Fix off-by-one. (#243)

* Fix off-by-one.

* Fix.

Author: tomusdrw

primitive-types/impls/serde/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "impl-serde"
-version = "0.2.1"
+version = "0.2.2"
 authors = ["Parity Technologies <[email protected]>"]
 license = "Apache-2.0/MIT"
 homepage = "https://github.com/paritytech/parity-common"
@@ -11,8 +11,9 @@ serde = "1.0"
 
 [dev-dependencies]
 criterion = "0.3.0"
-uint = "0.8.1"
+serde_derive = "1.0"
 serde_json = "1.0.40"
+uint = "0.8.1"
 
 [[bench]]
 name = "impl_serde"

primitive-types/impls/serde/src/serialize.rs

@@ -105,7 +105,7 @@ pub fn deserialize<'de, D>(deserializer: D) -> Result<Vec<u8>, D::Error> where
 
 			let bytes_len = v.len() - 2;
 			let mut modulus = bytes_len % 2;
-			let mut bytes = vec![0u8; bytes_len / 2];
+			let mut bytes = vec![0u8; (bytes_len + 1) / 2];
 			let mut buf = 0;
 			let mut pos = 0;
 			for (idx, byte) in v.bytes().enumerate().skip(2) {
@@ -217,3 +217,42 @@ pub fn deserialize_check_len<'a, 'de, D>(deserializer: D, len: ExpectedLen<'a>)
 
 	deserializer.deserialize_str(Visitor { len })
 }
+
+#[cfg(test)]
+mod tests {
+	extern crate serde_derive;
+
+	use self::serde_derive::Deserialize;
+
+	#[derive(Deserialize)]
+	struct Bytes(#[serde(with="super")] Vec<u8>);
+
+	#[test]
+	fn should_not_fail_on_short_string() {
+		let a: Bytes = serde_json::from_str("\"0x\"").unwrap();
+		let b: Bytes = serde_json::from_str("\"0x1\"").unwrap();
+		let c: Bytes = serde_json::from_str("\"0x12\"").unwrap();
+		let d: Bytes = serde_json::from_str("\"0x123\"").unwrap();
+		let e: Bytes = serde_json::from_str("\"0x1234\"").unwrap();
+		let f: Bytes = serde_json::from_str("\"0x12345\"").unwrap();
+
+		assert!(a.0.is_empty());
+		assert_eq!(b.0, vec![1]);
+		assert_eq!(c.0, vec![0x12]);
+		assert_eq!(d.0, vec![0x1, 0x23]);
+		assert_eq!(e.0, vec![0x12, 0x34]);
+		assert_eq!(f.0, vec![0x1, 0x23, 0x45]);
+	}
+
+
+	#[test]
+	fn should_not_fail_on_other_strings() {
+		let a: Bytes = serde_json::from_str("\"0x7f864e18e3dd8b58386310d2fe0919eef27c6e558564b7f67f22d99d20f587\"").unwrap();
+		let b: Bytes = serde_json::from_str("\"0x7f864e18e3dd8b58386310d2fe0919eef27c6e558564b7f67f22d99d20f587b\"").unwrap();
+		let c: Bytes = serde_json::from_str("\"0x7f864e18e3dd8b58386310d2fe0919eef27c6e558564b7f67f22d99d20f587b4\"").unwrap();
+
+		assert_eq!(a.0.len(), 31);
+		assert_eq!(b.0.len(), 32);
+		assert_eq!(c.0.len(), 32);
+	}
+}