1 files changed, 770 insertions, 0 deletions
diff --git a/vendor/rustix/src/imp/linux_raw/conv.rs b/vendor/rustix/src/imp/linux_raw/conv.rs
new file mode 100644
index 000000000..c80ad58cc
--- /dev/null
+++ b/vendor/rustix/src/imp/linux_raw/conv.rs
@@ -0,0 +1,770 @@
+//! Convert values to [`ArgReg`] and from [`RetReg`].
+//!
+//! System call arguments and return values are all communicated with inline
+//! asm and FFI as `*mut Opaque`. To protect these raw pointers from escaping
+//! or being accidentally misused as they travel through the code, we wrap
+//! them in [`ArgReg`] and [`RetReg`] structs. This file provides `From`
+//! implementations and explicit conversion functions for converting values
+//! into and out of these wrapper structs.
+//!
+//! # Safety
+//!
+//! Some of this code is `unsafe` in order to work with raw file descriptors,
+//! and some is `unsafe` to interpret the values in a `RetReg`.
+#![allow(unsafe_code)]
+
+use super::c;
+use super::fd::{AsRawFd, BorrowedFd, FromRawFd, RawFd};
+#[cfg(not(debug_assertions))]
+use super::io::errno::decode_usize_infallible;
+#[cfg(feature = "runtime")]
+use super::io::errno::try_decode_error;
+#[cfg(target_pointer_width = "64")]
+use super::io::errno::try_decode_u64;
+use super::io::errno::{
+    try_decode_c_int, try_decode_c_uint, try_decode_raw_fd, try_decode_usize, try_decode_void,
+    try_decode_void_star,
+};
+use super::reg::{raw_arg, ArgNumber, ArgReg, RetReg, R0};
+#[cfg(any(feature = "thread", feature = "time", target_arch = "x86"))]
+use super::time::types::ClockId;
+#[cfg(feature = "time")]
+use super::time::types::TimerfdClockId;
+use crate::ffi::CStr;
+use crate::fs::{FileType, Mode, OFlags};
+use crate::io::{self, OwnedFd};
+use crate::process::{Pid, Resource, Signal};
+use crate::utils::{as_mut_ptr, as_ptr};
+use core::mem::MaybeUninit;
+use core::ptr::null_mut;
+#[cfg(any(feature = "thread", feature = "time", target_arch = "x86"))]
+use linux_raw_sys::general::__kernel_clockid_t;
+#[cfg(target_pointer_width = "64")]
+use linux_raw_sys::general::__kernel_loff_t;
+#[cfg(feature = "net")]
+use linux_raw_sys::general::socklen_t;
+#[cfg(target_pointer_width = "32")]
+use linux_raw_sys::general::O_LARGEFILE;
+
+/// Convert `SYS_*` constants for socketcall.
+#[cfg(target_arch = "x86")]
+#[inline]
+pub(super) fn x86_sys<'a, Num: ArgNumber>(sys: u32) -> ArgReg<'a, Num> {
+    pass_usize(sys as usize)
+}
+
+/// Pass the "low" half of the endian-specific memory encoding of a `u64`, for
+/// 32-bit architectures.
+#[cfg(target_pointer_width = "32")]
+#[inline]
+pub(super) fn lo<'a, Num: ArgNumber>(x: u64) -> ArgReg<'a, Num> {
+    #[cfg(target_endian = "little")]
+    let x = x >> 32;
+    #[cfg(target_endian = "big")]
+    let x = x & 0xffff_ffff;
+
+    pass_usize(x as usize)
+}
+
+/// Pass the "high" half of the endian-specific memory encoding of a `u64`, for
+/// 32-bit architectures.
+#[cfg(target_pointer_width = "32")]
+#[inline]
+pub(super) fn hi<'a, Num: ArgNumber>(x: u64) -> ArgReg<'a, Num> {
+    #[cfg(target_endian = "little")]
+    let x = x & 0xffff_ffff;
+    #[cfg(target_endian = "big")]
+    let x = x >> 32;
+
+    pass_usize(x as usize)
+}
+
+/// Pass a zero, or null, argument.
