(target_os = "linux", target_env = "gnu"))] + use libc::{mmap64, munmap}; use libc::{sigaction, sighandler_t, SA_ONSTACK, SA_SIGINFO, SIGBUS, SIG_DFL}; use libc::{sigaltstack, SIGSTKSZ, SS_DISABLE}; use libc::{MAP_ANON, MAP_PRIVATE, PROT_NONE, PROT_READ, PROT_WRITE, SIGSEGV}; @@ -135,7 +138,7 @@ mod imp { #[cfg(not(any(target_os = "openbsd", target_os = "netbsd", target_os = "linux",)))] let flags = MAP_PRIVATE | MAP_ANON; let stackp = - mmap(ptr::null_mut(), SIGSTKSZ + page_size(), PROT_READ | PROT_WRITE, flags, -1, 0); + mmap64(ptr::null_mut(), SIGSTKSZ + page_size(), PROT_READ | PROT_WRITE, flags, -1, 0); if stackp == MAP_FAILED { panic!("failed to allocate an alternative stack: {}", io::Error::last_os_error()); } diff --git a/library/std/src/sys/unix/thread.rs b/library/std/src/sys/unix/thread.rs index c1d30dd9d..2a1830d06 100644 --- a/library/std/src/sys/unix/thread.rs +++ b/library/std/src/sys/unix/thread.rs @@ -73,7 +73,7 @@ impl Thread { n => { assert_eq!(n, libc::EINVAL); // EINVAL means |stack_size| is either too small or not a - // multiple of the system page size. Because it's definitely + // multiple of the system page size. Because it's definitely // >= PTHREAD_STACK_MIN, it must be an alignment issue. // Round up to the nearest page and try again. let page_size = os::page_size(); @@ -136,7 +136,7 @@ impl Thread { unsafe { // Available since glibc 2.12, musl 1.1.16, and uClibc 1.0.20. - let name = truncate_cstr(name, TASK_COMM_LEN); + let name = truncate_cstr::<{ TASK_COMM_LEN }>(name); let res = libc::pthread_setname_np(libc::pthread_self(), name.as_ptr()); // We have no good way of propagating errors here, but in debug-builds let's check that this actually worked. debug_assert_eq!(res, 0); @@ -153,7 +153,7 @@ impl Thread { #[cfg(any(target_os = "macos", target_os = "ios", target_os = "watchos"))] pub fn set_name(name: &CStr) { unsafe { - let name = truncate_cstr(name, libc::MAXTHREADNAMESIZE); + let name = truncate_cstr::<{ libc::MAXTHREADNAMESIZE }>(name); let res = libc::pthread_setname_np(name.as_ptr()); // We have no good way of propagating errors here, but in debug-builds let's check that this actually worked. debug_assert_eq!(res, 0); @@ -285,17 +285,12 @@ impl Drop for Thread { } #[cfg(any(target_os = "linux", target_os = "macos", target_os = "ios", target_os = "watchos"))] -fn truncate_cstr(cstr: &CStr, max_with_nul: usize) -> crate::borrow::Cow<'_, CStr> { - use crate::{borrow::Cow, ffi::CString}; - - if cstr.to_bytes_with_nul().len() > max_with_nul { - let bytes = cstr.to_bytes()[..max_with_nul - 1].to_vec(); - // SAFETY: the non-nul bytes came straight from a CStr. - // (CString will add the terminating nul.) - Cow::Owned(unsafe { CString::from_vec_unchecked(bytes) }) - } else { - Cow::Borrowed(cstr) +fn truncate_cstr<const MAX_WITH_NUL: usize>(cstr: &CStr) -> [libc::c_char; MAX_WITH_NUL] { + let mut result = [0; MAX_WITH_NUL]; + for (src, dst) in cstr.to_bytes().iter().zip(&mut result[..MAX_WITH_NUL - 1]) { + *dst = *src as libc::c_char; } + result } pub fn available_parallelism() -> io::Result<NonZeroUsize> { @@ -510,7 +505,7 @@ mod cgroups { let limit = raw_quota.next()?; let period = raw_quota.next()?; match (limit.parse::<usize>(), period.parse::<usize>()) { - (Ok(limit), Ok(period)) => { + (Ok(limit), Ok(period)) if period > 0 => { quota = quota.min(limit / period); } _ => {} @@ -570,7 +565,7 @@ mod cgroups { let period = parse_file("cpu.cfs_period_us"); match (limit, period) { - (Some(limit), Some(period)) => quota = quota.min(limit / period), + (Some(limit), Some(period)) if period > 0 => quota = quota.min(limit / period), _ => {} } @@ -658,7 +653,10 @@ pub mod guard { ))] #[cfg_attr(test, allow(dead_code))] pub mod guard { - use libc::{mmap, mprotect}; + #[cfg(not(all(target_os = "linux", target_env = "gnu")))] + use libc::{mmap as mmap64, mprotect}; + #[cfg(all(target_os = "linux", target_env = "gnu"))] + use libc::{mmap64, mprotect}; use libc::{MAP_ANON, MAP_FAILED, MAP_FIXED, MAP_PRIVATE, PROT_NONE, PROT_READ, PROT_WRITE}; use crate::io; @@ -757,10 +755,10 @@ pub mod guard { if cfg!(all(target_os = "linux", not(target_env = "musl"))) { // Linux doesn't allocate the whole stack right away, and // the kernel has its own stack-guard mechanism to fault - // when growing too close to an existing mapping. If we map + // when growing too close to an existing mapping. If we map // our own guard, then the kernel starts enforcing a rather // large gap above that, rendering much of the possible - // stack space useless. See #43052. + // stack space useless. See #43052. // // Instead, we'll just note where we expect rlimit to start // faulting, so our handler can report "stack overflow", and @@ -776,14 +774,14 @@ pub mod guard { None } else if cfg!(target_os = "freebsd") { // FreeBSD's stack autogrows, and optionally includes a guard page - // at the bottom. If we try to remap the bottom of the stack - // ourselves, FreeBSD's guard page moves upwards. So we'll just use + // at the bottom. If we try to remap the bottom of the stack + // ourselves, FreeBSD's guard page moves upwards. So we'll just use // the builtin guard page. let stackptr = get_stack_start_aligned()?; let guardaddr = stackptr.addr(); // Technically the number of guard pages is tunable and controlled // by the security.bsd.stack_guard_page sysctl, but there are - // few reasons to change it from the default. The default value has + // few reasons to change it from the default. The default value has // been 1 ever since FreeBSD 11.1 and 10.4. const GUARD_PAGES: usize = 1; let guard = guardaddr..guardaddr + GUARD_PAGES * page_size; @@ -808,7 +806,7 @@ pub mod guard { // read/write permissions and only then mprotect() it to // no permissions at all. See issue #50313. let stackptr = get_stack_start_aligned()?; - let result = mmap( + let result = mmap64( stackptr, page_size, PROT_READ | PROT_WRITE, @@ -879,9 +877,9 @@ pub mod guard { } else if cfg!(all(target_os = "linux", any(target_env = "gnu", target_env = "uclibc"))) { // glibc used to include the guard area within the stack, as noted in the BUGS - // section of `man pthread_attr_getguardsize`. This has been corrected starting + // section of `man pthread_attr_getguardsize`. This has been corrected starting // with glibc 2.27, and in some distro backports, so the guard is now placed at the - // end (below) the stack. There's no easy way for us to know which we have at + // end (below) the stack. There's no easy way for us to know which we have at // runtime, so we'll just match any fault in the range right above or below the // stack base to call that fault a stack overflow. Some(stackaddr - guardsize..stackaddr + guardsize) diff --git a/library/std/src/sys/unix/thread_parker/mod.rs b/library/std/src/sys/unix/thread_parker/mod.rs deleted file mode 100644 index 35f1e68a8..000000000 --- a/library/std/src/sys/unix/thread_parker/mod.rs +++ /dev/null @@ -1,32 +0,0 @@ -//! Thread parking on systems without futex support. - -#![cfg(not(any( - target_os = "linux", - target_os = "android", - all(target_os = "emscripten", target_feature = "atomics"), - target_os = "freebsd", - target_os = "openbsd", - target_os = "dragonfly", - target_os = "fuchsia", -)))] - -cfg_if::cfg_if! { - if #[cfg(all( - any( - target_os = "macos", - target_os = "ios", - target_os = "watchos", - target_os = "tvos", - ), - not(miri), - ))] { - mod darwin; - pub use darwin::Parker; - } else if #[cfg(target_os = "netbsd")] { - mod netbsd; - pub use netbsd::Parker; - } else { - mod pthread; - pub use pthread::Parker; - } -} diff --git a/library/std/src/sys/unix/thread_parker/netbsd.rs b/library/std/src/sys/unix/thread_parker/netbsd.rs deleted file mode 100644 index 7657605b5..000000000 --- a/library/std/src/sys/unix/thread_parker/netbsd.rs +++ /dev/null @@ -1,113 +0,0 @@ -use crate::ffi::{c_int, c_void}; -use crate::pin::Pin; -use crate::ptr::{null, null_mut}; -use crate::sync::atomic::{ - AtomicU64, - Ordering::{Acquire, Relaxed, Release}, -}; -use crate::time::Duration; -use libc::{_lwp_self, clockid_t, lwpid_t, time_t, timespec, CLOCK_MONOTONIC}; - -extern "C" { - fn ___lwp_park60( - clock_id: clockid_t, - flags: c_int, - ts: *mut timespec, - unpark: lwpid_t, - hint: *const c_void, - unparkhint: *const c_void, - ) -> c_int; - fn _lwp_unpark(lwp: lwpid_t, hint: *const c_void) -> c_int; -} - -/// The thread is not parked and the token is not available. -/// -/// Zero cannot be a valid LWP id, since it is used as empty value for the unpark -/// argument in _lwp_park. -const EMPTY: u64 = 0; -/// The token is available. Do not park anymore. -const NOTIFIED: u64 = u64::MAX; - -pub struct Parker { - /// The parker state. Contains either one of the two state values above or the LWP - /// id of the parked thread. - state: AtomicU64, -} - -impl Parker { - pub unsafe fn new(parker: *mut Parker) { - parker.write(Parker { state: AtomicU64::new(EMPTY) }) - } - - // Does not actually need `unsafe` or `Pin`, but the pthread implementation does. - pub unsafe fn park(self: Pin<&Self>) { - // If the token has already been made available, we can skip - // a bit of work, so check for it here. - if self.state.load(Acquire) != NOTIFIED { - let parked = _lwp_self() as u64; - let hint = self.state.as_mut_ptr().cast(); - if self.state.compare_exchange(EMPTY, parked, Relaxed, Acquire).is_ok() { - // Loop to guard against spurious wakeups. - loop { - ___lwp_park60(0, 0, null_mut(), 0, hint, null()); - if self.state.load(Acquire) == NOTIFIED { - break; - } - } - } - } - - // At this point, the change to NOTIFIED has always been observed with acquire - // ordering, so we can just use a relaxed store here (instead of a swap). - self.state.store(EMPTY, Relaxed); - } - - // Does not actually need `unsafe` or `Pin`, but the pthread implementation does. - pub unsafe fn park_timeout(self: Pin<&Self>, dur: Duration) { - if self.state.load(Acquire) != NOTIFIED { - let parked = _lwp_self() as u64; - let hint = self.state.as_mut_ptr().cast(); - let mut timeout = timespec { - // Saturate so that the operation will definitely time out - // (even if it is after the heat death of the universe). - tv_sec: dur.as_secs().try_into().ok().unwrap_or(time_t::MAX), - tv_nsec: dur.subsec_nanos().into(), - }; - - if self.state.compare_exchange(EMPTY, parked, Relaxed, Acquire).is_ok() { - // Timeout needs to be mutable since it is modified on NetBSD 9.0 and - // above. - ___lwp_park60(CLOCK_MONOTONIC, 0, &mut timeout, 0, hint, null()); - // Use a swap to get acquire ordering even if the token was set after - // the timeout occurred. - self.state.swap(EMPTY, Acquire); - return; - } - } - - self.state.store(EMPTY, Relaxed); - } - - // Does not actually need `Pin`, but the pthread implementation does. - pub fn unpark(self: Pin<&Self>) { - let state = self.state.swap(NOTIFIED, Release); - if !matches!