Add a test for preview2-specific reads/writes (#8271)

Inspired by #8257 to show that the code being deleted in #8268 is needed
for this test to pass.

crates/test-programs/src/bin/preview2_file_read_write.rs

@@ -0,0 +1,28 @@
+use test_programs::wasi;
+use test_programs::wasi::filesystem::types::{DescriptorFlags, OpenFlags, PathFlags};
+
+fn main() {
+    let preopens = wasi::filesystem::preopens::get_directories();
+    let (dir, _) = &preopens[0];
+
+    let filename = "test.txt";
+    let file = dir
+        .open_at(
+            PathFlags::empty(),
+            filename,
+            OpenFlags::CREATE,
+            DescriptorFlags::READ | DescriptorFlags::WRITE,
+        )
+        .unwrap();
+    let stream = file.write_via_stream(5).unwrap();
+    stream.blocking_write_and_flush(b"Hello, ").unwrap();
+    stream.blocking_write_and_flush(b"World!").unwrap();
+    drop(stream);
+
+    let stream = file.read_via_stream(0).unwrap();
+    let contents = stream.blocking_read(100).unwrap();
+    assert_eq!(contents, b"\0\0\0\0\0Hello, World!");
+    drop((stream, file));
+
+    dir.unlink_file_at(filename).unwrap();
+}

crates/wasi/tests/all/async_.rs

@@ -13,7 +13,11 @@ async fn run(path: &str, inherit_stdio: bool) -> Result<()> {
     let mut linker = Linker::new(&engine);
     add_to_linker_async(&mut linker)?;
 
-    let (mut store, _td) = store(&engine, name, inherit_stdio)?;
+    let (mut store, _td) = store(&engine, name, |builder| {
+        if inherit_stdio {
+            builder.inherit_stdio();
+        }
+    })?;
     let component = Component::from_file(&engine, path)?;
     let (command, _instance) = Command::instantiate_async(&mut store, &component, &linker).await?;
     command
@@ -379,3 +383,9 @@ async fn preview2_pollable_traps() {
 async fn preview2_adapter_badfd() {
     run(PREVIEW2_ADAPTER_BADFD_COMPONENT, false).await.unwrap()
 }
+#[test_log::test(tokio::test(flavor = "multi_thread"))]
+async fn preview2_file_read_write() {
+    run(PREVIEW2_FILE_READ_WRITE_COMPONENT, false)
+        .await
+        .unwrap()
+}

crates/wasi/tests/all/main.rs

@@ -30,18 +30,18 @@ fn prepare_workspace(exe_name: &str) -> Result<TempDir> {
     Ok(tempdir)
 }
 
-fn store(engine: &Engine, name: &str, inherit_stdio: bool) -> Result<(Store<Ctx>, TempDir)> {
+fn store(
+    engine: &Engine,
+    name: &str,
+    configure: impl FnOnce(&mut WasiCtxBuilder),
+) -> Result<(Store<Ctx>, TempDir)> {
     let stdout = MemoryOutputPipe::new(4096);
     let stderr = MemoryOutputPipe::new(4096);
     let workspace = prepare_workspace(name)?;
 
     // Create our wasi context.
     let mut builder = WasiCtxBuilder::new();
-    if inherit_stdio {
-        builder.inherit_stdio();
-    } else {
-        builder.stdout(stdout.clone()).stderr(stderr.clone());
-    }
+    builder.stdout(stdout.clone()).stderr(stderr.clone());
 
     builder
         .args(&[name, "."])
@@ -53,6 +53,7 @@ fn store(engine: &Engine, name: &str, inherit_stdio: bool) -> Result<(Store<Ctx>
         builder.env(var, val);
     }
 
+    configure(&mut builder);
     let ctx = Ctx {
         wasi: builder.build_p1(),
         stderr,

crates/wasi/tests/all/preview1.rs

@@ -14,7 +14,11 @@ async fn run(path: &str, inherit_stdio: bool) -> Result<()> {
     add_to_linker_async(&mut linker, |t| &mut t.wasi)?;
 
     let module = Module::from_file(&engine, path)?;
-    let (mut store, _td) = store(&engine, name, inherit_stdio)?;
+    let (mut store, _td) = store(&engine, name, |builder| {
+        if inherit_stdio {
+            builder.inherit_stdio();
+        }
+    })?;
     let instance = linker.instantiate_async(&mut store, &module).await?;
     let start = instance.get_typed_func::<(), ()>(&mut store, "_start")?;
     start.call_async(&mut store, ()).await?;

crates/wasi/tests/all/sync.rs

@@ -13,13 +13,22 @@ fn run(path: &str, inherit_stdio: bool) -> Result<()> {
     let mut linker = Linker::new(&engine);
     add_to_linker_sync(&mut linker)?;
 
-    let (mut store, _td) = store(&engine, name, inherit_stdio)?;
     let component = Component::from_file(&engine, path)?;
-    let (command, _instance) = Command::instantiate(&mut store, &component, &linker)?;
-    command
-        .wasi_cli_run()
-        .call_run(&mut store)?
-        .map_err(|()| anyhow::anyhow!("run returned a failure"))
+
+    for blocking in [false, true] {
+        let (mut store, _td) = store(&engine, name, |builder| {
+            if inherit_stdio {
+                builder.inherit_stdio();
+            }
+            builder.allow_blocking_current_thread(blocking);
+        })?;
+        let (command, _instance) = Command::instantiate(&mut store, &component, &linker)?;
+        command
+            .wasi_cli_run()
+            .call_run(&mut store)?
+            .map_err(|()| anyhow::anyhow!("run returned a failure"))?;
+    }
+    Ok(())
 }
 
 foreach_preview1!(assert_test_exists);
@@ -314,3 +323,7 @@ fn preview2_pollable_traps() {
 fn preview2_adapter_badfd() {
     run(PREVIEW2_ADAPTER_BADFD_COMPONENT, false).unwrap()
 }
+#[test_log::test]
+fn preview2_file_read_write() {
+    run(PREVIEW2_FILE_READ_WRITE_COMPONENT, false).unwrap()
+}