Merging upstream version 1.72.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

38 files changed, 518 insertions, 162 deletions

diff --git a/library/std/src/sys/common/small_c_string.rs b/library/std/src/sys/common/small_c_string.rs
index 01acd5191..963d17a47 100644
--- a/library/std/src/sys/common/small_c_string.rs
+++ b/library/std/src/sys/common/small_c_string.rs
@@ -19,7 +19,7 @@ pub fn run_path_with_cstr<T, F>(path: &Path, f: F) -> io::Result<T>
 where
     F: FnOnce(&CStr) -> io::Result<T>,
 {
-    run_with_cstr(path.as_os_str().bytes(), f)
+    run_with_cstr(path.as_os_str().as_os_str_bytes(), f)
 }
 
 #[inline]
diff --git a/library/std/src/sys/common/tests.rs b/library/std/src/sys/common/tests.rs
index fb6f5d6af..0a1cbcbe8 100644
--- a/library/std/src/sys/common/tests.rs
+++ b/library/std/src/sys/common/tests.rs
@@ -8,7 +8,7 @@ use core::iter::repeat;
 fn stack_allocation_works() {
     let path = Path::new("abc");
     let result = run_path_with_cstr(path, |p| {
-        assert_eq!(p, &*CString::new(path.as_os_str().bytes()).unwrap());
+        assert_eq!(p, &*CString::new(path.as_os_str().as_os_str_bytes()).unwrap());
         Ok(42)
     });
     assert_eq!(result.unwrap(), 42);
@@ -25,7 +25,7 @@ fn heap_allocation_works() {
     let path = repeat("a").take(384).collect::<String>();
     let path = Path::new(&path);
     let result = run_path_with_cstr(path, |p| {
-        assert_eq!(p, &*CString::new(path.as_os_str().bytes()).unwrap());
+        assert_eq!(p, &*CString::new(path.as_os_str().as_os_str_bytes()).unwrap());
         Ok(42)
     });
     assert_eq!(result.unwrap(), 42);
diff --git a/library/std/src/sys/common/thread_local/fast_local.rs b/library/std/src/sys/common/thread_local/fast_local.rs
index 447044a79..bc5da1a18 100644
--- a/library/std/src/sys/common/thread_local/fast_local.rs
+++ b/library/std/src/sys/common/thread_local/fast_local.rs
@@ -33,20 +33,21 @@ pub macro thread_local_inner {
             // 1 == dtor registered, dtor not run
             // 2 == dtor registered and is running or has run
             #[thread_local]
-            static mut STATE: $crate::primitive::u8 = 0;
+            static STATE: $crate::cell::Cell<$crate::primitive::u8> = $crate::cell::Cell::new(0);
 
+            // Safety: Performs `drop_in_place(ptr as *mut $t)`, and requires
+            // all that comes with it.
             unsafe extern "C" fn destroy(ptr: *mut $crate::primitive::u8) {
-                let ptr = ptr as *mut $t;
-
-                unsafe {
-                    $crate::debug_assert_eq!(STATE, 1);
-                    STATE = 2;
-                    $crate::ptr::drop_in_place(ptr);
-                }
+                $crate::thread::local_impl::abort_on_dtor_unwind(|| {
+                    let old_state = STATE.replace(2);
+                    $crate::debug_assert_eq!(old_state, 1);
+                    // Safety: safety requirement is passed on to caller.
+                    unsafe { $crate::ptr::drop_in_place(ptr.cast::<$t>()); }
+                });
             }
 
             unsafe {
-                match STATE {
+                match STATE.get() {
                     // 0 == we haven't registered a destructor, so do
                     //   so now.
                     0 => {
@@ -54,7 +55,7 @@ pub macro thread_local_inner {
                             $crate::ptr::addr_of_mut!(VAL) as *mut $crate::primitive::u8,
                             destroy,
                         );
-                        STATE = 1;
+                        STATE.set(1);
                         $crate::option::Option::Some(&VAL)
                     }
                     // 1 == the destructor is registered and the value
@@ -148,7 +149,6 @@ impl<T> fmt::Debug for Key<T> {
         f.debug_struct("Key").finish_non_exhaustive()
     }
 }
-
 impl<T> Key<T> {
     pub const fn new() -> Key<T> {
         Key { inner: LazyKeyInner::new(), dtor_state: Cell::new(DtorState::Unregistered) }
diff --git a/library/std/src/sys/common/thread_local/mod.rs b/library/std/src/sys/common/thread_local/mod.rs
index 77f645883..975509bd4 100644
--- a/library/std/src/sys/common/thread_local/mod.rs
+++ b/library/std/src/sys/common/thread_local/mod.rs
@@ -101,3 +101,24 @@ mod lazy {
         }
     }
 }
+
+/// Run a callback in a scenario which must not unwind (such as a `extern "C"
+/// fn` declared in a user crate). If the callback unwinds anyway, then
+/// `rtabort` with a message about thread local panicking on drop.
+#[inline]
+pub fn abort_on_dtor_unwind(f: impl FnOnce()) {
+    // Using a guard like this is lower cost.
+    let guard = DtorUnwindGuard;
+    f();
+    core::mem::forget(guard);
+
+    struct DtorUnwindGuard;
+    impl Drop for DtorUnwindGuard {
+        #[inline]
+        fn drop(&mut self) {
+            // This is not terribly descriptive, but it doesn't need to be as we'll
+            // already have printed a panic message at this point.
+            rtabort!("thread local panicked on drop");
+        }
+    }
+}
diff --git a/library/std/src/sys/unix/args.rs b/library/std/src/sys/unix/args.rs
index 9ed4d9c1e..eafd6821f 100644
--- a/library/std/src/sys/unix/args.rs
+++ b/library/std/src/sys/unix/args.rs
@@ -168,7 +168,7 @@ mod imp {
     }
 }
 
-#[cfg(any(target_os = "macos", target_os = "ios", target_os = "watchos"))]
+#[cfg(any(target_os = "macos", target_os = "ios", target_os = "tvos", target_os = "watchos"))]
 mod imp {
     use super::Args;
     use crate::ffi::CStr;
@@ -209,7 +209,7 @@ mod imp {
     // for i in (0..[args count])
     //      res.push([args objectAtIndex:i])
     // res
-    #[cfg(any(target_os = "ios", target_os = "watchos"))]
+    #[cfg(any(target_os = "ios", target_os = "tvos", target_os = "watchos"))]
     pub fn args() -> Args {
         use crate::ffi::OsString;
         use crate::mem;
diff --git a/library/std/src/sys/unix/env.rs b/library/std/src/sys/unix/env.rs
index 8c3ef88d8..929e9dae7 100644
--- a/library/std/src/sys/unix/env.rs
+++ b/library/std/src/sys/unix/env.rs
@@ -31,6 +31,17 @@ pub mod os {
     pub const EXE_EXTENSION: &str = "";
 }
 
+#[cfg(target_os = "tvos")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "tvos";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".dylib";
+    pub const DLL_EXTENSION: &str = "dylib";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
 #[cfg(target_os = "watchos")]
 pub mod os {
     pub const FAMILY: &str = "unix";
diff --git a/library/std/src/sys/unix/fd.rs b/library/std/src/sys/unix/fd.rs
index cb630eede..85e020ae4 100644
--- a/library/std/src/sys/unix/fd.rs
+++ b/library/std/src/sys/unix/fd.rs
@@ -44,6 +44,7 @@ const READ_LIMIT: usize = libc::ssize_t::MAX as usize;
     target_os = "dragonfly",
     target_os = "freebsd",
     target_os = "ios",
+    target_os = "tvos",
     target_os = "macos",
     target_os = "netbsd",
     target_os = "openbsd",
@@ -69,6 +70,7 @@ const fn max_iov() -> usize {
     target_os = "emscripten",
     target_os = "freebsd",
     target_os = "ios",
+    target_os = "tvos",
     target_os = "linux",
     target_os = "macos",
     target_os = "netbsd",
@@ -181,6 +183,7 @@ impl FileDesc {
         target_os = "fuchsia",
         target_os = "illumos",
         target_os = "ios",
+        target_os = "tvos",
         target_os = "linux",
         target_os = "macos",
         target_os = "netbsd",
@@ -222,6 +225,7 @@ impl FileDesc {
     #[cfg(any(
         all(target_os = "android", target_pointer_width = "32"),
         target_os = "ios",
+        target_os = "tvos",
         target_os = "macos",
     ))]
     pub fn read_vectored_at(&self, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io::Result<usize> {
@@ -320,6 +324,7 @@ impl FileDesc {
         target_os = "fuchsia",
         target_os = "illumos",
         target_os = "ios",
+        target_os = "tvos",
         target_os = "linux",
         target_os = "macos",
         target_os = "netbsd",
@@ -361,6 +366,7 @@ impl FileDesc {
     #[cfg(any(
         all(target_os = "android", target_pointer_width = "32"),
         target_os = "ios",
+        target_os = "tvos",
         target_os = "macos",
     ))]
     pub fn write_vectored_at(&self, bufs: &[IoSlice<'_>], offset: u64) -> io::Result<usize> {
@@ -402,7 +408,10 @@ impl FileDesc {
         }
     }
     #[cfg(any(
-        all(target_env = "newlib", not(any(target_os = "espidf", target_os = "horizon"))),
+        all(
+            target_env = "newlib",
+            not(any(target_os = "espidf", target_os = "horizon", target_os = "vita"))
+        ),
         target_os = "solaris",
         target_os = "illumos",
         target_os = "emscripten",
@@ -424,10 +433,10 @@ impl FileDesc {
             Ok(())
         }
     }
-    #[cfg(any(target_os = "espidf", target_os = "horizon"))]
+    #[cfg(any(target_os = "espidf", target_os = "horizon", target_os = "vita"))]
     pub fn set_cloexec(&self) -> io::Result<()> {
-        // FD_CLOEXEC is not supported in ESP-IDF and Horizon OS but there's no need to,
-        // because neither supports spawning processes.
+        // FD_CLOEXEC is not supported in ESP-IDF, Horizon OS and Vita but there's no need to,
+        // because none of them supports spawning processes.
         Ok(())
     }
 
