Add wasmldr integration test(s)

Hooray! We can actually run wasm now!

 Here's what this patch does:

* Remove internal/wasmldr's build.rs
* Move wasmldr test sources to tests/wasm/*.wat
* Build tests/wasm/*.wat to OUT_DIR/bin/*.wasm in build.rs
* Add tests/wasmldr_tests.rs, which runs the .wasm test binaries

The tricky bit was getting Rust to pass open file descriptors to the
child process, since it *really* wants to set FD_CLOEXEC on everything.
This isn't pretty, but it's a start.

Signed-off-by: Will Woods <will@profian.com>

Cargo.toml

@@ -55,6 +55,7 @@ vdso = "0.1"
 
 [build-dependencies]
 cc = "1.0"
+wat = "1.0"
 walkdir = "2"
 protobuf-codegen-pure = "2.25"
 sallyport = { git = "https://github.com/enarx/sallyport", rev = "a567a22665c7e5ba88a8c4acd64ab43ee32b4681", features = [ "asm" ] }

build.rs

@@ -107,6 +107,17 @@ fn build_cc_tests(in_path: &Path, out_path: &Path) {
     }
 }
 
+fn build_wasm_tests(in_path: &Path, out_path: &Path) {
+    for wat in find_files_with_extensions(&["wat"], &in_path) {
+        let wasm = out_path
+            .join(wat.file_stem().unwrap())
+            .with_extension("wasm");
+        let bin = wat::parse_file(&wat).unwrap_or_else(|_| panic!("failed to compile {:?}", &wat));
+        std::fs::write(&wasm, &bin).unwrap_or_else(|_| panic!("failed to write {:?}", &wasm));
+        println!("cargo:rerun-if-changed={}", &wat.display());
+    }
+}
+
 // Build a binary named `bin_name` from the crate located at `in_dir`,
 // targeting `target_name`, then strip the resulting binary and place it
 // at `out_dir`/bin/`bin_name`.
@@ -235,6 +246,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     build_cc_tests(&Path::new(CRATE).join(TEST_BINS_IN), &out_dir_bin);
     build_rs_tests(&Path::new(CRATE).join(TEST_BINS_IN), &out_dir_bin);
+    build_wasm_tests(&Path::new(CRATE).join("tests/wasm"), &out_dir_bin);
 
     let target = "x86_64-unknown-linux-musl";
 

tests/wasmldr_tests.rs

@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: Apache-2.0
+
+use process_control::{ChildExt, Output, Timeout};
+use std::fs::File;
+use std::os::unix::io::{IntoRawFd, RawFd};
+use std::os::unix::process::CommandExt;
+use std::path::Path;
+use std::process::{Command, Stdio};
+
+extern crate libc;
+use libc::c_int;
+
+use std::io;
+use std::io::Write;
+use std::time::Duration;
+
+mod common;
+use common::{check_output, CRATE, KEEP_BIN, OUT_DIR, TEST_BINS_OUT, TIMEOUT_SECS};
+
+use serial_test::serial;
+
+const MODULE_FD: RawFd = 3;
+
+// wrap a libc call to return io::Result<c_int>
+fn cvt(rv: c_int) -> io::Result<c_int> {
+    if rv == -1 {
+        Err(io::Error::last_os_error())
+    } else {
+        Ok(rv)
+    }
+}
+
+// wrap a libc call to return io::Result<()>
+fn cv(rv: c_int) -> io::Result<()> {
+    cvt(rv).and(Ok(()))
+}
+
+trait CommandFdExt {
+    fn inherit_with_fd(&mut self, file: impl IntoRawFd, child_fd: RawFd) -> &mut Self;
+}
+
+impl CommandFdExt for Command {
+    fn inherit_with_fd(&mut self, file: impl IntoRawFd, child_fd: RawFd) -> &mut Self {
+        let fd = file.into_raw_fd();
+        if fd == child_fd {
+            unsafe {
+                self.pre_exec(move || cv(libc::fcntl(fd, libc::F_SETFD, 0)));
+            }
+        } else {
+            unsafe {
+                self.pre_exec(move || cv(libc::dup2(fd, child_fd)));
+            }
+        }
+        self
+    }
+}
+
+pub fn wasmldr_exec<'a>(wasm: &str, input: impl Into<Option<&'a [u8]>>) -> Output {
+    let wasm_path = Path::new(CRATE)
+        .join(OUT_DIR)
+        .join(TEST_BINS_OUT)
+        .join(wasm);
+    let wasm_file =
+        File::open(wasm_path).unwrap_or_else(|e| panic!("failed to open `{}`: {:#?}", wasm, e));
+
+    let mut child = Command::new(&String::from(KEEP_BIN))
+        .current_dir(CRATE)
+        .arg("exec")
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .inherit_with_fd(wasm_file, MODULE_FD)
+        .spawn()
+        .unwrap_or_else(|e| panic!("failed to run `{}`: {:#?}", wasm, e));
+
+    if let Some(input) = input.into() {
+        child
+            .stdin
+            .as_mut()
+            .unwrap()
+            .write_all(input)
+            .expect("failed to write stdin to child");
+
+        drop(child.stdin.take());
+    }
+
+    let output = child
+        .with_output_timeout(Duration::from_secs(TIMEOUT_SECS))
+        .terminating()
+        .wait()
+        .unwrap_or_else(|e| panic!("failed to run `{}`: {:#?}", wasm, e))
+        .unwrap_or_else(|| panic!("process `{}` timed out", wasm));
+
+    assert!(
+        output.status.code().is_some(),
+        "process `{}` terminated by signal {:?}",
+        wasm,
+        output.status.signal()
+    );
+
+    output
+}
+
+fn run_wasm_test<'a>(
+    wasm: &str,
+    status: i32,
+    input: impl Into<Option<&'a [u8]>>,
+    expected_stdout: impl Into<Option<&'a [u8]>>,
+    expected_stderr: impl Into<Option<&'a [u8]>>,
+) -> Output {
+    let output = wasmldr_exec(wasm, input);
+    check_output(&output, status, expected_stdout, expected_stderr);
+    output
+}
+
+#[test]
+#[serial]
+fn return_1() {
+    // This module does, in fact, return 1. But function return values
+    // are separate from setting the process exit status code, so
+    // we still expect a return code of '0' here.
+    run_wasm_test("return_1.wasm", 0, None, None, None);
+}
+
+#[test]
+#[serial]
+fn wasi_snapshot1() {
+    // This module uses WASI to return the number of commandline args.
+    // Since we don't currently do anything with the function return value,
+    // we don't get any output here, and we expect '0', as above.
+    run_wasm_test("wasi_snapshot1.wasm", 0, None, None, None);
+}
+
+#[test]
+#[serial]
+fn hello_wasi_snapshot1() {
+    // This module just prints "Hello, world!" to stdout. Hooray!
+    run_wasm_test(
+        "hello_wasi_snapshot1.wasm",
+        0,
+        None,
+        &b"Hello, world!\n"[..],
+        None,
+    );
+}
+
+#[test]
+#[serial]
+fn no_export() {
+    // This module has no exported functions, so we get Error::ExportNotFound,
+    // which wasmldr maps to EX_DATAERR (65) at process exit.
+    run_wasm_test("no_export.wasm", 65, None, None, None);
+}