+#[inline]
+pub(super) fn zero<'a, Num: ArgNumber>() -> ArgReg<'a, Num> {
+    raw_arg(null_mut())
+}
+
+/// Pass the `mem::size_of` of a type.
+#[inline]
+pub(super) fn size_of<'a, T: Sized, Num: ArgNumber>() -> ArgReg<'a, Num> {
+    pass_usize(core::mem::size_of::<T>())
+}
+
+/// Pass an arbitrary `usize` value.
+///
+/// For passing pointers, use `void_star` or other functions which take a raw
+/// pointer instead of casting to `usize`, so that provenance is preserved.
+#[inline]
+pub(super) fn pass_usize<'a, Num: ArgNumber>(t: usize) -> ArgReg<'a, Num> {
+    raw_arg(t as *mut _)
+}
+
+impl<'a, Num: ArgNumber, T> From<*mut T> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(c: *mut T) -> ArgReg<'a, Num> {
+        raw_arg(c.cast())
+    }
+}
+
+impl<'a, Num: ArgNumber, T> From<*const T> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(c: *const T) -> ArgReg<'a, Num> {
+        let mut_ptr = c as *mut T;
+        raw_arg(mut_ptr.cast())
+    }
+}
+
+impl<'a, Num: ArgNumber> From<&'a CStr> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(c: &'a CStr) -> Self {
+        let mut_ptr = c.as_ptr() as *mut u8;
+        raw_arg(mut_ptr.cast())
+    }
+}
+
+impl<'a, Num: ArgNumber> From<Option<&'a CStr>> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(t: Option<&'a CStr>) -> Self {
+        raw_arg(match t {
+            Some(s) => {
+                let mut_ptr = s.as_ptr() as *mut u8;
+                mut_ptr.cast()
+            }
+            None => null_mut(),
+        })
+    }
+}
+
+/// Pass a borrowed file-descriptor argument.
+impl<'a, Num: ArgNumber> From<BorrowedFd<'a>> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(fd: BorrowedFd<'a>) -> Self {
+        // Safety: `BorrowedFd` ensures that the file descriptor is valid, and the
+        // lifetime parameter on the resulting `ArgReg` ensures that the result is
+        // bounded by the `BorrowedFd`'s lifetime.
+        unsafe { raw_fd(fd.as_raw_fd()) }
+    }
+}
+
+/// Pass a raw file-descriptor argument. Most users should use [`ArgReg::from`]
+/// instead, to preserve I/O safety as long as possible.
+///
+/// # Safety
+///
+/// `fd` must be a valid open file descriptor.
+#[inline]
+pub(super) unsafe fn raw_fd<'a, Num: ArgNumber>(fd: RawFd) -> ArgReg<'a, Num> {
+    // Use `no_fd` when passing `-1` is intended.
+    debug_assert!(fd == crate::fs::cwd().as_raw_fd() || fd >= 0);
+
+    // Don't pass the `io_uring_register_files_skip` sentry value this way.
+    #[cfg(feature = "io_uring")]
+    debug_assert_ne!(
+        fd,
+        crate::io_uring::io_uring_register_files_skip().as_raw_fd()
+    );
+
+    // Linux doesn't look at the high bits beyond the `c_int`, so use
+    // zero-extension rather than sign-extension because it's a smaller
+    // instruction.
+    let fd: c::c_int = fd;
+    pass_usize(fd as c::c_uint as usize)
+}
+
+/// Deliberately pass `-1` to a file-descriptor argument, for system calls
+/// like `mmap` where this indicates the argument is omitted.
