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>
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