diff --git a/library/std/src/sys/unix/fs.rs b/library/std/src/sys/unix/fs.rs
index 09e9ae272..fbc7f04ce 100644
--- a/library/std/src/sys/unix/fs.rs
+++ b/library/std/src/sys/unix/fs.rs
@@ -15,6 +15,7 @@ use crate::mem;
     target_os = "redox",
     target_os = "illumos",
     target_os = "nto",
+    target_os = "vita",
 ))]
 use crate::mem::MaybeUninit;
 use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd};
@@ -31,6 +32,7 @@ use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
     all(target_os = "linux", target_env = "gnu"),
     target_os = "macos",
     target_os = "ios",
+    target_os = "tvos",
     target_os = "watchos",
 ))]
 use crate::sys::weak::syscall;
@@ -42,6 +44,7 @@ use libc::{c_int, mode_t};
 #[cfg(any(
     target_os = "macos",
     target_os = "ios",
+    target_os = "tvos",
     target_os = "watchos",
     target_os = "solaris",
     all(target_os = "linux", target_env = "gnu")
@@ -58,6 +61,7 @@ use libc::fstatat64;
     target_os = "redox",
     target_os = "illumos",
     target_os = "nto",
+    target_os = "vita",
 ))]
 use libc::readdir as readdir64;
 #[cfg(target_os = "linux")]
@@ -74,6 +78,7 @@ use libc::readdir64_r;
     target_os = "fuchsia",
     target_os = "redox",
     target_os = "nto",
+    target_os = "vita",
 )))]
 use libc::readdir_r as readdir64_r;
 #[cfg(target_os = "android")]
@@ -283,6 +288,7 @@ unsafe impl Sync for Dir {}
     target_os = "fuchsia",
     target_os = "redox",
     target_os = "nto",
+    target_os = "vita"
 ))]
 pub struct DirEntry {
     dir: Arc<InnerReadDir>,
@@ -304,10 +310,16 @@ pub struct DirEntry {
     target_os = "fuchsia",
     target_os = "redox",
     target_os = "nto",
+    target_os = "vita",
 ))]
 struct dirent64_min {
     d_ino: u64,
-    #[cfg(not(any(target_os = "solaris", target_os = "illumos", target_os = "nto")))]
+    #[cfg(not(any(
+        target_os = "solaris",
+        target_os = "illumos",
+        target_os = "nto",
+        target_os = "vita"
+    )))]
     d_type: u8,
 }
 
@@ -319,6 +331,7 @@ struct dirent64_min {
     target_os = "fuchsia",
     target_os = "redox",
     target_os = "nto",
+    target_os = "vita",
 )))]
 pub struct DirEntry {
     dir: Arc<InnerReadDir>,
@@ -349,7 +362,7 @@ pub struct FilePermissions {
 pub struct FileTimes {
     accessed: Option<SystemTime>,
     modified: Option<SystemTime>,
-    #[cfg(any(target_os = "macos", target_os = "ios", target_os = "watchos"))]
+    #[cfg(any(target_os = "macos", target_os = "ios", target_os = "watchos", target_os = "tvos"))]
     created: Option<SystemTime>,
 }
 
@@ -508,6 +521,7 @@ impl FileAttr {
         target_os = "openbsd",
         target_os = "macos",
         target_os = "ios",
+        target_os = "tvos",
         target_os = "watchos",
     ))]
     pub fn created(&self) -> io::Result<SystemTime> {
@@ -519,7 +533,9 @@ impl FileAttr {
         target_os = "openbsd",
         target_os = "macos",
         target_os = "ios",
+        target_os = "tvos",
         target_os = "watchos",
+        target_os = "vita",
     )))]
     pub fn created(&self) -> io::Result<SystemTime> {
         cfg_has_statx! {
@@ -541,6 +557,11 @@ impl FileAttr {
                             currently",
         ))
     }
+
+    #[cfg(target_os = "vita")]
+    pub fn created(&self) -> io::Result<SystemTime> {
+        Ok(SystemTime::new(self.stat.st_ctime as i64, 0))
+    }
 }
 
 #[cfg(target_os = "nto")]
@@ -594,7 +615,7 @@ impl FileTimes {
         self.modified = Some(t);
     }
 
-    #[cfg(any(target_os = "macos", target_os = "ios", target_os = "watchos"))]
+    #[cfg(any(target_os = "macos", target_os = "ios", target_os = "watchos", target_os = "tvos"))]
     pub fn set_created(&mut self, t: SystemTime) {
         self.created = Some(t);
     }
@@ -645,6 +666,7 @@ impl Iterator for ReadDir {
         target_os = "redox",
         target_os = "illumos",
         target_os = "nto",
+        target_os = "vita",
     ))]
     fn next(&mut self) -> Option<io::Result<DirEntry>> {
         if self.end_of_stream {
@@ -725,6 +747,7 @@ impl Iterator for ReadDir {
                     continue;
                 }
 
+                #[cfg(not(target_os = "vita"))]
                 let entry = dirent64_min {
                     d_ino: *offset_ptr!(entry_ptr, d_ino) as u64,
                     #[cfg(not(any(
@@ -735,6 +758,9 @@ impl Iterator for ReadDir {
                     d_type: *offset_ptr!(entry_ptr, d_type) as u8,
                 };
 
+                #[cfg(target_os = "vita")]
+                let entry = dirent64_min { d_ino: 0u64 };
+
                 return Some(Ok(DirEntry {
                     entry,
                     name: name.to_owned(),
@@ -752,6 +778,7 @@ impl Iterator for ReadDir {
         target_os = "redox",
         target_os = "illumos",
         target_os = "nto",
+        target_os = "vita",
     )))]
     fn next(&mut self) -> Option<io::Result<DirEntry>> {
         if self.end_of_stream {
@@ -842,6 +869,7 @@ impl DirEntry {
         target_os = "haiku",
         target_os = "vxworks",
         target_os = "nto",
+        target_os = "vita",
     ))]
     pub fn file_type(&self) -> io::Result<FileType> {
         self.metadata().map(|m| m.file_type())
@@ -853,6 +881,7 @@ impl DirEntry {
         target_os = "haiku",
         target_os = "vxworks",
         target_os = "nto",
+        target_os = "vita",
     )))]
     pub fn file_type(&self) -> io::Result<FileType> {
         match self.entry.d_type {
@@ -870,6 +899,7 @@ impl DirEntry {
     #[cfg(any(
         target_os = "macos",
         target_os = "ios",
+        target_os = "tvos",
         target_os = "watchos",
         target_os = "linux",
         target_os = "emscripten",
@@ -903,6 +933,7 @@ impl DirEntry {
     #[cfg(any(
         target_os = "macos",
         target_os = "ios",
+        target_os = "tvos",
         target_os = "watchos",
         target_os = "netbsd",
         target_os = "openbsd",
@@ -921,6 +952,7 @@ impl DirEntry {
     #[cfg(not(any(
         target_os = "macos",
         target_os = "ios",
+        target_os = "tvos",
         target_os = "watchos",
         target_os = "netbsd",
         target_os = "openbsd",
@@ -939,6 +971,7 @@ impl DirEntry {
         target_os = "fuchsia",
         target_os = "redox",
         target_os = "nto",
+        target_os = "vita",
     )))]
     fn name_cstr(&self) -> &CStr {
         unsafe { CStr::from_ptr(self.entry.d_name.as_ptr()) }
@@ -951,6 +984,7 @@ impl DirEntry {
         target_os = "fuchsia",
         target_os = "redox",
         target_os = "nto",
+        target_os = "vita",
     ))]
     fn name_cstr(&self) -> &CStr {
         &self.name
@@ -1080,11 +1114,21 @@ impl File {
         cvt_r(|| unsafe { os_fsync(self.as_raw_fd()) })?;
         return Ok(());
 
-        #[cfg(any(target_os = "macos", target_os = "ios", target_os = "watchos"))]
+        #[cfg(any(
+            target_os = "macos",
+            target_os = "ios",
+            target_os = "tvos",
+            target_os = "watchos",
+        ))]
         unsafe fn os_fsync(fd: c_int) -> c_int {
             libc::fcntl(fd, libc::F_FULLFSYNC)
         }
-        #[cfg(not(any(target_os = "macos", target_os = "ios", target_os = "watchos")))]
+        #[cfg(not(any(
+            target_os = "macos",
+            target_os = "ios",
+            target_os = "tvos",
+            target_os = "watchos",
+        )))]
         unsafe fn os_fsync(fd: c_int) -> c_int {
             libc::fsync(fd)
         }
@@ -1094,7 +1138,12 @@ impl File {
         cvt_r(|| unsafe { os_datasync(self.as_raw_fd()) })?;
         return Ok(());
 
-        #[cfg(any(target_os = "macos", target_os = "ios", target_os = "watchos"))]
+        #[cfg(any(
+            target_os = "macos",
+            target_os = "ios",
+            target_os = "tvos",
+            target_os = "watchos",
+        ))]
         unsafe fn os_datasync(fd: c_int) -> c_int {
             libc::fcntl(fd, libc::F_FULLFSYNC)
         }
@@ -1113,6 +1162,7 @@ impl File {
             target_os = "android",
             target_os = "freebsd",
             target_os = "ios",
+            target_os = "tvos",
             target_os = "linux",
             target_os = "macos",
             target_os = "netbsd",
@@ -1222,7 +1272,7 @@ impl File {
                     io::ErrorKind::Unsupported,
                     "setting file times not supported",
                 ))
-            } else if #[cfg(any(target_os = "macos", target_os = "ios", target_os = "watchos"))] {
+            } else if #[cfg(any(target_os = "macos", target_os = "ios", target_os = "tvos", target_os = "watchos"))] {
                 let mut buf = [mem::MaybeUninit::<libc::timespec>::uninit(); 3];
                 let mut num_times = 0;
                 let mut attrlist: libc::attrlist = unsafe { mem::zeroed() };
@@ -1543,7 +1593,7 @@ pub fn link(original: &Path, link: &Path) -> io::Result<()> {
     run_path_with_cstr(original, |original| {
         run_path_with_cstr(link, |link| {
             cfg_if::cfg_if! {
-                if #[cfg(any(target_os = "vxworks", target_os = "redox", target_os = "android", target_os = "espidf", target_os = "horizon"))] {
+                if #[cfg(any(target_os = "vxworks", target_os = "redox", target_os = "android", target_os = "espidf", target_os = "horizon", target_os = "vita"))] {
                     // VxWorks, Redox and ESP-IDF lack `linkat`, so use `link` instead. POSIX leaves
                     // it implementation-defined whether `link` follows symlinks, so rely on the
                     // `symlink_hard_link` test in library/std/src/fs/tests.rs to check the behavior.
@@ -1666,6 +1716,8 @@ fn open_to_and_set_permissions(
         .truncate(true)
         .open(to)?;
     let writer_metadata = writer.metadata()?;
+    // fchmod is broken on vita
+    #[cfg(not(target_os = "vita"))]
     if writer_metadata.is_file() {
         // Set the correct file permissions, in case the file already existed.
         // Don't set the permissions on already existing non-files like
@@ -1680,6 +1732,7 @@ fn open_to_and_set_permissions(
     target_os = "android",
     target_os = "macos",
     target_os = "ios",
+    target_os = "tvos",
     target_os = "watchos",
 )))]
 pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
@@ -1707,7 +1760,7 @@ pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
     }
 }
 
