Build oak_proto_rust for bare metal with Bazel.

BUG: 340185565
Change-Id: Iae5cef128b32e549a50991764fdb6fa60e2a2f92

justfile

@@ -172,7 +172,7 @@ kokoro_run_tests: all_ensure_no_std
 clang-tidy:
     bazel build $BAZEL_CONFIG_FLAG --config=clang-tidy //cc/...
 
-bare_metal_crates := "//oak_linux_boot_params //oak_channel //oak_core //oak_virtio //third_party/rust-hypervisor-firmware-virtio //micro_rpc"
+bare_metal_crates := "//oak_linux_boot_params //oak_channel //oak_core //oak_virtio //third_party/rust-hypervisor-firmware-virtio //micro_rpc //oak_proto_rust"
 
 bazel-ci:
     bazel build --config=unsafe-fast-presubmit -- @jemalloc //...:all

micro_rpc/BUILD

@@ -64,5 +64,6 @@ cargo_build_script(
     ],
     deps = [
         "//micro_rpc_build",
+        "//oak_proto_build_utils",
     ],
 )

micro_rpc/build.rs

@@ -14,9 +14,6 @@
 // limitations under the License.
 //
 
-#[cfg(feature = "bazel")]
-use std::fs;
-
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     micro_rpc_build::compile(
         &["../proto/micro_rpc/messages.proto"],
@@ -25,41 +22,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     );
 
     #[cfg(feature = "bazel")]
-    fix_prost_derives()?;
-
-    Ok(())
-}
-
-#[cfg(feature = "bazel")]
-/// Replaces refs to prost with prost_derive. See b/340185847.
-/// Only to be called from build scripts of crates that generate prost code.
-/// Only to be called when building with Bazel.
-/// The issue that this fixes is that prost with "derive" feature uses
-/// "prost-derive", which requires std. In Cargo, that works OK as the
-/// feature "std" isn't propagated to deps of crates that don't use them,
-/// but Bazel's can't handle that. With Bazel, if we bring prost-derive
-/// into the index, it'll make deps like `bytes` also use the "std" feature.
-/// Take into account that in Cargo, features of dependencies are declared in
-/// the "depending" crate, that is, they belong to the dependency arc, while
-/// in Bazel, one crate is brought into an index with a fixed set of features.
-/// To solve this, and to be able to build for bare metal from Bazel, we
-/// import prost without derive to oak_no_std_crates_index, use prost-derive
-/// derive macro directly, but we need to change the crate name, as we no
-/// longer have prost re-exporting the derive macros.
-pub fn fix_prost_derives() -> Result<(), Box<dyn std::error::Error>> {
-    // let out_dir_path = std::path::PathBuf::from(std::env::var("OUT_DIR"))?;
-
-    let out_dir = std::env::var("OUT_DIR")?;
-    for entry in fs::read_dir(&out_dir)? {
-        let file_path = entry?.path();
-        let contents = fs::read_to_string(&file_path)?;
-
-        let updated = contents.replace("::prost::Message", "::prost_derive::Message");
-        let updated = updated.replace("::prost::Oneof", "::prost_derive::Oneof");
-        let updated = updated.replace("::prost::Enumeration", "::prost_derive::Enumeration");
-
-        fs::write(&file_path, updated)?;
-    }
+    oak_proto_build_utils::fix_prost_derives()?;
 
     Ok(())
 }

oak_channel/BUILD

@@ -26,7 +26,6 @@ rust_library(
     srcs = glob(["src/**"]),
     deps = [
         "//oak_core",
-        # "@oak_crates_index//:anyhow",
         "@oak_crates_index//:static_assertions",
     ] + select({
         "@platforms//os:none": [

oak_proto_build_utils/BUILD

@@ -0,0 +1,30 @@
+#
+# Copyright 2024 The Project Oak Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# This package provides build utils for protos. At the moment this is only
+# used from Bazel therefore not present in Cargo workspaces.
+
+load("@rules_rust//rust:defs.bzl", "rust_library")
+
+package(
+    default_visibility = ["//visibility:public"],
+    licenses = ["notice"],
+)
+
+rust_library(
+    name = "oak_proto_build_utils",
+    srcs = glob(["src/**"]),
+)

oak_proto_build_utils/src/lib.rs

@@ -0,0 +1,48 @@
+// Copyright 2024 The Project Oak Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::fs;
+
+/// Replaces refs to prost with prost_derive. See b/340185847.
+/// Only to be called from build scripts of crates that generate prost code.
+/// Only to be called when building with Bazel.
+/// The issue that this fixes is that prost with "derive" feature uses
+/// "prost-derive", which requires std. In Cargo, that works OK as the
+/// feature "std" isn't propagated to deps of crates that don't use them,
+/// but Bazel's can't handle that. With Bazel, if we bring prost-derive
+/// into the index, it'll make deps like `bytes` also use the "std" feature.
+/// Take into account that in Cargo, features of dependencies are declared in
+/// the "depending" crate, that is, they belong to the dependency arc, while
+/// in Bazel, one crate is brought into an index with a fixed set of features.
+/// To solve this, and to be able to build for bare metal from Bazel, we
+/// import prost without derive to oak_no_std_crates_index, use prost-derive
+/// derive macro directly, but we need to change the crate name, as we no
+/// longer have prost re-exporting the derive macros.
+pub fn fix_prost_derives() -> Result<(), Box<dyn std::error::Error>> {
+    // let out_dir_path = std::path::PathBuf::from(std::env::var("OUT_DIR"))?;
+
+    let out_dir = std::env::var("OUT_DIR")?;
+    for entry in fs::read_dir(&out_dir)? {
+        let file_path = entry?.path();
+        let contents = fs::read_to_string(&file_path)?;
+
+        let updated = contents.replace("::prost::Message", "::prost_derive::Message");
+        let updated = updated.replace("::prost::Oneof", "::prost_derive::Oneof");
+        let updated = updated.replace("::prost::Enumeration", "::prost_derive::Enumeration");
+
+        fs::write(&file_path, updated)?;
+    }
+
+    Ok(())
+}

