Add an internal _once() method. This works identical to pthread_once(3)

with the additional property that it is safe for routines in libc to use
in both single-threaded and multi-threaded processes.  Multi-threaded
processes use the pthread_once() implementation from the threading library
while single-threaded processes use a simplified "stub" version internal
to libc.  The libc stub-version of pthread_once() now also uses the
simplified "stub" version as well instead of being a nop.

Reviewed by:	deischen, Matthew Fleming @ Isilon
Suggested by:	alc
MFC after:	1 week

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/libc/include/libc_private.h b/lib/libc/include/libc_private.h
index 50903f3..bcf2b1c 100644
--- a/lib/libc/include/libc_private.h
+++ b/lib/libc/include/libc_private.h
@@ -34,6 +34,7 @@
 
 #ifndef _LIBC_PRIVATE_H_
 #define _LIBC_PRIVATE_H_
+#include <sys/_pthreadtypes.h>
 
 /*
  * This global flag is non-zero when a process has created one
@@ -147,6 +148,13 @@ int _yp_check(char **);
 void _init_tls(void);
 
 /*
+ * Provides pthread_once()-like functionality for both single-threaded
+ * and multi-threaded applications.
+ */
+int _once(pthread_once_t *, void (*)(void));
+int _libc_once(pthread_once_t *, void (*)(void));
+
+/*
  * Set the TLS thread pointer
  */
 void _set_tp(void *tp);