[FIX] runbot: fix rmtree permission issues

When trying to garbaged collect diretories if a file or a directory
that the runbot user process own is not writable for the owner, the
garbage collecting fails.

The worst case is when both a file and its parent directory are not
writable by the user. In that case, even by changing the file
permission, the runbot cannot remove the file because of the directory
not being writable.

With this commit, a new `rmforest` function is made that tries, in case
of permission error, to change the owner permission of the file and its
parent directory to being writable before retrying to unlink them.

Author: d-fence

runbot/models/build.py

@@ -43,6 +43,30 @@
 USERUID = os.getuid()
 USERNAME = getpass.getuser()
 
+
+def rmforest(top_dir):
+    """Rewrite of rmtree that tries to handle permission errors (e.g.: when a directory that the user own is u-w)
+    :param top_dir: diretory to remove
+    :type top_dir: str or Path
+    """
+    top = Path(top_dir)
+    for root, dirs, files in top.walk(top_down=False):
+        for name in files:
+            f = root / name
+            try:
+                f.unlink()
+            except PermissionError:
+                perm = f.stat().st_mode | 0o00600
+                f.chmod(perm)
+                pperm = f.parent.stat().st_mode | 0o00700
+                f.parent.chmod(pperm)
+                f.unlink()
+        for name in dirs:
+            d = root / name
+            d.rmdir()
+    top.rmdir()
+
+
 def make_selection(array):
     return [(elem, elem.replace('_', ' ').capitalize()) if isinstance(elem, str) else elem for elem in array]
 
@@ -645,15 +669,15 @@ def filter_ids(dest_list, label):
                 for bdir_file in build_dir.iterdir():
                     if bdir_file.is_dir() and bdir_file.name not in ('logs', 'tests'):
                         try:
-                            shutil.rmtree(bdir_file)
+                            rmforest(bdir_file)
                         except Exception:
                             _logger.exception('Failed to remove %s', bdir_file)
                     elif bdir_file.name == 'logs':
                         for log_file_path in bdir_file.iterdir():
                             if log_file_path.is_dir():
 
                                 try:
-                                    shutil.rmtree(log_file_path)
+                                    rmforest(log_file_path)
                                 except Exception:
                                     _logger.exception('Failed to remove %s', log_file_path)
                             elif log_file_path.name in ('run.txt', 'wake_up.txt') or not log_file_path.name.endswith('.txt'):