nix_compat/derivation/
parser.rs

1//! This module constructs a [Derivation] by parsing its [ATerm][]
2//! serialization.
3//!
4//! [ATerm]: http://program-transformation.org/Tools/ATermFormat.html
5
6use nom::Parser;
7use nom::bytes::streaming::tag;
8use nom::character::streaming::char as nomchar;
9use nom::combinator::{all_consuming, consumed, map_res};
10use nom::multi::{separated_list0, separated_list1};
11use nom::sequence::{delimited, preceded, separated_pair, terminated};
12use std::collections::{BTreeMap, BTreeSet, btree_map};
13use thiserror;
14
15use crate::derivation::output::OutputHash;
16use crate::derivation::parse_error::{ErrorKind, NomError, NomResult, into_nomerror};
17use crate::derivation::{Derivation, Output, OutputName, Outputs, write};
18use crate::store_path::{self, StorePath};
19use crate::{aterm, nixhash};
20
21#[derive(Debug, thiserror::Error)]
22pub enum Error<I> {
23    #[error("parsing error: {0}")]
24    Parser(#[from] NomError<I>),
25    #[error("premature EOF")]
26    Incomplete,
27    #[error("validation error: {0}")]
28    Validation(super::DerivationError),
29}
30
31/// Convenience conversion of borrowed Error to an owned counterpart.
32impl From<Error<&[u8]>> for Error<Vec<u8>> {
33    fn from(value: Error<&[u8]>) -> Self {
34        match value {
35            Error::Parser(nom_error) => Error::Parser(NomError {
36                input: nom_error.input.to_vec(),
37                code: nom_error.code,
38            }),
39            Error::Incomplete => Error::Incomplete,
40            Error::Validation(e) => Error::Validation(e),
41        }
42    }
43}
44
45pub(crate) fn parse(i: &[u8]) -> Result<Derivation, Error<&[u8]>> {
46    match all_consuming(parse_derivation).parse(i) {
47        Ok((rest, derivation)) => {
48            // this shouldn't happen, as all_consuming shouldn't return.
49            debug_assert!(rest.is_empty());
50
51            // invoke validate
52            derivation.validate().map_err(Error::Validation)?;
53
54            Ok(derivation)
55        }
56        Err(nom::Err::Incomplete(_)) => Err(Error::Incomplete),
57        Err(nom::Err::Error(e) | nom::Err::Failure(e)) => Err(e.into()),
58    }
59}
60
61/// This parses a derivation in streaming fashion.
62/// If the parse is successful, it returns the leftover bytes which were not used for the parsing.
63/// If the parse is unsuccessful, either it returns incomplete or an error with the input as
64/// leftover.
65#[allow(dead_code)]
66pub fn parse_streaming(i: &[u8]) -> (Result<Derivation, Error<&[u8]>>, &[u8]) {
67    match consumed(parse_derivation).parse(i) {
68        Ok((_, (rest, derivation))) => {
69            // invoke validate
70            if let Err(e) = derivation.validate().map_err(Error::Validation) {
71                return (Err(e), i);
72            }
73
74            (Ok(derivation), rest)
75        }
76        Err(nom::Err::Incomplete(_)) => (Err(Error::Incomplete), i),
77        Err(nom::Err::Error(e) | nom::Err::Failure(e)) => (Err(e.into()), i),
78    }
79}
80
81/// Parse one output in ATerm. This is 4 string fields inside parans:
82/// output name, output path, algo (and mode), digest.
83/// Returns the output name and [Output] struct.
84fn parse_output(i: &[u8]) -> NomResult<&[u8], (OutputName, Output)> {
85    delimited(
86        nomchar('('),
87        map_res(
88            |i| {
89                (
90                    terminated(aterm::parse_string_field, nomchar(',')),
91                    terminated(aterm::parse_string_field, nomchar(',')),
92                    terminated(aterm::parse_string_field, nomchar(',')),
93                    aterm::parse_bytes_field,
94                )
95                    .parse(i)
96                    .map_err(into_nomerror)
97            },
98            |(output_name_str, output_path_str, algo_and_mode, encoded_digest)| {
99                let output_name: OutputName = output_name_str.parse().map_err(|err| {
100                    nom::Err::Failure(NomError {
101                        input: i,
102                        code: ErrorKind::InvalidOutputName(err),
103                    })
104                })?;
105
106                // This can't be an empty string in ATerms written to disk.
