openpgp: Don't try to fill the buffer if we reached the end.

  - Previously, when the read exceeded the buffered data, we tried to
    fill the buffer even if we reached the last chunk.  Then, we would
    allocate a new buffer and copy the data over, only to later
    realize that we reached the last chunk and the current chunk is
    exhausted.

1 files changed, 6 insertions, 0 deletions

diff --git a/openpgp/src/parse/partial_body.rs b/openpgp/src/parse/partial_body.rs
index 1bd4e863..4f72c5d2 100644
--- a/openpgp/src/parse/partial_body.rs
+++ b/openpgp/src/parse/partial_body.rs
@@ -95,6 +95,12 @@ impl<T: BufferedReader<Cookie>> BufferedReaderPartialBodyFilter<T> {
                       amount, self.partial_body_length, self.last);
         }
 
+        if self.last && self.partial_body_length == 0 {
+            // We reached the end.  Avoid fruitlessly copying data
+            // over and over again trying to buffer more data.
+            return Ok(());
+        }
+
         // We want to avoid double buffering as much as possible.
         // Thus, we only buffer as much as needed.
         let mut buffer = self.unused_buffers.pop()