在C，我可以说
#include <stdio.h> #include <unistd.h> #include <signal.h> int continue_running = 1; void handler(int signal,siginfo_t* info,void* data) { printf("got signal %d from process %d running as user %d\n",signal,info->si_pid,info->si_uid); continue_running = 0; } int main(int argc,char** argv) { struct sigaction sa; sigset_t mask; sigemptyset(&mask); sa.sa_sigaction = &handler; sa.sa_mask = mask; sa.sa_flags = SA_SIGINFO; sigaction(SIGTERM,&sa,NULL); printf("pid is %d\n",getpid()); while (continue_running) { sleep(1); }; return 0; }
这打印出来的东西
pid is 31980 got signal 15 from process 31985 running as user 1000
当从过程31985发送SIGTERM时。
我可以写类似的Perl 5代码使用POSIX :: sigaction：
#!/usr/bin/perl
use strict;
use warnings;
use POSIX;
use Data::Dumper;
my $sigset = POSIX::SigSet->new;
$sigset->emptyset;
my $sa = POSIX::SigAction->new(
sub { print "caught signal\n" . Dumper \@_; $a = 0 },$sigset,);
$sa->flags(POSIX::SA_SIGINFO);
$sa->safe(1); #defer the signal until we are in a safe place in the intrepeter
POSIX::sigaction(POSIX::SIGTERM,$sa);
print "$$\n";
$a = 1;
sleep 1 while $a;
但是处理程序仍然只接收一个参数(信号)。如何获得siginfo_t结构？是否必须编写自己的XS代码设置自己的处理程序，然后将信息传递到Perl回调？在XS中编写自己的处理程序在某种程度上解开了解释器？
解决方法
sighandler(在mg.c中)是Perl信号处理程序子程序的包装器。正如你可以看到，它是能够发送你想要的信息到Perl信号处理程序子。
#if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
{
struct sigaction oact;
if (sigaction(sig,&oact) == 0 && oact.sa_flags & SA_SIGINFO) {
if (sip) {
HV *sih = newHV();
SV *rv = newRV_noinc(MUTABLE_SV(sih));
/* The siginfo fields signo,code,errno,pid,uid,* addr,status,and band are defined by POSIX/SUSv3. */
(void)hv_stores(sih,"signo",newSViv(sip->si_signo));
(void)hv_stores(sih,"code",newSViv(sip->si_code));
#if 0 /* XXX TODO: Configure scan for the existence of these,but even that does not help if the SA_SIGINFO is not implemented according to the spec. */
hv_stores(sih,"errno",newSViv(sip->si_errno));
hv_stores(sih,"status",newSViv(sip->si_status));
hv_stores(sih,"uid",newSViv(sip->si_uid));
hv_stores(sih,"pid",newSViv(sip->si_pid));
hv_stores(sih,"addr",newSVuv(PTR2UV(sip->si_addr)));
hv_stores(sih,"band",newSViv(sip->si_band));
#endif
EXTEND(SP,2);
PUSHs(rv);
mPUSHp((char *)sip,sizeof(*sip));
}
}
}
}
你想要的信息将在最后一个参数，虽然你必须解压* sip自己的Perl端。抓住的是，上面的代码没有得到excercised。具体来说，sip总是NULL。
在不安全信号下，sighandler从csighandler，Perl的C级信号处理程序调用。它目前不传递相关信息给signalhandler，但这很容易修复。
-Perl_csighandler(int sig,siginfo_t *sip PERL_UNUSED_DECL,void *uap PERL_UNUSED_DECL) +Perl_csighandler(int sig,siginfo_t *sip,void *uap PERL_UNUSED_DECL) - (*PL_sighandlerp)(sig,NULL,NULL); + (*PL_sighandlerp)(sig,sip,NULL);
样品运行：
$ PERL_SIGNALS=unsafe ./perl -Ilib a.pl
31213
caught signal
$VAR1 = [
'TERM',{
'code' => 0,'signo' => 15
},'...*sip as "packed/binary" string...'
];
在安全信号下，通过PERL_ASYNC_CHECK从despatch_signals(sic)调用sigandler。不幸的是，先前由csighandler接收的* sip不再可用。要解决这个问题，csighandler必须将* sip的副本排队等待despatch_signals获取。