-#[cfg(any(target_os = "macos", target_os = "ios", target_os = "watchos"))]
+#[cfg(any(target_os = "macos", target_os = "ios", target_os = "tvos", target_os = "watchos"))]
 pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
     use crate::sync::atomic::{AtomicBool, Ordering};
 
@@ -1844,11 +1897,12 @@ pub fn chroot(dir: &Path) -> io::Result<()> {
 
 pub use remove_dir_impl::remove_dir_all;
 
-// Fallback for REDOX, ESP-ID, Horizon, and Miri
+// Fallback for REDOX, ESP-ID, Horizon, Vita and Miri
 #[cfg(any(
     target_os = "redox",
     target_os = "espidf",
     target_os = "horizon",
+    target_os = "vita",
     target_os = "nto",
     miri
 ))]
@@ -1861,6 +1915,7 @@ mod remove_dir_impl {
     target_os = "redox",
     target_os = "espidf",
     target_os = "horizon",
+    target_os = "vita",
     target_os = "nto",
     miri
 )))]
diff --git a/library/std/src/sys/unix/kernel_copy.rs b/library/std/src/sys/unix/kernel_copy.rs
index 16c8e0c0e..7d49bbdcb 100644
--- a/library/std/src/sys/unix/kernel_copy.rs
+++ b/library/std/src/sys/unix/kernel_copy.rs
@@ -466,7 +466,7 @@ impl<T: CopyRead> CopyRead for Take<T> {
     }
 }
 
-impl<T: CopyRead> CopyRead for BufReader<T> {
+impl<T: ?Sized + CopyRead> CopyRead for BufReader<T> {
     fn drain_to<W: Write>(&mut self, writer: &mut W, outer_limit: u64) -> Result<u64> {
         let buf = self.buffer();
         let buf = &buf[0..min(buf.len(), outer_limit.try_into().unwrap_or(usize::MAX))];
@@ -495,7 +495,7 @@ impl<T: CopyRead> CopyRead for BufReader<T> {
     }
 }
 
-impl<T: CopyWrite> CopyWrite for BufWriter<T> {
+impl<T: ?Sized + CopyWrite> CopyWrite for BufWriter<T> {
     fn properties(&self) -> CopyParams {
         self.get_ref().properties()
     }
diff --git a/library/std/src/sys/unix/l4re.rs b/library/std/src/sys/unix/l4re.rs
index ee016887e..fe9559f2a 100644
--- a/library/std/src/sys/unix/l4re.rs
+++ b/library/std/src/sys/unix/l4re.rs
@@ -10,7 +10,7 @@ macro_rules! unimpl {
 pub mod net {
     #![allow(warnings)]
     use crate::fmt;
-    use crate::io::{self, IoSlice, IoSliceMut};
+    use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut};
     use crate::net::{Ipv4Addr, Ipv6Addr, Shutdown, SocketAddr};
     use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, RawFd};
     use crate::sys::fd::FileDesc;
@@ -218,6 +218,10 @@ pub mod net {
             unimpl!();
         }
 
+        pub fn read_buf(&self, _: BorrowedCursor<'_>) -> io::Result<()> {
+            unimpl!();
+        }
+
         pub fn read_vectored(&self, _: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
             unimpl!();
         }
diff --git a/library/std/src/sys/unix/locks/pthread_condvar.rs b/library/std/src/sys/unix/locks/pthread_condvar.rs
index 192fa216d..2dc1b0c60 100644
--- a/library/std/src/sys/unix/locks/pthread_condvar.rs
+++ b/library/std/src/sys/unix/locks/pthread_condvar.rs
@@ -32,6 +32,7 @@ impl LazyInit for AllocatedCondvar {
             if #[cfg(any(
                 target_os = "macos",
                 target_os = "ios",
+                target_os = "tvos",
                 target_os = "watchos",
                 target_os = "l4re",
                 target_os = "android",
@@ -124,6 +125,7 @@ impl Condvar {
     #[cfg(not(any(
         target_os = "macos",
         target_os = "ios",
+        target_os = "tvos",
         target_os = "watchos",
         target_os = "android",
         target_os = "espidf",
@@ -158,6 +160,7 @@ impl Condvar {
     #[cfg(any(
         target_os = "macos",
         target_os = "ios",
+        target_os = "tvos",
         target_os = "watchos",
         target_os = "android",
         target_os = "espidf",
diff --git a/library/std/src/sys/unix/mod.rs b/library/std/src/sys/unix/mod.rs
index bb9e65e68..326f1481e 100644
--- a/library/std/src/sys/unix/mod.rs
+++ b/library/std/src/sys/unix/mod.rs
@@ -88,6 +88,7 @@ pub unsafe fn init(argc: isize, argv: *const *const u8, sigpipe: u8) {
             // The poll on Darwin doesn't set POLLNVAL for closed fds.
             target_os = "macos",
             target_os = "ios",
+            target_os = "tvos",
             target_os = "watchos",
             target_os = "redox",
             target_os = "l4re",
@@ -164,12 +165,7 @@ 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",
-            target_os = "vita"
-        )))]
+        #[cfg(not(any(target_os = "emscripten", target_os = "fuchsia", target_os = "horizon")))]
         {
             // 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
@@ -207,7 +203,6 @@ pub unsafe fn init(argc: isize, argv: *const *const u8, sigpipe: u8) {
     target_os = "emscripten",
     target_os = "fuchsia",
     target_os = "horizon",
-    target_os = "vita"
 )))]
 static UNIX_SIGPIPE_ATTR_SPECIFIED: crate::sync::atomic::AtomicBool =
     crate::sync::atomic::AtomicBool::new(false);
@@ -217,7 +212,6 @@ static UNIX_SIGPIPE_ATTR_SPECIFIED: crate::sync::atomic::AtomicBool =
     target_os = "emscripten",
     target_os = "fuchsia",
     target_os = "horizon",
-    target_os = "vita",
 )))]
 pub(crate) fn unix_sigpipe_attr_specified() -> bool {
     UNIX_SIGPIPE_ATTR_SPECIFIED.load(crate::sync::atomic::Ordering::Relaxed)
@@ -395,7 +389,7 @@ cfg_if::cfg_if! {
     } else if #[cfg(target_os = "macos")] {
         #[link(name = "System")]
         extern "C" {}
-    } else if #[cfg(any(target_os = "ios", target_os = "watchos"))] {
+    } else if #[cfg(any(target_os = "ios", target_os = "tvos", target_os = "watchos"))] {
         #[link(name = "System")]
         #[link(name = "objc")]
         #[link(name = "Security", kind = "framework")]
@@ -408,6 +402,9 @@ cfg_if::cfg_if! {
     } else if #[cfg(all(target_os = "linux", target_env = "uclibc"))] {
         #[link(name = "dl")]
         extern "C" {}
+    } else if #[cfg(target_os = "vita")] {
+        #[link(name = "pthread", kind = "static", modifiers = "-bundle")]
+        extern "C" {}
     }
 }
 
diff --git a/library/std/src/sys/unix/net.rs b/library/std/src/sys/unix/net.rs
index 39edb136c..7258c222a 100644
--- a/library/std/src/sys/unix/net.rs
+++ b/library/std/src/sys/unix/net.rs
@@ -454,12 +454,18 @@ impl Socket {
         Ok(passcred != 0)
     }
 
-    #[cfg(not(any(target_os = "solaris", target_os = "illumos")))]
+    #[cfg(not(any(target_os = "solaris", target_os = "illumos", target_os = "vita")))]
     pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
         let mut nonblocking = nonblocking as libc::c_int;
         cvt(unsafe { libc::ioctl(self.as_raw_fd(), libc::FIONBIO, &mut nonblocking) }).map(drop)
     }
 
+    #[cfg(target_os = "vita")]
+    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
+        let option = nonblocking as libc::c_int;
+        setsockopt(self, libc::SOL_SOCKET, libc::SO_NONBLOCK, option)
+    }
+
     #[cfg(any(target_os = "solaris", target_os = "illumos"))]
     pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
         // FIONBIO is inadequate for sockets on illumos/Solaris, so use the
diff --git a/library/std/src/sys/unix/os.rs b/library/std/src/sys/unix/os.rs
index 8edfd3313..a68c14758 100644
--- a/library/std/src/sys/unix/os.rs
+++ b/library/std/src/sys/unix/os.rs
@@ -63,7 +63,13 @@ extern "C" {
     #[cfg_attr(any(target_os = "solaris", target_os = "illumos"), link_name = "___errno")]
     #[cfg_attr(target_os = "nto", link_name = "__get_errno_ptr")]
     #[cfg_attr(
-        any(target_os = "macos", target_os = "ios", target_os = "freebsd", target_os = "watchos"),
+        any(
+            target_os = "macos",
+            target_os = "ios",
+            target_os = "tvos",
+            target_os = "freebsd",
+            target_os = "watchos"
+        ),
         link_name = "__error"
     )]
     #[cfg_attr(target_os = "haiku", link_name = "_errnop")]
@@ -375,7 +381,7 @@ pub fn current_exe() -> io::Result<PathBuf> {
     Ok(PathBuf::from(OsString::from_vec(e)))
 }
 
-#[cfg(any(target_os = "macos", target_os = "ios", target_os = "watchos"))]
+#[cfg(any(target_os = "macos", target_os = "ios", target_os = "tvos", target_os = "watchos"))]
 pub fn current_exe() -> io::Result<PathBuf> {
     unsafe {
         let mut sz: u32 = 0;
@@ -609,6 +615,7 @@ pub fn home_dir() -> Option<PathBuf> {
     #[cfg(any(
         target_os = "android",
         target_os = "ios",
+        target_os = "tvos",
         target_os = "watchos",
         target_os = "emscripten",
         target_os = "redox",
@@ -623,6 +630,7 @@ pub fn home_dir() -> Option<PathBuf> {
     #[cfg(not(any(
         target_os = "android",
         target_os = "ios",
+        target_os = "tvos",
         target_os = "watchos",
         target_os = "emscripten",
         target_os = "redox",
diff --git a/library/std/src/sys/unix/os_str.rs b/library/std/src/sys/unix/os_str.rs
index 488217f39..f7333fd5a 100644
--- a/library/std/src/sys/unix/os_str.rs
+++ b/library/std/src/sys/unix/os_str.rs
@@ -193,17 +193,22 @@ impl Buf {
 
 impl Slice {
     #[inline]
-    fn from_u8_slice(s: &[u8]) -> &Slice {
+    pub fn as_os_str_bytes(&self) -> &[u8] {
+        &self.inner
+    }
+
+    #[inline]
+    pub unsafe fn from_os_str_bytes_unchecked(s: &[u8]) -> &Slice {
         unsafe { mem::transmute(s) }
     }
 
