use cpp bindings to make nar

src/store.rs

@@ -2,9 +2,13 @@ use std::{ffi::OsStr, os::unix::ffi::OsStrExt, sync::Arc};
 
 use anyhow::{Context, Result};
 use nix_compat::store_path::StorePath;
-use tokio::task;
+use tokio::{io::AsyncRead, task};
+use tokio_util::io::StreamReader;
 
-use crate::{bindings, path_info::PathInfo};
+use crate::{
+    bindings::{self, AsyncWriteAdapter},
+    path_info::PathInfo,
+};
 
 pub struct Store {
     inner: Arc<bindings::FfiNixStore>,
@@ -75,4 +79,20 @@ impl Store {
         .await
         .unwrap()
     }
+
+    pub fn nar_from_path(&self, store_path: StorePath<String>) -> impl AsyncRead {
+        let inner = self.inner.clone();
+        let (adapter, mut sender) = AsyncWriteAdapter::new();
+        let base_name = store_path.to_string().as_bytes().to_vec();
+
+        tokio::task::spawn_blocking(move || {
+            // Send all exceptions through the channel, and ignore errors
+            // during sending (the channel may have been closed).
+            if let Err(e) = inner.store().nar_from_path(base_name, sender.clone()) {
+                let _ = sender.rust_error(e);
+            }
+        });
+
+        StreamReader::new(adapter)
+    }
 }