Re: [PATCH 07/20] unlocked stdio extensions

[Yaakov Selkowitz <yselkowi at redhat dot com>]

Index: libc/stdio/fgetwc.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/fgetwc.c,v
retrieving revision 1.6
diff -u -p -r1.6 fgetwc.c
--- libc/stdio/fgetwc.c	29 Apr 2013 21:06:23 -0000	1.6
+++ libc/stdio/fgetwc.c	17 Dec 2014 18:26:55 -0000
@@ -26,40 +26,72 @@
 
 /*
 FUNCTION
-<<fgetwc>>, <<getwc>>---get a wide character from a file or stream
+<<fgetwc>>, <<getwc>>, <<fgetwc_unlocked>>, <<getwc_unlocked>>---get a wide character from a file or stream
 
 INDEX
 	fgetwc
 INDEX
+	fgetwc_unlocked
+INDEX
 	_fgetwc_r
 INDEX
+	_fgetwc_unlocked_r
+INDEX
 	getwc
 INDEX
+	getwc_unlocked
+INDEX
 	_getwc_r
+INDEX
+	_getwc_unlocked_r
 
 ANSI_SYNOPSIS
 	#include <stdio.h>
 	#include <wchar.h>
 	wint_t fgetwc(FILE *<[fp]>);
 
+	#define _GNU_SOURCE
+	#include <stdio.h>
+	#include <wchar.h>
+	wint_t fgetwc_unlocked(FILE *<[fp]>);
+
 	#include <stdio.h>
 	#include <wchar.h>
 	wint_t _fgetwc_r(struct _reent *<[ptr]>, FILE *<[fp]>);
 
 	#include <stdio.h>
 	#include <wchar.h>
+	wint_t _fgetwc_unlocked_r(struct _reent *<[ptr]>, FILE *<[fp]>);
+
+	#include <stdio.h>
+	#include <wchar.h>
 	wint_t getwc(FILE *<[fp]>);
 
+	#define _GNU_SOURCE
+	#include <stdio.h>
+	#include <wchar.h>
+	wint_t getwc_unlocked(FILE *<[fp]>);
+
 	#include <stdio.h>
 	#include <wchar.h>
 	wint_t _getwc_r(struct _reent *<[ptr]>, FILE *<[fp]>);
 
+	#include <stdio.h>
+	#include <wchar.h>
+	wint_t _getwc_unlocked_r(struct _reent *<[ptr]>, FILE *<[fp]>);
+
 TRAD_SYNOPSIS
 	#include <stdio.h>
 	#include <wchar.h>
 	wint_t fgetwc(<[fp]>)
 	FILE *<[fp]>;
 
+	#define _GNU_SOURCE
+	#include <stdio.h>
+	#include <wchar.h>
+	wint_t fgetwc_unlocked(<[fp]>)
+	FILE *<[fp]>;
+
 	#include <stdio.h>
 	#include <wchar.h>
 	wint_t _fgetwc_r(<[ptr]>, <[fp]>)
@@ -68,27 +100,54 @@ TRAD_SYNOPSIS
 
 	#include <stdio.h>
 	#include <wchar.h>
+	wint_t _fgetwc_unlocked_r(<[ptr]>, <[fp]>)
+	struct _reent *<[ptr]>;
+	FILE *<[fp]>;
+
+	#include <stdio.h>
+	#include <wchar.h>
 	wint_t getwc(<[fp]>)
 	FILE *<[fp]>;
 
+	#define _GNU_SOURCE
+	#include <stdio.h>
+	#include <wchar.h>
+	wint_t getwc_unlocked(<[fp]>)
+	FILE *<[fp]>;
+
 	#include <stdio.h>
 	#include <wchar.h>
 	wint_t _getwc_r(<[ptr]>, <[fp]>)
 	struct _reent *<[ptr]>;
 	FILE *<[fp]>;
 
+	#include <stdio.h>
+	#include <wchar.h>
+	wint_t _getwc_unlocked_r(<[ptr]>, <[fp]>)
+	struct _reent *<[ptr]>;
+	FILE *<[fp]>;
+
 DESCRIPTION
 Use <<fgetwc>> to get the next wide character from the file or stream
 identified by <[fp]>.  As a side effect, <<fgetwc>> advances the file's
 current position indicator.
 
-The  <<getwc>>  function  or macro functions identically to <<fgetwc>>.  It
-may be implemented as a macro, and may evaluate its argument more  than
-once. There is no reason ever to use it.
-
-<<_fgetwc_r>> and <<_getwc_r>> are simply reentrant versions of
-<<fgetwc>> and <<getwc>> that are passed the additional reentrant
-structure pointer argument: <[ptr]>.
+<<fgetwc_unlocked>> is a non-thread-safe version of <<fgetwc>>.
+<<fgetwc_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
+<<fgetwc_unlocked>> is equivalent to <<fgetwc>>.
+
+The <<getwc>> and <<getwc_unlocked>> functions or macros functions identically
+to <<fgetwc>> and <<fgetwc_unlocked>>.  It may be implemented as a macro, and
+may evaluate its argument more than once. There is no reason ever to use it.
+
+<<_fgetwc_r>>, <<_getwc_r>>, <<_fgetwc_unlocked_r>>, and <<_getwc_unlocked_r>>
+are simply reentrant versions of the above functions that are passed the
+additional reentrant structure pointer argument: <[ptr]>.
 
 RETURNS
 The next wide character cast to <<wint_t>>), unless there is no more data,
@@ -99,7 +158,9 @@ You can distinguish the two situations t
 using the <<ferror>> and <<feof>> functions.
 
 PORTABILITY
-C99, POSIX.1-2001
+<<fgetwc>> and <<getwc>> are required by C99 and POSIX.1-2001.
+
+<<fgetwc_unlocked>> and <<getwc_unlocked>> are GNU extensions.
 */
 
 #include <_ansi.h>
@@ -110,7 +171,7 @@ C99, POSIX.1-2001
 #include <wchar.h>
 #include "local.h"
 
-static wint_t
+wint_t
 _DEFUN(__fgetwc, (ptr, fp),
 	struct _reent *ptr _AND
 	register FILE *fp)
Index: libc/stdio/fgetwc_u.c
===================================================================
RCS file: libc/stdio/fgetwc_u.c
diff -N libc/stdio/fgetwc_u.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ libc/stdio/fgetwc_u.c	17 Dec 2014 18:26:55 -0000
@@ -0,0 +1,49 @@
+/*
+ * 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 <stdio.h>
+#include <wchar.h>
+#include "local.h"
+
+wint_t
+_DEFUN(_fgetwc_unlocked_r, (ptr, fp),
+	struct _reent *ptr _AND
+	register FILE *fp)
+{
+  ORIENT(fp, 1);
+  return __fgetwc (ptr, fp);
+}
+
+wint_t
+_DEFUN(fgetwc_unlocked, (fp),
+	FILE *fp)
+{
+  struct _reent *reent = _REENT;
+
+  CHECK_INIT(reent, fp);
+  return _fgetwc_unlocked_r (reent, fp);
+}