Merge pull request #2776 from bytecodealliance/pch/wasmtime_wasi_usability

`wasmtime-wasi` usability: re-exports of common siblings

crates/c-api/src/wasi.rs

@@ -1,7 +1,6 @@
 //! The WASI embedding API definitions for Wasmtime.
 use crate::{wasm_extern_t, wasm_importtype_t, wasm_store_t, wasm_trap_t};
 use anyhow::Result;
-use cap_std::fs::Dir;
 use std::cell::RefCell;
 use std::collections::HashMap;
 use std::ffi::CStr;
@@ -11,11 +10,12 @@ use std::path::{Path, PathBuf};
 use std::rc::Rc;
 use std::slice;
 use std::str;
-use wasi_cap_std_sync::WasiCtxBuilder;
-use wasi_common::WasiCtx;
 use wasmtime::{Extern, Linker, Trap};
 use wasmtime_wasi::{
-    snapshots::preview_0::Wasi as WasiSnapshot0, snapshots::preview_1::Wasi as WasiPreview1,
+    snapshots::preview_0::Wasi as WasiSnapshot0,
+    snapshots::preview_1::Wasi as WasiPreview1,
+    sync::{Dir, WasiCtxBuilder},
+    WasiCtx,
 };
 
 unsafe fn cstr_to_path<'a>(path: *const c_char) -> Option<&'a Path> {
@@ -186,7 +186,7 @@ pub unsafe extern "C" fn wasi_config_preopen_dir(
     };
 
     let dir = match cstr_to_path(path) {
-        Some(p) => match cap_std::fs::Dir::open_ambient_dir(p) {
+        Some(p) => match Dir::open_ambient_dir(p) {
             Ok(d) => d,
             Err(_) => return false,
         },

crates/wasi-common/cap-std-sync/src/lib.rs

@@ -14,6 +14,10 @@
 //! `cap_std::fs::Dir`, and provides convenience methods for inheriting the
 //! parent process's stdio, args, and env.
 //!
+//! For the convenience of consumers, `cap_std::fs::Dir` is re-exported from
+//! this crate. This saves consumers tracking an additional dep on the exact
+//! version of cap_std used by this crate, if they want to avoid it.
+//!
 //! The only place we expect to run into long-term compatibility issues
 //! between `wasi-cap-std-sync` and the other impl crates that will come later
 //! is in the `Sched` abstraction. Once we can build an async scheduler based
@@ -33,6 +37,7 @@ pub mod file;
 pub mod sched;
 pub mod stdio;
 
+pub use cap_std::fs::Dir;
 pub use clocks::clocks_ctx;
 pub use sched::sched_ctx;
 
@@ -110,13 +115,9 @@ impl WasiCtxBuilder {
     pub fn inherit_stdio(self) -> Self {
         self.inherit_stdin().inherit_stdout().inherit_stderr()
     }
-    pub fn preopened_dir(
-        self,
-        dir: cap_std::fs::Dir,
-        path: impl AsRef<Path>,
-    ) -> Result<Self, Error> {
+    pub fn preopened_dir(self, dir: Dir, guest_path: impl AsRef<Path>) -> Result<Self, Error> {
         let dir = Box::new(crate::dir::Dir::from_cap_std(dir));
-        Ok(WasiCtxBuilder(self.0.preopened_dir(dir, path)?))
+        Ok(WasiCtxBuilder(self.0.preopened_dir(dir, guest_path)?))
     }
     pub fn build(self) -> Result<WasiCtx, Error> {
         self.0.build()

crates/wasi/Cargo.toml

@@ -14,7 +14,12 @@ build = "build.rs"
 
 [dependencies]
 wasi-common = { path = "../wasi-common", version = "0.25.0" }
+wasi-cap-std-sync = { path = "../wasi-common/cap-std-sync", version = "0.25.0", optional = true }
 wiggle = { path = "../wiggle", default-features = false, version = "0.25.0" }
 wasmtime-wiggle = { path = "../wiggle/wasmtime", default-features = false, version = "0.25.0" }
 wasmtime = { path = "../wasmtime", default-features = false, version = "0.25.0" }
 anyhow = "1.0"
+
+[features]
+default = ["sync"]
+sync = ["wasi-cap-std-sync"]

crates/wasi/src/lib.rs

@@ -12,6 +12,14 @@ use std::rc::Rc;
 pub use wasi_common::{Error, WasiCtx, WasiCtxBuilder, WasiDir, WasiFile};
 use wasmtime::{Config, Linker, Store};
 
+/// Re-export the commonly used wasi-cap-std-sync crate here. This saves
+/// consumers of this library from having to keep additional dependencies
+/// in sync.
+#[cfg(feature = "sync")]
+pub mod sync {
+    pub use wasi_cap_std_sync::*;
+}
+
 /// An instantiated instance of all available wasi exports. Presently includes
 /// both the "preview1" snapshot and the "unstable" (preview0) snapshot.
 pub struct Wasi {