(state, EMPTY | NOTIFIED) { - let lwp = state as lwpid_t; - let hint = self.state.as_mut_ptr().cast(); - - // If the parking thread terminated and did not actually park, this will - // probably return an error, which is OK. In the worst case, another - // thread has received the same LWP id. It will then receive a spurious - // wakeup, but those are allowable per the API contract. The same reasoning - // applies if a timeout occurred before this call, but the state was not - // yet reset. - - // SAFETY: - // The syscall has no invariants to hold. Only unsafe because it is an - // extern function. - unsafe { - _lwp_unpark(lwp, hint); - } - } - } -} diff --git a/library/std/src/sys/unix/thread_parker/darwin.rs b/library/std/src/sys/unix/thread_parking/darwin.rs index 2f5356fe2..b709fada3 100644 --- a/library/std/src/sys/unix/thread_parker/darwin.rs +++ b/library/std/src/sys/unix/thread_parking/darwin.rs @@ -46,7 +46,7 @@ unsafe impl Sync for Parker {} unsafe impl Send for Parker {} impl Parker { - pub unsafe fn new(parker: *mut Parker) { + pub unsafe fn new_in_place(parker: *mut Parker) { let semaphore = dispatch_semaphore_create(0); assert!( !semaphore.is_null(), diff --git a/library/std/src/sys/unix/thread_parking/mod.rs b/library/std/src/sys/unix/thread_parking/mod.rs new file mode 100644 index 000000000..185333c07 --- /dev/null +++ b/library/std/src/sys/unix/thread_parking/mod.rs @@ -0,0 +1,32 @@ +//! Thread parking on systems without futex support. + +#![cfg(not(any( + target_os = "linux", + target_os = "android", + all(target_os = "emscripten", target_feature = "atomics"), + target_os = "freebsd", + target_os = "openbsd", + target_os = "dragonfly", + target_os = "fuchsia", +)))] + +cfg_if::cfg_if! { + if #[cfg(all( + any( + target_os = "macos", + target_os = "ios", + target_os = "watchos", + target_os = "tvos", + ), + not(miri), + ))] { + mod darwin; + pub use darwin::Parker; + } else if #[cfg(target_os = "netbsd")] { + mod netbsd; + pub use netbsd::{current, park, park_timeout, unpark, ThreadId}; + } else { + mod pthread; + pub use pthread::Parker; + } +} diff --git a/library/std/src/sys/unix/thread_parking/netbsd.rs b/library/std/src/sys/unix/thread_parking/netbsd.rs new file mode 100644 index 000000000..3be081221 --- /dev/null +++ b/library/std/src/sys/unix/thread_parking/netbsd.rs @@ -0,0 +1,52 @@ +use crate::ffi::{c_int, c_void}; +use crate::ptr; +use crate::time::Duration; +use libc::{_lwp_self, clockid_t, lwpid_t, time_t, timespec, CLOCK_MONOTONIC}; + +extern "C" { + fn ___lwp_park60( + clock_id: clockid_t, + flags: c_int, + ts: *mut timespec, + unpark: lwpid_t, + hint: *const c_void, + unparkhint: *const c_void, + ) -> c_int; + fn _lwp_unpark(lwp: lwpid_t, hint: *const c_void) -> c_int; +} + +pub type ThreadId = lwpid_t; + +#[inline] +pub fn current() -> ThreadId { + unsafe { _lwp_self() } +} + +#[inline] +pub fn park(hint: usize) { + unsafe { + ___lwp_park60(0, 0, ptr::null_mut(), 0, ptr::invalid(hint), ptr::null()); + } +} + +pub fn park_timeout(dur: Duration, hint: usize) { + let mut timeout = timespec { + // Saturate so that the operation will definitely time out + // (even if it is after the heat death of the universe). + tv_sec: dur.as_secs().try_into().ok().unwrap_or(time_t::MAX), + tv_nsec: dur.subsec_nanos().into(), + }; + + // Timeout needs to be mutable since it is modified on NetBSD 9.0 and + // above. + unsafe { + ___lwp_park60(CLOCK_MONOTONIC, 0, &mut timeout, 0, ptr::invalid(hint), ptr::null()); + } +} + +#[inline] +pub fn unpark(tid: ThreadId, hint: usize) { + unsafe { + _lwp_unpark(tid, ptr::invalid(hint)); + } +} diff --git a/library/std/src/sys/unix/thread_parker/pthread.rs b/library/std/src/sys/unix/thread_parking/pthread.rs index 3dfc0026e..082d25e68 100644 --- a/library/std/src/sys/unix/thread_parker/pthread.rs +++ b/library/std/src/sys/unix/thread_parking/pthread.rs @@ -6,6 +6,7 @@ use crate::pin::Pin; use crate::ptr::addr_of_mut; use crate::sync::atomic::AtomicUsize; use crate::sync::atomic::Ordering::SeqCst; +use crate::sys::time::TIMESPEC_MAX; use crate::time::Duration; const EMPTY: usize = 0; @@ -32,9 +33,6 @@ unsafe fn wait(cond: *mut libc::pthread_cond_t, lock: *mut libc::pthread_mutex_t debug_assert_eq!(r, 0); } -const TIMESPEC_MAX: libc::timespec = - libc::timespec { tv_sec: <libc::time_t>::MAX, tv_nsec: 1_000_000_000 - 1 }; - unsafe fn wait_timeout( cond: *mut libc::pthread_cond_t, lock: *mut libc::pthread_mutex_t, @@ -46,7 +44,8 @@ unsafe fn wait_timeout( target_os = "macos", target_os = "ios", target_os = "watchos", - target_os = "espidf" + target_os = "espidf", + target_os = "horizon", ))] let (now, dur) = { use crate::cmp::min; @@ -72,7 +71,8 @@ unsafe fn wait_timeout( target_os = "macos", target_os = "ios", target_os = "watchos", - target_os = "espidf" + target_os = "espidf", + target_os = "horizon", )))] let (now, dur) = { use crate::sys::time::Timespec; @@ -99,7 +99,7 @@ impl Parker { /// /// # Safety /// The constructed parker must never be moved. - pub unsafe fn new(parker: *mut Parker) { + pub unsafe fn new_in_place(parker: *mut Parker) { // Use the default mutex implementation to allow for simpler initialization. // This could lead to undefined behaviour when deadlocking. This is avoided // by not deadlocking. Note in particular the unlocking operation before any diff --git a/library/std/src/sys/unix/time.rs b/library/std/src/sys/unix/time.rs index d5abd9b58..2daad981b 100644 --- a/library/std/src/sys/unix/time.rs +++ b/library/std/src/sys/unix/time.rs @@ -5,6 +5,9 @@ pub use self::inner::Instant; const NSEC_PER_SEC: u64 = 1_000_000_000; pub const UNIX_EPOCH: SystemTime = SystemTime { t: Timespec::zero() }; +#[allow(dead_code)] // Used for pthread condvar timeouts +pub const TIMESPEC_MAX: libc::timespec = + libc::timespec { tv_sec: <libc::time_t>::MAX, tv_nsec: 1_000_000_000 - 1 }; #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] #[repr(transparent)] diff --git a/library/std/src/sys/unix/weak.rs b/library/std/src/sys/unix/weak.rs index f5a4ce929..62ffee70b 100644 --- a/library/std/src/sys/unix/weak.rs +++ b/library/std/src/sys/unix/weak.rs @@ -1,9 +1,8 @@ //! Support for "weak linkage" to symbols on Unix //! -//! Some I/O operations we do in libstd require newer versions of OSes but we -//! need to maintain binary compatibility with older releases for now. In order -//! to use the new functionality when available we use this module for -//! detection. +//! Some I/O operations we do in std require newer versions of OSes but we need +//! to maintain binary compatibility with older releases for now. In order to +//! use the new functionality when available we use this module for detection. //! //! One option to use here is weak linkage, but that is unfortunately only //! really workable with ELF. Otherwise, use dlsym to get the symbol value at @@ -29,7 +28,7 @@ use crate::ptr; use crate::sync::atomic::{self, AtomicPtr, Ordering}; // We can use true weak linkage on ELF targets. -#[cfg(all(not(any(target_os = "macos", target_os = "ios")), not(bootstrap)))] +#[cfg(not(any(target_os = "macos", target_os = "ios")))] pub(crate) macro weak { (fn $name:ident($($t:ty),*) -> $ret:ty) => ( let ref $name: ExternWeak<unsafe extern "C" fn($($t),*) -> $ret> = { @@ -43,30 +42,14 @@ pub(crate) macro weak { ) } -#[cfg(all(not(any(target_os = "macos", target_os = "ios")), bootstrap))] -pub(crate) macro weak { - (fn $name:ident($($t:ty),*) -> $ret:ty) => ( - let ref $name: ExternWeak<unsafe extern "C" fn($($t),*) -> $ret> = { - extern "C" { - #[linkage = "extern_weak"] - static $name: *const libc::c_void; - } - #[allow(unused_unsafe)] - ExternWeak::new(unsafe { $name }) - }; - ) -} - // On non-ELF targets, use the dlsym approximation of weak linkage. #[cfg(any(target_os = "macos", target_os = "ios"))] pub(crate) use self::dlsym as weak; -#[cfg(not(bootstrap))] pub(crate) struct ExternWeak<F: Copy> { weak_ptr: Option<F>, } -#[cfg(not(bootstrap))] impl<F: Copy> ExternWeak<F> { #[inline] pub(crate) fn new(weak_ptr: Option<F>) -> Self { @@ -79,34 +62,6 @@ impl<F: Copy> ExternWeak<F> { } } -#[cfg(bootstrap)] -pub(crate) struct ExternWeak<F> { - weak_ptr: *const libc::c_void, - _marker: PhantomData<F>, -} - -#[cfg(bootstrap)] -impl<F> ExternWeak<F> { - #[inline] - pub(crate) fn new(weak_ptr: *const libc::c_void) -> Self { - ExternWeak { weak_ptr, _marker: PhantomData } - } -} - -#[cfg(bootstrap)] -impl<F> ExternWeak<F> { - #[inline] - pub(crate) fn get(&self) -> Option<F> { - unsafe { - if self.weak_ptr.is_null() { - None - } else { - Some(mem::transmute_copy::<*const libc::c_void, F>(&self.weak_ptr)) - } - } - } -} - pub(crate) macro dlsym { (fn $name:ident($($t:ty),*) -> $ret:ty) => ( dlsym!(fn $name($($t),*) -> $ret, stringify!($name)); diff --git a/library/std/src/sys/unsupported/mod.rs b/library/std/src/sys/unsupported/mod.rs index 7bf6d40b7..15b22c620 100644 --- a/library/std/src/sys/unsupported/mod.rs +++ b/library/std/src/sys/unsupported/mod.rs @@ -9,6 +9,7 @@ pub mod fs; pub mod io; pub mod locks; pub mod net; +pub mod once; pub mod os; #[path = "../unix/os_str.rs"] pub mod os_str; diff --git a/library/std/src/sys/unsupported/once.rs b/library/std/src/sys/unsupported/once.rs new file mode 100644 index 000000000..b4bb4975f --- /dev/null +++ b/library/std/src/sys/unsupported/once.rs @@ -0,0 +1,89 @@ +use crate::cell::Cell; +use crate::sync as public; + +pub struct Once { + state: Cell<State>, +} + +pub struct OnceState { + poisoned: bool, + set_state_to: Cell<State>, +} + +#[derive(Clone, Copy, PartialEq, Eq)] +enum State { + Incomplete, + Poisoned, + Running, + Complete, +} + +struct CompletionGuard<'a> { + state: &'a Cell<State>, + set_state_on_drop_to: State, +} + +impl<'a> Drop for CompletionGuard<'a> { + fn drop(&mut self) { + self.state.set(self.set_state_on_drop_to); + } +} + +// Safety: threads are not supported on this platform. +unsafe impl Sync for Once {} + +impl Once { + #[inline] + #[rustc_const_stable(feature = "const_once_new", since = "1.32.0")] + pub const fn new() -> Once { + Once { state: Cell::new(State::Incomplete) } + } + + #[inline] + pub fn is_completed(&self) -> bool { + self.state.get() == State::Complete + } + + #[cold] + #[track_caller] + pub fn call(&self, ignore_poisoning: bool, f: &mut impl FnMut(&public::OnceState)) { + let state = self.state.get(); + match state { + State::Poisoned if !ignore_poisoning => { + // Panic to propagate the poison. + panic!