wasmer_wasix/runtime/package_loader/
load_package_tree.rs

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
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
use std::{
    collections::{BTreeMap, HashMap, HashSet},
    fmt::Debug,
    path::{Path, PathBuf},
    sync::Arc,
};

use anyhow::{Context, Error};
use futures::{future::BoxFuture, StreamExt, TryStreamExt};
use once_cell::sync::OnceCell;
use petgraph::visit::EdgeRef;
use virtual_fs::{FileSystem, OverlayFileSystem, UnionFileSystem, WebcVolumeFileSystem};
use wasmer_config::package::PackageId;
use webc::metadata::annotations::Atom as AtomAnnotation;
use webc::{Container, Volume};

use crate::{
    bin_factory::{BinaryPackage, BinaryPackageCommand},
    runtime::{
        package_loader::PackageLoader,
        resolver::{
            DependencyGraph, ItemLocation, PackageSummary, Resolution, ResolvedFileSystemMapping,
            ResolvedPackage,
        },
    },
};

use super::to_module_hash;

/// The maximum number of packages that will be loaded in parallel.
const MAX_PARALLEL_DOWNLOADS: usize = 32;

/// Given a fully resolved package, load it into memory for execution.
#[tracing::instrument(level = "debug", skip_all)]
pub async fn load_package_tree(
    root: &Container,
    loader: &dyn PackageLoader,
    resolution: &Resolution,
    root_is_local_dir: bool,
) -> Result<BinaryPackage, Error> {
    let mut containers = fetch_dependencies(loader, &resolution.package, &resolution.graph).await?;
    containers.insert(resolution.package.root_package.clone(), root.clone());
    let package_ids = containers.keys().cloned().collect();
    let fs = filesystem(&containers, &resolution.package, root_is_local_dir)?;

    let root = &resolution.package.root_package;
    let commands: Vec<BinaryPackageCommand> =
        commands(&resolution.package.commands, &containers, resolution)?;

    let file_system_memory_footprint = count_file_system(&fs, Path::new("/"));

    let loaded = BinaryPackage {
        id: root.clone(),
        package_ids,
        when_cached: crate::syscalls::platform_clock_time_get(
            wasmer_wasix_types::wasi::Snapshot0Clockid::Monotonic,
            1_000_000,
        )
        .ok()
        .map(|ts| ts as u128),
        hash: OnceCell::new(),
        entrypoint_cmd: resolution.package.entrypoint.clone(),
        webc_fs: Arc::new(fs),
        commands,
        uses: Vec::new(),
        file_system_memory_footprint,

        additional_host_mapped_directories: vec![],
    };

    Ok(loaded)
}

fn commands(
    commands: &BTreeMap<String, ItemLocation>,
    containers: &HashMap<PackageId, Container>,
    resolution: &Resolution,
) -> Result<Vec<BinaryPackageCommand>, Error> {
    let mut pkg_commands = Vec::new();

    for (
        name,
        ItemLocation {
            name: original_name,
            package,
        },
    ) in commands
    {
        let webc = &containers[package];
        let manifest = webc.manifest();
        let command_metadata = &manifest.commands[original_name];

        if let Some(cmd) =
            load_binary_command(package, name, command_metadata, containers, resolution)?
        {
            pkg_commands.push(cmd);
        }
    }

    Ok(pkg_commands)
}

/// Given a [`webc::metadata::Command`], figure out which atom it uses and load
/// that atom into a [`BinaryPackageCommand`].
#[tracing::instrument(skip_all, fields(%package_id, %command_name))]
fn load_binary_command(
    package_id: &PackageId,
    command_name: &str,
    cmd: &webc::metadata::Command,
    containers: &HashMap<PackageId, Container>,
    resolution: &Resolution,
) -> Result<Option<BinaryPackageCommand>, anyhow::Error> {
    let AtomAnnotation {
        name: atom_name,
        dependency,
        ..
    } = match atom_name_for_command(command_name, cmd)? {
        Some(name) => name,
        None => {
            tracing::warn!(
                cmd.name=command_name,
                cmd.runner=%cmd.runner,
                "Skipping unsupported command",
            );
            return Ok(None);
        }
    };

    let package = &containers[package_id];

