Re: [PATCH 06/20] unlocked stdio extensions

[Yaakov Selkowitz <yselkowi at redhat dot com>]

Index: libc/stdio/fgets.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/fgets.c,v
retrieving revision 1.12
diff -u -p -r1.12 fgets.c
--- libc/stdio/fgets.c	18 Nov 2013 17:28:05 -0000	1.12
+++ libc/stdio/fgets.c	17 Dec 2014 18:26:53 -0000
@@ -17,20 +17,31 @@
 
 /*
 FUNCTION
-<<fgets>>---get character string from a file or stream
+<<fgets>>, <<fgets_unlocked>>---get character string from a file or stream
 
 INDEX
 	fgets
 INDEX
+	fgets_unlocked
+INDEX
 	_fgets_r
+INDEX
+	_fgets_unlocked_r
 
 ANSI_SYNOPSIS
         #include <stdio.h>
 	char *fgets(char *restrict <[buf]>, int <[n]>, FILE *restrict <[fp]>);
 
+	#define _GNU_SOURCE
+        #include <stdio.h>
+	char *fgets_unlocked(char *restrict <[buf]>, int <[n]>, FILE *restrict <[fp]>);
+
         #include <stdio.h>
 	char *_fgets_r(struct _reent *<[ptr]>, char *restrict <[buf]>, int <[n]>, FILE *restrict <[fp]>);
 
+        #include <stdio.h>
+	char *_fgets_unlocked_r(struct _reent *<[ptr]>, char *restrict <[buf]>, int <[n]>, FILE *restrict <[fp]>);
+
 TRAD_SYNOPSIS
 	#include <stdio.h>
 	char *fgets(<[buf]>,<[n]>,<[fp]>)
@@ -38,6 +49,13 @@ TRAD_SYNOPSIS
 	int <[n]>;
 	FILE *<[fp]>;
 
+	#define _GNU_SOURCE
+	#include <stdio.h>
+	char *fgets_unlocked(<[buf]>,<[n]>,<[fp]>)
+        char *<[buf]>;
+	int <[n]>;
+	FILE *<[fp]>;
+
 	#include <stdio.h>
 	char *_fgets_r(<[ptr]>, <[buf]>,<[n]>,<[fp]>)
 	struct _reent *<[ptr]>;
@@ -45,14 +63,30 @@ TRAD_SYNOPSIS
 	int <[n]>;
 	FILE *<[fp]>;
 
+	#include <stdio.h>
+	char *_fgets_unlocked_r(<[ptr]>, <[buf]>,<[n]>,<[fp]>)
+	struct _reent *<[ptr]>;
+        char *<[buf]>;
+	int <[n]>;
+	FILE *<[fp]>;
+
 DESCRIPTION
 	Reads at most <[n-1]> characters from <[fp]> until a newline
 	is found. The characters including to the newline are stored
 	in <[buf]>. The buffer is terminated with a 0.
 
-	The <<_fgets_r>> function is simply the reentrant version of
-	<<fgets>> and is passed an additional reentrancy structure
-	pointer: <[ptr]>.
+	<<fgets_unlocked>> is a non-thread-safe version of <<fgets>>.
+	<<fgets_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
+	<<fgets_unlocked>> is equivalent to <<fgets>>.
+
+	The functions <<_fgets_r>> and <<_fgets_unlocked_r>> are simply
+	reentrant versions that are passed the additional reentrant structure
+	pointer argument: <[ptr]>.
 
 RETURNS
 	<<fgets>> returns the buffer passed to it, with the data
@@ -65,6 +99,8 @@ PORTABILITY
 	that <<fgets>> returns all of the data, while <<gets>> removes
 	the trailing newline (with no indication that it has done so.)
 
+	<<fgets_unlocked>> is a GNU extension.
+
 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
 <<lseek>>, <<read>>, <<sbrk>>, <<write>>.
 */
@@ -74,6 +110,17 @@ Supporting OS subroutines required: <<cl
 #include <string.h>
 #include "local.h"
 
+#ifdef FGETS_UNLOCKED
+#undef _newlib_flockfile_start
+#undef _newlib_flockfile_exit
+#undef _newlib_flockfile_end
+#define _newlib_flockfile_start(x) {}
+#define _newlib_flockfile_exit(x) {}
+#define _newlib_flockfile_end(x) {}
+#define _fgets_r _fgets_unlocked_r
+#define fgets fgets_unlocked
+#endif
+
 /*
  * Read at most n-1 characters from the given file.
  * Stop when a newline has been read, or the count runs out.
Index: libc/stdio/fgets_u.c
===================================================================
RCS file: libc/stdio/fgets_u.c
diff -N libc/stdio/fgets_u.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ libc/stdio/fgets_u.c	17 Dec 2014 18:26:53 -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 FGETS_UNLOCKED
+#include "fgets.c"