oak_proto_rust/BUILD

@@ -25,12 +25,23 @@ package(
 rust_library(
     name = "oak_proto_rust",
     srcs = glob(["src/**"]),
+    proc_macro_deps = [
+        "@oak_crates_index//:prost-derive",
+    ],
     deps = [
         ":build",
         "//micro_rpc",
-        "@oak_crates_index//:prost",
-        "@oak_crates_index//:prost-types",
-    ],
+    ] + select({
+        "@platforms//os:none": [
+            "//third_party/prost-types",
+            "@oak_no_std_crates_index//:prost",
+        ],
+        "//conditions:default": [
+            # See comment on micro_rpc/BUILD.
+            "@oak_crates_index//:prost",
+            "@oak_crates_index//:prost-types",
+        ],
+    }),
 )
 
 cargo_build_script(
@@ -41,6 +52,7 @@ cargo_build_script(
     build_script_env = {
         "PROTOC": "$(execpath @com_google_protobuf//:protoc)",
     },
+    crate_features = ["bazel"],  # See b/340185847 and fix_prost_derives function doc.
     data = [
         "//proto:digest_proto",
         "//proto/attestation:attachment_proto",
@@ -54,16 +66,18 @@ cargo_build_script(
         "//proto/attestation:verification_proto",
         "//proto/containers:interfaces_proto",
         "//proto/crypto:crypto_proto",
-        "//proto/crypto:crypto_rust_prost",
         "//proto/oak_functions:abi_proto",
         "//proto/oak_functions:lookup_data_proto",
         "//proto/oak_functions:testing_proto",
         "//proto/oak_functions/service:oak_functions_proto",
         "//proto/session:session_proto",
+    ],
+    tools = [
         "@com_google_protobuf//:protoc",
     ],
     deps = [
         "//micro_rpc_build",
+        "//oak_proto_build_utils",
         "@oak_crates_index//:prost-build",
     ],
 )

oak_proto_rust/build.rs

@@ -92,5 +92,8 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         println!("cargo:rerun-if-changed={}", proto_path);
     }
 
+    #[cfg(feature = "bazel")]
+    oak_proto_build_utils::fix_prost_derives()?;
+
     Ok(())
 }

proto/crypto/BUILD

@@ -15,7 +15,6 @@
 #
 
 load("@bazel_skylib//rules:build_test.bzl", "build_test")
-load("@rules_rust//proto/prost:defs.bzl", "rust_prost_library")
 
 package(
     default_visibility = ["//visibility:public"],
@@ -37,11 +36,6 @@ java_proto_library(
     deps = [":crypto_proto"],
 )
 
-rust_prost_library(
-    name = "crypto_rust_prost",
-    proto = ":crypto_proto",
-)
-
 build_test(
     name = "build_test",
     targets = [

third_party/prost-types/BUILD

@@ -0,0 +1,40 @@
+#
+# Copyright 2024 The Project Oak Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# Upstream prost-types depends on prost-derive unconditionally, which means
+# we can't use it in our oak_no_std_crates_index.
+
+load("@rules_rust//rust:defs.bzl", "rust_library")
+
+package(
+    default_visibility = ["//visibility:public"],
+)
+
+rust_library(
+    name = "prost-types",
+    srcs = glob(["src/**"]),
+    proc_macro_deps = [
+        "@oak_crates_index//:prost-derive",
+    ],
+    deps = select({
+        "@platforms//os:none": [
+            "@oak_no_std_crates_index//:prost",
+        ],
+        "//conditions:default": [
+            "@oak_crates_index//:prost",
+        ],
+    }),
+)

third_party/prost-types/Cargo.toml

@@ -0,0 +1,29 @@
+[package]
+name = "prost-types"
+version = "0.12.6"
+authors = [
+  "Dan Burkert <[email protected]>",
+  "Lucio Franco <[email protected]>",
+  "Casper Meijn <[email protected]>",
+  "Tokio Contributors <[email protected]>",
+]
+license = "Apache-2.0"
+repository = "https://github.com/tokio-rs/prost"
+documentation = "https://docs.rs/prost-types"
+readme = "README.md"
+description = "Prost definitions of Protocol Buffers well known types."
+edition = "2021"
+rust-version = "1.70"
+
+[lib]
+doctest = false
+
+[features]
+default = ["std"]
+std = ["prost/std"]
+
+[dependencies]
+prost = { version = "0.12.6", path = "../prost", default-features = false, features = ["prost-derive"] }
+
+[dev-dependencies]
+proptest = "1"