Merge branch 'denoland:main' into main

1 files changed, 661 insertions, 0 deletions

diff --git a/cli/standalone/serialization.rs b/cli/standalone/serialization.rs
new file mode 100644
index 000000000..a5eb649bf
--- /dev/null
+++ b/cli/standalone/serialization.rs
@@ -0,0 +1,661 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+use std::borrow::Cow;
+use std::collections::BTreeMap;
+use std::collections::HashMap;
+use std::io::Write;
+
+use deno_ast::MediaType;
+use deno_core::anyhow::bail;
+use deno_core::anyhow::Context;
+use deno_core::error::AnyError;
+use deno_core::serde_json;
+use deno_core::url::Url;
+use deno_core::FastString;
+use deno_core::ModuleSourceCode;
+use deno_core::ModuleType;
+use deno_npm::resolution::SerializedNpmResolutionSnapshot;
+use deno_npm::resolution::SerializedNpmResolutionSnapshotPackage;
+use deno_npm::resolution::ValidSerializedNpmResolutionSnapshot;
+use deno_npm::NpmPackageId;
+use deno_semver::package::PackageReq;
+
+use crate::standalone::virtual_fs::VirtualDirectory;
+
+use super::binary::Metadata;
+use super::virtual_fs::VfsBuilder;
+
+const MAGIC_BYTES: &[u8; 8] = b"d3n0l4nd";
+
+/// Binary format:
+/// * d3n0l4nd
+/// * <metadata_len><metadata>
+/// * <npm_snapshot_len><npm_snapshot>
+/// * <remote_modules_len><remote_modules>
+/// * <vfs_headers_len><vfs_headers>
+/// * <vfs_file_data_len><vfs_file_data>
+/// * d3n0l4nd
+pub fn serialize_binary_data_section(
+  metadata: &Metadata,
+  npm_snapshot: Option<SerializedNpmResolutionSnapshot>,
+  remote_modules: &RemoteModulesStoreBuilder,
+  vfs: VfsBuilder,
+) -> Result<Vec<u8>, AnyError> {
+  fn write_bytes_with_len(bytes: &mut Vec<u8>, data: &[u8]) {
+    bytes.extend_from_slice(&(data.len() as u64).to_le_bytes());
+    bytes.extend_from_slice(data);
+  }
+
+  let mut bytes = Vec::new();
+  bytes.extend_from_slice(MAGIC_BYTES);
+
+  // 1. Metadata
+  {
+    let metadata = serde_json::to_string(metadata)?;
+    write_bytes_with_len(&mut bytes, metadata.as_bytes());
+  }
+  // 2. Npm snapshot
+  {
+    let npm_snapshot =
+      npm_snapshot.map(serialize_npm_snapshot).unwrap_or_default();
+    write_bytes_with_len(&mut bytes, &npm_snapshot);
+  }
+  // 3. Remote modules
+  {
+    let update_index = bytes.len();
+    bytes.extend_from_slice(&(0_u64).to_le_bytes());
+    let start_index = bytes.len();
+    remote_modules.write(&mut bytes)?;
+    let length = bytes.len() - start_index;
+    let length_bytes = (length as u64).to_le_bytes();
+    bytes[update_index..update_index + length_bytes.len()]
+      .copy_from_slice(&length_bytes);
+  }
+  // 4. VFS
+  {
+    let (vfs, vfs_files) = vfs.into_dir_and_files();
+    let vfs = serde_json::to_string(&vfs)?;
+    write_bytes_with_len(&mut bytes, vfs.as_bytes());
+    let vfs_bytes_len = vfs_files.iter().map(|f| f.len() as u64).sum::<u64>();
+    bytes.extend_from_slice(&vfs_bytes_len.to_le_bytes());
+    for file in &vfs_files {
+      bytes.extend_from_slice(file);
+    }
+  }
+
+  // write the magic bytes at the end so we can use it
+  // to make sure we've deserialized correctly
+  bytes.extend_from_slice(MAGIC_BYTES);
+
+  Ok(bytes)
+}
+
+pub struct DeserializedDataSection {
+  pub metadata: Metadata,
+  pub npm_snapshot: Option<ValidSerializedNpmResolutionSnapshot>,
+  pub remote_modules: RemoteModulesStore,
+  pub vfs_dir: VirtualDirectory,
+  pub vfs_files_data: &'static [u8],
+}
+
+pub fn deserialize_binary_data_section(
+  data: &'static [u8],
+) -> Result<Option<DeserializedDataSection>, AnyError> {
+  fn read_bytes_with_len(input: &[u8]) -> Result<(&[u8], &[u8]), AnyError> {
