src/backup/data_blob.rs: new load_from_reader(), which verifies the CRC

And make verify_crc private for now. We always call load_from_reader() to
verify the CRC.

Also add load_chunk() to datastore.rs (from chunk_store::read_chunk())

src/client/backup_reader.rs

@@ -129,8 +129,7 @@ impl BackupReader {
 
         let mut raw_data = Vec::with_capacity(64 * 1024);
         self.download(MANIFEST_BLOB_NAME, &mut raw_data).await?;
-        let blob = DataBlob::from_raw(raw_data)?;
-        blob.verify_crc()?;
+        let blob = DataBlob::load_from_reader(&mut &raw_data[..])?;
         let data = blob.decode(None)?;
 
         let manifest = BackupManifest::from_data(&data[..], self.crypt_config.as_ref().map(Arc::as_ref))?;

src/client/backup_writer.rs

@@ -479,8 +479,7 @@ impl BackupWriter {
         let param = json!({ "archive-name": MANIFEST_BLOB_NAME });
         self.h2.download("previous", Some(param), &mut raw_data).await?;
 
-        let blob = DataBlob::from_raw(raw_data)?;
-        blob.verify_crc()?;
+        let blob = DataBlob::load_from_reader(&mut &raw_data[..])?;
         let data = blob.decode(self.crypt_config.as_ref().map(Arc::as_ref))?;
 
         let manifest = BackupManifest::from_data(&data[..], self.crypt_config.as_ref().map(Arc::as_ref))?;

src/client/pull.rs

@@ -174,16 +174,14 @@ async fn pull_snapshot(
             };
         },
     };
-    let tmp_manifest_blob = DataBlob::load(&mut tmp_manifest_file)?;
-    tmp_manifest_blob.verify_crc()?;
+    let tmp_manifest_blob = DataBlob::load_from_reader(&mut tmp_manifest_file)?;
 
     if manifest_name.exists() {
         let manifest_blob = proxmox::try_block!({
             let mut manifest_file = std::fs::File::open(&manifest_name)
                 .map_err(|err| format_err!("unable to open local manifest {:?} - {}", manifest_name, err))?;
 
-            let manifest_blob = DataBlob::load(&mut manifest_file)?;
-            manifest_blob.verify_crc()?;
+            let manifest_blob = DataBlob::load_from_reader(&mut manifest_file)?;
             Ok(manifest_blob)
         }).map_err(|err: Error| {
             format_err!("unable to read local manifest {:?} - {}", manifest_name, err)

src/client/remote_chunk_reader.rs

@@ -42,8 +42,9 @@ impl RemoteChunkReader {
             .download_chunk(&digest, &mut chunk_data)
             .await?;
 
-        let chunk = DataBlob::from_raw(chunk_data)?;
-        chunk.verify_crc()?;
+        let chunk = DataBlob::load_from_reader(&mut &chunk_data[..])?;
+        
+        // fixme: verify digest?
 
         Ok(chunk)
     }