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-rw-r--r--tvix/Cargo.lock2
-rw-r--r--tvix/Cargo.nix11
-rw-r--r--tvix/glue/Cargo.toml2
-rw-r--r--tvix/glue/default.nix5
-rw-r--r--tvix/glue/src/builtins/derivation.rs41
-rw-r--r--tvix/glue/src/builtins/errors.rs30
-rw-r--r--tvix/glue/src/builtins/fetchers.rs257
-rw-r--r--tvix/glue/src/builtins/mod.rs3
-rw-r--r--tvix/glue/src/builtins/utils.rs36
-rw-r--r--tvix/glue/src/tvix_store_io.rs107
-rw-r--r--tvix/nix-compat/src/store_path/mod.rs14
11 files changed, 454 insertions, 54 deletions
diff --git a/tvix/Cargo.lock b/tvix/Cargo.lock
index 39d726550d..4eda0fd016 100644
--- a/tvix/Cargo.lock
+++ b/tvix/Cargo.lock
@@ -3424,6 +3424,7 @@ dependencies = [
  "nix 0.27.1",
  "nix-compat",
  "pretty_assertions",
+ "reqwest",
  "rstest",
  "serde",
  "serde_json",
@@ -3432,6 +3433,7 @@ dependencies = [
  "test-case",
  "thiserror",
  "tokio",
+ "tokio-util",
  "tracing",
  "tvix-build",
  "tvix-castore",
diff --git a/tvix/Cargo.nix b/tvix/Cargo.nix
index f0e76c85e3..bc01e1a76b 100644
--- a/tvix/Cargo.nix
+++ b/tvix/Cargo.nix
@@ -10793,6 +10793,12 @@ rec {
             packageId = "nix-compat";
           }
           {
+            name = "reqwest";
+            packageId = "reqwest";
+            usesDefaultFeatures = false;
+            features = [ "rustls-tls-native-roots" ];
+          }
+          {
             name = "serde";
             packageId = "serde";
           }
@@ -10813,6 +10819,11 @@ rec {
             packageId = "tokio";
           }
           {
+            name = "tokio-util";
+            packageId = "tokio-util";
+            features = [ "io" "io-util" "compat" ];
+          }
+          {
             name = "tracing";
             packageId = "tracing";
           }
diff --git a/tvix/glue/Cargo.toml b/tvix/glue/Cargo.toml
index 5a0296f975..f4ebfe4906 100644
--- a/tvix/glue/Cargo.toml
+++ b/tvix/glue/Cargo.toml
@@ -10,12 +10,14 @@ bytes = "1.4.0"
 data-encoding = "2.3.3"
 futures = "0.3.30"
 nix-compat = { path = "../nix-compat" }
+reqwest = { version = "0.11.22", features = ["rustls-tls-native-roots"], default-features = false }
 tvix-build = { path = "../build", default-features = false, features = []}
 tvix-eval = { path = "../eval" }
 tvix-castore = { path = "../castore" }
 tvix-store = { path = "../store", default-features = false, features = []}
 tracing = "0.1.37"
 tokio = "1.28.0"
+tokio-util = { version = "0.7.9", features = ["io", "io-util", "compat"] }
 thiserror = "1.0.38"
 serde = "1.0.195"
 serde_json = "1.0"
diff --git a/tvix/glue/default.nix b/tvix/glue/default.nix
index 975b0a5a70..08f5c2228d 100644
--- a/tvix/glue/default.nix
+++ b/tvix/glue/default.nix
@@ -1,5 +1,8 @@
-{ depot, ... }:
+{ depot, pkgs, ... }:
 
 (depot.tvix.crates.workspaceMembers.tvix-glue.build.override {
   runTests = true;
+  testPreRun = ''
+    export SSL_CERT_FILE=${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt;
+  '';
 })
diff --git a/tvix/glue/src/builtins/derivation.rs b/tvix/glue/src/builtins/derivation.rs
index 71249f1c77..4ea9611a94 100644
--- a/tvix/glue/src/builtins/derivation.rs
+++ b/tvix/glue/src/builtins/derivation.rs
@@ -10,8 +10,7 @@ use std::rc::Rc;
 use tvix_eval::builtin_macros::builtins;
 use tvix_eval::generators::{self, emit_warning_kind, GenCo};
 use tvix_eval::{
-    AddContext, CatchableErrorKind, CoercionKind, ErrorKind, NixAttrs, NixContext,
-    NixContextElement, Value, WarningKind,
+    AddContext, ErrorKind, NixAttrs, NixContext, NixContextElement, Value, WarningKind,
 };
 
