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// Forked from https://github.com/Thomasdezeeuw/sendfile/blob/024f82cd4dede9048392a5bd6d8afcd4d5aa83d5/src/lib.rs// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
use std::future::Future;use std::io;use std::os::unix::io::RawFd;use std::pin::Pin;use std::task::{self, Poll};
pub struct SendFile {  pub io: (RawFd, RawFd),  pub written: usize,}
impl SendFile {  #[inline]  pub fn try_send(&mut self) -> Result<usize, std::io::Error> {    #[cfg(target_os = "linux")]    {      // This is the maximum the Linux kernel will write in a single call.      let count = 0x7ffff000;      let mut offset = self.written as libc::off_t;
      let res =        // SAFETY: call to libc::sendfile()        unsafe { libc::sendfile(self.io.1, self.io.0, &mut offset, count) };      if res == -1 {        Err(io::Error::last_os_error())      } else {        self.written = offset as usize;        Ok(res as usize)      }    }    #[cfg(target_os = "macos")]    {      // Send all bytes.      let mut length = 0;      // On macOS `length` is value-result parameter. It determines the number      // of bytes to write and returns the number of bytes written also in      // case of `EAGAIN` errors.      // SAFETY: call to libc::sendfile()      let res = unsafe {        libc::sendfile(          self.io.0,          self.io.1,          self.written as libc::off_t,          &mut length,          std::ptr::null_mut(),          0,        )      };      self.written += length as usize;      if res == -1 {        Err(io::Error::last_os_error())      } else {        Ok(length as usize)      }    }  }}
impl Future for SendFile {  type Output = Result<(), std::io::Error>;
  fn poll(    mut self: Pin<&mut Self>,    _: &mut task::Context<'_>,  ) -> Poll<Self::Output> {    loop {      match self.try_send() {        Ok(0) => break Poll::Ready(Ok(())),        Ok(_) => continue,        Err(ref err) if err.kind() == io::ErrorKind::WouldBlock => {          break Poll::Pending        }        Err(ref err) if err.kind() == io::ErrorKind::Interrupted => continue, // Try again.        Err(err) => break Poll::Ready(Err(err)),      }    }  }}