+#[inline]
+pub(super) fn no_fd<'a, Num: ArgNumber>() -> ArgReg<'a, Num> {
+    pass_usize(!0_usize)
+}
+
+#[inline]
+pub(super) fn slice_just_addr<T: Sized, Num: ArgNumber>(v: &[T]) -> ArgReg<Num> {
+    let mut_ptr = v.as_ptr() as *mut T;
+    raw_arg(mut_ptr.cast())
+}
+
+#[inline]
+pub(super) fn slice<T: Sized, Num0: ArgNumber, Num1: ArgNumber>(
+    v: &[T],
+) -> (ArgReg<Num0>, ArgReg<Num1>) {
+    (slice_just_addr(v), pass_usize(v.len()))
+}
+
+#[inline]
+pub(super) fn slice_mut<T: Sized, Num0: ArgNumber, Num1: ArgNumber>(
+    v: &mut [T],
+) -> (ArgReg<Num0>, ArgReg<Num1>) {
+    (raw_arg(v.as_mut_ptr().cast()), pass_usize(v.len()))
+}
+
+#[inline]
+pub(super) fn by_ref<T: Sized, Num: ArgNumber>(t: &T) -> ArgReg<Num> {
+    let mut_ptr = as_ptr(t) as *mut T;
+    raw_arg(mut_ptr.cast())
+}
+
+#[inline]
+pub(super) fn by_mut<T: Sized, Num: ArgNumber>(t: &mut T) -> ArgReg<Num> {
+    raw_arg(as_mut_ptr(t).cast())
+}
+
+/// Convert an optional mutable reference into a `usize` for passing to a
+/// syscall.
+#[inline]
+pub(super) fn opt_mut<T: Sized, Num: ArgNumber>(t: Option<&mut T>) -> ArgReg<Num> {
+    // This optimizes into the equivalent of `transmute(t)`, and has the
+    // advantage of not requiring `unsafe`.
+    match t {
+        Some(t) => by_mut(t),
+        None => raw_arg(null_mut()),
+    }
+}
+
+/// Convert an optional immutable reference into a `usize` for passing to a
+/// syscall.
+#[cfg(any(target_arch = "aarch64", target_arch = "riscv64"))]
+#[inline]
+pub(super) fn opt_ref<'a, T: Sized, Num: ArgNumber>(t: Option<&'a T>) -> ArgReg<'a, Num> {
+    // This optimizes into the equivalent of `transmute(t)`, and has the
+    // advantage of not requiring `unsafe`.
+    match t {
+        Some(t) => by_ref(t),
+        None => raw_arg(null_mut()),
+    }
+}
+
+/// Convert a `c_int` into an `ArgReg`.
+///
+/// Be sure to use `raw_fd` to pass `RawFd` values.
+#[inline]
+pub(super) fn c_int<'a, Num: ArgNumber>(i: c::c_int) -> ArgReg<'a, Num> {
+    pass_usize(i as usize)
+}
+
+/// Convert a `c_uint` into an `ArgReg`.
+#[inline]
+pub(super) fn c_uint<'a, Num: ArgNumber>(i: c::c_uint) -> ArgReg<'a, Num> {
+    pass_usize(i as usize)
+}
+
+#[cfg(target_pointer_width = "64")]
+#[inline]
+pub(super) fn loff_t<'a, Num: ArgNumber>(i: __kernel_loff_t) -> ArgReg<'a, Num> {
+    pass_usize(i as usize)
+}
+
+#[cfg(target_pointer_width = "64")]
+#[inline]
+pub(super) fn loff_t_from_u64<'a, Num: ArgNumber>(i: u64) -> ArgReg<'a, Num> {
+    // `loff_t` is signed, but syscalls which expect `loff_t` return `EINVAL`
+    // if it's outside the signed `i64` range, so we can silently cast.
