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//! libc syscalls supporting `rustix::io`.
use crate::backend::c;
#[cfg(not(target_os = "wasi"))]
use crate::backend::conv::ret_discarded_fd;
use crate::backend::conv::{borrowed_fd, ret, ret_c_int, ret_owned_fd, ret_usize};
use crate::fd::{AsFd, BorrowedFd, OwnedFd, RawFd};
#[cfg(not(any(
target_os = "aix",
target_os = "espidf",
target_os = "nto",
target_os = "vita",
target_os = "wasi"
)))]
use crate::io::DupFlags;
#[cfg(linux_kernel)]
use crate::io::ReadWriteFlags;
use crate::io::{self, FdFlags};
use crate::ioctl::{IoctlOutput, RawOpcode};
use core::cmp::min;
#[cfg(all(feature = "fs", feature = "net"))]
use libc_errno::errno;
#[cfg(not(any(target_os = "espidf", target_os = "horizon")))]
use {
crate::backend::MAX_IOV,
crate::io::{IoSlice, IoSliceMut},
};
pub(crate) unsafe fn read(fd: BorrowedFd<'_>, buf: *mut u8, len: usize) -> io::Result<usize> {
ret_usize(c::read(borrowed_fd(fd), buf.cast(), min(len, READ_LIMIT)))
}
pub(crate) fn write(fd: BorrowedFd<'_>, buf: &[u8]) -> io::Result<usize> {
unsafe {
ret_usize(c::write(
borrowed_fd(fd),
buf.as_ptr().cast(),
min(buf.len(), READ_LIMIT),
))
}
}
pub(crate) unsafe fn pread(
fd: BorrowedFd<'_>,
buf: *mut u8,
len: usize,
offset: u64,
) -> io::Result<usize> {
let len = min(len, READ_LIMIT);
// Silently cast; we'll get `EINVAL` if the value is negative.
let offset = offset as i64;
// ESP-IDF and Vita don't support 64-bit offsets.
#[cfg(any(target_os = "espidf", target_os = "vita"))]
let offset: i32 = offset.try_into().map_err(|_| io::Errno::OVERFLOW)?;
ret_usize(c::pread(borrowed_fd(fd), buf.cast(), len, offset))
}
pub(crate) fn pwrite(fd: BorrowedFd<'_>, buf: &[u8], offset: u64) -> io::Result<usize> {
let len = min(buf.len(), READ_LIMIT);
// Silently cast; we'll get `EINVAL` if the value is negative.
let offset = offset as i64;
// ESP-IDF and Vita don't support 64-bit offsets.
#[cfg(any(target_os = "espidf", target_os = "vita"))]
let offset: i32 = offset.try_into().map_err(|_| io::Errno::OVERFLOW)?;
unsafe { ret_usize(c::pwrite(borrowed_fd(fd), buf.as_ptr().cast(), len, offset)) }
}
#[cfg(not(any(target_os = "espidf", target_os = "horizon")))]
pub(crate) fn readv(fd: BorrowedFd<'_>, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
unsafe {
ret_usize(c::readv(
borrowed_fd(fd),
bufs.as_ptr().cast::<c::iovec>(),
min(bufs.len(), MAX_IOV) as c::c_int,
))
}
}
#[cfg(not(any(target_os = "espidf", target_os = "horizon")))]
pub(crate) fn writev(fd: BorrowedFd<'_>, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
unsafe {
ret_usize(c::writev(
borrowed_fd(fd),
bufs.as_ptr().cast::<c::iovec>(),
min(bufs.len(), MAX_IOV) as c::c_int,
))
}
}
#[cfg(not(any(
target_os = "espidf",
target_os = "haiku",
target_os = "horizon",
target_os = "nto",
target_os = "redox",
target_os = "solaris",
target_os = "vita"
)))]
pub(crate) fn preadv(
fd: BorrowedFd<'_>,
bufs: &mut [IoSliceMut<'_>],
offset: u64,
) -> io::Result<usize> {
// Silently cast; we'll get `EINVAL` if the value is negative.
