[Python-checkins] cpython (3.5): Issue #20766: Fix references leaked by pdb in the handling of SIGINT handlers.

[xavier.degaye]

https://hg.python.org/cpython/rev/31a2d270c0c3
changeset:   104466:31a2d270c0c3
branch:      3.5
parent:      104449:5fa74d8c987b
user:        Xavier de Gaye <xdegaye at users.sourceforge.net>
date:        Wed Oct 12 20:13:24 2016 +0200
summary:
  Issue #20766: Fix references leaked by pdb in the handling of SIGINT handlers.

files:
  Lib/pdb.py           |  10 +++++++---
  Lib/test/test_pdb.py |  23 +++++++++++++++++++++++
  Misc/NEWS            |   3 +++
  3 files changed, 33 insertions(+), 3 deletions(-)


diff --git a/Lib/pdb.py b/Lib/pdb.py
--- a/Lib/pdb.py
+++ b/Lib/pdb.py
@@ -134,6 +134,8 @@
 
 class Pdb(bdb.Bdb, cmd.Cmd):
 
+    _previous_sigint_handler = None
+
     def __init__(self, completekey='tab', stdin=None, stdout=None, skip=None,
                  nosigint=False):
         bdb.Bdb.__init__(self, skip=skip)
@@ -187,8 +189,6 @@
         self.message("\nProgram interrupted. (Use 'cont' to resume).")
         self.set_step()
         self.set_trace(frame)
-        # restore previous signal handler
-        signal.signal(signal.SIGINT, self._previous_sigint_handler)
 
     def reset(self):
         bdb.Bdb.reset(self)
@@ -337,6 +337,10 @@
                                  (expr, newvalue, oldvalue))
 
     def interaction(self, frame, traceback):
+        # Restore the previous signal handler at the Pdb prompt.
+        if Pdb._previous_sigint_handler:
+            signal.signal(signal.SIGINT, Pdb._previous_sigint_handler)
+            Pdb._previous_sigint_handler = None
         if self.setup(frame, traceback):
             # no interaction desired at this time (happens if .pdbrc contains
             # a command like "continue")
@@ -1037,7 +1041,7 @@
         """
         if not self.nosigint:
             try:
-                self._previous_sigint_handler = \
+                Pdb._previous_sigint_handler = \
                     signal.signal(signal.SIGINT, self.sigint_handler)
             except ValueError:
                 # ValueError happens when do_continue() is invoked from
diff --git a/Lib/test/test_pdb.py b/Lib/test/test_pdb.py
--- a/Lib/test/test_pdb.py
+++ b/Lib/test/test_pdb.py
@@ -911,6 +911,29 @@
     (Pdb) continue
     """
 
+def test_pdb_issue_20766():
+    """Test for reference leaks when the SIGINT handler is set.
+
+    >>> def test_function():
+    ...     i = 1
+    ...     while i <= 2:
+    ...         sess = pdb.Pdb()
+    ...         sess.set_trace(sys._getframe())
+    ...         print('pdb %d: %s' % (i, sess._previous_sigint_handler))
+    ...         i += 1
+
+    >>> with PdbTestInput(['continue',
+    ...                    'continue']):
+    ...     test_function()
+    > <doctest test.test_pdb.test_pdb_issue_20766[0]>(6)test_function()
+    -> print('pdb %d: %s' % (i, sess._previous_sigint_handler))
+    (Pdb) continue
+    pdb 1: <built-in function default_int_handler>
+    > <doctest test.test_pdb.test_pdb_issue_20766[0]>(5)test_function()
+    -> sess.set_trace(sys._getframe())
+    (Pdb) continue
+    pdb 2: <built-in function default_int_handler>
+    """
 
 class PdbTestCase(unittest.TestCase):
 
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -107,6 +107,9 @@
 Library
 -------
 
+- Issue #20766: Fix references leaked by pdb in the handling of SIGINT
+  handlers.
+
 - Issue #26293: Fixed writing ZIP files that starts not from the start of the
   file.  Offsets in ZIP file now are relative to the start of the archive in
   conforming to the specification.

-- 
Repository URL: https://hg.python.org/cpython