+    pass_usize(i as usize)
+}
+
+#[cfg(any(feature = "thread", feature = "time", target_arch = "x86"))]
+impl<'a, Num: ArgNumber> From<ClockId> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(i: ClockId) -> Self {
+        pass_usize(i as __kernel_clockid_t as usize)
+    }
+}
+
+#[cfg(feature = "time")]
+impl<'a, Num: ArgNumber> From<TimerfdClockId> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(i: TimerfdClockId) -> Self {
+        pass_usize(i as __kernel_clockid_t as usize)
+    }
+}
+
+#[cfg(feature = "net")]
+#[inline]
+pub(super) fn socklen_t<'a, Num: ArgNumber>(i: socklen_t) -> ArgReg<'a, Num> {
+    pass_usize(i as usize)
+}
+
+impl<'a, Num: ArgNumber> From<Mode> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(mode: Mode) -> Self {
+        pass_usize(mode.bits() as usize)
+    }
+}
+
+impl<'a, Num: ArgNumber> From<(Mode, FileType)> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(pair: (Mode, FileType)) -> Self {
+        pass_usize(pair.0.as_raw_mode() as usize | pair.1.as_raw_mode() as usize)
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::fs::AtFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::fs::AtFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::fs::MemfdFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::fs::MemfdFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::fs::RenameFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::fs::RenameFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::fs::StatxFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::fs::StatxFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::fs::FdFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::fs::FdFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::io::PipeFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::io::PipeFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::io::DupFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::io::DupFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::io::ReadWriteFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::io::ReadWriteFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::io::EventfdFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::io::EventfdFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::io::epoll::CreateFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::io::epoll::CreateFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(any(feature = "mm", feature = "time", target_arch = "x86"))] // vdso.rs uses `madvise`
+impl<'a, Num: ArgNumber> From<crate::imp::mm::types::ProtFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::imp::mm::types::ProtFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(any(feature = "mm", feature = "time", target_arch = "x86"))] // vdso.rs uses `madvise`
+impl<'a, Num: ArgNumber> From<crate::imp::mm::types::MsyncFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::imp::mm::types::MsyncFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(any(feature = "mm", feature = "time", target_arch = "x86"))] // vdso.rs uses `madvise`
+impl<'a, Num: ArgNumber> From<crate::imp::mm::types::MremapFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::imp::mm::types::MremapFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(any(feature = "mm", feature = "time", target_arch = "x86"))] // vdso.rs uses `madvise`
+impl<'a, Num: ArgNumber> From<crate::imp::mm::types::MlockFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::imp::mm::types::MlockFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(any(feature = "mm", feature = "time", target_arch = "x86"))] // vdso.rs uses `madvise`
+impl<'a, Num: ArgNumber> From<crate::imp::mm::types::MapFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::imp::mm::types::MapFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(any(feature = "mm", feature = "time", target_arch = "x86"))] // vdso.rs uses `madvise`
+impl<'a, Num: ArgNumber> From<crate::imp::mm::types::MprotectFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::imp::mm::types::MprotectFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(any(feature = "mm", feature = "time", target_arch = "x86"))] // vdso.rs uses `madvise`
+impl<'a, Num: ArgNumber> From<crate::imp::mm::types::UserfaultfdFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::imp::mm::types::UserfaultfdFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::imp::process::types::MembarrierCommand> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(cmd: crate::imp::process::types::MembarrierCommand) -> Self {
+        c_uint(cmd as u32)
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::process::Cpuid> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(cpuid: crate::process::Cpuid) -> Self {
+        c_uint(cpuid.as_raw())
+    }
+}
+
+#[cfg(target_pointer_width = "64")]
+#[inline]
+pub(super) fn dev_t<'a, Num: ArgNumber>(dev: u64) -> ArgReg<'a, Num> {
+    pass_usize(dev as usize)
+}
+
+#[cfg(target_pointer_width = "32")]
+#[inline]
+pub(super) fn dev_t<'a, Num: ArgNumber>(dev: u64) -> io::Result<ArgReg<'a, Num>> {
+    use core::convert::TryInto;
+    Ok(pass_usize(dev.try_into().map_err(|_err| io::Errno::INVAL)?))
+}
+
+#[cfg(target_pointer_width = "32")]
+#[inline]
+fn oflags_bits(oflags: OFlags) -> c::c_uint {
+    let mut bits = oflags.bits();
+    // Add `O_LARGEFILE`, unless `O_PATH` is set, as Linux returns `EINVAL`
+    // when both are set.
+    if !oflags.contains(OFlags::PATH) {
+        bits |= O_LARGEFILE;
+    }
+    bits
+}
+
+#[cfg(target_pointer_width = "64")]
+#[inline]
+const fn oflags_bits(oflags: OFlags) -> c::c_uint {
+    oflags.bits()
+}
+
+impl<'a, Num: ArgNumber> From<OFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(oflags: OFlags) -> Self {
+        pass_usize(oflags_bits(oflags) as usize)
+    }
+}
+
+/// Convert an `OFlags` into a `u64` for use in the `open_how` struct.
