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
//! Implements builtins used to import paths in the store.

use crate::tvix_store_io::TvixStoreIO;
use std::path::Path;
use tvix_castore::import::ingest_entries;
use tvix_castore::Node;
use tvix_eval::{
    builtin_macros::builtins,
    generators::{self, GenCo},
    ErrorKind, EvalIO, Value,
};

use std::rc::Rc;

async fn filtered_ingest(
    state: Rc<TvixStoreIO>,
    co: GenCo,
    path: &Path,
    filter: Option<&Value>,
) -> Result<Node, ErrorKind> {
    let mut entries: Vec<walkdir::DirEntry> = vec![];
    let mut it = walkdir::WalkDir::new(path)
        .follow_links(false)
        .follow_root_links(false)
        .contents_first(false)
        .into_iter();

    // Skip root node.
    entries.push(
        it.next()
            .ok_or_else(|| ErrorKind::IO {
                path: Some(path.to_path_buf()),
                error: std::io::Error::new(std::io::ErrorKind::NotFound, "No root node emitted")
                    .into(),
            })?
            .map_err(|err| ErrorKind::IO {
                path: Some(path.to_path_buf()),
                error: std::io::Error::from(err).into(),
            })?,
    );

    while let Some(entry) = it.next() {
        // Entry could be a NotFound, if the root path specified does not exist.
        let entry = entry.map_err(|err| ErrorKind::IO {
            path: err.path().map(|p| p.to_path_buf()),
            error: std::io::Error::from(err).into(),
        })?;

        // As per Nix documentation `:doc builtins.filterSource`.
        let file_type = if entry.file_type().is_dir() {
            "directory"
        } else if entry.file_type().is_file() {
            "regular"
        } else if entry.file_type().is_symlink() {
            "symlink"
        } else {
            "unknown"
        };

        let should_keep: bool = if let Some(filter) = filter {
            generators::request_force(
                &co,
                generators::request_call_with(
                    &co,
                    filter.clone(),
                    [
                        Value::String(entry.path().as_os_str().as_encoded_bytes().into()),
                        Value::String(file_type.into()),
                    ],
                )
                .await,
            )
            .await
            .as_bool()?
        } else {
            true
        };

        if !should_keep {
            if file_type == "directory" {
                it.skip_current_dir();
            }
            continue;
        }

        entries.push(entry);
    }

    let dir_entries = entries.into_iter().rev().map(Ok);

    state.tokio_handle.block_on(async {
        let entries = tvix_castore::import::fs::dir_entries_to_ingestion_stream::<'_, _, _, &[u8]>(
            &state.blob_service,
            dir_entries,
            path,
            None, // TODO re-scan
        );
        ingest_entries(&state.directory_service, entries)
            .await
            .map_err(|e| ErrorKind::IO {
                path: Some(path.to_path_buf()),
                error: Rc::new(std::io::Error::new(std::io::ErrorKind::Other, e)),
            })
    })
}

#[builtins(state = "Rc<TvixStoreIO>")]
mod import_builtins {
    use super::*;

    use crate::builtins::ImportError;
    use crate::tvix_store_io::TvixStoreIO;
    use bstr::ByteSlice;
    use nix_compat::nixhash::{CAHash, NixHash};
    use nix_compat::store_path::{build_ca_path, StorePathRef};
    use sha2::Digest;
    use std::rc::Rc;
    use tokio::io::AsyncWriteExt;
    use tvix_eval::builtins::coerce_value_to_path;
    use tvix_eval::generators::Gen;
    use tvix_eval::{generators::GenCo, ErrorKind, Value};
    use tvix_eval::{FileType, NixContextElement, NixString};
    use tvix_store::path_info::PathInfo;

