grpc-native: Add linux support

cinterop-c/.bazelrc

@@ -1,4 +1,12 @@
-# we build the cc_static library bundled with all dependencies
 build --experimental_cc_static_library  --experimental_platform_in_output_dir
 
-build:release --compilation_mode=opt --strip=always
+build:release --compilation_mode=opt --strip=always
+
+build:macos_arm64 --platforms=@build_bazel_apple_support//platforms:macos_arm64 --apple_platform_type=macos
+build:macos_x64 --platforms=@build_bazel_apple_support//platforms:macos_x86_64 --apple_platform_type=macos
+build:ios_arm64 --platforms=@build_bazel_apple_support//platforms:ios_arm64 --apple_platform_type=ios
+build:ios_simulator_arm64 --platforms=@build_bazel_apple_support//platforms:ios_sim_arm64 --apple_platform_type=ios
+build:ios_x64 --platforms=@build_bazel_apple_support//platforms:ios_x86_64 --apple_platform_type=ios
+
+build:linux_arm64 --platforms=//platforms:linux_arm64
+build:linux_x64 --platforms=//platforms:linux_x86_64

cinterop-c/BUILD.bazel

@@ -1,11 +1,17 @@
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_file")
 load("@rules_cc//cc:defs.bzl", "cc_library")
 
-cc_library(
+cc_static_library(
     name = "kgrpc",
+    deps = [
+        ":kgrpc_lib",
+    ],
+)
+
+cc_library(
+    name = "kgrpc_lib",
     srcs = ["src/kgrpc.cpp"],
     hdrs = glob(["include/kgrpc.h"]),
-    copts = ["-std=c++20"],
     includes = ["include"],
     visibility = ["//visibility:public"],
     deps = [
@@ -24,7 +30,6 @@ cc_library(
     name = "protowire",
     srcs = ["src/protowire.cpp"],
     hdrs = glob(["include/protowire.h"]),
-    copts = ["-std=c++20"],
     includes = ["include"],
     visibility = ["//visibility:public"],
     deps = [

cinterop-c/MODULE.bazel

@@ -4,10 +4,7 @@ module(
 )
 
 # rules_cc for cc_library support
-bazel_dep(
-    name = "rules_cc",
-    version = "0.1.1",
-)
+bazel_dep(name = "rules_cc", version = "0.2.0")
 
 # required to build for apple targets (like iOS)
 bazel_dep(name = "apple_support", version = "1.22.1", repo_name = "build_bazel_apple_support")
@@ -24,9 +21,15 @@ bazel_dep(
 GRPC_VERSION = "1.74.1"
 
 ## gRPC source dependency
-
 bazel_dep(
     name = "grpc",
     version = GRPC_VERSION,
     repo_name = "com_github_grpc_grpc",
 )
+
+# Linux toolchain setup (cross-compile)
+
+register_toolchains(
+    "//toolchain:toolchain_linux_x64_konan",
+    "//toolchain:toolchain_linux_arm64_konan",
+)

cinterop-c/README.md

@@ -0,0 +1,32 @@
+This subdirectory contains the C sources required by native targets.
+It uses the Bazel build system and contains two libraries: protowire and kgrpc.
+
+### Protowire
+
+Is a thin layer over the CodedStream implementation of the C++ protobuf library. 
+To build (e.g. ios_arm64) run 
+```bash
+bazel build :protowire_fat --config=ios_arm64 --config=release
+```
+
+### KgRPC
+
+We are using the gRPC-core library, which already exports its API with a C ABI.
+Therefore, the KgRPC library is almost empty primarily used for convenient functions
+or API that is not exposed by the C API.
+
+Because the gRPC takes a while to build when compiling for multiple targets, we store 
+it as a prebuilt static (fat) in `prebuilt-deps/grpc_fat`.
+The binary can be updated by running
+```bash
+./gradlew :grpc:grpc-core:buildDependencyCLibGrpc_fat_iosArm64
+```
+
+### Compiling for Linux
+
+To produce K/N compatible static libraries, we use the Konan toolchain for compilation.
+The Bazel toolchain is specified in `toolchain/` and requires the user to specify the
+`KONAN_HOME` variable like
+```bash
+bazel build //:protowire --config=linux_arm64 --define=KONAN_HOME=$HOME/.konan/kotlin-native-prebuilt-macos-aarch64-2.2.10
+```

cinterop-c/build_target.sh

@@ -9,26 +9,28 @@ trap 'echo "ERROR: Build failed at ${BASH_SOURCE}:${LINENO}" >&2' ERR
 # Builds a static library for a specific platform (os/arch).
 #
 # Usage:
-#   ./build_target.sh //path:libtarget out_dir <platform> <short> <os>
+#   ./build_target.sh //path:libtarget dest konan_target konan_home
 # Example:
-#   ./build_target.sh :protowire_static out @build_bazel_apple_support//platforms:ios_arm64 ios_arm64 ios
+#   ./build_target.sh :protowire_static out/libprotowire_static.ios_arm64.a ios_arm64 \
+#             $HOME/.konan/kotlin-native-prebuilt-macos-aarch64-2.2.10
 #
 # The example will produce ./out/libprotowire_static.ios_arm64.a
 
