Re: [Qemu-devel] [PATCH] exec.c: Initialize sa_flags passed to sigaction()

[Eric Blake <eblake@redhat.com>]

On 05/15/2018 03:53 PM, Philippe Mathieu-Daudé wrote:
> On 05/15/2018 03:27 PM, Peter Maydell wrote:
>> Coverity points out that in the user-only version of cpu_abort() we
>> call sigaction() with a partially initialized struct sigaction
>> (CID 1005351). Correct the omission.
>>
>> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
>> ---
>>   exec.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/exec.c b/exec.c
>> index ffa1099547..bd8833fc9d 100644
>> --- a/exec.c
>> +++ b/exec.c
>> @@ -1124,6 +1124,7 @@ void cpu_abort(CPUState *cpu, const char *fmt, ...)
>>           struct sigaction act;
> 
> I'd have used the more generic:
> 
>             struct sigaction act = { };

That's a gcc/clang extension (although we have used it before, 
particularly to shut up buggy versions of clang); better is:

struct sigaction act = { 0 };

if that doesn't trigger the clang bug.

> 
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> 
>>           sigfillset(&act.sa_mask);
>>           act.sa_handler = SIG_DFL;

The sigfillset() has to be done after initialization, but you could also 
use:

struct sigaction act = {
   .sa_handler = SIG_DFL;
};
sigfillset(&act.sa_mask);

as a way to zero-initialize all other fields.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org