diff options
Diffstat (limited to 'tvix/glue/src/builtins/derivation.rs')
| -rw-r--r-- | tvix/glue/src/builtins/derivation.rs | 471 |
1 files changed, 471 insertions, 0 deletions
diff --git a/tvix/glue/src/builtins/derivation.rs b/tvix/glue/src/builtins/derivation.rs new file mode 100644 index 000000000000..4eb0141d544b --- /dev/null +++ b/tvix/glue/src/builtins/derivation.rs @@ -0,0 +1,471 @@ +//! Implements `builtins.derivation`, the core of what makes Nix build packages. +use crate::builtins::DerivationError; +use crate::known_paths::{KnownPaths, PathKind, PathName}; +use nix_compat::derivation::{Derivation, Output}; +use nix_compat::nixhash; +use std::cell::RefCell; +use std::collections::{btree_map, BTreeSet}; +use std::rc::Rc; +use tvix_eval::builtin_macros::builtins; +use tvix_eval::generators::{self, emit_warning_kind, GenCo}; +use tvix_eval::{ + AddContext, CatchableErrorKind, CoercionKind, ErrorKind, NixAttrs, NixList, Value, WarningKind, +}; + +// Constants used for strangely named fields in derivation inputs. +const STRUCTURED_ATTRS: &str = "__structuredAttrs"; +const IGNORE_NULLS: &str = "__ignoreNulls"; + +/// Helper function for populating the `drv.outputs` field from a +/// manually specified set of outputs, instead of the default +/// `outputs`. +async fn populate_outputs( + co: &GenCo, + drv: &mut Derivation, + outputs: NixList, +) -> Result<(), ErrorKind> { + // Remove the original default `out` output. + drv.outputs.clear(); + + for output in outputs { + let output_name = generators::request_force(co, output) + .await + .to_str() + .context("determining output name")?; + + if drv + .outputs + .insert(output_name.as_str().into(), Default::default()) + .is_some() + { + return Err(DerivationError::DuplicateOutput(output_name.as_str().into()).into()); + } + } + + Ok(()) +} + +/// Populate the inputs of a derivation from the build references +/// found when scanning the derivation's parameters. +fn populate_inputs<I: IntoIterator<Item = PathName>>( + drv: &mut Derivation, + known_paths: &KnownPaths, + references: I, +) { + for reference in references.into_iter() { + let reference = &known_paths[&reference]; + match &reference.kind { + PathKind::Plain => { + drv.input_sources.insert(reference.path.clone()); + } + + PathKind::Output { name, derivation } => { + match drv.input_derivations.entry(derivation.clone()) { + btree_map::Entry::Vacant(entry) => { + entry.insert(BTreeSet::from([name.clone()])); + } + + btree_map::Entry::Occupied(mut entry) => { + entry.get_mut().insert(name.clone()); + } + } + } + + PathKind::Derivation { output_names } => { + match drv.input_derivations.entry(reference.path.clone()) { + btree_map::Entry::Vacant(entry) => { + entry.insert(output_names.clone()); + } + + btree_map::Entry::Occupied(mut entry) => { + entry.get_mut().extend(output_names.clone().into_iter()); + } + } + } + } + } +} + +/// Populate the output configuration of a derivation based on the +/// parameters passed to the call, configuring a fixed-output derivation output +/// if necessary. +/// +/// This function handles all possible combinations of the +/// parameters, including invalid ones. +/// +/// Due to the support for SRI hashes, and how these are passed along to +/// builtins.derivation, outputHash and outputHashAlgo can have values which +/// need to be further modified before constructing the Derivation struct. +/// +/// If outputHashAlgo is an SRI hash, outputHashAlgo must either be an empty +/// string, or the hash algorithm as specified in the (single) SRI (entry). +/// SRI strings with multiple hash algorithms are not supported. +/// +/// In case an SRI string was used, the (single) fixed output is populated +/// with the hash algo name, and the hash digest is populated with the +/// (lowercase) hex encoding of the digest. +/// +/// These values are only rewritten for the outputs, not what's passed to env. +fn handle_fixed_output( + drv: &mut Derivation, + hash_str: Option<String>, // in nix: outputHash + hash_algo_str: Option<String>, // in nix: outputHashAlgo + hash_mode_str: Option<String>, // in nix: outputHashmode +) -> Result<(), ErrorKind> { + // If outputHash is provided, ensure hash_algo_str is compatible. + // If outputHash is not provided, do nothing. + if let Some(hash_str) = hash_str { + // treat an empty algo as None + let hash_algo_str = match hash_algo_str { + Some(s) if s.is_empty() => None, + Some(s) => Some(s), + None => None, + }; + + // construct a NixHash. + let nixhash = nixhash::from_str(&hash_str, hash_algo_str.as_deref()) + .map_err(DerivationError::InvalidOutputHash)?; + + // construct the fixed output. + drv.outputs.insert( + "out".to_string(), + Output { + path: "".to_string(), + ca_hash: match hash_mode_str.as_deref() { + None | Some("flat") => Some(nixhash::CAHash::Flat(nixhash)), + Some("recursive") => Some(nixhash::CAHash::Nar(nixhash)), + Some(other) => { + return Err(DerivationError::InvalidOutputHashMode(other.to_string()))? + } + }, + }, + ); + } + Ok(()) +} + +/// Handles derivation parameters which are not just forwarded to +/// the environment. The return value indicates whether the +/// parameter should be included in the environment. +async fn handle_derivation_parameters( + drv: &mut Derivation, + co: &GenCo, + name: &str, + value: &Value, + val_str: &str, +) -> Result<Result<bool, CatchableErrorKind>, ErrorKind> { + match name { + IGNORE_NULLS => return Ok(Ok(false)), + + // Command line arguments to the builder. + "args" => { + let args = value.to_list()?; + for arg in args { + match strong_coerce_to_string(co, arg).await? { + Err(cek) => return Ok(Err(cek)), + Ok(s) => drv.arguments.push(s), + } + } + + // The arguments do not appear in the environment. + return Ok(Ok(false)); + } + + // Explicitly specified drv outputs (instead of default [ "out" ]) + "outputs" => { + let outputs = value + .to_list() + .context("looking at the `outputs` parameter of the derivation")?; + + populate_outputs(co, drv, outputs).await?; + } + + "builder" => { + drv.builder = val_str.to_string(); + } + + "system" => { + drv.system = val_str.to_string(); + } + + _ => {} + } + + Ok(Ok(true)) +} + +async fn strong_coerce_to_string( + co: &GenCo, + val: Value, +) -> Result<Result<String, CatchableErrorKind>, ErrorKind> { + let val = generators::request_force(co, val).await; + match generators::request_string_coerce(co, val, CoercionKind::Strong).await { + Err(cek) => Ok(Err(cek)), + Ok(val_str) => Ok(Ok(val_str.as_str().to_string())), + } +} + +#[builtins(state = "Rc<RefCell<KnownPaths>>")] +pub(crate) mod derivation_builtins { + use super::*; + use nix_compat::store_path::hash_placeholder; + use tvix_eval::generators::Gen; + + #[builtin("placeholder")] + async fn builtin_placeholder(co: GenCo, input: Value) -> Result<Value, ErrorKind> { + let placeholder = hash_placeholder( + input + .to_str() + .context("looking at output name in builtins.placeholder")? + .as_str(), + ); + + Ok(placeholder.into()) + } + + /// Strictly construct a Nix derivation from the supplied arguments. + /// + /// This is considered an internal function, users usually want to + /// use the higher-level `builtins.derivation` instead. + #[builtin("derivationStrict")] + async fn builtin_derivation_strict( + state: Rc<RefCell<KnownPaths>>, + co: GenCo, + input: Value, + ) -> Result<Value, ErrorKind> { + let input = input.to_attrs()?; + let name = generators::request_force(&co, input.select_required("name")?.clone()) + .await + .to_str() + .context("determining derivation name")?; + + if name.is_empty() { + return Err(ErrorKind::Abort("derivation has empty name".to_string())); + } + + // Check whether attributes should be passed as a JSON file. + // TODO: the JSON serialisation has to happen here. + if let Some(sa) = input.select(STRUCTURED_ATTRS) { + if generators::request_force(&co, sa.clone()).await.as_bool()? { + return Err(ErrorKind::NotImplemented(STRUCTURED_ATTRS)); + } + } + + // Check whether null attributes should be ignored or passed through. + let ignore_nulls = match input.select(IGNORE_NULLS) { + Some(b) => generators::request_force(&co, b.clone()).await.as_bool()?, + None => false, + }; + + let mut drv = Derivation::default(); + drv.outputs.insert("out".to_string(), Default::default()); + + async fn select_string( + co: &GenCo, + attrs: &NixAttrs, + key: &str, + ) -> Result<Result<Option<String>, CatchableErrorKind>, ErrorKind> { + if let Some(attr) = attrs.select(key) { + match strong_coerce_to_string(co, attr.clone()).await? { + Err(cek) => return Ok(Err(cek)), + Ok(str) => return Ok(Ok(Some(str))), + } + } + + Ok(Ok(None)) + } + + for (name, value) in input.clone().into_iter_sorted() { + let value = generators::request_force(&co, value).await; + if ignore_nulls && matches!