     #[inline]
     pub fn from_str(s: &str) -> &Slice {
-        Slice::from_u8_slice(s.as_bytes())
+        unsafe { Slice::from_os_str_bytes_unchecked(s.as_bytes()) }
     }
 
-    pub fn to_str(&self) -> Option<&str> {
-        str::from_utf8(&self.inner).ok()
+    pub fn to_str(&self) -> Result<&str, crate::str::Utf8Error> {
+        str::from_utf8(&self.inner)
     }
 
     pub fn to_string_lossy(&self) -> Cow<'_, str> {
diff --git a/library/std/src/sys/unix/os_str/tests.rs b/library/std/src/sys/unix/os_str/tests.rs
index 22ba0c923..91bc0e61a 100644
--- a/library/std/src/sys/unix/os_str/tests.rs
+++ b/library/std/src/sys/unix/os_str/tests.rs
@@ -2,7 +2,7 @@ use super::*;
 
 #[test]
 fn slice_debug_output() {
-    let input = Slice::from_u8_slice(b"\xF0hello,\tworld");
+    let input = unsafe { Slice::from_os_str_bytes_unchecked(b"\xF0hello,\tworld") };
     let expected = r#""\xF0hello,\tworld""#;
     let output = format!("{input:?}");
 
@@ -11,8 +11,7 @@ fn slice_debug_output() {
 
 #[test]
 fn display() {
-    assert_eq!(
-        "Hello\u{FFFD}\u{FFFD} There\u{FFFD} Goodbye",
-        Slice::from_u8_slice(b"Hello\xC0\x80 There\xE6\x83 Goodbye").to_string(),
-    );
+    assert_eq!("Hello\u{FFFD}\u{FFFD} There\u{FFFD} Goodbye", unsafe {
+        Slice::from_os_str_bytes_unchecked(b"Hello\xC0\x80 There\xE6\x83 Goodbye").to_string()
+    },);
 }
diff --git a/library/std/src/sys/unix/path.rs b/library/std/src/sys/unix/path.rs
index a98a69e2d..935245f63 100644
--- a/library/std/src/sys/unix/path.rs
+++ b/library/std/src/sys/unix/path.rs
@@ -30,7 +30,7 @@ pub(crate) fn absolute(path: &Path) -> io::Result<PathBuf> {
 
     // Get the components, skipping the redundant leading "." component if it exists.
     let mut components = path.strip_prefix(".").unwrap_or(path).components();
-    let path_os = path.as_os_str().bytes();
+    let path_os = path.as_os_str().as_os_str_bytes();
 
     let mut normalized = if path.is_absolute() {
         // "If a pathname begins with two successive <slash> characters, the
diff --git a/library/std/src/sys/unix/process/process_common.rs b/library/std/src/sys/unix/process/process_common.rs
index afd03d79c..640648e87 100644
--- a/library/std/src/sys/unix/process/process_common.rs
+++ b/library/std/src/sys/unix/process/process_common.rs
@@ -164,9 +164,9 @@ pub enum ProgramKind {
 
 impl ProgramKind {
     fn new(program: &OsStr) -> Self {
-        if program.bytes().starts_with(b"/") {
+        if program.as_os_str_bytes().starts_with(b"/") {
             Self::Absolute
-        } else if program.bytes().contains(&b'/') {
+        } else if program.as_os_str_bytes().contains(&b'/') {
             // If the program has more than one component in it, it is a relative path.
             Self::Relative
         } else {
diff --git a/library/std/src/sys/unix/process/process_unix.rs b/library/std/src/sys/unix/process/process_unix.rs
index 612d43fe2..0ce93af66 100644
--- a/library/std/src/sys/unix/process/process_unix.rs
+++ b/library/std/src/sys/unix/process/process_unix.rs
@@ -15,6 +15,8 @@ use crate::sys::weak::raw_syscall;
 
 #[cfg(any(
     target_os = "macos",
+    target_os = "watchos",
+    target_os = "tvos",
     target_os = "freebsd",
     all(target_os = "linux", target_env = "gnu"),
     all(target_os = "linux", target_env = "musl"),
@@ -28,15 +30,38 @@ use libc::RTP_ID as pid_t;
 #[cfg(not(target_os = "vxworks"))]
 use libc::{c_int, pid_t};
 
-#[cfg(not(any(target_os = "vxworks", target_os = "l4re")))]
+#[cfg(not(any(
+    target_os = "vxworks",
+    target_os = "l4re",
+    target_os = "tvos",
+    target_os = "watchos",
+)))]
 use libc::{gid_t, uid_t};
 
 cfg_if::cfg_if! {
     if #[cfg(all(target_os = "nto", target_env = "nto71"))] {
         use crate::thread;
         use libc::{c_char, posix_spawn_file_actions_t, posix_spawnattr_t};
-        // arbitrary number of tries:
-        const MAX_FORKSPAWN_TRIES: u32 = 4;
+        use crate::time::Duration;
+        use crate::sync::LazyLock;
+        // Get smallest amount of time we can sleep.
+        // Return a common value if it cannot be determined.
+        fn get_clock_resolution() -> Duration {
+            static MIN_DELAY: LazyLock<Duration, fn() -> Duration> = LazyLock::new(|| {
+                let mut mindelay = libc::timespec { tv_sec: 0, tv_nsec: 0 };
+                if unsafe { libc::clock_getres(libc::CLOCK_MONOTONIC, &mut mindelay) } == 0
+                {
+                    Duration::from_nanos(mindelay.tv_nsec as u64)
+                } else {
+                    Duration::from_millis(1)
+                }
+            });
+            *MIN_DELAY
+        }
+        // Arbitrary minimum sleep duration for retrying fork/spawn
+        const MIN_FORKSPAWN_SLEEP: Duration = Duration::from_nanos(1);
+        // Maximum duration of sleeping before giving up and returning an error
+        const MAX_FORKSPAWN_SLEEP: Duration = Duration::from_millis(1000);
     }
 }
 
@@ -66,7 +91,6 @@ impl Command {
         if let Some(ret) = self.posix_spawn(&theirs, envp.as_ref())? {
             return Ok((ret, ours));
         }
-
         let (input, output) = sys::pipe::anon_pipe()?;
 
         // Whatever happens after the fork is almost for sure going to touch or
@@ -148,9 +172,31 @@ impl Command {
         crate::sys_common::process::wait_with_output(proc, pipes)
     }
 
+    // WatchOS and TVOS headers mark the `fork`/`exec*` functions with
+    // `__WATCHOS_PROHIBITED __TVOS_PROHIBITED`, and indicate that the
+    // `posix_spawn*` functions should be used instead. It isn't entirely clear
+    // what `PROHIBITED` means here (e.g. if calls to these functions are
+    // allowed to exist in dead code), but it sounds bad, so we go out of our
+    // way to avoid that all-together.
+    #[cfg(any(target_os = "tvos", target_os = "watchos"))]
+    const ERR_APPLE_TV_WATCH_NO_FORK_EXEC: Error = io::const_io_error!(
+        ErrorKind::Unsupported,
+        "`fork`+`exec`-based process spawning is not supported on this target",
+    );
+
+    #[cfg(any(target_os = "tvos", target_os = "watchos"))]
+    unsafe fn do_fork(&mut self) -> Result<(pid_t, pid_t), io::Error> {
+        return Err(Self::ERR_APPLE_TV_WATCH_NO_FORK_EXEC);
+    }
+
     // Attempts to fork the process. If successful, returns Ok((0, -1))
     // in the child, and Ok((child_pid, -1)) in the parent.
-    #[cfg(not(any(target_os = "linux", all(target_os = "nto", target_env = "nto71"))))]
+    #[cfg(not(any(
+        target_os = "linux",
+        target_os = "watchos",
+        target_os = "tvos",
+        all(target_os = "nto", target_env = "nto71"),
+    )))]
     unsafe fn do_fork(&mut self) -> Result<(pid_t, pid_t), io::Error> {
         cvt(libc::fork()).map(|res| (res, -1))
     }
@@ -163,12 +209,25 @@ impl Command {
     unsafe fn do_fork(&mut self) -> Result<(pid_t, pid_t), io::Error> {
         use crate::sys::os::errno;
 
-        let mut tries_left = MAX_FORKSPAWN_TRIES;
+        let mut delay = MIN_FORKSPAWN_SLEEP;
+
         loop {
             let r = libc::fork();
-            if r == -1 as libc::pid_t && tries_left > 0 && errno() as libc::c_int == libc::EBADF {
-                thread::yield_now();
-                tries_left -= 1;
+            if r == -1 as libc::pid_t && errno() as libc::c_int == libc::EBADF {
+                if delay < get_clock_resolution() {
+                    // We cannot sleep this short (it would be longer).
+                    // Yield instead.
+                    thread::yield_now();
+                } else if delay < MAX_FORKSPAWN_SLEEP {
+                    thread::sleep(delay);
+                } else {
+                    return Err(io::const_io_error!(
+                        ErrorKind::WouldBlock,
+                        "forking returned EBADF too often",
+                    ));
+                }
+                delay *= 2;
+                continue;
             } else {
                 return cvt(r).map(|res| (res, -1));
             }
@@ -308,6 +367,7 @@ impl Command {
     // allocation). Instead we just close it manually. This will never
     // have the drop glue anyway because this code never returns (the
     // child will either exec() or invoke libc::exit)
+    #[cfg(not(any(target_os = "tvos", target_os = "watchos")))]
     unsafe fn do_exec(
         &mut self,
         stdio: ChildPipes,
@@ -414,8 +474,19 @@ impl Command {
         Err(io::Error::last_os_error())
     }
 
