From bd5637af6d4a5f318bedf9912b931b9338f89c1a Mon Sep 17 00:00:00 2001
From: David Chisnall <theraven@FreeBSD.org>
Date: Sat, 30 Mar 2019 10:48:30 +0000
Subject: [PATCH] Fix memory leak in @synchronized.

This was actually a memory leak in the hidden class implementation, but
it was mostly visible in the @synchronized implementation.  Every hidden
class registered a custom .cxx_destruct method, to handle cleanup of all
of the hidden class structures.  Unfortunately, this destructor failed
to delete the reflection metadata structures associated with the class,
specifically the objc_method_list containing the objc_method pointing to
the destructor itself.

Fixes #98
---
 associate.m | 3 +++
 class.h     | 9 +++++++++
 runtime.c   | 4 ++--
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/associate.m b/associate.m
index cf8865d..a342475 100644
--- a/associate.m
+++ b/associate.m
@@ -275,6 +275,9 @@ static void deallocHiddenClass(id obj, SEL _cmd)
 		}
 	}
 	obj->isa = hiddenClass->super_class;
+	// Free the introspection structures:
+	freeMethodLists(hiddenClass);
+	freeIvarLists(hiddenClass);
 	// Free the class
 	free(hiddenClass);
 }
diff --git a/class.h b/class.h
index d2e947c..44ed65f 100644
--- a/class.h
+++ b/class.h
@@ -434,4 +434,13 @@ static inline BOOL classIsOrInherits(Class cls, Class base)
 	return NO;
 }
 
+/**
+ * Free the instance variable lists associated with a class.
+ */
+void freeIvarLists(Class aClass);
+/**
+ * Free the method lists associated with a class.
+ */
+void freeMethodLists(Class aClass);
+
 #endif //__OBJC_CLASS_H_INCLUDED
diff --git a/runtime.c b/runtime.c
index 1b6f126..245ef03 100644
--- a/runtime.c
+++ b/runtime.c
@@ -622,7 +622,7 @@ id objc_getRequiredClass(const char *name)
 	return cls;
 }
 
-static void freeMethodLists(Class aClass)
+PRIVATE void freeMethodLists(Class aClass)
 {
 	struct objc_method_list *methods = aClass->methods;
 	while(methods != NULL)
@@ -637,7 +637,7 @@ static void freeMethodLists(Class aClass)
 	}
 }
 
-static void freeIvarLists(Class aClass)
+PRIVATE void freeIvarLists(Class aClass)
 {
 	struct objc_ivar_list *ivarlist = aClass->ivars;
 	if (NULL == ivarlist) { return; }