+#[inline]
+pub(super) fn oflags_for_open_how(oflags: OFlags) -> u64 {
+    u64::from(oflags_bits(oflags))
+}
+
+impl<'a, Num: ArgNumber> From<crate::fs::FallocateFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::fs::FallocateFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+/// Convert a `Resource` into a syscall argument.
+impl<'a, Num: ArgNumber> From<Resource> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(resource: Resource) -> Self {
+        c_uint(resource as c::c_uint)
+    }
+}
+
+impl<'a, Num: ArgNumber> From<Pid> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(pid: Pid) -> Self {
+        pass_usize(pid.as_raw_nonzero().get() as usize)
+    }
+}
+
+#[inline]
+pub(super) fn negative_pid<'a, Num: ArgNumber>(pid: Pid) -> ArgReg<'a, Num> {
+    pass_usize(pid.as_raw_nonzero().get().wrapping_neg() as usize)
+}
+
+impl<'a, Num: ArgNumber> From<Signal> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(sig: Signal) -> Self {
+        pass_usize(sig as usize)
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::fs::Advice> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(advice: crate::fs::Advice) -> Self {
+        c_uint(advice as c::c_uint)
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::fs::SealFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::fs::SealFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(feature = "io_uring")]
+impl<'a, Num: ArgNumber> From<crate::io_uring::IoringEnterFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::io_uring::IoringEnterFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(feature = "time")]
+impl<'a, Num: ArgNumber> From<crate::time::TimerfdFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::time::TimerfdFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(feature = "time")]
+impl<'a, Num: ArgNumber> From<crate::time::TimerfdTimerFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::time::TimerfdTimerFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(feature = "rand")]
+impl<'a, Num: ArgNumber> From<crate::rand::GetRandomFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::rand::GetRandomFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(feature = "net")]
+impl<'a, Num: ArgNumber> From<crate::net::RecvFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::net::RecvFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(feature = "net")]
+impl<'a, Num: ArgNumber> From<crate::net::SendFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::net::SendFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(feature = "net")]
+impl<'a, Num: ArgNumber> From<crate::net::AcceptFlags> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(flags: crate::net::AcceptFlags) -> Self {
+        c_uint(flags.bits())
+    }
+}
+
+#[cfg(feature = "net")]
+impl<'a, Num: ArgNumber> From<crate::net::AddressFamily> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(family: crate::net::AddressFamily) -> Self {
+        c_uint(family.0.into())
+    }
+}
+
+#[cfg(feature = "net")]
+impl<'a, Num: ArgNumber> From<(crate::net::SocketType, crate::net::SocketFlags)>
+    for ArgReg<'a, Num>
+{
+    #[inline]
+    fn from(pair: (crate::net::SocketType, crate::net::SocketFlags)) -> Self {
+        c_uint(pair.0 .0 | pair.1.bits())
+    }
+}
+
+#[cfg(feature = "thread")]
+impl<'a, Num: ArgNumber> From<(crate::thread::FutexOperation, crate::thread::FutexFlags)>
+    for ArgReg<'a, Num>
+{
+    #[inline]
+    fn from(pair: (crate::thread::FutexOperation, crate::thread::FutexFlags)) -> Self {
+        c_uint(pair.0 as u32 | pair.1.bits())
+    }
+}
+
+impl<'a, Num: ArgNumber> From<crate::fs::Access> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(access: crate::fs::Access) -> Self {
+        c_uint(access.bits())
+    }
+}
+
+#[cfg(feature = "net")]
+impl<'a, Num: ArgNumber> From<crate::net::SocketType> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(type_: crate::net::SocketType) -> Self {
+        c_uint(type_.0)
+    }
+}
+
+#[cfg(feature = "net")]
+impl<'a, Num: ArgNumber> From<crate::net::Protocol> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(protocol: crate::net::Protocol) -> Self {
+        c_uint(protocol.0)
+    }
+}
+
+impl<'a, Num: ArgNumber, T> From<&'a mut MaybeUninit<T>> for ArgReg<'a, Num> {
+    #[inline]
+    fn from(t: &'a mut MaybeUninit<T>) -> Self {
+        raw_arg(t.as_mut_ptr().cast())
+    }
+}
+
+/// Convert a `usize` returned from a syscall that effectively returns `()` on
+/// success.
