Re: [PATCH] Fix stdio init handling

[Sebastian Huber <sebastian.huber@embedded-brains.de>]

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Hello Hans-Peter,

sorry for breaking your Newlib configuration. I was able to reproduce 
the issue in RTEMS with a corresponding configuration. The problem 
didn't show up in our tests since in RTEMS __getreent() returns a 
thread-specific reentrancy structure. With

struct _reent *
__getreent (void)
{
   return _impure_ptr;
}

your test case reproduced the issue. Could you please try the attached 
patch?

We would like to introduce a configuration option for Newlib to use 
thread-local storage for the members of struct _reent:

https://sourceware.org/pipermail/newlib/2022/018855.html

With this option, struct _reent is not defined, so using members of 
_GLOBAL_REENT to maintain global Newlib state would not work. This is 
why we tried to use dedicated global objects for the FILE object list 
and the exit handlers.

We also would like to make the _REENT_GLOBAL_STDIO_STREAMS option the 
default Newlib behaviour:

https://sourceware.org/pipermail/newlib/2022/019735.html

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From 9629ec0b7a2e657d693960269506fcc6c715c6ff Mon Sep 17 00:00:00 2001
From: Sebastian Huber <sebastian.huber@embedded-brains.de>
Date: Tue, 7 Jun 2022 07:55:02 +0200
Subject: [PATCH] Fix __sglue inititialization

Do not initialize __sglue with the FILE objects of _GLOBAL_REENT to avoid a
double use in the !_REENT_SMALL and !_REENT_GLOBAL_STDIO_STREAMS configurations
which didn't use a thread-specific reentrancy structure.
---
 newlib/libc/stdio/findfp.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/newlib/libc/stdio/findfp.c b/newlib/libc/stdio/findfp.c
index 6933ff1db..ff6804d19 100644
--- a/newlib/libc/stdio/findfp.c
+++ b/newlib/libc/stdio/findfp.c
@@ -41,11 +41,7 @@ const struct __sFILE_fake __sf_fake_stderr =
 __FILE __sf[3];
 struct _glue __sglue = {NULL, 3, &__sf[0]};
 #else
-#ifdef _REENT_SMALL
 struct _glue __sglue = {NULL, 0, NULL};
-#else
-struct _glue __sglue = {NULL, 3, &_GLOBAL_REENT->__sf[0]};
-#endif
 #endif
 
 #ifdef _STDIO_BSD_SEMANTICS
-- 
2.35.3