feat: add rust-protobuf support to extism-convert (#653)

(code from @zshipko, thank you!)

---------

Co-authored-by: Zach Shipko <zach@dylibso.com>

convert/Cargo.toml

@@ -14,6 +14,7 @@ anyhow = "1.0.75"
 base64 = "~0.21"
 bytemuck = {version = "1.14.0", optional = true }
 prost = { version = "0.12.0", optional = true }
+protobuf = { version = "3.2.0", optional = true }
 rmp-serde = { version = "1.1.2", optional = true }
 serde = "1.0.186"
 serde_json = "1.0.105"
@@ -22,7 +23,6 @@ serde_json = "1.0.105"
 serde = { version = "1.0.186", features = ["derive"] }
 
 [features]
-default = ["msgpack", "protobuf", "raw"]
+default = ["msgpack", "prost", "raw"]
 msgpack = ["rmp-serde"]
-protobuf = ["prost"]
 raw = ["bytemuck"]

convert/src/encoding.rs

@@ -112,19 +112,19 @@ impl FromBytesOwned for Base64<String> {
 /// Protobuf encoding
 ///
 /// Allows for `prost` Protobuf messages to be used as arguments to Extism plugin calls
-#[cfg(feature = "protobuf")]
+#[cfg(feature = "prost")]
 #[derive(Debug)]
-pub struct Protobuf<T: prost::Message>(pub T);
+pub struct Prost<T: prost::Message>(pub T);
 
-#[cfg(feature = "protobuf")]
-impl<T: prost::Message> From<T> for Protobuf<T> {
+#[cfg(feature = "prost")]
+impl<T: prost::Message> From<T> for Prost<T> {
     fn from(data: T) -> Self {
         Self(data)
     }
 }
 
-#[cfg(feature = "protobuf")]
-impl<'a, T: prost::Message> ToBytes<'a> for Protobuf<T> {
+#[cfg(feature = "prost")]
+impl<'a, T: prost::Message> ToBytes<'a> for Prost<T> {
     type Bytes = Vec<u8>;
 
     fn to_bytes(&self) -> Result<Self::Bytes, Error> {
@@ -132,10 +132,32 @@ impl<'a, T: prost::Message> ToBytes<'a> for Protobuf<T> {
     }
 }
 
-#[cfg(feature = "protobuf")]
-impl<T: Default + prost::Message> FromBytesOwned for Protobuf<T> {
+#[cfg(feature = "prost")]
+impl<T: Default + prost::Message> FromBytesOwned for Prost<T> {
     fn from_bytes_owned(data: &[u8]) -> Result<Self, Error> {
-        Ok(Protobuf(T::decode(data)?))
+        Ok(Prost(T::decode(data)?))
+    }
+}
+
+/// Protobuf encoding
+///
+/// Allows for `rust-protobuf` Protobuf messages to be used as arguments to Extism plugin calls
+#[cfg(feature = "protobuf")]
+pub struct Protobuf<T: protobuf::Message>(pub T);
+
+#[cfg(feature = "protobuf")]
+impl<'a, T: protobuf::Message> ToBytes<'a> for Protobuf<T> {
+    type Bytes = Vec<u8>;
+
+    fn to_bytes(&self) -> Result<Self::Bytes, Error> {
+        Ok(self.0.write_to_bytes()?)
+    }
+}
+
+#[cfg(feature = "protobuf")]
+impl<T: Default + protobuf::Message> FromBytesOwned for Protobuf<T> {
+    fn from_bytes_owned(data: &[u8]) -> Result<Self, Error> {
+        Ok(Protobuf(T::parse_from_bytes(data)?))
     }
 }
 

convert/src/lib.rs

@@ -18,6 +18,9 @@ pub use encoding::{Base64, Json};
 #[cfg(feature = "msgpack")]
 pub use encoding::Msgpack;
 
+#[cfg(feature = "prost")]
+pub use encoding::Prost;
+
 #[cfg(feature = "protobuf")]
 pub use encoding::Protobuf;