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Message-ID: <20170322124921.GE17319@brightrain.aerifal.cx>
Date: Wed, 22 Mar 2017 08:49:21 -0400
From: Rich Felker <dalias@...c.org>
To: musl@...ts.openwall.com
Subject: Re: [PATCH] pthread_sigmask: check 'how' only when 'set' is
not NULL
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
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