Implement spooling of byte stream to temp file

Added functionality to spool an async byte stream to a temporary file for improved upload handling.

custom_components/owncloud_backup/backup.py

@@ -3,6 +3,8 @@ from __future__ import annotations
 import asyncio
 import json
 import logging
+import os
+import tempfile
 from collections.abc import AsyncIterator, Callable, Coroutine
 from typing import Any
 
@@ -20,6 +22,7 @@ from .const import (
     DATA_CLIENT,
     DOMAIN,
     META_SUFFIX,
+    SPOOL_FLUSH_BYTES,
     TAR_PREFIX,
     TAR_SUFFIX,
 )
@@ -44,6 +47,50 @@ def _agentbackup_from_dict(d: dict[str, Any]) -> AgentBackup:
     return AgentBackup(**d)  # type: ignore[arg-type]
 
 
+async def _spool_stream_to_tempfile(stream: AsyncIterator[bytes]) -> tuple[str, int]:
+    """Spool an async byte stream into a temporary file and return (path, size).
+
+    This avoids chunked WebDAV uploads and improves compatibility with reverse proxies.
+    """
+    fd, path = tempfile.mkstemp(prefix="owncloud_backup_", suffix=".tar")
+    os.close(fd)
+
+    size = 0
+    buf = bytearray()
+
+    try:
+        async for chunk in stream:
+            if not chunk:
+                continue
+            buf.extend(chunk)
+            size += len(chunk)
+
+            if len(buf) >= SPOOL_FLUSH_BYTES:
+                data = bytes(buf)
+                buf.clear()
+                await asyncio.to_thread(_write_bytes_to_file, path, data, append=True)
+
+        if buf:
+            await asyncio.to_thread(_write_bytes_to_file, path, bytes(buf), append=True)
+
+        return path, size
+
+    except Exception:
+        # Ensure no leftovers on failure
+        try:
+            os.remove(path)
+        except OSError:
+            pass
+        raise
+
+
+def _write_bytes_to_file(path: str, data: bytes, *, append: bool) -> None:
+    mode = "ab" if append else "wb"
+    with open(path, mode) as f:
+        f.write(data)
+        f.flush()
+
+
 class OwnCloudBackupAgent(BackupAgent):
     """Backup agent storing backups in ownCloud via WebDAV."""
 
@@ -61,21 +108,35 @@ class OwnCloudBackupAgent(BackupAgent):
         backup: AgentBackup,
         **kwargs: Any,
     ) -> None:
-        """Upload a backup + metadata sidecar."""
+        """Upload a backup + metadata sidecar.
+
+        To avoid chunked uploads (which often break behind proxies), we spool
+        the stream to a temp file and upload with a Content-Length.
+        """
+        temp_path: str | None = None
         try:
             tar_name = _make_tar_name(backup.backup_id)
             meta_name = _make_meta_name(backup.backup_id)
 
-            # 1) Upload tar stream
+            # 1) Spool tar stream to temp file
             stream = await open_stream()
-            await self._client.put_stream(tar_name, stream)
+            temp_path, size = await _spool_stream_to_tempfile(stream)
 
-            # 2) Upload metadata JSON (small)
+            # 2) Upload tar file with Content-Length
+            await self._client.put_file(tar_name, temp_path, size)
+
+            # 3) Upload metadata JSON (small)
             meta_bytes = json.dumps(backup.to_dict(), ensure_ascii=False).encode("utf-8")
             await self._client.put_bytes(meta_name, meta_bytes)
 
         except Exception as err:  # noqa: BLE001
             raise BackupAgentError(f"Upload to ownCloud failed: {err}") from err
+        finally:
+            if temp_path:
+                try:
+                    os.remove(temp_path)
+                except OSError:
+                    pass
 
     async def async_list_backups(self, **kwargs: Any) -> list[AgentBackup]:
         """List backups by reading metadata sidecars; fallback to tar stat if missing."""
@@ -217,3 +278,4 @@ def async_register_backup_agents_listener(
         hass.data[DATA_BACKUP_AGENT_LISTENERS].remove(listener)
 
     return remove_listener
+