[pbs-devel] [RFC v2 proxmox-backup 19/36] api: datastore: refactor getting local chunk reader

[Christian Ebner <c.ebner@proxmox.com>]

Move the code to get the local chunk reader to a dedicated function
to make it reusable. The same code is required to get the local chunk
reader for the payload stream for split stream archives.

Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
---
changes since version 1:
- no changes

 src/api2/admin/datastore.rs | 37 +++++++++++++++++++++++++------------
 1 file changed, 25 insertions(+), 12 deletions(-)

diff --git a/src/api2/admin/datastore.rs b/src/api2/admin/datastore.rs
index a95031e7..843b9ce5 100644
--- a/src/api2/admin/datastore.rs
+++ b/src/api2/admin/datastore.rs
@@ -1653,6 +1653,29 @@ pub const API_METHOD_PXAR_FILE_DOWNLOAD: ApiMethod = ApiMethod::new(
     &Permission::Anybody,
 );
 
+fn get_local_pxar_reader(
+    datastore: Arc<DataStore>,
+    manifest: &BackupManifest,
+    backup_dir: &BackupDir,
+    pxar_name: &str,
+) -> Result<(LocalDynamicReadAt<LocalChunkReader>, u64), Error> {
+    let mut path = datastore.base_path();
+    path.push(backup_dir.relative_path());
+    path.push(pxar_name);
+
+    let index = DynamicIndexReader::open(&path)
+        .map_err(|err| format_err!("unable to read dynamic index '{:?}' - {}", &path, err))?;
+
+    let (csum, size) = index.compute_csum();
+    manifest.verify_file(pxar_name, &csum, size)?;
+
+    let chunk_reader = LocalChunkReader::new(datastore, None, CryptMode::None);
+    let reader = BufferedDynamicReader::new(index, chunk_reader);
+    let archive_size = reader.archive_size();
+
+    Ok((LocalDynamicReadAt::new(reader), archive_size))
+}
+
 pub fn pxar_file_download(
     _parts: Parts,
     _req_body: Body,
@@ -1697,20 +1720,10 @@ pub fn pxar_file_download(
             }
         }
 
-        let mut path = datastore.base_path();
-        path.push(backup_dir.relative_path());
-        path.push(pxar_name);
+        let (reader, archive_size) =
+            get_local_pxar_reader(datastore.clone(), &manifest, &backup_dir, &pxar_name)?;
 
-        let index = DynamicIndexReader::open(&path)
-            .map_err(|err| format_err!("unable to read dynamic index '{:?}' - {}", &path, err))?;
 
-        let (csum, size) = index.compute_csum();
-        manifest.verify_file(pxar_name, &csum, size)?;
-
-        let chunk_reader = LocalChunkReader::new(datastore, None, CryptMode::None);
-        let reader = BufferedDynamicReader::new(index, chunk_reader);
-        let archive_size = reader.archive_size();
-        let reader = LocalDynamicReadAt::new(reader);
 
         let decoder = Accessor::new(reader, archive_size).await?;
         let root = decoder.open_root().await?;
-- 
2.39.2