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|
use builtin_macros::builtins;
use std::{
collections::BTreeMap,
env, io,
rc::{Rc, Weak},
time::{SystemTime, UNIX_EPOCH},
};
use crate::{
compiler::GlobalsMap,
errors::ErrorKind,
observer::NoOpObserver,
spans::LightSpan,
value::{Builtin, BuiltinArgument, NixAttrs, Thunk},
vm::VM,
SourceCode, Value,
};
#[builtins]
mod impure_builtins {
use super::*;
use crate::builtins::coerce_value_to_path;
#[builtin("getEnv")]
fn builtin_get_env(_: &mut VM, var: Value) -> Result<Value, ErrorKind> {
Ok(env::var(var.to_str()?).unwrap_or_else(|_| "".into()).into())
}
#[builtin("pathExists")]
fn builtin_path_exists(vm: &mut VM, s: Value) -> Result<Value, ErrorKind> {
let path = coerce_value_to_path(&s, vm)?;
vm.io().path_exists(path).map(Value::Bool)
}
#[builtin("readDir")]
fn builtin_read_dir(vm: &mut VM, path: Value) -> Result<Value, ErrorKind> {
let path = coerce_value_to_path(&path, vm)?;
let mk_err = |err: io::Error| ErrorKind::IO {
path: Some(path.clone()),
error: Rc::new(err),
};
let res = path.read_dir().map_err(mk_err)?.into_iter().flat_map(
|entry| -> Result<(String, &str), ErrorKind> {
let entry = entry.map_err(mk_err)?;
let file_type = entry
.metadata()
.map_err(|err| ErrorKind::IO {
path: Some(entry.path()),
error: Rc::new(err),
})?
.file_type();
let val = if file_type.is_dir() {
"directory"
} else if file_type.is_file() {
"regular"
} else if file_type.is_symlink() {
"symlink"
} else {
"unknown"
};
Ok((entry.file_name().to_string_lossy().to_string(), val))
},
);
Ok(Value::attrs(NixAttrs::from_iter(res)))
}
#[builtin("readFile")]
fn builtin_read_file(vm: &mut VM, path: Value) -> Result<Value, ErrorKind> {
let path = coerce_value_to_path(&path, vm)?;
vm.io()
.read_to_string(path)
.map(|s| Value::String(s.into()))
}
}
/// Return all impure builtins, that is all builtins which may perform I/O
/// outside of the VM and so cannot be used in all contexts (e.g. WASM).
pub(super) fn builtins() -> BTreeMap<&'static str, Value> {
let mut map: BTreeMap<&'static str, Value> = impure_builtins::builtins()
.into_iter()
.map(|b| (b.name(), Value::Builtin(b)))
.collect();
// currentTime pins the time at which evaluation was started
{
let seconds = match SystemTime::now().duration_since(UNIX_EPOCH) {
Ok(dur) => dur.as_secs() as i64,
// This case is hit if the system time is *before* epoch.
Err(err) => -(err.duration().as_secs() as i64),
};
map.insert("currentTime", Value::Integer(seconds));
}
map
}
/// Constructs and inserts the `import` builtin. This builtin is special in that
/// it needs to capture the [crate::SourceCode] structure to correctly track
/// source code locations while invoking a compiler.
// TODO: need to be able to pass through a CompilationObserver, too.
pub fn builtins_import(globals: &Weak<GlobalsMap>, source: SourceCode) -> Builtin {
// This (very cheap, once-per-compiler-startup) clone exists
// solely in order to keep the borrow checker happy. It
// resolves the tension between the requirements of
// Rc::new_cyclic() and Builtin::new()
let globals = globals.clone();
Builtin::new(
"import",
&[BuiltinArgument {
strict: true,
name: "path",
}],
None,
move |mut args: Vec<Value>, vm: &mut VM| {
let mut path = super::coerce_value_to_path(&args.pop().unwrap(), vm)?;
if path.is_dir() {
path.push("default.nix");
}
let current_span = vm.current_span();
if let Some(cached) = vm.import_cache.get(&path) {
return Ok(cached.clone());
}
let contents = vm.io().read_to_string(path.clone())?;
let parsed = rnix::ast::Root::parse(&contents);
let errors = parsed.errors();
let file = source.add_file(path.to_string_lossy().to_string(), contents);
if !errors.is_empty() {
return Err(ErrorKind::ImportParseError {
path,
file,
errors: errors.to_vec(),
});
}
let result = crate::compiler::compile(
&parsed.tree().expr().unwrap(),
Some(path.clone()),
file,
// The VM must ensure that a strong reference to the
// globals outlives any self-references (which are
// weak) embedded within the globals. If the
// expect() below panics, it means that did not
// happen.
globals
.upgrade()
.expect("globals dropped while still in use"),
&mut NoOpObserver::default(),
)
.map_err(|err| ErrorKind::ImportCompilerError {
path: path.clone(),
errors: vec![err],
})?;
if !result.errors.is_empty() {
return Err(ErrorKind::ImportCompilerError {
path,
errors: result.errors,
});
}
// Compilation succeeded, we can construct a thunk from whatever it spat
// out and return that.
let res = Value::Thunk(Thunk::new_suspended(
result.lambda,
LightSpan::new_actual(current_span),
));
vm.import_cache.insert(path, res.clone());
for warning in result.warnings {
vm.push_warning(warning);
}
Ok(res)
},
)
}
|