("Once instance has previously been poisoned"); + } + State::Incomplete | State::Poisoned => { + self.state.set(State::Running); + // `guard` will set the new state on drop. + let mut guard = + CompletionGuard { state: &self.state, set_state_on_drop_to: State::Poisoned }; + // Run the function, letting it know if we're poisoned or not. + let f_state = public::OnceState { + inner: OnceState { + poisoned: state == State::Poisoned, + set_state_to: Cell::new(State::Complete), + }, + }; + f(&f_state); + guard.set_state_on_drop_to = f_state.inner.set_state_to.get(); + } + State::Running => { + panic!("one-time initialization may not be performed recursively"); + } + State::Complete => {} + } + } +} + +impl OnceState { + #[inline] + pub fn is_poisoned(&self) -> bool { + self.poisoned + } + + #[inline] + pub fn poison(&self) { + self.set_state_to.set(State::Poisoned) + } +} diff --git a/library/std/src/sys/unsupported/pipe.rs b/library/std/src/sys/unsupported/pipe.rs index 25514c232..0bba673b4 100644 --- a/library/std/src/sys/unsupported/pipe.rs +++ b/library/std/src/sys/unsupported/pipe.rs @@ -15,6 +15,10 @@ impl AnonPipe { self.0 } + pub fn read_to_end(&self, _buf: &mut Vec<u8>) -> io::Result<usize> { + self.0 + } + pub fn write(&self, _buf: &[u8]) -> io::Result<usize> { self.0 } diff --git a/library/std/src/sys/unsupported/process.rs b/library/std/src/sys/unsupported/process.rs index 633f17c05..a494f2d6b 100644 --- a/library/std/src/sys/unsupported/process.rs +++ b/library/std/src/sys/unsupported/process.rs @@ -75,6 +75,10 @@ impl Command { ) -> io::Result<(Process, StdioPipes)> { unsupported() } + + pub fn output(&mut self) -> io::Result<(ExitStatus, Vec<u8>, Vec<u8>)> { + unsupported() + } } impl From<AnonPipe> for Stdio { diff --git a/library/std/src/sys/wasi/mod.rs b/library/std/src/sys/wasi/mod.rs index c8c47763a..1dc3f2b20 100644 --- a/library/std/src/sys/wasi/mod.rs +++ b/library/std/src/sys/wasi/mod.rs @@ -32,6 +32,8 @@ pub mod io; #[path = "../unsupported/locks/mod.rs"] pub mod locks; pub mod net; +#[path = "../unsupported/once.rs"] +pub mod once; pub mod os; #[path = "../unix/os_str.rs"] pub mod os_str; diff --git a/library/std/src/sys/wasm/mod.rs b/library/std/src/sys/wasm/mod.rs index d68c3e5f1..77ebe3c4a 100644 --- a/library/std/src/sys/wasm/mod.rs +++ b/library/std/src/sys/wasm/mod.rs @@ -66,6 +66,8 @@ cfg_if::cfg_if! { } else { #[path = "../unsupported/locks/mod.rs"] pub mod locks; + #[path = "../unsupported/once.rs"] + pub mod once; #[path = "../unsupported/thread.rs"] pub mod thread; } diff --git a/library/std/src/sys/windows/c.rs b/library/std/src/sys/windows/c.rs index 81461de4f..f58dcf128 100644 --- a/library/std/src/sys/windows/c.rs +++ b/library/std/src/sys/windows/c.rs @@ -295,8 +295,6 @@ pub fn nt_success(status: NTSTATUS) -> bool { status >= 0 } -// "RNG\0" -pub const BCRYPT_RNG_ALGORITHM: &[u16] = &[b'R' as u16, b'N' as u16, b'G' as u16, 0]; pub const BCRYPT_USE_SYSTEM_PREFERRED_RNG: DWORD = 0x00000002; #[repr(C)] @@ -834,6 +832,10 @@ if #[cfg(not(target_vendor = "uwp"))] { #[link(name = "advapi32")] extern "system" { + // Forbidden when targeting UWP + #[link_name = "SystemFunction036"] + pub fn RtlGenRandom(RandomBuffer: *mut u8, RandomBufferLength: ULONG) -> BOOLEAN; + // Allowed but unused by UWP pub fn OpenProcessToken( ProcessHandle: HANDLE, @@ -1258,13 +1260,6 @@ extern "system" { cbBuffer: ULONG, dwFlags: ULONG, ) -> NTSTATUS; - pub fn BCryptOpenAlgorithmProvider( - phalgorithm: *mut BCRYPT_ALG_HANDLE, - pszAlgId: LPCWSTR, - pszimplementation: LPCWSTR, - dwflags: ULONG, - ) -> NTSTATUS; - pub fn BCryptCloseAlgorithmProvider(hAlgorithm: BCRYPT_ALG_HANDLE, dwFlags: ULONG) -> NTSTATUS; } // Functions that aren't available on every version of Windows that we support, diff --git a/library/std/src/sys/windows/mod.rs b/library/std/src/sys/windows/mod.rs index e67411e16..77359abe4 100644 --- a/library/std/src/sys/windows/mod.rs +++ b/library/std/src/sys/windows/mod.rs @@ -33,7 +33,7 @@ pub mod stdio; pub mod thread; pub mod thread_local_dtor; pub mod thread_local_key; -pub mod thread_parker; +pub mod thread_parking; pub mod time; cfg_if::cfg_if! { if #[cfg(not(target_vendor = "uwp"))] { diff --git a/library/std/src/sys/windows/os.rs b/library/std/src/sys/windows/os.rs index 352337ba3..d7adeb266 100644 --- a/library/std/src/sys/windows/os.rs +++ b/library/std/src/sys/windows/os.rs @@ -157,7 +157,7 @@ impl<'a> Iterator for SplitPaths<'a> { // Double quotes are used as a way of introducing literal semicolons // (since c:\some;dir is a valid Windows path). Double quotes are not // themselves permitted in path names, so there is no way to escape a - // double quote. Quoted regions can appear in arbitrary locations, so + // double quote. Quoted regions can appear in arbitrary locations, so // // c:\foo;c:\som"e;di"r;c:\bar // diff --git a/library/std/src/sys/windows/pipe.rs b/library/std/src/sys/windows/pipe.rs index 9f26acc45..7b25edaa5 100644 --- a/library/std/src/sys/windows/pipe.rs +++ b/library/std/src/sys/windows/pipe.rs @@ -1,7 +1,7 @@ use crate::os::windows::prelude::*; use crate::ffi::OsStr; -use crate::io::{self, IoSlice, IoSliceMut}; +use crate::io::{self, IoSlice, IoSliceMut, Read}; use crate::mem; use crate::path::Path; use crate::ptr; @@ -261,6 +261,10 @@ impl AnonPipe { self.inner.is_read_vectored() } + pub fn read_to_end(&self, buf: &mut Vec<u8>) -> io::Result<usize> { + self.handle().read_to_end(buf) + } + pub fn write(&self, buf: &[u8]) -> io::Result<usize> { unsafe { let len = crate::cmp::min(buf.len(), c::DWORD::MAX as usize) as c::DWORD; diff --git a/library/std/src/sys/windows/process.rs b/library/std/src/sys/windows/process.rs index 31e9b34fb..10bc949e1 100644 --- a/library/std/src/sys/windows/process.rs +++ b/library/std/src/sys/windows/process.rs @@ -351,6 +351,11 @@ impl Command { )) } } + + pub fn output(&mut self) -> io::Result<(ExitStatus, Vec<u8>, Vec<u8>)> { + let (proc, pipes) = self.spawn(Stdio::MakePipe, false)?; + crate::sys_common::process::wait_with_output(proc, pipes) + } } impl fmt::Debug for Command { diff --git a/library/std/src/sys/windows/rand.rs b/library/std/src/sys/windows/rand.rs index b5a49489d..cdf37cfe9 100644 --- a/library/std/src/sys/windows/rand.rs +++ b/library/std/src/sys/windows/rand.rs @@ -1,106 +1,39 @@ -//! # Random key generation -//! -//! This module wraps the RNG provided by the OS. There are a few different -//! ways to interface with the OS RNG so it's worth exploring each of the options. -//! Note that at the time of writing these all go through the (undocumented) -//! `bcryptPrimitives.dll` but they use different route to get there. -//! -//! Originally we were using [`RtlGenRandom`], however that function is -//! deprecated and warns it "may be altered or unavailable in subsequent versions". -//! -//! So we switched to [`BCryptGenRandom`] with the `BCRYPT_USE_SYSTEM_PREFERRED_RNG` -//! flag to query and find the system configured RNG. However, this change caused a small -//! but significant number of users to experience panics caused by a failure of -//! this function. See [#94098]. -//! -//! The current version falls back to using `BCryptOpenAlgorithmProvider` if -//! `BCRYPT_USE_SYSTEM_PREFERRED_RNG` fails for any reason. -//! -//! [#94098]: https://github.com/rust-lang/rust/issues/94098 -//! [`RtlGenRandom`]: https://docs.microsoft.com/en-us/windows/win32/api/ntsecapi/nf-ntsecapi-rtlgenrandom -//! [`BCryptGenRandom`]: https://docs.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom +use crate::io; use crate::mem; use crate::ptr; use crate::sys::c; -/// Generates high quality secure random keys for use by [`HashMap`]. -/// -/// This is used to seed the default [`RandomState`]. -/// -/// [`HashMap`]: crate::collections::HashMap -/// [`RandomState`]: crate::collections::hash_map::RandomState pub fn hashmap_random_keys() -> (u64, u64) { - Rng::SYSTEM.gen_random_keys().unwrap_or_else(fallback_rng) + let mut v = (0, 0); + let ret = unsafe { + c::BCryptGenRandom( + ptr::null_mut(), + &mut v as *mut _ as *mut u8, + mem::size_of_val(&v) as c::ULONG, + c::BCRYPT_USE_SYSTEM_PREFERRED_RNG, + ) + }; + if c::nt_success(ret) { v } else { fallback_rng() } } -struct Rng { - algorithm: c::BCRYPT_ALG_HANDLE, - flags: u32, -} -impl Rng { - const SYSTEM: Self = unsafe { Self::new(ptr::null_mut(), c::BCRYPT_USE_SYSTEM_PREFERRED_RNG) }; - - /// Create the RNG from an existing algorithm handle. - /// - /// # Safety - /// - /// The handle must either be null or a valid algorithm handle. - const unsafe fn new(algorithm: c::BCRYPT_ALG_HANDLE, flags: u32) -> Self { - Self { algorithm, flags } - } - - /// Open a handle to the RNG algorithm. - fn open() -> Result<Self, c::NTSTATUS> { - use crate::sync::atomic::AtomicPtr; - use crate::sync::atomic::Ordering::{Acquire, Release}; - - // An atomic is used so we don't need to reopen the handle every time. - static HANDLE: AtomicPtr<crate::ffi::c_void> = AtomicPtr::new(ptr::null_mut()); - - let mut handle = HANDLE.load(Acquire); - if handle.is_null() { - let status = unsafe { - c::BCryptOpenAlgorithmProvider( - &mut handle, - c::BCRYPT_RNG_ALGORITHM.as_ptr(), - ptr::null(), - 0, - ) - }; - if c::nt_success(status) { - // If another thread opens a handle first then use that handle instead. - let result = HANDLE.compare_exchange(ptr::null_mut(), handle, Release, Acquire); - if let Err(previous_handle) = result { - // Close our handle and return the previous one. - unsafe { c::BCryptCloseAlgorithmProvider(handle, 0) }; - handle = previous_handle; - } - Ok(unsafe { Self::new(handle, 0) }) - } else { - Err(status) - } - } else { - Ok(unsafe { Self::new(handle, 0) }) - } - } +/// Generate random numbers using the fallback RNG function (RtlGenRandom) +/// +/// This is necessary because of a failure to load the SysWOW64 variant of the +/// bcryptprimitives.dll library from code that lives in bcrypt.dll +/// See <https://bugzilla.mozilla.org/show_bug.cgi?id=1788004#c9> +#[cfg(not(target_vendor = "uwp"))] +#[inline(never)] +fn fallback_rng() -> (u64, u64) { + let mut v = (0, 0); + let ret = + unsafe { c::RtlGenRandom(&mut v as *mut _ as *mut u8, mem::size_of_val(&v) as c::ULONG) }; - fn gen_random_keys(self) -> Result<(u64, u64), c::NTSTATUS> { - let mut v = (0, 0); - let status = unsafe { - let size = mem::size_of_val(&v).try_into().unwrap(); - c::BCryptGenRandom(self.algorithm, ptr::addr_of_mut!