//! Implements `builtins.derivation`, the core of what makes Nix build packages.
use crate::builtins::DerivationError;
use crate::tvix_store_io::TvixStoreIO;
use bstr::BString;
use nix_compat::derivation::{Derivation, Output};
use nix_compat::nixhash;
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, NixContext,
NixContextElement, Value, WarningKind,
};
// Constants used for strangely named fields in derivation inputs.
const STRUCTURED_ATTRS: &str = "__structuredAttrs";
const IGNORE_NULLS: &str = "__ignoreNulls";
/// Populate the inputs of a derivation from the build references
/// found when scanning the derivation's parameters and extracting their contexts.
fn populate_inputs(drv: &mut Derivation, full_context: NixContext) {
for element in full_context.iter() {
match element {
NixContextElement::Plain(source) => {
drv.input_sources.insert(source.clone());
}
NixContextElement::Single { 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());
}
}
}
NixContextElement::Derivation(_drv_path) => {
// This is a hard one, it means that
// we are depending on a drvPath of ourselves
// *or* another derivation's drvPath.
// What to do here?
panic!("please do not depend on drvPath, I have 2 hours of sleep in blood");
}
}
}
}
/// 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.
///
/// The return value may optionally contain a warning.
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<Option<WarningKind>, 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)?;
let algo = nixhash.algo();
// 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()))?
}
},
},
);
// Peek at hash_str once more.
// If it was a SRI hash, but is not using the correct length, this means
// the padding was wrong. Emit a warning in that case.
let sri_prefix = format!("{}-", algo);
if let Some(rest) = hash_str.strip_prefix(&sri_prefix) {
if data_encoding::BASE64.encode_len(algo.digest_length()) != rest.len() {
return Ok(Some(WarningKind::SRIHashWrongPadding));
}
}
}
Ok(None)
}
#[builtins(state = "Rc<TvixStoreIO>")]
pub(crate) mod derivation_builtins {
use std::collections::BTreeMap;
use super::*;
use bstr::ByteSlice;
use nix_compat::store_path::hash_placeholder;
use tvix_eval::generators::Gen;
use tvix_eval::{NixContext, NixContextElement, NixString};
#[builtin("placeholder")]
async fn builtin_placeholder(co: GenCo, input: Value) -> Result<Value, ErrorKind> {
if input.is_catchable() {
return Ok(input);
}
let placeholder = hash_placeholder(
input
.to_str()
.context("looking at output name in builtins.placeholder")?
.to_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<TvixStoreIO>,
co: GenCo,
input: Value,
) -> Result<Value, ErrorKind> {
if input.is_catchable() {
return Ok(input);
}
let input = input.to_attrs()?;
let name = generators::request_force(&co, input.select_required("name")?.clone()).await;
if name.is_catchable() {
return Ok(name);
}
let name = name.to_str().context("determining derivation name")?;
if name.is_empty() {
return Err(ErrorKind::Abort("derivation has empty name".to_string()));
}
let name = name.to_str()?;
let mut drv = Derivation::default();
drv.outputs.insert("out".to_string(), Default::default());
let mut input_context = NixContext::new();
#[inline]
async fn strong_importing_coerce_to_string(
co: &GenCo,
val: Value,
) -> Result<NixString, CatchableErrorKind> {
let val = generators::request_force(co, val).await;
match generators::request_string_coerce(
co,
val,
CoercionKind {
strong: true,
import_paths: true,
},
)
.await
{
Err(cek) => Err(cek),
Ok(val_str) => Ok(val_str),
}
}
/// Inserts a key and value into the drv.environment BTreeMap, and fails if the
/// key did already exist before.
fn insert_env(
drv: &mut Derivation,
k: &str, /* TODO: non-utf8 env keys */
v: BString,
) -> Result<(), DerivationError> {
if drv.environment.insert(k.into(), v).is_some() {
return Err(DerivationError::DuplicateEnvVar(k.into()));
}
Ok(())
}
// 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,
};
// peek at the STRUCTURED_ATTRS argument.
