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use std::convert::TryFrom;
use std::fs;
use std::io::{self, copy, sink, Read, Seek, SeekFrom};
use rustix::io::Errno;
pub enum Input<'a> {
File(fs::File),
Stdin(io::StdinLock<'a>),
}
impl<'a> Read for Input<'a> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
match *self {
Input::File(ref mut file) => file.read(buf),
Input::Stdin(ref mut stdin) => stdin.read(buf),
}
}
}
impl<'a> Seek for Input<'a> {
fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
fn try_skip<R>(reader: R, pos: SeekFrom, err_desc: &'static str) -> io::Result<u64>
where
R: Read,
{
let cant_seek_abs_err = || Err(io::Error::new(io::ErrorKind::Other, err_desc));
let offset = match pos {
SeekFrom::Current(o) => u64::try_from(o).or_else(|_e| cant_seek_abs_err())?,
SeekFrom::Start(_) | SeekFrom::End(_) => cant_seek_abs_err()?,
};
copy(&mut reader.take(offset), &mut sink())
}
match *self {
Input::File(ref mut file) => {
let seek_res = file.seek(pos);
if let Err(Some(Errno::SPIPE)) = seek_res.as_ref().map_err(Errno::from_io_error) {
try_skip(
file,
pos,
"Pipes only support seeking forward with a relative offset",
)
} else {
seek_res
}
}
Input::Stdin(ref mut stdin) => try_skip(
stdin,
pos,
"STDIN only supports seeking forward with a relative offset",
),
}
}
}
impl<'a> Input<'a> {
pub fn into_inner(self) -> Box<dyn Read + 'a> {
match self {
Input::File(file) => Box::new(file),
Input::Stdin(stdin) => Box::new(stdin),
}
}
}
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