(v).cast(), size, self.flags) - }; - if c::nt_success(status) { Ok(v) } else { Err(status) } - } + if ret != 0 { v } else { panic!("fallback RNG broken: {}", io::Error::last_os_error()) } } -/// Generate random numbers using the fallback RNG function +/// We can't use RtlGenRandom with UWP, so there is no fallback +#[cfg(target_vendor = "uwp")] #[inline(never)] -fn fallback_rng(rng_status: c::NTSTATUS) -> (u64, u64) { - match Rng::open().and_then(|rng| rng.gen_random_keys()) { - Ok(keys) => keys, - Err(status) => { - panic!("RNG broken: {rng_status:#x}, fallback RNG broken: {status:#x}") - } - } +fn fallback_rng() -> (u64, u64) { + panic!("fallback RNG broken: RtlGenRandom() not supported on UWP"); } diff --git a/library/std/src/sys/windows/thread.rs b/library/std/src/sys/windows/thread.rs index c5c9e97e6..1cb576c95 100644 --- a/library/std/src/sys/windows/thread.rs +++ b/library/std/src/sys/windows/thread.rs @@ -26,7 +26,7 @@ impl Thread { // FIXME On UNIX, we guard against stack sizes that are too small but // that's because pthreads enforces that stacks are at least - // PTHREAD_STACK_MIN bytes big. Windows has no such lower limit, it's + // PTHREAD_STACK_MIN bytes big. Windows has no such lower limit, it's // just that below a certain threshold you can't do anything useful. // That threshold is application and architecture-specific, however. let ret = c::CreateThread( diff --git a/library/std/src/sys/windows/thread_parker.rs b/library/std/src/sys/windows/thread_parker.rs deleted file mode 100644 index 2f7ae863b..000000000 --- a/library/std/src/sys/windows/thread_parker.rs +++ /dev/null @@ -1,253 +0,0 @@ -// Thread parker implementation for Windows. -// -// This uses WaitOnAddress and WakeByAddressSingle if available (Windows 8+). -// This modern API is exactly the same as the futex syscalls the Linux thread -// parker uses. When These APIs are available, the implementation of this -// thread parker matches the Linux thread parker exactly. -// -// However, when the modern API is not available, this implementation falls -// back to NT Keyed Events, which are similar, but have some important -// differences. These are available since Windows XP. -// -// WaitOnAddress first checks the state of the thread parker to make sure it no -// WakeByAddressSingle calls can be missed between updating the parker state -// and calling the function. -// -// NtWaitForKeyedEvent does not have this option, and unconditionally blocks -// without checking the parker state first. Instead, NtReleaseKeyedEvent -// (unlike WakeByAddressSingle) *blocks* until it woke up a thread waiting for -// it by NtWaitForKeyedEvent. This way, we can be sure no events are missed, -// but we need to be careful not to block unpark() if park_timeout() was woken -// up by a timeout instead of unpark(). -// -// Unlike WaitOnAddress, NtWaitForKeyedEvent/NtReleaseKeyedEvent operate on a -// HANDLE (created with NtCreateKeyedEvent). This means that we can be sure -// a successfully awoken park() was awoken by unpark() and not a -// NtReleaseKeyedEvent call from some other code, as these events are not only -// matched by the key (address of the parker (state)), but also by this HANDLE. -// We lazily allocate this handle the first time it is needed. -// -// The fast path (calling park() after unpark() was already called) and the -// possible states are the same for both implementations. This is used here to -// make sure the fast path does not even check which API to use, but can return -// right away, independent of the used API. Only the slow paths (which will -// actually block/wake a thread) check which API is available and have -// different implementations. -// -// Unfortunately, NT Keyed Events are an undocumented Windows API. However: -// - This API is relatively simple with obvious behaviour, and there are -// several (unofficial) articles documenting the details. [1] -// - `parking_lot` has been using this API for years (on Windows versions -// before Windows 8). [2] Many big projects extensively use parking_lot, -// such as servo and the Rust compiler itself. -// - It is the underlying API used by Windows SRW locks and Windows critical -// sections. [3] [4] -// - The source code of the implementations of Wine, ReactOs, and Windows XP -// are available and match the expected behaviour. -// - The main risk with an undocumented API is that it might change in the -// future. But since we only use it for older versions of Windows, that's not -// a problem. -// - Even if these functions do not block or wake as we expect (which is -// unlikely, see all previous points), this implementation would still be -// memory safe. The NT Keyed Events API is only used to sleep/block in the -// right place. -// -// [1]: http://www.locklessinc.com/articles/keyed_events/ -// [2]: https://github.com/Amanieu/parking_lot/commit/43abbc964e -// [3]: https://docs.microsoft.com/en-us/archive/msdn-magazine/2012/november/windows-with-c-the-evolution-of-synchronization-in-windows-and-c -// [4]: Windows Internals, Part 1, ISBN 9780735671300 - -use crate::pin::Pin; -use crate::ptr; -use crate::sync::atomic::{ - AtomicI8, AtomicPtr, - Ordering::{Acquire, Relaxed, Release}, -}; -use crate::sys::{c, dur2timeout}; -use crate::time::Duration; - -pub struct Parker { - state: AtomicI8, -} - -const PARKED: i8 = -1; -const EMPTY: i8 = 0; -const NOTIFIED: i8 = 1; - -// Notes about memory ordering: -// -// Memory ordering is only relevant for the relative ordering of operations -// between different variables. Even Ordering::Relaxed guarantees a -// monotonic/consistent order when looking at just a single atomic variable. -// -// So, since this parker is just a single atomic variable, we only need to look -// at the ordering guarantees we need to provide to the 'outside world'. -// -// The only memory ordering guarantee that parking and unparking provide, is -// that things which happened before unpark() are visible on the thread -// returning from park() afterwards. Otherwise, it was effectively unparked -// before unpark() was called while still consuming the 'token'. -// -// In other words, unpark() needs to synchronize with the part of park() that -// consumes the token and returns. -// -// This is done with a release-acquire synchronization, by using -// Ordering::Release when writing NOTIFIED (the 'token') in unpark(), and using -// Ordering::Acquire when reading this state in park() after waking up. -impl Parker { - /// Construct the Windows parker. The UNIX parker implementation - /// requires this to happen in-place. - pub unsafe fn new(parker: *mut Parker) { - parker.write(Self { state: AtomicI8::new(EMPTY) }); - } - - // Assumes this is only called by the thread that owns the Parker, - // which means that `self.state != PARKED`. This implementation doesn't require `Pin`, - // but other implementations do. - pub unsafe fn park(self: Pin<&Self>) { - // Change NOTIFIED=>EMPTY or EMPTY=>PARKED, and directly return in the - // first case. - if self.state.fetch_sub(1, Acquire) == NOTIFIED { - return; - } - - if let Some(wait_on_address) = c::WaitOnAddress::option() { - loop { - // Wait for something to happen, assuming it's still set to PARKED. - wait_on_address(self.ptr(), &PARKED as *const _ as c::LPVOID, 1, c::INFINITE); - // Change NOTIFIED=>EMPTY but leave PARKED alone. - if self.state.compare_exchange(NOTIFIED, EMPTY, Acquire, Acquire).is_ok() { - // Actually woken up by unpark(). - return; - } else { - // Spurious wake up. We loop to try again. - } - } - } else { - // Wait for unpark() to produce this event. - c::NtWaitForKeyedEvent(keyed_event_handle(), self.ptr(), 0, ptr::null_mut()); - // Set the state back to EMPTY (from either PARKED or NOTIFIED). - // Note that we don't just write EMPTY, but use swap() to also - // include an acquire-ordered read to synchronize with unpark()'s - // release-ordered write. - self.state.swap(EMPTY, Acquire); - } - } - - // Assumes this is only called by the thread that owns the Parker, - // which means that `self.state != PARKED`. This implementation doesn't require `Pin`, - // but other implementations do. - pub unsafe fn park_timeout(self: Pin<&Self>, timeout: Duration) { - // Change NOTIFIED=>EMPTY or EMPTY=>PARKED, and directly return in the - // first case. - if self.state.fetch_sub(1, Acquire) == NOTIFIED { - return; - } - - if let Some(wait_on_address) = c::WaitOnAddress::option() { - // Wait for something to happen, assuming it's still set to PARKED. - wait_on_address(self.ptr(), &PARKED as *const _ as c::LPVOID, 1, dur2timeout(timeout)); - // Set the state back to EMPTY (from either PARKED or NOTIFIED). - // Note that we don't just write EMPTY, but use swap() to also - // include an acquire-ordered read to synchronize with unpark()'s - // release-ordered write. - if self.state.swap(EMPTY, Acquire) == NOTIFIED { - // Actually woken up by unpark(). - } else { - // Timeout or spurious wake up. - // We return either way, because we can't easily tell if it was the - // timeout or not. - } - } else { - // Need to wait for unpark() using NtWaitForKeyedEvent. - let handle = keyed_event_handle(); - - // NtWaitForKeyedEvent uses a unit of 100ns, and uses negative - // values to indicate a relative time on the monotonic clock. - // This is documented here for the underlying KeWaitForSingleObject function: - // https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/wdm/nf-wdm-kewaitforsingleobject - let mut timeout = match i64::try_from((timeout.as_nanos() + 99) / 100) { - Ok(t) => -t, - Err(_) => i64::MIN, - }; - - // Wait for unpark() to produce this event. - let unparked = - c::NtWaitForKeyedEvent(handle, self.ptr(), 0, &mut timeout) == c::STATUS_SUCCESS; - - // Set the state back to EMPTY (from either PARKED or NOTIFIED). - let prev_state = self.state.swap(EMPTY, Acquire); - - if !unparked && prev_state == NOTIFIED { - // We were awoken by a timeout, not by unpark(), but the state - // was set to NOTIFIED, which means we *just* missed an - // unpark(), which is now blocked on us to wait for it. - // Wait for it to consume the event and unblock that thread. - c::NtWaitForKeyedEvent(handle, self.ptr(), 0, ptr::null_mut()); - } - } - } - - // This implementation doesn't require `Pin`, but other implementations do. - pub fn unpark(self: Pin<&Self>) { - // Change PARKED=>NOTIFIED, EMPTY=>NOTIFIED, or NOTIFIED=>NOTIFIED, and - // wake the thread in the first case. - // - // Note that even NOTIFIED=>NOTIFIED results in a write. This is on - // purpose, to make sure every unpark() has a release-acquire ordering - // with park(). - if self.state.swap(NOTIFIED, Release) == PARKED { - unsafe { - if let Some(wake_by_address_single) = c::WakeByAddressSingle::option() { - wake_by_address_single(self.ptr()); - } else { - // If we run NtReleaseKeyedEvent before the waiting thread runs - // NtWaitForKeyedEvent, this (shortly) blocks until we can wake it up. - // If the waiting thread wakes up before we run NtReleaseKeyedEvent - // (e.g. due to a timeout), this blocks until we do wake up a thread. - // To prevent this thread from blocking indefinitely in that case, - // park_impl() will, after seeing the state set to NOTIFIED after - // waking up, call NtWaitForKeyedEvent again to unblock us. - c::NtReleaseKeyedEvent(keyed_event_handle(), self.ptr(), 0, ptr::null_mut()); - } - } - } - } - - fn ptr(&self) -> c::LPVOID { - &self.state as *const _ as c::LPVOID - } -} - -fn keyed_event_handle() -> c::HANDLE { - const INVALID: c::HANDLE = ptr::invalid_mut(!0); - static HANDLE: AtomicPtr<libc::c_void> = AtomicPtr::new(INVALID); - match HANDLE.load(Relaxed) { - INVALID => { - let mut handle = c::INVALID_HANDLE_VALUE; - unsafe { - match c::NtCreateKeyedEvent( - &mut handle, - c::GENERIC_READ | c::GENERIC_WRITE, - ptr::null_mut(), - 0, - ) { - c::STATUS_SUCCESS => {} - r => panic!("Unable to create keyed event handle: error {r}"), - } - } - match HANDLE.compare_exchange(INVALID, handle, Relaxed, Relaxed) { - Ok(_) => handle, - Err(h) => { - // Lost the race to another thread initializing HANDLE before we did. - // Closing our handle and using theirs instead. - unsafe { - c::CloseHandle(handle); - } - h - } - } - } - handle => handle, - } -} diff --git a/library/std/src/sys/windows/thread_parking.rs b/library/std/src/sys/windows/thread_parking.rs new file mode 100644 index 000000000..5d43676ad --- /dev/null +++ b/library/std/src/sys/windows/thread_parking.rs @@ -0,0 +1,253 @@ +// Thread parker implementation for Windows. +// +// This uses WaitOnAddress and WakeByAddressSingle if available (Windows 8+). +// This modern API is exactly the same as the futex syscalls the Linux thread +// parker uses. When These APIs are available, the implementation of this +// thread parker matches the Linux thread parker exactly. +// +// However, when the modern API is not available, this implementation falls +// back to NT Keyed Events, which are similar, but have some important +// differences. These are available since Windows XP. +// +// WaitOnAddress first checks the state of the thread parker to make sure it no +// WakeByAddressSingle calls can be missed between updating the parker state +// and calling the function. +// +// NtWaitForKeyedEvent does not have this option, and unconditionally blocks +// without checking the parker state first. Instead, NtReleaseKeyedEvent +// (unlike WakeByAddressSingle) *blocks* until it woke up a thread waiting for +// it by NtWaitForKeyedEvent. This way, we can be sure no events are missed, +// but we need to be careful not to block unpark() if park_timeout() was woken +// up by a timeout instead of unpark(). +// +// Unlike WaitOnAddress, NtWaitForKeyedEvent/NtReleaseKeyedEvent operate on a +// HANDLE (created with NtCreateKeyedEvent). This means that we can be sure +// a successfully awoken park() was awoken by unpark() and not a +// NtReleaseKeyedEvent call from some other code, as these events are not only +// matched by the key (address of the parker (state)), but also by this HANDLE. +// We lazily allocate this handle the first time it is needed. +// +// The fast path (calling park() after unpark() was already called) and the +// possible states are the same for both implementations. This is used here to +// make sure the fast path does not even check which API to use, but can return +// right away, independent of the used API. Only the slow paths (which will +// actually block/wake a thread) check which API is available and have +// different implementations. +// +// Unfortunately, NT Keyed Events are an undocumented Windows API. However: +// - This API is relatively simple with obvious behaviour, and there are +// several (unofficial) articles documenting the details. [1] +// - `parking_lot` has been using this API for years (on Windows versions +// before Windows 8). [2] Many big projects extensively use parking_lot, +// such as servo and the Rust compiler itself. +// - It is the underlying API used by Windows SRW locks and Windows critical +// sections. [3] [4] +// - The source code of the implementations of Wine, ReactOs, and Windows XP +// are available and match the expected behaviour. +// - The main risk with an undocumented API is that it might change in the +// future. But since we only use it for older versions of Windows, that's not +// a problem. +// - Even if these functions do not block or wake as we expect (which is +// unlikely, see all previous points), this implementation would still be +// memory safe. The NT Keyed Events API is only used to sleep/block in the +// right place. +// +// [1]: http://www.locklessinc.com/articles/keyed_events/ +// [2]: https://github.com/Amanieu/parking_lot/commit/43abbc964e +// [3]: https://docs.microsoft.com/en-us/archive/msdn-magazine/2012/november/windows-with-c-the-evolution-of-synchronization-in-windows-and-c +// [4]: Windows Internals, Part 1, ISBN 9780735671300 + +use crate::pin::Pin; +use crate::ptr; +use crate::sync::atomic::{ + AtomicI8, AtomicPtr, + Ordering::{Acquire, Relaxed, Release}, +}; +use crate::sys::{c, dur2timeout}; +use crate::time::Duration; + +pub struct Parker { + state: AtomicI8, +} + +const PARKED: i8 = -1; +const EMPTY: i8 = 0; +const NOTIFIED: i8 = 1; + +// Notes about memory ordering: +// +// Memory ordering is only relevant for the relative ordering of operations +// between different variables. Even Ordering::Relaxed guarantees a +// monotonic/consistent order when looking at just a single atomic variable. +// +// So, since this parker is just a single atomic variable, we only need to look +// at the ordering guarantees we need to provide to the 'outside world'. +// +// The only memory ordering guarantee that parking and unparking provide, is +// that things which happened before unpark() are visible on the thread +// returning from park() afterwards. Otherwise, it was effectively unparked +// before unpark() was called while still consuming the 'token'. +// +// In other words, unpark() needs to synchronize with the part of park() that +// consumes the token and returns. +// +// This is done with a release-acquire synchronization, by using +// Ordering::Release when writing NOTIFIED (the 'token') in unpark(), and using +// Ordering::Acquire when reading this state in park() after waking up. +impl Parker { + /// Construct the Windows parker. The UNIX parker implementation + /// requires this to happen in-place. + pub unsafe fn new_in_place(parker: *mut Parker) { + parker.write(Self { state: AtomicI8::new(EMPTY) }); + } + + // Assumes this is only called by the thread that owns the Parker, + // which means that `self.state != PARKED`. This implementation doesn't require `Pin`, + // but other implementations do. + pub unsafe fn park(self: Pin<&Self>) { + // Change NOTIFIED=>EMPTY or EMPTY=>PARKED, and directly return in the + // first case. + if self.state.fetch_sub(1, Acquire) == NOTIFIED { + return; + } + + if let Some(wait_on_address) = c::WaitOnAddress::option() { + loop { + // Wait for something to happen, assuming it's still set to PARKED. + wait_on_address(self.ptr(), &PARKED as *const _ as c::LPVOID, 1, c::INFINITE); + // Change NOTIFIED=>EMPTY but leave PARKED alone. + if self.state.compare_exchange(NOTIFIED, EMPTY, Acquire, Acquire).is_ok() { + // Actually woken up by unpark(). + return; + } else { + // Spurious wake up. We loop to try again. + } + } + } else { + // Wait for unpark() to produce this event. + c::NtWaitForKeyedEvent(keyed_event_handle(), self.ptr(), 0, ptr::null_mut()); + // Set the state back to EMPTY (from either PARKED or NOTIFIED). + // Note that we don't just write EMPTY, but use swap() to also + // include an acquire-ordered read to synchronize with unpark()'s + // release-ordered write. + self.state.swap(EMPTY, Acquire); + } + } + + // Assumes this is only called by the thread that owns the Parker, + // which means that `self.state != PARKED`. This implementation doesn't require `Pin`, + // but other implementations do. + pub unsafe fn park_timeout(self: Pin<&Self>, timeout: Duration) { + // Change NOTIFIED=>EMPTY or EMPTY=>PARKED, and directly return in the + // first case. + if self.state.fetch_sub(1, Acquire) == NOTIFIED { + return; + } + + if let Some(wait_on_address) = c::WaitOnAddress::option() { + // Wait for something to happen, assuming it's still set to PARKED. + wait_on_address(self.ptr(), &PARKED as *const _ as c::LPVOID, 1, dur2timeout(timeout)); + // Set the state back to EMPTY (from either PARKED or NOTIFIED). + // Note that we don't just write EMPTY, but use swap() to also + // include an acquire-ordered read to synchronize with unpark()'s + // release-ordered write. + if self.state.swap(EMPTY, Acquire) == NOTIFIED { + // Actually