Re: [PATCH 15/20] unlocked stdio extensions

[Yaakov Selkowitz <yselkowi at redhat dot com>]

Revised patch attached.

--
Yaakov Selkowitz
Associate Software Engineer, ARM
Red Hat, Inc.

Index: libc/stdio/fwrite.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/fwrite.c,v
retrieving revision 1.11
diff -u -p -r1.11 fwrite.c
--- libc/stdio/fwrite.c	18 Nov 2013 17:28:05 -0000	1.11
+++ libc/stdio/fwrite.c	17 Dec 2014 20:42:56 -0000
@@ -17,22 +17,35 @@
 
 /*
 FUNCTION
-<<fwrite>>---write array elements
+<<fwrite>>, <<fwrite_unlocked>>---write array elements
 
 INDEX
 	fwrite
 INDEX
+	fwrite_unlocked
+INDEX
 	_fwrite_r
+INDEX
+	_fwrite_unlocked_r
 
 ANSI_SYNOPSIS
 	#include <stdio.h>
 	size_t fwrite(const void *restrict <[buf]>, size_t <[size]>,
 		      size_t <[count]>, FILE *restrict <[fp]>);
 
+	#define _BSD_SOURCE
+	#include <stdio.h>
+	size_t fwrite_unlocked(const void *restrict <[buf]>, size_t <[size]>,
+		      size_t <[count]>, FILE *restrict <[fp]>);
+
 	#include <stdio.h>
 	size_t _fwrite_r(struct _reent *<[ptr]>, const void *restrict <[buf]>, size_t <[size]>,
 		      size_t <[count]>, FILE *restrict <[fp]>);
 
+	#include <stdio.h>
+	size_t _fwrite_unlocked_r(struct _reent *<[ptr]>, const void *restrict <[buf]>, size_t <[size]>,
+		      size_t <[count]>, FILE *restrict <[fp]>);
+
 TRAD_SYNOPSIS
 	#include <stdio.h>
 	size_t fwrite(<[buf]>, <[size]>, <[count]>, <[fp]>)
@@ -41,6 +54,14 @@ TRAD_SYNOPSIS
 	size_t <[count]>;
 	FILE *<[fp]>;
 
+	#define _BSD_SOURCE
+	#include <stdio.h>
+	size_t fwrite_unlocked(<[buf]>, <[size]>, <[count]>, <[fp]>)
+	char *<[buf]>;
+	size_t <[size]>;
+	size_t <[count]>;
+	FILE *<[fp]>;
+
 	#include <stdio.h>
 	size_t _fwrite_r(<[ptr]>, <[buf]>, <[size]>, <[count]>, <[fp]>)
 	struct _reent *<[ptr]>;
@@ -49,6 +70,14 @@ TRAD_SYNOPSIS
 	size_t <[count]>;
 	FILE *<[fp]>;
 
+	#include <stdio.h>
+	size_t _fwrite_unlocked_r(<[ptr]>, <[buf]>, <[size]>, <[count]>, <[fp]>)
+	struct _reent *<[ptr]>;
+	char *<[buf]>;
+	size_t <[size]>;
+	size_t <[count]>;
+	FILE *<[fp]>;
+
 DESCRIPTION
 <<fwrite>> attempts to copy, starting from the memory location
 <[buf]>, <[count]> elements (each of size <[size]>) into the file or
@@ -58,8 +87,17 @@ stream identified by <[fp]>.  <<fwrite>>
 <<fwrite>> also advances the file position indicator (if any) for
 <[fp]> by the number of @emph{characters} actually written.
 
-<<_fwrite_r>> is simply the reentrant version of <<fwrite>> that
-takes an additional reentrant structure argument: <[ptr]>.
+<<fwrite_unlocked>> is a non-thread-safe version of <<fwrite>>.
+<<fwrite_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
+<<fwrite_unlocked>> is equivalent to <<fwrite>>.
+
+<<_fwrite_r>> and <<_fwrite_unlocked_r>> are simply reentrant versions of the
+above that take an additional reentrant structure argument: <[ptr]>.
 
 RETURNS
 If <<fwrite>> succeeds in writing all the elements you specify, the
@@ -70,6 +108,8 @@ the file.
 PORTABILITY
 ANSI C requires <<fwrite>>.
 
+<<fwrite_unlocked>> is a BSD extension also provided by GNU libc.
+
 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
 <<lseek>>, <<read>>, <<sbrk>>, <<write>>.
 */
@@ -89,6 +129,11 @@ static char sccsid[] = "%W% (Berkeley) %
 #include "fvwrite.h"
 #endif
 
+#ifdef __IMPL_UNLOCKED__
+#define _fwrite_r _fwrite_unlocked_r
+#define fwrite fwrite_unlocked
+#endif
+
 /*
  * Write `count' objects (each size `size') from memory to the given file.
  * Return the number of whole objects written.
Index: libc/stdio/fwrite_u.c
===================================================================
RCS file: libc/stdio/fwrite_u.c
diff -N libc/stdio/fwrite_u.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ libc/stdio/fwrite_u.c	17 Dec 2014 20:42:56 -0000
@@ -0,0 +1,28 @@
+/*
+ * 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.
+ */
+
+#define __IMPL_UNLOCKED__
+#include "fwrite.c"