 // Constants used for strangely named fields in derivation inputs.
@@ -144,6 +143,8 @@ fn handle_fixed_output(
 pub(crate) mod derivation_builtins {
     use std::collections::BTreeMap;
 
+    use crate::builtins::utils::{select_string, strong_importing_coerce_to_string};
+
     use super::*;
     use bstr::ByteSlice;
     use nix_compat::store_path::hash_placeholder;
@@ -197,27 +198,6 @@ pub(crate) mod derivation_builtins {
         drv.outputs.insert("out".to_string(), Default::default());
         let mut input_context = NixContext::new();
 
-        #[inline]
-        async fn strong_importing_coerce_to_string(
-            co: &GenCo,
-            val: Value,
-        ) -> Result<NixString, CatchableErrorKind> {
-            let val = generators::request_force(co, val).await;
-            match generators::request_string_coerce(
-                co,
-                val,
-                CoercionKind {
-                    strong: true,
-                    import_paths: true,
-                },
-            )
-            .await
-            {
-                Err(cek) => Err(cek),
-                Ok(val_str) => Ok(val_str),
-            }
-        }
-
         /// Inserts a key and value into the drv.environment BTreeMap, and fails if the
         /// key did already exist before.
         fn insert_env(
@@ -385,21 +365,6 @@ pub(crate) mod derivation_builtins {
 
         // Configure fixed-output derivations if required.
         {
-            async fn select_string(
-                co: &GenCo,
-                attrs: &NixAttrs,
-                key: &str,
-            ) -> Result<Result<Option<String>, CatchableErrorKind>, ErrorKind> {
-                if let Some(attr) = attrs.select(key) {
-                    match strong_importing_coerce_to_string(co, attr.clone()).await {
-                        Err(cek) => return Ok(Err(cek)),
-                        Ok(str) => return Ok(Ok(Some(str.to_str()?.to_owned()))),
-                    }
-                }
-
-                Ok(Ok(None))
-            }
-
             let output_hash = match select_string(&co, &input, "outputHash")
                 .await
                 .context("evaluating the `outputHash` parameter")?
diff --git a/tvix/glue/src/builtins/errors.rs b/tvix/glue/src/builtins/errors.rs
index b606aa6a7c..c753a125e0 100644
--- a/tvix/glue/src/builtins/errors.rs
+++ b/tvix/glue/src/builtins/errors.rs
@@ -1,5 +1,8 @@
 //! Contains errors that can occur during evaluation of builtins in this crate
-use nix_compat::nixhash;
+use nix_compat::{
+    nixhash::{self, NixHash},
+    store_path::BuildStorePathError,
+};
 use std::rc::Rc;
 use thiserror::Error;
 
@@ -25,3 +28,28 @@ impl From<DerivationError> for tvix_eval::ErrorKind {
         tvix_eval::ErrorKind::TvixError(Rc::new(err))
     }
 }
+
+#[derive(Debug, Error)]
+pub enum FetcherError {
+    #[error("hash mismatch in file downloaded from {url}:\n  wanted: {wanted}\n     got: {got}")]
+    HashMismatch {
+        url: String,
+        wanted: NixHash,
+        got: NixHash,
+    },
+
+    #[error("Invalid hash type '{0}' for fetcher")]
+    InvalidHashType(&'static str),
+
+    #[error("Error in store path for fetcher output: {0}")]
+    StorePath(#[from] BuildStorePathError),
+
+    #[error(transparent)]
+    Http(#[from] reqwest::Error),
+}
+
+impl From<FetcherError> for tvix_eval::ErrorKind {
+    fn from(err: FetcherError) -> Self {
+        tvix_eval::ErrorKind::TvixError(Rc::new(err))
+    }
+}
diff --git a/tvix/glue/src/builtins/fetchers.rs b/tvix/glue/src/builtins/fetchers.rs
index 7a5d49a725..07074d93de 100644
--- a/tvix/glue/src/builtins/fetchers.rs
+++ b/tvix/glue/src/builtins/fetchers.rs
@@ -1,9 +1,189 @@
 //! Contains builtins that fetch paths from the Internet
 
