Exception handling for file permissions and file not found events

ia_downloader.py

@@ -133,8 +133,18 @@ def bytes_filesize_to_readable_str(bytes_filesize: int) -> str:
 
 def file_paths_in_folder(folder_path: str) -> typing.List[str]:
     """Return sorted list of paths of files at a directory (and its subdirectories)"""
+    log = logging.getLogger(__name__)
+
+    def walk_error(os_error: OSError) -> None:
+        """Log any errors occurring during os.walk"""
+        log.warning(
+            "'%s' could not be accessed during folder scanning - any contents will not be"
+            " processed. Try running script as admin",
+            os_error.filename,
+        )
+
     file_paths = []
-    for root, _, file_names in os.walk(folder_path):
+    for root, _, file_names in os.walk(folder_path, onerror=walk_error):
         for name in file_names:
             file_paths.append(os.path.join(root, name))
     return sorted(file_paths)
@@ -172,6 +182,7 @@ def get_metadata_from_files_in_folder(
     relative_paths_from_ia_metadata: typing.Optional[typing.List[str]] = None,
 ) -> typing.Dict[str, str]:
     """Return dict of file paths and metadata of files at a directory (and its subdirectories)"""
+    log = logging.getLogger(__name__)
     results = {}  # type: typing.Dict[str, str]
     if relative_paths_from_ia_metadata is not None:
         file_paths = [
@@ -182,17 +193,33 @@ def get_metadata_from_files_in_folder(
         file_paths = file_paths_in_folder(folder_path)
     if hash_flag:
         for file_path in tqdm.tqdm(file_paths):
-            if os.path.isfile(file_path):
-                md5 = md5_hash_file(file_path)
-                results[
-                    os.path.normpath(os.path.relpath(file_path, folder_path))
-                ] = md5.lower().strip()
+            if os.path.isfile(file_path):  # We will alert on this elsewhere if the file isn't found
+                try:
+                    md5 = md5_hash_file(file_path)
+                    results[
+                        os.path.normpath(os.path.relpath(file_path, folder_path))
+                    ] = md5.lower().strip()
+                except (PermissionError, OSError):
+                    log.warning(
+                        "PermissionError/OSError occurred when accessing file '%s' - try running "
+                        "script as admin",
+                        file_path,
+                    )
     else:
         # Return file sizes if we're not checking hash values
         for file_path in file_paths:
-            if os.path.isfile(file_path):
-                file_size = os.path.getsize(file_path)
-                results[os.path.normpath(os.path.relpath(file_path, folder_path))] = str(file_size)
+            if os.path.isfile(file_path):  # We will alert on this elsewhere if the file isn't found
+                try:
+                    file_size = os.path.getsize(file_path)
+                    results[os.path.normpath(os.path.relpath(file_path, folder_path))] = str(
+                        file_size
+                    )
+                except (PermissionError, OSError):
+                    log.warning(
+                        "PermissionError/OSError occurred when accessing file '%s' - try running "
+                        "script as admin",
+                        file_path,
+                    )
     return results
 
 
@@ -222,7 +249,22 @@ def check_hash(file_path: str, md5_value_from_ia: str) -> typing.Tuple[str, str]
     hash check of a file
 
     """
-    md5_value_local = md5_hash_file(file_path)
+    try:
+        md5_value_local = md5_hash_file(file_path)
+    except FileNotFoundError:
+        return (
+            "warning",
+            "'{}' file seems to have been deleted before hashing could complete".format(
+                os.path.basename(file_path)
+            ),
+        )
+    except (PermissionError, OSError):
+        return (
+            "warning",
+            "PermissionError/OSError when attempting to hash '{}'".format(
+                os.path.basename(file_path)
+            ),
+        )
     if md5_value_local.lower().strip() == md5_value_from_ia.lower().strip():
         return (
             "debug",