(value, Value::Null) { + continue; + } + + match strong_coerce_to_string(&co, value.clone()).await? { + Err(cek) => return Ok(Value::Catchable(cek)), + Ok(val_str) => { + // handle_derivation_parameters tells us whether the + // argument should be added to the environment; continue + // to the next one otherwise + match handle_derivation_parameters( + &mut drv, + &co, + name.as_str(), + &value, + &val_str, + ) + .await? + { + Err(cek) => return Ok(Value::Catchable(cek)), + Ok(false) => continue, + _ => (), + } + + // Most of these are also added to the builder's environment in "raw" form. + if drv + .environment + .insert(name.as_str().to_string(), val_str.into()) + .is_some() + { + return Err( + DerivationError::DuplicateEnvVar(name.as_str().to_string()).into() + ); + } + } + } + } + + // Configure fixed-output derivations if required. + { + let output_hash = match select_string(&co, &input, "outputHash") + .await + .context("evaluating the `outputHash` parameter")? + { + Err(cek) => return Ok(Value::Catchable(cek)), + Ok(s) => s, + }; + let output_hash_algo = match select_string(&co, &input, "outputHashAlgo") + .await + .context("evaluating the `outputHashAlgo` parameter")? + { + Err(cek) => return Ok(Value::Catchable(cek)), + Ok(s) => s, + }; + let output_hash_mode = match select_string(&co, &input, "outputHashMode") + .await + .context("evaluating the `outputHashMode` parameter")? + { + Err(cek) => return Ok(Value::Catchable(cek)), + Ok(s) => s, + }; + handle_fixed_output(&mut drv, output_hash, output_hash_algo, output_hash_mode)?; + } + + // Scan references in relevant attributes to detect any build-references. + let references = { + let state = state.borrow(); + if state.is_empty() { + // skip reference scanning, create an empty result + Default::default() + } else { + let mut refscan = state.reference_scanner(); + drv.arguments.iter().for_each(|s| refscan.scan(s)); + drv.environment.values().for_each(|s| refscan.scan(s)); + refscan.scan(&drv.builder); + refscan.finalise() + } + }; + + // Each output name needs to exist in the environment, at this + // point initialised as an empty string because that is the + // way of Golang ;) + for output in drv.outputs.keys() { + if drv + .environment + .insert(output.to_string(), String::new().into()) + .is_some() + { + emit_warning_kind(&co, WarningKind::ShadowedOutput(output.to_string())).await; + } + } + + let mut known_paths = state.borrow_mut(); + populate_inputs(&mut drv, &known_paths, references); + + // At this point, derivation fields are fully populated from + // eval data structures. + drv.validate(false) + .map_err(DerivationError::InvalidDerivation)?; + + // Calculate the derivation_or_fod_hash for the current derivation. + // This one is still intermediate (so not added to known_paths) + let derivation_or_fod_hash_tmp = + drv.derivation_or_fod_hash(|drv| known_paths.get_hash_derivation_modulo(drv)); + + // Mutate the Derivation struct and set output paths + drv.calculate_output_paths(&name, &derivation_or_fod_hash_tmp) + .map_err(DerivationError::InvalidDerivation)?; + + let derivation_path = drv + .calculate_derivation_path(&name) + .map_err(DerivationError::InvalidDerivation)?; + + // recompute the hash derivation modulo and add to known_paths + let derivation_or_fod_hash_final = + drv.derivation_or_fod_hash(|drv| known_paths.get_hash_derivation_modulo(drv)); + + known_paths.add_hash_derivation_modulo( + derivation_path.to_absolute_path(), + &derivation_or_fod_hash_final, + ); + + // mark all the new paths as known + let output_names: Vec<String> = drv.outputs.keys().map(Clone::clone).collect(); + known_paths.drv(derivation_path.to_absolute_path(), &output_names); + + for (output_name, output) in &drv.outputs { + known_paths.output( + &output.path, + output_name, + derivation_path.to_absolute_path(), + ); + } + + let mut new_attrs: Vec<(String, String)> = drv + .outputs + .into_iter() + .map(|(name, output)| (name, output.path)) + .collect(); + + new_attrs.push(("drvPath".to_string(), derivation_path.to_absolute_path())); + + Ok(Value::Attrs(Box::new(NixAttrs::from_iter( + new_attrs.into_iter(), + )))) + } + + #[builtin("toFile")] + async fn builtin_to_file( + state: Rc<RefCell<KnownPaths>>, + co: GenCo, + name: Value, + content: Value, + ) -> Result<Value, ErrorKind> { + let name = name + .to_str() + .context("evaluating the `name` parameter of builtins.toFile")?; + let content = content + .to_str() + .context("evaluating the `content` parameter of builtins.toFile")?; + + let mut refscan = state.borrow().reference_scanner(); + refscan.scan(content.as_str()); + let refs = { + let paths = state.borrow(); + refscan + .finalise() + .into_iter() + .map(|path| paths[&path].path.to_string()) + .collect::<Vec<_>>() + }; + + // TODO: fail on derivation references (only "plain" is allowed here) + + let path = nix_compat::store_path::build_text_path(name.as_str(), content.as_str(), refs) + .map_err(|_e| { + nix_compat::derivation::DerivationError::InvalidOutputName( + name.as_str().to_string(), + ) + }) + .map_err(DerivationError::InvalidDerivation)? + .to_absolute_path(); + + state.borrow_mut().plain(&path); + + // TODO: actually persist the file in the store at that path ... + + Ok(Value::String(path.into())) + } +} + +pub use derivation_builtins::builtins as derivation_builtins; |