1 files changed, 106 insertions, 0 deletions
diff --git a/third_party/rust/bhttp/src/rw.rs b/third_party/rust/bhttp/src/rw.rs
new file mode 100644
index 0000000000..8fee16daa9
--- /dev/null
+++ b/third_party/rust/bhttp/src/rw.rs
@@ -0,0 +1,106 @@
+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)
+    }
+}