let offset = offset as i64;
unsafe {
ret_usize(c::preadv(
borrowed_fd(fd),
bufs.as_ptr().cast::<c::iovec>(),
min(bufs.len(), MAX_IOV) as c::c_int,
offset,
))
}
}
#[cfg(not(any(
target_os = "espidf",
target_os = "haiku",
target_os = "nto",
target_os = "horizon",
target_os = "redox",
target_os = "solaris",
target_os = "vita"
)))]
pub(crate) fn pwritev(fd: BorrowedFd<'_>, bufs: &[IoSlice<'_>], offset: u64) -> io::Result<usize> {
// Silently cast; we'll get `EINVAL` if the value is negative.
let offset = offset as i64;
unsafe {
ret_usize(c::pwritev(
borrowed_fd(fd),
bufs.as_ptr().cast::<c::iovec>(),
min(bufs.len(), MAX_IOV) as c::c_int,
offset,
))
}
}
#[cfg(linux_kernel)]
pub(crate) fn preadv2(
fd: BorrowedFd<'_>,
bufs: &mut [IoSliceMut<'_>],
offset: u64,
flags: ReadWriteFlags,
) -> io::Result<usize> {
// Silently cast; we'll get `EINVAL` if the value is negative.
let offset = offset as i64;
unsafe {
ret_usize(c::preadv2(
borrowed_fd(fd),
bufs.as_ptr().cast::<c::iovec>(),
min(bufs.len(), MAX_IOV) as c::c_int,
offset,
bitflags_bits!(flags),
))
}
}
#[cfg(linux_kernel)]
pub(crate) fn pwritev2(
fd: BorrowedFd<'_>,
bufs: &[IoSlice<'_>],
offset: u64,
flags: ReadWriteFlags,
) -> io::Result<usize> {
// Silently cast; we'll get `EINVAL` if the value is negative.
let offset = offset as i64;
unsafe {
ret_usize(c::pwritev2(
borrowed_fd(fd),
bufs.as_ptr().cast::<c::iovec>(),
min(bufs.len(), MAX_IOV) as c::c_int,
offset,
bitflags_bits!(flags),
))
}
}
// These functions are derived from Rust's library/std/src/sys/unix/fd.rs at
// revision 326ef470a8b379a180d6dc4bbef08990698a737a.
// The maximum read limit on most POSIX-like systems is `SSIZE_MAX`, with the
// manual page quoting that if the count of bytes to read is greater than
// `SSIZE_MAX` the result is “unspecified”.
//
// On macOS, however, apparently the 64-bit libc is either buggy or
// intentionally showing odd behavior by rejecting any read with a size larger
// than or equal to `INT_MAX`. To handle both of these the read size is capped
// on both platforms.
#[cfg(target_os = "macos")]
const READ_LIMIT: usize = c::c_int::MAX as usize - 1;
#[cfg(not(target_os = "macos"))]
const READ_LIMIT: usize = c::ssize_t::MAX as usize;
pub(crate) unsafe fn close(raw_fd: RawFd) {
let _ = c::close(raw_fd as c::c_int);
}
#[inline]
pub(crate) unsafe fn ioctl(
fd: BorrowedFd<'_>,
request: RawOpcode,
arg: *mut c::c_void,
) -> io::Result<IoctlOutput> {
ret_c_int(c::ioctl(borrowed_fd(fd), request, arg))
}
#[inline]
pub(crate) unsafe fn ioctl_readonly(
fd: BorrowedFd<'_>,
request: RawOpcode,
arg: *mut c::c_void,
) -> io::Result<IoctlOutput> {
ioctl(fd, request, arg)
}
#[cfg(not(any(target_os = "redox", target_os = "wasi")))]
#[cfg(all(feature = "fs", feature = "net"))]
pub(crate) fn is_read_write(fd: BorrowedFd<'_>) -> io::Result<(bool, bool)> {
use core::mem::MaybeUninit;
let (mut read, mut write) = crate::fs::fd::_is_file_read_write(fd)?;
let mut not_socket = false;
if read {
// Do a `recv` with `PEEK` and `DONTWAIT` for 1 byte. A 0 indicates
// the read side is shut down; an `EWOULDBLOCK` indicates the read
// side is still open.
