[pbs-devel] [PATCH v4 proxmox-backup 20/58] client: helper: add helpers for creating reader instances

[Christian Ebner]

Add module to place helper methods which need to be used in different
submodules of the client.

Add `get_pxar_fuse_reader`, `get_buffered_pxar_reader` and
`get_pxar_fuse_accessor` to create reader instances to access pxar
archives.

Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---
 proxmox-backup-client/src/helper.rs | 75 +++++++++++++++++++++++++++++
 proxmox-backup-client/src/main.rs   |  2 +
 2 files changed, 77 insertions(+)
 create mode 100644 proxmox-backup-client/src/helper.rs

diff --git a/proxmox-backup-client/src/helper.rs b/proxmox-backup-client/src/helper.rs
new file mode 100644
index 000000000..00b3ce362
--- /dev/null
+++ b/proxmox-backup-client/src/helper.rs
@@ -0,0 +1,75 @@
+use std::sync::Arc;
+
+use anyhow::Error;
+use pbs_client::{BackupReader, RemoteChunkReader};
+use pbs_datastore::BackupManifest;
+use pbs_tools::crypt_config::CryptConfig;
+
+use crate::{BufferedDynamicReadAt, BufferedDynamicReader, IndexFile};
+
+pub(crate) async fn get_pxar_fuse_accessor(
+    archive_name: &str,
+    payload_archive_name: Option<&str>,
+    client: Arc<BackupReader>,
+    manifest: &BackupManifest,
+    crypt_config: Option<Arc<CryptConfig>>,
+) -> Result<pbs_pxar_fuse::Accessor, Error> {
+    let (reader, archive_size) = get_pxar_fuse_reader(
+        &archive_name,
+        client.clone(),
+        &manifest,
+        crypt_config.clone(),
+    )
+    .await?;
+
+    let accessor = if let Some(payload_archive_name) = payload_archive_name {
+        let (payload_reader, payload_size) = get_pxar_fuse_reader(
+            payload_archive_name,
+            client.clone(),
+            &manifest,
+            crypt_config.clone(),
+        )
+        .await?;
+        pbs_pxar_fuse::Accessor::new(reader, archive_size, Some((payload_reader, payload_size)))
+            .await?
+    } else {
+        pbs_pxar_fuse::Accessor::new(reader, archive_size, None).await?
+    };
+
+    Ok(accessor)
+}
+
+pub(crate) async fn get_pxar_fuse_reader(
+    archive_name: &str,
+    client: Arc<BackupReader>,
+    manifest: &BackupManifest,
+    crypt_config: Option<Arc<CryptConfig>>,
+) -> Result<(pbs_pxar_fuse::Reader, u64), Error> {
+    let reader = get_buffered_pxar_reader(archive_name, client, manifest, crypt_config).await?;
+    let archive_size = reader.archive_size();
+    let reader: pbs_pxar_fuse::Reader = Arc::new(BufferedDynamicReadAt::new(reader));
+
+    Ok((reader, archive_size))
+}
+
+pub(crate) async fn get_buffered_pxar_reader(
+    archive_name: &str,
+    client: Arc<BackupReader>,
+    manifest: &BackupManifest,
+    crypt_config: Option<Arc<CryptConfig>>,
+) -> Result<BufferedDynamicReader<RemoteChunkReader>, Error> {
+    let index = client
+        .download_dynamic_index(&manifest, &archive_name)
+        .await?;
+
+    let most_used = index.find_most_used_chunks(8);
+    let file_info = manifest.lookup_file_info(&archive_name)?;
+    let chunk_reader = RemoteChunkReader::new(
+        client.clone(),
+        crypt_config.clone(),
+        file_info.chunk_crypt_mode(),
+        most_used,
+    );
+
+    Ok(BufferedDynamicReader::new(index, chunk_reader))
+}
diff --git a/proxmox-backup-client/src/main.rs b/proxmox-backup-client/src/main.rs
index ab7d316d4..b81719dad 100644
--- a/proxmox-backup-client/src/main.rs
+++ b/proxmox-backup-client/src/main.rs
@@ -72,6 +72,8 @@ mod catalog;
 pub use catalog::*;
 mod snapshot;
 pub use snapshot::*;
+mod helper;
+pub(crate) use helper::*;
 pub mod key;
 pub mod namespace;
 
-- 
2.39.2