vendor/rustix-0.37.6/src/backend/linux_raw/process/syscalls.rs - toolchain/rustc - Git at Google

 //! linux_raw syscalls supporting `rustix::process`.
 //!
 //! # Safety
 //!
 //! See the `rustix::backend` module documentation for details.
 #![allow(unsafe_code)]
 #![allow(clippy::undocumented_unsafe_blocks)]

 use super::super::c;
 use super::super::conv::{
     by_mut, by_ref, c_int, c_uint, negative_pid, pass_usize, ret, ret_c_int, ret_c_uint,
     ret_infallible, ret_usize, ret_usize_infallible, size_of, slice_just_addr, slice_mut, zero,
 };
 use super::types::{RawCpuSet, RawUname};
 use crate::backend::conv::ret_owned_fd;
 use crate::fd::{AsRawFd, BorrowedFd, OwnedFd};
 use crate::ffi::CStr;
 use crate::io;
 use crate::process::{
     Cpuid, Gid, MembarrierCommand, MembarrierQuery, Pid, PidfdFlags, RawNonZeroPid, RawPid,
     Resource, Rlimit, Signal, Uid, WaitId, WaitOptions, WaitStatus, WaitidOptions, WaitidStatus,
 };
 use core::convert::TryInto;
 use core::mem::MaybeUninit;
 use core::num::NonZeroU32;
 use core::ptr::{null, null_mut};
 use linux_raw_sys::general::{
     __kernel_gid_t, __kernel_pid_t, __kernel_uid_t, membarrier_cmd, membarrier_cmd_flag, rlimit,
     rlimit64, PRIO_PGRP, PRIO_PROCESS, PRIO_USER, RLIM64_INFINITY, RLIM_INFINITY,
 };
 #[cfg(not(target_os = "wasi"))]
 #[cfg(feature = "fs")]
 use {super::super::conv::ret_c_uint_infallible, crate::fs::Mode};

 #[inline]
 pub(crate) fn chdir(filename: &CStr) -> io::Result<()> {
     unsafe { ret(syscall_readonly!(__NR_chdir, filename)) }
 }

 #[inline]
 pub(crate) fn fchdir(fd: BorrowedFd<'_>) -> io::Result<()> {
     unsafe { ret(syscall_readonly!(__NR_fchdir, fd)) }
 }

 #[inline]
 pub(crate) fn getcwd(buf: &mut [u8]) -> io::Result<usize> {
     let (buf_addr_mut, buf_len) = slice_mut(buf);
     unsafe { ret_usize(syscall!(__NR_getcwd, buf_addr_mut, buf_len)) }
 }

 #[inline]
 pub(crate) fn membarrier_query() -> MembarrierQuery {
     unsafe {
         match ret_c_uint(syscall!(
             __NR_membarrier,
             c_int(membarrier_cmd::MEMBARRIER_CMD_QUERY as _),
             c_uint(0)
         )) {
             Ok(query) => {
                 // SAFETY: The safety of `from_bits_unchecked` is discussed
                 // [here]. Our "source of truth" is Linux, and here, the
                 // `query` value is coming from Linux, so we know it only
                 // contains "source of truth" valid bits.
                 //
                 // [here]: https://github.com/bitflags/bitflags/pull/207#issuecomment-671668662
                 MembarrierQuery::from_bits_unchecked(query)
             }
             Err(_) => MembarrierQuery::empty(),
         }
     }
 }

 #[inline]
 pub(crate) fn membarrier(cmd: MembarrierCommand) -> io::Result<()> {
     unsafe { ret(syscall!(__NR_membarrier, cmd, c_uint(0))) }
 }

 #[inline]
 pub(crate) fn membarrier_cpu(cmd: MembarrierCommand, cpu: Cpuid) -> io::Result<()> {
     unsafe {
         ret(syscall!(
             __NR_membarrier,
             cmd,
             c_uint(membarrier_cmd_flag::MEMBARRIER_CMD_FLAG_CPU as _),
             cpu
         ))
     }
 }

 #[inline]
 pub(crate) fn getpid() -> Pid {
     unsafe {
         let pid: i32 = ret_usize_infallible(syscall_readonly!(__NR_getpid)) as __kernel_pid_t;
         debug_assert!(pid > 0);
         Pid::from_raw_nonzero(RawNonZeroPid::new_unchecked(pid as u32))
     }
 }

 #[inline]
 pub(crate) fn getppid() -> Option<Pid> {
     unsafe {
         let ppid: i32 = ret_usize_infallible(syscall_readonly!(__NR_getppid)) as __kernel_pid_t;
         Pid::from_raw(ppid as u32)
     }
 }

 #[inline]
 pub(crate) fn getpgid(pid: Option<Pid>) -> io::Result<Pid> {
     unsafe {
         let pgid: i32 =
             ret_usize(syscall_readonly!(__NR_getpgid, c_uint(Pid::as_raw(pid))))? as __kernel_pid_t;
         Ok(Pid::from_raw_nonzero(NonZeroU32::new_unchecked(
             pgid as u32,
         )))
     }
 }

 #[inline]
 pub(crate) fn getpgrp() -> Pid {
     // Use the `getpgrp` syscall if available.
     #[cfg(not(any(target_arch = "aarch64", target_arch = "riscv64")))]
     unsafe {
         let pgid: i32 = ret_usize_infallible(syscall_readonly!(__NR_getpgrp)) as __kernel_pid_t;
         debug_assert!(pgid > 0);
         Pid::from_raw_nonzero(RawNonZeroPid::new_unchecked(pgid as u32))
     }

     // Otherwise use `getpgrp` and pass it zero.
     #[cfg(any(target_arch = "aarch64", target_arch = "riscv64"))]
     unsafe {
         let pgid: i32 =
             ret_usize_infallible(syscall_readonly!(__NR_getpgid, c_uint(0))) as __kernel_pid_t;
         debug_assert!(pgid > 0);
         Pid::from_raw_nonzero(RawNonZeroPid::new_unchecked(pgid as u32))
     }
 }

