1 files changed, 330 insertions, 0 deletions
diff --git a/library/std/src/sys/unix/fd.rs b/library/std/src/sys/unix/fd.rs
new file mode 100644
index 000000000..30812dabb
--- /dev/null
+++ b/library/std/src/sys/unix/fd.rs
@@ -0,0 +1,330 @@
+#![unstable(reason = "not public", issue = "none", feature = "fd")]
+
+#[cfg(test)]
+mod tests;
+
+use crate::cmp;
+use crate::io::{self, IoSlice, IoSliceMut, Read, ReadBuf};
+use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
+use crate::sys::cvt;
+use crate::sys_common::{AsInner, FromInner, IntoInner};
+
+#[cfg(any(
+    target_os = "android",
+    target_os = "linux",
+    target_os = "emscripten",
+    target_os = "l4re"
+))]
+use libc::off64_t;
+#[cfg(not(any(
+    target_os = "linux",
+    target_os = "emscripten",
+    target_os = "l4re",
+    target_os = "android"
+)))]
+use libc::off_t as off64_t;
+
+#[derive(Debug)]
+pub struct FileDesc(OwnedFd);
+
+// The maximum read limit on most POSIX-like systems is `SSIZE_MAX`,
+// with the man 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 = libc::c_int::MAX as usize - 1;
+#[cfg(not(target_os = "macos"))]
+const READ_LIMIT: usize = libc::ssize_t::MAX as usize;
+
+#[cfg(any(
+    target_os = "dragonfly",
+    target_os = "freebsd",
+    target_os = "ios",
+    target_os = "macos",
+    target_os = "netbsd",
+    target_os = "openbsd",
+    target_os = "watchos",
+))]
+const fn max_iov() -> usize {
+    libc::IOV_MAX as usize
+}
+
+#[cfg(any(target_os = "android", target_os = "emscripten", target_os = "linux"))]
+const fn max_iov() -> usize {
+    libc::UIO_MAXIOV as usize
+}
+
+#[cfg(not(any(
+    target_os = "android",
+    target_os = "dragonfly",
+    target_os = "emscripten",
+    target_os = "freebsd",
+    target_os = "ios",
+    target_os = "linux",
+    target_os = "macos",
+    target_os = "netbsd",
+    target_os = "openbsd",
+    target_os = "horizon",
+    target_os = "watchos",
+)))]
+const fn max_iov() -> usize {
+    16 // The minimum value required by POSIX.
+}
+
+impl FileDesc {
+    pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
+        let ret = cvt(unsafe {
+            libc::read(
+                self.as_raw_fd(),
+                buf.as_mut_ptr() as *mut libc::c_void,
+                cmp::min(buf.len(), READ_LIMIT),
+            )
+        })?;
+        Ok(ret as usize)
+    }
+
+    #[cfg(not(any(target_os = "espidf", target_os = "horizon")))]
+    pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        let ret = cvt(unsafe {
+            libc::readv(
+                self.as_raw_fd(),
+                bufs.as_ptr() as *const libc::iovec,
+                cmp::min(bufs.len(), max_iov()) as libc::c_int,
+            )
+        })?;
+        Ok(ret as usize)
+    }
+
+    #[cfg(any(target_os = "espidf", target_os = "horizon"))]
+    pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        return crate::io::default_read_vectored(|b| self.read(b), bufs);
+    }
+
+    #[inline]
+    pub fn is_read_vectored(&self) -> bool {
+        cfg!(not(any(target_os = "espidf", target_os = "horizon")))
+    }
+
+    pub fn read_to_end(&self, buf: &mut Vec<u8>) -> io::Result<usize> {
+        let mut me = self;
+        (&mut me).read_to_end(buf)
+    }
+
+    pub fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
+        #[cfg(not(any(target_os = "linux", target_os = "android")))]
+        use libc::pread as pread64;
+        #[cfg(any(target_os = "linux", target_os = "android"))]
+        use libc::pread64;
+
+        unsafe {
+            cvt(pread64(
+                self.as_raw_fd(),
+                buf.as_mut_ptr() as *mut libc::c_void,
+                cmp::min(buf.len(), READ_LIMIT),
+                offset as off64_t,
+            ))
+            .map(|n| n as usize)
+        }
+    }
+
+    pub fn read_buf(&self, buf: &mut ReadBuf<'_>) -> io::Result<()> {
+        let ret = cvt(unsafe {
+            libc::read(
+                self.as_raw_fd(),
+                buf.unfilled_mut().as_mut_ptr() as *mut libc::c_void,
+                cmp::min(buf.remaining(), READ_LIMIT),
+            )
+        })?;
+
+        // Safety: `ret` bytes were written to the initialized portion of the buffer
+        unsafe {
+            buf.assume_init(ret as usize);
+        }
+        buf.add_filled(ret as usize);
+        Ok(())
+    }
+
+    pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
+        let ret = cvt(unsafe {
+            libc::write(
+                self.as_raw_fd(),
+                buf.as_ptr() as *const libc::c_void,
+                cmp::min(buf.len(), READ_LIMIT),
+            )
+        })?;
+        Ok(ret as usize)
+    }
+
+    #[cfg(not(any(target_os = "espidf", target_os = "horizon")))]
