1 files changed, 91 insertions, 0 deletions
diff --git a/vendor/futures-util/src/io/read_to_end.rs b/vendor/futures-util/src/io/read_to_end.rs
new file mode 100644
index 000000000..919d7d13c
--- /dev/null
+++ b/vendor/futures-util/src/io/read_to_end.rs
@@ -0,0 +1,91 @@
+use futures_core::future::Future;
+use futures_core::ready;
+use futures_core::task::{Context, Poll};
+use futures_io::AsyncRead;
+use std::io;
+use std::pin::Pin;
+use std::vec::Vec;
+
+/// Future for the [`read_to_end`](super::AsyncReadExt::read_to_end) method.
+#[derive(Debug)]
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct ReadToEnd<'a, R: ?Sized> {
+    reader: &'a mut R,
+    buf: &'a mut Vec<u8>,
+    start_len: usize,
+}
+
+impl<R: ?Sized + Unpin> Unpin for ReadToEnd<'_, R> {}
+
+impl<'a, R: AsyncRead + ?Sized + Unpin> ReadToEnd<'a, R> {
+    pub(super) fn new(reader: &'a mut R, buf: &'a mut Vec<u8>) -> Self {
+        let start_len = buf.len();
+        Self { reader, buf, start_len }
+    }
+}
+
+struct Guard<'a> {
+    buf: &'a mut Vec<u8>,
+    len: usize,
+}
+
+impl Drop for Guard<'_> {
+    fn drop(&mut self) {
+        unsafe {
+            self.buf.set_len(self.len);
+        }
+    }
+}
+
+// This uses an adaptive system to extend the vector when it fills. We want to
+// avoid paying to allocate and zero a huge chunk of memory if the reader only
+// has 4 bytes while still making large reads if the reader does have a ton
+// of data to return. Simply tacking on an extra DEFAULT_BUF_SIZE space every
+// time is 4,500 times (!) slower than this if the reader has a very small
+// amount of data to return.
+//
+// Because we're extending the buffer with uninitialized data for trusted
+// readers, we need to make sure to truncate that if any of this panics.
+pub(super) fn read_to_end_internal<R: AsyncRead + ?Sized>(
+    mut rd: Pin<&mut R>,
+    cx: &mut Context<'_>,
+    buf: &mut Vec<u8>,
+    start_len: usize,
+) -> Poll<io::Result<usize>> {
+    let mut g = Guard { len: buf.len(), buf };
+    loop {
+        if g.len == g.buf.len() {
+            unsafe {
+                g.buf.reserve(32);
+                let capacity = g.buf.capacity();
+                g.buf.set_len(capacity);
+                super::initialize(&rd, &mut g.buf[g.len..]);
+            }
+        }
+
+        let buf = &mut g.buf[g.len..];
+        match ready!(rd.as_mut().poll_read(cx, buf)) {
+            Ok(0) => return Poll::Ready(Ok(g.len - start_len)),
+            Ok(n) => {
+                // We can't allow bogus values from read. If it is too large, the returned vec could have its length
+                // set past its capacity, or if it overflows the vec could be shortened which could create an invalid
+                // string if this is called via read_to_string.
+                assert!(n <= buf.len());
+                g.len += n;
+            }
+            Err(e) => return Poll::Ready(Err(e)),
+        }
+    }
+}
+
+impl<A> Future for ReadToEnd<'_, A>
+where
+    A: AsyncRead + ?Sized + Unpin,
+{
+    type Output = io::Result<usize>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let this = &mut *self;
+        read_to_end_internal(Pin::new(&mut this.reader), cx, this.buf, this.start_len)
+    }
+}