+    let (input, len) = read_u64(input)?;
+    let (input, data) = read_bytes(input, len as usize)?;
+    Ok((input, data))
+  }
+
+  fn read_magic_bytes(input: &[u8]) -> Result<(&[u8], bool), AnyError> {
+    if input.len() < MAGIC_BYTES.len() {
+      bail!("Unexpected end of data. Could not find magic bytes.");
+    }
+    let (magic_bytes, input) = input.split_at(MAGIC_BYTES.len());
+    if magic_bytes != MAGIC_BYTES {
+      return Ok((input, false));
+    }
+    Ok((input, true))
+  }
+
+  let (input, found) = read_magic_bytes(data)?;
+  if !found {
+    return Ok(None);
+  }
+
+  // 1. Metadata
+  let (input, data) = read_bytes_with_len(input).context("reading metadata")?;
+  let metadata: Metadata =
+    serde_json::from_slice(data).context("deserializing metadata")?;
+  // 2. Npm snapshot
+  let (input, data) =
+    read_bytes_with_len(input).context("reading npm snapshot")?;
+  let npm_snapshot = if data.is_empty() {
+    None
+  } else {
+    Some(deserialize_npm_snapshot(data).context("deserializing npm snapshot")?)
+  };
+  // 3. Remote modules
+  let (input, data) =
+    read_bytes_with_len(input).context("reading remote modules data")?;
+  let remote_modules =
+    RemoteModulesStore::build(data).context("deserializing remote modules")?;
+  // 4. VFS
+  let (input, data) = read_bytes_with_len(input).context("vfs")?;
+  let vfs_dir: VirtualDirectory =
+    serde_json::from_slice(data).context("deserializing vfs data")?;
+  let (input, vfs_files_data) =
+    read_bytes_with_len(input).context("reading vfs files data")?;
+
+  // finally ensure we read the magic bytes at the end
+  let (_input, found) = read_magic_bytes(input)?;
+  if !found {
+    bail!("Could not find magic bytes at the end of the data.");
+  }
+
+  Ok(Some(DeserializedDataSection {
+    metadata,
+    npm_snapshot,
+    remote_modules,
+    vfs_dir,
+    vfs_files_data,
+  }))
+}
+
+#[derive(Default)]
+pub struct RemoteModulesStoreBuilder {
+  specifiers: Vec<(String, u64)>,
+  data: Vec<(MediaType, Vec<u8>)>,
+  data_byte_len: u64,
+  redirects: Vec<(String, String)>,
+  redirects_len: u64,
+}
+
+impl RemoteModulesStoreBuilder {
+  pub fn add(&mut self, specifier: &Url, media_type: MediaType, data: Vec<u8>) {
+    log::debug!("Adding '{}' ({})", specifier, media_type);
+    let specifier = specifier.to_string();
+    self.specifiers.push((specifier, self.data_byte_len));
+    self.data_byte_len += 1 + 8 + data.len() as u64; // media type (1 byte), data length (8 bytes), data
+    self.data.push((media_type, data));
+  }
+
+  pub fn add_redirects(&mut self, redirects: &BTreeMap<Url, Url>) {
+    self.redirects.reserve(redirects.len());
+    for (from, to) in redirects {
+      log::debug!("Adding redirect '{}' -> '{}'", from, to);
+      let from = from.to_string();
+      let to = to.to_string();
+      self.redirects_len += (4 + from.len() + 4 + to.len()) as u64;
+      self.redirects.push((from, to));
+    }
+  }
+
+  fn write(&self, writer: &mut dyn Write) -> Result<(), AnyError> {
+    writer.write_all(&(self.specifiers.len() as u32).to_le_bytes())?;
+    writer.write_all(&(self.redirects.len() as u32).to_le_bytes())?;
+    for (specifier, offset) in &self.specifiers {
+      writer.write_all(&(specifier.len() as u32).to_le_bytes())?;
+      writer.write_all(specifier.as_bytes())?;
+      writer.write_all(&offset.to_le_bytes())?;
+    }
+    for (from, to) in &self.redirects {
+      writer.write_all(&(from.len() as u32).to_le_bytes())?;
+      writer.write_all(from.as_bytes())?;
+      writer.write_all(&(to.len() as u32).to_le_bytes())?;
