bjorn3
80 lines
2.1 KiB
Rust
80 lines
2.1 KiB
Rust
#![feature(never_type)]
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use std::io;
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#[must_use = "Daemon::ready must be called"]
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pub struct Daemon {
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write_pipe: libc::c_int,
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}
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fn errno() -> io::Error {
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io::Error::last_os_error()
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}
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impl Daemon {
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pub fn new<F: FnOnce(Daemon) -> !>(f: F) -> io::Result<!> {
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let mut pipes = [0; 2];
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match unsafe { libc::pipe(pipes.as_mut_ptr()) } {
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0 => (),
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-1 => return Err(errno()),
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_ => unreachable!(),
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}
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let [read_pipe, write_pipe] = pipes;
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match unsafe { libc::fork() } {
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0 => {
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let _ = unsafe { libc::close(read_pipe) };
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f(Daemon { write_pipe })
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}
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-1 => return Err(errno()),
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_pid => {
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let _ = unsafe { libc::close(write_pipe) };
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let mut data = [0];
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let res = loop {
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match unsafe { libc::read(read_pipe, data.as_mut_ptr().cast(), data.len()) } {
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-1 if errno().kind() == io::ErrorKind::Interrupted => continue,
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-1 => break Err(errno()),
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count => break Ok(count as usize),
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}
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};
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let _ = unsafe { libc::close(read_pipe) };
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if res? == 1 {
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unsafe { libc::_exit(data[0].into()) };
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} else {
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Err(io::Error::from_raw_os_error(libc::EIO))
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}
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}
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}
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}
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pub fn ready(self) -> io::Result<()> {
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let res;
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unsafe {
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let src = [0_u8];
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res = loop {
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match libc::write(self.write_pipe, src.as_ptr().cast(), src.len()) {
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-1 if errno().kind() == io::ErrorKind::Interrupted => continue,
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-1 => break Err(errno()),
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count => break Ok(count),
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}
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};
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let _ = libc::close(self.write_pipe);
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}
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if res? == 1 {
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Ok(())
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} else {
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Err(io::Error::from_raw_os_error(libc::EIO))
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}
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}
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}
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