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Introduce _REENT_GLOBAL_STDIO_STREAMS 

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.

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>
This commit is contained in:
Sebastian Huber 2017-06-22 09:22:47 +02:00
parent 79cc9cb8f3
commit 668a4c8722
2 changed files with 39 additions and 6 deletions
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21
newlib/libc/include/sys/reent.h
View File

@ -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; \

24
newlib/libc/stdio/findfp.c
View File

@ -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
@ -217,6 +221,14 @@ _DEFUN(_cleanup_r, (ptr),
#else
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;