Peter Soetens wrote:
> On Monday 10 January 2011 17:24:28 Gilles Chanteperdrix wrote:
>> Peter Soetens wrote:
>>> Hi,
>>>
>>> A while ago, I was advised to call xeno_sigshadow_install() after a
>>> library installed a sigwinch signal handler (I believe this was Xenomai
>>> 2.5.1). Could it be that this is no longer supported in recent versions
>>> ? What is the correct way to avoid a segfault if an application
>>> installed a sigwinch handler after Xenomai did ?
>> I think we already answered that at the time, but if you install your
>> own sigwinch handler, you should:
>> - register it with the SA_SIGINFO flag
>> - call xeno_sigwinch_handler and consider that the signal is for the
>> application only if this function returns 0.
>
> This is indeed in the API docs, but it's not an option since it's a third
> party library (readline) doing this, it doesn't depend on or know Xenomai.
>
>> If you can not do that, then redefine SIGSHADOW in
>> include/asm-generic/syscall.h to a different value, and recompile both
>> Xenomai user-space and kernel-space support. Note however that when
>> starting applications in gdb you will then have to type:
>>
>> handle <the_new_signal> pass nostop print
>>
>> If you want to be able to debug Xenomai applications.
>
> Hmm....
>
> So defining the xeno_sigshadow_install() function ourselves (since it's not
> in
> any Xenomai header) and calling it after the readline signal handlers were
> installed is not gonna work ?
The thing is that xeno_sigshadow_installi is an internal function,
particularily, it is not thread safe. The exported function is
xeno_sigshadow_install_once, but it will not do anything the second time
it gets called.
If you take care of this thread-safety issue, calling
xeno_sigshadow_install should be OK, since it just installs
xeno_sigshadow_handler as a handler for SIGSHADOW, calling
xeno_sigwinch_handler, then the handler your application registered
before. All this code is relatively simple, and you will find it in
src/skins/common/sigshadow.c
Now, I suspect the issue you have is something else, so, could you post
the faulting code, reduced to a simple self-contained test case?
--
Gilles.
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