    let (webc, resolved_package_id) = match dependency {
        Some(dep) => {
            let ix = resolution
                .graph
                .packages()
                .get(package_id)
                .copied()
                .unwrap();
            let graph = resolution.graph.graph();
            let edge_reference = graph
                .edges_directed(ix, petgraph::Direction::Outgoing)
                .find(|edge| edge.weight().alias == dep)
                .with_context(|| format!("Unable to find the \"{dep}\" dependency for the \"{command_name}\" command in \"{package_id}\""))?;

            let other_package = graph.node_weight(edge_reference.target()).unwrap();
            let id = &other_package.id;

            tracing::debug!(
                dependency=%dep,
                resolved_package_id=%id,
                "command atom resolution: resolved dependency",
            );
            (&containers[id], id)
        }
        None => (package, package_id),
    };

    let atom = webc.get_atom(&atom_name);

    if atom.is_none() && cmd.annotations.is_empty() {
        tracing::info!("applying legacy atom hack");
        return legacy_atom_hack(webc, command_name, cmd);
    }

    let hash = to_module_hash(webc.manifest().atom_signature(&atom_name)?);

    let atom = atom.with_context(|| {

        let available_atoms = webc.atoms().keys().map(|x| x.as_str()).collect::<Vec<_>>().join(",");

        tracing::warn!(
            %atom_name,
            %resolved_package_id,
            %available_atoms,
            "invalid command: could not find atom in package",
        );

        format!(
            "The '{command_name}' command uses the '{atom_name}' atom, but it isn't present in the package: {resolved_package_id})"
        )
    })?;

    let cmd = BinaryPackageCommand::new(command_name.to_string(), cmd.clone(), atom, hash);

    Ok(Some(cmd))
}

fn atom_name_for_command(
    command_name: &str,
    cmd: &webc::metadata::Command,
) -> Result<Option<AtomAnnotation>, anyhow::Error> {
    use webc::metadata::annotations::{WASI_RUNNER_URI, WCGI_RUNNER_URI};

    if let Some(atom) = cmd
        .atom()
        .context("Unable to deserialize atom annotations")?
    {
        return Ok(Some(atom));
    }

    if [WASI_RUNNER_URI, WCGI_RUNNER_URI]
        .iter()
        .any(|uri| cmd.runner.starts_with(uri))
    {
        // Note: We use the command name as the atom name as a special case
        // for known runner types because sometimes people will construct
        // a manifest by hand instead of using wapm2pirita.
        tracing::debug!(
            command = command_name,
            "No annotations specifying the atom name found. Falling back to the command name"
        );
        return Ok(Some(AtomAnnotation::new(command_name, None)));
    }

    Ok(None)
}

/// HACK: Some older packages like `sharrattj/bash` and `sharrattj/coreutils`
/// contain commands with no annotations. When this happens, you can just assume
/// it wants to use the first atom in the WEBC file.
///
/// That works because most of these packages only have a single atom (e.g. in
/// `sharrattj/coreutils` there are commands for `ls`, `pwd`, and so on, but
/// under the hood they all use the `coreutils` atom).
///
/// See <https://github.com/wasmerio/wasmer/commit/258903140680716da1431d92bced67d486865aeb>
/// for more.
fn legacy_atom_hack(
    webc: &Container,
    command_name: &str,
    metadata: &webc::metadata::Command,
) -> Result<Option<BinaryPackageCommand>, anyhow::Error> {
    let (name, atom) = webc
        .atoms()
        .into_iter()
        .next()
        .ok_or_else(|| anyhow::Error::msg("container does not have any atom"))?;

    tracing::debug!(
        command_name,
        atom.name = name.as_str(),
        atom.len = atom.len(),
        "(hack) The command metadata is malformed. Falling back to the first atom in the WEBC file",
    );

    let hash = to_module_hash(webc.manifest().atom_signature(&name)?);

    Ok(Some(BinaryPackageCommand::new(
        command_name.to_string(),
        metadata.clone(),
        atom,
        hash,
    )))
}

async fn fetch_dependencies(
    loader: &dyn PackageLoader,
    pkg: &ResolvedPackage,
    graph: &DependencyGraph,
) -> Result<HashMap<PackageId, Container>, Error> {
    let mut packages = HashSet::new();

    for loc in pkg.commands.values() {
        packages.insert(loc.package.clone());
    }

    for mapping in &pkg.filesystem {
        packages.insert(mapping.package.clone());
    }

