resume interrupted downloads #968 #793 (#1217)

Author: AndreyNikiforov

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+- feat: resume interrupted downloads [#968](https://github.com/icloud-photos-downloader/icloud_photos_downloader/issues/968) [#793](https://github.com/icloud-photos-downloader/icloud_photos_downloader/issues/793)
 - feat: add `--skip-photos` filter [#401](https://github.com/icloud-photos-downloader/icloud_photos_downloader/issues/401) [#1206](https://github.com/icloud-photos-downloader/icloud_photos_downloader/issues/1206)
 
 ## 1.29.4 (2025-08-12)

src/icloudpd/download.py

@@ -1,9 +1,11 @@
 """Handles file downloads with retries and error handling"""
 
+import base64
 import datetime
 import logging
 import os
 import time
+from functools import partial
 
 from requests import Response
 from tzlocal import get_localzone
@@ -68,11 +70,14 @@ def mkdirs_for_path_dry_run(logger: logging.Logger, download_path: str) -> bool:
 
 
 def download_response_to_path(
-    _logger: logging.Logger, response: Response, download_path: str, created_date: datetime.datetime
+    response: Response,
+    temp_download_path: str,
+    append_mode: bool,
+    download_path: str,
+    created_date: datetime.datetime,
 ) -> bool:
     """Saves response content into file with desired created date"""
-    temp_download_path = download_path + ".part"
-    with open(temp_download_path, "wb") as file_obj:
+    with open(temp_download_path, ("ab" if append_mode else "wb")) as file_obj:
         for chunk in response.iter_content(chunk_size=1024):
             if chunk:
                 file_obj.write(chunk)
@@ -84,6 +89,8 @@ def download_response_to_path(
 def download_response_to_path_dry_run(
     logger: logging.Logger,
     _response: Response,
+    _temp_download_path: str,
+    _append_mode: bool,
     download_path: str,
     _created_date: datetime.datetime,
 ) -> bool:
@@ -107,22 +114,36 @@ def download_media(
     """Download the photo to path, with retries and error handling"""
 
     mkdirs_local = mkdirs_for_path_dry_run if dry_run else mkdirs_for_path
-    download_local = download_response_to_path_dry_run if dry_run else download_response_to_path
-
     if not mkdirs_local(logger, download_path):
         return False
 
+    checksum = base64.b64decode(version.checksum)
+    checksum32 = base64.b32encode(checksum).decode()
+    download_dir = os.path.dirname(download_path)
+    temp_download_path = os.path.join(download_dir, checksum32) + ".part"
+
+    download_local = (
+        partial(download_response_to_path_dry_run, logger) if dry_run else download_response_to_path
+    )
+
     retries = 0
     while True:
         try:
-            photo_response = photo.download(version.url)
-            if photo_response:
-                return download_local(logger, photo_response, download_path, photo.created)
-
-            logger.error(
-                "Could not find URL to download %s for size %s", version.filename, size.value
-            )
-            break
+            append_mode = os.path.exists(temp_download_path)
+            current_size = os.path.getsize(temp_download_path) if append_mode else 0
+            if append_mode:
+                logger.debug(f"Resuming downloading of {download_path} from {current_size}")
+
+            photo_response = photo.download(version.url, current_size)
+            if photo_response.ok:
+                return download_local(
+                    photo_response, temp_download_path, append_mode, download_path, photo.created
+                )
+            else:
+                logger.error(
+                    "Could not find URL to download %s for size %s", version.filename, size.value
+                )
+                break
 
         except PyiCloudAPIResponseException as ex:
             if "Invalid global session" in str(ex):

src/pyicloud_ipd/asset_version.py

@@ -2,11 +2,12 @@
 
 
 class AssetVersion:
-    def __init__(self, filename: str, size: int, url: str, type: str) -> None:
+    def __init__(self, filename: str, size: int, url: str, type: str, checksum: str) -> None:
         self.filename = filename
         self.size = size
         self.url = url
         self.type = type
+        self.checksum = checksum
 
     def __eq__(self, other: object) -> bool: 
         if not isinstance(other, AssetVersion):

src/pyicloud_ipd/services/photos.py

@@ -788,6 +788,7 @@ def versions(self) -> Dict[VersionSize, AssetVersion]:
                     if size_entry:
                         version['size'] = size_entry['value']['size']
                         version['url'] = size_entry['value']['downloadURL']
+                        version['checksum'] = size_entry['value']['fileChecksum']
                     else:
                         raise ValueError(f"Expected {prefix}Res, but missing it")
                         # version['size'] = None
@@ -814,7 +815,7 @@ def versions(self) -> Dict[VersionSize, AssetVersion]:
                         _size_suffix = self.VERSION_FILENAME_SUFFIX_LOOKUP[key]
                         version["filename"] = add_suffix_to_filename(f"-{_size_suffix}", version["filename"])
 
-                    _versions[key] = AssetVersion(version["filename"], version['size'], version['url'], version['type'])
+                    _versions[key] = AssetVersion(version["filename"], version['size'], version['url'], version['type'], version['checksum'])
 
             # swap original & alternative according to swap_raw_policy
             if AssetVersionSize.ALTERNATIVE in _versions and (("raw" in _versions[AssetVersionSize.ALTERNATIVE].type and self._service.raw_policy == RawTreatmentPolicy.AS_ORIGINAL) or ("raw" in _versions[AssetVersionSize.ORIGINAL].type and self._service.raw_policy == RawTreatmentPolicy.AS_ALTERNATIVE)):
@@ -827,9 +828,13 @@ def versions(self) -> Dict[VersionSize, AssetVersion]:
 
         return self._versions
 
-    def download(self, url: str) -> Response:
+    def download(self, url: str, start:int = 0) -> Response:
+        headers = {
+            "Range": f"bytes={start}-"
+        }
         return self._service.session.get(
             url,
+            headers=headers,
             stream=True
         )