// If it's set and true, provide a BTreeMap that gets populated while looking at the arguments.
// We need it to be a BTreeMap, so iteration order of keys is reproducible.
let mut structured_attrs: Option<BTreeMap<String, serde_json::Value>> =
match input.select(STRUCTURED_ATTRS) {
Some(b) => generators::request_force(&co, b.clone())
.await
.as_bool()?
.then_some(Default::default()),
None => None,
};
// Look at the arguments passed to builtins.derivationStrict.
// Some set special fields in the Derivation struct, some change
// behaviour of other functionality.
for (arg_name, arg_value) in input.clone().into_iter_sorted() {
let arg_name = arg_name.to_str()?;
// force the current value.
let value = generators::request_force(&co, arg_value).await;
// filter out nulls if ignore_nulls is set.
if ignore_nulls && matches!(value, Value::Null) {
continue;
}
match arg_name {
// Command line arguments to the builder.
// These are only set in drv.arguments.
"args" => {
for arg in value.to_list()? {
match strong_importing_coerce_to_string(&co, arg).await {
Err(cek) => return Ok(Value::from(cek)),
Ok(s) => {
input_context.mimic(&s);
drv.arguments.push(s.to_str()?.to_owned())
}
}
}
}
// If outputs is set, remove the original default `out` output,
// and replace it with the list of outputs.
"outputs" => {
let outputs = value
.to_list()
.context("looking at the `outputs` parameter of the derivation")?;
// Remove the original default `out` output.
drv.outputs.clear();
let mut output_names = vec![];
for output in outputs {
let output_name = generators::request_force(&co, output)
.await
.to_str()
.context("determining output name")?;
input_context.mimic(&output_name);
// Populate drv.outputs
if drv
.outputs
.insert(output_name.to_str()?.to_owned(), Default::default())
.is_some()
{
Err(DerivationError::DuplicateOutput(
output_name.to_str_lossy().into_owned(),
))?
}
output_names.push(output_name.to_str()?.to_owned());
}
// Add drv.environment[outputs] unconditionally.
insert_env(&mut drv, arg_name, output_names.join(" ").into())?;
// drv.environment[$output_name] is added after the loop,
// with whatever is in drv.outputs[$output_name].
}
// handle builder and system.
"builder" | "system" => {
match strong_importing_coerce_to_string(&co, value).await {
Err(cek) => return Ok(Value::from(cek)),
Ok(val_str) => {
input_context.mimic(&val_str);
if arg_name == "builder" {
drv.builder = val_str.to_str()?.to_owned();
} else {
drv.system = val_str.to_str()?.to_owned();
}
// Either populate drv.environment or structured_attrs.
if let Some(ref mut structured_attrs) = structured_attrs {
// No need to check for dups, we only iterate over every attribute name once
structured_attrs.insert(
arg_name.to_owned(),
val_str.to_str()?.to_owned().into(),
);
} else {
insert_env(&mut drv, arg_name, val_str.as_bytes().into())?;
}
}
}
}
// Don't add STRUCTURED_ATTRS if enabled.
STRUCTURED_ATTRS if structured_attrs.is_some() => continue,
// IGNORE_NULLS is always skipped, even if it's not set to true.
IGNORE_NULLS => continue,
// all other args.
_ => {
// In SA case, force and add to structured attrs.
// In non-SA case, coerce to string and add to env.
if let Some(ref mut structured_attrs) = structured_attrs {
let val = generators::request_force(&co, value).await;
if val.is_catchable() {
return Ok(val);
}
// TODO(raitobezarius): context for json values?