    // We don't need to download the root package
    packages.remove(&pkg.root_package);

    let packages = packages.into_iter().filter_map(|id| {
        let crate::runtime::resolver::Node { pkg, dist, .. } = &graph[&id];
        let summary = PackageSummary {
            pkg: pkg.clone(),
            dist: dist.clone()?,
        };
        Some((id, summary))
    });
    let packages: HashMap<PackageId, Container> = futures::stream::iter(packages)
        .map(|(id, s)| async move {
            match loader.load(&s).await {
                Ok(webc) => Ok((id, webc)),
                Err(e) => Err(e),
            }
        })
        .buffer_unordered(MAX_PARALLEL_DOWNLOADS)
        .try_collect()
        .await?;

    Ok(packages)
}

/// How many bytes worth of files does a directory contain?
fn count_file_system(fs: &dyn FileSystem, path: &Path) -> u64 {
    let mut total = 0;

    let dir = match fs.read_dir(path) {
        Ok(d) => d,
        Err(_err) => {
            return 0;
        }
    };

    for entry in dir.flatten() {
        if let Ok(meta) = entry.metadata() {
            total += meta.len();
            if meta.is_dir() {
                total += count_file_system(fs, entry.path.as_path());
            }
        }
    }

    total
}

/// Given a set of [`ResolvedFileSystemMapping`]s and the [`Container`] for each
/// package in a dependency tree, construct the resulting filesystem.
fn filesystem(
    packages: &HashMap<PackageId, Container>,
    pkg: &ResolvedPackage,
    root_is_local_dir: bool,
) -> Result<Box<dyn FileSystem + Send + Sync>, Error> {
    if pkg.filesystem.is_empty() {
        return Ok(Box::new(OverlayFileSystem::<
            virtual_fs::EmptyFileSystem,
            Vec<WebcVolumeFileSystem>,
        >::new(
            virtual_fs::EmptyFileSystem::default(), vec![]
        )));
    }

    let mut found_v2 = false;
    let mut found_v3 = false;

    for ResolvedFileSystemMapping { package, .. } in &pkg.filesystem {
        let container = packages.get(package).with_context(|| {
            format!(
                "\"{}\" wants to use the \"{}\" package, but it isn't in the dependency tree",
                pkg.root_package, package,
            )
        })?;

        found_v2 |= container.version() == webc::Version::V2;
        found_v3 |= container.version() == webc::Version::V3;
    }

    if found_v3 && !found_v2 {
        filesystem_v3(packages, pkg, root_is_local_dir)
    } else {
        filesystem_v2(packages, pkg, root_is_local_dir)
    }
}

/// Build the filesystem for webc v3 packages.
fn filesystem_v3(
    packages: &HashMap<PackageId, Container>,
    pkg: &ResolvedPackage,
    root_is_local_dir: bool,
) -> Result<Box<dyn FileSystem + Send + Sync>, Error> {
    let mut volumes: HashMap<&PackageId, BTreeMap<String, Volume>> = HashMap::new();

    let mut mountings: Vec<_> = pkg.filesystem.iter().collect();
    mountings.sort_by_key(|m| std::cmp::Reverse(m.mount_path.as_path()));

    let union_fs = UnionFileSystem::new();

    for ResolvedFileSystemMapping {
        mount_path,
        volume_name,
        package,
        ..
    } in &pkg.filesystem
    {
        if *package == pkg.root_package && root_is_local_dir {
            continue;
        }

