simple snappy bindings, enabling alloc free code

util/src/error.rs

@@ -65,6 +65,8 @@ pub enum UtilError {
 	SimpleString(String),
 	/// Error from a bad input size being given for the needed output.
 	BadSize,
+	/// Error from snappy.
+	Snappy(::snappy::Error),
 }
 
 impl fmt::Display for UtilError {
@@ -82,6 +84,7 @@ impl fmt::Display for UtilError {
 			UtilError::Decoder(ref err) => f.write_fmt(format_args!("{}", err)),
 			UtilError::SimpleString(ref msg) => f.write_str(&msg),
 			UtilError::BadSize => f.write_str("Bad input size."),
+			UtilError::Snappy(ref err) => f.write_fmt(format_args!("{}", err)),
 		}
 	}
 }
@@ -179,6 +182,12 @@ impl From<String> for UtilError {
 	}
 }
 
+impl From<::snappy::Error> for UtilError {
+	fn from(err: ::snappy::Error) -> UtilError {
+		UtilError::Snappy(err)
+	}
+}
+
 // TODO: uncomment below once https://github.com/rust-lang/rust/issues/27336 sorted.
 /*#![feature(concat_idents)]
 macro_rules! assimilate {