Re: [PATCH 12/20] unlocked stdio extensions

[Yaakov Selkowitz <yselkowi at redhat dot com>]

Index: libc/stdio/fputwc.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/fputwc.c,v
retrieving revision 1.4
diff -u -p -r1.4 fputwc.c
--- libc/stdio/fputwc.c	29 Apr 2013 21:06:23 -0000	1.4
+++ libc/stdio/fputwc.c	17 Dec 2014 18:27:08 -0000
@@ -26,34 +26,60 @@
 
 /*
 FUNCTION
-<<fputwc>>, <<putwc>>---write a wide character on a stream or file
+<<fputwc>>, <<putwc>>, <<fputwc_unlocked>>, <<putwc_unlocked>>---write a wide character on a stream or file
 
 INDEX
 	fputwc
 INDEX
+	fputwc_unlocked
+INDEX
 	_fputwc_r
 INDEX
+	_fputwc_unlocked_r
+INDEX
 	putwc
 INDEX
+	putwc_unlocked
+INDEX
 	_putwc_r
+INDEX
+	_putwc_unlocked_r
 
 ANSI_SYNOPSIS
 	#include <stdio.h>
 	#include <wchar.h>
 	wint_t fputwc(wchar_t <[wc]>, FILE *<[fp]>);
 
+	#define _GNU_SOURCE
+	#include <stdio.h>
+	#include <wchar.h>
+	wint_t fputwc_unlocked(wchar_t <[wc]>, FILE *<[fp]>);
+
 	#include <stdio.h>
 	#include <wchar.h>
 	wint_t _fputwc_r(struct _reent *<[ptr]>, wchar_t <[wc]>, FILE *<[fp]>);
 
 	#include <stdio.h>
 	#include <wchar.h>
+	wint_t _fputwc_unlocked_r(struct _reent *<[ptr]>, wchar_t <[wc]>, FILE *<[fp]>);
+
+	#include <stdio.h>
+	#include <wchar.h>
 	wint_t putwc(wchar_t <[wc]>, FILE *<[fp]>);
 
+	#define _GNU_SOURCE
+	#include <stdio.h>
+	#include <wchar.h>
+	wint_t putwc_unlocked(wchar_t <[wc]>, FILE *<[fp]>);
+
 	#include <stdio.h>
 	#include <wchar.h>
 	wint_t _putwc_r(struct _reent *<[ptr]>, wchar_t <[wc]>, FILE *<[fp]>);
 
+	#include <stdio.h>
+	#include <wchar.h>
+	wint_t _putwc_unlocked_r(struct _reent *<[ptr]>, wchar_t <[wc]>, FILE *<[fp]>);
+
 TRAD_SYNOPSIS
 	#include <stdio.h>
 	#include <wchar.h>
@@ -61,6 +87,13 @@ TRAD_SYNOPSIS
 	wchar_t <[wc]>;
 	FILE *<[fp]>;
 
+	#define _GNU_SOURCE
+	#include <stdio.h>
+	#include <wchar.h>
+	wint_t fputwc_unlocked(<[wc]>, <[fp]>)
+	wchar_t <[wc]>;
+	FILE *<[fp]>;
+
 	#include <stdio.h>
 	#include <wchar.h>
 	wint_t _fputwc_r(<[ptr]>, <[wc]>, <[fp]>)
@@ -70,10 +103,24 @@ TRAD_SYNOPSIS
 
 	#include <stdio.h>
 	#include <wchar.h>
+	wint_t _fputwc_unlocked_r(<[ptr]>, <[wc]>, <[fp]>)
+	struct _reent *<[ptr]>;
+	wchar_t <[wc]>;
+	FILE *<[fp]>;
+
+	#include <stdio.h>
+	#include <wchar.h>
 	wint_t putwc(<[wc]>, <[fp]>)
 	wchar_t <[wc]>;
 	FILE *<[fp]>;
 
