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use crate::{
BufResult, api::resource::Resource, buf::BufLike, typed_op::TypedOp,
};
pub struct ReadAt<T>
where
T: Send + Sync,
{
res: Resource,
buf: Option<T>,
offset: i64,
}
impl<T> ReadAt<T>
where
T: Send + Sync,
{
/// Will return errn 22 "EINVAL" if offset < 0
pub(crate) fn new(res: Resource, mem: T, offset: i64) -> Self
where
T: BufLike,
{
Self { res, buf: Some(mem), offset }
}
pub fn to_op(mut self) -> crate::op::Op
where
T: BufLike + 'static,
{
let buffer = self.buf.take().expect("buffer already taken");
crate::op::Op::ReadAt {
fd: self.res,
offset: self.offset,
buffer: crate::op::OpBuf::new(buffer),
}
}
}
impl<T> TypedOp for ReadAt<T>
where
T: BufLike + Send + Sync + 'static,
{
type Result = BufResult<i32, T>;
fn into_op(&mut self) -> crate::op::Op {
let slice = self.buf.as_mut().expect("buffer not available").buf();
let ptr = slice.as_ptr() as *mut u8;
let len = slice.len();
crate::op::Op::ReadAt {
fd: self.res.clone(),
offset: self.offset,
buffer: crate::op::OpBuf::new(crate::op::RawBuf { ptr, len }),
}
}
fn extract_result(self, res: isize) -> Self::Result {
let buf = self.buf.expect("buffer not available");
if res < 0 {
// On error, return buffer unchanged
(Err(std::io::Error::from_raw_os_error((-res) as i32)), buf)
} else {
// On success, truncate buffer to read bytes
(Ok(res as i32), buf.after(res as usize))
}
}
// #[cfg(unix)]
// fn meta(&self) -> crate::operation::OpMeta {
// crate::operation::OpMeta::CAP_FD | crate::operation::OpMeta::FD_READ
// }
// #[cfg(unix)]
// fn cap(&self) -> i32 {
// self.res.as_raw_fd()
// }
// #[cfg(linux)]
// fn create_entry(&self) -> lio_uring::submission::Entry {
// use std::os::fd::AsRawFd;
// let buf_slice = self.buf.as_ref().unwrap().buf();
// let ptr = buf_slice.as_ptr();
// let len = buf_slice.len();
// lio_uring::operation::Read::new(
// self.res.as_raw_fd(),
// ptr.cast_mut(),
// len as u32,
// )
// .offset(self.offset as u64)
// .build()
// }
// fn run_blocking(&self) -> isize {
// use std::os::fd::AsRawFd;
// let buf_slice = self.buf.as_ref().unwrap().buf();
// let ptr = buf_slice.as_ptr();
// let len = buf_slice.len();
// syscall!(raw pread(self.res.as_raw_fd(), ptr as *mut _, len, self.offset))
// }
}