+    #[cfg(any(target_os = "tvos", target_os = "watchos"))]
+    unsafe fn do_exec(
+        &mut self,
+        _stdio: ChildPipes,
+        _maybe_envp: Option<&CStringArray>,
+    ) -> Result<!, io::Error> {
+        return Err(Self::ERR_APPLE_TV_WATCH_NO_FORK_EXEC);
+    }
+
     #[cfg(not(any(
         target_os = "macos",
+        target_os = "tvos",
+        target_os = "watchos",
         target_os = "freebsd",
         all(target_os = "linux", target_env = "gnu"),
         all(target_os = "linux", target_env = "musl"),
@@ -433,6 +504,9 @@ impl Command {
     // directly.
     #[cfg(any(
         target_os = "macos",
+        // FIXME: `target_os = "ios"`?
+        target_os = "tvos",
+        target_os = "watchos",
         target_os = "freebsd",
         all(target_os = "linux", target_env = "gnu"),
         all(target_os = "linux", target_env = "musl"),
@@ -480,17 +554,28 @@ impl Command {
             attrp: *const posix_spawnattr_t,
             argv: *const *mut c_char,
             envp: *const *mut c_char,
-        ) -> i32 {
-            let mut tries_left = MAX_FORKSPAWN_TRIES;
+        ) -> io::Result<i32> {
+            let mut delay = MIN_FORKSPAWN_SLEEP;
             loop {
                 match libc::posix_spawnp(pid, file, file_actions, attrp, argv, envp) {
-                    libc::EBADF if tries_left > 0 => {
-                        thread::yield_now();
-                        tries_left -= 1;
+                    libc::EBADF => {
+                        if delay < get_clock_resolution() {
+                            // We cannot sleep this short (it would be longer).
+                            // Yield instead.
+                            thread::yield_now();
+                        } else if delay < MAX_FORKSPAWN_SLEEP {
+                            thread::sleep(delay);
+                        } else {
+                            return Err(io::const_io_error!(
+                                ErrorKind::WouldBlock,
+                                "posix_spawnp returned EBADF too often",
+                            ));
+                        }
+                        delay *= 2;
                         continue;
                     }
                     r => {
-                        return r;
+                        return Ok(r);
                     }
                 }
             }
@@ -508,7 +593,7 @@ impl Command {
         }
         let addchdir = match self.get_cwd() {
             Some(cwd) => {
-                if cfg!(target_os = "macos") {
+                if cfg!(any(target_os = "macos", target_os = "tvos", target_os = "watchos")) {
                     // There is a bug in macOS where a relative executable
                     // path like "../myprogram" will cause `posix_spawn` to
                     // successfully launch the program, but erroneously return
@@ -620,14 +705,20 @@ impl Command {
             let spawn_fn = libc::posix_spawnp;
             #[cfg(target_os = "nto")]
             let spawn_fn = retrying_libc_posix_spawnp;
-            cvt_nz(spawn_fn(
+
+            let spawn_res = spawn_fn(
                 &mut p.pid,
                 self.get_program_cstr().as_ptr(),
                 file_actions.0.as_ptr(),
                 attrs.0.as_ptr(),
                 self.get_argv().as_ptr() as *const _,
                 envp as *const _,
-            ))?;
+            );
+
+            #[cfg(target_os = "nto")]
+            let spawn_res = spawn_res?;
+
+            cvt_nz(spawn_res)?;
             Ok(Some(p))
         }
     }
@@ -671,12 +762,9 @@ impl Process {
     pub fn kill(&mut self) -> io::Result<()> {
         // If we've already waited on this process then the pid can be recycled
         // and used for another process, and we probably shouldn't be killing
-        // random processes, so just return an error.
+        // random processes, so return Ok because the process has exited already.
         if self.status.is_some() {
-            Err(io::const_io_error!(
-                ErrorKind::InvalidInput,
-                "invalid argument: can't kill an exited process",
-            ))
+            Ok(())
         } else {
             cvt(unsafe { libc::kill(self.pid, libc::SIGKILL) }).map(drop)
         }
@@ -788,31 +876,47 @@ fn signal_string(signal: i32) -> &'static str {
         libc::SIGILL => " (SIGILL)",
         libc::SIGTRAP => " (SIGTRAP)",
         libc::SIGABRT => " (SIGABRT)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGBUS => " (SIGBUS)",
         libc::SIGFPE => " (SIGFPE)",
         libc::SIGKILL => " (SIGKILL)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGUSR1 => " (SIGUSR1)",
         libc::SIGSEGV => " (SIGSEGV)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGUSR2 => " (SIGUSR2)",
         libc::SIGPIPE => " (SIGPIPE)",
         libc::SIGALRM => " (SIGALRM)",
         libc::SIGTERM => " (SIGTERM)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGCHLD => " (SIGCHLD)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGCONT => " (SIGCONT)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGSTOP => " (SIGSTOP)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGTSTP => " (SIGTSTP)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGTTIN => " (SIGTTIN)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGTTOU => " (SIGTTOU)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGURG => " (SIGURG)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGXCPU => " (SIGXCPU)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGXFSZ => " (SIGXFSZ)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGVTALRM => " (SIGVTALRM)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGPROF => " (SIGPROF)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGWINCH => " (SIGWINCH)",
-        #[cfg(not(target_os = "haiku"))]
+        #[cfg(not(any(target_os = "haiku", target_os = "l4re")))]
         libc::SIGIO => " (SIGIO)",
         #[cfg(target_os = "haiku")]
         libc::SIGPOLL => " (SIGPOLL)",
+        #[cfg(not(target_os = "l4re"))]
         libc::SIGSYS => " (SIGSYS)",
         // For information on Linux signals, run `man 7 signal`
         #[cfg(all(
diff --git a/library/std/src/sys/unix/process/process_vxworks.rs b/library/std/src/sys/unix/process/process_vxworks.rs
index c40e7ada0..f70d3cb39 100644
--- a/library/std/src/sys/unix/process/process_vxworks.rs
+++ b/library/std/src/sys/unix/process/process_vxworks.rs
@@ -144,12 +144,9 @@ impl Process {
     pub fn kill(&mut self) -> io::Result<()> {
         // If we've already waited on this process then the pid can be recycled
         // and used for another process, and we probably shouldn't be killing
-        // random processes, so just return an error.
+        // random processes, so return Ok because the process has exited already.
         if self.status.is_some() {
-            Err(io::const_io_error!(
-                ErrorKind::InvalidInput,
-                "invalid argument: can't kill an exited process",
-            ))
+            Ok(())
         } else {
             cvt(unsafe { libc::kill(self.pid, libc::SIGKILL) }).map(drop)
         }
diff --git a/library/std/src/sys/unix/rand.rs b/library/std/src/sys/unix/rand.rs
index d8b63546b..d471be33e 100644
--- a/library/std/src/sys/unix/rand.rs
+++ b/library/std/src/sys/unix/rand.rs
@@ -14,6 +14,7 @@ pub fn hashmap_random_keys() -> (u64, u64) {
     unix,
     not(target_os = "macos"),
     not(target_os = "ios"),
+    not(target_os = "tvos"),
     not(target_os = "watchos"),
     not(target_os = "openbsd"),
     not(target_os = "freebsd"),
@@ -198,7 +199,7 @@ mod imp {
 // once per thread in `hashmap_random_keys`. Therefore `SecRandomCopyBytes` is
 // only used on iOS where direct access to `/dev/urandom` is blocked by the
 // sandbox.
-#[cfg(any(target_os = "ios", target_os = "watchos"))]
+#[cfg(any(target_os = "ios", target_os = "tvos", target_os = "watchos"))]
 mod imp {
     use crate::io;
     use crate::ptr;
diff --git a/library/std/src/sys/unix/thread.rs b/library/std/src/sys/unix/thread.rs
index 7307d9b2c..4f2d9cf36 100644
--- a/library/std/src/sys/unix/thread.rs
+++ b/library/std/src/sys/unix/thread.rs
@@ -150,7 +150,7 @@ impl Thread {
         }
     }
 
-    #[cfg(any(target_os = "macos", target_os = "ios", target_os = "watchos"))]
+    #[cfg(any(target_os = "macos", target_os = "ios", target_os = "tvos", target_os = "watchos"))]
     pub fn set_name(name: &CStr) {
         unsafe {
             let name = truncate_cstr::<{ libc::MAXTHREADNAMESIZE }>(name);
@@ -284,7 +284,13 @@ impl Drop for Thread {
     }
 }
 
-#[cfg(any(target_os = "linux", target_os = "macos", target_os = "ios", target_os = "watchos"))]
+#[cfg(any(
+    target_os = "linux",
+    target_os = "macos",
+    target_os = "ios",
+    target_os = "tvos",
+    target_os = "watchos",
+))]
 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]) {
@@ -300,6 +306,7 @@ pub fn available_parallelism() -> io::Result<NonZeroUsize> {
             target_os = "emscripten",
             target_os = "fuchsia",
             target_os = "ios",
+            target_os = "tvos",
             target_os = "linux",
             target_os = "macos",
             target_os = "solaris",
@@ -345,6 +352,29 @@ pub fn available_parallelism() -> io::Result<NonZeroUsize> {
                 }
             }
 
+            #[cfg(target_os = "netbsd")]
+            {
+                unsafe {
+                    let set = libc::_cpuset_create();
+                    if !set.is_null() {
+                        let mut count: usize = 0;
+                        if libc::pthread_getaffinity_np(libc::pthread_self(), libc::_cpuset_size(set), set) == 0 {
+                            for i in 0..u64::MAX {
+                                match libc::_cpuset_isset(i, set) {
+                                    -1 => break,
+                                    0 => continue,
+                                    _ => count = count + 1,
+                                }
+                            }
+                        }
+                        libc::_cpuset_destroy(set);
+                        if let Some(count) = NonZeroUsize::new(count) {
+                            return Ok(count);
+                        }
+                    }
+                }
+            }
+
             let mut cpus: libc::c_uint = 0;
             let mut cpus_size = crate::mem::size_of_val(&cpus);
 
