compat.pending_raise: allow/ignore None ex; make rethrow optional

[bup.git] / lib / bup / compat.py

diff --git a/lib/bup/compat.py b/lib/bup/compat.py
index 2cd6fbaf8a3cbb01074b325ec55be62119ac7880..9002025a6d49ec76cda219bc46468f10769ca905 100644 (file)
--- a/lib/bup/compat.py
+++ b/lib/bup/compat.py
@@ -1,6 +1,5 @@
 
 from __future__ import absolute_import, print_function
-from array import array
 from binascii import hexlify
 from traceback import print_exception
 import os, sys
@@ -13,9 +12,12 @@ py3 = py_maj >= 3
 
 if py3:
 
+    # pylint: disable=unused-import
     from os import environb as environ
     from os import fsdecode, fsencode
     from shlex import quote
+    # pylint: disable=undefined-variable
+    # (for python2 looking here)
     ModuleNotFoundError = ModuleNotFoundError
     input = input
     range = range
@@ -38,18 +40,19 @@ if py3:
         return ex
 
     class pending_raise:
-        """Rethrow either the provided ex, or any exception raised by the with
-        statement body.  (Supports Python 2 compatibility.)
+        """If rethrow is true, rethrow ex (if any), unless the body throws.
+
+        (Supports Python 2 compatibility.)
 
         """
-        def __init__(self, ex):
+        def __init__(self, ex, rethrow=True):
             self.ex = ex
+            self.rethrow = rethrow
         def __enter__(self):
             return None
         def __exit__(self, exc_type, exc_value, traceback):
-            if not exc_type:
+            if not exc_type and self.ex and self.rethrow:
                 raise self.ex
-            return None
 
     def items(x):
         return x.items()
@@ -88,13 +91,20 @@ else:  # Python 2
         return x
 
     from pipes import quote
+    # pylint: disable=unused-import
     from os import environ, getcwd
 
+    # pylint: disable=unused-import
     from bup.py2raise import reraise
 
+    # on py3 this causes errors, obviously
+    # pylint: disable=undefined-variable
     input = raw_input
+    # pylint: disable=undefined-variable
     range = xrange
+    # pylint: disable=undefined-variable
     str_type = basestring
+    # pylint: disable=undefined-variable
     int_types = (int, long)
 
     hexstr = hexlify
@@ -118,24 +128,28 @@ else:  # Python 2
         return ex
 
     class pending_raise:
-        """Rethrow either the provided ex, or any exception raised by the with
-        statement body, after making ex the __context__ of the newer
-        exception (assuming there's no existing __context__).  Ensure
-        the exceptions have __tracebacks__.  (Supports Python 2
-        compatibility.)
+        """If rethrow is true, rethrow ex (if any), unless the body throws.
+
+        If the body does throw, make any provided ex the __context__
+        of the newer exception (assuming there's no existing
+        __context__).  Ensure the exceptions have __tracebacks__.
+        (Supports Python 2 compatibility.)
 
         """
-        def __init__(self, ex):
+        def __init__(self, ex, rethrow=True):
             self.ex = ex
+            self.rethrow = rethrow
         def __enter__(self):
-            add_ex_tb(self.ex)
-            return None
+            if self.ex:
+                add_ex_tb(self.ex)
         def __exit__(self, exc_type, exc_value, traceback):
-            if not exc_type:
+            if exc_value:
+                if self.ex:
+                    add_ex_tb(exc_value)
+                    add_ex_ctx(exc_value, self.ex)
+                return
+            if self.rethrow and self.ex:
                 raise self.ex
-            add_ex_tb(exc_value)
-            add_ex_ctx(exc_value, self.ex)
-            return None
 
     def dump_traceback(ex):
         stack = [ex]
@@ -169,41 +183,27 @@ else:  # Python 2
 
     buffer = buffer
 
+try:
+    import bup_main
+except ModuleNotFoundError:
+    bup_main = None
 
-argv = None
-argvb = None
-
-def _configure_argv():
-    global argv, argvb
-    assert not argv
-    assert not argvb
-    if len(sys.argv) > 1:
-        if environ.get(b'BUP_ARGV_0'):
-            print('error: BUP_ARGV* set and sys.argv not empty', file=sys.stderr)
-            sys.exit(2)
-        argv = sys.argv
-        argvb = [argv_bytes(x) for x in argv]
-        return
-    args = []
-    i = 0
-    arg = environ.get(b'BUP_ARGV_%d' % i)
-    while arg is not None:
-        args.append(arg)
-        i += 1
-        arg = environ.get(b'BUP_ARGV_%d' % i)
-    i -= 1
-    while i >= 0:
-        del environ[b'BUP_ARGV_%d' % i]
-        i -= 1
-    argvb = args
-    # System encoding?
+if bup_main:
+    def get_argvb():
+        "Return a new list containing the current process argv bytes."
+        return bup_main.argv()
     if py3:
-        argv = [x.decode(errors='surrogateescape') for x in args]
+        def get_argv():
+            "Return a new list containing the current process argv strings."
+            return [x.decode(errors='surrogateescape') for x in bup_main.argv()]
     else:
-        argv = argvb
-
-_configure_argv()
-
+        def get_argv():
+            return bup_main.argv()
+else:
+    def get_argvb():
+        raise Exception('get_argvb requires the bup_main module');
+    def get_argv():
+        raise Exception('get_argv requires the bup_main module');
 
 def wrap_main(main):
     """Run main() and raise a SystemExit with the return value if it