From 37040cdace1982772e5f35e4acfa13861d72065d Mon Sep 17 00:00:00 2001
From: Jesse Noller <jnoller@gmail.com>
Date: Tue, 30 Sep 2008 00:15:45 +0000
Subject: [PATCH] issue3770: if SEM_OPEN is 0, disable the mp.synchronize
 module, rev. Nick Coghlan, Damien Miller

---
 Doc/library/multiprocessing.rst    |  7 +++++++
 Lib/multiprocessing/synchronize.py | 11 +++++++++++
 Lib/test/regrtest.py               |  3 +++
 Lib/test/test_multiprocessing.py   |  8 ++++++++
 setup.py                           |  8 ++++++++
 5 files changed, 37 insertions(+)

diff --git a/Doc/library/multiprocessing.rst b/Doc/library/multiprocessing.rst
index 42d76a3ed83..a005dc40119 100644
--- a/Doc/library/multiprocessing.rst
+++ b/Doc/library/multiprocessing.rst
@@ -18,6 +18,13 @@ to this, the :mod:`multiprocessing` module allows the programmer to fully
 leverage multiple processors on a given machine.  It runs on both Unix and
 Windows.
 
+.. warning::
+
+    This package largely requires a functioning shared semaphore
+    implementation on the host operating system to function. Without one, the 
+    :mod:`multiprocessing.synchronize` module will be disabled, and attempts to 
+    import it will result in an ImportError. See 
+    http://bugs.python.org/issue3770 for additional information.
 
 The :class:`Process` class
 ~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/Lib/multiprocessing/synchronize.py b/Lib/multiprocessing/synchronize.py
index 428656a5b15..dacf45acca7 100644
--- a/Lib/multiprocessing/synchronize.py
+++ b/Lib/multiprocessing/synchronize.py
@@ -21,6 +21,17 @@ from multiprocessing.process import current_process
 from multiprocessing.util import Finalize, register_after_fork, debug
 from multiprocessing.forking import assert_spawning, Popen
 
+# Try to import the mp.synchronize module cleanly, if it fails
+# raise ImportError for platforms lacking a working sem_open implementation.
+# See issue 3770
+try:
+    from _multiprocessing import SemLock
+except (ImportError):
+    raise ImportError("This platform lacks a functioning sem_open" +
+                      " implementation, therefore, the required" +
+                      " synchronization primitives needed will not" +
+                      " function, see issue 3770.")
+
 #
 # Constants
 #
diff --git a/Lib/test/regrtest.py b/Lib/test/regrtest.py
index f185111fc36..996395bb8e3 100755
--- a/Lib/test/regrtest.py
+++ b/Lib/test/regrtest.py
@@ -1047,6 +1047,7 @@ _expectations = {
         test_tcl
         test_timeout
         test_urllibnet
+        test_multiprocessing
         """,
     'aix5':
         """
@@ -1077,6 +1078,7 @@ _expectations = {
         test_ossaudiodev
         test_pep277
         test_tcl
+        test_multiprocessing
         """,
     'netbsd3':
         """
@@ -1092,6 +1094,7 @@ _expectations = {
         test_ossaudiodev
         test_pep277
         test_tcl
+        test_multiprocessing
         """,
 }
 _expectations['freebsd5'] = _expectations['freebsd4']
diff --git a/Lib/test/test_multiprocessing.py b/Lib/test/test_multiprocessing.py
index 214a420708b..b0746e9f3b5 100644
--- a/Lib/test/test_multiprocessing.py
+++ b/Lib/test/test_multiprocessing.py
@@ -18,6 +18,14 @@ import socket
 import random
 import logging
 
+
+# Work around broken sem_open implementations
+try:
+    import multiprocessing.synchronize
+except ImportError, e:
+    from test.test_support import TestSkipped
+    raise TestSkipped(e)
+
 import multiprocessing.dummy
 import multiprocessing.connection
 import multiprocessing.managers
diff --git a/setup.py b/setup.py
index f979a291438..4b2318658c6 100644
--- a/setup.py
+++ b/setup.py
@@ -1269,6 +1269,14 @@ class PyBuildExt(build_ext):
                 )
             libraries = []
 
+        elif platform.startswith('openbsd'):
+            macros = dict(                  # OpenBSD
+                HAVE_SEM_OPEN=0,            # Not implemented
+                HAVE_SEM_TIMEDWAIT=0,
+                HAVE_FD_TRANSFER=1,
+                )
+            libraries = []
+
         else:                                   # Linux and other unices
             macros = dict(
                 HAVE_SEM_OPEN=1,