diff --git a/library/std/src/sys/unix/thread_parking/pthread.rs b/library/std/src/sys/unix/thread_parking/pthread.rs
index 43046ed07..ae805d843 100644
--- a/library/std/src/sys/unix/thread_parking/pthread.rs
+++ b/library/std/src/sys/unix/thread_parking/pthread.rs
@@ -46,6 +46,7 @@ unsafe fn wait_timeout(
     #[cfg(any(
         target_os = "macos",
         target_os = "ios",
+        target_os = "tvos",
         target_os = "watchos",
         target_os = "espidf",
         target_os = "horizon",
@@ -73,6 +74,7 @@ unsafe fn wait_timeout(
     #[cfg(not(any(
         target_os = "macos",
         target_os = "ios",
+        target_os = "tvos",
         target_os = "watchos",
         target_os = "espidf",
         target_os = "horizon",
@@ -120,10 +122,12 @@ impl Parker {
             if #[cfg(any(
                 target_os = "macos",
                 target_os = "ios",
+                target_os = "tvos",
                 target_os = "watchos",
                 target_os = "l4re",
                 target_os = "android",
-                target_os = "redox"
+                target_os = "redox",
+                target_os = "vita",
             ))] {
                 addr_of_mut!((*parker).cvar).write(UnsafeCell::new(libc::PTHREAD_COND_INITIALIZER));
             } else if #[cfg(any(target_os = "espidf", target_os = "horizon"))] {
diff --git a/library/std/src/sys/unix/time.rs b/library/std/src/sys/unix/time.rs
index a9fbc7ab1..17b4130c2 100644
--- a/library/std/src/sys/unix/time.rs
+++ b/library/std/src/sys/unix/time.rs
@@ -219,7 +219,8 @@ impl From<__timespec64> for Timespec {
 #[cfg(any(
     all(target_os = "macos", any(not(target_arch = "aarch64"))),
     target_os = "ios",
-    target_os = "watchos"
+    target_os = "watchos",
+    target_os = "tvos"
 ))]
 mod inner {
     use crate::sync::atomic::{AtomicU64, Ordering};
@@ -339,7 +340,8 @@ mod inner {
 #[cfg(not(any(
     all(target_os = "macos", any(not(target_arch = "aarch64"))),
     target_os = "ios",
-    target_os = "watchos"
+    target_os = "watchos",
+    target_os = "tvos"
 )))]
 mod inner {
     use crate::fmt;
diff --git a/library/std/src/sys/unix/weak.rs b/library/std/src/sys/unix/weak.rs
index 62ffee70b..61088ff16 100644
--- a/library/std/src/sys/unix/weak.rs
+++ b/library/std/src/sys/unix/weak.rs
@@ -28,7 +28,7 @@ use crate::ptr;
 use crate::sync::atomic::{self, AtomicPtr, Ordering};
 
 // We can use true weak linkage on ELF targets.
-#[cfg(not(any(target_os = "macos", target_os = "ios")))]
+#[cfg(not(any(target_os = "macos", target_os = "ios", target_os = "tvos")))]
 pub(crate) macro weak {
     (fn $name:ident($($t:ty),*) -> $ret:ty) => (
         let ref $name: ExternWeak<unsafe extern "C" fn($($t),*) -> $ret> = {
@@ -43,7 +43,7 @@ pub(crate) macro weak {
 }
 
 // On non-ELF targets, use the dlsym approximation of weak linkage.
-#[cfg(any(target_os = "macos", target_os = "ios"))]
+#[cfg(any(target_os = "macos", target_os = "ios", target_os = "tvos"))]
 pub(crate) use self::dlsym as weak;
 
 pub(crate) struct ExternWeak<F: Copy> {
diff --git a/library/std/src/sys/wasi/fd.rs b/library/std/src/sys/wasi/fd.rs
index 9a8b2a0be..1b50c2ea6 100644
--- a/library/std/src/sys/wasi/fd.rs
+++ b/library/std/src/sys/wasi/fd.rs
@@ -96,7 +96,7 @@ impl WasiFd {
         unsafe { wasi::fd_sync(self.as_raw_fd() as wasi::Fd).map_err(err2io) }
     }
 
-    pub fn advise(&self, offset: u64, len: u64, advice: wasi::Advice) -> io::Result<()> {
+    pub(crate) fn advise(&self, offset: u64, len: u64, advice: wasi::Advice) -> io::Result<()> {
         unsafe {
             wasi::fd_advise(self.as_raw_fd() as wasi::Fd, offset, len, advice).map_err(err2io)
         }
@@ -179,7 +179,7 @@ impl WasiFd {
         }
     }
 
-    pub fn filestat_get(&self) -> io::Result<wasi::Filestat> {
+    pub(crate) fn filestat_get(&self) -> io::Result<wasi::Filestat> {
         unsafe { wasi::fd_filestat_get(self.as_raw_fd() as wasi::Fd).map_err(err2io) }
     }
 
@@ -199,7 +199,7 @@ impl WasiFd {
         unsafe { wasi::fd_filestat_set_size(self.as_raw_fd() as wasi::Fd, size).map_err(err2io) }
     }
 
-    pub fn path_filestat_get(
+    pub(crate) fn path_filestat_get(
         &self,
         flags: wasi::Lookupflags,
         path: &str,
diff --git a/library/std/src/sys/wasi/fs.rs b/library/std/src/sys/wasi/fs.rs
index 8d1dbf591..437aae3ae 100644
--- a/library/std/src/sys/wasi/fs.rs
+++ b/library/std/src/sys/wasi/fs.rs
@@ -104,7 +104,7 @@ impl FileAttr {
         Ok(SystemTime::from_wasi_timestamp(self.meta.ctim))
     }
 
-    pub fn as_wasi(&self) -> &wasi::Filestat {
+    pub(crate) fn as_wasi(&self) -> &wasi::Filestat {
         &self.meta
     }
 }
@@ -142,7 +142,7 @@ impl FileType {
         self.bits == wasi::FILETYPE_SYMBOLIC_LINK
     }
 
-    pub fn bits(&self) -> wasi::Filetype {
+    pub(crate) fn bits(&self) -> wasi::Filetype {
         self.bits
     }
 }
diff --git a/library/std/src/sys/windows/args.rs b/library/std/src/sys/windows/args.rs
index 5bfd8b52e..6b597f499 100644
--- a/library/std/src/sys/windows/args.rs
+++ b/library/std/src/sys/windows/args.rs
@@ -226,7 +226,7 @@ pub(crate) fn append_arg(cmd: &mut Vec<u16>, arg: &Arg, force_quotes: bool) -> i
     // that it actually gets passed through on the command line or otherwise
     // it will be dropped entirely when parsed on the other end.
     ensure_no_nuls(arg)?;
-    let arg_bytes = arg.bytes();
+    let arg_bytes = arg.as_os_str_bytes();
     let (quote, escape) = match quote {
         Quote::Always => (true, true),
         Quote::Auto => {
@@ -297,7 +297,9 @@ pub(crate) fn make_bat_command_line(
         // * `|<>` pipe/redirect characters.
         const SPECIAL: &[u8] = b"\t &()[]{}^=;!'+,`~%|<>";
         let force_quotes = match arg {
-            Arg::Regular(arg) if !force_quotes => arg.bytes().iter().any(|c| SPECIAL.contains(c)),
+            Arg::Regular(arg) if !force_quotes => {
+                arg.as_os_str_bytes().iter().any(|c| SPECIAL.contains(c))
+            }
             _ => force_quotes,
         };
         append_arg(&mut cmd, arg, force_quotes)?;
diff --git a/library/std/src/sys/windows/c.rs b/library/std/src/sys/windows/c.rs
index 2bc40c474..d9ccba0e9 100644
--- a/library/std/src/sys/windows/c.rs
+++ b/library/std/src/sys/windows/c.rs
@@ -12,13 +12,13 @@ use crate::os::windows::io::{AsRawHandle, BorrowedHandle};
 use crate::ptr;
 use core::ffi::NonZero_c_ulong;
 
-#[path = "c/windows_sys.rs"] // c.rs is included from two places so we need to specify this
 mod windows_sys;
 pub use windows_sys::*;
 
 pub type DWORD = c_ulong;
 pub type NonZeroDWORD = NonZero_c_ulong;
 pub type LARGE_INTEGER = c_longlong;
+#[cfg_attr(target_vendor = "uwp", allow(unused))]
 pub type LONG = c_long;
 pub type UINT = c_uint;
 pub type WCHAR = u16;
@@ -267,6 +267,8 @@ pub unsafe fn getaddrinfo(
     windows_sys::getaddrinfo(node.cast::<u8>(), service.cast::<u8>(), hints, res)
 }
 
+cfg_if::cfg_if! {
+if #[cfg(not(target_vendor = "uwp"))] {
 pub unsafe fn NtReadFile(
     filehandle: BorrowedHandle<'_>,
     event: HANDLE,
@@ -313,6 +315,8 @@ pub unsafe fn NtWriteFile(
         key.map(|k| k as *const u32).unwrap_or(ptr::null()),
     )
 }
+}
+}
 
