X-Git-Url: https://arthur.barton.de/gitweb/?a=blobdiff_plain;f=lib%2Fbup%2Fcompat.py;h=00575036e27cc46f7fb6b3408e273831526b9daa;hb=4448f184253125e1b8bd0c55d0098a335d15b90b;hp=9002025a6d49ec76cda219bc46468f10769ca905;hpb=ca1b82ee3ab053c50fc7c1fc491928c5c2c8fc19;p=bup.git

diff --git a/lib/bup/compat.py b/lib/bup/compat.py
index 9002025..0057503 100644
--- a/lib/bup/compat.py
+++ b/lib/bup/compat.py
@@ -13,6 +13,7 @@ py3 = py_maj >= 3
 if py3:
 
     # pylint: disable=unused-import
+    from contextlib import ExitStack, nullcontext
     from os import environb as environ
     from os import fsdecode, fsencode
     from shlex import quote
@@ -46,13 +47,17 @@ if py3:
 
         """
         def __init__(self, ex, rethrow=True):
+            self.closed = False
             self.ex = ex
             self.rethrow = rethrow
         def __enter__(self):
             return None
         def __exit__(self, exc_type, exc_value, traceback):
+            self.closed = True
             if not exc_type and self.ex and self.rethrow:
                 raise self.ex
+        def __del__(self):
+            assert self.closed
 
     def items(x):
         return x.items()
@@ -82,6 +87,8 @@ if py3:
 
 else:  # Python 2
 
+    from contextlib import contextmanager
+
     ModuleNotFoundError = ImportError
 
     def fsdecode(x):
@@ -97,6 +104,10 @@ else:  # Python 2
     # pylint: disable=unused-import
     from bup.py2raise import reraise
 
+    @contextmanager
+    def nullcontext(enter_result=None):
+        yield enter_result
+
     # on py3 this causes errors, obviously
     # pylint: disable=undefined-variable
     input = raw_input
@@ -137,12 +148,14 @@ else:  # Python 2
 
         """
         def __init__(self, ex, rethrow=True):
+            self.closed = False
             self.ex = ex
             self.rethrow = rethrow
         def __enter__(self):
             if self.ex:
                 add_ex_tb(self.ex)
         def __exit__(self, exc_type, exc_value, traceback):
+            self.closed = True
             if exc_value:
                 if self.ex:
                     add_ex_tb(exc_value)
@@ -150,6 +163,8 @@ else:  # Python 2
                 return
             if self.rethrow and self.ex:
                 raise self.ex
+        def __del__(self):
+            assert self.closed
 
     def dump_traceback(ex):
         stack = [ex]
@@ -167,6 +182,31 @@ else:  # Python 2
             tb = getattr(ex, '__traceback__', None)
             print_exception(type(ex), ex, tb)
 
+    class ExitStack:
+        def __init__(self):
+            self.contexts = []
+
+        def __enter__(self):
+            return self
+
+        def __exit__(self, value_type, value, traceback):
+            init_value = value
+            for ctx in reversed(self.contexts):
+                try:
+                    ctx.__exit__(value_type, value, traceback)
+                except BaseException as ex:
+                    add_ex_tb(ex)
+                    if value:
+                        add_ex_ctx(ex, value)
+                    value_type = type(ex)
+                    value = ex
+                    traceback = ex.__traceback__
+            if value is not init_value:
+                raise value
+
+        def enter_context(self, x):
+            self.contexts.append(x)
+
     def items(x):
         return x.iteritems()