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1 | /* | |
2 | * IRC - Internet Relay Chat, ircd/ircd_signal.c | |
3 | * Copyright (C) 1990 Jarkko Oikarinen and | |
4 | * University of Oulu, Computing Center | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 1, or (at your option) | |
9 | * any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write to the Free Software | |
18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
19 | */ | |
20 | /** @file | |
21 | * @brief Signal handlers for ircu. | |
22 | * @version $Id: ircd_signal.c,v 1.6.2.2 2006/03/25 03:46:56 entrope Exp $ | |
23 | */ | |
24 | #include "config.h" | |
25 | ||
26 | #include "ircd.h" | |
27 | #include "ircd_alloc.h" | |
28 | #include "ircd_events.h" | |
29 | #include "ircd_log.h" | |
30 | #include "ircd_signal.h" | |
31 | #include "s_conf.h" | |
32 | ||
33 | /* #include <assert.h> -- Now using assert in ircd_log.h */ | |
34 | #include <signal.h> | |
35 | #include <string.h> | |
36 | #include <sys/wait.h> | |
37 | #include <unistd.h> | |
38 | ||
39 | /** Records a function to be called when a child process terminates. */ | |
40 | struct ChildRecord { | |
41 | struct ChildRecord *next; | |
42 | SigChldCallBack call; | |
43 | void *datum; | |
44 | pid_t cpid; | |
45 | }; | |
46 | ||
47 | /** Counts various types of signals that we receive. */ | |
48 | static struct tag_SignalCounter { | |
49 | unsigned int alrm; /**< Received SIGALRM count. */ | |
50 | unsigned int hup; /**< Received SIGHUP count. */ | |
51 | unsigned int chld; /**< Received SIGCHLD count. */ | |
52 | } SignalCounter; | |
53 | ||
54 | /** Event generator for SIGHUP. */ | |
55 | static struct Signal sig_hup; | |
56 | /** Event generator for SIGINT. */ | |
57 | static struct Signal sig_int; | |
58 | /** Event generator for SIGTERM. */ | |
59 | static struct Signal sig_term; | |
60 | /** Event generator for SIGCHLD. */ | |
61 | static struct Signal sig_chld; | |
62 | /** List of active child process callback requests. */ | |
63 | static struct ChildRecord *children; | |
64 | /** List of inactive (free) child records. */ | |
65 | static struct ChildRecord *crec_freelist; | |
66 | ||
67 | /* Make sure we have a definition for SIGCHLD. */ | |
68 | #if !defined(SIGCHLD) | |
69 | # define SIGCHLD SIGCLD | |
70 | #endif | |
71 | ||
72 | /** Signal handler for SIGALRM. | |
73 | * @param[in] sig Signal number (ignored). | |
74 | */ | |
75 | static void sigalrm_handler(int sig) | |
76 | { | |
77 | ++SignalCounter.alrm; | |
78 | } | |
79 | ||
80 | /** Signal callback for SIGTERM. | |
81 | * @param[in] ev Signal event descriptor. | |
82 | */ | |
83 | static void sigterm_callback(struct Event* ev) | |
84 | { | |
85 | assert(0 != ev_signal(ev)); | |
86 | assert(ET_SIGNAL == ev_type(ev)); | |
87 | assert(SIGTERM == sig_signal(ev_signal(ev))); | |
88 | assert(SIGTERM == ev_data(ev)); | |
89 | ||
90 | server_die("received signal SIGTERM"); | |
91 | } | |
92 | ||
93 | /** Signal callback for SIGHUP. | |
94 | * @param[in] ev Signal event descriptor. | |
95 | */ | |
96 | static void sighup_callback(struct Event* ev) | |
97 | { | |
98 | assert(0 != ev_signal(ev)); | |
99 | assert(ET_SIGNAL == ev_type(ev)); | |
100 | assert(SIGHUP == sig_signal(ev_signal(ev))); | |
101 | assert(SIGHUP == ev_data(ev)); | |
102 | ||
103 | ++SignalCounter.hup; | |
104 | rehash(&me, 1); | |
105 | } | |
106 | ||
107 | /** Signal callback for SIGINT. | |
108 | * @param[in] ev Signal event descriptor. | |
109 | */ | |
110 | static void sigint_callback(struct Event* ev) | |
111 | { | |
112 | assert(0 != ev_signal(ev)); | |
113 | assert(ET_SIGNAL == ev_type(ev)); | |
114 | assert(SIGINT == sig_signal(ev_signal(ev))); | |
115 | assert(SIGINT == ev_data(ev)); | |
116 | ||
117 | server_restart("caught signal: SIGINT"); | |
118 | } | |
119 | ||
120 | /** Allocate a child callback record. | |
121 | * @return Newly allocated callback record. | |
122 | */ | |
123 | static struct ChildRecord *alloc_crec(void) | |
124 | { | |
125 | struct ChildRecord *crec; | |
126 | ||
127 | if (crec_freelist) | |
128 | { | |
129 | crec = crec_freelist; | |
130 | crec_freelist = crec->next; | |
131 | } | |
132 | else | |
133 | { | |
134 | crec = MyCalloc(1, sizeof(*crec)); | |
135 | } | |
136 | ||
137 | memset(crec, 0, sizeof(*crec)); | |
138 | crec->next = NULL; | |