    // This is a helper used by both builtins.path and builtins.filterSource.
    async fn import_helper(
        state: Rc<TvixStoreIO>,
        co: GenCo,
        path: std::path::PathBuf,
        name: Option<&Value>,
        filter: Option<&Value>,
        recursive_ingestion: bool,
        expected_sha256: Option<[u8; 32]>,
    ) -> Result<Value, ErrorKind> {
        let name: String = match name {
            Some(name) => generators::request_force(&co, name.clone())
                .await
                .to_str()?
                .as_bstr()
                .to_string(),
            None => tvix_store::import::path_to_name(&path)
                .expect("Failed to derive the default name out of the path")
                .to_string(),
        };
        // As a first step, we ingest the contents, and get back a root node,
        // and optionally the sha256 a flat file.
        let (root_node, ca) = match std::fs::metadata(&path)?.file_type().into() {
            // Check if the path points to a regular file.
            // If it does, the filter function is never executed, and we copy to the blobservice directly.
            // If recursive is false, we need to calculate the sha256 digest of the raw contents,
            // as that affects the output path calculation.
            FileType::Regular => {
                let mut file = state.open(&path)?;

                let mut flat_sha256 = (!recursive_ingestion).then(sha2::Sha256::new);
                let mut blob_size = 0;

                let mut blob_writer = state
                    .tokio_handle
                    .block_on(async { state.blob_service.open_write().await });

                // read piece by piece and write to blob_writer.
                // This is a bit manual due to EvalIO being sync, while everything else async.
                {
                    let mut buf = [0u8; 4096];

                    loop {
                        // read bytes into buffer, break out if EOF
                        let len = file.read(&mut buf)?;
                        if len == 0 {
                            break;
                        }
                        blob_size += len as u64;

                        let data = &buf[0..len];

                        // add to blobwriter
                        state
                            .tokio_handle
                            .block_on(async { blob_writer.write_all(data).await })?;

                        // update blob_sha256 if needed.
                        if let Some(h) = flat_sha256.as_mut() {
                            h.update(data)
                        }
                    }
                }

                // close the blob writer, construct the root node and the blob_sha256 (later used for output path calculation)
                (
                    Node::File {
                        digest: state
                            .tokio_handle
                            .block_on(async { blob_writer.close().await })?,
                        size: blob_size,
                        executable: false,
                    },
                    {
                        // If non-recursive ingestion is requested…
                        if let Some(flat_sha256) = flat_sha256 {
                            let actual_sha256 = flat_sha256.finalize().into();

                            // compare the recorded flat hash with an upfront one if provided.
                            if let Some(expected_sha256) = expected_sha256 {
                                if actual_sha256 != expected_sha256 {
                                    return Err(ImportError::HashMismatch(
                                        path,
                                        NixHash::Sha256(expected_sha256),
                                        NixHash::Sha256(actual_sha256),
                                    )
                                    .into());
                                }
                            }

                            Some(CAHash::Flat(NixHash::Sha256(actual_sha256)))
                        } else {
                            None
                        }
                    },
                )
            }

            FileType::Directory if !recursive_ingestion => {
                return Err(ImportError::FlatImportOfNonFile(path))?
            }

            // do the filtered ingest
            FileType::Directory => (
                filtered_ingest(state.clone(), co, path.as_ref(), filter).await?,
                None,
            ),
            FileType::Symlink => {
                // FUTUREWORK: Nix follows a symlink if it's at the root,
                // except if it's not resolve-able (NixOS/nix#7761).i
                return Err(tvix_eval::ErrorKind::IO {
                    path: Some(path),
                    error: Rc::new(std::io::Error::new(
                        std::io::ErrorKind::Unsupported,
                        "builtins.path pointing to a symlink is ill-defined.",
                    )),
                });
            }
            FileType::Unknown => {
                return Err(tvix_eval::ErrorKind::IO {
                    path: Some(path),
                    error: Rc::new(std::io::Error::new(
                        std::io::ErrorKind::Unsupported,
                        "unsupported file type",
                    )),
                })
            }
        };

        // Calculate the NAR sha256.
        let (nar_size, nar_sha256) = state
            .tokio_handle
            .block_on(async {
                state
                    .nar_calculation_service
                    .as_ref()
                    .calculate_nar(&root_node)
                    .await
            })
            .map_err(|e| tvix_eval::ErrorKind::TvixError(Rc::new(e)))?;

