Merge 0.13.1

Author: marshallpierce

RELEASE-NOTES.md

@@ -13,6 +13,10 @@
 - `DecoderReader` now owns its inner reader, and can expose it via `into_inner()`. For symmetry, `EncoderWriter` can do the same with its writer.
 - `encoded_len` is now public so you can size encode buffers precisely.
 
+# 0.13.1
+
+- More precise decode buffer sizing, avoiding unnecessary allocation in `decode_config`.
+
 # 0.13.0
 
 - Config methods are const

src/decode.rs

@@ -95,7 +95,14 @@ pub fn decode_engine<E: Engine, T: AsRef<[u8]>>(
     input: T,
     engine: &E,
 ) -> Result<Vec<u8>, DecodeError> {
-    let mut buffer = Vec::<u8>::new();
+    let decoded_length_estimate = (input
+        .as_ref()
+        .len()
+        .checked_add(3)
+        .expect("decoded length calculation overflow"))
+        / 4
+        * 3;
+    let mut buffer = Vec::<u8>::with_capacity(decoded_length_estimate);
     decode_engine_vec(input, &mut buffer, engine).map(|_| buffer)
 }
 
@@ -340,4 +347,17 @@ mod tests {
             assert_eq!(orig_data, decode_buf);
         }
     }
+
+    #[test]
+    fn decode_engine_estimation_works_for_various_lengths() {
+        for num_prefix_quads in 0..100 {
+            for suffix in &["AA", "AAA", "AAAA"] {
+                let mut prefix = "AAAA".repeat(num_prefix_quads);
+                prefix.push_str(suffix);
+                // make sure no overflow (and thus a panic) occurs
+                let res = decode_engine(prefix, &DEFAULT_ENGINE);
+                assert!(res.is_ok());
+            }
+        }
+    }
 }