 use crate::tvix_store_io::TvixStoreIO;
+use bstr::ByteSlice;
+use nix_compat::nixhash::{self, CAHash};
+use nix_compat::store_path::{build_ca_path, StorePathRef};
 use std::rc::Rc;
 use tvix_eval::builtin_macros::builtins;
-use tvix_eval::Value;
+use tvix_eval::generators::GenCo;
+use tvix_eval::{CatchableErrorKind, ErrorKind, NixContextElement, NixString, Value};
+
+use super::utils::select_string;
+use super::{DerivationError, FetcherError};
+
+/// Attempts to mimic `nix::libutil::baseNameOf`
+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]
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum HashMode {
+    Flat,
+    Recursive,
+}
+
+/// Struct representing the arguments passed to fetcher functions
+#[derive(Debug, PartialEq, Eq)]
+struct FetchArgs {
+    url: String,
+    name: String,
+    hash: Option<CAHash>,
+}
+
+impl FetchArgs {
+    pub fn new(
+        url: String,
+        name: Option<String>,
+        sha256: Option<String>,
+        mode: HashMode,
+    ) -> nixhash::Result<Self> {
+        Ok(Self {
+            name: name.unwrap_or_else(|| url_basename(&url).to_owned()),
+            url,
+            hash: sha256
+                .map(|h| {
+                    let hash = nixhash::from_str(&h, Some("sha256"))?;
+                    Ok(match mode {
+                        HashMode::Flat => Some(nixhash::CAHash::Flat(hash)),
+                        HashMode::Recursive => Some(nixhash::CAHash::Nar(hash)),
+                    })
+                })
+                .transpose()?
+                .flatten(),
+        })
+    }
+
+    fn store_path(&self) -> Result<Option<StorePathRef>, ErrorKind> {
+        let Some(h) = &self.hash else {
+            return Ok(None);
+        };
+        build_ca_path(&self.name, h, Vec::<String>::new(), false)
+            .map(Some)
+            .map_err(|e| FetcherError::from(e).into())
+    }
+
+    async fn extract(
+        co: &GenCo,
+        args: Value,
+        default_name: Option<&str>,
+        mode: HashMode,
+    ) -> Result<Result<Self, CatchableErrorKind>, ErrorKind> {
+        if let Ok(url) = args.to_str() {
+            return Ok(Ok(FetchArgs::new(
+                url.to_str()?.to_owned(),
+                None,
+                None,
+                mode,
+            )
+            .map_err(DerivationError::InvalidOutputHash)?));
+        }
+
+        let attrs = args.to_attrs().map_err(|_| ErrorKind::TypeError {
+            expected: "attribute set or string",
+            actual: args.type_of(),
+        })?;
+
+        let url = match select_string(co, &attrs, "url").await? {
+            Ok(s) => s.ok_or_else(|| ErrorKind::AttributeNotFound { name: "url".into() })?,
+            Err(cek) => return Ok(Err(cek)),
+        };
+        let name = match select_string(co, &attrs, "name").await? {
+            Ok(s) => s.or_else(|| default_name.map(|s| s.to_owned())),
+            Err(cek) => return Ok(Err(cek)),
+        };
+        let sha256 = match select_string(co, &attrs, "sha256").await? {
+            Ok(s) => s,
+            Err(cek) => return Ok(Err(cek)),
+        };
+
+        Ok(Ok(
+            FetchArgs::new(url, name, sha256, mode).map_err(DerivationError::InvalidOutputHash)?
+        ))
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum FetchMode {
+    Url,
+    Tarball,
+}
+
+impl From<FetchMode> for HashMode {
+    fn from(value: FetchMode) -> Self {
+        match value {
+            FetchMode::Url => HashMode::Flat,
+            FetchMode::Tarball => HashMode::Recursive,
+        }
+    }
+}
+
+impl FetchMode {
+    fn default_name(self) -> Option<&'static str> {
+        match self {
+            FetchMode::Url => None,
+            FetchMode::Tarball => Some("source"),
+        }
+    }
+}
+
+fn string_from_store_path(store_path: StorePathRef) -> NixString {
+    NixString::new_context_from(
+        NixContextElement::Plain(store_path.to_absolute_path()).into(),
+        store_path.to_absolute_path(),
+    )
+}
+
+async fn fetch(
+    state: Rc<TvixStoreIO>,
+    co: GenCo,
+    args: Value,
+    mode: FetchMode,
+) -> Result<Value, ErrorKind> {
+    let args = match FetchArgs::extract(&co, args, mode.default_name(), mode.into()).await? {
+        Ok(args) => args,
+        Err(cek) => return Ok(cek.into()),
+    };
+
+    if let Some(store_path) = args.store_path()? {
+        if state.store_path_exists(store_path).await? {
+            return Ok(string_from_store_path(store_path).into());
+        }
+    }
+
+    let hash = args.hash.as_ref().map(|h| h.hash());
+    let store_path = Rc::clone(&state).tokio_handle.block_on(state.fetch_url(
+        &args.url,
+        &args.name,
+        hash.as_deref(),
+    ))?;
+
+    Ok(string_from_store_path(store_path.as_ref()).into())
+}
 
