Implement conformance test binary

Cargo.toml

@@ -13,6 +13,7 @@ members = [
     "protobuf-examples/issue-614",
     "protobuf-parse",
     "protobuf-support",
+    "test-crates/conformance",
     "test-crates/perftest/bytes",
     "test-crates/perftest/misc",
     "test-crates/perftest/vs-cxx",

test-crates/conformance/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "conformance"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+anyhow = "1.0.68"
+protobuf = { path = "../../protobuf" }
+protobuf-json-mapping = { version = "4.0.0-alpha.0", path = "../../protobuf-json-mapping" }
+
+[build-dependencies]
+protobuf-codegen = { path = "../../protobuf-codegen" }

test-crates/conformance/build.rs

@@ -0,0 +1,7 @@
+fn main() {
+    protobuf_codegen::Codegen::new()
+        .includes(["../../google-protobuf-all-protos/protobuf/protobuf-git/conformance", "../../google-protobuf-all-protos/protobuf/protobuf-git/src/google/protobuf"])
+        .inputs(["../../google-protobuf-all-protos/protobuf/protobuf-git/conformance/conformance.proto", "../../google-protobuf-all-protos/protobuf/protobuf-git/src/google/protobuf/test_messages_proto2.proto", "../../google-protobuf-all-protos/protobuf/protobuf-git/src/google/protobuf/test_messages_proto3.proto"])
+        .cargo_out_dir("protos")
+        .run_from_script();
+}

test-crates/conformance/src/main.rs

@@ -0,0 +1,113 @@
+use std::io::{self, Read, Write};
+
+use anyhow::{anyhow, bail, Context, Error, Result};
+
+mod protos {
+    include!(concat!(env!("OUT_DIR"), "/protos/mod.rs"));
+}
+
+use protobuf::Message;
+use protos::conformance::{
+    conformance_request::Payload, ConformanceRequest, ConformanceResponse, WireFormat,
+};
+
+fn main() {
+    loop {
+        match serve_conformance_request() {
+            Ok(false) => {}
+            Ok(true) => break,
+            Err(e) => {
+                eprintln!("{:#}", e);
+                std::process::exit(1)
+            }
+        }
+    }
+}
+
+fn serve_conformance_request() -> Result<bool> {
+    let mut stdin = io::stdin().lock();
+    let mut len = [0; 4];
+    match stdin.read_exact(&mut len) {
+        Ok(()) => {}
+        Err(ref e) if e.kind() == io::ErrorKind::UnexpectedEof => {
+            return Ok(true);
+        }
+        Err(e) => return Err(Error::new(e).context("reading request length")),
+    }
+    let len = u32::from_le_bytes(len);
+    let mut buf = vec![0; len as usize];
+    stdin.read_exact(&mut buf).context("reading request")?;
+
+    let request = ConformanceRequest::parse_from_bytes(&buf).context("parsing request")?;
+
+    let response = run_test(&request).context("running test")?;
+
+    let response = response.write_to_bytes().context("serializing response")?;
+    io::stdout()
+        .write_all(&response)
+        .context("writing response")?;
+
+    Ok(false)
+}
+
+fn run_test(request: &ConformanceRequest) -> Result<ConformanceResponse> {
+    let files = [
+        protos::test_messages_proto3::file_descriptor(),
+        protos::test_messages_proto2::file_descriptor(),
+    ];
+    let descriptor = files
+        .into_iter()
+        .flat_map(|file| file.message_by_full_name(&request.message_type))
+        .next()
+        .ok_or_else(|| anyhow!("couldn't find message type {}", request.message_type))?;
+
+    let Some(ref payload) = request.payload else { bail!("missing or unsupported payload"); };
+
+    let mut test_message = descriptor.new_instance();
+    let mut response = ConformanceResponse::new();
+    match *payload {
+        Payload::ProtobufPayload(ref payload) => {
+            if let Err(e) = test_message.merge_from_bytes_dyn(payload) {
+                response.set_parse_error(e.to_string());
+            }
+        }
+        Payload::JsonPayload(ref payload) => {
+            if let Err(e) = protobuf_json_mapping::merge_from_str(&mut *test_message, payload) {
+                response.set_parse_error(e.to_string());
+            }
+        }
+        Payload::JspbPayload(_) => {
+            response.set_skipped("JSPB input not supported".into());
+        }
+        Payload::TextPayload(ref payload) => {
+            if let Err(e) = protobuf::text_format::merge_from_str(&mut *test_message, payload) {
+                response.set_parse_error(e.to_string());
+            }
+        }
+    }
+
+    let requested_output_format = request
+        .requested_output_format
+        .enum_value()
+        .map_err(|i| anyhow!("unknown wire format {}", i))?;
+    match requested_output_format {
+        WireFormat::UNSPECIFIED => bail!("unspecified output format"),
+        WireFormat::PROTOBUF => response.set_protobuf_payload(
+            test_message
+                .write_to_bytes_dyn()
+                .context("serializing test message")?,
+        ),
+        WireFormat::JSON => {
+            response.set_json_payload(
+                protobuf_json_mapping::print_to_string(&*test_message)
+                    .context("serializing test message as JSON")?,
+            );
+        }
+        WireFormat::JSPB => response.set_skipped("JSPB output not supported".into()),
+        WireFormat::TEXT_FORMAT => {
+            response.set_text_payload(protobuf::text_format::print_to_string(&*test_message))
+        }
+    }
+
+    Ok(response)
+}