107                // This being an empty string can only occur during output path calculation.
108                let output_path = string_to_store_path(i, &output_path_str)?;
109
110                Ok::<_, nom::Err<NomError<&[u8]>>>((
111                    output_name,
112                    Output {
113                        path: Some(output_path),
114                        output_hash: if algo_and_mode.is_empty() && encoded_digest.is_empty() {
115                            None
116                        } else {
117                            let digest =
118                                data_encoding::HEXLOWER
119                                    .decode(&encoded_digest)
120                                    .map_err(|err| {
121                                        nom::Err::Failure(NomError {
122                                            input: i,
123                                            code: ErrorKind::NixHashError(
124                                                // TODO: do we still need the outer error?
125                                                nixhash::Error::InvalidBase16Encoding(err),
126                                            ),
127                                        })
128                                    })?;
129
130                            Some(
131                                OutputHash::from_mode_algo_and_digest(&algo_and_mode, digest)
132                                    .map_err(|err| {
133                                        nom::Err::Failure(NomError {
134                                            input: i,
135                                            code: ErrorKind::NixHashError(err),
136                                        })
137                                    })?,
138                            )
139                        },
140                    },
141                ))
142            },
143        ),
144        nomchar(')'),
145    )
146    .parse(i)
147}
148
149/// Parse multiple outputs in ATerm. This is a list of things acccepted by
150/// parse_output, and takes care of turning the (String, Output) returned from
151/// it to a BTreeMap.
152/// We don't use parse_kv here, as it's dealing with 2-tuples, and these are
153/// 4-tuples.
154fn parse_outputs(i: &[u8]) -> NomResult<&[u8], Outputs> {
155    let res = delimited(
156        nomchar('['),
157        separated_list1(tag(","), parse_output),
158        nomchar(']'),
159    )
160    .parse(i);
161
162    match res {
163        Ok((rst, outputs_lst)) => {
164            let outputs = Outputs::try_from_iter(outputs_lst).map_err(|err| {
165                nom::Err::Failure(NomError {
166                    input: i,
167                    code: ErrorKind::InvalidOutputs(err),
168                })
169            })?;
170            Ok((rst, outputs))
171        }
172        // pass regular parse errors along
173        Err(e) => Err(e),
174    }
175}
176
177fn parse_input_derivations(
178    i: &[u8],
179) -> NomResult<&[u8], BTreeMap<StorePath, BTreeSet<OutputName>>> {
180    let (i, input_derivations_list) = parse_kv(aterm::parse_string_list)(i)?;
181
182    // This is a HashMap of drv paths to a list of output names.
183    let mut input_derivations: BTreeMap<StorePath, BTreeSet<_>> = BTreeMap::new();
184
185    for (input_derivation, output_names_strings) in input_derivations_list {
186        let mut output_names = BTreeSet::<OutputName>::new();
187        for output_name_string in output_names_strings.into_iter() {
188            let output_name = OutputName::try_from(output_name_string).map_err(|err| {
189                nom::Err::Failure(NomError {
190                    input: i,
191                    code: ErrorKind::InvalidOutputName(err),
192                })
193            })?;
194
195            if output_names.contains(&output_name) {
196                return Err(nom::Err::Failure(NomError {
197                    input: i,
198                    code: ErrorKind::DuplicateInputDerivationOutputName(
199                        output_name,
200                        input_derivation,
201                    ),
202                }));
203            }
204            output_names.insert(output_name);
205        }
206
207        let input_derivation = string_to_store_path(i, input_derivation.as_str())?;
208
209        input_derivations.insert(input_derivation, output_names);
210    }
211
212    Ok((i, input_derivations))
213}
214
215fn parse_input_sources(i: &[u8]) -> NomResult<&[u8], BTreeSet<StorePath>> {
216    let (i, input_sources_lst) = aterm::parse_string_list(i).map_err(into_nomerror)?;
217
218    let mut input_sources: BTreeSet<_> = BTreeSet::new();
219    for input_source in input_sources_lst.into_iter() {
