From: Ulrich Drepper <drepper@redhat.com>
Date: Fri, 8 Aug 1997 00:34:55 +0000 (+0000)
Subject: (__libc_once, __libc_once_define): New macros.
X-Git-Tag: cvs/glibc-2_0_5pre2~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=181e1431e49988869b003be6c562893a13741cf6;p=thirdparty%2Fglibc.git

(__libc_once, __libc_once_define): New macros.
---

diff --git a/sysdeps/mach/libc-lock.h b/sysdeps/mach/libc-lock.h
index cfd176750a5..0b80b1ca513 100644
--- a/sysdeps/mach/libc-lock.h
+++ b/sysdeps/mach/libc-lock.h
@@ -72,6 +72,20 @@ typedef struct __libc_lock_opaque__ __libc_lock_t;
     (*__save_FCT)(__save_ARG);						    \
 }
 
+/* Use mutexes as once control variables. */
+
+/* Define once control variable.  */
+#define __libc_once_define(CLASS, NAME) \
+  CLASS __libc_lock_define_initialized(,NAME)
+
+/* Call handler iff the first call.  */
+#define __libc_once(ONCE_CONTROL, INIT_FUNCTION) \
+  do {									      \
+    if (!__libc_lock_trylock(ONCE_CONTROL) {				      \
+      (INIT_FUNCTION) ();						      \
+      __libc_lock_lock(ONCE_CONTROL);					      \
+    }									      \
+  } while (0)
 
 #ifdef _LIBC
 /* We need portable names for some functions.  E.g., when they are