Merge #726

726: Add serialization for WASI state  r=MarkMcCaskey a=MarkMcCaskey

part of #700 

Due to the trait objects from #583 , we can't use `serde` derive for this or use serde traits directly, we have to do some custom serialization (edit: luckily there's a crate for this: `typetag`)

Co-authored-by: Mark McCaskey <mark@wasmer.io>
Co-authored-by: Mark McCaskey <markmccaskey@users.noreply.github.com>
Co-authored-by: Syrus Akbary <me@syrusakbary.com>

Cargo.toml

@@ -66,6 +66,10 @@ wabt = "0.9.1"
 glob = "0.3.0"
 rustc_version = "0.2.3"
 
+[dev-dependencies]
+serde = { version = "1", features = ["derive"] } # used by the plugin example
+typetag = "0.1" # used by the plugin example
+
 [features]
 default = ["fast-tests", "wasi", "backend-cranelift"]
 "loader-kernel" = ["wasmer-kernel-loader"]

Makefile

@@ -70,12 +70,13 @@ wasitests-singlepass: wasitests-setup
 	cargo test --manifest-path lib/wasi-tests/Cargo.toml --release --features singlepass -- --test-threads=1
 
 wasitests-cranelift: wasitests-setup
-	cargo test --manifest-path lib/wasi-tests/Cargo.toml --release --features clif -- --test-threads=1
+	cargo test --manifest-path lib/wasi-tests/Cargo.toml --release --features clif -- --test-threads=1 --nocapture
 
 wasitests-llvm: wasitests-setup
 	cargo test --manifest-path lib/wasi-tests/Cargo.toml --release --features llvm -- --test-threads=1
 
-wasitests-unit:
+wasitests-unit: wasitests-setup
+	cargo test --manifest-path lib/wasi-tests/Cargo.toml --release --features clif -- --test-threads=1 --nocapture
 	cargo test --manifest-path lib/wasi/Cargo.toml --release
 
 wasitests: wasitests-unit wasitests-singlepass wasitests-cranelift wasitests-llvm

examples/plugin.rs

@@ -1,3 +1,4 @@
+use serde::{Deserialize, Serialize};
 use wasmer_runtime::{func, imports, instantiate};
 use wasmer_runtime_core::vm::Ctx;
 use wasmer_wasi::{
@@ -13,7 +14,7 @@ fn it_works(_ctx: &mut Ctx) -> i32 {
     5
 }
 
-#[derive(Debug)]
+#[derive(Debug, Serialize, Deserialize)]
 pub struct LoggingWrapper {
     pub wasm_module_name: String,
 }
@@ -86,6 +87,8 @@ impl std::io::Write for LoggingWrapper {
 }
 
 // the WasiFile methods aren't relevant for a write-only Stdout-like implementation
+// we must use typetag and serde so that our trait objects can be safely Serialized and Deserialized
+#[typetag::serde]
 impl WasiFile for LoggingWrapper {
     fn last_accessed(&self) -> u64 {
         0

lib/wasi-tests/Cargo.toml

@@ -10,6 +10,7 @@ build = "build/mod.rs"
 
 [dependencies]
 wasmer-runtime-core = { path = "../runtime-core", version = "0.6.0" }
+wasmer-runtime = { path = "../runtime", version = "0.6.0" }
 wasmer-wasi = { path = "../wasi", version = "0.6.0" }
 # hack to get tests to work
 wasmer-singlepass-backend = { path = "../singlepass-backend", version = "0.6.0", optional = true }

lib/wasi-tests/src/lib.rs

@@ -1 +1,60 @@
-// nothing to see here
+#![cfg(test)]
+use wasmer_runtime::{compile, Func};
+use wasmer_runtime_core::vm::Ctx;
+use wasmer_wasi::{state::*, *};
+
+use std::ffi::c_void;
+
+#[test]
+fn serializing_works() {
+    let args = vec![
+        b"program_name".into_iter().cloned().collect(),
+        b"arg1".into_iter().cloned().collect(),
+    ];
+    let envs = vec![
+        b"PATH=/bin".into_iter().cloned().collect(),
+        b"GOROOT=$HOME/.cargo/bin".into_iter().cloned().collect(),
+    ];
+    let wasm_binary = include_bytes!("../wasitests/fd_read.wasm");
+    let import_object = generate_import_object(
+        args.clone(),
+        envs.clone(),
+        vec![],
+        vec![(
+            ".".to_string(),
+            std::path::PathBuf::from("wasitests/test_fs/hamlet"),
+        )],
+    );
+    let module = compile(&wasm_binary[..])
+        .map_err(|e| format!("Can't compile module: {:?}", e))
+        .unwrap();
+
+    let state_bytes = {
+        let instance = module.instantiate(&import_object).unwrap();
+
+        let start: Func<(), ()> = instance.func("_start").unwrap();
+        start.call().unwrap();
+        let state = get_wasi_state(instance.context());
+
+        assert_eq!(state.args, args);
+        assert_eq!(state.envs, envs);
+        let bytes = state.freeze().unwrap();
+
+        bytes
+    };
+
+    let mut instance = module.instantiate(&import_object).unwrap();
+
+    let wasi_state = Box::new(WasiState::unfreeze(&state_bytes).unwrap());
+
+    instance.context_mut().data = Box::into_raw(wasi_state) as *mut c_void;
+
+    let second_entry: Func<(), i32> = instance.func("second_entry").unwrap();
+    let result = second_entry.call().unwrap();
+    assert_eq!(result, true as i32);
+}
+
+#[allow(clippy::mut_from_ref)]
+pub(crate) fn get_wasi_state(ctx: &Ctx) -> &mut WasiState {
+    unsafe { state::get_wasi_state(&mut *(ctx as *const Ctx as *mut Ctx)) }
+}

lib/wasi-tests/tests/wasitests/fd_read.rs

@@ -0,0 +1,14 @@
+#[test]
+fn test_fd_read() {
+    assert_wasi_output!(
+        "../../wasitests/fd_read.wasm",
+        "fd_read",
+        vec![],
+        vec![(
+            ".".to_string(),
+            ::std::path::PathBuf::from("wasitests/test_fs/hamlet")
+        ),],
+        vec![],
+        "../../wasitests/fd_read.out"
+    );
+}

lib/wasi-tests/tests/wasitests/mod.rs

@@ -9,6 +9,7 @@ mod create_dir;
 mod envvar;
 mod fd_allocate;
 mod fd_pread;
+mod fd_read;
 mod fd_sync;
 mod file_metadata;
 mod fs_sandbox_test;

lib/wasi-tests/wasitests/fd_read.out

@@ -0,0 +1,3 @@
+SCENE IV. The Queen's closet.
+
+    Enter QUEEN GERTRUDE and POLO