X-Recipient: archive-cygwin AT delorie DOT com
DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:to:from:subject:message-id:date:mime-version
	:content-type:content-transfer-encoding; q=dns; s=default; b=pRL
	0TQ0eEJM1LcCbE1sty8f0YCtYv3BQaw1QQrHbs8YH68rGHz6r8NzSc1/sLJ6JId3
	XGpec5IQWNeiRy5WeFNwXQQiBstkUq1/Xz10OA0EMcyTBHPCn+jjkhn++4W/3e/R
	7Fv9jBj/AK/sVnb07o3PeBJMcP0DCLatQe5mFKx0=
DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:to:from:subject:message-id:date:mime-version
	:content-type:content-transfer-encoding; s=default; bh=NMqpnoh5F
	ZzZwI34Te/PosTmNZA=; b=BVvDHEoIE3fElWZ+tEHPm5ev7DtMIrnyuM1RRFcgi
	SwFNUhQ6mVZuwN8XmcnE1R1CRc+3axg7IkC0G7lMdZXvaMZDy1xDedg4S70mwbwM
	Yu+MYPQpGWBDjjR/YKj2oFFVfnARqnEHW9iqe27X2sCrUxd1cDfKA5L2zz+6IpUR
	kM=
Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id: <cygwin.cygwin.com>
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com
Authentication-Results: sourceware.org; auth=none
X-Spam-SWARE-Status: No, score=-0.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM,FROM_EXCESS_BASE64,RCVD_IN_DNSWL_NONE,SPF_PASS autolearn=no version=3.3.1 spammy=HX-Google-Smtp-Source:APXvYqz, act
X-HELO: mail-wr1-f49.google.com
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;        d=gmail.com; s=20161025;        h=to:from:subject:message-id:disposition-notification-to:date         :user-agent:mime-version:content-language:content-transfer-encoding;        bh=mdmfTucob7U58RIJQK0XK9gCzww2l9NTZFkuQDvyRVM=;        b=hcqbcj2tRRldmmi7PCJuJCMN1P5awePhzCaVPlgzRw5jLZY379pC8M0dETdVruBTcq         iiweM2ki2q0NW0wOC+R8li2TmWomoum52RopKUrD0iPVh7Oay+dwdns7DNkp2LevPI0y         k4jit/+8+axKtViICu+BXFXttwn8rX2IXhtdZjAcEB9aB+H9GKu1T3ditAh0hfieqmBf         QZwjjjr+f+Q1ad3CnS3K80t6+5JcH2G5huBcccFUL2oPSf6b0tq+jVvuokyN0WYjnQ+T         drLkZadw5wQeCC3LYS7r23eRpzWzUsOFe1Nt206j8GYrn7evTnyru0vb2NPCZqDoW1Wc         9sLQ==
To: cygwin AT cygwin DOT com
From: =?UTF-8?B?UGV0ciBTa2/EjcOtaw==?= <pskocik AT gmail DOT com>
Subject: uc_sigmask set in a sigaction signal handler not honored
Message-ID: <366918d8-b505-45be-dc28-303579f17341@gmail.com>
Date: Wed, 3 Apr 2019 11:27:56 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit

Hi. Correct me if I'm wrong but POSIX appears to define

https://pubs.opengroup.org/onlinepubs/7908799/xsh/ucontext.h.html

as, among other things, containing the field:

sigset_t    uc_sigmask  the set of signals that are blocked when this
                        context is active

and it also specifies that the third argument to a .sa_sigaction
signal handler is a ucontext_t* cast to void*.

So it should follow that doing

void act(int Sig, siginfo_t *Info, void *Uctx)
{
	ucontext_t *uctx = Uctx;
	sigfillset(&uctx->uc_sigmask);
}

from a signal handler should alter the signal mask of the thread the
signal ran on.

This is how Linux and MacOS behave, but not CygWin, as the following
program shows:

#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/time.h>
void prmask(void)
{
	sigset_t mask; pthread_sigmask(SIG_SETMASK,0,&mask);
	for(int i=1; i<=64; i++){ printf("%d", sigismember(&mask,i)); } puts("");
}
void act(int Sig, siginfo_t *Info, void *Uctx)
{
	ucontext_t *uctx = Uctx;
	sigfillset(&uctx->uc_sigmask);
}
int main()
{
	struct sigaction sa;
	sa.sa_sigaction = act;
	sa.sa_flags = SA_SIGINFO;
	sigfillset(&sa.sa_mask);

	prmask();
	sigaction(SIGINT,&sa,0);
	sigaction(SIGALRM,&sa,0);
	if(1)
		setitimer(ITIMER_REAL,&(struct itimerval){.it_value={.tv_usec=10000}},0);
	pause();
	prmask();
}

I think this is a bug, so I'm reporting it. Do you think it can be fixed
in the near future?

Best regards,
Petr Skocik


--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple