nixide/nix-bindings-flake/src/lib.rs
2025-12-05 16:55:09 -05:00

615 lines
19 KiB
Rust

use std::{ffi::CString, os::raw::c_char, ptr::NonNull};
use anyhow::{Context as _, Result};
use nix_bindings_bindgen_raw as raw;
use nix_bindings_expr::eval_state::EvalState;
use nix_bindings_fetchers::FetchersSettings;
use nix_bindings_util::{
context::{self, Context},
result_string_init,
string_return::{callback_get_result_string, callback_get_result_string_data},
};
/// Store settings for the flakes feature.
pub struct FlakeSettings {
pub(crate) ptr: *mut raw::flake_settings,
}
impl Drop for FlakeSettings {
fn drop(&mut self) {
unsafe {
raw::flake_settings_free(self.ptr);
}
}
}
impl FlakeSettings {
pub fn new() -> Result<Self> {
let mut ctx = Context::new();
let s = unsafe { context::check_call!(raw::flake_settings_new(&mut ctx)) }?;
Ok(FlakeSettings { ptr: s })
}
fn add_to_eval_state_builder(
&self,
builder: &mut nix_bindings_expr::eval_state::EvalStateBuilder,
) -> Result<()> {
let mut ctx = Context::new();
unsafe {
context::check_call!(raw::flake_settings_add_to_eval_state_builder(
&mut ctx,
self.ptr,
builder.raw_ptr()
))
}?;
Ok(())
}
}
pub trait EvalStateBuilderExt {
/// Configures the eval state to provide flakes features such as `builtins.getFlake`.
fn flakes(
self,
settings: &FlakeSettings,
) -> Result<nix_bindings_expr::eval_state::EvalStateBuilder>;
}
impl EvalStateBuilderExt for nix_bindings_expr::eval_state::EvalStateBuilder {
/// Configures the eval state to provide flakes features such as `builtins.getFlake`.
fn flakes(
mut self,
settings: &FlakeSettings,
) -> Result<nix_bindings_expr::eval_state::EvalStateBuilder> {
settings.add_to_eval_state_builder(&mut self)?;
Ok(self)
}
}
/// Parameters for parsing a flake reference.
pub struct FlakeReferenceParseFlags {
pub(crate) ptr: NonNull<raw::flake_reference_parse_flags>,
}
impl Drop for FlakeReferenceParseFlags {
fn drop(&mut self) {
unsafe {
raw::flake_reference_parse_flags_free(self.ptr.as_ptr());
}
}
}
impl FlakeReferenceParseFlags {
pub fn new(settings: &FlakeSettings) -> Result<Self> {
let mut ctx = Context::new();
let ptr = unsafe {
context::check_call!(raw::flake_reference_parse_flags_new(&mut ctx, settings.ptr))
}?;
let ptr = NonNull::new(ptr)
.context("flake_reference_parse_flags_new unexpectedly returned null")?;
Ok(FlakeReferenceParseFlags { ptr })
}
/// Sets the [base directory](https://nix.dev/manual/nix/latest/glossary#gloss-base-directory)
/// for resolving local flake references.
pub fn set_base_directory(&mut self, base_directory: &str) -> Result<()> {
let mut ctx = Context::new();
unsafe {
context::check_call!(raw::flake_reference_parse_flags_set_base_directory(
&mut ctx,
self.ptr.as_ptr(),
base_directory.as_ptr() as *const c_char,
base_directory.len()
))
}?;
Ok(())
}
}
pub struct FlakeReference {
pub(crate) ptr: NonNull<raw::flake_reference>,
}
impl Drop for FlakeReference {
fn drop(&mut self) {
unsafe {
raw::flake_reference_free(self.ptr.as_ptr());
}
}
}
impl FlakeReference {
/// Parse a flake reference from a string.
/// The string must be a valid flake reference, such as `github:owner/repo`.
/// It may also be suffixed with a `#` and a fragment, such as `github:owner/repo#something`,
/// in which case, the returned string will contain the fragment.
pub fn parse_with_fragment(
fetch_settings: &FetchersSettings,
flake_settings: &FlakeSettings,
flags: &FlakeReferenceParseFlags,
reference: &str,
) -> Result<(FlakeReference, String)> {
let mut ctx = Context::new();
let mut r = result_string_init!();
let mut ptr: *mut raw::flake_reference = std::ptr::null_mut();
unsafe {
context::check_call!(raw::flake_reference_and_fragment_from_string(
&mut ctx,
fetch_settings.raw_ptr(),
flake_settings.ptr,
flags.ptr.as_ptr(),
reference.as_ptr() as *const c_char,
reference.len(),
// pointer to ptr
&mut ptr,
Some(callback_get_result_string),
callback_get_result_string_data(&mut r)
))
}?;
let ptr = NonNull::new(ptr)
.context("flake_reference_and_fragment_from_string unexpectedly returned null")?;
Ok((FlakeReference { ptr: ptr }, r?))
}
}
/// Parameters that affect the locking of a flake.
pub struct FlakeLockFlags {
pub(crate) ptr: *mut raw::flake_lock_flags,
}
impl Drop for FlakeLockFlags {
fn drop(&mut self) {
unsafe {
raw::flake_lock_flags_free(self.ptr);
}
}
}
impl FlakeLockFlags {
pub fn new(settings: &FlakeSettings) -> Result<Self> {
let mut ctx = Context::new();
let s = unsafe { context::check_call!(raw::flake_lock_flags_new(&mut ctx, settings.ptr)) }?;
Ok(FlakeLockFlags { ptr: s })
}
/// Configures [LockedFlake::lock] to make incremental changes to the lock file as needed. Changes are written to file.
pub fn set_mode_write_as_needed(&mut self) -> Result<()> {
let mut ctx = Context::new();
unsafe {
context::check_call!(raw::flake_lock_flags_set_mode_write_as_needed(
&mut ctx, self.ptr
))
}?;
Ok(())
}
/// Make [LockedFlake::lock] check if the lock file is up to date. If not, an error is returned.
pub fn set_mode_check(&mut self) -> Result<()> {
let mut ctx = Context::new();
unsafe { context::check_call!(raw::flake_lock_flags_set_mode_check(&mut ctx, self.ptr)) }?;
Ok(())
}
/// Like `set_mode_write_as_needed`, but does not write to the lock file.
pub fn set_mode_virtual(&mut self) -> Result<()> {
let mut ctx = Context::new();
unsafe {
context::check_call!(raw::flake_lock_flags_set_mode_virtual(&mut ctx, self.ptr))
}?;
Ok(())
}
/// Adds an input override to the lock file that will be produced. The [LockedFlake::lock] operation will not write to the lock file.
pub fn add_input_override(
&mut self,
override_path: &str,
override_ref: &FlakeReference,
) -> Result<()> {
let mut ctx = Context::new();
unsafe {
context::check_call!(raw::flake_lock_flags_add_input_override(
&mut ctx,
self.ptr,
CString::new(override_path)
.context("Failed to create CString for override_path")?
.as_ptr(),
override_ref.ptr.as_ptr()
))
}?;
Ok(())
}
}
pub struct LockedFlake {
pub(crate) ptr: NonNull<raw::locked_flake>,
}
impl Drop for LockedFlake {
fn drop(&mut self) {
unsafe {
raw::locked_flake_free(self.ptr.as_ptr());
}
}
}
impl LockedFlake {
pub fn lock(
fetch_settings: &FetchersSettings,
flake_settings: &FlakeSettings,
eval_state: &EvalState,
flags: &FlakeLockFlags,
flake_ref: &FlakeReference,
) -> Result<LockedFlake> {
let mut ctx = Context::new();
let ptr = unsafe {
context::check_call!(raw::flake_lock(
&mut ctx,
fetch_settings.raw_ptr(),
flake_settings.ptr,
eval_state.raw_ptr(),
flags.ptr,
flake_ref.ptr.as_ptr()
))
}?;
let ptr = NonNull::new(ptr).context("flake_lock unexpectedly returned null")?;
Ok(LockedFlake { ptr })
}
/// Returns the outputs of the flake - the result of calling the `outputs` attribute.
pub fn outputs(
&self,
flake_settings: &FlakeSettings,
eval_state: &mut EvalState,
) -> Result<nix_bindings_expr::value::Value> {
let mut ctx = Context::new();
unsafe {
let r = context::check_call!(raw::locked_flake_get_output_attrs(
&mut ctx,
flake_settings.ptr,
eval_state.raw_ptr(),
self.ptr.as_ptr()
))?;
Ok(nix_bindings_expr::value::__private::raw_value_new(r))
}
}
}
#[cfg(test)]
mod tests {
use nix_bindings_expr::eval_state::{gc_register_my_thread, EvalStateBuilder};
use nix_bindings_store::store::Store;
use super::*;
use std::sync::Once;
static INIT: Once = Once::new();
fn init() {
// Only set experimental-features once to minimize the window where
// concurrent Nix operations might read the setting while it's being modified
INIT.call_once(|| {
nix_bindings_expr::eval_state::init().unwrap();
nix_bindings_util::settings::set("experimental-features", "flakes").unwrap();
});
}
#[test]
fn flake_settings_getflake_exists() {
init();
let gc_registration = gc_register_my_thread();
let store = Store::open(None, []).unwrap();
let mut eval_state = EvalStateBuilder::new(store)
.unwrap()
.flakes(&FlakeSettings::new().unwrap())
.unwrap()
.build()
.unwrap();
let v = eval_state
.eval_from_string("builtins?getFlake", "<test>")
.unwrap();
let b = eval_state.require_bool(&v).unwrap();
assert_eq!(b, true);
drop(gc_registration);
}
#[test]
fn flake_lock_load_flake() {
init();
let gc_registration = gc_register_my_thread();
let store = Store::open(None, []).unwrap();
let fetchers_settings = FetchersSettings::new().unwrap();
let flake_settings = FlakeSettings::new().unwrap();
let mut eval_state = EvalStateBuilder::new(store)
.unwrap()
.flakes(&flake_settings)
.unwrap()
.build()
.unwrap();
let tmp_dir = tempfile::tempdir().unwrap();
// Create flake.nix
let flake_nix = tmp_dir.path().join("flake.nix");
std::fs::write(
&flake_nix,
r#"
{
outputs = { ... }: {
hello = "potato";
};
}
"#,
)
.unwrap();
let flake_lock_flags = FlakeLockFlags::new(&flake_settings).unwrap();
let (flake_ref, fragment) = FlakeReference::parse_with_fragment(
&fetchers_settings,
&flake_settings,
&FlakeReferenceParseFlags::new(&flake_settings).unwrap(),
&format!("path:{}#subthing", tmp_dir.path().display()),
)
.unwrap();
assert_eq!(fragment, "subthing");
let locked_flake = LockedFlake::lock(
&fetchers_settings,
&flake_settings,
&eval_state,
&flake_lock_flags,
&flake_ref,
)
.unwrap();
let outputs = locked_flake
.outputs(&flake_settings, &mut eval_state)
.unwrap();
let hello = eval_state.require_attrs_select(&outputs, &"hello").unwrap();
let hello = eval_state.require_string(&hello).unwrap();
assert_eq!(hello, "potato");
drop(fetchers_settings);
drop(tmp_dir);
drop(gc_registration);
}
#[test]
fn flake_lock_load_flake_with_flags() {
init();
let gc_registration = gc_register_my_thread();
let store = Store::open(None, []).unwrap();
let fetchers_settings = FetchersSettings::new().unwrap();
let flake_settings = FlakeSettings::new().unwrap();
let mut eval_state = EvalStateBuilder::new(store)
.unwrap()
.flakes(&flake_settings)
.unwrap()
.build()
.unwrap();
let tmp_dir = tempfile::tempdir().unwrap();
let flake_dir_a = tmp_dir.path().join("a");
let flake_dir_b = tmp_dir.path().join("b");
let flake_dir_c = tmp_dir.path().join("c");
std::fs::create_dir_all(&flake_dir_a).unwrap();
std::fs::create_dir_all(&flake_dir_b).unwrap();
std::fs::create_dir_all(&flake_dir_c).unwrap();
let flake_dir_a_str = flake_dir_a.to_str().unwrap();
let flake_dir_c_str = flake_dir_c.to_str().unwrap();
assert!(!flake_dir_a_str.is_empty());
assert!(!flake_dir_c_str.is_empty());
// a
std::fs::write(
&tmp_dir.path().join("a/flake.nix"),
r#"
{
inputs.b.url = "@flake_dir_b@";
outputs = { b, ... }: {
hello = b.hello;
};
}
"#
.replace("@flake_dir_b@", flake_dir_b.to_str().unwrap()),
)
.unwrap();
// b
std::fs::write(
&tmp_dir.path().join("b/flake.nix"),
r#"
{
outputs = { ... }: {
hello = "BOB";
};
}
"#,
)
.unwrap();
// c
std::fs::write(
&tmp_dir.path().join("c/flake.nix"),
r#"
{
outputs = { ... }: {
hello = "Claire";
};
}
"#,
)
.unwrap();
let mut flake_lock_flags = FlakeLockFlags::new(&flake_settings).unwrap();
let mut flake_reference_parse_flags =
FlakeReferenceParseFlags::new(&flake_settings).unwrap();
flake_reference_parse_flags
.set_base_directory(tmp_dir.path().to_str().unwrap())
.unwrap();
let (flake_ref_a, fragment) = FlakeReference::parse_with_fragment(
&fetchers_settings,
&flake_settings,
&flake_reference_parse_flags,
&format!("path:{}", &flake_dir_a_str),
)
.unwrap();
assert_eq!(fragment, "");
// Step 1: Do not update (check), fails
flake_lock_flags.set_mode_check().unwrap();
let locked_flake = LockedFlake::lock(
&fetchers_settings,
&flake_settings,
&eval_state,
&flake_lock_flags,
&flake_ref_a,
);
// Has not been locked and would need to write a lock file.
assert!(locked_flake.is_err());
let saved_err = match locked_flake {
Ok(_) => panic!("Expected error, but got Ok"),
Err(e) => e,
};
// Step 2: Update but do not write, succeeds
flake_lock_flags.set_mode_virtual().unwrap();
let locked_flake = LockedFlake::lock(
&fetchers_settings,
&flake_settings,
&eval_state,
&flake_lock_flags,
&flake_ref_a,
)
.unwrap();
let outputs = locked_flake
.outputs(&flake_settings, &mut eval_state)
.unwrap();
let hello = eval_state.require_attrs_select(&outputs, &"hello").unwrap();
let hello = eval_state.require_string(&hello).unwrap();
assert_eq!(hello, "BOB");
// Step 3: The lock was not written, so Step 1 would fail again
flake_lock_flags.set_mode_check().unwrap();
let locked_flake = LockedFlake::lock(
&fetchers_settings,
&flake_settings,
&eval_state,
&flake_lock_flags,
&flake_ref_a,
);
// Has not been locked and would need to write a lock file.
assert!(locked_flake.is_err());
match locked_flake {
Ok(_) => panic!("Expected error, but got Ok"),
Err(e) => {
assert_eq!(e.to_string(), saved_err.to_string());
}
};
// Step 4: Update and write, succeeds
flake_lock_flags.set_mode_write_as_needed().unwrap();
let locked_flake = LockedFlake::lock(
&fetchers_settings,
&flake_settings,
&eval_state,
&flake_lock_flags,
&flake_ref_a,
)
.unwrap();
let outputs = locked_flake
.outputs(&flake_settings, &mut eval_state)
.unwrap();
let hello = eval_state.require_attrs_select(&outputs, &"hello").unwrap();
let hello = eval_state.require_string(&hello).unwrap();
assert_eq!(hello, "BOB");
// Step 5: Lock was written, so Step 1 succeeds
flake_lock_flags.set_mode_check().unwrap();
let locked_flake = LockedFlake::lock(
&fetchers_settings,
&flake_settings,
&eval_state,
&flake_lock_flags,
&flake_ref_a,
)
.unwrap();
let outputs = locked_flake
.outputs(&flake_settings, &mut eval_state)
.unwrap();
let hello = eval_state.require_attrs_select(&outputs, &"hello").unwrap();
let hello = eval_state.require_string(&hello).unwrap();
assert_eq!(hello, "BOB");
// Step 6: Lock with override, do not write
// This shouldn't matter; write_as_needed will be overridden
flake_lock_flags.set_mode_write_as_needed().unwrap();
let (flake_ref_c, fragment) = FlakeReference::parse_with_fragment(
&fetchers_settings,
&flake_settings,
&flake_reference_parse_flags,
&format!("path:{}", &flake_dir_c_str),
)
.unwrap();
assert_eq!(fragment, "");
flake_lock_flags
.add_input_override("b", &flake_ref_c)
.unwrap();
let locked_flake = LockedFlake::lock(
&fetchers_settings,
&flake_settings,
&eval_state,
&flake_lock_flags,
&flake_ref_a,
)
.unwrap();
let outputs = locked_flake
.outputs(&flake_settings, &mut eval_state)
.unwrap();
let hello = eval_state.require_attrs_select(&outputs, &"hello").unwrap();
let hello = eval_state.require_string(&hello).unwrap();
assert_eq!(hello, "Claire");
// Can't delete overrides, so trash it
let mut flake_lock_flags = FlakeLockFlags::new(&flake_settings).unwrap();
// Step 7: Override was not written; lock still points to b
flake_lock_flags.set_mode_check().unwrap();
let locked_flake = LockedFlake::lock(
&fetchers_settings,
&flake_settings,
&eval_state,
&flake_lock_flags,
&flake_ref_a,
)
.unwrap();
let outputs = locked_flake
.outputs(&flake_settings, &mut eval_state)
.unwrap();
let hello = eval_state.require_attrs_select(&outputs, &"hello").unwrap();
let hello = eval_state.require_string(&hello).unwrap();
assert_eq!(hello, "BOB");
drop(fetchers_settings);
drop(tmp_dir);
drop(gc_registration);
}
}