220        let input_source = string_to_store_path(i, input_source.as_str())?;
221        if input_sources.contains(&input_source) {
222            return Err(nom::Err::Failure(NomError {
223                input: i,
224                code: ErrorKind::DuplicateInputSource(input_source.to_owned()),
225            }));
226        } else {
227            input_sources.insert(input_source);
228        }
229    }
230
231    Ok((i, input_sources))
232}
233
234fn string_to_store_path<'i>(
235    i: &'i [u8],
236    path_str: &str,
237) -> Result<StorePath, nom::Err<NomError<&'i [u8]>>> {
238    let path = StorePath::from_absolute_path(path_str.as_bytes()).map_err(
239        |e: store_path::ParseStorePathError| {
240            nom::Err::Failure(NomError {
241                input: i,
242                code: e.into(),
243            })
244        },
245    )?;
246
247    #[cfg(debug_assertions)]
248    assert_eq!(path_str, path.to_absolute_path());
249
250    Ok(path)
251}
252
253pub fn parse_derivation(i: &[u8]) -> NomResult<&[u8], Derivation> {
254    use nom::Parser;
255    preceded(
256        tag(write::DERIVATION_PREFIX),
257        delimited(
258            // inside parens
259            nomchar('('),
260            // tuple requires all errors to be of the same type, so we need to be a
261            // bit verbose here wrapping generic IResult into [NomATermResult].
262            (
263                // parse outputs
264                terminated(parse_outputs, nomchar(',')),
265                // // parse input derivations
266                terminated(parse_input_derivations, nomchar(',')),
267                // // parse input sources
268                terminated(parse_input_sources, nomchar(',')),
269                // // parse system
270                |i| {
271                    terminated(aterm::parse_string_field, nomchar(','))
272                        .parse(i)
273                        .map_err(into_nomerror)
274                },
275                // // parse builder
276                |i| {
277                    terminated(aterm::parse_string_field, nomchar(','))
278                        .parse(i)
279                        .map_err(into_nomerror)
280                },
281                // // parse arguments
282                |i| {
283                    terminated(aterm::parse_string_list, nomchar(','))
284                        .parse(i)
285                        .map_err(into_nomerror)
286                },
287                // parse environment
288                parse_kv(aterm::parse_bytes_field),
289            ),
290            nomchar(')'),
291        )
292        .map(
293            |(
294                outputs,
295                input_derivations,
296                input_sources,
297                system,
298                builder,
299                arguments,
300                environment,
301            )| {
302                Derivation {
303                    arguments,
304                    builder,
305                    environment,
306                    input_derivations,
307                    input_sources,
308                    outputs,
309                    system,
310                }
311            },
312        ),
313    )
314    .parse(i)
315}
316
317/// Parse a list of key/value pairs into a BTreeMap.
318/// The parser for the values can be passed in.
319/// In terms of ATerm, this is just a 2-tuple,
320/// but we have the additional restriction that the first element needs to be
321/// unique across all tuples.
322pub(crate) fn parse_kv<'a, V, VF>(
323    vf: VF,
324) -> impl FnMut(&'a [u8]) -> NomResult<&'a [u8], BTreeMap<String, V>> + 'static
325where
326    VF: FnMut(&'a [u8]) -> nom::IResult<&'a [u8], V, nom::error::Error<&'a [u8]>> + Clone + 'static,
327{
328    move |i|
329    // inside brackets
330    delimited(
331        nomchar('['),
332        |ii| {
333            let res = separated_list0(
334                nomchar(','),
335                // inside parens
336                delimited(
337                    nomchar('('),
338                    separated_pair(
339                        aterm::parse_string_field,
340                        nomchar(','),
341                        vf.clone(),
342                    ),
343                    nomchar(')'),
344                ),
345            ).parse(ii).map_err(into_nomerror);
346
347            match res {
348                Ok((rest, pairs)) => {
349                    let mut kvs: BTreeMap<String, V> = BTreeMap::new();
350                    for (k, v) in pairs.into_iter() {
351                        // collect the 2-tuple to a BTreeMap,
352                        // and fail if the key was already seen before.
