Merge pull request #135 from wingo/filesystem-io

wasi:filesystem@0.3.0-rc-2025-09-16: Add tests for read/write/append

Author: wingo

tests/rust/wasm32-wasip3/Cargo.lock

@@ -5,3 +5,4 @@ edition = "2024"
 
 [dependencies]
 wit-bindgen = "0.48"
+futures = "0.3.31"

tests/rust/wasm32-wasip3/Cargo.toml

@@ -0,0 +1,3 @@
+{
+    "dirs": ["fs-tests.dir"]
+}

tests/rust/wasm32-wasip3/src/bin/filesystem-io.json

@@ -0,0 +1,226 @@
+use futures::join;
+use std::process;
+extern crate wit_bindgen;
+
+wit_bindgen::generate!({
+    inline: r"
+  package test:test;
+
+  world test {
+      include wasi:filesystem/imports@0.3.0-rc-2025-09-16;
+      include wasi:cli/command@0.3.0-rc-2025-09-16;
+  }
+",
+    additional_derives: [PartialEq, Eq, Hash, Clone],
+    // Work around https://github.com/bytecodealliance/wasm-tools/issues/2285.
+    features:["clocks-timezone"],
+    generate_all
+});
+
+use wasi::filesystem::types::Descriptor;
+use wasi::filesystem::types::{DescriptorFlags, ErrorCode, OpenFlags, PathFlags};
+use wit_bindgen::StreamResult;
+
+async fn pread(fd: &Descriptor, size: usize, offset: u64) -> Result<Vec<u8>, ErrorCode> {
+    let (mut rx, future) = fd.read_via_stream(offset);
+    let data = Vec::<u8>::with_capacity(size);
+    let mut bytes_read = 0;
+    let (mut result, mut data) = rx.read(data).await;
+    loop {
+        match result {
+            StreamResult::Complete(n) => {
+                assert!(n <= size - bytes_read);
+                bytes_read += n;
+                assert_eq!(data.len(), bytes_read);
+                if bytes_read == size {
+                    break;
+                }
+                (result, data) = rx.read(data).await;
+            }
+            StreamResult::Dropped => {
+                // https://github.com/bytecodealliance/wit-bindgen/issues/1396
+                assert!(data.len() >= bytes_read);
+                break;
+            }
+            StreamResult::Cancelled => {
+                panic!("who cancelled the stream?");
+            }
+        }
+    }
+    drop(rx);
+    match future.await {
+        Ok(()) => Ok(data),
+        Err(err) => Err(err),
+    }
+}
+
+async fn pwrite(fd: &Descriptor, offset: u64, data: &[u8]) -> Result<usize, ErrorCode> {
+    let (mut tx, rx) = wit_stream::new();
+    let future = fd.write_via_stream(rx, offset);
+    let len = data.len();
+    let mut written: usize = 0;
+    let mut result: Result<(), ErrorCode> = Ok(());
+    join! {
+        async {
+            let (mut result, mut buf) = tx.write(data.to_vec()).await;
+            loop {
+                match result {
+                    StreamResult::Complete(n) => {
+                        assert!(n <= len - written);
+                        written += n;
+                        assert_eq!(buf.remaining(), len - written);
+                        if buf.remaining() != 0 {
+                            (result, buf) = tx.write_buf(buf).await;
+                        } else {
+                            break;
+                        }
+                    }
+                    StreamResult::Dropped => {
+                        // https://github.com/bytecodealliance/wit-bindgen/issues/1396
+                        assert!(buf.remaining() <= len - written);
+                        panic!("receiver dropped the stream?");
+                    }
+                    StreamResult::Cancelled => {
+                        break;
+                    }
+                }
+            }
+            assert_eq!(buf.remaining(), len - written);
+            drop(tx);
+        },
+        async { result = future.await; }
+    };
+    match result {
+        Ok(()) => Ok(written),
+        Err(err) => Err(err),
+    }
+}
+
+async fn pappend(fd: &Descriptor, data: &[u8]) -> Result<usize, ErrorCode> {
+    let (mut tx, rx) = wit_stream::new();
+    let future = fd.append_via_stream(rx);
+    let initial_size = fd.stat().await.unwrap().size as usize;
+    let len = data.len();
+    let mut written: usize = 0;
+    let mut result: Result<(), ErrorCode> = Ok(());
+    join! {
+        async {
+            let (mut result, mut buf) = tx.write(data.to_vec()).await;