 // Functions that aren't available on every version of Windows that we support,
 // but we still use them and just provide some form of a fallback implementation.
@@ -376,4 +380,98 @@ compat_fn_with_fallback! {
     ) -> NTSTATUS {
         panic!("keyed events not available")
     }
+
+    // These functions are available on UWP when lazily loaded. They will fail WACK if loaded statically.
+    #[cfg(target_vendor = "uwp")]
+    pub fn NtCreateFile(
+        filehandle: *mut HANDLE,
+        desiredaccess: FILE_ACCESS_RIGHTS,
+        objectattributes: *const OBJECT_ATTRIBUTES,
+        iostatusblock: *mut IO_STATUS_BLOCK,
+        allocationsize: *const i64,
+        fileattributes: FILE_FLAGS_AND_ATTRIBUTES,
+        shareaccess: FILE_SHARE_MODE,
+        createdisposition: NTCREATEFILE_CREATE_DISPOSITION,
+        createoptions: NTCREATEFILE_CREATE_OPTIONS,
+        eabuffer: *const ::core::ffi::c_void,
+        ealength: u32
+    ) -> NTSTATUS {
+        STATUS_NOT_IMPLEMENTED
+    }
+    #[cfg(target_vendor = "uwp")]
+    pub fn NtReadFile(
+        filehandle: BorrowedHandle<'_>,
+        event: HANDLE,
+        apcroutine: PIO_APC_ROUTINE,
+        apccontext: *mut c_void,
+        iostatusblock: &mut IO_STATUS_BLOCK,
+        buffer: *mut crate::mem::MaybeUninit<u8>,
+        length: ULONG,
+        byteoffset: Option<&LARGE_INTEGER>,
+        key: Option<&ULONG>
+    ) -> NTSTATUS {
+        STATUS_NOT_IMPLEMENTED
+    }
+    #[cfg(target_vendor = "uwp")]
+    pub fn NtWriteFile(
+        filehandle: BorrowedHandle<'_>,
+        event: HANDLE,
+        apcroutine: PIO_APC_ROUTINE,
+        apccontext: *mut c_void,
+        iostatusblock: &mut IO_STATUS_BLOCK,
+        buffer: *const u8,
+        length: ULONG,
+        byteoffset: Option<&LARGE_INTEGER>,
+        key: Option<&ULONG>
+    ) -> NTSTATUS {
+        STATUS_NOT_IMPLEMENTED
+    }
+    #[cfg(target_vendor = "uwp")]
+    pub fn RtlNtStatusToDosError(Status: NTSTATUS) -> u32 {
+        Status as u32
+    }
+}
+
+// # Arm32 shim
+//
+// AddVectoredExceptionHandler and WSAStartup use platform-specific types.
+// However, Microsoft no longer supports thumbv7a so definitions for those targets
+// are not included in the win32 metadata. We work around that by defining them here.
+//
+// Where possible, these definitions should be kept in sync with https://docs.rs/windows-sys
+cfg_if::cfg_if! {
+if #[cfg(not(target_vendor = "uwp"))] {
+    #[link(name = "kernel32")]
+    extern "system" {
+        pub fn AddVectoredExceptionHandler(
+            first: u32,
+            handler: PVECTORED_EXCEPTION_HANDLER,
+        ) -> *mut c_void;
+    }
+    pub type PVECTORED_EXCEPTION_HANDLER = Option<
+        unsafe extern "system" fn(exceptioninfo: *mut EXCEPTION_POINTERS) -> i32,
+    >;
+    #[repr(C)]
+    pub struct EXCEPTION_POINTERS {
+        pub ExceptionRecord: *mut EXCEPTION_RECORD,
+        pub ContextRecord: *mut CONTEXT,
+    }
+    #[cfg(target_arch = "arm")]
+    pub enum CONTEXT {}
+}}
+
+#[link(name = "ws2_32")]
+extern "system" {
+    pub fn WSAStartup(wversionrequested: u16, lpwsadata: *mut WSADATA) -> i32;
+}
+#[cfg(target_arch = "arm")]
+#[repr(C)]
+pub struct WSADATA {
+    pub wVersion: u16,
+    pub wHighVersion: u16,
+    pub szDescription: [u8; 257],
+    pub szSystemStatus: [u8; 129],
+    pub iMaxSockets: u16,
+    pub iMaxUdpDg: u16,
+    pub lpVendorInfo: PSTR,
 }
diff --git a/library/std/src/sys/windows/c/windows_sys.lst b/library/std/src/sys/windows/c/windows_sys.lst
index 3e454199f..631aedd26 100644
--- a/library/std/src/sys/windows/c/windows_sys.lst
+++ b/library/std/src/sys/windows/c/windows_sys.lst
@@ -1930,6 +1930,7 @@ Windows.Win32.Foundation.SetLastError
 Windows.Win32.Foundation.STATUS_DELETE_PENDING
 Windows.Win32.Foundation.STATUS_END_OF_FILE
 Windows.Win32.Foundation.STATUS_INVALID_PARAMETER
+Windows.Win32.Foundation.STATUS_NOT_IMPLEMENTED
 Windows.Win32.Foundation.STATUS_PENDING
 Windows.Win32.Foundation.STATUS_SUCCESS
 Windows.Win32.Foundation.TRUE
@@ -2170,7 +2171,6 @@ Windows.Win32.Networking.WinSock.WSARecv
 Windows.Win32.Networking.WinSock.WSASend
 Windows.Win32.Networking.WinSock.WSASERVICE_NOT_FOUND
 Windows.Win32.Networking.WinSock.WSASocketW
-Windows.Win32.Networking.WinSock.WSAStartup
 Windows.Win32.Networking.WinSock.WSASYSCALLFAILURE
 Windows.Win32.Networking.WinSock.WSASYSNOTREADY
 Windows.Win32.Networking.WinSock.WSATRY_AGAIN
@@ -2418,12 +2418,10 @@ Windows.Win32.System.Console.STD_HANDLE
 Windows.Win32.System.Console.STD_INPUT_HANDLE
 Windows.Win32.System.Console.STD_OUTPUT_HANDLE
 Windows.Win32.System.Console.WriteConsoleW
-Windows.Win32.System.Diagnostics.Debug.AddVectoredExceptionHandler
 Windows.Win32.System.Diagnostics.Debug.ARM64_NT_NEON128
 Windows.Win32.System.Diagnostics.Debug.CONTEXT
 Windows.Win32.System.Diagnostics.Debug.CONTEXT
 Windows.Win32.System.Diagnostics.Debug.CONTEXT
-Windows.Win32.System.Diagnostics.Debug.EXCEPTION_POINTERS
 Windows.Win32.System.Diagnostics.Debug.EXCEPTION_RECORD
 Windows.Win32.System.Diagnostics.Debug.FACILITY_CODE
 Windows.Win32.System.Diagnostics.Debug.FACILITY_NT_BIT
@@ -2436,7 +2434,6 @@ Windows.Win32.System.Diagnostics.Debug.FORMAT_MESSAGE_IGNORE_INSERTS
 Windows.Win32.System.Diagnostics.Debug.FORMAT_MESSAGE_OPTIONS
 Windows.Win32.System.Diagnostics.Debug.FormatMessageW
 Windows.Win32.System.Diagnostics.Debug.M128A
-Windows.Win32.System.Diagnostics.Debug.PVECTORED_EXCEPTION_HANDLER
 Windows.Win32.System.Diagnostics.Debug.XSAVE_FORMAT
 Windows.Win32.System.Diagnostics.Debug.XSAVE_FORMAT
 Windows.Win32.System.Environment.FreeEnvironmentStringsW
diff --git a/library/std/src/sys/windows/c/windows_sys.rs b/library/std/src/sys/windows/c/windows_sys.rs
index 36a30f6ba..023770871 100644
--- a/library/std/src/sys/windows/c/windows_sys.rs
+++ b/library/std/src/sys/windows/c/windows_sys.rs
@@ -40,13 +40,6 @@ extern "system" {
 }
 #[link(name = "kernel32")]
 extern "system" {
-    pub fn AddVectoredExceptionHandler(
-        first: u32,
-        handler: PVECTORED_EXCEPTION_HANDLER,
-    ) -> *mut ::core::ffi::c_void;
-}
-#[link(name = "kernel32")]
-extern "system" {
     pub fn CancelIo(hfile: HANDLE) -> BOOL;
 }
 #[link(name = "kernel32")]
@@ -712,10 +705,6 @@ extern "system" {
 }
 #[link(name = "ws2_32")]
 extern "system" {
-    pub fn WSAStartup(wversionrequested: u16, lpwsadata: *mut WSADATA) -> i32;
-}
-#[link(name = "ws2_32")]
-extern "system" {
     pub fn accept(s: SOCKET, addr: *mut SOCKADDR, addrlen: *mut i32) -> SOCKET;
 }
 #[link(name = "ws2_32")]
@@ -3029,17 +3018,6 @@ pub const ERROR_XML_PARSE_ERROR: WIN32_ERROR = 1465u32;
 pub type EXCEPTION_DISPOSITION = i32;
 pub const EXCEPTION_MAXIMUM_PARAMETERS: u32 = 15u32;
 #[repr(C)]
-pub struct EXCEPTION_POINTERS {
-    pub ExceptionRecord: *mut EXCEPTION_RECORD,
-    pub ContextRecord: *mut CONTEXT,
-}
-impl ::core::marker::Copy for EXCEPTION_POINTERS {}
-impl ::core::clone::Clone for EXCEPTION_POINTERS {
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-#[repr(C)]
 pub struct EXCEPTION_RECORD {
     pub ExceptionCode: NTSTATUS,
     pub ExceptionFlags: u32,
@@ -3748,9 +3726,6 @@ pub const PROFILE_SERVER: PROCESS_CREATION_FLAGS = 1073741824u32;
 pub const PROFILE_USER: PROCESS_CREATION_FLAGS = 268435456u32;
 pub const PROGRESS_CONTINUE: u32 = 0u32;
 pub type PSTR = *mut u8;
-pub type PVECTORED_EXCEPTION_HANDLER = ::core::option::Option<
-    unsafe extern "system" fn(exceptioninfo: *mut EXCEPTION_POINTERS) -> i32,
->;
 pub type PWSTR = *mut u16;
 pub const READ_CONTROL: FILE_ACCESS_RIGHTS = 131072u32;
 pub const REALTIME_PRIORITY_CLASS: PROCESS_CREATION_FLAGS = 256u32;
@@ -3888,6 +3863,7 @@ pub type STARTUPINFOW_FLAGS = u32;
 pub const STATUS_DELETE_PENDING: NTSTATUS = -1073741738i32;
 pub const STATUS_END_OF_FILE: NTSTATUS = -1073741807i32;
 pub const STATUS_INVALID_PARAMETER: NTSTATUS = -1073741811i32;
+pub const STATUS_NOT_IMPLEMENTED: NTSTATUS = -1073741822i32;
 pub const STATUS_PENDING: NTSTATUS = 259i32;
 pub const STATUS_SUCCESS: NTSTATUS = 0i32;
 pub const STD_ERROR_HANDLE: STD_HANDLE = 4294967284u32;
diff --git a/library/std/src/sys/windows/net.rs b/library/std/src/sys/windows/net.rs
index 2404bbe2b..1ae42cb7e 100644
--- a/library/std/src/sys/windows/net.rs
+++ b/library/std/src/sys/windows/net.rs
@@ -159,7 +159,7 @@ impl Socket {
                 }
 
                 let mut timeout = c::timeval {
-                    tv_sec: timeout.as_secs() as c_long,
+                    tv_sec: cmp::min(timeout.as_secs(), c_long::MAX as u64) as c_long,
                     tv_usec: (timeout.subsec_nanos() / 1000) as c_long,
                 };
 
diff --git a/library/std/src/sys/windows/os_str.rs b/library/std/src/sys/windows/os_str.rs
index 2f2b0e56e..16c4f55c6 100644
--- a/library/std/src/sys/windows/os_str.rs
+++ b/library/std/src/sys/windows/os_str.rs
@@ -152,11 +152,21 @@ impl Buf {
 
 impl Slice {
     #[inline]
+    pub fn as_os_str_bytes(&self) -> &[u8] {
+        self.inner.as_bytes()
+    }
+
+    #[inline]
+    pub unsafe fn from_os_str_bytes_unchecked(s: &[u8]) -> &Slice {
+        mem::transmute(Wtf8::from_bytes_unchecked(s))
+    }
+
+    #[inline]
     pub fn from_str(s: &str) -> &Slice {
         unsafe { mem::transmute(Wtf8::from_str(s)) }
     }
 
-    pub fn to_str(&self) -> Option<&str> {
+    pub fn to_str(&self) -> Result<&str, crate::str::Utf8Error> {
         self.inner.as_str()
     }
 
diff --git a/library/std/src/sys/windows/path.rs b/library/std/src/sys/windows/path.rs
index c3573d14c..c9c2d10e6 100644
--- a/library/std/src/sys/windows/path.rs
+++ b/library/std/src/sys/windows/path.rs
@@ -1,7 +1,6 @@
 use super::{c, fill_utf16_buf, to_u16s};
 use crate::ffi::{OsStr, OsString};
 use crate::io;
-use crate::mem;
 use crate::path::{Path, PathBuf, Prefix};
 use crate::ptr;
 