woken up by unpark(). + } else { + // Timeout or spurious wake up. + // We return either way, because we can't easily tell if it was the + // timeout or not. + } + } else { + // Need to wait for unpark() using NtWaitForKeyedEvent. + let handle = keyed_event_handle(); + + // NtWaitForKeyedEvent uses a unit of 100ns, and uses negative + // values to indicate a relative time on the monotonic clock. + // This is documented here for the underlying KeWaitForSingleObject function: + // https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/wdm/nf-wdm-kewaitforsingleobject + let mut timeout = match i64::try_from((timeout.as_nanos() + 99) / 100) { + Ok(t) => -t, + Err(_) => i64::MIN, + }; + + // Wait for unpark() to produce this event. + let unparked = + c::NtWaitForKeyedEvent(handle, self.ptr(), 0, &mut timeout) == c::STATUS_SUCCESS; + + // Set the state back to EMPTY (from either PARKED or NOTIFIED). + let prev_state = self.state.swap(EMPTY, Acquire); + + if !unparked && prev_state == NOTIFIED { + // We were awoken by a timeout, not by unpark(), but the state + // was set to NOTIFIED, which means we *just* missed an + // unpark(), which is now blocked on us to wait for it. + // Wait for it to consume the event and unblock that thread. + c::NtWaitForKeyedEvent(handle, self.ptr(), 0, ptr::null_mut()); + } + } + } + + // This implementation doesn't require `Pin`, but other implementations do. + pub fn unpark(self: Pin<&Self>) { + // Change PARKED=>NOTIFIED, EMPTY=>NOTIFIED, or NOTIFIED=>NOTIFIED, and + // wake the thread in the first case. + // + // Note that even NOTIFIED=>NOTIFIED results in a write. This is on + // purpose, to make sure every unpark() has a release-acquire ordering + // with park(). + if self.state.swap(NOTIFIED, Release) == PARKED { + unsafe { + if let Some(wake_by_address_single) = c::WakeByAddressSingle::option() { + wake_by_address_single(self.ptr()); + } else { + // If we run NtReleaseKeyedEvent before the waiting thread runs + // NtWaitForKeyedEvent, this (shortly) blocks until we can wake it up. + // If the waiting thread wakes up before we run NtReleaseKeyedEvent + // (e.g. due to a timeout), this blocks until we do wake up a thread. + // To prevent this thread from blocking indefinitely in that case, + // park_impl() will, after seeing the state set to NOTIFIED after + // waking up, call NtWaitForKeyedEvent again to unblock us. + c::NtReleaseKeyedEvent(keyed_event_handle(), self.ptr(), 0, ptr::null_mut()); + } + } + } + } + + fn ptr(&self) -> c::LPVOID { + &self.state as *const _ as c::LPVOID + } +} + +fn keyed_event_handle() -> c::HANDLE { + const INVALID: c::HANDLE = ptr::invalid_mut(!0); + static HANDLE: AtomicPtr<libc::c_void> = AtomicPtr::new(INVALID); + match HANDLE.load(Relaxed) { + INVALID => { + let mut handle = c::INVALID_HANDLE_VALUE; + unsafe { + match c::NtCreateKeyedEvent( + &mut handle, + c::GENERIC_READ | c::GENERIC_WRITE, + ptr::null_mut(), + 0, + ) { + c::STATUS_SUCCESS => {} + r => panic!("Unable to create keyed event handle: error {r}"), + } + } + match HANDLE.compare_exchange(INVALID, handle, Relaxed, Relaxed) { + Ok(_) => handle, + Err(h) => { + // Lost the race to another thread initializing HANDLE before we did. + // Closing our handle and using theirs instead. + unsafe { + c::CloseHandle(handle); + } + h + } + } + } + handle => handle, + } +} diff --git a/library/std/src/sys_common/backtrace.rs b/library/std/src/sys_common/backtrace.rs index 8807077cb..f1d804ef4 100644 --- a/library/std/src/sys_common/backtrace.rs +++ b/library/std/src/sys_common/backtrace.rs @@ -20,7 +20,7 @@ pub fn lock() -> impl Drop { /// Prints the current backtrace. pub fn print(w: &mut dyn Write, format: PrintFmt) -> io::Result<()> { // There are issues currently linking libbacktrace into tests, and in - // general during libstd's own unit tests we're not testing this path. In + // general during std's own unit tests we're not testing this path. In // test mode immediately return here to optimize away any references to the // libbacktrace symbols if cfg!(test) { @@ -111,7 +111,7 @@ unsafe fn _print_fmt(fmt: &mut fmt::Formatter<'_>, print_fmt: PrintFmt) -> fmt:: } /// Fixed frame used to clean the backtrace with `RUST_BACKTRACE=1`. Note that -/// this is only inline(never) when backtraces in libstd are enabled, otherwise +/// this is only inline(never) when backtraces in std are enabled, otherwise /// it's fine to optimize away. #[cfg_attr(feature = "backtrace", inline(never))] pub fn __rust_begin_short_backtrace<F, T>(f: F) -> T @@ -127,7 +127,7 @@ where } /// Fixed frame used to clean the backtrace with `RUST_BACKTRACE=1`. Note that -/// this is only inline(never) when backtraces in libstd are enabled, otherwise +/// this is only inline(never) when backtraces in std are enabled, otherwise /// it's fine to optimize away. #[cfg_attr(feature = "backtrace", inline(never))] pub fn __rust_end_short_backtrace<F, T>(f: F) -> T diff --git a/library/std/src/sys_common/io.rs b/library/std/src/sys_common/io.rs index d1e9fed41..4a42ff3c6 100644 --- a/library/std/src/sys_common/io.rs +++ b/library/std/src/sys_common/io.rs @@ -39,9 +39,10 @@ pub mod test { } } + #[track_caller] // for `test_rng` pub fn tmpdir() -> TempDir { let p = env::temp_dir(); - let mut r = rand::thread_rng(); + let mut r = crate::test_helpers::test_rng(); let ret = p.join(&format!("rust-{}", r.next_u32())); fs::create_dir(&ret).unwrap(); TempDir(ret) diff --git a/library/std/src/sys_common/mod.rs b/library/std/src/sys_common/mod.rs index b1987aa0f..6b24b0e9a 100644 --- a/library/std/src/sys_common/mod.rs +++ b/library/std/src/sys_common/mod.rs @@ -27,11 +27,10 @@ pub mod lazy_box; pub mod memchr; pub mod once; pub mod process; -pub mod remutex; pub mod thread; pub mod thread_info; pub mod thread_local_dtor; -pub mod thread_parker; +pub mod thread_parking; pub mod wstr; pub mod wtf8; diff --git a/library/std/src/sys_common/once/mod.rs b/library/std/src/sys_common/once/mod.rs index 8742e68cc..359697d83 100644 --- a/library/std/src/sys_common/once/mod.rs +++ b/library/std/src/sys_common/once/mod.rs @@ -6,22 +6,6 @@ // As a result, we end up implementing it ourselves in the standard library. // This also gives us the opportunity to optimize the implementation a bit which // should help the fast path on call sites. -// -// So to recap, the guarantees of a Once are that it will call the -// initialization closure at most once, and it will never return until the one -// that's running has finished running. This means that we need some form of -// blocking here while the custom callback is running at the very least. -// Additionally, we add on the restriction of **poisoning**. Whenever an -// initialization closure panics, the Once enters a "poisoned" state which means -// that all future calls will immediately panic as well. -// -// So to implement this, one might first reach for a `Mutex`, but those cannot -// be put into a `static`. It also gets a lot harder with poisoning to figure -// out when the mutex needs to be deallocated because it's not after the closure -// finishes, but after the first successful closure finishes. -// -// All in all, this is instead implemented with atomics and lock-free -// operations! Whee! cfg_if::cfg_if! { if #[cfg(any( @@ -36,8 +20,15 @@ cfg_if::cfg_if! { ))] { mod futex; pub use futex::{Once, OnceState}; + } else if #[cfg(any( + windows, + target_family = "unix", + all(target_vendor = "fortanix", target_env = "sgx"), + target_os = "solid_asp3", + ))] { + mod queue; + pub use queue::{Once, OnceState}; } else { - mod generic; - pub use generic::{Once, OnceState}; + pub use crate::sys::once::{Once, OnceState}; } } diff --git a/library/std/src/sys_common/once/generic.rs b/library/std/src/sys_common/once/queue.rs index d953a6745..d953a6745 100644 --- a/library/std/src/sys_common/once/generic.rs +++ b/library/std/src/sys_common/once/queue.rs diff --git a/library/std/src/sys_common/process.rs b/library/std/src/sys_common/process.rs index 9f978789a..18883048d 100644 --- a/library/std/src/sys_common/process.rs +++ b/library/std/src/sys_common/process.rs @@ -4,10 +4,13 @@ use crate::collections::BTreeMap; use crate::env; use crate::ffi::{OsStr, OsString}; -use crate::sys::process::EnvKey; +use crate::fmt; +use crate::io; +use crate::sys::pipe::read2; +use crate::sys::process::{EnvKey, ExitStatus, Process, StdioPipes}; // Stores a set of changes to an environment -#[derive(Clone, Debug)] +#[derive(Clone)] pub struct CommandEnv { clear: bool, saw_path: bool, @@ -20,6 +23,14 @@ impl Default for CommandEnv { } } +impl fmt::Debug for CommandEnv { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + let mut debug_command_env = f.debug_struct("CommandEnv"); + debug_command_env.field("clear", &self.clear).field("vars", &self.vars); + debug_command_env.finish() + } +} + impl CommandEnv { // Capture the current environment with these changes applied pub fn capture(&self) -> BTreeMap<EnvKey, OsString> { @@ -117,3 +128,30 @@ impl<'a> ExactSizeIterator for CommandEnvs<'a> { self.iter.is_empty() } } + +pub fn wait_with_output( + mut process: Process, + mut pipes: StdioPipes, +) -> io::Result<(ExitStatus, Vec<u8>, Vec<u8>)> { + drop(pipes.stdin.take()); + + let (mut stdout, mut stderr) = (Vec::new(), Vec::new()); + match (pipes.stdout.take(), pipes.stderr.take()) { + (None, None) => {} + (Some(out), None) => { + let res = out.read_to_end(&mut stdout); + res.unwrap(); + } + (None, Some(err)) => { + let res = err.read_to_end(&mut stderr); + res.unwrap(); + } + (Some(out), Some(err)) => { + let res = read2(out, &mut stdout, err, &mut stderr); + res.unwrap(); + } + } + + let status = process.wait()?; + Ok((status, stdout, stderr)) +} diff --git a/library/std/src/sys_common/remutex/tests.rs b/library/std/src/sys_common/remutex/tests.rs deleted file mode 100644 index 8e97ce11c..000000000 --- a/library/std/src/sys_common/remutex/tests.rs +++ /dev/null @@ -1,60 +0,0 @@ -use crate::cell::RefCell; -use crate::sync::Arc; -use crate::sys_common::remutex::{ReentrantMutex, ReentrantMutexGuard}; -use crate::thread; - -#[test] -fn smoke() { - let m = ReentrantMutex::new(()); - { - let a = m.lock(); - { - let b = m.lock(); - { - let c = m.lock(); - assert_eq!(*c, ()); - } - assert_eq!(*b, ()); - } - assert_eq!