Re: [PATCH 17/20] unlocked stdio extensions

[Yaakov Selkowitz <yselkowi at redhat dot com>]

Index: libc/stdio/getwchar.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/getwchar.c,v
retrieving revision 1.2
diff -u -p -r1.2 getwchar.c
--- libc/stdio/getwchar.c	12 Dec 2008 17:21:08 -0000	1.2
+++ libc/stdio/getwchar.c	17 Dec 2014 18:28:02 -0000
@@ -26,34 +26,65 @@
 
 /*
 FUNCTION
-<<getwchar>>---read a wide character from standard input
+<<getwchar>>, <<getwchar_unlocked>>---read a wide character from standard input
 
 INDEX
 	getwchar
 INDEX
+	getwchar_unlocked
+INDEX
 	_getwchar_r
+INDEX
+	_getwchar_unlocked_r
 
 ANSI_SYNOPSIS
 	#include <wchar.h>
 	wint_t getwchar(void);
 
+	#define _GNU_SOURCE
+	#include <wchar.h>
+	wint_t getwchar_unlocked(void);
+
+	#include <wchar.h>
 	wint_t _getwchar_r(struct _reent *<[reent]>);
 
+	#include <wchar.h>
+	wint_t _getwchar_unlocked_r(struct _reent *<[reent]>);
+
 TRAD_SYNOPSIS
 	#include <wchar.h>
 	wint_t getwchar();
 
+	#define _GNU_SOURCE
+	#include <wchar.h>
+	wint_t getwchar_unlocked();
+
+	#include <wchar.h>
 	wint_t _getwchar_r(<[reent]>)
 	char * <[reent]>;
 
+	#include <wchar.h>
+	wint_t _getwchar_unlocked_r(<[reent]>)
+	char * <[reent]>;
+
 DESCRIPTION
 <<getwchar>> function or macro is the wide character equivalent of
 the <<getchar>> function.  You can use <<getwchar>> to get the next
 wide character from the standard input stream.  As a side effect,
 <<getwchar>> advances the standard input's current position indicator.
 
-The alternate function <<_getwchar_r>> is a reentrant version.  The
-extra argument <[reent]> is a pointer to a reentrancy structure.
+<<getwchar_unlocked>> is a non-thread-safe version of <<getwchar>>.
+<<getwchar_unlocked>> may only safely be used within a scope
+protected by flockfile() (or ftrylockfile()) and funlockfile().  This
+function may safely be used in a multi-threaded program if and only
+if they are called while the invoking thread owns the (FILE *)
+object, as is the case after a successful call to the flockfile() or
+ftrylockfile() functions.  If threads are disabled, then
+<<getwchar_unlocked>> is equivalent to <<getwchar>>.
+
+The alternate functions <<_getwchar_r>> and <<_getwchar_unlocked_r> are
+reentrant versions of the above.  The extra argument <[reent]> is a pointer to
+a reentrancy structure.
 
 RETURNS
 The next wide character cast to <<wint_t>>, unless there is no more
@@ -64,7 +95,9 @@ You can distinguish the two situations t
 using `<<ferror(stdin)>>' and `<<feof(stdin)>>'.
 
 PORTABILITY
-C99
+<<getwchar>> is required by C99.
+
+<<getwchar_unlocked>> is a GNU extension.
 */
 
 #include <_ansi.h>
Index: libc/stdio/getwchar_u.c
===================================================================
RCS file: libc/stdio/getwchar_u.c
diff -N libc/stdio/getwchar_u.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ libc/stdio/getwchar_u.c	17 Dec 2014 18:28:02 -0000
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2014 Red Hat, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <_ansi.h>
+#include <reent.h>
+#include <stdio.h>
+#include <wchar.h>
+#include "local.h"
+
+#undef getwchar_unlocked
+
+wint_t
+_DEFUN (_getwchar_unlocked_r, (ptr),
+	struct _reent *ptr)
+{
+  return _fgetwc_unlocked_r (ptr, stdin);
+}
+
+/*
+ * Synonym for fgetwc_unlocked(stdin).
+ */
+wint_t
+_DEFUN_VOID (getwchar_unlocked)
+{
+  _REENT_SMALL_CHECK_INIT (_REENT);
+  return fgetwc_unlocked (stdin);
+}