From: Sebastian Huber <sebastian.huber@embedded-brains.de>
To: newlib@sourceware.org
Subject: [PATCH 3/3] Introduce _REENT_GLOBAL_STDIO_STREAMS
Date: Fri, 23 Jun 2017 09:23:00 -0000 [thread overview]
Message-ID: <20170623092259.29325-3-sebastian.huber@embedded-brains.de> (raw)
In-Reply-To: <20170623092259.29325-1-sebastian.huber@embedded-brains.de>
In Newlib, the stdio streams are defined to thread-specific pointers
_reent::_stdin, _reent::_stdout and _reent::_stderr. In case
_REENT_SMALL is not defined, then these pointers are initialized via
_REENT_INIT_PTR() or _REENT_INIT_PTR_ZEROED() to thread-specific FILE
objects provided via _reent::__sf[3]. There are two problems with this
(at least in case of RTEMS).
(1) The thread-specific FILE objects are closed by _reclaim_reent().
This leads to problems with language run-time libraries that provide
wrappers to the C/POSIX stdio streams (e.g. C++ and Ada), since they
use the thread-specific FILE objects of the initialization thread. In
case the initialization thread is deleted, then they use freed memory.
(2) Since thread-specific FILE objects are used with a common output
device via file descriptors 0, 1 and 2, the locking at FILE object level
cannot ensure atomicity of the output, e.g. a call to printf().
Introduce a new Newlib configuration option _REENT_GLOBAL_STDIO_STREAMS
to enable the use of global stdio FILE objects. Use this option for RTEMS.
As a side-effect this reduces the size of struct _reent by more than
50%.
The _REENT_GLOBAL_STDIO_STREAMS should not be used without
_STDIO_CLOSE_PER_REENT_STD_STREAMS.
Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>
---
newlib/libc/include/sys/config.h | 1 +
newlib/libc/include/sys/reent.h | 21 +++++++++++++++------
newlib/libc/stdio/findfp.c | 24 ++++++++++++++++++++++++
newlib/libc/stdio/local.h | 2 +-
4 files changed, 41 insertions(+), 7 deletions(-)
diff --git a/newlib/libc/include/sys/config.h b/newlib/libc/include/sys/config.h
index 555239f8b..ae8caff7b 100644
--- a/newlib/libc/include/sys/config.h
+++ b/newlib/libc/include/sys/config.h
@@ -238,6 +238,7 @@
#define _READ_WRITE_RETURN_TYPE _ssize_t
#define __DYNAMIC_REENT__
#define _REENT_GLOBAL_ATEXIT
+#define _REENT_GLOBAL_STDIO_STREAMS
#endif
#ifndef __EXPORT
diff --git a/newlib/libc/include/sys/reent.h b/newlib/libc/include/sys/reent.h
index 8b67889ac..2a79ccc71 100644
--- a/newlib/libc/include/sys/reent.h
+++ b/newlib/libc/include/sys/reent.h
@@ -644,14 +644,23 @@ struct _reent
of the above members (on the off chance that future binary compatibility
would be broken otherwise). */
struct _glue __sglue; /* root of glue chain */
+# ifndef _REENT_GLOBAL_STDIO_STREAMS
__FILE __sf[3]; /* first three file descriptors */
+# endif
};
+#ifdef _REENT_GLOBAL_STDIO_STREAMS
+extern __FILE __sf[3];
+#define _REENT_STDIO_STREAM(var, index) &__sf[index]
+#else
+#define _REENT_STDIO_STREAM(var, index) &(var).__sf[index]
+#endif
+
#define _REENT_INIT(var) \
{ 0, \
- &(var).__sf[0], \
- &(var).__sf[1], \
- &(var).__sf[2], \
+ _REENT_STDIO_STREAM(var, 0), \
+ _REENT_STDIO_STREAM(var, 1), \
+ _REENT_STDIO_STREAM(var, 2), \
0, \
"", \
0, \