 LABEL="${1:?need bazel target label}"
 DST="${2:?need output destination}"
-PLATFORM="${3:?need a platform for bazel build command}"
-OS="${4:?need the operating system of the target platform}"
+KONAN_TARGET="${3:?need the konan_target name}"
+KONAN_HOME="${4:?need the konan_home path}"
 
 CONFIG=release
 
-mkdir -p $(dirname "$DST")
+mkdir -p "$(dirname "$DST")"
 
 echo "==> Building $LABEL to $DST" >&2
-bazel build "$LABEL" --platforms="$PLATFORM" --apple_platform_type="$OS" --config="$CONFIG" --announce_rc >/dev/null
+KONAN_DEP="--define=KONAN_DEPS=/Users/johannes.zottele/.konan//dependencies"
+bazel build "$LABEL" --config="$KONAN_TARGET" --config="$CONFIG" $KONAN_DEP "--define=KONAN_HOME=$KONAN_HOME" >/dev/null
 
 # Ask Bazel what file(s) this target produced under this platform
-out="$(bazel cquery "$LABEL" --platforms="$PLATFORM" --apple_platform_type="$OS" --config="$CONFIG" --output=files | head -n1)"
+out="$(bazel cquery "$LABEL" --config="$KONAN_TARGET" --config="$CONFIG" $KONAN_DEP "--define=KONAN_HOME=$KONAN_HOME" --output=files | head -n1)"
 [[ -n "$out" ]] || { echo "No output for $LABEL ($SHORT)"; exit 1; }
 
 cp -f "$out" "$DST"

cinterop-c/platforms/BUILD.bazel

@@ -0,0 +1,15 @@
+platform(
+    name = "linux_x86_64",
+    constraint_values = [
+        "@platforms//os:linux",
+        "@platforms//cpu:x86_64",
+    ],
+)
+
+platform(
+    name = "linux_arm64",
+    constraint_values = [
+        "@platforms//os:linux",
+        "@platforms//cpu:aarch64",
+    ],
+)

cinterop-c/prebuilt-deps/grpc_fat/libgrpc_fat.linux_arm64.a.sha256

@@ -0,0 +1 @@
+5eab3ed3bebb20944f053cacf34c755173832ab65e1c7f199a5d70fb3f1e7d55

cinterop-c/prebuilt-deps/grpc_fat/libgrpc_fat.linux_x64.a.sha256

@@ -0,0 +1 @@
+511c10750585f1a7c7cd8801acaab10cf21cd8e098c381a07102496e3569b085

cinterop-c/toolchain/BUILD.bazel

@@ -0,0 +1,67 @@
+load(":cc_toolchain_config.bzl", "cc_toolchain_config")
+
+cc_toolchain_config(
+    name = "cfg_linux_x64_konan",
+    target = "linux_x64",
+)
+
+cc_toolchain_config(
+    name = "cfg_linux_arm64_konan",
+    target = "linux_arm64",
+)
+
+filegroup(
+    name = "wrappers",
+    srcs = [
+        "run_konan",
+        "run_konan_ar.sh",
+        "run_konan_clang.sh",
+        "run_konan_clangxx.sh",
+    ],
+)
+
+cc_toolchain(
+    name = "tc_linux_x64_konan",
+    all_files = ":wrappers",
+    ar_files = ":wrappers",
+    compiler_files = ":wrappers",
+    dwp_files = ":wrappers",
+    linker_files = ":wrappers",
+    objcopy_files = ":wrappers",
+    strip_files = ":wrappers",
+    toolchain_config = ":cfg_linux_x64_konan",
+    toolchain_identifier = "konan_linux_x64",
+)
+
+cc_toolchain(
+    name = "tc_linux_arm64_konan",
+    all_files = ":wrappers",
+    ar_files = ":wrappers",
+    compiler_files = ":wrappers",
+    dwp_files = ":wrappers",
+    linker_files = ":wrappers",
+    objcopy_files = ":wrappers",
+    strip_files = ":wrappers",
+    toolchain_config = ":cfg_linux_arm64_konan",
+    toolchain_identifier = "konan_linux_arm64",
+)
+
+toolchain(
+    name = "toolchain_linux_x64_konan",
+    target_compatible_with = [
+        "@platforms//os:linux",
+        "@platforms//cpu:x86_64",
+    ],
+    toolchain = ":tc_linux_x64_konan",
+    toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
+)
+
+toolchain(
+    name = "toolchain_linux_arm64_konan",
+    target_compatible_with = [
+        "@platforms//os:linux",
+        "@platforms//cpu:arm64",
+    ],
+    toolchain = ":tc_linux_arm64_konan",
+    toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
+)