runtime/glue: add C++->Rust FFI glue code

Use a mutable global to hold references to the Rust runtime, and to the
C++ pseudo-Node factory function that's registered.

Use a local handle mapping to allow opaque Rust types to be
recovered.

Cargo.toml

@@ -20,6 +20,7 @@ members = [
   "experimental/split_grpc/proxy",
   "experimental/split_grpc/server",
   "oak/server/rust/oak_abi",
+  "oak/server/rust/oak_glue",
   "oak/server/rust/oak_runtime",
   "runner",
   "sdk/rust/oak",

oak/server/rust/oak_glue/BUILD

@@ -0,0 +1,58 @@
+#
+# Copyright 2019 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.
+#
+
+load("@io_bazel_rules_rust//rust:rust.bzl", "rust_library")
+load("@rules_cc//cc:defs.bzl", "cc_library")
+
+package(
+    default_visibility = ["//oak/server:__subpackages__"],
+    licenses = ["notice"],
+)
+
+rust_library(
+    name = "oak_glue",
+    srcs = glob(["src/**/*.rs"]),
+    crate_type = "staticlib",
+    edition = "2018",
+    deps = [
+        "//cargo:byteorder",
+        "//cargo:lazy_static",
+        "//cargo:log",
+        "//cargo:prost",
+        "//cargo:simple_logger",
+        "//oak/server/rust/oak_abi",
+        "//oak/server/rust/oak_runtime",
+    ],
+)
+
+# Wrapper rule to expose the resulting static library as a statically linked cc_library and
+# corresponding header so that it can be depended on by other cc_library and cc_binary rules.
+#
+# TODO: There seems to be something wrong with this rule related to caching in Bazel.
+# To reproduce:
+# - change src/lib.rs and introduce a syntax error
+# - bazel build :oak_glue_wrapper
+# - this should produce a compile error, instead Bazel is still caching the old artifact
+#
+# However, building a cc_binary target (e.g. //oak/server/dev:dev_oak_runner) does force
+# a rebuild of the Rust code.
+cc_library(
+    name = "oak_glue_wrapper",
+    srcs = [":oak_glue"],
+    hdrs = ["oak_glue.h"],
+    linkopts = ["-ldl"],
+    linkstatic = True,
+)

oak/server/rust/oak_glue/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "oak_glue"
+version = "0.1.0"
+authors = ["David Drysdale <[email protected]>"]
+edition = "2018"
+license = "Apache-2.0"
+
+[lib]
+name = "oak_glue"
+
+[dependencies]
+# Note that if new dependencies are added here:
+#  - they need to be synced to //cargo/Cargo.toml
+#  - `cd cargo && cargo raze` needs re-running, and the results checked in
+byteorder = "*"
+lazy_static = "*"
+log = { version = "*", features = ["std"] }
+oak_abi = { version = "=0.1.0" }
+oak_runtime = { version = "=0.1.0" }
+prost = "*"
+simple_logger = "*"

oak/server/rust/oak_glue/oak_glue.h

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2019 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.
+ */
+
+#ifndef OAK_SERVER_RUST_OAK_GLUE_H_
+#define OAK_SERVER_RUST_OAK_GLUE_H_
+
+#include <cstdint>
+
+extern "C" {
+
+// Perform start of day initialization.  Must only be called once, before
+// any other functions.
+void glue_init();
+
+// Function pointer used for up-calling from Rust to C++ to create and run a pseudo-Node.
+// - The data parameter has the factory_data value registered at glue_start.
+// - [name, name+name_len) gives the config name for the Node to be started.
+// - node_id should be used for all glue_<fn>() invocations by the new Node.
+// - handle is a read half of an initial channel.
+typedef void (*node_factory)(uintptr_t data, const char* name, uint32_t name_len, uint64_t node_id,
+                             uint64_t handle);
+
+// Start the Rust runtime, passing a serialized ApplicationConfiguration
+// protobuf message.
+uint64_t glue_start(const uint8_t* config_buf, uint32_t config_len, node_factory factory,
+                    uintptr_t factory_data);
+// Stop the Rust runtime.
+void glue_stop();
+
+// The following functions are analogous to those on the Oak ABI, with the
+// addition of an initial node_id parameter that identifies the Node performing
+// the operation.
+uint32_t glue_wait_on_channels(uint64_t node_id, uint8_t* buf, uint32_t count);
+uint32_t glue_channel_read(uint64_t node_id, uint64_t handle, uint8_t* buf, uint32_t size,
+                           uint32_t* actual_size, uint8_t* handle_buf, uint32_t handle_count,
+                           uint32_t* actual_handle_count);
+uint32_t glue_channel_write(uint64_t node_id, uint64_t handle, const uint8_t* buf, uint32_t size,
+                            const uint8_t* handle_buf, uint32_t handle_count);
+uint32_t glue_channel_create(uint64_t node_id, uint64_t* write, uint64_t* read);
+uint32_t glue_channel_close(uint64_t node_id, uint64_t handle);
+};
+
+#endif  // OAK_SERVER_RUST_OAK_GLUE_H_