memory corruption problem

[Wilkes, John]

Thank you for the helpful replies; they guided me to the root cause, which was my linker script. I hadn't accounted for .bss.* sections; they were placed after my _end symbol, so malloc created the stdout buffer on top of some variables.

If I'd looked at the output of "nm" first, I might have noticed that "_end" wasn't at the very end.  ;-)

John

-----Original Message-----
From: Sebastian Huber [mailto:sebastian.huber@embedded-brains.de] 
Sent: Monday, July 11, 2016 10:28 PM
To: Wilkes, John; newlib@sourceware.org
Subject: Re: memory corruption problem



On 11/07/16 18:13, Wilkes, John wrote:
> If _REENT_SMALL is defined, the __sinit(struct _reent *s) function sets s->stdout:
>
> #ifndef _REENT_SMALL
>    s->__sglue._niobs = 3;
>    s->__sglue._iobs = &s->__sf[0];
> #else
>    s->__sglue._niobs = 0;
>    s->__sglue._iobs = NULL;
>    /* Avoid infinite recursion when calling __sfp  for _GLOBAL_REENT.  The
>       problem is that __sfp checks for _GLOBAL_REENT->__sdidinit and calls
>       __sinit if it's 0. */
>    if (s == _GLOBAL_REENT)
>      s->__sdidinit = 1;
>    s->_stdin = __sfp(s);
>    s->_stdout = __sfp(s);
>    s->_stderr = __sfp(s);
> #endif
>
>    std (s->_stdin,  __SRD, 0, s);
>
>
> If _REENT_SMALL is not defined, where is s->_stdout initialized before the call to __sinit()?

For RTEMS we use something like this:

https://git.rtems.org/rtems/tree/cpukit/libcsupport/src/newlibc_reent.c

-- 
Sebastian Huber, embedded brains GmbH

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