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Message-ID: <CAECwjAjpzw08ZpP0-97WZu_TyFA05A-dkUmnvDA47GYu1+Tb=w@mail.gmail.com>
Date: Fri, 24 Mar 2017 10:14:02 +0800
From: Yousong Zhou <yszhou4tech@...il.com>
To: musl@...ts.openwall.com
Subject: Re: [PATCH] pthread_sigmask: check 'how' only when 'set' is
not NULL
On 22 March 2017 at 20:49, Rich Felker <dalias@...c.org> wrote:
> On Wed, Mar 22, 2017 at 08:19:43PM +0800, Yousong Zhou wrote:
>> According to POSIX document
>>
>> If set is a null pointer, the value of the argument how is not
>> significant and the thread's signal mask shall be unchanged; thus
>> the call can be used to enquire about currently blocked signals.
>>
>> This is also how the current Linux kernel syscall is doing. So the
>> following function call from binutils-gdb should not fail
>>
>> sigprocmask (0, NULL, &original_signal_mask);
>> ---
>> src/thread/pthread_sigmask.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/src/thread/pthread_sigmask.c b/src/thread/pthread_sigmask.c
>> index 88c333f..f188782 100644
>> --- a/src/thread/pthread_sigmask.c
>> +++ b/src/thread/pthread_sigmask.c
>> @@ -5,7 +5,7 @@
>> int pthread_sigmask(int how, const sigset_t *restrict set, sigset_t *restrict old)
>> {
>> int ret;
>> - if ((unsigned)how - SIG_BLOCK > 2U) return EINVAL;
>> + if (set && (unsigned)how - SIG_BLOCK > 2U) return EINVAL;
>> ret = -__syscall(SYS_rt_sigprocmask, how, set, old, _NSIG/8);
>> if (!ret && old) {
>> if (sizeof old->__bits[0] == 8) {
>> --
>> 2.6.4
>
> I don't think this change is conforming. There is a requirement to
> produce an error ("shall fail") independent of whether the set
> argument is a null pointer:
>
> The pthread_sigmask() and sigprocmask() functions shall fail if:
>
> [EINVAL]
> The value of the how argument is not equal to one of the defined
> values.
>
> http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_sigmask.html
>
> If gdb is calling it with an invalid argument (rather, one that's
> conditionally invalid depending on the platform's definitions of the
> how macros), a patch should be sent to gdb to fix it.
>
> Rich
I think you are right in the interpretation of POSIX document on this
topic. I missed the "shall fail" part in ERRORS section.
But it came to me that darwin was thought to be a certificated
POSIX-compliant environment, so I just ran tested that pthread_sigmask
call on my osx 10.11.6 and it worked without error.
https://en.wikipedia.org/wiki/Darwin_(operating_system)
I will patch gdb anyway, to be correct.
Regards,
yousong
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