 #[inline]
 pub(crate) fn getgid() -> Gid {
     #[cfg(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm"))]
     unsafe {
         let gid: i32 =
             (ret_usize_infallible(syscall_readonly!(__NR_getgid32)) as __kernel_gid_t).into();
         Gid::from_raw(gid as u32)
     }
     #[cfg(not(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm")))]
     unsafe {
         let gid = ret_usize_infallible(syscall_readonly!(__NR_getgid)) as __kernel_gid_t;
         Gid::from_raw(gid as u32)
     }
 }

 #[inline]
 pub(crate) fn getegid() -> Gid {
     #[cfg(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm"))]
     unsafe {
         let gid: i32 =
             (ret_usize_infallible(syscall_readonly!(__NR_getegid32)) as __kernel_gid_t).into();
         Gid::from_raw(gid as u32)
     }
     #[cfg(not(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm")))]
     unsafe {
         let gid = ret_usize_infallible(syscall_readonly!(__NR_getegid)) as __kernel_gid_t;
         Gid::from_raw(gid as u32)
     }
 }

 #[inline]
 pub(crate) fn getuid() -> Uid {
     #[cfg(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm"))]
     unsafe {
         let uid = (ret_usize_infallible(syscall_readonly!(__NR_getuid32)) as __kernel_uid_t).into();
         Uid::from_raw(uid)
     }
     #[cfg(not(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm")))]
     unsafe {
         let uid = ret_usize_infallible(syscall_readonly!(__NR_getuid)) as __kernel_uid_t;
         Uid::from_raw(uid as u32)
     }
 }

 #[inline]
 pub(crate) fn geteuid() -> Uid {
     #[cfg(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm"))]
     unsafe {
         let uid: i32 =
             (ret_usize_infallible(syscall_readonly!(__NR_geteuid32)) as __kernel_uid_t).into();
         Uid::from_raw(uid as u32)
     }
     #[cfg(not(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm")))]
     unsafe {
         let uid = ret_usize_infallible(syscall_readonly!(__NR_geteuid)) as __kernel_uid_t;
         Uid::from_raw(uid as u32)
     }
 }

 #[inline]
 pub(crate) fn sched_getaffinity(pid: Option<Pid>, cpuset: &mut RawCpuSet) -> io::Result<()> {
     unsafe {
         // The raw linux syscall returns the size (in bytes) of the `cpumask_t`
         // data type that is used internally by the kernel to represent the CPU
         // set bit mask.
         let size = ret_usize(syscall!(
             __NR_sched_getaffinity,
             c_uint(Pid::as_raw(pid)),
             size_of::<RawCpuSet, _>(),
             by_mut(&mut cpuset.bits)
         ))?;
         let bytes = (cpuset as *mut RawCpuSet).cast::<u8>();
         let rest = bytes.wrapping_add(size);
         // Zero every byte in the cpuset not set by the kernel.
         rest.write_bytes(0, core::mem::size_of::<RawCpuSet>() - size);
         Ok(())
     }
 }

 #[inline]
 pub(crate) fn sched_setaffinity(pid: Option<Pid>, cpuset: &RawCpuSet) -> io::Result<()> {
     unsafe {
         ret(syscall_readonly!(
             __NR_sched_setaffinity,
             c_uint(Pid::as_raw(pid)),
             size_of::<RawCpuSet, _>(),
             slice_just_addr(&cpuset.bits)
         ))
     }
 }

 #[inline]
 pub(crate) fn sched_yield() {
     unsafe {
         // See the documentation for [`crate::process::sched_yield`] for why
         // errors are ignored.
         syscall_readonly!(__NR_sched_yield).decode_void();
     }
 }

 #[inline]
 pub(crate) fn uname() -> RawUname {
     let mut uname = MaybeUninit::<RawUname>::uninit();
     unsafe {
         ret_infallible(syscall!(__NR_uname, &mut uname));
         uname.assume_init()
     }
 }

 #[cfg(feature = "fs")]
 #[inline]
 pub(crate) fn umask(mode: Mode) -> Mode {
     unsafe {
         // TODO: Use `from_bits_retain` when we switch to bitflags 2.0.
         Mode::from_bits_truncate(ret_c_uint_infallible(syscall_readonly!(__NR_umask, mode)))
     }
 }

 #[inline]
 pub(crate) fn nice(inc: i32) -> io::Result<i32> {
     let priority = if inc > -40 && inc < 40 {
         inc + getpriority_process(None)?
     } else {
         inc
     }
     // TODO: With Rust 1.50, use `.clamp` instead of `.min` and `.max`.
     //.clamp(-20, 19);
     .min(19)
     .max(-20);
     setpriority_process(None, priority)?;
     Ok(priority)
 }

 #[inline]
 pub(crate) fn getpriority_user(uid: Uid) -> io::Result<i32> {
     unsafe {
         Ok(20
             - ret_c_int(syscall_readonly!(
                 __NR_getpriority,
                 c_uint(PRIO_USER),
                 c_uint(uid.as_raw())
             ))?)
     }
 }

 #[inline]
 pub(crate) fn getpriority_pgrp(pgid: Option<Pid>) -> io::Result<i32> {
     unsafe {
         Ok(20
             - ret_c_int(syscall_readonly!(
                 __NR_getpriority,
                 c_uint(PRIO_PGRP),
                 c_uint(Pid::as_raw(pgid))
             ))?)
     }
 }

 #[inline]
 pub(crate) fn getpriority_process(pid: Option<Pid>) -> io::Result<i32> {
     unsafe {
         Ok(20
             - ret_c_int(syscall_readonly!(
                 __NR_getpriority,
                 c_uint(PRIO_PROCESS),
                 c_uint(Pid::as_raw(pid))
             ))?)
     }
 }