139 | return crec; | |
140 | } | |
141 | ||
142 | /** Release \a crec, which is after \a prev. | |
143 | * @param[in] crec Child process callback record to release. | |
144 | */ | |
145 | static void release_crec(struct ChildRecord *crec) | |
146 | { | |
147 | memset(crec, 0, sizeof(*crec)); | |
148 | crec->next = crec_freelist; | |
149 | crec_freelist = crec; | |
150 | } | |
151 | ||
152 | /** Register a function to be called when a child process terminates. | |
153 | * @param[in] child Child process ID. | |
154 | * @param[in] call Function to call when process \a child terminates. | |
155 | * @param[in] datum Additional data parameter to pass to \a call. | |
156 | */ | |
157 | void register_child(pid_t child, SigChldCallBack call, void *datum) | |
158 | { | |
159 | struct ChildRecord *crec; | |
160 | ||
161 | crec = alloc_crec(); | |
162 | /* Link into #children list. */ | |
163 | crec->next = children; | |
164 | children = crec; | |
165 | /* Fill in user fields. */ | |
166 | crec->call = call; | |
167 | crec->datum = datum; | |
168 | crec->cpid = child; | |
169 | } | |
170 | ||
171 | /** Unregister all callbacks for a child process, optionally calling | |
172 | * them first. | |
173 | * @param[in] child Child process ID to unregister. | |
174 | * @param[in] do_call If non-zero, make the callbacks. | |
175 | * @param[in] status If \a do_call is non-zero, the child's exit status. | |
176 | */ | |
177 | static void do_unregister_child(pid_t child, int do_call, int status) | |
178 | { | |
179 | struct ChildRecord *crec = children; | |
180 | struct ChildRecord *prev = NULL; | |
181 | ||
182 | while (crec != NULL) | |
183 | { | |
184 | if (crec->cpid == child) | |
185 | { | |
186 | if (do_call) | |
187 | crec->call(child, crec->datum, status); | |
188 | ||
189 | if (prev) | |
190 | prev->next = crec->next; | |
191 | else | |
192 | children = crec->next; | |
193 | ||
194 | release_crec(crec); | |
195 | } | |
196 | else | |
197 | prev = crec; | |
198 | crec = prev ? prev->next : children; | |
199 | } | |
200 | } | |
201 | ||
202 | /** Unregister all callbacks for a child process. | |
203 | * @param[in] child Child process ID to unregister. | |
204 | */ | |
205 | void unregister_child(pid_t child) | |
206 | { | |
207 | do_unregister_child(child, 0, 0); | |
208 | } | |
209 | ||
210 | /** Signal handler for SIGCHLD. | |
211 | * @param[in] ev Signal event descriptor. | |
212 | */ | |
213 | static void sigchld_callback(struct Event *ev) | |
214 | { | |
215 | pid_t cpid; | |
216 | int status; | |
217 | ||
218 | ++SignalCounter.chld; | |
219 | do { | |
220 | cpid = waitpid(-1, &status, WNOHANG); | |
221 | if (cpid > 0) | |
222 | do_unregister_child(cpid, 1, status); | |
223 | } while (cpid > 0); | |
224 | } | |
225 | ||
226 | /** Register all necessary signal handlers. */ | |
227 | void setup_signals(void) | |
228 | { | |
229 | struct sigaction act; | |
230 | ||
231 | act.sa_handler = SIG_IGN; | |
232 | act.sa_flags = 0; | |
233 | sigemptyset(&act.sa_mask); | |
234 | sigaddset(&act.sa_mask, SIGPIPE); | |
235 | sigaddset(&act.sa_mask, SIGALRM); | |
236 | #ifdef SIGWINCH | |
237 | sigaddset(&act.sa_mask, SIGWINCH); | |
238 | sigaction(SIGWINCH, &act, 0); | |
239 | #endif | |
240 | sigaction(SIGPIPE, &act, 0); | |
241 | ||
242 | act.sa_handler = sigalrm_handler; | |
243 | sigaction(SIGALRM, &act, 0); | |
244 | ||
245 | signal_add(&sig_hup, sighup_callback, 0, SIGHUP); | |
246 | signal_add(&sig_int, sigint_callback, 0, SIGINT); | |
247 | signal_add(&sig_term, sigterm_callback, 0, SIGTERM); | |
248 | signal_add(&sig_chld, sigchld_callback, 0, SIGCHLD); | |
249 | ||
250 | #ifdef HAVE_RESTARTABLE_SYSCALLS | |
251 | /* | |
252 | * At least on Apollo sr10.1 it seems continuing system calls | |
253 | * after signal is the default. The following 'siginterrupt' | |
254 | * should change that default to interrupting calls. | |
255 | */ | |
256 | siginterrupt(SIGALRM, 1); | |
257 | #endif | |
258 | } | |
259 | ||
260 | /** Kill and clean up all child processes. */ | |
261 | void reap_children(void) | |
262 | { | |
263 | /* Send SIGTERM to all children in process group. Sleep for a | |
264 | * second to let them exit before we try to clean them up. | |
265 | */ | |
266 | kill(0, SIGTERM); | |
267 | sleep(1); | |
268 | sigchld_callback(NULL); | |
269 | } |