+      writer.write_all(to.as_bytes())?;
+    }
+    for (media_type, data) in &self.data {
+      writer.write_all(&[serialize_media_type(*media_type)])?;
+      writer.write_all(&(data.len() as u64).to_le_bytes())?;
+      writer.write_all(data)?;
+    }
+    Ok(())
+  }
+}
+
+pub enum DenoCompileModuleSource {
+  String(&'static str),
+  Bytes(Cow<'static, [u8]>),
+}
+
+impl DenoCompileModuleSource {
+  pub fn into_for_v8(self) -> ModuleSourceCode {
+    fn into_bytes(data: Cow<'static, [u8]>) -> ModuleSourceCode {
+      ModuleSourceCode::Bytes(match data {
+        Cow::Borrowed(d) => d.into(),
+        Cow::Owned(d) => d.into_boxed_slice().into(),
+      })
+    }
+
+    match self {
+      // todo(https://github.com/denoland/deno_core/pull/943): store whether
+      // the string is ascii or not ahead of time so we can avoid the is_ascii()
+      // check in FastString::from_static
+      Self::String(s) => ModuleSourceCode::String(FastString::from_static(s)),
+      Self::Bytes(b) => into_bytes(b),
+    }
+  }
+}
+
+pub struct DenoCompileModuleData<'a> {
+  pub specifier: &'a Url,
+  pub media_type: MediaType,
+  pub data: Cow<'static, [u8]>,
+}
+
+impl<'a> DenoCompileModuleData<'a> {
+  pub fn into_parts(self) -> (&'a Url, ModuleType, DenoCompileModuleSource) {
+    fn into_string_unsafe(data: Cow<'static, [u8]>) -> DenoCompileModuleSource {
+      match data {
+        Cow::Borrowed(d) => DenoCompileModuleSource::String(
+          // SAFETY: we know this is a valid utf8 string
+          unsafe { std::str::from_utf8_unchecked(d) },
+        ),
+        Cow::Owned(d) => DenoCompileModuleSource::Bytes(Cow::Owned(d)),
+      }
+    }
+
+    let (media_type, source) = match self.media_type {
+      MediaType::JavaScript
+      | MediaType::Jsx
+      | MediaType::Mjs
+      | MediaType::Cjs
+      | MediaType::TypeScript
+      | MediaType::Mts
+      | MediaType::Cts
+      | MediaType::Dts
+      | MediaType::Dmts
+      | MediaType::Dcts
+      | MediaType::Tsx => {
+        (ModuleType::JavaScript, into_string_unsafe(self.data))
+      }
+      MediaType::Json => (ModuleType::Json, into_string_unsafe(self.data)),
+      MediaType::Wasm => {
+        (ModuleType::Wasm, DenoCompileModuleSource::Bytes(self.data))
+      }
+      // just assume javascript if we made it here
+      MediaType::Css | MediaType::SourceMap | MediaType::Unknown => (
+        ModuleType::JavaScript,
+        DenoCompileModuleSource::Bytes(self.data),
+      ),
+    };
+    (self.specifier, media_type, source)
+  }
+}
+
+enum RemoteModulesStoreSpecifierValue {
+  Data(usize),
+  Redirect(Url),
+}
+
+pub struct RemoteModulesStore {
+  specifiers: HashMap<Url, RemoteModulesStoreSpecifierValue>,
+  files_data: &'static [u8],
+}
+
+impl RemoteModulesStore {
+  fn build(data: &'static [u8]) -> Result<Self, AnyError> {
+    fn read_specifier(input: &[u8]) -> Result<(&[u8], (Url, u64)), AnyError> {
+      let (input, specifier) = read_string_lossy(input)?;
+      let specifier = Url::parse(&specifier)?;
+      let (input, offset) = read_u64(input)?;
+      Ok((input, (specifier, offset)))
+    }
+
+    fn read_redirect(input: &[u8]) -> Result<(&[u8], (Url, Url)), AnyError> {
+      let (input, from) = read_string_lossy(input)?;
+      let from = Url::parse(&from)?;
+      let (input, to) = read_string_lossy(input)?;
+      let to = Url::parse(&to)?;
+      Ok((input, (from, to)))
+    }
+
+    fn read_headers(
+      input: &[u8],
+    ) -> Result<(&[u8], HashMap<Url, RemoteModulesStoreSpecifierValue>), AnyError>
+    {
