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Re: [PATCH 06/20] unlocked stdio extensions
- From: Yaakov Selkowitz <yselkowi at redhat dot com>
- To: newlib at sourceware dot org
- Date: Wed, 17 Dec 2014 14:46:45 -0600
- Subject: Re: [PATCH 06/20] unlocked stdio extensions
- Authentication-results: sourceware.org; auth=none
- References: <548F3554 dot 5010204 at redhat dot com> <20141216112826 dot GJ10824 at calimero dot vinschen dot de> <5491C810 dot 6080305 at redhat dot com> <20141217182008 dot GX10824 at calimero dot vinschen dot de> <5491CCB7 dot 80701 at redhat dot com>
Revised patch attached.
--
Yaakov Selkowitz
Associate Software Engineer, ARM
Red Hat, Inc.
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 20:42:42 -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 +110,11 @@ Supporting OS subroutines required: <<cl
#include <string.h>
#include "local.h"
+#ifdef __IMPL_UNLOCKED__
+#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 20:42:42 -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 "fgets.c"