+	#define _GNU_SOURCE
+	#include <stdio.h>
+	#include <wchar.h>
+	wint_t putwc_unlocked(<[wc]>, <[fp]>)
+	wchar_t <[wc]>;
+	FILE *<[fp]>;
+
 	#include <stdio.h>
 	#include <wchar.h>
 	wint_t _putwc_r(<[ptr]>, <[wc]>, <[fp]>)
@@ -81,6 +128,13 @@ TRAD_SYNOPSIS
 	wchar_t <[wc]>;
 	FILE *<[fp]>;
 
+	#include <stdio.h>
+	#include <wchar.h>
+	wint_t _putwc_unlocked_r(<[ptr]>, <[wc]>, <[fp]>)
+	struct _reent *<[ptr]>;
+	wchar_t <[wc]>;
+	FILE *<[fp]>;
+
 DESCRIPTION
 <<fputwc>> writes the wide character argument <[wc]> to the file or
 stream identified by <[fp]>.
@@ -91,13 +145,22 @@ file or stream.  Otherwise, the new wide
 current value of the position indicator, and the position indicator
 oadvances by one.
 
-The <<putwc>> function or macro functions identically to <<fputwc>>.  It
-may be implemented as a macro, and may evaluate its argument more than
-once. There is no reason ever to use it.
-
-The <<_fputwc_r>> and <<_putwc_r>> functions are simply reentrant versions
-of <<fputwc>> and <<putwc>> that take an additional reentrant structure
-argument: <[ptr]>.
+<<fputwc_unlocked>> is a non-thread-safe version of <<fputwc>>.
+<<fputwc_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
+<<fputwc_unlocked>> is equivalent to <<fputwc>>.
+
+The <<putwc>> and <<putwc_unlocked>> functions or macros function identically
+to <<fputwc>> and <<fputwc_unlocked>>.  They may be implemented as a macro, and
+may evaluate its argument more than once. There is no reason ever to use them.
+
+The <<_fputwc_r>>, <<_putwc_r>>, <<_fputwc_unlocked_r>>, and
+<<_putwc_unlocked_r>> functions are simply reentrant versions of the above
+that take an additional reentrant structure argument: <[ptr]>.
 
 RETURNS
 If successful, <<fputwc>> and <<putwc>> return their argument <[wc]>.
@@ -105,7 +168,9 @@ If an error intervenes, the result is <<
 `<<ferror(<[fp]>)>>' to query for errors.
 
 PORTABILITY
-C99, POSIX.1-2001
+<<fputwc>> and <<putwc>> are required by C99 and POSIX.1-2001.
+
+<<fputwc_unlocked>> and <<putwc_unlocked>> are GNU extensions.
 */
 
 #include <_ansi.h>
@@ -117,7 +182,7 @@ C99, POSIX.1-2001
 #include <wchar.h>
 #include "local.h"
 
-static wint_t
+wint_t
 _DEFUN(__fputwc, (ptr, wc, fp),
 	struct _reent *ptr _AND
 	wchar_t wc _AND
Index: libc/stdio/fputwc_u.c
===================================================================
RCS file: libc/stdio/fputwc_u.c
diff -N libc/stdio/fputwc_u.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ libc/stdio/fputwc_u.c	17 Dec 2014 18:27:08 -0000
@@ -0,0 +1,51 @@
+/*
+ * 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(_fputwc_unlocked_r, (ptr, wc, fp),
+	struct _reent *ptr _AND
+	wchar_t wc _AND
+	FILE *fp)
+{
+  ORIENT(fp, 1);
+  return __fputwc(ptr, wc, fp);
+}
+
+wint_t
+_DEFUN(fputwc_unlocked, (wc, fp),
+	wchar_t wc _AND
+	FILE *fp)
+{
+  struct _reent *reent = _REENT;
+
+  CHECK_INIT(reent, fp);
+  return _fputwc_unlocked_r (reent, wc, fp);
+}