 #[allow(unused_variables)] // for the `state` arg, for now
 #[builtins(state = "Rc<TvixStoreIO>")]
@@ -11,15 +191,14 @@ pub(crate) mod fetcher_builtins {
     use super::*;
 
     use tvix_eval::generators::Gen;
-    use tvix_eval::{generators::GenCo, ErrorKind};
 
     #[builtin("fetchurl")]
     async fn builtin_fetchurl(
         state: Rc<TvixStoreIO>,
         co: GenCo,
-        url: Value,
+        args: Value,
     ) -> Result<Value, ErrorKind> {
-        Err(ErrorKind::NotImplemented("fetchurl"))
+        fetch(state, co, args, FetchMode::Url).await
     }
 
     #[builtin("fetchTarball")]
@@ -28,7 +207,7 @@ pub(crate) mod fetcher_builtins {
         co: GenCo,
         args: Value,
     ) -> Result<Value, ErrorKind> {
-        Err(ErrorKind::NotImplemented("fetchTarball"))
+        fetch(state, co, args, FetchMode::Tarball).await
     }
 
     #[builtin("fetchGit")]
@@ -40,3 +219,71 @@ pub(crate) mod fetcher_builtins {
         Err(ErrorKind::NotImplemented("fetchGit"))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use std::str::FromStr;
+
+    use nix_compat::store_path::StorePath;
+
+    use super::*;
+
+    #[test]
+    fn fetchurl_store_path() {
+        let url = "https://raw.githubusercontent.com/aaptel/notmuch-extract-patch/f732a53e12a7c91a06755ebfab2007adc9b3063b/notmuch-extract-patch";
+        let sha256 = "0nawkl04sj7psw6ikzay7kydj3dhd0fkwghcsf5rzaw4bmp4kbax";
+        let args = FetchArgs::new(url.into(), None, Some(sha256.into()), HashMode::Flat).unwrap();
+
+        assert_eq!(
+            args.store_path().unwrap().unwrap().to_owned(),
+            StorePath::from_str("06qi00hylriyfm0nl827crgjvbax84mz-notmuch-extract-patch").unwrap()
+        )
+    }
+
+    #[test]
+    fn fetch_tarball_store_path() {
+        let url = "https://github.com/NixOS/nixpkgs/archive/91050ea1e57e50388fa87a3302ba12d188ef723a.tar.gz";
+        let sha256 = "1hf6cgaci1n186kkkjq106ryf8mmlq9vnwgfwh625wa8hfgdn4dm";
+        let args = FetchArgs::new(
+            url.into(),
+            Some("source".into()),
+            Some(sha256.into()),
+            HashMode::Recursive,
+        )
+        .unwrap();
+
+        assert_eq!(
+            args.store_path().unwrap().unwrap().to_owned(),
+            StorePath::from_str("7adgvk5zdfq4pwrhsm3n9lzypb12gw0g-source").unwrap()
+        )
+    }
+
+    mod url_basename {
+        use 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");
+        }
+    }
+}
diff --git a/tvix/glue/src/builtins/mod.rs b/tvix/glue/src/builtins/mod.rs
index c528bd4642..138a52633d 100644
--- a/tvix/glue/src/builtins/mod.rs
+++ b/tvix/glue/src/builtins/mod.rs
@@ -8,8 +8,9 @@ mod derivation;
 mod errors;
 mod fetchers;
 mod import;
+mod utils;
 
-pub use errors::DerivationError;
+pub use errors::{DerivationError, FetcherError};
 
