fix crash on Windows; add version embedding (#17)

This fixes an issue causing `wizer` to fail due to `CPython` calling
`fd_filestat_get` on stdio descriptors, which causes Wasmtime's WASI
implementation to trap if those descriptors don't point to actual
files.

This also updates the `spin-sdk` dependency to allow version embedding
per
https://github.com/fermyon/spin/blob/main/docs/content/sips/011-component-versioning.md.

Signed-off-by: Joel Dice <joel.dice@fermyon.com>

Author: dicej

crates/spin-python-cli/src/main.rs

@@ -5,7 +5,7 @@ use {
     clap::Parser,
     std::{
         env, fs,
-        io::Cursor,
+        io::{self, Cursor, Seek},
         path::{Path, PathBuf},
         process::Command,
         str,
@@ -105,6 +105,17 @@ fn main() -> Result<()> {
             )
         }
 
+        // Spawn a subcommand to do the real work.  This gives us an opportunity to clear the environment so that
+        // build-time environment variables don't end up in the Wasm module we're building.
+        //
+        // Note that we need to use temporary files for stdio instead of the default inheriting behavior since (as
+        // of this writing) CPython interacts poorly with Wasmtime's WASI implementation if any of the stdio
+        // descriptors point to non-files on Windows.  Specifically, the WASI implementation will trap when CPython
+        // calls `fd_filestat_get` on non-files.
+
+        let mut stdout = tempfile::tempfile()?;
+        let mut stderr = tempfile::tempfile()?;
+
         let status = Command::new(env::args().next().unwrap())
             .env_clear()
             .env("SPIN_PYTHON_WIZEN", "1")
@@ -116,9 +127,18 @@ fn main() -> Result<()> {
             )
             .arg(&python_path)
             .arg(&options.output)
+            .stdin(tempfile::tempfile()?)
+            .stdout(stdout.try_clone()?)
+            .stderr(stderr.try_clone()?)
             .status()?;
 
         if !status.success() {
+            stdout.rewind()?;
+            io::copy(&mut stdout, &mut io::stdout().lock())?;
+
+            stderr.rewind()?;
+            io::copy(&mut stderr, &mut io::stderr().lock())?;
+
             bail!("Couldn't create wasm from input");
         }
 

crates/spin-python-engine/Cargo.toml

@@ -11,7 +11,7 @@ crate-type = [ "cdylib" ]
 anyhow = "1"
 bytes = { version = "1.2.1", features = ["serde"] }
 http = "0.2"
-spin-sdk = { git = "https://github.com/fermyon/spin" }
+spin-sdk = { git = "https://github.com/fermyon/spin", default-features = false }
 wit-bindgen-rust = { git = "https://github.com/bytecodealliance/wit-bindgen", rev = "dde4694aaa6acf9370206527a798ac4ba6a8c5b8" }
 pyo3 = { version = "0.17.3", features = [ "abi3-py310" ] }
 once_cell = "1.16.0"

crates/spin-python-engine/src/lib.rs

@@ -24,6 +24,9 @@ thread_local! {
     static ENVIRON: OnceCell<Py<PyMapping>> = OnceCell::new();
 }
 
+#[export_name = "spin-sdk-language-python"]
+extern "C" fn __spin_sdk_language() {}
+
 fn bytes(py: Python<'_>, src: &[u8]) -> PyResult<Py<PyBytes>> {
     Ok(PyBytes::new_with(py, src.len(), |dst| {
         dst.copy_from_slice(src);