Re: [PATCH 03/20] unlocked stdio extensions

[Yaakov Selkowitz <yselkowi at redhat dot com>]

Index: libc/stdio/ferror.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/ferror.c,v
retrieving revision 1.6
diff -u -p -r1.6 ferror.c
--- libc/stdio/ferror.c	30 May 2012 08:58:42 -0000	1.6
+++ libc/stdio/ferror.c	17 Dec 2014 18:26:45 -0000
@@ -17,20 +17,31 @@
 
 /*
 FUNCTION
-<<ferror>>---test whether read/write error has occurred
+<<ferror>>, <<ferror_unlocked>>---test whether read/write error has occurred
 
 INDEX
 	ferror
+INDEX
+	ferror_unlocked
 
 ANSI_SYNOPSIS
 	#include <stdio.h>
 	int ferror(FILE *<[fp]>);
 
+	#define _BSD_SOURCE
+	#include <stdio.h>
+	int ferror_unlocked(FILE *<[fp]>);
+
 TRAD_SYNOPSIS
 	#include <stdio.h>
 	int ferror(<[fp]>)
 	FILE *<[fp]>;
 
+	#define _BSD_SOURCE
+	#include <stdio.h>
+	int ferror_unlocked(<[fp]>)
+	FILE *<[fp]>;
+
 DESCRIPTION
 The <<stdio>> functions maintain an error indicator with each file
 pointer <[fp]>, to record whether any read or write errors have
@@ -39,6 +50,15 @@ Use <<ferror>> to query this indicator.
 
 See <<clearerr>> to reset the error indicator.
 
+<<ferror_unlocked>> is a non-thread-safe version of <<ferror>>.
+<<ferror_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
+<<ferror_unlocked>> is equivalent to <<ferror>>.
+
 RETURNS
 <<ferror>> returns <<0>> if no errors have occurred; it returns a
 nonzero value otherwise.
@@ -46,6 +66,8 @@ nonzero value otherwise.
 PORTABILITY
 ANSI C requires <<ferror>>.
 
+<<ferror_unlocked>> is a BSD extension also provided by GNU libc.
+
 No supporting OS subroutines are required.
 */
 
Index: libc/stdio/ferror_u.c
===================================================================
RCS file: libc/stdio/ferror_u.c
diff -N libc/stdio/ferror_u.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ libc/stdio/ferror_u.c	17 Dec 2014 18:26:45 -0000
@@ -0,0 +1,41 @@
+/*
+ * 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 "local.h"
+
+/* A subroutine version of the macro ferror_unlocked.  */
+
+#undef ferror_unlocked
+
+int
+_DEFUN(ferror_unlocked, (fp),
+       FILE * fp)
+{
+  CHECK_INIT(_REENT, fp);
+  return __sferror (fp);
+}