        // Calculate the CA hash for the recursive cases, this is only already
        // `Some(_)` for flat ingestion.
        let ca = match ca {
            None => {
                // If an upfront-expected NAR hash was specified, compare.
                if let Some(expected_nar_sha256) = expected_sha256 {
                    if expected_nar_sha256 != nar_sha256 {
                        return Err(ImportError::HashMismatch(
                            path,
                            NixHash::Sha256(expected_nar_sha256),
                            NixHash::Sha256(nar_sha256),
                        )
                        .into());
                    }
                }
                CAHash::Nar(NixHash::Sha256(nar_sha256))
            }
            Some(ca) => ca,
        };

        let store_path = build_ca_path(&name, &ca, Vec::<&str>::new(), false)
            .map_err(|e| tvix_eval::ErrorKind::TvixError(Rc::new(e)))?;

        let path_info = state
            .tokio_handle
            .block_on(async {
                state
                    .path_info_service
                    .as_ref()
                    .put(PathInfo {
                        store_path,
                        node: root_node,
                        // There's no reference scanning on path contents ingested like this.
                        references: vec![],
                        nar_size,
                        nar_sha256,
                        signatures: vec![],
                        deriver: None,
                        ca: Some(ca),
                    })
                    .await
            })
            .map_err(|e| tvix_eval::ErrorKind::IO {
                path: Some(path),
                error: Rc::new(e.into()),
            })?;

        // We need to attach context to the final output path.
        let outpath = path_info.store_path.to_absolute_path();

        Ok(
            NixString::new_context_from(NixContextElement::Plain(outpath.clone()).into(), outpath)
                .into(),
        )
    }

    #[builtin("path")]
    async fn builtin_path(
        state: Rc<TvixStoreIO>,
        co: GenCo,
        args: Value,
    ) -> Result<Value, ErrorKind> {
        let args = args.to_attrs()?;

        let path = match coerce_value_to_path(
            &co,
            generators::request_force(&co, args.select_required("path")?.clone()).await,
        )
        .await?
        {
            Ok(path) => path,
            Err(cek) => return Ok(cek.into()),
        };

        let filter = args.select("filter");

        // Construct a sha256 hasher, which is needed for flat ingestion.
        let recursive_ingestion = args
            .select("recursive")
            .map(|r| r.as_bool())
            .transpose()?
            .unwrap_or(true); // Yes, yes, Nix, by default, puts `recursive = true;`.

        let expected_sha256 = args
            .select("sha256")
            .map(|h| {
                h.to_str().and_then(|expected| {
                    match nix_compat::nixhash::from_str(expected.to_str()?, Some("sha256")) {
                        Ok(NixHash::Sha256(digest)) => Ok(digest),
                        Ok(_) => unreachable!(),
                        Err(e) => Err(ErrorKind::InvalidHash(e.to_string())),
                    }
                })
            })
            .transpose()?;

        import_helper(
            state,
            co,
            path,
            args.select("name"),
            filter,
            recursive_ingestion,
            expected_sha256,
        )
        .await
    }

    #[builtin("filterSource")]
    async fn builtin_filter_source(
        state: Rc<TvixStoreIO>,
        co: GenCo,
        #[lazy] filter: Value,
        path: Value,
    ) -> Result<Value, ErrorKind> {
        let path =
            match coerce_value_to_path(&co, generators::request_force(&co, path).await).await? {
                Ok(path) => path,
                Err(cek) => return Ok(cek.into()),
            };

        import_helper(state, co, path, None, Some(&filter), true, None).await
    }

    #[builtin("storePath")]
    async fn builtin_store_path(
        state: Rc<TvixStoreIO>,
        co: GenCo,
        path: Value,
    ) -> Result<Value, ErrorKind> {
        let p = match &path {
            Value::String(s) => Path::new(s.as_bytes().to_os_str()?),
            Value::Path(p) => p.as_path(),
            _ => {
                return Err(ErrorKind::TypeError {
                    expected: "string or path",
                    actual: path.type_of(),
                })
            }
        };

        // For this builtin, the path needs to start with an absolute store path.
        let (store_path, _sub_path) = StorePathRef::from_absolute_path_full(p)
            .map_err(|_e| ImportError::PathNotAbsoluteOrInvalid(p.to_path_buf()))?;

        if state.path_exists(p)? {
            Ok(Value::String(NixString::new_context_from(
                [NixContextElement::Plain(store_path.to_absolute_path())].into(),
                p.as_os_str().as_encoded_bytes(),
            )))
        } else {
            Err(ErrorKind::IO {
                path: Some(p.to_path_buf()),
                error: Rc::new(std::io::ErrorKind::NotFound.into()),
            })
        }
    }
}

pub use import_builtins::builtins as import_builtins;