| //! 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 = "wasi" |
| )))] |
| use crate::io::DupFlags; |
| #[cfg(linux_kernel)] |
| use crate::io::ReadWriteFlags; |
| use crate::io::{self, FdFlags}; |
| use core::cmp::min; |
| #[cfg(all(feature = "fs", feature = "net"))] |
| use libc_errno::errno; |
| #[cfg(not(target_os = "espidf"))] |
| use { |
| crate::backend::MAX_IOV, |
| crate::io::{IoSlice, IoSliceMut}, |
| }; |
| |
| pub(crate) fn read(fd: BorrowedFd<'_>, buf: &mut [u8]) -> io::Result<usize> { |
| unsafe { |
| ret_usize(c::read( |
| borrowed_fd(fd), |
| buf.as_mut_ptr().cast(), |
| min(buf.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) fn pread(fd: BorrowedFd<'_>, buf: &mut [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 doesn't support 64-bit offsets. |
| #[cfg(target_os = "espidf")] |
| let offset: i32 = offset.try_into().map_err(|_| io::Errno::OVERFLOW)?; |
| |
| unsafe { |
| ret_usize(c::pread( |
| borrowed_fd(fd), |
| buf.as_mut_ptr().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 doesn't support 64-bit offsets. |
| #[cfg(target_os = "espidf")] |
| 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(target_os = "espidf"))] |
| 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(target_os = "espidf"))] |
| 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 = "nto", |
| target_os = "redox", |
| target_os = "solaris" |
| )))] |
| 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 = "redox", |
| target_os = "solaris" |
| )))] |
| 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); |
| } |
| |
| #[cfg(not(target_os = "espidf"))] |
| pub(crate) fn ioctl_fionread(fd: BorrowedFd<'_>) -> io::Result<u64> { |
| use core::mem::MaybeUninit; |
| |
| let mut nread = MaybeUninit::<c::c_int>::uninit(); |
| unsafe { |
| ret(c::ioctl(borrowed_fd(fd), c::FIONREAD, nread.as_mut_ptr()))?; |
| // `FIONREAD` returns the number of bytes silently casted to a `c_int`, |
| // even when this is lossy. The best we can do is convert it back to a |
| // `u64` without sign-extending it back first. |
| Ok(u64::from(nread.assume_init() as c::c_uint)) |
| } |
| } |
| |
| pub(crate) fn ioctl_fionbio(fd: BorrowedFd<'_>, value: bool) -> io::Result<()> { |
| unsafe { |
| let data = value as c::c_int; |
| ret(c::ioctl(borrowed_fd(fd), c::FIONBIO, &data)) |
| } |
| } |
| |
| #[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))) } |
| } |
| |
| #[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()))) } |
| } |
| |
| #[cfg(not(any( |
| apple, |
| target_os = "aix", |
| target_os = "android", |
| target_os = "dragonfly", |
| target_os = "espidf", |
| target_os = "haiku", |
| target_os = "nto", |
| target_os = "redox", |
| 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) |
| } |
| |
| #[cfg(apple)] |
| pub(crate) fn ioctl_fioclex(fd: BorrowedFd<'_>) -> io::Result<()> { |
| unsafe { |
| ret(c::ioctl( |
| borrowed_fd(fd), |
| c::FIOCLEX, |
| core::ptr::null_mut::<u8>(), |
| )) |
| } |
| } |
