Prepare MariaDB restore tests and recover backup disk space safely

lib/backup_set.py

@@ -99,9 +99,11 @@ def check_tar(path, roots):
     proc = subprocess.Popen(command, stdout=subprocess.PIPE)
     entries = {}
     hardlinks = []
+    expanded = 0
     try:
         with tarfile.open(fileobj=proc.stdout, mode="r|") as archive:
             for item in archive:
+                expanded += ((item.size + 4095) // 4096) * 4096 + 4096
                 name = member_name(item.name)
                 if not any(name == root or name.startswith(root + "/") for root in roots):
                     raise ValueError(f"Member outside component root: {name}")
@@ -128,6 +130,7 @@ def check_tar(path, roots):
             pass
         if proc.wait() != 0:
             raise ValueError(f"Decompression failed: {path}")
+        return expanded
     finally:
         proc.stdout.close()
         if proc.poll() is None:
@@ -291,9 +294,11 @@ def main():
         crypt(*args)
     elif op == "create":
         create(Path(args[0]), *args[1:])
-    elif op in ("verify", "metadata", "list"):
+    elif op in ("verify", "metadata", "list", "expanded"):
         data = load_set(Path(args[0]), metadata_only=op == "metadata")
-        if op == "verify":
+        if op == "expanded":
+            print(sum(check_tar(Path(args[0]) / item['file'], [item['root']]) for item in data['archives']))
+        elif op == "verify":
             for item in data["archives"]:
                 check_tar(Path(args[0]) / item["file"], [item["root"]])
             print(f"Verified: {data['run_id']} ({len(data['archives'])} archives)")