 #[inline]
 pub(crate) fn setpriority_user(uid: Uid, priority: i32) -> io::Result<()> {
     unsafe {
         ret(syscall_readonly!(
             __NR_setpriority,
             c_uint(PRIO_USER),
             c_uint(uid.as_raw()),
             c_int(priority)
         ))
     }
 }

 #[inline]
 pub(crate) fn setpriority_pgrp(pgid: Option<Pid>, priority: i32) -> io::Result<()> {
     unsafe {
         ret(syscall_readonly!(
             __NR_setpriority,
             c_uint(PRIO_PGRP),
             c_uint(Pid::as_raw(pgid)),
             c_int(priority)
         ))
     }
 }

 #[inline]
 pub(crate) fn setpriority_process(pid: Option<Pid>, priority: i32) -> io::Result<()> {
     unsafe {
         ret(syscall_readonly!(
             __NR_setpriority,
             c_uint(PRIO_PROCESS),
             c_uint(Pid::as_raw(pid)),
             c_int(priority)
         ))
     }
 }

 #[inline]
 pub(crate) fn getrlimit(limit: Resource) -> Rlimit {
     let mut result = MaybeUninit::<rlimit64>::uninit();
     unsafe {
         match ret(syscall!(
             __NR_prlimit64,
             c_uint(0),
             limit,
             null::<c::c_void>(),
             &mut result
         )) {
             Ok(()) => rlimit_from_linux(result.assume_init()),
             Err(err) => {
                 debug_assert_eq!(err, io::Errno::NOSYS);
                 getrlimit_old(limit)
             }
         }
     }
 }

 /// The old 32-bit-only `getrlimit` syscall, for when we lack the new
 /// `prlimit64`.
 unsafe fn getrlimit_old(limit: Resource) -> Rlimit {
     let mut result = MaybeUninit::<rlimit>::uninit();

     // On these platforms, `__NR_getrlimit` is called `__NR_ugetrlimit`.
     #[cfg(any(
         target_arch = "arm",
         target_arch = "powerpc",
         target_arch = "powerpc64",
         target_arch = "x86",
     ))]
     {
         ret_infallible(syscall!(__NR_ugetrlimit, limit, &mut result));
     }

     // On these platforms, it's just `__NR_getrlimit`.
     #[cfg(not(any(
         target_arch = "arm",
         target_arch = "powerpc",
         target_arch = "powerpc64",
         target_arch = "x86",
     )))]
     {
         ret_infallible(syscall!(__NR_getrlimit, limit, &mut result));
     }

     rlimit_from_linux_old(result.assume_init())
 }

 #[inline]
 pub(crate) fn setrlimit(limit: Resource, new: Rlimit) -> io::Result<()> {
     unsafe {
         let lim = rlimit_to_linux(new.clone());
         match ret(syscall_readonly!(
             __NR_prlimit64,
             c_uint(0),
             limit,
             by_ref(&lim),
             null_mut::<c::c_void>()
         )) {
             Ok(()) => Ok(()),
             Err(io::Errno::NOSYS) => setrlimit_old(limit, new),
             Err(err) => Err(err),
         }
     }
 }

 /// The old 32-bit-only `setrlimit` syscall, for when we lack the new
 /// `prlimit64`.
 unsafe fn setrlimit_old(limit: Resource, new: Rlimit) -> io::Result<()> {
     let lim = rlimit_to_linux_old(new)?;
     ret(syscall_readonly!(__NR_setrlimit, limit, by_ref(&lim)))
 }

 #[inline]
 pub(crate) fn prlimit(pid: Option<Pid>, limit: Resource, new: Rlimit) -> io::Result<Rlimit> {
     let lim = rlimit_to_linux(new);
     let mut result = MaybeUninit::<rlimit64>::uninit();
     unsafe {
         match ret(syscall!(
             __NR_prlimit64,
             c_uint(Pid::as_raw(pid)),
             limit,
             by_ref(&lim),
             &mut result
         )) {
             Ok(()) => Ok(rlimit_from_linux(result.assume_init())),
             Err(err) => Err(err),
         }
     }
 }

 /// Convert a Rust [`Rlimit`] to a C `rlimit64`.
 #[inline]
 fn rlimit_from_linux(lim: rlimit64) -> Rlimit {
     let current = if lim.rlim_cur == RLIM64_INFINITY as _ {
         None
     } else {
         Some(lim.rlim_cur)
     };
     let maximum = if lim.rlim_max == RLIM64_INFINITY as _ {
         None
     } else {
         Some(lim.rlim_max)
     };
     Rlimit { current, maximum }
 }

 /// Convert a C `rlimit64` to a Rust `Rlimit`.
 #[inline]
 fn rlimit_to_linux(lim: Rlimit) -> rlimit64 {
     let rlim_cur = match lim.current {
         Some(r) => r,
         None => RLIM64_INFINITY as _,
     };
     let rlim_max = match lim.maximum {
         Some(r) => r,
         None => RLIM64_INFINITY as _,
     };
     rlimit64 { rlim_cur, rlim_max }
 }

 /// Like `rlimit_from_linux` but uses Linux's old 32-bit `rlimit`.
 #[allow(clippy::useless_conversion)]
 fn rlimit_from_linux_old(lim: rlimit) -> Rlimit {
     let current = if lim.rlim_cur == RLIM_INFINITY as _ {
         None
     } else {
         Some(lim.rlim_cur.into())
     };
     let maximum = if lim.rlim_max == RLIM_INFINITY as _ {
         None
     } else {
         Some(lim.rlim_max.into())
     };
     Rlimit { current, maximum }
 }

