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Diffstat (limited to 'tvix/glue/src/fetchers.rs')
| -rw-r--r-- | tvix/glue/src/fetchers.rs | 387 |
1 files changed, 387 insertions, 0 deletions
diff --git a/tvix/glue/src/fetchers.rs b/tvix/glue/src/fetchers.rs new file mode 100644 index 000000000000..977be4a203af --- /dev/null +++ b/tvix/glue/src/fetchers.rs @@ -0,0 +1,387 @@ +use futures::TryStreamExt; +use md5::Md5; +use nix_compat::{ + nixhash::{CAHash, HashAlgo, NixHash}, + store_path::{build_ca_path, BuildStorePathError, StorePathRef}, +}; +use sha1::Sha1; +use sha2::{digest::Output, Digest, Sha256, Sha512}; +use tokio::io::{AsyncBufRead, AsyncRead, AsyncWrite}; +use tokio_util::io::InspectReader; +use tracing::warn; +use tvix_castore::{ + blobservice::BlobService, + directoryservice::DirectoryService, + proto::{node::Node, FileNode}, +}; +use tvix_store::{pathinfoservice::PathInfoService, proto::PathInfo}; + +use crate::{builtins::FetcherError, decompression::DecompressedReader}; + +/// Representing options for doing a fetch. +#[derive(Clone, Debug)] +pub enum Fetch { + /// Fetch a literal file from the given URL, with an optional expected + /// NixHash of it. + /// TODO: check if this is *always* sha256, and if so, make it [u8; 32]. + URL(String, Option<NixHash>), + + /// Fetch a tarball from the given URL and unpack. + /// The file must be a tape archive (.tar) compressed with gzip, bzip2 or xz. + /// The top-level path component of the files in the tarball is removed, + /// so it is best if the tarball contains a single directory at top level. + /// Optionally, a sha256 digest can be provided to verify the unpacked + /// contents against. + Tarball(String, Option<[u8; 32]>), + + /// TODO + Git(), +} + +impl Fetch { + /// If the [Fetch] contains an expected hash upfront, returns the resulting + /// store path. + /// This doesn't do any fetching. + pub fn store_path<'a>( + &self, + name: &'a str, + ) -> Result<Option<StorePathRef<'a>>, BuildStorePathError> { + let ca_hash = match self { + Fetch::URL(_, Some(nixhash)) => CAHash::Flat(nixhash.clone()), + Fetch::Tarball(_, Some(nar_sha256)) => CAHash::Nar(NixHash::Sha256(*nar_sha256)), + _ => return Ok(None), + }; + + // calculate the store path of this fetch + build_ca_path(name, &ca_hash, Vec::<String>::new(), false).map(Some) + } +} + +/// Knows how to fetch a given [Fetch]. +pub struct Fetcher<BS, DS, PS> { + http_client: reqwest::Client, + blob_service: BS, + directory_service: DS, + path_info_service: PS, +} + +impl<BS, DS, PS> Fetcher<BS, DS, PS> { + pub fn new(blob_service: BS, directory_service: DS, path_info_service: PS) -> Self { + Self { + http_client: reqwest::Client::new(), + blob_service, + directory_service, + path_info_service, + } + } + + /// Constructs a HTTP request to the passed URL, and returns a AsyncReadBuf to it. + async fn download<'a>( + &self, + url: &str, + ) -> Result<impl AsyncBufRead + Unpin + 'a, reqwest::Error> { + let resp = self.http_client.get(url).send().await?; + Ok(tokio_util::io::StreamReader::new( + resp.bytes_stream().map_err(|e| { + let e = e.without_url(); + warn!(%e, "failed to get response body"); + std::io::Error::new(std::io::ErrorKind::BrokenPipe, e) + }), + )) + } +} + +/// Copies all data from the passed reader to the passed writer. +/// Afterwards, it also returns the resulting [Digest], as well as the number of +/// bytes copied. +/// The exact hash function used is left generic over all [Digest]. +async fn hash<D: Digest + std::io::Write>( + mut r: impl AsyncRead + Unpin, + mut w: impl AsyncWrite + Unpin, +) -> std::io::Result<(Output<D>, u64)> { + let mut hasher = D::new(); + let bytes_copied = tokio::io::copy( + &mut InspectReader::new(&mut r, |d| hasher.write_all(d).unwrap()), + &mut w, + ) + .await?; + Ok((hasher.finalize(), bytes_copied)) +} + +impl<BS, DS, PS> Fetcher<BS, DS, PS> +where + BS: AsRef<(dyn BlobService + 'static)> + Send + Sync, + DS: AsRef<(dyn DirectoryService + 'static)>, + PS: PathInfoService, +{ + /// Ingest the data from a specified [Fetch]. + /// On success, return the root node, a content digest and length. + /// Returns an error if there was a failure during fetching, or the contents + /// didn't match the previously communicated hash contained inside the FetchArgs. + pub async fn ingest(&self, fetch: Fetch) -> Result<(Node, CAHash, u64), FetcherError> { + match fetch { + Fetch::URL(url, exp_nixhash) => { + // Construct a AsyncRead reading from the data as its downloaded. + let mut r = self.download(&url).await?; + + // Construct a AsyncWrite to write into the BlobService. + let mut blob_writer = self.blob_service.open_write().await; + + // Copy the contents from the download reader to the blob writer. + // Calculate the digest of the file received, depending on the + // communicated expected hash (or sha256 if none provided). + let (actual_nixhash, blob_size) = match exp_nixhash + .as_ref() + .map(NixHash::algo) + .unwrap_or_else(|| HashAlgo::Sha256) + { + HashAlgo::Sha256 => hash::<Sha256>(&mut r, &mut blob_writer).await.map( + |(digest, bytes_written)| (NixHash::Sha256(digest.into()), bytes_written), + )?, + HashAlgo::Md5 => hash::<Md5>(&mut r, &mut blob_writer).await.map( + |(digest, bytes_written)| (NixHash::Md5(digest.into()), bytes_written), + )?, + HashAlgo::Sha1 => hash::<Sha1>(&mut r, &mut blob_writer).await.map( + |(digest, bytes_written)| (NixHash::Sha1(digest.into()), bytes_written), + )?, + HashAlgo::Sha512 => hash::<Sha512>(&mut r, &mut blob_writer).await.map( + |(digest, bytes_written)| { + (NixHash::Sha512(Box::new(digest.into())), bytes_written) + }, + )?, + }; + + if let Some(exp_nixhash) = exp_nixhash { + if exp_nixhash != actual_nixhash { + return Err(FetcherError::HashMismatch { + url, + wanted: exp_nixhash, + got: actual_nixhash, + }); + } + } + + // Construct and return the FileNode describing the downloaded contents. + Ok(( + Node::File(FileNode { + name: vec![].into(), + digest: blob_writer.close().await?.into(), + size: blob_size, + executable: false, + }), + CAHash::Flat(actual_nixhash), + blob_size, + )) + } + Fetch::Tarball(url, exp_nar_sha256) => { + // Construct a AsyncRead reading from the data as its downloaded. + let r = self.download(&url).await?; + + // Pop compression. + let r = DecompressedReader::new(r); + // Open the archive. + let archive = tokio_tar::Archive::new(r); + + // Ingest the archive, get the root node + let node = tvix_castore::import::archive::ingest_archive( + &self.blob_service, + &self.directory_service, + archive, + ) + .await?; + + // If an expected NAR sha256 was provided, compare with the one + // calculated from our root node. + // Even if no expected NAR sha256 has been provided, we need + // the actual one later. + let (nar_size, actual_nar_sha256) = self + .path_info_service + .calculate_nar(&node) + .await + .map_err(|e| { + // convert the generic Store error to an IO error. + FetcherError::Io(e.into()) + })?; + + if let Some(exp_nar_sha256) = exp_nar_sha256 { + if exp_nar_sha256 != actual_nar_sha256 { + return Err(FetcherError::HashMismatch { + url, + wanted: NixHash::Sha256(exp_nar_sha256), + got: NixHash::Sha256(actual_nar_sha256), + }); + } + } + + Ok(( + node, + CAHash::Nar(NixHash::Sha256(actual_nar_sha256)), + nar_size, + )) + } + Fetch::Git() => todo!