+      let (input, specifiers_len) = read_u32_as_usize(input)?;
+      let (mut input, redirects_len) = read_u32_as_usize(input)?;
+      let mut specifiers =
+        HashMap::with_capacity(specifiers_len + redirects_len);
+      for _ in 0..specifiers_len {
+        let (current_input, (specifier, offset)) =
+          read_specifier(input).context("reading specifier")?;
+        input = current_input;
+        specifiers.insert(
+          specifier,
+          RemoteModulesStoreSpecifierValue::Data(offset as usize),
+        );
+      }
+
+      for _ in 0..redirects_len {
+        let (current_input, (from, to)) = read_redirect(input)?;
+        input = current_input;
+        specifiers.insert(from, RemoteModulesStoreSpecifierValue::Redirect(to));
+      }
+
+      Ok((input, specifiers))
+    }
+
+    let (files_data, specifiers) = read_headers(data)?;
+
+    Ok(Self {
+      specifiers,
+      files_data,
+    })
+  }
+
+  pub fn resolve_specifier<'a>(
+    &'a self,
+    specifier: &'a Url,
+  ) -> Result<Option<&'a Url>, AnyError> {
+    let mut count = 0;
+    let mut current = specifier;
+    loop {
+      if count > 10 {
+        bail!("Too many redirects resolving '{}'", specifier);
+      }
+      match self.specifiers.get(current) {
+        Some(RemoteModulesStoreSpecifierValue::Redirect(to)) => {
+          current = to;
+          count += 1;
+        }
+        Some(RemoteModulesStoreSpecifierValue::Data(_)) => {
+          return Ok(Some(current));
+        }
+        None => {
+          return Ok(None);
+        }
+      }
+    }
+  }
+
+  pub fn read<'a>(
+    &'a self,
+    original_specifier: &'a Url,
+  ) -> Result<Option<DenoCompileModuleData<'a>>, AnyError> {
+    let mut count = 0;
+    let mut specifier = original_specifier;
+    loop {
+      if count > 10 {
+        bail!("Too many redirects resolving '{}'", original_specifier);
+      }
+      match self.specifiers.get(specifier) {
+        Some(RemoteModulesStoreSpecifierValue::Redirect(to)) => {
+          specifier = to;
+          count += 1;
+        }
+        Some(RemoteModulesStoreSpecifierValue::Data(offset)) => {
+          let input = &self.files_data[*offset..];
+          let (input, media_type_byte) = read_bytes(input, 1)?;
+          let media_type = deserialize_media_type(media_type_byte[0])?;
+          let (input, len) = read_u64(input)?;
+          let (_input, data) = read_bytes(input, len as usize)?;
+          return Ok(Some(DenoCompileModuleData {
+            specifier,
+            media_type,
+            data: Cow::Borrowed(data),
+          }));
+        }
+        None => {
+          return Ok(None);
+        }
+      }
+    }
+  }
+}
+
+fn serialize_npm_snapshot(
+  mut snapshot: SerializedNpmResolutionSnapshot,
+) -> Vec<u8> {
+  fn append_string(bytes: &mut Vec<u8>, string: &str) {
+    let len = string.len() as u32;
+    bytes.extend_from_slice(&len.to_le_bytes());
+    bytes.extend_from_slice(string.as_bytes());
+  }
+
+  snapshot.packages.sort_by(|a, b| a.id.cmp(&b.id)); // determinism
+  let ids_to_stored_ids = snapshot
+    .packages
+    .iter()
+    .enumerate()
+    .map(|(i, pkg)| (&pkg.id, i as u32))
+    .collect::<HashMap<_, _>>();
+
+  let mut root_packages: Vec<_> = snapshot.root_packages.iter().collect();
+  root_packages.sort();
+  let mut bytes = Vec::new();
+
+  bytes.extend_from_slice(&(snapshot.packages.len() as u32).to_le_bytes());
+  for pkg in &snapshot.packages {
+    append_string(&mut bytes, &pkg.id.as_serialized());
+  }
+
+  bytes.extend_from_slice(&(root_packages.len() as u32).to_le_bytes());
