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use crate::err::Res;
#[cfg(feature = "read-bhttp")]
use crate::{err::Error, ReadSeek};
#[cfg(feature = "read-bhttp")]
use std::borrow::BorrowMut;
use std::{convert::TryFrom, io};
#[cfg(feature = "write-bhttp")]
#[allow(clippy::cast_possible_truncation)]
fn write_uint(n: u8, v: impl Into<u64>, w: &mut impl io::Write) -> Res<()> {
let v = v.into();
assert!(n > 0 && usize::from(n) < std::mem::size_of::<u64>());
for i in 0..n {
w.write_all(&[((v >> (8 * (n - i - 1))) & 0xff) as u8])?;
}
Ok(())
}
#[cfg(feature = "write-bhttp")]
pub fn write_varint(v: impl Into<u64>, w: &mut impl io::Write) -> Res<()> {
let v = v.into();
match () {
_ if v < (1 << 6) => write_uint(1, v, w),
_ if v < (1 << 14) => write_uint(2, v | (1 << 14), w),
_ if v < (1 << 30) => write_uint(4, v | (2 << 30), w),
_ if v < (1 << 62) => write_uint(8, v | (3 << 62), w),
_ => panic!("Varint value too large"),
}
}
#[cfg(feature = "write-bhttp")]
pub fn write_len(len: usize, w: &mut impl io::Write) -> Res<()> {
write_varint(u64::try_from(len).unwrap(), w)
}
#[cfg(feature = "write-bhttp")]
pub fn write_vec(v: &[u8], w: &mut impl io::Write) -> Res<()> {
write_len(v.len(), w)?;
w.write_all(v)?;
Ok(())
}
#[cfg(feature = "read-bhttp")]
fn read_uint<T, R>(n: usize, r: &mut T) -> Res<Option<u64>>
where
T: BorrowMut<R> + ?Sized,
R: ReadSeek + ?Sized,
{
let mut buf = [0; 7];
let count = r.borrow_mut().read(&mut buf[..n])?;
if count == 0 {
return Ok(None);
} else if count < n {
return Err(Error::Truncated);
}
let mut v = 0;
for i in &buf[..n] {
v = (v << 8) | u64::from(*i);
}
Ok(Some(v))
}
#[cfg(feature = "read-bhttp")]
pub fn read_varint<T, R>(r: &mut T) -> Res<Option<u64>>
where
T: BorrowMut<R> + ?Sized,
R: ReadSeek + ?Sized,
{
if let Some(b1) = read_uint(1, r)? {
Ok(Some(match b1 >> 6 {
0 => b1 & 0x3f,
1 => ((b1 & 0x3f) << 8) | read_uint(1, r)?.ok_or(Error::Truncated)?,
2 => ((b1 & 0x3f) << 24) | read_uint(3, r)?.ok_or(Error::Truncated)?,
3 => ((b1 & 0x3f) << 56) | read_uint(7, r)?.ok_or(Error::Truncated)?,
_ => unreachable!(),
}))
} else {
Ok(None)
}
}
#[cfg(feature = "read-bhttp")]
pub fn read_vec<T, R>(r: &mut T) -> Res<Option<Vec<u8>>>
where
T: BorrowMut<R> + ?Sized,
R: ReadSeek + ?Sized,
{
use std::io::SeekFrom;
if let Some(len) = read_varint(r)? {
// Check that the input contains enough data. Before allocating.
let r = r.borrow_mut();
let pos = r.stream_position()?;
let end = r.seek(SeekFrom::End(0))?;
if end - pos < len {
return Err(Error::Truncated);
}
let _ = r.seek(SeekFrom::Start(pos))?;
let mut v = vec![0; usize::try_from(len)?];
r.read_exact(&mut v)?;
Ok(Some(v))
} else {
Ok(None)
}
}