353                        match kvs.entry(k) {
354                            btree_map::Entry::Vacant(e) => { e.insert(v); },
355                            btree_map::Entry::Occupied(e) => {
356                                return Err(nom::Err::Failure(NomError {
357                                    input: i,
358                                    code: ErrorKind::DuplicateMapKey(e.key().clone()),
359                                }));
360                            }
361                        }
362                    }
363                    Ok((rest, kvs))
364                }
365                Err(e) => Err(e),
366            }
367        },
368        nomchar(']'),
369    ).parse(i)
370}
371
372#[cfg(test)]
373mod tests {
374    use super::OutputHash;
375    use crate::derivation::{Output, OutputHashMode, OutputName, Outputs};
376    use crate::store_path::StorePathRef;
377    use crate::{
378        derivation::{NixHash, parse_error::ErrorKind},
379        store_path::StorePath,
380    };
381    use std::collections::{BTreeMap, BTreeSet};
382    use std::sync::LazyLock;
383
384    use bstr::{BString, ByteSlice};
385    use hex_literal::hex;
386    use rstest::rstest;
387
388    static EXP_MULTI_OUTPUTS: LazyLock<Outputs> = LazyLock::new(|| {
389        let mut b = BTreeMap::new();
390        b.insert(
391            "lib".parse().expect("valid OutputName"),
392            Output {
393                path: Some(
394                    StorePath::from_bytes(b"2vixb94v0hy2xc6p7mbnxxcyc095yyia-has-multi-out-lib")
395                        .unwrap(),
396                ),
397                output_hash: None,
398            },
399        );
400        b.insert(
401            "out".parse().expect("valid OutputName"),
402            Output {
403                path: Some(
404                    StorePath::from_bytes(
405                        b"55lwldka5nyxa08wnvlizyqw02ihy8ic-has-multi-out".as_bytes(),
406                    )
407                    .unwrap(),
408                ),
409                output_hash: None,
410            },
411        );
412        b.try_into().unwrap()
413    });
414
415    static EXP_AB_MAP: LazyLock<BTreeMap<String, BString>> = LazyLock::new(|| {
416        let mut b = BTreeMap::new();
417        b.insert("a".to_string(), b"1".into());
418        b.insert("b".to_string(), b"2".into());
419        b
420    });
421
422    static EXP_INPUT_DERIVATIONS_SIMPLE: LazyLock<BTreeMap<StorePath, BTreeSet<OutputName>>> =
423        LazyLock::new(|| {
424            let mut b = BTreeMap::new();
425            b.insert(
426                StorePath::from_bytes(b"8bjm87p310sb7r2r0sg4xrynlvg86j8k-hello-2.12.1.tar.gz.drv")
427                    .unwrap(),
428                BTreeSet::from([OutputName::out()]),
429            );
430            b.insert(
431                StorePath::from_bytes(b"p3jc8aw45dza6h52v81j7lk69khckmcj-bash-5.2-p15.drv")
432                    .unwrap(),
433                BTreeSet::from([OutputName::out(), "lib".parse().expect("valid OutputName")]),
434            );
435            b
436        });
437
438    static EXP_INPUT_DERIVATIONS_SIMPLE_ATERM: LazyLock<String> = LazyLock::new(|| {
439        format!(
440            "[(\"{0}\",[\"out\"]),(\"{1}\",[\"out\",\"lib\"])]",
441            "/nix/store/8bjm87p310sb7r2r0sg4xrynlvg86j8k-hello-2.12.1.tar.gz.drv",
442            "/nix/store/p3jc8aw45dza6h52v81j7lk69khckmcj-bash-5.2-p15.drv"
443        )
444    });
445
446    static EXP_INPUT_SOURCES_SIMPLE: LazyLock<BTreeSet<String>> = LazyLock::new(|| {
447        let mut b = BTreeSet::new();
