1/*
2   Unix SMB/CIFS implementation.
3   signal handling functions
4
5   Copyright (C) Andrew Tridgell 1998
6
7   This program is free software; you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by
9   the Free Software Foundation; either version 3 of the License, or
10   (at your option) any later version.
11
12   This program is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   GNU General Public License for more details.
16
17   You should have received a copy of the GNU General Public License
18   along with this program.  If not, see <http://www.gnu.org/licenses/>.
19*/
20
21#include "includes.h"
22#include "system/wait.h"
23
24/**
25 * @file
26 * @brief Signal handling
27 */
28
29/****************************************************************************
30 Catch child exits and reap the child zombie status.
31****************************************************************************/
32
33static void sig_cld(int signum)
34{
35	while (waitpid((pid_t)-1,(int *)NULL, WNOHANG) > 0)
36		;
37
38	/*
39	 * Turns out it's *really* important not to
40	 * restore the signal handler here if we have real POSIX
41	 * signal handling. If we do, then we get the signal re-delivered
42	 * immediately - hey presto - instant loop ! JRA.
43	 */
44
45#if !defined(HAVE_SIGACTION)
46	CatchSignal(SIGCLD, sig_cld);
47#endif
48}
49
50/****************************************************************************
51catch child exits - leave status;
52****************************************************************************/
53
54static void sig_cld_leave_status(int signum)
55{
56	/*
57	 * Turns out it's *really* important not to
58	 * restore the signal handler here if we have real POSIX
59	 * signal handling. If we do, then we get the signal re-delivered
60	 * immediately - hey presto - instant loop ! JRA.
61	 */
62
63#if !defined(HAVE_SIGACTION)
64	CatchSignal(SIGCLD, sig_cld_leave_status);
65#endif
66}
67
68/**
69 Block sigs.
70**/
71
72void BlockSignals(bool block, int signum)
73{
74#ifdef HAVE_SIGPROCMASK
75	sigset_t set;
76	sigemptyset(&set);
77	sigaddset(&set,signum);
78	sigprocmask(block?SIG_BLOCK:SIG_UNBLOCK,&set,NULL);
79#elif defined(HAVE_SIGBLOCK)
80	if (block) {
81		sigblock(sigmask(signum));
82	} else {
83		sigsetmask(siggetmask() & ~sigmask(signum));
84	}
85#else
86	/* yikes! This platform can't block signals? */
87	static int done;
88	if (!done) {
89		DEBUG(0,("WARNING: No signal blocking available\n"));
90		done=1;
91	}
92#endif
93}
94
95/**
96 Catch a signal. This should implement the following semantics:
97
98 1) The handler remains installed after being called.
99 2) The signal should be blocked during handler execution.
100**/
101
102void (*CatchSignal(int signum,void (*handler)(int )))(int)
103{
104#ifdef HAVE_SIGACTION
105	struct sigaction act;
106	struct sigaction oldact;
107
108	ZERO_STRUCT(act);
109
110	act.sa_handler = handler;
111#ifdef SA_RESTART
112	/*
113	 * We *want* SIGALRM to interrupt a system call.
114	 */
115	if(signum != SIGALRM)
116		act.sa_flags = SA_RESTART;
117#endif
118	sigemptyset(&act.sa_mask);
119	sigaddset(&act.sa_mask,signum);
120	sigaction(signum,&act,&oldact);
121	return oldact.sa_handler;
122#else /* !HAVE_SIGACTION */
123	/* FIXME: need to handle sigvec and systems with broken signal() */
124	return signal(signum, handler);
125#endif
126}
127
128/**
129 Ignore SIGCLD via whatever means is necessary for this OS.
130**/
131
132void CatchChild(void)
133{
134	CatchSignal(SIGCLD, sig_cld);
135}
136
137/**
138 Catch SIGCLD but leave the child around so it's status can be reaped.
139**/
140
141void CatchChildLeaveStatus(void)
142{
143	CatchSignal(SIGCLD, sig_cld_leave_status);
144}
145