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Re: How to destroy _reent structure

On 24/04/13 13:10, Sebastian Huber wrote:
Hello Corinna,

On 04/24/2013 12:26 PM, Corinna Vinschen wrote:
On Apr 24 10:04, Sebastian Huber wrote:

there is _REENT_INIT_PTR() for initialization, but how can I destroy
a _reent structure.  Is this _wrapup_reent()?

Try _reclaim_reent.  But it's not the same as _REENT_INIT_PTR since
_REENT_INIT_PTR does not allocate any memory.


so for initialization we can use:

struct _reent *p = malloc(sizeof(*p));
if (p != NULL) {

For destruction we can use:


If I use this sequence in RTEMS, then I have the following problem. RTEMS opens (via open()) the file descriptors 0, 1 and 2 during system initialization. In RTEMS the file descriptors are a global resource. A thread will do the initialization steps above during creation time. Now suppose a thread calls fopen(). This will check that _REENT is initialized. This will execute the following code for stdin, stdout and stderr FILE streams (newlib/libc/stdio/findfp.c):

static _VOID
_DEFUN(std, (ptr, flags, file, data),
            FILE *ptr _AND
            int flags _AND
            int file  _AND
            struct _reent *data)
  ptr->_file = file;
  ptr->_close = __sclose;

It simply assumes that file descriptors 0, 1 and 2 are available and registers the __sclose() function (which will call close()). During _reclaim_reent() the stdin, stdout and stderr FILE streams are closed. Since we have no open() call for these file descriptors this will close the global file descriptors 0, 1 and 2. I think at least for RTEMS we should set ptr->_close to NULL.

What is the purpose of _wrapup_reent()? Its not called from within Newlib and I don't find a function that can register an atexit handler in a non-global _reent structure. There is also no public header file for this function.

I think we should move the _wrapup_reent() into a separate file.

Sebastian Huber, embedded brains GmbH

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