/*************************************************************************\
* Copyright (C) Michael Kerrisk, 2018. *
* *
* This program is free software. You may use, modify, and redistribute it *
* under the terms of the GNU General Public License as published by the *
* Free Software Foundation, either version 3 or (at your option) any *
* later version. This program is distributed without any warranty. See *
* the file COPYING.gpl-v3 for details. *
\*************************************************************************//* Listing 22-7 *//* signalfd_sigval.cUsage: signalfd_sigval sig-num...Demonstrate the use of signalfd() to receive signals via a file descriptor.This program is Linux-specific. The signalfd API is supported since kernel2.6.22.
*/#include<sys/signalfd.h>#include<signal.h>#include"tlpi_hdr.h"intmain(int argc,char*argv[]){sigset_t mask;int sfd, j;struct signalfd_siginfo fdsi;ssize_t s;if(argc <2||strcmp(argv[1],"--help")==0)usageErr("%s sig-num...\n", argv[0]);printf("%s: PID = %ld\n", argv[0],(long)getpid());sigemptyset(&mask);for(j =1; j < argc; j++)sigaddset(&mask,atoi(argv[j]));if(sigprocmask(SIG_BLOCK,&mask,NULL)==-1)errExit("sigprocmask");sfd =signalfd(-1,&mask,0);if(sfd ==-1)errExit("signalfd");for(;;){s =read(sfd,&fdsi,sizeof(struct signalfd_siginfo));if(s !=sizeof(struct signalfd_siginfo))errExit("read");printf("%s: got signal %d", argv[0], fdsi.ssi_signo);if(fdsi.ssi_code == SI_QUEUE){printf("; ssi_pid = %d; ", fdsi.ssi_pid);printf("ssi_int = %d", fdsi.ssi_int);}printf("\n");}}
