rust: add Proxy-WASM for Rust (MVP).

Signed-off-by: Piotr Sikora <piotrsikora@google.com>

.gitignore

@@ -22,3 +22,4 @@ TAGS
 .vimrc
 .vs
 .vscode
+**/Cargo.lock

api/wasm/cpp/Makefile.base

@@ -1,13 +1,13 @@
-API:=$(shell git rev-parse --show-toplevel)/api/wasm/cpp
+CPP_API:=$(shell git rev-parse --show-toplevel)/api/wasm/cpp
 
 ifdef NO_CONTEXT
   CONTEXT_LIB =
 else
-  CONTEXT_LIB = ${API}/proxy_wasm_intrinsics.cc
+  CONTEXT_LIB = ${CPP_API}/proxy_wasm_intrinsics.cc
 endif
 
-%.wasm %.wat: %.cc ${API}/proxy_wasm_intrinsics.h ${API}/proxy_wasm_intrinsics.js
-	em++ -s WASM=1 -s LEGALIZE_JS_FFI=0 -s EMIT_EMSCRIPTEN_METADATA=1 --std=c++17 -O3 -g3 -I${API} --js-library ${API}/proxy_wasm_intrinsics.js $*.cc ${CONTEXT_LIB} -o $*.js
+%.wasm %.wat: %.cc ${CPP_API}/proxy_wasm_intrinsics.h ${CPP_API}/proxy_wasm_intrinsics.js
+	em++ -s WASM=1 -s LEGALIZE_JS_FFI=0 -s EMIT_EMSCRIPTEN_METADATA=1 --std=c++17 -O3 -g3 -I${CPP_API} --js-library ${CPP_API}/proxy_wasm_intrinsics.js $*.cc ${CONTEXT_LIB} -o $*.js
 	wavm-disas $*.wasm $*.wat
 	wavm-compile $*.wasm $*.wasm
 	rm -f $*.js $*.wast

api/wasm/rust/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+description = "Proxy-WASM for Rust"
+name = "proxy_wasm"
+version = "0.0.1"
+authors = ["Piotr Sikora <piotrsikora@google.com>"]
+edition = "2018"
+
+[dependencies]
+log = "0.4"
+
+[profile.release]
+lto = true
+opt-level = 3
+panic = "abort"

api/wasm/rust/Makefile.base

@@ -0,0 +1,9 @@
+RUST_API:=$(shell git rev-parse --show-toplevel)/api/wasm/rust
+
+%.wasm %.wat: %/src/lib.rs %/Cargo.toml ${RUST_API}/src/lib.rs ${RUST_API}/Cargo.toml
+	cd $* && cargo build --target=wasm32-unknown-unknown --release
+	mv $*/target/wasm32-unknown-unknown/release/$*.wasm .
+	rm -rf $*/target
+	wasm-gc $*.wasm
+	wavm-disas $*.wasm $*.wat
+	chmod 644 $*.wat

api/wasm/rust/src/lib.rs

@@ -0,0 +1,72 @@
+/// Logger that integrates with host's logging system.
+pub struct Logger;
+
+static LOGGER: Logger = Logger;
+
+impl Logger {
+    pub fn init() -> Result<(), log::SetLoggerError> {
+        log::set_logger(&LOGGER).map(|()| log::set_max_level(log::LevelFilter::Trace))
+    }
+
+    fn proxywasm_loglevel(level: log::Level) -> u32 {
+        match level {
+            log::Level::Trace => 0,
+            log::Level::Debug => 1,
+            log::Level::Info => 2,
+            log::Level::Warn => 3,
+            log::Level::Error => 4,
+        }
+    }
+}
+
+impl log::Log for Logger {
+    fn enabled(&self, _metadata: &log::Metadata) -> bool {
+        true
+    }
+
+    fn log(&self, record: &log::Record) {
+        let level = Logger::proxywasm_loglevel(record.level());
+        let message = record.args().to_string();
+        unsafe {
+            host::proxy_log(level, message.as_ptr(), message.len());
+        }
+    }
+
+    fn flush(&self) {}
+}
+
+/// Always hook into host's logging system.
+#[no_mangle]
+fn __post_instantiate() {
+    Logger::init().unwrap();
+}
+
+/// Allow host to allocate memory.
+#[no_mangle]
+fn _malloc(size: usize) -> *mut u8 {
+    let mut vec: Vec<u8> = Vec::with_capacity(size);
+    unsafe {
+        vec.set_len(size);
+    }
+    let slice = vec.into_boxed_slice();
+    Box::into_raw(slice) as *mut u8
+}
+
+/// Allow host to free memory.
+// TODO(PiotrSikora): make sure ptr is within acceptable range.
+#[no_mangle]
+fn _free(ptr: *mut u8) {
+    if !ptr.is_null() {
+        unsafe {
+            Box::from_raw(ptr);
+        }
+    }
+}
+
+/// Low-level Proxy-WASM APIs for the host functions.
+pub mod host {
+    extern "C" {
+        #[link_name = "_proxy_log"]
+        pub fn proxy_log(level: u32, message_data: *const u8, message_size: usize);
+    }
+}

test/extensions/wasm/test_data/Makefile

@@ -1,5 +1,6 @@
 NO_CONTEXT = true
 
-all: logging_cpp.wasm bad_signature_cpp.wasm segv_cpp.wasm emscripten_cpp.wasm asm2wasm_cpp.wasm
+all: logging_cpp.wasm logging_rust.wasm bad_signature_cpp.wasm segv_cpp.wasm emscripten_cpp.wasm asm2wasm_cpp.wasm
 
 include ../../../../api/wasm/cpp/Makefile.base
+include ../../../../api/wasm/rust/Makefile.base

test/extensions/wasm/test_data/logging_cpp.cc

@@ -8,10 +8,11 @@ extern "C" EMSCRIPTEN_KEEPALIVE void proxy_onConfigure(char* configuration, int
 }
 
 extern "C" EMSCRIPTEN_KEEPALIVE void proxy_onStart() {
+  logTrace(std::string("test trace") + " logging");
   logDebug(std::string("test debug") + " logging");
-  logInfo(std::string("test info") + " logging");
+  logError(std::string("test error") + " logging");
 }
 
 extern "C" EMSCRIPTEN_KEEPALIVE void proxy_onTick() {
-  logError(std::string("test tick") + " logging");
+  logInfo(std::string("test tick") + " logging");
 }