448        b.insert("/nix/store/55lwldka5nyxa08wnvlizyqw02ihy8ic-has-multi-out".to_string());
449        b.insert("/nix/store/2vixb94v0hy2xc6p7mbnxxcyc095yyia-has-multi-out-lib".to_string());
450        b
451    });
452
453    /// Ensure parsing KVs works
454    #[rstest]
455    #[case::empty(b"[]", &BTreeMap::new(), b"")]
456    #[case::simple(b"[(\"a\",\"1\"),(\"b\",\"2\")]", &EXP_AB_MAP, b"")]
457    fn parse_kv(
458        #[case] input: &'static [u8],
459        #[case] expected: &BTreeMap<String, BString>,
460        #[case] exp_rest: &[u8],
461    ) {
462        let (rest, parsed) =
463            super::parse_kv(crate::aterm::parse_bytes_field)(input).expect("must parse");
464        assert_eq!(exp_rest, rest, "expected remainder");
465        assert_eq!(*expected, parsed);
466    }
467
468    #[rstest]
469    #[case::incomplete_empty(b"[")]
470    #[case::incomplete_simple(b"[(\"a\",\"1\")")]
471    #[case::incomplete_complicated_escape(b"[(\"a")]
472    #[case::incomplete_complicated_sep(b"[(\"a\",")]
473    #[case::incomplete_complicated_multi_escape(b"[(\"a\",\"")]
474    #[case::incomplete_complicated_multi_outer_sep(b"[(\"a\",\"b\"),")]
475    fn parse_kv_incomplete(#[case] input: &'static [u8]) {
476        assert!(matches!(
477            super::parse_kv(crate::aterm::parse_bytes_field)(input),
478            Err(nom::Err::Incomplete(_))
479        ));
480    }
481
482    /// Ensures the kv parser complains about duplicate map keys
483    #[test]
484    fn parse_kv_fail_dup_keys() {
485        let input: &'static [u8] = b"[(\"a\",\"1\"),(\"a\",\"2\")]";
486        let e = super::parse_kv(crate::aterm::parse_bytes_field)(input).expect_err("must fail");
487
488        match e {
489            nom::Err::Failure(e) => {
490                assert_eq!(ErrorKind::DuplicateMapKey("a".to_string()), e.code);
491            }
492            _ => panic!("unexpected error"),
493        }
494    }
495
496    /// Ensure parsing input derivations works.
497    #[rstest]
498    #[case::empty(b"[]", &BTreeMap::new())]
499    #[case::simple(EXP_INPUT_DERIVATIONS_SIMPLE_ATERM.as_bytes(), &EXP_INPUT_DERIVATIONS_SIMPLE)]
500    fn parse_input_derivations(
501        #[case] input: &'static [u8],
502        #[case] expected: &BTreeMap<StorePath, BTreeSet<OutputName>>,
503    ) {
504        let (rest, parsed) = super::parse_input_derivations(input).expect("must parse");
505
506        assert_eq!(expected, &parsed, "parsed mismatch");
507        assert!(rest.is_empty(), "rest must be empty");
508    }
509
510    /// Ensures the input derivation parser complains about duplicate output names
511    #[test]
512    fn parse_input_derivations_fail_dup_output_names() {
513        let input_str = format!(
514            "[(\"{0}\",[\"out\"]),(\"{1}\",[\"out\",\"out\"])]",
515            "/nix/store/8bjm87p310sb7r2r0sg4xrynlvg86j8k-hello-2.12.1.tar.gz.drv",
516            "/nix/store/p3jc8aw45dza6h52v81j7lk69khckmcj-bash-5.2-p15.drv"
517        );
518        let e = super::parse_input_derivations(input_str.as_bytes()).expect_err("must fail");
519
520        match e {
521            nom::Err::Failure(e) => {
522                assert_eq!(
523                    ErrorKind::DuplicateInputDerivationOutputName(
524                        "out".parse().expect("Valid OutputName"),
525                        "/nix/store/p3jc8aw45dza6h52v81j7lk69khckmcj-bash-5.2-p15.drv".to_string(),
526                    ),
527                    e.code
528                );
529            }
530            _ => panic!("unexpected error"),
531        }
532    }
533