+  for (req, id) in root_packages {
+    append_string(&mut bytes, &req.to_string());
+    let id = ids_to_stored_ids.get(&id).unwrap();
+    bytes.extend_from_slice(&id.to_le_bytes());
+  }
+
+  for pkg in &snapshot.packages {
+    let deps_len = pkg.dependencies.len() as u32;
+    bytes.extend_from_slice(&deps_len.to_le_bytes());
+    let mut deps: Vec<_> = pkg.dependencies.iter().collect();
+    deps.sort();
+    for (req, id) in deps {
+      append_string(&mut bytes, req);
+      let id = ids_to_stored_ids.get(&id).unwrap();
+      bytes.extend_from_slice(&id.to_le_bytes());
+    }
+  }
+
+  bytes
+}
+
+fn deserialize_npm_snapshot(
+  input: &[u8],
+) -> Result<ValidSerializedNpmResolutionSnapshot, AnyError> {
+  fn parse_id(input: &[u8]) -> Result<(&[u8], NpmPackageId), AnyError> {
+    let (input, id) = read_string_lossy(input)?;
+    let id = NpmPackageId::from_serialized(&id)?;
+    Ok((input, id))
+  }
+
+  #[allow(clippy::needless_lifetimes)] // clippy bug
+  fn parse_root_package<'a>(
+    id_to_npm_id: &'a impl Fn(usize) -> Result<NpmPackageId, AnyError>,
+  ) -> impl Fn(&[u8]) -> Result<(&[u8], (PackageReq, NpmPackageId)), AnyError> + 'a
+  {
+    |input| {
+      let (input, req) = read_string_lossy(input)?;
+      let req = PackageReq::from_str(&req)?;
+      let (input, id) = read_u32_as_usize(input)?;
+      Ok((input, (req, id_to_npm_id(id)?)))
+    }
+  }
+
+  #[allow(clippy::needless_lifetimes)] // clippy bug
+  fn parse_package_dep<'a>(
+    id_to_npm_id: &'a impl Fn(usize) -> Result<NpmPackageId, AnyError>,
+  ) -> impl Fn(&[u8]) -> Result<(&[u8], (String, NpmPackageId)), AnyError> + 'a
+  {
+    |input| {
+      let (input, req) = read_string_lossy(input)?;
+      let (input, id) = read_u32_as_usize(input)?;
+      Ok((input, (req.into_owned(), id_to_npm_id(id)?)))
+    }
+  }
+
+  fn parse_package<'a>(
+    input: &'a [u8],
+    id: NpmPackageId,
+    id_to_npm_id: &impl Fn(usize) -> Result<NpmPackageId, AnyError>,
+  ) -> Result<(&'a [u8], SerializedNpmResolutionSnapshotPackage), AnyError> {
+    let (input, deps_len) = read_u32_as_usize(input)?;
+    let (input, dependencies) =
+      parse_hashmap_n_times(input, deps_len, parse_package_dep(id_to_npm_id))?;
+    Ok((
+      input,
+      SerializedNpmResolutionSnapshotPackage {
+        id,
+        system: Default::default(),
+        dist: Default::default(),
+        dependencies,
+        optional_dependencies: Default::default(),
+        bin: None,
+        scripts: Default::default(),
+        deprecated: Default::default(),
+      },
+    ))
+  }
+
+  let (input, packages_len) = read_u32_as_usize(input)?;
+
+  // get a hashmap of all the npm package ids to their serialized ids
+  let (input, data_ids_to_npm_ids) =
+    parse_vec_n_times(input, packages_len, parse_id)
+      .context("deserializing id")?;
+  let data_id_to_npm_id = |id: usize| {
+    data_ids_to_npm_ids
+      .get(id)
+      .cloned()
+      .ok_or_else(|| deno_core::anyhow::anyhow!("Invalid npm package id"))
+  };
+
+  let (input, root_packages_len) = read_u32_as_usize(input)?;
+  let (input, root_packages) = parse_hashmap_n_times(
+    input,
+    root_packages_len,
+    parse_root_package(&data_id_to_npm_id),
+  )
+  .context("deserializing root package")?;
+  let (input, packages) =
+    parse_vec_n_times_with_index(input, packages_len, |input, index| {
+      parse_package(input, data_id_to_npm_id(index)?, &data_id_to_npm_id)
+    })
+    .context("deserializing package")?;
+
+  if !input.is_empty() {
+    bail!("Unexpected data left over");