        // Note: We want to reuse existing Volume instances if we can. That way
        // we can keep the memory usage down. A webc::compat::Volume is
        // reference-counted, anyway.
        // looks like we need to insert it
        let container = packages.get(package).with_context(|| {
            format!(
                "\"{}\" wants to use the \"{}\" package, but it isn't in the dependency tree",
                pkg.root_package, package,
            )
        })?;
        let container_volumes = match volumes.entry(package) {
            std::collections::hash_map::Entry::Occupied(entry) => &*entry.into_mut(),
            std::collections::hash_map::Entry::Vacant(entry) => &*entry.insert(container.volumes()),
        };

        let volume = container_volumes.get(volume_name).with_context(|| {
            format!("The \"{package}\" package doesn't have a \"{volume_name}\" volume")
        })?;

        let webc_vol = WebcVolumeFileSystem::new(volume.clone());
        union_fs.mount(volume_name.clone(), mount_path, Box::new(webc_vol))?;
    }

    let fs = OverlayFileSystem::new(virtual_fs::EmptyFileSystem::default(), [union_fs]);

    Ok(Box::new(fs))
}

/// Build the filesystem for webc v2 packages.
///
// # Note to future readers
//
// Sooo... this code is a bit convoluted because we're constrained by the
// filesystem implementations we've got available.
//
// Ideally, we would create a WebcVolumeFileSystem for each volume we're
// using, then we'd have a single "union" filesystem which lets you mount
// filesystem objects under various paths and can deal with conflicts.
//
// The OverlayFileSystem lets us make files from multiple filesystem
// implementations available at the same time, however all of the
// filesystems will be mounted at "/", when the user wants to mount volumes
// at arbitrary locations.
//
// The TmpFileSystem *does* allow mounting at non-root paths, however it can't
// handle nested paths (e.g. mounting to "/lib" and "/lib/python3.10" - see
// <https://github.com/wasmerio/wasmer/issues/3678> for more) and you aren't
// allowed to mount to "/" because it's a special directory that already
// exists.
//
// As a result, we'll duct-tape things together and hope for the best 🤞
fn filesystem_v2(
    packages: &HashMap<PackageId, Container>,
    pkg: &ResolvedPackage,
    root_is_local_dir: bool,
) -> Result<Box<dyn FileSystem + Send + Sync>, Error> {
    let mut filesystems = Vec::new();
    let mut volumes: HashMap<&PackageId, BTreeMap<String, Volume>> = HashMap::new();

    let mut mountings: Vec<_> = pkg.filesystem.iter().collect();
    mountings.sort_by_key(|m| std::cmp::Reverse(m.mount_path.as_path()));

    for ResolvedFileSystemMapping {
        mount_path,
        volume_name,
        package,
        original_path,
    } in &pkg.filesystem
    {
        if *package == pkg.root_package && root_is_local_dir {
            continue;
        }

        // Note: We want to reuse existing Volume instances if we can. That way
        // we can keep the memory usage down. A webc::compat::Volume is
        // reference-counted, anyway.
        let container_volumes = match volumes.entry(package) {
            std::collections::hash_map::Entry::Occupied(entry) => &*entry.into_mut(),
            std::collections::hash_map::Entry::Vacant(entry) => {
                // looks like we need to insert it
                let container = packages.get(package)
                    .with_context(|| format!(
                        "\"{}\" wants to use the \"{}\" package, but it isn't in the dependency tree",
                        pkg.root_package,
                        package,
                    ))?;
                &*entry.insert(container.volumes())
            }
        };

        let volume = container_volumes.get(volume_name).with_context(|| {
            format!("The \"{package}\" package doesn't have a \"{volume_name}\" volume")
        })?;

        let mount_path = mount_path.clone();
        // Get a filesystem which will map "$mount_dir/some-path" to
        // "$original_path/some-path" on the original volume
        let fs = if let Some(original) = original_path {
            let original = PathBuf::from(original);

            MappedPathFileSystem::new(
                WebcVolumeFileSystem::new(volume.clone()),
                Box::new(move |path: &Path| {
                    let without_mount_dir = path
                        .strip_prefix(&mount_path)
                        .map_err(|_| virtual_fs::FsError::BaseNotDirectory)?;
                    Ok(original.join(without_mount_dir))
                }) as DynPathMapper,
            )
        } else {
            MappedPathFileSystem::new(
                WebcVolumeFileSystem::new(volume.clone()),
                Box::new(move |path: &Path| {
                    let without_mount_dir = path
                        .strip_prefix(&mount_path)
                        .map_err(|_| virtual_fs::FsError::BaseNotDirectory)?;
                    Ok(without_mount_dir.to_owned())
                }) as DynPathMapper,
            )
        };

        filesystems.push(fs);
    }

    let fs = OverlayFileSystem::new(virtual_fs::EmptyFileSystem::default(), filesystems);

