2 files changed, 66 insertions, 2 deletions
diff --git a/Objective-C/libobjcl.h b/Objective-C/libobjcl.h
index 270af45..afe9f56 100644
--- a/Objective-C/libobjcl.h
+++ b/Objective-C/libobjcl.h
@@ -43,6 +43,18 @@ typedef Ivar IVAR_T;
 typedef struct objc_ivar *IVAR_T;
 #endif
 
+#ifdef HAVE_SYS_SEM_H
+#include <sys/sem.h>
+/* According to the Single Unix Specification, Version 3, the semun
+   union type must be defined by the application writer as follows: */
+union semun
+{
+  int              val;    /* Value for SETVAL */
+  struct semid_ds *buf;    /* Buffer for IPC_STAT, IPC_SET */
+  unsigned short  *array;  /* Array for GETALL, SETALL */
+};
+#endif
+
 extern NSException *objcl_oom_exception;
 extern id objcl_current_exception;
 extern void *objcl_current_exception_lock;
@@ -159,3 +171,6 @@ objcl_acquire_lock (void *lock);
 
 void
 objcl_release_lock (void *lock);
+
+void
+objcl_initialise_lock (void **lock);
diff --git a/Objective-C/libobjcl.m b/Objective-C/libobjcl.m
index 3cbf3e5..3242fcf 100644
--- a/Objective-C/libobjcl.m
+++ b/Objective-C/libobjcl.m
@@ -65,6 +65,8 @@ objcl_initialise_runtime (void)
 #ifdef __NEXT_RUNTIME__
   PyObjC_SetupRuntimeCompat ();
 #endif
+
+  objcl_initialise_lock (&objcl_current_exception_lock);
 }
 
 
@@ -559,14 +561,61 @@ objcl_create_imp (IMP callback,
 
 
 void
+objcl_initialise_lock (void **lock)
+{
+#ifdef HAVE_SYS_SEM_H
+  int sem;
+  union semun initop;
+
+  sem = semget (IPC_PRIVATE, 1, IPC_CREAT | 0600);
+  *lock = malloc (sizeof (int));
+  *((int *) *lock) = sem;
+
+  initop.val = 1;
+  semctl (sem, 0, SETVAL, initop);
+#else
+#warning "I do not know how to do locking on this platform."
+#endif
+}
+
+
+void
 objcl_acquire_lock (void *lock)
 {
-#warning "FIXME"
+#ifdef HAVE_SYS_SEM_H
+  struct sembuf op;
+  op.sem_num = 0; op.sem_op = +1; op.sem_flg = 0;
+
+  if ((semop (*((int *) lock), &op, 1)) < 0)
+    {
+      [[NSException exceptionWithName: @"MLKLockLossage"
+                    reason: @"Acquiring the exception lock failed (don't ask me why)."
+                    userInfo: nil] raise];
+    }
+
+  TRACE (@"Exception buffer locked.");
+#else
+#warning "I do not know how to do locking on this platform."
+#endif
 }
 
 
 void
 objcl_release_lock (void *lock)
 {
-#warning "FIXME"
+#ifdef HAVE_SYS_SEM_H
+  struct sembuf op;
+  op.sem_num = 0; op.sem_op = +1; op.sem_flg = 0;
+
+  if ((semop (*((int *) lock), &op, 1)) < 0)
+    {
+      [[NSException exceptionWithName: @"MLKLockLossage"
+                    reason: @"Acquiring the exception lock failed (don't ask me why)."
+                    userInfo: nil] raise];
+    }
+
+  TRACE (@"Exception buffer unlocked.");
+#else
+#warning "I do not know how to do locking on this platform."
+#endif
 }