 /// Like `rlimit_to_linux` but uses Linux's old 32-bit `rlimit`.
 #[allow(clippy::useless_conversion)]
 fn rlimit_to_linux_old(lim: Rlimit) -> io::Result<rlimit> {
     let rlim_cur = match lim.current {
         Some(r) => r.try_into().map_err(|_e| io::Errno::INVAL)?,
         None => RLIM_INFINITY as _,
     };
     let rlim_max = match lim.maximum {
         Some(r) => r.try_into().map_err(|_e| io::Errno::INVAL)?,
         None => RLIM_INFINITY as _,
     };
     Ok(rlimit { rlim_cur, rlim_max })
 }

 #[inline]
 pub(crate) fn wait(waitopts: WaitOptions) -> io::Result<Option<(Pid, WaitStatus)>> {
     _waitpid(!0, waitopts)
 }

 #[inline]
 pub(crate) fn waitpid(
     pid: Option<Pid>,
     waitopts: WaitOptions,
 ) -> io::Result<Option<(Pid, WaitStatus)>> {
     _waitpid(Pid::as_raw(pid), waitopts)
 }

 #[inline]
 pub(crate) fn _waitpid(
     pid: RawPid,
     waitopts: WaitOptions,
 ) -> io::Result<Option<(Pid, WaitStatus)>> {
     unsafe {
         let mut status = MaybeUninit::<u32>::uninit();
         let pid = ret_c_uint(syscall!(
             __NR_wait4,
             c_int(pid as _),
             &mut status,
             c_int(waitopts.bits() as _),
             zero()
         ))?;
         Ok(RawNonZeroPid::new(pid).map(|non_zero| {
             (
                 Pid::from_raw_nonzero(non_zero),
                 WaitStatus::new(status.assume_init()),
             )
         }))
     }
 }

 #[inline]
 pub(crate) fn waitid(id: WaitId<'_>, options: WaitidOptions) -> io::Result<Option<WaitidStatus>> {
     // Get the id to wait on.
     match id {
         WaitId::All => _waitid_all(options),
         WaitId::Pid(pid) => _waitid_pid(pid, options),
         WaitId::PidFd(fd) => _waitid_pidfd(fd, options),
     }
 }

 #[inline]
 fn _waitid_all(options: WaitidOptions) -> io::Result<Option<WaitidStatus>> {
     let mut status = MaybeUninit::<c::siginfo_t>::uninit();
     unsafe {
         ret(syscall!(
             __NR_waitid,
             c_uint(c::P_ALL),
             c_uint(0),
             by_mut(&mut status),
             c_int(options.bits() as _),
             zero()
         ))?
     };

     Ok(unsafe { cvt_waitid_status(status) })
 }

 #[inline]
 fn _waitid_pid(pid: Pid, options: WaitidOptions) -> io::Result<Option<WaitidStatus>> {
     let mut status = MaybeUninit::<c::siginfo_t>::uninit();
     unsafe {
         ret(syscall!(
             __NR_waitid,
             c_uint(c::P_PID),
             c_uint(Pid::as_raw(Some(pid))),
             by_mut(&mut status),
             c_int(options.bits() as _),
             zero()
         ))?
     };

     Ok(unsafe { cvt_waitid_status(status) })
 }

 #[inline]
 fn _waitid_pidfd(fd: BorrowedFd<'_>, options: WaitidOptions) -> io::Result<Option<WaitidStatus>> {
     let mut status = MaybeUninit::<c::siginfo_t>::uninit();
     unsafe {
         ret(syscall!(
             __NR_waitid,
             c_uint(c::P_PIDFD),
             c_uint(fd.as_raw_fd() as _),
             by_mut(&mut status),
             c_int(options.bits() as _),
             zero()
         ))?
     };

     Ok(unsafe { cvt_waitid_status(status) })
 }

 /// Convert a `siginfo_t` to a `WaitidStatus`.
 ///
 /// # Safety
 ///
 /// The caller must ensure that `status` is initialized and that `waitid`
 /// returned successfully.
 #[inline]
 unsafe fn cvt_waitid_status(status: MaybeUninit<c::siginfo_t>) -> Option<WaitidStatus> {
     let status = status.assume_init();
     if status.__bindgen_anon_1.__bindgen_anon_1.si_signo == 0 {
         None
     } else {
         Some(WaitidStatus(status))
     }
 }

 #[cfg(feature = "runtime")]
 #[inline]
 pub(crate) fn exit_group(code: c::c_int) -> ! {
     unsafe { syscall_noreturn!(__NR_exit_group, c_int(code)) }
 }

 #[inline]
 pub(crate) fn setsid() -> io::Result<Pid> {
     unsafe {
         let pid = ret_usize(syscall_readonly!(__NR_setsid))?;
         debug_assert!(pid > 0);
         Ok(Pid::from_raw_nonzero(RawNonZeroPid::new_unchecked(
             pid as u32,
         )))
     }
 }

 #[inline]
 pub(crate) fn kill_process(pid: Pid, sig: Signal) -> io::Result<()> {
     unsafe { ret(syscall_readonly!(__NR_kill, pid, sig)) }
 }

 #[inline]
 pub(crate) fn kill_process_group(pid: Pid, sig: Signal) -> io::Result<()> {
     unsafe { ret(syscall_readonly!(__NR_kill, negative_pid(pid), sig)) }
 }

 #[inline]
 pub(crate) fn kill_current_process_group(sig: Signal) -> io::Result<()> {
     unsafe { ret(syscall_readonly!(__NR_kill, pass_usize(0), sig)) }
 }

 #[inline]
 pub(crate) unsafe fn prctl(
     option: c::c_int,
     arg2: *mut c::c_void,
     arg3: *mut c::c_void,
     arg4: *mut c::c_void,
     arg5: *mut c::c_void,
 ) -> io::Result<c::c_int> {
     ret_c_int(syscall!(__NR_prctl, c_int(option), arg2, arg3, arg4, arg5))
 }