    Ok(Box::new(fs))
}

type DynPathMapper = Box<dyn Fn(&Path) -> Result<PathBuf, virtual_fs::FsError> + Send + Sync>;

/// A [`FileSystem`] implementation that lets you map the [`Path`] to something
/// else.
#[derive(Clone, PartialEq)]
struct MappedPathFileSystem<F, M> {
    inner: F,
    map: M,
}

impl<F, M> MappedPathFileSystem<F, M>
where
    M: Fn(&Path) -> Result<PathBuf, virtual_fs::FsError> + Send + Sync + 'static,
{
    fn new(inner: F, map: M) -> Self {
        MappedPathFileSystem { inner, map }
    }

    fn path(&self, path: &Path) -> Result<PathBuf, virtual_fs::FsError> {
        let path = (self.map)(path)?;

        // Don't forget to make the path absolute again.
        Ok(Path::new("/").join(path))
    }
}

impl<M, F> FileSystem for MappedPathFileSystem<F, M>
where
    F: FileSystem,
    M: Fn(&Path) -> Result<PathBuf, virtual_fs::FsError> + Send + Sync + 'static,
{
    fn readlink(&self, path: &Path) -> virtual_fs::Result<PathBuf> {
        let path = self.path(path)?;
        self.inner.readlink(&path)
    }

    fn read_dir(&self, path: &Path) -> virtual_fs::Result<virtual_fs::ReadDir> {
        let path = self.path(path)?;
        self.inner.read_dir(&path)
    }

    fn create_dir(&self, path: &Path) -> virtual_fs::Result<()> {
        let path = self.path(path)?;
        self.inner.create_dir(&path)
    }

    fn remove_dir(&self, path: &Path) -> virtual_fs::Result<()> {
        let path = self.path(path)?;
        self.inner.remove_dir(&path)
    }

    fn rename<'a>(&'a self, from: &Path, to: &Path) -> BoxFuture<'a, virtual_fs::Result<()>> {
        let from = from.to_owned();
        let to = to.to_owned();
        Box::pin(async move {
            let from = self.path(&from)?;
            let to = self.path(&to)?;
            self.inner.rename(&from, &to).await
        })
    }

    fn metadata(&self, path: &Path) -> virtual_fs::Result<virtual_fs::Metadata> {
        let path = self.path(path)?;
        self.inner.metadata(&path)
    }

    fn symlink_metadata(&self, path: &Path) -> virtual_fs::Result<virtual_fs::Metadata> {
        let path = self.path(path)?;
        self.inner.symlink_metadata(&path)
    }

    fn remove_file(&self, path: &Path) -> virtual_fs::Result<()> {
        let path = self.path(path)?;
        self.inner.remove_file(&path)
    }

    fn new_open_options(&self) -> virtual_fs::OpenOptions {
        virtual_fs::OpenOptions::new(self)
    }

    fn mount(
        &self,
        name: String,
        path: &Path,
        fs: Box<dyn FileSystem + Send + Sync>,
    ) -> virtual_fs::Result<()> {
        let path = self.path(path)?;
        self.inner.mount(name, path.as_path(), fs)
    }
}

impl<F, M> virtual_fs::FileOpener for MappedPathFileSystem<F, M>
where
    F: FileSystem,
    M: Fn(&Path) -> Result<PathBuf, virtual_fs::FsError> + Send + Sync + 'static,
{
    fn open(
        &self,
        path: &Path,
        conf: &virtual_fs::OpenOptionsConfig,
    ) -> virtual_fs::Result<Box<dyn virtual_fs::VirtualFile + Send + Sync + 'static>> {
        let path = self.path(path)?;
        self.inner
            .new_open_options()
            .options(conf.clone())
            .open(path)
    }
}

impl<F, M> Debug for MappedPathFileSystem<F, M>
where
    F: Debug,
{
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("MappedPathFileSystem")
            .field("inner", &self.inner)
            .field("map", &std::any::type_name::<M>())
            .finish()
    }
}