From 359bcaa539d9bbb2b008b5fd0a76c758b489bed5 Mon Sep 17 00:00:00 2001
From: Guido van Rossum <guido@python.org>
Date: Fri, 14 Nov 1997 22:24:28 +0000
Subject: [PATCH] This fix (across 4 files in 3 directories) solves a subtle
 problem with signal handlers in a fork()ed child process when Python is
 compiled with thread support.  The bug was reported by Scott
 <scott@chronis.icgroup.com>.

What happens is that after a fork(), the variables used by the signal
module to determine whether this is the main thread or not are bogus,
and it decides that no thread is the main thread, so no signals will
be delivered.

The solution is the addition of PyOS_AfterFork(), which fixes the signal
module's variables.  A dummy version of the function is present in the
intrcheck.c source file which is linked when the signal module is not
used.
---
 Include/intrcheck.h    | 1 +
 Modules/posixmodule.c  | 1 +
 Modules/signalmodule.c | 9 +++++++++
 Parser/intrcheck.c     | 5 +++++
 4 files changed, 16 insertions(+)

diff --git a/Include/intrcheck.h b/Include/intrcheck.h
index f9658e28b14..85660516900 100644
--- a/Include/intrcheck.h
+++ b/Include/intrcheck.h
@@ -37,6 +37,7 @@ PERFORMANCE OF THIS SOFTWARE.
 
 extern int PyOS_InterruptOccurred Py_PROTO((void));
 extern void PyOS_InitInterrupts Py_PROTO((void));
+void PyOS_AfterFork Py_PROTO((void));
 
 #ifdef __cplusplus
 }
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index e06827aa720..58111efda5e 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -1082,6 +1082,7 @@ posix_fork(self, args)
 	pid = fork();
 	if (pid == -1)
 		return posix_error();
+	PyOS_AfterFork();
 	return PyInt_FromLong((long)pid);
 }
 #endif
diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
index e8154925278..e91c3cb6f60 100644
--- a/Modules/signalmodule.c
+++ b/Modules/signalmodule.c
@@ -613,3 +613,12 @@ PyOS_InterruptOccurred()
 	}
 	return 0;
 }
+
+void
+PyOS_AfterFork()
+{
+#ifdef WITH_THREAD
+	main_thread = get_thread_ident();
+	main_pid = getpid();
+#endif
+}
diff --git a/Parser/intrcheck.c b/Parser/intrcheck.c
index a2a31452bb4..7fe6205f444 100644
--- a/Parser/intrcheck.c
+++ b/Parser/intrcheck.c
@@ -219,3 +219,8 @@ PyOS_InterruptOccurred()
 }
 
 #endif /* !OK */
+
+void
+PyOS_AfterFork()
+{
+}