 #[inline]
 pub(crate) fn pidfd_open(pid: Pid, flags: PidfdFlags) -> io::Result<OwnedFd> {
     unsafe {
         ret_owned_fd(syscall_readonly!(
             __NR_pidfd_open,
             pid,
             c_int(flags.bits() as _)
         ))
     }
 }
	//! linux_raw syscalls supporting `rustix::process`.
	//!
	//! # Safety
	//!
	//! See the `rustix::backend` module documentation for details.
	#![allow(unsafe_code)]
	#![allow(clippy::undocumented_unsafe_blocks)]

	use super::super::c;
	use super::super::conv::{
	by_mut, by_ref, c_int, c_uint, negative_pid, pass_usize, ret, ret_c_int, ret_c_uint,
	ret_infallible, ret_usize, ret_usize_infallible, size_of, slice_just_addr, slice_mut, zero,
	};
	use super::types::{RawCpuSet, RawUname};
	use crate::backend::conv::ret_owned_fd;
	use crate::fd::{AsRawFd, BorrowedFd, OwnedFd};
	use crate::ffi::CStr;
	use crate::io;
	use crate::process::{
	Cpuid, Gid, MembarrierCommand, MembarrierQuery, Pid, PidfdFlags, RawNonZeroPid, RawPid,
	Resource, Rlimit, Signal, Uid, WaitId, WaitOptions, WaitStatus, WaitidOptions, WaitidStatus,
	};
	use core::convert::TryInto;
	use core::mem::MaybeUninit;
	use core::num::NonZeroU32;
	use core::ptr::{null, null_mut};
	use linux_raw_sys::general::{
	__kernel_gid_t, __kernel_pid_t, __kernel_uid_t, membarrier_cmd, membarrier_cmd_flag, rlimit,
	rlimit64, PRIO_PGRP, PRIO_PROCESS, PRIO_USER, RLIM64_INFINITY, RLIM_INFINITY,
	};
	#[cfg(not(target_os = "wasi"))]
	#[cfg(feature = "fs")]
	use {super::super::conv::ret_c_uint_infallible, crate::fs::Mode};

	#[inline]
	pub(crate) fn chdir(filename: &CStr) -> io::Result<()> {
	unsafe { ret(syscall_readonly!(__NR_chdir, filename)) }
	}

	#[inline]
	pub(crate) fn fchdir(fd: BorrowedFd<'_>) -> io::Result<()> {
	unsafe { ret(syscall_readonly!(__NR_fchdir, fd)) }
	}

	#[inline]
	pub(crate) fn getcwd(buf: &mut [u8]) -> io::Result<usize> {
	let (buf_addr_mut, buf_len) = slice_mut(buf);
	unsafe { ret_usize(syscall!(__NR_getcwd, buf_addr_mut, buf_len)) }
	}

	#[inline]
	pub(crate) fn membarrier_query() -> MembarrierQuery {
	unsafe {
	match ret_c_uint(syscall!(
	__NR_membarrier,
	c_int(membarrier_cmd::MEMBARRIER_CMD_QUERY as _),
	c_uint(0)
	)) {
	Ok(query) => {
	// SAFETY: The safety of `from_bits_unchecked` is discussed
	// [here]. Our "source of truth" is Linux, and here, the
	// `query` value is coming from Linux, so we know it only
	// contains "source of truth" valid bits.
	//
	// [here]: https://github.com/bitflags/bitflags/pull/207#issuecomment-671668662
	MembarrierQuery::from_bits_unchecked(query)
	}
	Err(_) => MembarrierQuery::empty(),
	}
	}
	}

	#[inline]
	pub(crate) fn membarrier(cmd: MembarrierCommand) -> io::Result<()> {
	unsafe { ret(syscall!(__NR_membarrier, cmd, c_uint(0))) }
	}

	#[inline]
	pub(crate) fn membarrier_cpu(cmd: MembarrierCommand, cpu: Cpuid) -> io::Result<()> {
	unsafe {
	ret(syscall!(
	__NR_membarrier,
	cmd,
	c_uint(membarrier_cmd_flag::MEMBARRIER_CMD_FLAG_CPU as _),
	cpu
	))
	}
	}

	#[inline]
	pub(crate) fn getpid() -> Pid {
	unsafe {
	let pid: i32 = ret_usize_infallible(syscall_readonly!(__NR_getpid)) as __kernel_pid_t;
	debug_assert!(pid > 0);
	Pid::from_raw_nonzero(RawNonZeroPid::new_unchecked(pid as u32))
	}
	}

	#[inline]
	pub(crate) fn getppid() -> Option<Pid> {
	unsafe {
	let ppid: i32 = ret_usize_infallible(syscall_readonly!(__NR_getppid)) as __kernel_pid_t;
	Pid::from_raw(ppid as u32)
	}
	}

	#[inline]
	pub(crate) fn getpgid(pid: Option<Pid>) -> io::Result<Pid> {
	unsafe {
	let pgid: i32 =
	ret_usize(syscall_readonly!(__NR_getpgid, c_uint(Pid::as_raw(pid))))? as __kernel_pid_t;
	Ok(Pid::from_raw_nonzero(NonZeroU32::new_unchecked(
	pgid as u32,
	)))
	}
	}

	#[inline]
	pub(crate) fn getpgrp() -> Pid {
	// Use the `getpgrp` syscall if available.
	#[cfg(not(any(target_arch = "aarch64", target_arch = "riscv64")))]
	unsafe {
	let pgid: i32 = ret_usize_infallible(syscall_readonly!(__NR_getpgrp)) as __kernel_pid_t;
	debug_assert!(pgid > 0);
	Pid::from_raw_nonzero(RawNonZeroPid::new_unchecked(pgid as u32))
	}

	// Otherwise use `getpgrp` and pass it zero.
	#[cfg(any(target_arch = "aarch64", target_arch = "riscv64"))]
	unsafe {
	let pgid: i32 =
	ret_usize_infallible(syscall_readonly!(__NR_getpgid, c_uint(0))) as __kernel_pid_t;
	debug_assert!(pgid > 0);
	Pid::from_raw_nonzero(RawNonZeroPid::new_unchecked(pgid as u32))
	}
	}

	#[inline]
	pub(crate) fn getgid() -> Gid {
	#[cfg(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm"))]
	unsafe {
	let gid: i32 =
	(ret_usize_infallible(syscall_readonly!(__NR_getgid32)) as __kernel_gid_t).into();
	Gid::from_raw(gid as u32)
	}
	#[cfg(not(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm")))]
	unsafe {
	let gid = ret_usize_infallible(syscall_readonly!(__NR_getgid)) as __kernel_gid_t;
	Gid::from_raw(gid as u32)
	}
	}

	#[inline]
	pub(crate) fn getegid() -> Gid {
	#[cfg(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm"))]
	unsafe {
	let gid: i32 =
	(ret_usize_infallible(syscall_readonly!(__NR_getegid32)) as __kernel_gid_t).into();
	Gid::from_raw(gid as u32)
	}
	#[cfg(not(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm")))]
	unsafe {
	let gid = ret_usize_infallible(syscall_readonly!(__NR_getegid)) as __kernel_gid_t;
	Gid::from_raw(gid as u32)
	}
	}

	#[inline]
	pub(crate) fn getuid() -> Uid {
	#[cfg(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm"))]
	unsafe {
	let uid = (ret_usize_infallible(syscall_readonly!(__NR_getuid32)) as __kernel_uid_t).into();
	Uid::from_raw(uid)
	}
	#[cfg(not(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm")))]
	unsafe {
	let uid = ret_usize_infallible(syscall_readonly!(__NR_getuid)) as __kernel_uid_t;
	Uid::from_raw(uid as u32)
	}
	}

	#[inline]
	pub(crate) fn geteuid() -> Uid {
	#[cfg(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm"))]
	unsafe {
	let uid: i32 =
	(ret_usize_infallible(syscall_readonly!(__NR_geteuid32)) as __kernel_uid_t).into();
	Uid::from_raw(uid as u32)
	}
	#[cfg(not(any(target_arch = "x86", target_arch = "sparc", target_arch = "arm")))]
	unsafe {
	let uid = ret_usize_infallible(syscall_readonly!(__NR_geteuid)) as __kernel_uid_t;
	Uid::from_raw(uid as u32)
	}
	}

	#[inline]
	pub(crate) fn sched_getaffinity(pid: Option<Pid>, cpuset: &mut RawCpuSet) -> io::Result<()> {
	unsafe {
	// The raw linux syscall returns the size (in bytes) of the `cpumask_t`
	// data type that is used internally by the kernel to represent the CPU
	// set bit mask.
	let size = ret_usize(syscall!(
	__NR_sched_getaffinity,
	c_uint(Pid::as_raw(pid)),
	size_of::<RawCpuSet, _>(),
	by_mut(&mut cpuset.bits)
	))?;
	let bytes = (cpuset as *mut RawCpuSet).cast::<u8>();
	let rest = bytes.wrapping_add(size);
	// Zero every byte in the cpuset not set by the kernel.
	rest.write_bytes(0, core::mem::size_of::<RawCpuSet>() - size);
	Ok(())
	}
	}

	#[inline]
	pub(crate) fn sched_setaffinity(pid: Option<Pid>, cpuset: &RawCpuSet) -> io::Result<()> {
	unsafe {
	ret(syscall_readonly!(
	__NR_sched_setaffinity,
	c_uint(Pid::as_raw(pid)),
	size_of::<RawCpuSet, _>(),
	slice_just_addr(&cpuset.bits)
	))
	}
	}

	#[inline]
	pub(crate) fn sched_yield() {
	unsafe {
	// See the documentation for [`crate::process::sched_yield`] for why
	// errors are ignored.
	syscall_readonly!(__NR_sched_yield).decode_void();
	}
	}

	#[inline]
	pub(crate) fn uname() -> RawUname {
	let mut uname = MaybeUninit::<RawUname>::uninit();
	unsafe {
	ret_infallible(syscall!(__NR_uname, &mut uname));
	uname.assume_init()
	}
	}

	#[cfg(feature = "fs")]
	#[inline]
	pub(crate) fn umask(mode: Mode) -> Mode {
	unsafe {
	// TODO: Use `from_bits_retain` when we switch to bitflags 2.0.
	Mode::from_bits_truncate(ret_c_uint_infallible(syscall_readonly!(__NR_umask, mode)))
	}
	}

	#[inline]
	pub(crate) fn nice(inc: i32) -> io::Result<i32> {
	let priority = if inc > -40 && inc < 40 {
	inc + getpriority_process(None)?
	} else {
	inc
	}
	// TODO: With Rust 1.50, use `.clamp` instead of `.min` and `.max`.
	//.clamp(-20, 19);
	.min(19)
	.max(-20);
	setpriority_process(None, priority)?;
	Ok(priority)
	}

	#[inline]
	pub(crate) fn getpriority_user(uid: Uid) -> io::Result<i32> {
	unsafe {
	Ok(20
	- ret_c_int(syscall_readonly!(
	__NR_getpriority,
	c_uint(PRIO_USER),
	c_uint(uid.as_raw())
	))?)
	}
	}

	#[inline]
	pub(crate) fn getpriority_pgrp(pgid: Option<Pid>) -> io::Result<i32> {
	unsafe {
	Ok(20
	- ret_c_int(syscall_readonly!(
	__NR_getpriority,
	c_uint(PRIO_PGRP),
	c_uint(Pid::as_raw(pgid))
	))?)
	}
	}

	#[inline]
	pub(crate) fn getpriority_process(pid: Option<Pid>) -> io::Result<i32> {
	unsafe {
	Ok(20
	- ret_c_int(syscall_readonly!(
	__NR_getpriority,
	c_uint(PRIO_PROCESS),
	c_uint(Pid::as_raw(pid))
	))?)
	}
	}