match unsafe {
c::recv(
borrowed_fd(fd),
MaybeUninit::<[u8; 1]>::uninit()
.as_mut_ptr()
.cast::<c::c_void>(),
1,
c::MSG_PEEK | c::MSG_DONTWAIT,
)
} {
0 => read = false,
-1 => {
#[allow(unreachable_patterns)] // `EAGAIN` may equal `EWOULDBLOCK`
match errno().0 {
c::EAGAIN | c::EWOULDBLOCK => (),
c::ENOTSOCK => not_socket = true,
err => return Err(io::Errno(err)),
}
}
_ => (),
}
}
if write && !not_socket {
// Do a `send` with `DONTWAIT` for 0 bytes. An `EPIPE` indicates
// the write side is shut down.
if unsafe { c::send(borrowed_fd(fd), [].as_ptr(), 0, c::MSG_DONTWAIT) } == -1 {
#[allow(unreachable_patterns)] // `EAGAIN` may equal `EWOULDBLOCK`
match errno().0 {
c::EAGAIN | c::EWOULDBLOCK | c::ENOTSOCK => (),
c::EPIPE => write = false,
err => return Err(io::Errno(err)),
}
}
}
Ok((read, write))
}
#[cfg(target_os = "wasi")]
#[cfg(all(feature = "fs", feature = "net"))]
pub(crate) fn is_read_write(_fd: BorrowedFd<'_>) -> io::Result<(bool, bool)> {
todo!("Implement is_read_write for WASI in terms of fd_fdstat_get");
}
pub(crate) fn fcntl_getfd(fd: BorrowedFd<'_>) -> io::Result<FdFlags> {
let flags = unsafe { ret_c_int(c::fcntl(borrowed_fd(fd), c::F_GETFD))? };
Ok(FdFlags::from_bits_retain(bitcast!(flags)))
}
pub(crate) fn fcntl_setfd(fd: BorrowedFd<'_>, flags: FdFlags) -> io::Result<()> {
unsafe { ret(c::fcntl(borrowed_fd(fd), c::F_SETFD, flags.bits())) }
}
#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
pub(crate) fn fcntl_dupfd_cloexec(fd: BorrowedFd<'_>, min: RawFd) -> io::Result<OwnedFd> {
unsafe { ret_owned_fd(c::fcntl(borrowed_fd(fd), c::F_DUPFD_CLOEXEC, min)) }
}
#[cfg(target_os = "espidf")]
pub(crate) fn fcntl_dupfd(fd: BorrowedFd<'_>, min: RawFd) -> io::Result<OwnedFd> {
unsafe { ret_owned_fd(c::fcntl(borrowed_fd(fd), c::F_DUPFD, min)) }
}
#[cfg(not(target_os = "wasi"))]
pub(crate) fn dup(fd: BorrowedFd<'_>) -> io::Result<OwnedFd> {
unsafe { ret_owned_fd(c::dup(borrowed_fd(fd))) }
}
#[allow(clippy::needless_pass_by_ref_mut)]
#[cfg(not(target_os = "wasi"))]
pub(crate) fn dup2(fd: BorrowedFd<'_>, new: &mut OwnedFd) -> io::Result<()> {
unsafe { ret_discarded_fd(c::dup2(borrowed_fd(fd), borrowed_fd(new.as_fd()))) }
}
#[allow(clippy::needless_pass_by_ref_mut)]
#[cfg(not(any(
apple,
target_os = "aix",
target_os = "android",
target_os = "dragonfly",
target_os = "espidf",
target_os = "haiku",
target_os = "horizon",
target_os = "nto",
target_os = "redox",
target_os = "vita",
target_os = "wasi",
)))]
pub(crate) fn dup3(fd: BorrowedFd<'_>, new: &mut OwnedFd, flags: DupFlags) -> io::Result<()> {
unsafe {
ret_discarded_fd(c::dup3(
borrowed_fd(fd),
borrowed_fd(new.as_fd()),
bitflags_bits!(flags),
))
}
}
#[cfg(any(
apple,
target_os = "android",
target_os = "dragonfly",
target_os = "haiku",
target_os = "redox",
))]
pub(crate) fn dup3(fd: BorrowedFd<'_>, new: &mut OwnedFd, _flags: DupFlags) -> io::Result<()> {
// Android 5.0 has `dup3`, but libc doesn't have bindings. Emulate it
// using `dup2`. We don't need to worry about the difference between
// `dup2` and `dup3` when the file descriptors are equal because we
// have an `&mut OwnedFd` which means `fd` doesn't alias it.
dup2(fd, new)
}