+    pub fn write_vectored(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        let ret = cvt(unsafe {
+            libc::writev(
+                self.as_raw_fd(),
+                bufs.as_ptr() as *const libc::iovec,
+                cmp::min(bufs.len(), max_iov()) as libc::c_int,
+            )
+        })?;
+        Ok(ret as usize)
+    }
+
+    #[cfg(any(target_os = "espidf", target_os = "horizon"))]
+    pub fn write_vectored(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        return crate::io::default_write_vectored(|b| self.write(b), bufs);
+    }
+
+    #[inline]
+    pub fn is_write_vectored(&self) -> bool {
+        cfg!(not(any(target_os = "espidf", target_os = "horizon")))
+    }
+
+    pub fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
+        #[cfg(not(any(target_os = "linux", target_os = "android")))]
+        use libc::pwrite as pwrite64;
+        #[cfg(any(target_os = "linux", target_os = "android"))]
+        use libc::pwrite64;
+
+        unsafe {
+            cvt(pwrite64(
+                self.as_raw_fd(),
+                buf.as_ptr() as *const libc::c_void,
+                cmp::min(buf.len(), READ_LIMIT),
+                offset as off64_t,
+            ))
+            .map(|n| n as usize)
+        }
+    }
+
+    #[cfg(target_os = "linux")]
+    pub fn get_cloexec(&self) -> io::Result<bool> {
+        unsafe { Ok((cvt(libc::fcntl(self.as_raw_fd(), libc::F_GETFD))? & libc::FD_CLOEXEC) != 0) }
+    }
+
+    #[cfg(not(any(
+        target_env = "newlib",
+        target_os = "solaris",
+        target_os = "illumos",
+        target_os = "emscripten",
+        target_os = "fuchsia",
+        target_os = "l4re",
+        target_os = "linux",
+        target_os = "haiku",
+        target_os = "redox",
+        target_os = "vxworks"
+    )))]
+    pub fn set_cloexec(&self) -> io::Result<()> {
+        unsafe {
+            cvt(libc::ioctl(self.as_raw_fd(), libc::FIOCLEX))?;
+            Ok(())
+        }
+    }
+    #[cfg(any(
+        all(target_env = "newlib", not(any(target_os = "espidf", target_os = "horizon"))),
+        target_os = "solaris",
+        target_os = "illumos",
+        target_os = "emscripten",
+        target_os = "fuchsia",
+        target_os = "l4re",
+        target_os = "linux",
+        target_os = "haiku",
+        target_os = "redox",
+        target_os = "vxworks"
+    ))]
+    pub fn set_cloexec(&self) -> io::Result<()> {
+        unsafe {
+            let previous = cvt(libc::fcntl(self.as_raw_fd(), libc::F_GETFD))?;
+            let new = previous | libc::FD_CLOEXEC;
+            if new != previous {
+                cvt(libc::fcntl(self.as_raw_fd(), libc::F_SETFD, new))?;
+            }
+            Ok(())
+        }
+    }
+    #[cfg(any(target_os = "espidf", target_os = "horizon"))]
+    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.
+        Ok(())
+    }
+
+    #[cfg(target_os = "linux")]
+    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
+        unsafe {
+            let v = nonblocking as libc::c_int;
+            cvt(libc::ioctl(self.as_raw_fd(), libc::FIONBIO, &v))?;
+            Ok(())
+        }
+    }
+
+    #[cfg(not(target_os = "linux"))]
+    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
+        unsafe {
+            let previous = cvt(libc::fcntl(self.as_raw_fd(), libc::F_GETFL))?;
+            let new = if nonblocking {
+                previous | libc::O_NONBLOCK
+            } else {
+                previous & !libc::O_NONBLOCK
+            };
+            if new != previous {
+                cvt(libc::fcntl(self.as_raw_fd(), libc::F_SETFL, new))?;
+            }
+            Ok(())
+        }
+    }
+
+    #[inline]
+    pub fn duplicate(&self) -> io::Result<FileDesc> {
+        Ok(Self(self.0.try_clone()?))
+    }
+}
+
+impl<'a> Read for &'a FileDesc {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        (**self).read(buf)
+    }
+}
+
+impl AsInner<OwnedFd> for FileDesc {
+    fn as_inner(&self) -> &OwnedFd {
+        &self.0
+    }
+}
+
+impl IntoInner<OwnedFd> for FileDesc {
+    fn into_inner(self) -> OwnedFd {
+        self.0
+    }
+}
+
+impl FromInner<OwnedFd> for FileDesc {
+    fn from_inner(owned_fd: OwnedFd) -> Self {
+        Self(owned_fd)
+    }
+}
+
+impl AsFd for FileDesc {
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        self.0.as_fd()
+    }
+}
+
+impl AsRawFd for FileDesc {
+    fn as_raw_fd(&self) -> RawFd {
+        self.0.as_raw_fd()
+    }
+}
+
+impl IntoRawFd for FileDesc {
+    fn into_raw_fd(self) -> RawFd {
+        self.0.into_raw_fd()
+    }
+}
+
+impl FromRawFd for FileDesc {
+    unsafe fn from_raw_fd(raw_fd: RawFd) -> Self {
+        Self(FromRawFd::from_raw_fd(raw_fd))
+    }
+}