	#[inline]
	pub(crate) fn setpriority_user(uid: Uid, priority: i32) -> io::Result<()> {
	unsafe {
	ret(syscall_readonly!(
	__NR_setpriority,
	c_uint(PRIO_USER),
	c_uint(uid.as_raw()),
	c_int(priority)
	))
	}
	}

	#[inline]
	pub(crate) fn setpriority_pgrp(pgid: Option<Pid>, priority: i32) -> io::Result<()> {
	unsafe {
	ret(syscall_readonly!(
	__NR_setpriority,
	c_uint(PRIO_PGRP),
	c_uint(Pid::as_raw(pgid)),
	c_int(priority)
	))
	}
	}

	#[inline]
	pub(crate) fn setpriority_process(pid: Option<Pid>, priority: i32) -> io::Result<()> {
	unsafe {
	ret(syscall_readonly!(
	__NR_setpriority,
	c_uint(PRIO_PROCESS),
	c_uint(Pid::as_raw(pid)),
	c_int(priority)
	))
	}
	}

	#[inline]
	pub(crate) fn getrlimit(limit: Resource) -> Rlimit {
	let mut result = MaybeUninit::<rlimit64>::uninit();
	unsafe {
	match ret(syscall!(
	__NR_prlimit64,
	c_uint(0),
	limit,
	null::<c::c_void>(),
	&mut result
	)) {
	Ok(()) => rlimit_from_linux(result.assume_init()),
	Err(err) => {
	debug_assert_eq!(err, io::Errno::NOSYS);
	getrlimit_old(limit)
	}
	}
	}
	}

	/// The old 32-bit-only `getrlimit` syscall, for when we lack the new
	/// `prlimit64`.
	unsafe fn getrlimit_old(limit: Resource) -> Rlimit {
	let mut result = MaybeUninit::<rlimit>::uninit();

	// On these platforms, `__NR_getrlimit` is called `__NR_ugetrlimit`.
	#[cfg(any(
	target_arch = "arm",
	target_arch = "powerpc",
	target_arch = "powerpc64",
	target_arch = "x86",
	))]
	{
	ret_infallible(syscall!(__NR_ugetrlimit, limit, &mut result));
	}

	// On these platforms, it's just `__NR_getrlimit`.
	#[cfg(not(any(
	target_arch = "arm",
	target_arch = "powerpc",
	target_arch = "powerpc64",
	target_arch = "x86",
	)))]
	{
	ret_infallible(syscall!(__NR_getrlimit, limit, &mut result));
	}

	rlimit_from_linux_old(result.assume_init())
	}

	#[inline]
	pub(crate) fn setrlimit(limit: Resource, new: Rlimit) -> io::Result<()> {
	unsafe {
	let lim = rlimit_to_linux(new.clone());
	match ret(syscall_readonly!(
	__NR_prlimit64,
	c_uint(0),
	limit,
	by_ref(&lim),
	null_mut::<c::c_void>()
	)) {
	Ok(()) => Ok(()),
	Err(io::Errno::NOSYS) => setrlimit_old(limit, new),
	Err(err) => Err(err),
	}
	}
	}

	/// The old 32-bit-only `setrlimit` syscall, for when we lack the new
	/// `prlimit64`.
	unsafe fn setrlimit_old(limit: Resource, new: Rlimit) -> io::Result<()> {
	let lim = rlimit_to_linux_old(new)?;
	ret(syscall_readonly!(__NR_setrlimit, limit, by_ref(&lim)))
	}

	#[inline]
	pub(crate) fn prlimit(pid: Option<Pid>, limit: Resource, new: Rlimit) -> io::Result<Rlimit> {
	let lim = rlimit_to_linux(new);
	let mut result = MaybeUninit::<rlimit64>::uninit();
	unsafe {
	match ret(syscall!(
	__NR_prlimit64,
	c_uint(Pid::as_raw(pid)),
	limit,
	by_ref(&lim),
	&mut result
	)) {
	Ok(()) => Ok(rlimit_from_linux(result.assume_init())),
	Err(err) => Err(err),
	}
	}
	}

	/// Convert a Rust [`Rlimit`] to a C `rlimit64`.
	#[inline]
	fn rlimit_from_linux(lim: rlimit64) -> Rlimit {
	let current = if lim.rlim_cur == RLIM64_INFINITY as _ {
	None
	} else {
	Some(lim.rlim_cur)
	};
	let maximum = if lim.rlim_max == RLIM64_INFINITY as _ {
	None
	} else {
	Some(lim.rlim_max)
	};
	Rlimit { current, maximum }
	}

	/// Convert a C `rlimit64` to a Rust `Rlimit`.
	#[inline]
	fn rlimit_to_linux(lim: Rlimit) -> rlimit64 {
	let rlim_cur = match lim.current {
	Some(r) => r,
	None => RLIM64_INFINITY as _,
	};
	let rlim_max = match lim.maximum {
	Some(r) => r,
	None => RLIM64_INFINITY as _,
	};
	rlimit64 { rlim_cur, rlim_max }
	}

	/// Like `rlimit_from_linux` but uses Linux's old 32-bit `rlimit`.
	#[allow(clippy::useless_conversion)]
	fn rlimit_from_linux_old(lim: rlimit) -> Rlimit {
	let current = if lim.rlim_cur == RLIM_INFINITY as _ {
	None
	} else {
	Some(lim.rlim_cur.into())
	};
	let maximum = if lim.rlim_max == RLIM_INFINITY as _ {
	None
	} else {
	Some(lim.rlim_max.into())
	};
	Rlimit { current, maximum }
	}

	/// Like `rlimit_to_linux` but uses Linux's old 32-bit `rlimit`.
	#[allow(clippy::useless_conversion)]
	fn rlimit_to_linux_old(lim: Rlimit) -> io::Result<rlimit> {
	let rlim_cur = match lim.current {
	Some(r) => r.try_into().map_err(\|_e\| io::Errno::INVAL)?,
	None => RLIM_INFINITY as _,
	};
	let rlim_max = match lim.maximum {
	Some(r) => r.try_into().map_err(\|_e\| io::Errno::INVAL)?,
	None => RLIM_INFINITY as _,
	};
	Ok(rlimit { rlim_cur, rlim_max })
	}

