wasi-cap-std-sync 17.0.3

//! The `wasi-cap-std-sync` crate provides impl of `WasiFile` and `WasiDir` in
//! terms of `cap_std::fs::{File, Dir}`. These types provide sandboxed access
//! to the local filesystem on both Unix and Windows.
//!
//! All syscalls are hidden behind the `cap-std` hierarchy, with the lone
//! exception of the `sched` implementation, which is provided for both unix
//! and windows in separate modules.
//!
//! Any `wasi_common::{WasiCtx, WasiCtxBuilder}` is interoperable with the
//! `wasi-cap-std-sync` crate. However, for convenience, `wasi-cap-std-sync`
//! provides its own `WasiCtxBuilder` that hooks up to all of the crate's
//! components, i.e. it fills in all of the arguments to
//! `WasiCtx::builder(...)`, presents `preopen_dir` in terms of
//! `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
//! on Rust `Future`s, async impls will be able to interoperate, but the
//! synchronous scheduler depends on downcasting the `WasiFile` type down to
//! concrete types it knows about (which in turn impl `AsFd` for passing to
//! unix `poll`, or the analogous traits on windows).
//!
//! Why is this impl suffixed with `-sync`? Because `async` is coming soon!
//! The async impl may end up depending on tokio or other relatively heavy
//! deps, so we will retain a sync implementation so that wasi-common users
//! have an option of not pulling in an async runtime.

#![cfg_attr(io_lifetimes_use_std, feature(io_safety))]

pub mod clocks;
pub mod dir;
pub mod file;
pub mod net;
pub mod sched;
pub mod stdio;

pub use cap_std::ambient_authority;
pub use cap_std::fs::Dir;
pub use cap_std::net::TcpListener;
pub use clocks::clocks_ctx;
pub use sched::sched_ctx;

use crate::net::Socket;
use cap_rand::{Rng, RngCore, SeedableRng};
use std::mem;
use std::path::Path;
use wasi_common::{file::FileAccessMode, table::Table, Error, WasiCtx, WasiFile};

pub struct WasiCtxBuilder {
    ctx: WasiCtx,
    built: bool,
}

impl WasiCtxBuilder {
    pub fn new() -> Self {
        WasiCtxBuilder {
            ctx: WasiCtx::new(random_ctx(), clocks_ctx(), sched_ctx(), Table::new()),
            built: false,
        }
    }
    pub fn env(
        &mut self,
        var: &str,
        value: &str,
    ) -> Result<&mut Self, wasi_common::StringArrayError> {
        self.ctx.push_env(var, value)?;
        Ok(self)
    }
    pub fn envs(
        &mut self,
        env: &[(String, String)],
    ) -> Result<&mut Self, wasi_common::StringArrayError> {
        for (k, v) in env {
            self.ctx.push_env(k, v)?;
        }
        Ok(self)
    }
    pub fn inherit_env(&mut self) -> Result<&mut Self, wasi_common::StringArrayError> {
        for (key, value) in std::env::vars() {
            self.ctx.push_env(&key, &value)?;
        }
        Ok(self)
    }
    pub fn arg(&mut self, arg: &str) -> Result<&mut Self, wasi_common::StringArrayError> {
        self.ctx.push_arg(arg)?;
        Ok(self)
    }
    pub fn args(&mut self, arg: &[String]) -> Result<&mut Self, wasi_common::StringArrayError> {
        for a in arg {
            self.ctx.push_arg(&a)?;
        }
        Ok(self)
    }
    pub fn inherit_args(&mut self) -> Result<&mut Self, wasi_common::StringArrayError> {
        for arg in std::env::args() {
            self.ctx.push_arg(&arg)?;
        }
        Ok(self)
    }
    pub fn stdin(&mut self, f: Box<dyn WasiFile>) -> &mut Self {
        self.ctx.set_stdin(f);
        self
    }
    pub fn stdout(&mut self, f: Box<dyn WasiFile>) -> &mut Self {
        self.ctx.set_stdout(f);
        self
    }
    pub fn stderr(&mut self, f: Box<dyn WasiFile>) -> &mut Self {
        self.ctx.set_stderr(f);
        self
    }
    pub fn inherit_stdin(&mut self) -> &mut Self {
        self.stdin(Box::new(crate::stdio::stdin()))
    }
    pub fn inherit_stdout(&mut self) -> &mut Self {
        self.stdout(Box::new(crate::stdio::stdout()))
    }
    pub fn inherit_stderr(&mut self) -> &mut Self {
        self.stderr(Box::new(crate::stdio::stderr()))
    }
    pub fn inherit_stdio(&mut self) -> &mut Self {
        self.inherit_stdin().inherit_stdout().inherit_stderr()
    }
    pub fn preopened_dir(
        &mut self,
        dir: Dir,
        guest_path: impl AsRef<Path>,
    ) -> Result<&mut Self, Error> {
        let dir = Box::new(crate::dir::Dir::from_cap_std(dir));
        self.ctx.push_preopened_dir(dir, guest_path)?;
        Ok(self)
    }
    pub fn preopened_socket(
        &mut self,
        fd: u32,
        socket: impl Into<Socket>,
    ) -> Result<&mut Self, Error> {
        let socket: Socket = socket.into();
        let file: Box<dyn WasiFile> = socket.into();
        self.ctx
            .insert_file(fd, file, FileAccessMode::READ | FileAccessMode::WRITE);
        Ok(self)
    }
    pub fn build(&mut self) -> WasiCtx {
        assert!(!self.built);
        let WasiCtxBuilder { ctx, .. } = mem::replace(self, Self::new());
        self.built = true;
        ctx
    }
}

pub fn random_ctx() -> Box<dyn RngCore + Send + Sync> {
    let mut rng = cap_rand::thread_rng(cap_rand::ambient_authority());
    Box::new(cap_rand::rngs::StdRng::from_seed(rng.gen()))
}