534    /// Ensure parsing input sources works
535    #[rstest]
536    #[case::empty(b"[]", &BTreeSet::new())]
537    #[case::simple(b"[\"/nix/store/55lwldka5nyxa08wnvlizyqw02ihy8ic-has-multi-out\",\"/nix/store/2vixb94v0hy2xc6p7mbnxxcyc095yyia-has-multi-out-lib\"]", &EXP_INPUT_SOURCES_SIMPLE)]
538    fn parse_input_sources(#[case] input: &'static [u8], #[case] expected: &BTreeSet<String>) {
539        let (rest, parsed) = super::parse_input_sources(input).expect("must parse");
540
541        assert_eq!(
542            expected,
543            &parsed
544                .iter()
545                .map(StorePath::to_absolute_path)
546                .collect::<BTreeSet<_>>(),
547            "parsed mismatch"
548        );
549        assert!(rest.is_empty(), "rest must be empty");
550    }
551
552    /// Ensures the input sources parser complains about duplicate input sources
553    #[test]
554    fn parse_input_sources_fail_dup_keys() {
555        let input: &'static [u8] = b"[\"/nix/store/55lwldka5nyxa08wnvlizyqw02ihy8ic-foo\",\"/nix/store/55lwldka5nyxa08wnvlizyqw02ihy8ic-foo\"]";
556        let e = super::parse_input_sources(input).expect_err("must fail");
557
558        match e {
559            nom::Err::Failure(e) => {
560                assert_eq!(
561                    ErrorKind::DuplicateInputSource(
562                        StorePathRef::from_absolute_path(
563                            "/nix/store/55lwldka5nyxa08wnvlizyqw02ihy8ic-foo".as_bytes()
564                        )
565                        .unwrap()
566                        .to_owned()
567                    ),
568                    e.code
569                );
570            }
571            _ => panic!("unexpected error"),
572        }
573    }
574
575    #[rstest]
576    #[case::simple(
577        br#"("out","/nix/store/5vyvcwah9l9kf07d52rcgdk70g2f4y13-foo","","")"#,
578        (OutputName::out(), Output {
579            path: Some(
580                StorePathRef::from_absolute_path("/nix/store/5vyvcwah9l9kf07d52rcgdk70g2f4y13-foo".as_bytes()).unwrap().to_owned()),
581            output_hash: None
582        })
583    )]
584    #[case::fod(
585        br#"("out","/nix/store/4q0pg5zpfmznxscq3avycvf9xdvx50n3-bar","r:sha256","08813cbee9903c62be4c5027726a418a300da4500b2d369d3af9286f4815ceba")"#,
586        (OutputName::out(), Output {
587            path: Some(
588                StorePathRef::from_absolute_path(
589                "/nix/store/4q0pg5zpfmznxscq3avycvf9xdvx50n3-bar".as_bytes()).unwrap().to_owned()),
590            output_hash: Some(OutputHash{
591                mode: OutputHashMode::Recursive,
592                hash: NixHash::Sha256(hex!("08813cbee9903c62be4c5027726a418a300da4500b2d369d3af9286f4815ceba")),
593            }),
594        })
595    )]
596    fn parse_output(#[case] input: &[u8], #[case] expected: (OutputName, Output)) {
597        let (rest, parsed) = super::parse_output(input).expect("must parse");
598        assert!(rest.is_empty());
599        assert_eq!(expected, parsed);
600    }
601
602    #[rstest]
603    #[case::multi_out(
604        br#"[("lib","/nix/store/2vixb94v0hy2xc6p7mbnxxcyc095yyia-has-multi-out-lib","",""),("out","/nix/store/55lwldka5nyxa08wnvlizyqw02ihy8ic-has-multi-out","","")]"#,
605        &EXP_MULTI_OUTPUTS
606    )]
607    fn parse_outputs(#[case] input: &[u8], #[case] expected: &Outputs) {
608        let (rest, parsed) = super::parse_outputs(input).expect("must parse");
609        assert!(rest.is_empty());
610        assert_eq!(*expected, parsed);
611    }
612}
nix_compat/derivation/parser.rs

nix_compat/derivation/
parser.rs