	#[inline]
	pub(crate) fn wait(waitopts: WaitOptions) -> io::Result<Option<(Pid, WaitStatus)>> {
	_waitpid(!0, waitopts)
	}

	#[inline]
	pub(crate) fn waitpid(
	pid: Option<Pid>,
	waitopts: WaitOptions,
	) -> io::Result<Option<(Pid, WaitStatus)>> {
	_waitpid(Pid::as_raw(pid), waitopts)
	}

	#[inline]
	pub(crate) fn _waitpid(
	pid: RawPid,
	waitopts: WaitOptions,
	) -> io::Result<Option<(Pid, WaitStatus)>> {
	unsafe {
	let mut status = MaybeUninit::<u32>::uninit();
	let pid = ret_c_uint(syscall!(
	__NR_wait4,
	c_int(pid as _),
	&mut status,
	c_int(waitopts.bits() as _),
	zero()
	))?;
	Ok(RawNonZeroPid::new(pid).map(\|non_zero\| {
	(
	Pid::from_raw_nonzero(non_zero),
	WaitStatus::new(status.assume_init()),
	)
	}))
	}
	}

	#[inline]
	pub(crate) fn waitid(id: WaitId<'_>, options: WaitidOptions) -> io::Result<Option<WaitidStatus>> {
	// Get the id to wait on.
	match id {
	WaitId::All => _waitid_all(options),
	WaitId::Pid(pid) => _waitid_pid(pid, options),
	WaitId::PidFd(fd) => _waitid_pidfd(fd, options),
	}
	}

	#[inline]
	fn _waitid_all(options: WaitidOptions) -> io::Result<Option<WaitidStatus>> {
	let mut status = MaybeUninit::<c::siginfo_t>::uninit();
	unsafe {
	ret(syscall!(
	__NR_waitid,
	c_uint(c::P_ALL),
	c_uint(0),
	by_mut(&mut status),
	c_int(options.bits() as _),
	zero()
	))?
	};

	Ok(unsafe { cvt_waitid_status(status) })
	}

	#[inline]
	fn _waitid_pid(pid: Pid, options: WaitidOptions) -> io::Result<Option<WaitidStatus>> {
	let mut status = MaybeUninit::<c::siginfo_t>::uninit();
	unsafe {
	ret(syscall!(
	__NR_waitid,
	c_uint(c::P_PID),
	c_uint(Pid::as_raw(Some(pid))),
	by_mut(&mut status),
	c_int(options.bits() as _),
	zero()
	))?
	};

	Ok(unsafe { cvt_waitid_status(status) })
	}

	#[inline]
	fn _waitid_pidfd(fd: BorrowedFd<'_>, options: WaitidOptions) -> io::Result<Option<WaitidStatus>> {
	let mut status = MaybeUninit::<c::siginfo_t>::uninit();
	unsafe {
	ret(syscall!(
	__NR_waitid,
	c_uint(c::P_PIDFD),
	c_uint(fd.as_raw_fd() as _),
	by_mut(&mut status),
	c_int(options.bits() as _),
	zero()
	))?
	};

	Ok(unsafe { cvt_waitid_status(status) })
	}

	/// Convert a `siginfo_t` to a `WaitidStatus`.
	///
	/// # Safety
	///
	/// The caller must ensure that `status` is initialized and that `waitid`
	/// returned successfully.
	#[inline]
	unsafe fn cvt_waitid_status(status: MaybeUninit<c::siginfo_t>) -> Option<WaitidStatus> {
	let status = status.assume_init();
	if status.__bindgen_anon_1.__bindgen_anon_1.si_signo == 0 {
	None
	} else {
	Some(WaitidStatus(status))
	}
	}

	#[cfg(feature = "runtime")]
	#[inline]
	pub(crate) fn exit_group(code: c::c_int) -> ! {
	unsafe { syscall_noreturn!(__NR_exit_group, c_int(code)) }
	}

	#[inline]
	pub(crate) fn setsid() -> io::Result<Pid> {
	unsafe {
	let pid = ret_usize(syscall_readonly!(__NR_setsid))?;
	debug_assert!(pid > 0);
	Ok(Pid::from_raw_nonzero(RawNonZeroPid::new_unchecked(
	pid as u32,
	)))
	}
	}

	#[inline]
	pub(crate) fn kill_process(pid: Pid, sig: Signal) -> io::Result<()> {
	unsafe { ret(syscall_readonly!(__NR_kill, pid, sig)) }
	}

	#[inline]
	pub(crate) fn kill_process_group(pid: Pid, sig: Signal) -> io::Result<()> {
	unsafe { ret(syscall_readonly!(__NR_kill, negative_pid(pid), sig)) }
	}

	#[inline]
	pub(crate) fn kill_current_process_group(sig: Signal) -> io::Result<()> {
	unsafe { ret(syscall_readonly!(__NR_kill, pass_usize(0), sig)) }
	}

	#[inline]
	pub(crate) unsafe fn prctl(
	option: c::c_int,
	arg2: *mut c::c_void,
	arg3: *mut c::c_void,
	arg4: *mut c::c_void,
	arg5: *mut c::c_void,
	) -> io::Result<c::c_int> {
	ret_c_int(syscall!(__NR_prctl, c_int(option), arg2, arg3, arg4, arg5))
	}

	#[inline]
	pub(crate) fn pidfd_open(pid: Pid, flags: PidfdFlags) -> io::Result<OwnedFd> {
	unsafe {
	ret_owned_fd(syscall_readonly!(
	__NR_pidfd_open,
	pid,
	c_int(flags.bits() as _)
	))
	}
	}