(), + } + } + + /// Ingests the data from a specified [Fetch], persists the returned node + /// in the PathInfoService, and returns the calculated StorePath, as well as + /// the root node pointing to the contents. + /// The root node can be used to descend into the data without doing the + /// lookup to the PathInfoService again. + pub async fn ingest_and_persist<'a>( + &self, + name: &'a str, + fetch: Fetch, + ) -> Result<(StorePathRef<'a>, Node), FetcherError> { + // Fetch file, return the (unnamed) (File)Node of its contents, ca hash and filesize. + let (mut node, ca_hash, size) = self.ingest(fetch).await?; + + // Calculate the store path to return later, which is done with the ca_hash. + let store_path = build_ca_path(name, &ca_hash, Vec::<String>::new(), false)?; + + // Rename the node name to match the Store Path. + if let Node::File(file_node) = &mut node { + file_node.name = store_path.to_string().into(); + } else { + unreachable!("Tvix bug: do_fetch for URL returned non-FileNode"); + } + + // If the resulting hash is not a CAHash::Nar, we also need to invoke + // `calculate_nar` to calculate this representation, as it's required in + // the [PathInfo]. + let (nar_size, nar_sha256) = match &ca_hash { + CAHash::Flat(_nix_hash) => self + .path_info_service + .calculate_nar(&node) + .await + .map_err(|e| FetcherError::Io(e.into()))?, + CAHash::Nar(NixHash::Sha256(nar_sha256)) => (size, *nar_sha256), + CAHash::Nar(_) => unreachable!("Tvix bug: fetch returned non-sha256 CAHash::Nar"), + CAHash::Text(_) => unreachable!("Tvix bug: fetch returned CAHash::Text"), + }; + + // Construct the PathInfo and persist it. + let path_info = PathInfo { + node: Some(tvix_castore::proto::Node { node: Some(node) }), + references: vec![], + narinfo: Some(tvix_store::proto::NarInfo { + nar_size, + nar_sha256: nar_sha256.to_vec().into(), + signatures: vec![], + reference_names: vec![], + deriver: None, + ca: Some(ca_hash.into()), + }), + }; + + let path_info = self + .path_info_service + .put(path_info) + .await + .map_err(|e| FetcherError::Io(e.into()))?; + + Ok((store_path, path_info.node.unwrap().node.unwrap())) + } +} + +/// Attempts to mimic `nix::libutil::baseNameOf` +pub(crate) fn url_basename(s: &str) -> &str { + if s.is_empty() { + return ""; + } + + let mut last = s.len() - 1; + if s.chars().nth(last).unwrap() == '/' && last > 0 { + last -= 1; + } + + if last == 0 { + return ""; + } + + let pos = match s[..=last].rfind('/') { + Some(pos) => { + if pos == last - 1 { + 0 + } else { + pos + } + } + None => 0, + }; + + &s[(pos + 1)..=last] +} + +#[cfg(test)] +mod tests { + mod fetch { + use nix_compat::nixbase32; + + use crate::fetchers::Fetch; + + use super::super::*; + + #[test] + fn fetchurl_store_path() { + let url = "https://raw.githubusercontent.com/aaptel/notmuch-extract-patch/f732a53e12a7c91a06755ebfab2007adc9b3063b/notmuch-extract-patch"; + let exp_nixhash = NixHash::Sha256( + nixbase32::decode_fixed("0nawkl04sj7psw6ikzay7kydj3dhd0fkwghcsf5rzaw4bmp4kbax") + .unwrap(), + ); + + let fetch = Fetch::URL(url.into(), Some(exp_nixhash)); + assert_eq!( + "06qi00hylriyfm0nl827crgjvbax84mz-notmuch-extract-patch", + &fetch + .store_path("notmuch-extract-patch") + .unwrap() + .unwrap() + .to_string(), + ) + } + + #[test] + fn fetch_tarball_store_path() { + let url = "https://github.com/NixOS/nixpkgs/archive/91050ea1e57e50388fa87a3302ba12d188ef723a.tar.gz"; + let exp_nixbase32 = + nixbase32::decode_fixed("1hf6cgaci1n186kkkjq106ryf8mmlq9vnwgfwh625wa8hfgdn4dm") + .unwrap(); + let fetch = Fetch::Tarball(url.into(), Some(exp_nixbase32)); + + assert_eq!( + "7adgvk5zdfq4pwrhsm3n9lzypb12gw0g-source", + &fetch.store_path("source").unwrap().unwrap().to_string(), + ) + } + } + + mod url_basename { + use super::super::*; + + #[test] + fn empty_path() { + assert_eq!(url_basename(""), ""); + } + + #[test] + fn path_on_root() { + assert_eq!(url_basename("/dir"), "dir"); + } + + #[test] + fn relative_path() { + assert_eq!(url_basename("dir/foo"), "foo"); + } + + #[test] + fn root_with_trailing_slash() { + assert_eq!(url_basename("/"), ""); + } + + #[test] + fn trailing_slash() { + assert_eq!(url_basename("/dir/"), "dir"); + } + } +} |