// input_context.mimic(&val);
let val_json = match val.into_json(&co).await? {
Ok(v) => v,
Err(cek) => return Ok(Value::from(cek)),
};
// No need to check for dups, we only iterate over every attribute name once
structured_attrs.insert(arg_name.to_owned(), val_json);
} else {
match strong_importing_coerce_to_string(&co, value).await {
Err(cek) => return Ok(Value::from(cek)),
Ok(val_str) => {
input_context.mimic(&val_str);
insert_env(&mut drv, arg_name, val_str.as_bytes().into())?;
}
}
}
}
}
}
// end of per-argument loop
// Configure fixed-output derivations if required.
{
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_importing_coerce_to_string(co, attr.clone()).await {
Err(cek) => return Ok(Err(cek)),
Ok(str) => return Ok(Ok(Some(str.to_str()?.to_owned()))),
}
}
Ok(Ok(None))
}
let output_hash = match select_string(&co, &input, "outputHash")
.await
.context("evaluating the `outputHash` parameter")?
{
Err(cek) => return Ok(Value::from(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::from(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::from(cek)),
Ok(s) => s,
};
if let Some(warning) =
handle_fixed_output(&mut drv, output_hash, output_hash_algo, output_hash_mode)?
{
emit_warning_kind(&co, warning).await;
}
}
// Each output name needs to exist in the environment, at this
// point initialised as an empty string, as the ATerm serialization of that is later
// used for the output path calculation (which will also update output
// paths post-calculation, both in drv.environment and drv.outputs)
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;
}
}
if let Some(structured_attrs) = structured_attrs {
// configure __json
drv.environment.insert(
"__json".to_string(),
BString::from(serde_json::to_string(&structured_attrs)?),
);
}
populate_inputs(&mut drv, input_context);
let mut known_paths = state.as_ref().known_paths.borrow_mut();
// 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_path| {
known_paths
.get_hash_derivation_modulo(&drv_path.to_owned())
.unwrap_or_else(|| panic!("{} not found", drv_path))
.to_owned()
});
// Mutate the Derivation struct and set output paths
drv.calculate_output_paths(name, &derivation_or_fod_hash_tmp)
.map_err(DerivationError::InvalidDerivation)?;
let drv_path = drv
.calculate_derivation_path(name)
.map_err(DerivationError::InvalidDerivation)?;
// TODO: avoid cloning
known_paths.add(drv_path.clone(), drv.clone());
let mut new_attrs: Vec<(String, NixString)> = drv
.outputs
.into_iter()
.map(|(name, output)| {
(
name.clone(),
(
output.path,
Some(
NixContextElement::Single {
name,
derivation: drv_path.to_absolute_path(),
}
.into(),
),
)
.into(),
)
})
.collect();
new_attrs.push((
"drvPath".to_string(),
(
drv_path.to_absolute_path(),
Some(NixContextElement::Derivation(drv_path.to_absolute_path()).into()),
)
.into(),
));
Ok(Value::Attrs(Box::new(NixAttrs::from_iter(
new_attrs.into_iter(),
))))
}
#[builtin("toFile")]
async fn builtin_to_file(co: GenCo, name: Value, content: Value) -> Result<Value, ErrorKind> {
if name.is_catchable() {
return Ok(name);
}
if content.is_catchable() {
return Ok(content);
}
let name = name
.to_str()
.context("evaluating the `name` parameter of builtins.toFile")?;
let content = content
.to_contextful_str()
.context("evaluating the `content` parameter of builtins.toFile")?;
if content.iter_derivation().count() > 0 || content.iter_single_outputs().count() > 0 {
return Err(ErrorKind::UnexpectedContext);
}
let path =
nix_compat::store_path::build_text_path(name.to_str()?, &content, content.iter_plain())
.map_err(|_e| {
nix_compat::derivation::DerivationError::InvalidOutputName(
name.to_str_lossy().into_owned(),
)
})
.map_err(DerivationError::InvalidDerivation)?
.to_absolute_path();
let context: NixContext = NixContextElement::Plain(path.clone()).into();
// TODO: actually persist the file in the store at that path ...
Ok(Value::from(NixString::new_context_from(context, path)))
}
}
