feat(tvix/cli): implement NixCompatIO helper type

This type allows for temporarily compatibility with the C++ Nix store,
specifically (for now) it gives us the store directory used by Nix and
imports files the same way.

Change-Id: I4767794ef2863eba49661315c63c4e17de946d60
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7587
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI
This commit is contained in:
Vincent Ambo 2022-12-13 20:17:00 +03:00 committed by tazjin
parent 4714f8b939
commit ea7d63e177
6 changed files with 92 additions and 2 deletions

1
tvix/Cargo.lock generated
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@ -1493,6 +1493,7 @@ dependencies = [
"clap 4.0.27",
"dirs",
"rustyline",
"smol_str",
"tvix-eval",
]

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@ -4229,6 +4229,10 @@ rec {
name = "rustyline";
packageId = "rustyline";
}
{
name = "smol_str";
packageId = "smol_str";
}
{
name = "tvix-eval";
packageId = "tvix-eval";

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@ -12,3 +12,4 @@ tvix-eval = { path = "../eval" }
rustyline = "10.0.0"
clap = { version = "4.0", features = ["derive", "env"] }
dirs = "4.0.0"
smol_str = "0.1"

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@ -1,3 +1,5 @@
mod nix_compat;
use std::{fs, path::PathBuf};
use clap::Parser;
@ -39,7 +41,7 @@ struct Args {
/// evaluation succeeded.
fn interpret(code: &str, path: Option<PathBuf>, args: &Args) -> bool {
let mut eval = tvix_eval::Evaluation::new(code, path);
eval.io_handle = Box::new(tvix_eval::StdIO);
eval.io_handle = Box::new(nix_compat::NixCompatIO::new());
eval.nix_path = args.nix_search_path.clone();
let source_map = eval.source_map();

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@ -0,0 +1,82 @@
//! This module implements (temporary) compatibility shims between
//! Tvix and C++ Nix.
//!
//! These are not intended to be long-lived, but should bootstrap Tvix
//! by piggybacking off functionality that already exists in Nix and
//! is still being implemented in Tvix.
use std::path::Path;
use std::process::Command;
use std::{io, path::PathBuf};
use smol_str::SmolStr;
use tvix_eval::{ErrorKind, EvalIO, FileType, StdIO};
/// Compatibility implementation of [`EvalIO`] that uses C++ Nix to
/// write files to the Nix store.
pub struct NixCompatIO {
/// Most IO requests are tunneled through to [`tvix_eval::StdIO`]
/// instead.
underlying: StdIO,
}
impl NixCompatIO {
pub fn new() -> Self {
NixCompatIO { underlying: StdIO }
}
}
impl EvalIO for NixCompatIO {
fn store_dir(&self) -> Option<String> {
Some("/nix/store".into())
}
// Pass path imports through to `nix-store --add`
fn import_path(&self, path: &Path) -> Result<PathBuf, ErrorKind> {
add_to_store(path).map_err(|error| ErrorKind::IO {
error: std::rc::Rc::new(error),
path: Some(path.to_path_buf()),
})
}
// Pass the rest of the functions through to `Self::underlying`
fn path_exists(&self, path: PathBuf) -> Result<bool, ErrorKind> {
self.underlying.path_exists(path)
}
fn read_to_string(&self, path: PathBuf) -> Result<String, ErrorKind> {
self.underlying.read_to_string(path)
}
fn read_dir(&self, path: PathBuf) -> Result<Vec<(SmolStr, FileType)>, ErrorKind> {
self.underlying.read_dir(path)
}
}
/// Add a path to the Nix store using the `nix-store --add`
/// functionality from C++ Nix.
fn add_to_store(path: &Path) -> Result<PathBuf, io::Error> {
if !path.try_exists()? {
return Err(io::Error::from(io::ErrorKind::NotFound));
}
let mut cmd = Command::new("nix-store");
cmd.arg("--add");
cmd.arg(path);
let out = cmd.output()?;
if !out.status.success() {
return Err(io::Error::new(
io::ErrorKind::Other,
String::from_utf8_lossy(&out.stderr),
));
}
let out_path_str = String::from_utf8(out.stdout)
.map_err(|err| io::Error::new(io::ErrorKind::InvalidData, err))?;
let mut out_path = PathBuf::new();
out_path.push(out_path_str.trim());
Ok(out_path)
}

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@ -45,7 +45,7 @@ use std::sync::Arc;
pub use crate::builtins::global_builtins;
pub use crate::compiler::{compile, prepare_globals};
pub use crate::errors::{Error, ErrorKind, EvalResult};
pub use crate::io::{DummyIO, EvalIO};
pub use crate::io::{DummyIO, EvalIO, FileType};
use crate::observer::{CompilerObserver, RuntimeObserver};
pub use crate::pretty_ast::pretty_print_expr;
pub use crate::source::SourceCode;