(*a, ()); - } -} - -#[test] -fn is_mutex() { - let m = Arc::new(ReentrantMutex::new(RefCell::new(0))); - let m2 = m.clone(); - let lock = m.lock(); - let child = thread::spawn(move || { - let lock = m2.lock(); - assert_eq!(*lock.borrow(), 4950); - }); - for i in 0..100 { - let lock = m.lock(); - *lock.borrow_mut() += i; - } - drop(lock); - child.join().unwrap(); -} - -#[test] -fn trylock_works() { - let m = Arc::new(ReentrantMutex::new(())); - let m2 = m.clone(); - let _lock = m.try_lock(); - let _lock2 = m.try_lock(); - thread::spawn(move || { - let lock = m2.try_lock(); - assert!(lock.is_none()); - }) - .join() - .unwrap(); - let _lock3 = m.try_lock(); -} - -pub struct Answer<'a>(pub ReentrantMutexGuard<'a, RefCell<u32>>); -impl Drop for Answer<'_> { - fn drop(&mut self) { - *self.0.borrow_mut() = 42; - } -} diff --git a/library/std/src/sys_common/thread_local_key.rs b/library/std/src/sys_common/thread_local_key.rs index 747579f17..2672a2a75 100644 --- a/library/std/src/sys_common/thread_local_key.rs +++ b/library/std/src/sys_common/thread_local_key.rs @@ -117,10 +117,14 @@ pub struct Key { /// This value specifies no destructor by default. pub const INIT: StaticKey = StaticKey::new(None); +// Define a sentinel value that is unlikely to be returned +// as a TLS key (but it may be returned). +const KEY_SENTVAL: usize = 0; + impl StaticKey { #[rustc_const_unstable(feature = "thread_local_internals", issue = "none")] pub const fn new(dtor: Option<unsafe extern "C" fn(*mut u8)>) -> StaticKey { - StaticKey { key: atomic::AtomicUsize::new(0), dtor } + StaticKey { key: atomic::AtomicUsize::new(KEY_SENTVAL), dtor } } /// Gets the value associated with this TLS key @@ -144,31 +148,36 @@ impl StaticKey { #[inline] unsafe fn key(&self) -> imp::Key { match self.key.load(Ordering::Relaxed) { - 0 => self.lazy_init() as imp::Key, + KEY_SENTVAL => self.lazy_init() as imp::Key, n => n as imp::Key, } } unsafe fn lazy_init(&self) -> usize { - // POSIX allows the key created here to be 0, but the compare_exchange - // below relies on using 0 as a sentinel value to check who won the + // POSIX allows the key created here to be KEY_SENTVAL, but the compare_exchange + // below relies on using KEY_SENTVAL as a sentinel value to check who won the // race to set the shared TLS key. As far as I know, there is no // guaranteed value that cannot be returned as a posix_key_create key, // so there is no value we can initialize the inner key with to // prove that it has not yet been set. As such, we'll continue using a - // value of 0, but with some gyrations to make sure we have a non-0 + // value of KEY_SENTVAL, but with some gyrations to make sure we have a non-KEY_SENTVAL // value returned from the creation routine. // FIXME: this is clearly a hack, and should be cleaned up. let key1 = imp::create(self.dtor); - let key = if key1 != 0 { + let key = if key1 as usize != KEY_SENTVAL { key1 } else { let key2 = imp::create(self.dtor); imp::destroy(key1); key2 }; - rtassert!(key != 0); - match self.key.compare_exchange(0, key as usize, Ordering::SeqCst, Ordering::SeqCst) { + rtassert!(key as usize != KEY_SENTVAL); + match self.key.compare_exchange( + KEY_SENTVAL, + key as usize, + Ordering::SeqCst, + Ordering::SeqCst, + ) { // The CAS succeeded, so we've created the actual key Ok(_) => key as usize, // If someone beat us to the punch, use their key instead diff --git a/library/std/src/sys_common/thread_parker/generic.rs b/library/std/src/sys_common/thread_parker/generic.rs deleted file mode 100644 index f3d8b34d3..000000000 --- a/library/std/src/sys_common/thread_parker/generic.rs +++ /dev/null @@ -1,125 +0,0 @@ -//! Parker implementation based on a Mutex and Condvar. - -use crate::pin::Pin; -use crate::sync::atomic::AtomicUsize; -use crate::sync::atomic::Ordering::SeqCst; -use crate::sync::{Condvar, Mutex}; -use crate::time::Duration; - -const EMPTY: usize = 0; -const PARKED: usize = 1; -const NOTIFIED: usize = 2; - -pub struct Parker { - state: AtomicUsize, - lock: Mutex<()>, - cvar: Condvar, -} - -impl Parker { - /// Construct the generic parker. The UNIX parker implementation - /// requires this to happen in-place. - pub unsafe fn new(parker: *mut Parker) { - parker.write(Parker { - state: AtomicUsize::new(EMPTY), - lock: Mutex::new(()), - cvar: Condvar::new(), - }); - } - - // This implementation doesn't require `unsafe` and `Pin`, but other implementations do. - pub unsafe fn park(self: Pin<&Self>) { - // If we were previously notified then we consume this notification and - // return quickly. - if self.state.compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst).is_ok() { - return; - } - - // Otherwise we need to coordinate going to sleep - let mut m = self.lock.lock().unwrap(); - match self.state.compare_exchange(EMPTY, PARKED, SeqCst, SeqCst) { - Ok(_) => {} - Err(NOTIFIED) => { - // We must read here, even though we know it will be `NOTIFIED`. - // This is because `unpark` may have been called again since we read - // `NOTIFIED` in the `compare_exchange` above. We must perform an - // acquire operation that synchronizes with that `unpark` to observe - // any writes it made before the call to unpark. To do that we must - // read from the write it made to `state`. - let old = self.state.swap(EMPTY, SeqCst); - assert_eq!(old, NOTIFIED, "park state changed unexpectedly"); - return; - } // should consume this notification, so prohibit spurious wakeups in next park. - Err(_) => panic!("inconsistent park state"), - } - loop { - m = self.cvar.wait(m).unwrap(); - match self.state.compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst) { - Ok(_) => return, // got a notification - Err(_) => {} // spurious wakeup, go back to sleep - } - } - } - - // This implementation doesn't require `unsafe` and `Pin`, but other implementations do. - pub unsafe fn park_timeout(self: Pin<&Self>, dur: Duration) { - // Like `park` above we have a fast path for an already-notified thread, and - // afterwards we start coordinating for a sleep. - // return quickly. - if self.state.compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst).is_ok() { - return; - } - let m = self.lock.lock().unwrap(); - match self.state.compare_exchange(EMPTY, PARKED, SeqCst, SeqCst) { - Ok(_) => {} - Err(NOTIFIED) => { - // We must read again here, see `park`. - let old = self.state.swap(EMPTY, SeqCst); - assert_eq!(old, NOTIFIED, "park state changed unexpectedly"); - return; - } // should consume this notification, so prohibit spurious wakeups in next park. - Err(_) => panic!("inconsistent park_timeout state"), - } - - // Wait with a timeout, and if we spuriously wake up or otherwise wake up - // from a notification we just want to unconditionally set the state back to - // empty, either consuming a notification or un-flagging ourselves as - // parked. - let (_m, _result) = self.cvar.wait_timeout(m, dur).unwrap(); - match self.state.swap(EMPTY, SeqCst) { - NOTIFIED => {} // got a notification, hurray! - PARKED => {} // no notification, alas - n => panic!("inconsistent park_timeout state: {n}"), - } - } - - // This implementation doesn't require `Pin`, but other implementations do. - pub fn unpark(self: Pin<&Self>) { - // To ensure the unparked thread will observe any writes we made - // before this call, we must perform a release operation that `park` - // can synchronize with. To do that we must write `NOTIFIED` even if - // `state` is already `NOTIFIED`. That is why this must be a swap - // rather than a compare-and-swap that returns if it reads `NOTIFIED` - // on failure. - match self.state.swap(NOTIFIED, SeqCst) { - EMPTY => return, // no one was waiting - NOTIFIED => return, // already unparked - PARKED => {} // gotta go wake someone up - _ => panic!("inconsistent state in unpark"), - } - - // There is a period between when the parked thread sets `state` to - // `PARKED` (or last checked `state` in the case of a spurious wake - // up) and when it actually waits on `cvar`. If we were to notify - // during this period it would be ignored and then when the parked - // thread went to sleep it would never wake up. Fortunately, it has - // `lock` locked at this stage so we can acquire `lock` to wait until - // it is ready to receive the notification. - // - // Releasing `lock` before the call to `notify_one` means that when the - // parked thread wakes it doesn't get woken only to have to wait for us - // to release `lock`. - drop(self.lock.lock().unwrap()); - self.cvar.notify_one() - } -} diff --git a/library/std/src/sys_common/thread_parker/mod.rs b/library/std/src/sys_common/thread_parker/mod.rs deleted file mode 100644 index f86a9a555..000000000 --- a/library/std/src/sys_common/thread_parker/mod.rs +++ /dev/null @@ -1,23 +0,0 @@ -cfg_if::cfg_if! { - if #[cfg(any( - target_os = "linux", - target_os = "android", - all(target_arch = "wasm32", target_feature = "atomics"), - target_os = "freebsd", - target_os = "openbsd", - target_os = "dragonfly", - target_os = "fuchsia", - target_os = "hermit", - ))] { - mod futex; - pub use futex::Parker; - } else if #[cfg(target_os = "solid_asp3")] { - mod wait_flag; - pub use wait_flag::Parker; - } else if #[cfg(any(windows, target_family = "unix"))] { - pub use crate::sys::thread_parker::Parker; - } else { - mod generic; - pub use generic::Parker; - } -} diff --git a/library/std/src/sys_common/thread_parker/futex.rs b/library/std/src/sys_common/thread_parking/futex.rs index d9e2f39e3..588e7b278 100644 --- a/library/std/src/sys_common/thread_parker/futex.rs +++ b/library/std/src/sys_common/thread_parking/futex.rs @@ -35,7 +35,7 @@ pub struct Parker { impl Parker { /// Construct the futex parker. The UNIX parker implementation /// requires this to happen in-place. - pub unsafe fn new(parker: *mut Parker) { + pub unsafe fn new_in_place(parker: *mut Parker) { parker.write(Self { state: AtomicU32::new(EMPTY) }); } diff --git a/library/std/src/sys_common/thread_parking/generic.rs b/library/std/src/sys_common/thread_parking/generic.rs new file mode 100644 index 000000000..3209bffe3 --- /dev/null +++ b/library/std/src/sys_common/thread_parking/generic.rs @@ -0,0 +1,125 @@ +//! Parker implementation based on a Mutex and Condvar. + +use crate::pin::Pin; +use crate::sync::atomic::AtomicUsize; +use crate::sync::atomic::Ordering::SeqCst; +use crate::sync::{Condvar, Mutex}; +use crate::time::Duration; + +const EMPTY: usize = 0; +const PARKED: usize = 1; +const NOTIFIED: usize = 2; + +pub struct Parker { + state: AtomicUsize, + lock: Mutex<()>, + cvar: Condvar, +} + +impl Parker { + /// Construct the generic parker. The UNIX parker implementation + /// requires this to happen in-place. + pub unsafe fn new_in_place(parker: *mut Parker) { + parker.write(Parker { + state: AtomicUsize::new(EMPTY), + lock: Mutex::new(()), + cvar: Condvar::new(), + }); + } + + // This implementation doesn't require `unsafe` and `Pin`, but other implementations do. + pub unsafe fn park(self: Pin<&Self>) { + // If we were previously notified then we consume this notification and + // return quickly. + if self.state.compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst).is_ok() { + return; + } + + // Otherwise we need to coordinate going to sleep + let mut m = self.lock.lock().unwrap(); + match self.state.compare_exchange(EMPTY, PARKED, SeqCst, SeqCst) { + Ok(_) => {} + Err(NOTIFIED) => { + // We must read here, even though we know it will be `NOTIFIED`. + // This is because `unpark` may have been called again since we read + // `NOTIFIED` in the `compare_exchange` above. We must perform an + // acquire operation that synchronizes with that `unpark` to observe + // any writes it made before the call to unpark. To do that we must + // read from the write it made to `state`. + let old = self.state.swap(EMPTY, SeqCst); + assert_eq!