@@ -11,16 +10,6 @@ mod tests;
 pub const MAIN_SEP_STR: &str = "\\";
 pub const MAIN_SEP: char = '\\';
 
-/// # Safety
-///
-/// `bytes` must be a valid wtf8 encoded slice
-#[inline]
-unsafe fn bytes_as_os_str(bytes: &[u8]) -> &OsStr {
-    // &OsStr is layout compatible with &Slice, which is compatible with &Wtf8,
-    // which is compatible with &[u8].
-    mem::transmute(bytes)
-}
-
 #[inline]
 pub fn is_sep_byte(b: u8) -> bool {
     b == b'/' || b == b'\\'
@@ -33,12 +22,12 @@ pub fn is_verbatim_sep(b: u8) -> bool {
 
 /// Returns true if `path` looks like a lone filename.
 pub(crate) fn is_file_name(path: &OsStr) -> bool {
-    !path.bytes().iter().copied().any(is_sep_byte)
+    !path.as_os_str_bytes().iter().copied().any(is_sep_byte)
 }
 pub(crate) fn has_trailing_slash(path: &OsStr) -> bool {
-    let is_verbatim = path.bytes().starts_with(br"\\?\");
+    let is_verbatim = path.as_os_str_bytes().starts_with(br"\\?\");
     let is_separator = if is_verbatim { is_verbatim_sep } else { is_sep_byte };
-    if let Some(&c) = path.bytes().last() { is_separator(c) } else { false }
+    if let Some(&c) = path.as_os_str_bytes().last() { is_separator(c) } else { false }
 }
 
 /// Appends a suffix to a path.
@@ -60,7 +49,7 @@ impl<'a, const LEN: usize> PrefixParser<'a, LEN> {
     fn get_prefix(path: &OsStr) -> [u8; LEN] {
         let mut prefix = [0; LEN];
         // SAFETY: Only ASCII characters are modified.
-        for (i, &ch) in path.bytes().iter().take(LEN).enumerate() {
+        for (i, &ch) in path.as_os_str_bytes().iter().take(LEN).enumerate() {
             prefix[i] = if ch == b'/' { b'\\' } else { ch };
         }
         prefix
@@ -93,7 +82,7 @@ impl<'a> PrefixParserSlice<'a, '_> {
     }
 
     fn prefix_bytes(&self) -> &'a [u8] {
-        &self.path.bytes()[..self.index]
+        &self.path.as_os_str_bytes()[..self.index]
     }
 
     fn finish(self) -> &'a OsStr {
@@ -101,7 +90,7 @@ impl<'a> PrefixParserSlice<'a, '_> {
         // &[u8] and back. This is safe to do because (1) we only look at ASCII
         // contents of the encoding and (2) new &OsStr values are produced only
         // from ASCII-bounded slices of existing &OsStr values.
-        unsafe { bytes_as_os_str(&self.path.bytes()[self.index..]) }
+        unsafe { OsStr::from_os_str_bytes_unchecked(&self.path.as_os_str_bytes()[self.index..]) }
     }
 }
 
@@ -173,7 +162,7 @@ fn parse_drive(path: &OsStr) -> Option<u8> {
         drive.is_ascii_alphabetic()
     }
 
-    match path.bytes() {
+    match path.as_os_str_bytes() {
         [drive, b':', ..] if is_valid_drive_letter(drive) => Some(drive.to_ascii_uppercase()),
         _ => None,
     }
@@ -182,7 +171,7 @@ fn parse_drive(path: &OsStr) -> Option<u8> {
 // Parses a drive prefix exactly, e.g. "C:"
 fn parse_drive_exact(path: &OsStr) -> Option<u8> {
     // only parse two bytes: the drive letter and the drive separator
-    if path.bytes().get(2).map(|&x| is_sep_byte(x)).unwrap_or(true) {
+    if path.as_os_str_bytes().get(2).map(|&x| is_sep_byte(x)).unwrap_or(true) {
         parse_drive(path)
     } else {
         None
@@ -196,21 +185,26 @@ fn parse_drive_exact(path: &OsStr) -> Option<u8> {
 fn parse_next_component(path: &OsStr, verbatim: bool) -> (&OsStr, &OsStr) {
     let separator = if verbatim { is_verbatim_sep } else { is_sep_byte };
 
-    match path.bytes().iter().position(|&x| separator(x)) {
+    match path.as_os_str_bytes().iter().position(|&x| separator(x)) {
         Some(separator_start) => {
             let separator_end = separator_start + 1;
 
-            let component = &path.bytes()[..separator_start];
+            let component = &path.as_os_str_bytes()[..separator_start];
 
             // Panic safe
             // The max `separator_end` is `bytes.len()` and `bytes[bytes.len()..]` is a valid index.
-            let path = &path.bytes()[separator_end..];
+            let path = &path.as_os_str_bytes()[separator_end..];
 
             // SAFETY: `path` is a valid wtf8 encoded slice and each of the separators ('/', '\')
             // is encoded in a single byte, therefore `bytes[separator_start]` and
             // `bytes[separator_end]` must be code point boundaries and thus
             // `bytes[..separator_start]` and `bytes[separator_end..]` are valid wtf8 slices.
-            unsafe { (bytes_as_os_str(component), bytes_as_os_str(path)) }
+            unsafe {
+                (
+                    OsStr::from_os_str_bytes_unchecked(component),
+                    OsStr::from_os_str_bytes_unchecked(path),
+                )
+            }
         }
         None => (path, OsStr::new("")),
     }
@@ -329,7 +323,7 @@ pub(crate) fn absolute(path: &Path) -> io::Result<PathBuf> {
     // Verbatim paths should not be modified.
     if prefix.map(|x| x.is_verbatim()).unwrap_or(false) {
         // NULs in verbatim paths are rejected for consistency.
-        if path.bytes().contains(&0) {
+        if path.as_os_str_bytes().contains(&0) {
             return Err(io::const_io_error!(
                 io::ErrorKind::InvalidInput,
                 "strings passed to WinAPI cannot contain NULs",
diff --git a/library/std/src/sys/windows/process.rs b/library/std/src/sys/windows/process.rs
index df3667c0f..e3493cbb8 100644
--- a/library/std/src/sys/windows/process.rs
+++ b/library/std/src/sys/windows/process.rs
@@ -395,7 +395,7 @@ fn resolve_exe<'a>(
     // Test if the file name has the `exe` extension.
     // This does a case-insensitive `ends_with`.
     let has_exe_suffix = if exe_path.len() >= EXE_SUFFIX.len() {
-        exe_path.bytes()[exe_path.len() - EXE_SUFFIX.len()..]
+        exe_path.as_os_str_bytes()[exe_path.len() - EXE_SUFFIX.len()..]
             .eq_ignore_ascii_case(EXE_SUFFIX.as_bytes())
     } else {
         false
@@ -425,7 +425,7 @@ fn resolve_exe<'a>(
         // From the `CreateProcessW` docs:
         // > If the file name does not contain an extension, .exe is appended.
         // Note that this rule only applies when searching paths.
-        let has_extension = exe_path.bytes().contains(&b'.');
+        let has_extension = exe_path.as_os_str_bytes().contains(&b'.');
 
         // Search the directories given by `search_paths`.
         let result = search_paths(parent_paths, child_paths, |mut path| {
@@ -595,7 +595,16 @@ pub struct Process {
 
 impl Process {
     pub fn kill(&mut self) -> io::Result<()> {
-        cvt(unsafe { c::TerminateProcess(self.handle.as_raw_handle(), 1) })?;
+        let result = unsafe { c::TerminateProcess(self.handle.as_raw_handle(), 1) };
+        if result == c::FALSE {
+            let error = unsafe { c::GetLastError() };
+            // TerminateProcess returns ERROR_ACCESS_DENIED if the process has already been
+            // terminated (by us, or for any other reason). So check if the process was actually
+            // terminated, and if so, do not return an error.
+            if error != c::ERROR_ACCESS_DENIED || self.try_wait().is_err() {
+                return Err(crate::io::Error::from_raw_os_error(error as i32));
+            }
+        }
         Ok(())
     }
 
diff --git a/library/std/src/sys/windows/rand.rs b/library/std/src/sys/windows/rand.rs
index bca4e38d9..5d8fd1378 100644
--- a/library/std/src/sys/windows/rand.rs
+++ b/library/std/src/sys/windows/rand.rs
@@ -1,5 +1,3 @@
-use crate::ffi::c_void;
-use crate::io;
 use crate::mem;
 use crate::ptr;
 use crate::sys::c;
@@ -25,6 +23,9 @@ pub fn hashmap_random_keys() -> (u64, u64) {
 #[cfg(not(target_vendor = "uwp"))]
 #[inline(never)]
 fn fallback_rng() -> (u64, u64) {
+    use crate::ffi::c_void;
+    use crate::io;
+
     let mut v = (0, 0);
     let ret = unsafe {
         c::RtlGenRandom(&mut v as *mut _ as *mut c_void, mem::size_of_val(&v) as c::ULONG)
diff --git a/library/std/src/sys/windows/stdio.rs b/library/std/src/sys/windows/stdio.rs
index 2e3e0859d..3fcaaa508 100644
--- a/library/std/src/sys/windows/stdio.rs
+++ b/library/std/src/sys/windows/stdio.rs
@@ -11,6 +11,9 @@ use crate::sys::cvt;
 use crate::sys::handle::Handle;
 use core::str::utf8_char_width;
 
+#[cfg(test)]
+mod tests;
+
 // Don't cache handles but get them fresh for every read/write. This allows us to track changes to
 // the value over time (such as if a process calls `SetStdHandle` while it's running). See #40490.
 pub struct Stdin {
@@ -383,6 +386,10 @@ fn utf16_to_utf8(utf16: &[u16], utf8: &mut [u8]) -> io::Result<usize> {
     debug_assert!(utf16.len() <= c::c_int::MAX as usize);
     debug_assert!(utf8.len() <= c::c_int::MAX as usize);
 
+    if utf16.is_empty() {
+        return Ok(0);
+    }
+
     let result = unsafe {
         c::WideCharToMultiByte(
             c::CP_UTF8,              // CodePage
diff --git a/library/std/src/sys/windows/stdio/tests.rs b/library/std/src/sys/windows/stdio/tests.rs
new file mode 100644
index 000000000..1e53e0bee
--- /dev/null
+++ b/library/std/src/sys/windows/stdio/tests.rs
@@ -0,0 +1,6 @@
+use super::utf16_to_utf8;
+
+#[test]
+fn zero_size_read() {
+    assert_eq!(utf16_to_utf8(&[], &mut []).unwrap(), 0);
+}