Re: [PATCH 3/5] Introduce _REENT_GLOBAL_STDIO_STREAMS

[Corinna Vinschen <vinschen at redhat dot com>]

Hi Sebastian,

On Jun 29 08:18, 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%.

This doesn't build for me with all patches applied:

winsup/cygwin/cygtls.cc:55:7: error: request for member ‘__sf’ in ‘&((_cygtls*)this)->_cygtls::<anonymous>._cygtls::<anonymous union>::local_clib’, which is of pointer type ‘_reent*’ (maybe you meant to use ‘->’ ?)
       _REENT_INIT_PTR (&local_clib);


Corinna

-- 
Corinna Vinschen
Cygwin Maintainer
Red Hat

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