1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <signal.h> 30 #include <string.h> 31 32 sighandler_t sigset(int sig, sighandler_t disp) { 33 struct sigaction new_sa; 34 if (disp != SIG_HOLD) { 35 memset(&new_sa, 0, sizeof(new_sa)); 36 new_sa.sa_handler = disp; 37 sigemptyset(&new_sa.sa_mask); 38 } 39 40 struct sigaction old_sa; 41 if (sigaction(sig, disp == SIG_HOLD ? nullptr : &new_sa, &old_sa) == -1) { 42 return SIG_ERR; 43 } 44 45 sigset_t new_proc_mask; 46 sigemptyset(&new_proc_mask); 47 sigaddset(&new_proc_mask, sig); 48 49 sigset_t old_proc_mask; 50 if (sigprocmask(disp == SIG_HOLD ? SIG_BLOCK : SIG_UNBLOCK, 51 &new_proc_mask, &old_proc_mask) == -1) { 52 return SIG_ERR; 53 } 54 55 return sigismember(&old_proc_mask, sig) ? SIG_HOLD : old_sa.sa_handler; 56 } 57
