[src/trunk]: src/lib/libc/include Add an explanation of how namespace.h works.

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/e969adda6873
branches:  trunk
changeset: 356947:e969adda6873
user:      christos <christos%NetBSD.org@localhost>
date:      Sun Oct 22 00:20:50 2017 +0000

description:
Add an explanation of how namespace.h works.

diffstat:

 lib/libc/include/namespace.h |  12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)

diffs (26 lines):

diff -r 1c7621bcf49f -r e969adda6873 lib/libc/include/namespace.h
--- a/lib/libc/include/namespace.h      Sat Oct 21 23:49:28 2017 +0000
+++ b/lib/libc/include/namespace.h      Sun Oct 22 00:20:50 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: namespace.h,v 1.186 2017/02/08 17:30:27 maya Exp $     */
+/*     $NetBSD: namespace.h,v 1.187 2017/10/22 00:20:50 christos Exp $ */
 
 /*-
  * Copyright (c) 1997-2004 The NetBSD Foundation, Inc.
@@ -96,6 +96,16 @@
 #define warnc          _warnc
 #define warnx          _warnx
 
+/*
+ * namespace protection for libc functions that are used internally
+ * in libc and should be not overriden by applications. To do this,
+ * this header renames them to a name that starts with an "_" so that
+ * libc uses the "_" flavor internally (and this name is not part of
+ * the application namespace), and then a weak alias is added to the
+ * "_" name next to the function definition so that the function is
+ * exposed again.
+ */
+
 #ifdef __weak_alias
 #define MD2Data                        _MD2Data
 #define MD2End                 _MD2End