(old, NOTIFIED, "park state changed unexpectedly"); + return; + } // should consume this notification, so prohibit spurious wakeups in next park. + Err(_) => panic!("inconsistent park state"), + } + loop { + m = self.cvar.wait(m).unwrap(); + match self.state.compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst) { + Ok(_) => return, // got a notification + Err(_) => {} // spurious wakeup, go back to sleep + } + } + } + + // This implementation doesn't require `unsafe` and `Pin`, but other implementations do. + pub unsafe fn park_timeout(self: Pin<&Self>, dur: Duration) { + // Like `park` above we have a fast path for an already-notified thread, and + // afterwards we start coordinating for a sleep. + // return quickly. + if self.state.compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst).is_ok() { + return; + } + let m = self.lock.lock().unwrap(); + match self.state.compare_exchange(EMPTY, PARKED, SeqCst, SeqCst) { + Ok(_) => {} + Err(NOTIFIED) => { + // We must read again here, see `park`. + let old = self.state.swap(EMPTY, SeqCst); + assert_eq!(old, NOTIFIED, "park state changed unexpectedly"); + return; + } // should consume this notification, so prohibit spurious wakeups in next park. + Err(_) => panic!("inconsistent park_timeout state"), + } + + // Wait with a timeout, and if we spuriously wake up or otherwise wake up + // from a notification we just want to unconditionally set the state back to + // empty, either consuming a notification or un-flagging ourselves as + // parked. + let (_m, _result) = self.cvar.wait_timeout(m, dur).unwrap(); + match self.state.swap(EMPTY, SeqCst) { + NOTIFIED => {} // got a notification, hurray! + PARKED => {} // no notification, alas + n => panic!("inconsistent park_timeout state: {n}"), + } + } + + // This implementation doesn't require `Pin`, but other implementations do. + pub fn unpark(self: Pin<&Self>) { + // To ensure the unparked thread will observe any writes we made + // before this call, we must perform a release operation that `park` + // can synchronize with. To do that we must write `NOTIFIED` even if + // `state` is already `NOTIFIED`. That is why this must be a swap + // rather than a compare-and-swap that returns if it reads `NOTIFIED` + // on failure. + match self.state.swap(NOTIFIED, SeqCst) { + EMPTY => return, // no one was waiting + NOTIFIED => return, // already unparked + PARKED => {} // gotta go wake someone up + _ => panic!("inconsistent state in unpark"), + } + + // There is a period between when the parked thread sets `state` to + // `PARKED` (or last checked `state` in the case of a spurious wake + // up) and when it actually waits on `cvar`. If we were to notify + // during this period it would be ignored and then when the parked + // thread went to sleep it would never wake up. Fortunately, it has + // `lock` locked at this stage so we can acquire `lock` to wait until + // it is ready to receive the notification. + // + // Releasing `lock` before the call to `notify_one` means that when the + // parked thread wakes it doesn't get woken only to have to wait for us + // to release `lock`. + drop(self.lock.lock().unwrap()); + self.cvar.notify_one() + } +} diff --git a/library/std/src/sys_common/thread_parking/id.rs b/library/std/src/sys_common/thread_parking/id.rs new file mode 100644 index 000000000..e98169597 --- /dev/null +++ b/library/std/src/sys_common/thread_parking/id.rs @@ -0,0 +1,108 @@ +//! Thread parking using thread ids. +//! +//! Some platforms (notably NetBSD) have thread parking primitives whose semantics +//! match those offered by `thread::park`, with the difference that the thread to +//! be unparked is referenced by a platform-specific thread id. Since the thread +//! parker is constructed before that id is known, an atomic state variable is used +//! to manage the park state and propagate the thread id. This also avoids platform +//! calls in the case where `unpark` is called before `park`. + +use crate::cell::UnsafeCell; +use crate::pin::Pin; +use crate::sync::atomic::{ + fence, AtomicI8, + Ordering::{Acquire, Relaxed, Release}, +}; +use crate::sys::thread_parking::{current, park, park_timeout, unpark, ThreadId}; +use crate::time::Duration; + +pub struct Parker { + state: AtomicI8, + tid: UnsafeCell<Option<ThreadId>>, +} + +const PARKED: i8 = -1; +const EMPTY: i8 = 0; +const NOTIFIED: i8 = 1; + +impl Parker { + pub fn new() -> Parker { + Parker { state: AtomicI8::new(EMPTY), tid: UnsafeCell::new(None) } + } + + /// Create a new thread parker. UNIX requires this to happen in-place. + pub unsafe fn new_in_place(parker: *mut Parker) { + parker.write(Parker::new()) + } + + /// # Safety + /// * must always be called from the same thread + /// * must be called before the state is set to PARKED + unsafe fn init_tid(&self) { + // The field is only ever written to from this thread, so we don't need + // synchronization to read it here. + if self.tid.get().read().is_none() { + // Because this point is only reached once, before the state is set + // to PARKED for the first time, the non-atomic write here can not + // conflict with reads by other threads. + self.tid.get().write(Some(current())); + // Ensure that the write can be observed by all threads reading the + // state. Synchronizes with the acquire barrier in `unpark`. + fence(Release); + } + } + + pub unsafe fn park(self: Pin<&Self>) { + self.init_tid(); + + // Changes NOTIFIED to EMPTY and EMPTY to PARKED. + let mut state = self.state.fetch_sub(1, Acquire).wrapping_sub(1); + if state == PARKED { + // Loop to guard against spurious wakeups. + while state == PARKED { + park(self.state.as_mut_ptr().addr()); + state = self.state.load(Acquire); + } + + // Since the state change has already been observed with acquire + // ordering, the state can be reset with a relaxed store instead + // of a swap. + self.state.store(EMPTY, Relaxed); + } + } + + pub unsafe fn park_timeout(self: Pin<&Self>, dur: Duration) { + self.init_tid(); + + let state = self.state.fetch_sub(1, Acquire).wrapping_sub(1); + if state == PARKED { + park_timeout(dur, self.state.as_mut_ptr().addr()); + // Swap to ensure that we observe all state changes with acquire + // ordering, even if the state has been changed after the timeout + // occured. + self.state.swap(EMPTY, Acquire); + } + } + + pub fn unpark(self: Pin<&Self>) { + let state = self.state.swap(NOTIFIED, Release); + if state == PARKED { + // Synchronize with the release fence in `init_tid` to observe the + // write to `tid`. + fence(Acquire); + // # Safety + // The thread id is initialized before the state is set to `PARKED` + // for the first time and is not written to from that point on + // (negating the need for an atomic read). + let tid = unsafe { self.tid.get().read().unwrap_unchecked() }; + // It is possible that the waiting thread woke up because of a timeout + // and terminated before this call is made. This call then returns an + // error or wakes up an unrelated thread. The platform API and + // environment does allow this, however. + unpark(tid, self.state.as_mut_ptr().addr()); + } + } +} + +unsafe impl Send for Parker {} +unsafe impl Sync for Parker {} diff --git a/library/std/src/sys_common/thread_parking/mod.rs b/library/std/src/sys_common/thread_parking/mod.rs new file mode 100644 index 000000000..0ead6633c --- /dev/null +++ b/library/std/src/sys_common/thread_parking/mod.rs @@ -0,0 +1,29 @@ +cfg_if::cfg_if! { + if #[cfg(any( + target_os = "linux", + target_os = "android", + all(target_arch = "wasm32", target_feature = "atomics"), + target_os = "freebsd", + target_os = "openbsd", + target_os = "dragonfly", + target_os = "fuchsia", + target_os = "hermit", + ))] { + mod futex; + pub use futex::Parker; + } else if #[cfg(any( + target_os = "netbsd", + all(target_vendor = "fortanix", target_env = "sgx"), + ))] { + mod id; + pub use id::Parker; + } else if #[cfg(target_os = "solid_asp3")] { + mod wait_flag; + pub use wait_flag::Parker; + } else if #[cfg(any(windows, target_family = "unix"))] { + pub use crate::sys::thread_parking::Parker; + } else { + mod generic; + pub use generic::Parker; + } +} diff --git a/library/std/src/sys_common/thread_parker/wait_flag.rs b/library/std/src/sys_common/thread_parking/wait_flag.rs index 6561c1866..d0f8899a9 100644 --- a/library/std/src/sys_common/thread_parker/wait_flag.rs +++ b/library/std/src/sys_common/thread_parking/wait_flag.rs @@ -41,7 +41,7 @@ pub struct Parker { impl Parker { /// Construct a parker for the current thread. The UNIX parker /// implementation requires this to happen in-place. - pub unsafe fn new(parker: *mut Parker) { + pub unsafe fn new_in_place(parker: *mut Parker) { parker.write(Parker { state: AtomicI8::new(EMPTY), wait_flag: WaitFlag::new() }) } |