 /// Adds derivation-related builtins to the passed [tvix_eval::Evaluation].
 ///
diff --git a/tvix/glue/src/builtins/utils.rs b/tvix/glue/src/builtins/utils.rs
new file mode 100644
index 0000000000..586169beeb
--- /dev/null
+++ b/tvix/glue/src/builtins/utils.rs
@@ -0,0 +1,36 @@
+use bstr::ByteSlice;
+use tvix_eval::{
+    generators::{self, GenCo},
+    CatchableErrorKind, CoercionKind, ErrorKind, NixAttrs, NixString, Value,
+};
+
+pub(super) async fn strong_importing_coerce_to_string(
+    co: &GenCo,
+    val: Value,
+) -> Result<NixString, CatchableErrorKind> {
+    let val = generators::request_force(co, val).await;
+    generators::request_string_coerce(
+        co,
+        val,
+        CoercionKind {
+            strong: true,
+            import_paths: true,
+        },
+    )
+    .await
+}
+
+pub(super) async fn select_string(
+    co: &GenCo,
+    attrs: &NixAttrs,
+    key: &str,
+) -> Result<Result<Option<String>, CatchableErrorKind>, ErrorKind> {
+    if let Some(attr) = attrs.select(key) {
+        match strong_importing_coerce_to_string(co, attr.clone()).await {
+            Err(cek) => return Ok(Err(cek)),
+            Ok(str) => return Ok(Ok(Some(str.to_str()?.to_owned()))),
+        }
+    }
+
+    Ok(Ok(None))
+}
diff --git a/tvix/glue/src/tvix_store_io.rs b/tvix/glue/src/tvix_store_io.rs
index c09f0098e4..30ab97c0ca 100644
--- a/tvix/glue/src/tvix_store_io.rs
+++ b/tvix/glue/src/tvix_store_io.rs
@@ -4,7 +4,12 @@ use async_recursion::async_recursion;
 use bytes::Bytes;
 use futures::Stream;
 use futures::{StreamExt, TryStreamExt};
+use nix_compat::nixhash::NixHash;
+use nix_compat::store_path::{build_ca_path, StorePathRef};
 use nix_compat::{nixhash::CAHash, store_path::StorePath};
+use sha2::{Digest, Sha256};
+use std::marker::Unpin;
+use std::rc::Rc;
 use std::{
     cell::RefCell,
     collections::BTreeSet,
@@ -15,17 +20,18 @@ use std::{
 use tokio::io::AsyncReadExt;
 use tracing::{error, instrument, warn, Level};
 use tvix_build::buildservice::BuildService;
-use tvix_eval::{EvalIO, FileType, StdIO};
+use tvix_eval::{ErrorKind, EvalIO, FileType, StdIO};
 use walkdir::DirEntry;
 
 use tvix_castore::{
     blobservice::BlobService,
     directoryservice::{self, DirectoryService},
-    proto::{node::Node, NamedNode},
+    proto::{node::Node, FileNode, NamedNode},
     B3Digest,
 };
 use tvix_store::{pathinfoservice::PathInfoService, proto::PathInfo};
 
+use crate::builtins::FetcherError;
 use crate::known_paths::KnownPaths;
 use crate::tvix_build::derivation_to_build_request;
 
@@ -51,7 +57,8 @@ pub struct TvixStoreIO {
     std_io: StdIO,
     #[allow(dead_code)]
     build_service: Arc<dyn BuildService>,
-    tokio_handle: tokio::runtime::Handle,
+    pub(crate) tokio_handle: tokio::runtime::Handle,
+    http_client: reqwest::Client,
     pub(crate) known_paths: RefCell<KnownPaths>,
 }
 
