about summary refs log tree commit diff
path: root/tvix/glue/src/builtins/derivation.rs
blob: b1487f4505e032f3d4a5ae1c660de7511a3e67e6 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
//! 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, ByteVec};
    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::Catchable(cek)),
                            Ok(s) => {
                                input_context.mimic(&s);
                                drv.arguments.push((**s).clone().into_string()?)
                            }
                        }
                    }
                }

                // 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).clone().into_string()?, Default::default())
                            .is_some()
                        {
                            Err(DerivationError::DuplicateOutput(
                                (**output_name).clone().into_string_lossy(),
                            ))?
                        }
                        output_names.push((**output_name).clone().into_string()?);
                    }

                    // 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::Catchable(cek)),
                        Ok(val_str) => {
                            input_context.mimic(&val_str);

                            if arg_name == "builder" {
                                drv.builder = (**val_str).clone().into_string()?;
                            } else {
                                drv.system = (**val_str).clone().into_string()?;
                            }

                            // 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).clone().into_string()?.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 matches!(val, Value::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::Catchable(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::Catchable(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).clone().into_string()?))),
                    }
                }

                Ok(Ok(None))
            }

            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,
            };

            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())
        });

        // 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)?;

        // recompute the hash derivation modulo and add to known_paths
        let derivation_or_fod_hash_final = drv.derivation_or_fod_hash(|drv_path| {
            known_paths.get_hash_derivation_modulo(&drv_path.to_owned())
        });

        known_paths.add_hash_derivation_modulo(drv_path.clone(), &derivation_or_fod_hash_final);

        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).clone().into_string_lossy(),
                    )
                })
                .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.into(),
        )))
    }
}