+            loop {
+                match result {
+                    StreamResult::Complete(n) => {
+                        assert!(n <= len - written);
+                        written += n;
+                        assert_eq!(buf.remaining(), len - written);
+                        assert_eq!(fd.stat().await.unwrap().size as usize,
+                                   initial_size + written);
+                        if buf.remaining() != 0 {
+                            (result, buf) = tx.write_buf(buf).await;
+                        } else {
+                            break;
+                        }
+                    }
+                    StreamResult::Dropped => {
+                        panic!("receiver dropped the stream?");
+                    }
+                    StreamResult::Cancelled => {
+                        break;
+                    }
+                }
+            }
+            assert_eq!(buf.remaining(), len - written);
+            drop(tx);
+        },
+        async { result = future.await; }
+    };
+    match result {
+        Ok(()) => Ok(written),
+        Err(err) => Err(err),
+    }
+}
+
+async fn read_to_eof(fd: &Descriptor, offset: u64) -> Vec<u8> {
+    let (stream, success) = fd.read_via_stream(offset);
+    let ret = stream.collect().await;
+    success.await.unwrap();
+    ret
+}
+
+async fn test_io(dir: &Descriptor) {
+    let open = |path: &str, oflags: OpenFlags, fdflags: DescriptorFlags| -> _ {
+        dir.open_at(PathFlags::empty(), path.to_string(), oflags, fdflags)
+    };
+    let open_r = |path: &str| -> _ { open(path, OpenFlags::empty(), DescriptorFlags::READ) };
+    let creat = |path: &str| -> _ {
+        open(
+            path,
+            OpenFlags::CREATE | OpenFlags::EXCLUSIVE,
+            DescriptorFlags::READ | DescriptorFlags::WRITE,
+        )
+    };
+    let rm = |path: &str| dir.unlink_file_at(path.to_string());
+
+    let a = open_r("a.txt").await.unwrap();
+
+    pread(&a, 0, 0).await.unwrap();
+    pread(&a, 0, 1).await.unwrap();
+    pread(&a, 0, 6).await.unwrap();
+    pread(&a, 0, 7).await.unwrap();
+    pread(&a, 0, 17).await.unwrap();
+
+    assert_eq!(&pread(&a, 1, 0).await.unwrap(), b"t");
+    assert_eq!(&pread(&a, 1, 1).await.unwrap(), b"e");
+    assert_eq!(&pread(&a, 1, 6).await.unwrap(), b"\n");
+    assert_eq!(&pread(&a, 1, 7).await.unwrap(), b"");
+    assert_eq!(&pread(&a, 1, 17).await.unwrap(), b"");
+
+    assert_eq!(&read_to_eof(&a, 0).await, b"test-a\n");
+    assert_eq!(&read_to_eof(&a, 1).await, b"est-a\n");
+    assert_eq!(&read_to_eof(&a, 6).await, b"\n");
+    assert_eq!(&read_to_eof(&a, 7).await, b"");
+    assert_eq!(&read_to_eof(&a, 17).await, b"");
+
+    // No-op on read-only fds.
+    a.sync_data().await.unwrap();
+    a.sync().await.unwrap();
+
+    assert_eq!(pread(&a, 1, u64::MAX).await, Err(ErrorCode::Invalid));
+
+    let c = creat("c.cleanup").await.unwrap();
+    assert_eq!(&read_to_eof(&c, 0).await, b"");
+    assert_eq!(pwrite(&c, 0, b"hello!").await, Ok(b"hello!".len()));
+    assert_eq!(&read_to_eof(&c, 0).await, b"hello!");
+    assert_eq!(pwrite(&c, 0, b"byeee").await, Ok(b"byeee".len()));
+    assert_eq!(&read_to_eof(&c, 0).await, b"byeee!");
+    assert_eq!(pappend(&c, b" laters!!").await, Ok(b" laters!!".len()));
+    assert_eq!(&read_to_eof(&c, 0).await, b"byeee! laters!!");
+    c.sync_data().await.unwrap();
+    assert_eq!(
+        &read_to_eof(&open_r("c.cleanup").await.unwrap(), 0).await,
+        b"byeee! laters!!"
+    );
+    c.sync().await.unwrap();
+
+    rm("c.cleanup").await.unwrap();
+}
+
+struct Component;
+export!(Component);
+impl exports::wasi::cli::run::Guest for Component {
+    async fn run() -> Result<(), ()> {
+        match &wasi::filesystem::preopens::get_directories()[..] {
+            [(dir, dirname)] if dirname == "fs-tests.dir" => {
+                test_io(dir).await;
+            }
+            [..] => {
+                eprintln!("usage: run with one open dir named 'fs-tests.dir'");
+                process::exit(1)
+            }
+        };
+        Ok(())
+    }
+}
+
+fn main() {
+    unreachable!("main is a stub");
+}