1 files changed, 151 insertions, 0 deletions
diff --git a/third_party/rust/hyper/src/common/buf.rs b/third_party/rust/hyper/src/common/buf.rs
new file mode 100644
index 0000000000..64e9333ead
--- /dev/null
+++ b/third_party/rust/hyper/src/common/buf.rs
@@ -0,0 +1,151 @@
+use std::collections::VecDeque;
+use std::io::IoSlice;
+
+use bytes::{Buf, BufMut, Bytes, BytesMut};
+
+pub(crate) struct BufList<T> {
+    bufs: VecDeque<T>,
+}
+
+impl<T: Buf> BufList<T> {
+    pub(crate) fn new() -> BufList<T> {
+        BufList {
+            bufs: VecDeque::new(),
+        }
+    }
+
+    #[inline]
+    pub(crate) fn push(&mut self, buf: T) {
+        debug_assert!(buf.has_remaining());
+        self.bufs.push_back(buf);
+    }
+
+    #[inline]
+    #[cfg(feature = "http1")]
+    pub(crate) fn bufs_cnt(&self) -> usize {
+        self.bufs.len()
+    }
+}
+
+impl<T: Buf> Buf for BufList<T> {
+    #[inline]
+    fn remaining(&self) -> usize {
+        self.bufs.iter().map(|buf| buf.remaining()).sum()
+    }
+
+    #[inline]
+    fn chunk(&self) -> &[u8] {
+        self.bufs.front().map(Buf::chunk).unwrap_or_default()
+    }
+
+    #[inline]
+    fn advance(&mut self, mut cnt: usize) {
+        while cnt > 0 {
+            {
+                let front = &mut self.bufs[0];
+                let rem = front.remaining();
+                if rem > cnt {
+                    front.advance(cnt);
+                    return;
+                } else {
+                    front.advance(rem);
+                    cnt -= rem;
+                }
+            }
+            self.bufs.pop_front();
+        }
+    }
+
+    #[inline]
+    fn chunks_vectored<'t>(&'t self, dst: &mut [IoSlice<'t>]) -> usize {
+        if dst.is_empty() {
+            return 0;
+        }
+        let mut vecs = 0;
+        for buf in &self.bufs {
+            vecs += buf.chunks_vectored(&mut dst[vecs..]);
+            if vecs == dst.len() {
+                break;
+            }
+        }
+        vecs
+    }
+
+    #[inline]
+    fn copy_to_bytes(&mut self, len: usize) -> Bytes {
+        // Our inner buffer may have an optimized version of copy_to_bytes, and if the whole
+        // request can be fulfilled by the front buffer, we can take advantage.
+        match self.bufs.front_mut() {
+            Some(front) if front.remaining() == len => {
+                let b = front.copy_to_bytes(len);
+                self.bufs.pop_front();
+                b
+            }
+            Some(front) if front.remaining() > len => front.copy_to_bytes(len),
+            _ => {
+                assert!(len <= self.remaining(), "`len` greater than remaining");
+                let mut bm = BytesMut::with_capacity(len);
+                bm.put(self.take(len));
+                bm.freeze()
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::ptr;
+
+    use super::*;
+
+    fn hello_world_buf() -> BufList<Bytes> {
+        BufList {
+            bufs: vec![Bytes::from("Hello"), Bytes::from(" "), Bytes::from("World")].into(),
+        }
+    }
+
+    #[test]
+    fn to_bytes_shorter() {
+        let mut bufs = hello_world_buf();
+        let old_ptr = bufs.chunk().as_ptr();
+        let start = bufs.copy_to_bytes(4);
+        assert_eq!(start, "Hell");
+        assert!(ptr::eq(old_ptr, start.as_ptr()));
+        assert_eq!(bufs.chunk(), b"o");
+        assert!(ptr::eq(old_ptr.wrapping_add(4), bufs.chunk().as_ptr()));
+        assert_eq!(bufs.remaining(), 7);
+    }
+
+    #[test]
+    fn to_bytes_eq() {
+        let mut bufs = hello_world_buf();
+        let old_ptr = bufs.chunk().as_ptr();
+        let start = bufs.copy_to_bytes(5);
+        assert_eq!(start, "Hello");
+        assert!(ptr::eq(old_ptr, start.as_ptr()));
+        assert_eq!(bufs.chunk(), b" ");
+        assert_eq!(bufs.remaining(), 6);
+    }
+
+    #[test]
+    fn to_bytes_longer() {
+        let mut bufs = hello_world_buf();
+        let start = bufs.copy_to_bytes(7);
+        assert_eq!(start, "Hello W");
+        assert_eq!(bufs.remaining(), 4);
+    }
+
+    #[test]
+    fn one_long_buf_to_bytes() {
+        let mut buf = BufList::new();
+        buf.push(b"Hello World" as &[_]);
+        assert_eq!(buf.copy_to_bytes(5), "Hello");
+        assert_eq!(buf.chunk(), b" World");
+    }
+
+    #[test]
+    #[should_panic(expected = "`len` greater than remaining")]
+    fn buf_to_bytes_too_many() {
+        hello_world_buf().copy_to_bytes(42);
+    }
+}