Re: [PATCH v3 3/5] Introduce _REENT_GLOBAL_STDIO_STREAMS

[Corinna Vinschen <vinschen at redhat dot com>]

On Jun 29 14:20, Sebastian Huber wrote:
> 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.

Patch series looks good, builds and works on Cygwin, so I think this
is good to go.  Please push.

And, JFYI, Cygwin will start to use it too after the next release :)


Thanks,
Corinna

-- 
Corinna Vinschen
Cygwin Maintainer
Red Hat

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