From: Guido van Rossum <guido@python.org>
Date: Fri, 14 Nov 1997 22:24:28 +0000 (+0000)
Subject: This fix (across 4 files in 3 directories) solves a subtle problem with
X-Git-Tag: v1.5b1~103
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=359bcaa539d9bbb2b008b5fd0a76c758b489bed5;p=thirdparty%2FPython%2Fcpython.git

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.
---

diff --git a/Include/intrcheck.h b/Include/intrcheck.h
index f9658e28b146..85660516900e 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 e06827aa720d..58111efda5eb 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 e8154925278b..e91c3cb6f605 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 a2a31452bb42..7fe6205f444b 100644
--- a/Parser/intrcheck.c
+++ b/Parser/intrcheck.c
@@ -219,3 +219,8 @@ PyOS_InterruptOccurred()
 }
 
 #endif /* !OK */
+
+void
+PyOS_AfterFork()
+{
+}