+  }
+
+  Ok(
+    SerializedNpmResolutionSnapshot {
+      packages,
+      root_packages,
+    }
+    // this is ok because we have already verified that all the
+    // identifiers found in the snapshot are valid via the
+    // npm package id -> npm package id mapping
+    .into_valid_unsafe(),
+  )
+}
+
+fn serialize_media_type(media_type: MediaType) -> u8 {
+  match media_type {
+    MediaType::JavaScript => 0,
+    MediaType::Jsx => 1,
+    MediaType::Mjs => 2,
+    MediaType::Cjs => 3,
+    MediaType::TypeScript => 4,
+    MediaType::Mts => 5,
+    MediaType::Cts => 6,
+    MediaType::Dts => 7,
+    MediaType::Dmts => 8,
+    MediaType::Dcts => 9,
+    MediaType::Tsx => 10,
+    MediaType::Json => 11,
+    MediaType::Wasm => 12,
+    MediaType::Css => 13,
+    MediaType::SourceMap => 14,
+    MediaType::Unknown => 15,
+  }
+}
+
+fn deserialize_media_type(value: u8) -> Result<MediaType, AnyError> {
+  match value {
+    0 => Ok(MediaType::JavaScript),
+    1 => Ok(MediaType::Jsx),
+    2 => Ok(MediaType::Mjs),
+    3 => Ok(MediaType::Cjs),
+    4 => Ok(MediaType::TypeScript),
+    5 => Ok(MediaType::Mts),
+    6 => Ok(MediaType::Cts),
+    7 => Ok(MediaType::Dts),
+    8 => Ok(MediaType::Dmts),
+    9 => Ok(MediaType::Dcts),
+    10 => Ok(MediaType::Tsx),
+    11 => Ok(MediaType::Json),
+    12 => Ok(MediaType::Wasm),
+    13 => Ok(MediaType::Css),
+    14 => Ok(MediaType::SourceMap),
+    15 => Ok(MediaType::Unknown),
+    _ => bail!("Unknown media type value: {}", value),
+  }
+}
+
+fn parse_hashmap_n_times<TKey: std::cmp::Eq + std::hash::Hash, TValue>(
+  mut input: &[u8],
+  times: usize,
+  parse: impl Fn(&[u8]) -> Result<(&[u8], (TKey, TValue)), AnyError>,
+) -> Result<(&[u8], HashMap<TKey, TValue>), AnyError> {
+  let mut results = HashMap::with_capacity(times);
+  for _ in 0..times {
+    let result = parse(input);
+    let (new_input, (key, value)) = result?;
+    results.insert(key, value);
+    input = new_input;
+  }
+  Ok((input, results))
+}
+
+fn parse_vec_n_times<TResult>(
+  input: &[u8],
+  times: usize,
+  parse: impl Fn(&[u8]) -> Result<(&[u8], TResult), AnyError>,
+) -> Result<(&[u8], Vec<TResult>), AnyError> {
+  parse_vec_n_times_with_index(input, times, |input, _index| parse(input))
+}
+
+fn parse_vec_n_times_with_index<TResult>(
+  mut input: &[u8],
+  times: usize,
+  parse: impl Fn(&[u8], usize) -> Result<(&[u8], TResult), AnyError>,
+) -> Result<(&[u8], Vec<TResult>), AnyError> {
+  let mut results = Vec::with_capacity(times);
+  for i in 0..times {
+    let result = parse(input, i);
+    let (new_input, result) = result?;
+    results.push(result);
+    input = new_input;
+  }
+  Ok((input, results))
+}
+
+fn read_bytes(input: &[u8], len: usize) -> Result<(&[u8], &[u8]), AnyError> {
+  if input.len() < len {
+    bail!("Unexpected end of data.",);
+  }
+  let (len_bytes, input) = input.split_at(len);
+  Ok((input, len_bytes))
+}
+
+fn read_string_lossy(input: &[u8]) -> Result<(&[u8], Cow<str>), AnyError> {
+  let (input, str_len) = read_u32_as_usize(input)?;
+  let (input, data_bytes) = read_bytes(input, str_len)?;
+  Ok((input, String::from_utf8_lossy(data_bytes)))
+}
+
+fn read_u32_as_usize(input: &[u8]) -> Result<(&[u8], usize), AnyError> {
+  let (input, len_bytes) = read_bytes(input, 4)?;
+  let len = u32::from_le_bytes(len_bytes.try_into()?);
+  Ok((input, len as usize))
+}
+
+fn read_u64(input: &[u8]) -> Result<(&[u8], u64), AnyError> {
+  let (input, len_bytes) = read_bytes(input, 8)?;
+  let len = u64::from_le_bytes(len_bytes.try_into()?);
+  Ok((input, len))
+}