@@ -696,9 +705,9 @@ struct _reent
}
#define _REENT_INIT_PTR_ZEROED(var) \
- { (var)->_stdin = &(var)->__sf[0]; \
- (var)->_stdout = &(var)->__sf[1]; \
- (var)->_stderr = &(var)->__sf[2]; \
+ { (var)->_stdin = _REENT_STDIO_STREAM(var, 0); \
+ (var)->_stdout = _REENT_STDIO_STREAM(var, 1); \
+ (var)->_stderr = _REENT_STDIO_STREAM(var, 2); \
(var)->_new._reent._rand_next = 1; \
(var)->_new._reent._r48._seed[0] = _RAND48_SEED_0; \
(var)->_new._reent._r48._seed[1] = _RAND48_SEED_1; \
diff --git a/newlib/libc/stdio/findfp.c b/newlib/libc/stdio/findfp.c
index 601795098..ffeb019fa 100644
--- a/newlib/libc/stdio/findfp.c
+++ b/newlib/libc/stdio/findfp.c
@@ -35,6 +35,10 @@ const struct __sFILE_fake __sf_fake_stderr =
{_NULL, 0, 0, 0, 0, {_NULL, 0}, 0, _NULL};
#endif
+#ifdef _REENT_GLOBAL_STDIO_STREAMS
+__FILE __sf[3];
+#endif
+
#if (defined (__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED))
_NOINLINE_STATIC _VOID
#else
@@ -218,6 +222,14 @@ _DEFUN(_cleanup_r, (ptr),
cleanup_func = _fclose_r;
#endif
#endif
+#ifdef _REENT_GLOBAL_STDIO_STREAMS
+ if (ptr->_stdin != &__sf[0])
+ (*cleanup_func) (ptr, ptr->_stdin);
+ if (ptr->_stdout != &__sf[1])
+ (*cleanup_func) (ptr, ptr->_stdout);
+ if (ptr->_stderr != &__sf[2])
+ (*cleanup_func) (ptr, ptr->_stderr);
+#endif
_CAST_VOID _fwalk_reent (ptr, cleanup_func);
}
@@ -250,8 +262,10 @@ _DEFUN(__sinit, (s),
s->__sglue._next = NULL;
#ifndef _REENT_SMALL
+# ifndef _REENT_GLOBAL_STDIO_STREAMS
s->__sglue._niobs = 3;
s->__sglue._iobs = &s->__sf[0];
+# endif
#else
s->__sglue._niobs = 0;
s->__sglue._iobs = NULL;
@@ -265,9 +279,19 @@ _DEFUN(__sinit, (s),
s->_stderr = __sfp(s);
#endif
+#ifdef _REENT_GLOBAL_STDIO_STREAMS
+ if (__sf[0]._cookie == NULL) {
+ _GLOBAL_REENT->__sglue._niobs = 3;
+ _GLOBAL_REENT->__sglue._iobs = &__sf[0];
+ stdin_init (&__sf[0]);
+ stdout_init (&__sf[1]);
+ stderr_init (&__sf[2]);
+ }
+#else
stdin_init (s->_stdin);
stdout_init (s->_stdout);
stderr_init (s->_stderr);
+#endif
s->__sdidinit = 1;
diff --git a/newlib/libc/stdio/local.h b/newlib/libc/stdio/local.h
index 5f6995501..511e5e35f 100644
--- a/newlib/libc/stdio/local.h
+++ b/newlib/libc/stdio/local.h
@@ -38,7 +38,7 @@
case _STDIO_CLOSE_PER_REENT_STD_STREAMS is defined these file descriptors
will be closed via close() provided the owner of the reent structure
triggerd the on demand reent initilization, see CHECK_INIT(). */
-#if !defined(__rtems__) && !defined(__tirtos__)
+#if !defined(__tirtos__)
#define _STDIO_CLOSE_PER_REENT_STD_STREAMS
#endif
--
2.12.3
next prev parent reply other threads:[~2017-06-23 9:23 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-23 9:23 [PATCH 1/3] Remove superfluous parameter from std() Sebastian Huber
2017-06-23 9:23 ` [PATCH 2/3] Add stdin_init(), stdout_init() and stderr_init() Sebastian Huber
2017-06-23 14:02 ` Corinna Vinschen
2017-06-26 6:15 ` Sebastian Huber
2017-06-26 6:24 ` Sebastian Huber
2017-06-26 8:22 ` Corinna Vinschen
2017-06-23 9:23 ` Sebastian Huber [this message]
2017-06-23 21:53 ` [PATCH 3/3] Introduce _REENT_GLOBAL_STDIO_STREAMS Freddie Chopin
2017-06-26 5:59 ` Sebastian Huber
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