@@ -70,6 +77,7 @@ impl TvixStoreIO {
             std_io: StdIO {},
             build_service,
             tokio_handle,
+            http_client: reqwest::Client::new(),
             known_paths: Default::default(),
         }
     }
@@ -278,7 +286,7 @@ impl TvixStoreIO {
     /// with a [`tokio::runtime::Handle::block_on`] call for synchronicity.
     pub(crate) fn ingest_entries_sync<S>(&self, entries_stream: S) -> io::Result<Node>
     where
-        S: Stream<Item = DirEntry> + std::marker::Unpin,
+        S: Stream<Item = DirEntry> + Unpin,
     {
         self.tokio_handle.block_on(async move {
             tvix_castore::import::ingest_entries(
@@ -346,6 +354,97 @@ impl TvixStoreIO {
                 .await
         })
     }
+
+    pub async fn store_path_exists<'a>(&'a self, store_path: StorePathRef<'a>) -> io::Result<bool> {
+        Ok(self
+            .path_info_service
+            .as_ref()
+            .get(*store_path.digest())
+            .await?
+            .is_some())
+    }
+
+    pub async fn fetch_url(
+        &self,
+        url: &str,
+        name: &str,
+        hash: Option<&NixHash>,
+    ) -> Result<StorePath, ErrorKind> {
+        let resp = self
+            .http_client
+            .get(url)
+            .send()
+            .await
+            .map_err(FetcherError::from)?;
+        let mut sha = Sha256::new();
+        let mut data = tokio_util::io::StreamReader::new(
+            resp.bytes_stream()
+                .inspect_ok(|data| {
+                    sha.update(data);
+                })
+                .map_err(|e| {
+                    let e = e.without_url();
+                    warn!(%e, "failed to get response body");
+                    io::Error::new(io::ErrorKind::BrokenPipe, e.to_string())
+                }),
+        );
+
+        let mut blob = self.blob_service.open_write().await;
+        let size = tokio::io::copy(&mut data, blob.as_mut()).await?;
+        let blob_digest = blob.close().await?;
+        let got = NixHash::Sha256(sha.finalize().into());
+
+        let hash = CAHash::Flat(if let Some(wanted) = hash {
+            if *wanted != got {
+                return Err(FetcherError::HashMismatch {
+                    url: url.to_owned(),
+                    wanted: wanted.clone(),
+                    got,
+                }
+                .into());
+            }
+            wanted.clone()
+        } else {
+            got
+        });
+
+        let path = build_ca_path(name, &hash, Vec::<String>::new(), false)
+            .map_err(|e| io::Error::new(io::ErrorKind::Other, e))?;
+        let node = Node::File(FileNode {
+            name: path.to_string().into(),
+            digest: blob_digest.into(),
+            size,
+            executable: false,
+        });
+
+        let (nar_size, nar_sha256) = self
+            .path_info_service
+            .calculate_nar(&node)
+            .await
+            .map_err(|e| ErrorKind::TvixError(Rc::new(e)))?;
+
+        let path_info = PathInfo {
+            node: Some(tvix_castore::proto::Node {
+                node: Some(node.clone()),
+            }),
+            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((&hash).into()),
+            }),
+        };
+
+        self.path_info_service
+            .put(path_info)
+            .await
+            .map_err(|e| std::io::Error::new(io::ErrorKind::Other, e))?;
+
+        Ok(path.to_owned())
+    }
 }
 
 impl EvalIO for TvixStoreIO {
diff --git a/tvix/nix-compat/src/store_path/mod.rs b/tvix/nix-compat/src/store_path/mod.rs
index 836374b800..c744f1a46a 100644
--- a/tvix/nix-compat/src/store_path/mod.rs
+++ b/tvix/nix-compat/src/store_path/mod.rs
@@ -29,7 +29,7 @@ pub enum Error {
     #[error("Dash is missing between hash and name")]
     MissingDash,
     #[error("Hash encoding is invalid: {0}")]
-    InvalidHashEncoding(DecodeError),
+    InvalidHashEncoding(#[from] DecodeError),
     #[error("Invalid length")]
     InvalidLength,
     #[error(
@@ -67,6 +67,13 @@ impl StorePath {
     pub fn name(&self) -> &str {
         self.name.as_ref()
     }
+
+    pub fn as_ref(&self) -> StorePathRef<'_> {
+        StorePathRef {
+            digest: self.digest,
+            name: &self.name,
+        }
+    }
 }
 
 impl PartialOrd for StorePath {
@@ -176,7 +183,7 @@ impl Serialize for StorePath {
 /// Like [StorePath], but without a heap allocation for the name.
 /// Used by [StorePath] for parsing.
 ///
-#[derive(Debug, Eq, PartialEq)]
+#[derive(Debug, Eq, PartialEq, Clone, Copy)]
 pub struct StorePathRef<'a> {
     digest: [u8; DIGEST_SIZE],
     name: &'a str,
@@ -237,8 +244,7 @@ impl<'a> StorePathRef<'a> {
             Err(Error::InvalidLength)?
         }
 
-        let digest = nixbase32::decode_fixed(&s[..ENCODED_DIGEST_SIZE])
-            .map_err(Error::InvalidHashEncoding)?;
+        let digest = nixbase32::decode_fixed(&s[..ENCODED_DIGEST_SIZE])?;
 
         if s[ENCODED_DIGEST_SIZE] != b'-' {
             return Err(Error::MissingDash);