7e0d9decbf
* Add support for virtual files (eg, not backed by an OS file). Virtual files are implemented through trait objects, with a default implementation that tries to behave like on-disk files, but entirely backed by in-memory structures. Co-authored-by: Dan Gohman <sunfish@mozilla.com>
98 lines
3.1 KiB
Rust
98 lines
3.1 KiB
Rust
use anyhow::{bail, Context};
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use std::fs::File;
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use std::path::Path;
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use wasi_common::VirtualDirEntry;
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use wasmtime::{Instance, Module, Store};
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#[derive(Clone, Copy, Debug)]
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pub enum PreopenType {
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/// Preopens should be satisfied with real OS files.
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OS,
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/// Preopens should be satisfied with virtual files.
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Virtual,
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}
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pub fn instantiate(
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data: &[u8],
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bin_name: &str,
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workspace: Option<&Path>,
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preopen_type: PreopenType,
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) -> anyhow::Result<()> {
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let store = Store::default();
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// Create our wasi context with pretty standard arguments/inheritance/etc.
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// Additionally register any preopened directories if we have them.
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let mut builder = wasi_common::WasiCtxBuilder::new();
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builder.arg(bin_name).arg(".").inherit_stdio();
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if let Some(workspace) = workspace {
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match preopen_type {
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PreopenType::OS => {
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let preopen_dir = wasi_common::preopen_dir(workspace)
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.context(format!("error while preopening {:?}", workspace))?;
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builder.preopened_dir(preopen_dir, ".");
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}
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PreopenType::Virtual => {
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// we can ignore the workspace path for virtual preopens because virtual preopens
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// don't exist in the filesystem anyway - no name conflict concerns.
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builder.preopened_virt(VirtualDirEntry::empty_directory(), ".");
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}
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}
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}
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// The nonstandard thing we do with `WasiCtxBuilder` is to ensure that
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// `stdin` is always an unreadable pipe. This is expected in the test suite
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// where `stdin` is never ready to be read. In some CI systems, however,
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// stdin is closed which causes tests to fail.
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let (reader, _writer) = os_pipe::pipe()?;
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builder.stdin(reader_to_file(reader));
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let snapshot1 = wasmtime_wasi::Wasi::new(&store, builder.build()?);
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let module = Module::new(&store, &data).context("failed to create wasm module")?;
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let imports = module
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.imports()
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.iter()
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.map(|i| {
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let field_name = i.name();
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if let Some(export) = snapshot1.get_export(field_name) {
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Ok(export.clone().into())
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} else {
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bail!(
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"import {} was not found in module {}",
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field_name,
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i.module(),
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)
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}
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})
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.collect::<Result<Vec<_>, _>>()?;
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let instance = Instance::new(&module, &imports).context(format!(
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"error while instantiating Wasm module '{}'",
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bin_name,
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))?;
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let export = instance
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.get_export("_start")
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.context("expected a _start export")?
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.clone();
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export
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.func()
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.context("expected export to be a func")?
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.call(&[])?;
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Ok(())
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}
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#[cfg(unix)]
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fn reader_to_file(reader: os_pipe::PipeReader) -> File {
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use std::os::unix::prelude::*;
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unsafe { File::from_raw_fd(reader.into_raw_fd()) }
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}
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#[cfg(windows)]
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fn reader_to_file(reader: os_pipe::PipeReader) -> File {
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use std::os::windows::prelude::*;
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unsafe { File::from_raw_handle(reader.into_raw_handle()) }
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}
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