+///
+/// # Safety
+///
+/// The caller must ensure that this is the return value of a syscall which
+/// just returns 0 on success.
+#[inline]
+pub(super) unsafe fn ret(raw: RetReg<R0>) -> io::Result<()> {
+    try_decode_void(raw)
+}
+
+/// Convert a `usize` returned from a syscall that doesn't return on success.
+///
+/// # Safety
+///
+/// The caller must ensure that this is the return value of a syscall which
+/// doesn't return on success.
+#[cfg(feature = "runtime")]
+#[inline]
+pub(super) unsafe fn ret_error(raw: RetReg<R0>) -> io::Errno {
+    try_decode_error(raw)
+}
+
+/// Convert a `usize` returned from a syscall that effectively always returns
+/// `()`.
+///
+/// # Safety
+///
+/// The caller must ensure that this is the return value of a syscall which
+/// always returns `()`.
+#[inline]
+pub(super) unsafe fn ret_infallible(raw: RetReg<R0>) {
+    #[cfg(debug_assertions)]
+    {
+        try_decode_void(raw).unwrap()
+    }
+    #[cfg(not(debug_assertions))]
+    drop(raw);
+}
+
+/// Convert a `usize` returned from a syscall that effectively returns a
+/// `c_int` on success.
+#[inline]
+pub(super) fn ret_c_int(raw: RetReg<R0>) -> io::Result<c::c_int> {
+    try_decode_c_int(raw)
+}
+
+/// Convert a `usize` returned from a syscall that effectively returns a
+/// `c_uint` on success.
+#[inline]
+pub(super) fn ret_c_uint(raw: RetReg<R0>) -> io::Result<c::c_uint> {
+    try_decode_c_uint(raw)
+}
+
+/// Convert a `usize` returned from a syscall that effectively returns a `u64`
+/// on success.
+#[cfg(target_pointer_width = "64")]
+#[inline]
+pub(super) fn ret_u64(raw: RetReg<R0>) -> io::Result<u64> {
+    try_decode_u64(raw)
+}
+
+/// Convert a `usize` returned from a syscall that effectively returns a
+/// `usize` on success.
+#[inline]
+pub(super) fn ret_usize(raw: RetReg<R0>) -> io::Result<usize> {
+    try_decode_usize(raw)
+}
+
+/// Convert a `usize` returned from a syscall that effectively always
+/// returns a `usize`.
+///
+/// # Safety
+///
+/// This function must only be used with return values from infallible
+/// syscalls.
+#[inline]
+pub(super) unsafe fn ret_usize_infallible(raw: RetReg<R0>) -> usize {
+    #[cfg(debug_assertions)]
+    {
+        try_decode_usize(raw).unwrap()
+    }
+    #[cfg(not(debug_assertions))]
+    {
+        decode_usize_infallible(raw)
+    }
+}
+
+/// Convert a `usize` returned from a syscall that effectively returns an
+/// `OwnedFd` on success.
+///
+/// # Safety
+///
+/// The caller must ensure that this is the return value of a syscall which
+/// returns an owned file descriptor.
+#[inline]
+pub(super) unsafe fn ret_owned_fd(raw: RetReg<R0>) -> io::Result<OwnedFd> {
+    let raw_fd = try_decode_raw_fd(raw)?;
+    Ok(OwnedFd::from(crate::imp::fd::OwnedFd::from_raw_fd(raw_fd)))
+}
+
+/// Convert the return value of `dup2` and `dup3`.
+///
+/// When these functions succeed, they return the same value as their second
+/// argument, so we don't construct a new `OwnedFd`.
+///
+/// # Safety
+///
+/// The caller must ensure that this is the return value of a syscall which
+/// returns a file descriptor.
+#[inline]
+pub(super) unsafe fn ret_discarded_fd(raw: RetReg<R0>) -> io::Result<()> {
+    let _raw_fd = try_decode_raw_fd(raw)?;
+    Ok(())
+}
+
+/// Convert a `usize` returned from a syscall that effectively returns a
+/// `*mut c_void` on success.
+#[inline]
+pub(super) fn ret_void_star(raw: RetReg<R0>) -> io::Result<*mut c::c_void> {
+    try_decode_void_star(raw)
+}