xref: /openbsd-src/usr.bin/tmux/proc.c (revision a0747c9f67a4ae71ccb71e62a28d1ea19e06a63c) 
1 /* $OpenBSD: proc.c,v 1.20 2021/02/11 09:39:29 nicm Exp $ */
2 
3 /*
4  * Copyright (c) 2015 Nicholas Marriott <nicholas.marriott@gmail.com>
5  *
6  * Permission to use, copy, modify, and distribute this software for any
7  * purpose with or without fee is hereby granted, provided that the above
8  * copyright notice and this permission notice appear in all copies.
9  *
10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14  * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
15  * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
16  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17  */
18 
19 #include <sys/types.h>
20 #include <sys/queue.h>
21 #include <sys/socket.h>
22 #include <sys/uio.h>
23 #include <sys/utsname.h>
24 
25 #include <errno.h>
26 #include <event.h>
27 #include <imsg.h>
28 #include <signal.h>
29 #include <stdlib.h>
30 #include <string.h>
31 #include <unistd.h>
32 
33 #include "tmux.h"
34 
35 struct tmuxproc {
36 	const char	 *name;
37 	int		  exit;
38 
39 	void		(*signalcb)(int);
40 
41 	struct event	  ev_sigint;
42 	struct event	  ev_sighup;
43 	struct event	  ev_sigchld;
44 	struct event	  ev_sigcont;
45 	struct event	  ev_sigterm;
46 	struct event	  ev_sigusr1;
47 	struct event	  ev_sigusr2;
48 	struct event	  ev_sigwinch;
49 
50 	TAILQ_HEAD(, tmuxpeer) peers;
51 };
52 
53 struct tmuxpeer {
54 	struct tmuxproc	*parent;
55 
56 	struct imsgbuf	 ibuf;
57 	struct event	 event;
58 
59 	int		 flags;
60 #define PEER_BAD 0x1
61 
62 	void		(*dispatchcb)(struct imsg *, void *);
63 	void		 *arg;
64 
65 	TAILQ_ENTRY(tmuxpeer) entry;
66 };
67 
68 static int	peer_check_version(struct tmuxpeer *, struct imsg *);
69 static void	proc_update_event(struct tmuxpeer *);
70 
71 static void
72 proc_event_cb(__unused int fd, short events, void *arg)
73 {
74 	struct tmuxpeer	*peer = arg;
75 	ssize_t		 n;
76 	struct imsg	 imsg;
77 
78 	if (!(peer->flags & PEER_BAD) && (events & EV_READ)) {
79 		if (((n = imsg_read(&peer->ibuf)) == -1 && errno != EAGAIN) ||
80 		    n == 0) {
81 			peer->dispatchcb(NULL, peer->arg);
82 			return;
83 		}
84 		for (;;) {
85 			if ((n = imsg_get(&peer->ibuf, &imsg)) == -1) {
86 				peer->dispatchcb(NULL, peer->arg);
87 				return;
88 			}
89 			if (n == 0)
90 				break;
91 			log_debug("peer %p message %d", peer, imsg.hdr.type);
92 
93 			if (peer_check_version(peer, &imsg) != 0) {
94 				if (imsg.fd != -1)
95 					close(imsg.fd);
96 				imsg_free(&imsg);
97 				break;
98 			}
99 
100 			peer->dispatchcb(&imsg, peer->arg);
101 			imsg_free(&imsg);
102 		}
103 	}
104 
105 	if (events & EV_WRITE) {
106 		if (msgbuf_write(&peer->ibuf.w) <= 0 && errno != EAGAIN) {
107 			peer->dispatchcb(NULL, peer->arg);
108 			return;
109 		}
110 	}
111 
112 	if ((peer->flags & PEER_BAD) && peer->ibuf.w.queued == 0) {
113 		peer->dispatchcb(NULL, peer->arg);
114 		return;
115 	}
116 
117 	proc_update_event(peer);
118 }
119 
120 static void
121 proc_signal_cb(int signo, __unused short events, void *arg)
122 {
123 	struct tmuxproc	*tp = arg;
124 
125 	tp->signalcb(signo);
126 }
127 
128 static int
129 peer_check_version(struct tmuxpeer *peer, struct imsg *imsg)
130 {
131 	int	version;
132 
133 	version = imsg->hdr.peerid & 0xff;
134 	if (imsg->hdr.type != MSG_VERSION && version != PROTOCOL_VERSION) {
135 		log_debug("peer %p bad version %d", peer, version);
136 
137 		proc_send(peer, MSG_VERSION, -1, NULL, 0);
138 		peer->flags |= PEER_BAD;
139 
140 		return (-1);
141 	}
142 	return (0);
143 }
144 
145 static void
146 proc_update_event(struct tmuxpeer *peer)
147 {
148 	short	events;
149 
150 	event_del(&peer->event);
151 
152 	events = EV_READ;
153 	if (peer->ibuf.w.queued > 0)
154 		events |= EV_WRITE;
155 	event_set(&peer->event, peer->ibuf.fd, events, proc_event_cb, peer);
156 
157 	event_add(&peer->event, NULL);
158 }
159 
160 int
161 proc_send(struct tmuxpeer *peer, enum msgtype type, int fd, const void *buf,
162     size_t len)
163 {
164 	struct imsgbuf	*ibuf = &peer->ibuf;
165 	void		*vp = (void *)buf;
166 	int		 retval;
167 
168 	if (peer->flags & PEER_BAD)
169 		return (-1);
170 	log_debug("sending message %d to peer %p (%zu bytes)", type, peer, len);
171 
172 	retval = imsg_compose(ibuf, type, PROTOCOL_VERSION, -1, fd, vp, len);
173 	if (retval != 1)
174 		return (-1);
175 	proc_update_event(peer);
176 	return (0);
177 }
178 
179 struct tmuxproc *
180 proc_start(const char *name)
181 {
182 	struct tmuxproc	*tp;
183 	struct utsname	 u;
184 
185 	log_open(name);
186 	setproctitle("%s (%s)", name, socket_path);
187 
188 	if (uname(&u) < 0)
189 		memset(&u, 0, sizeof u);
190 
191 	log_debug("%s started (%ld): version %s, socket %s, protocol %d", name,
192 	    (long)getpid(), getversion(), socket_path, PROTOCOL_VERSION);
193 	log_debug("on %s %s %s; libevent %s (%s)", u.sysname, u.release,
194 	    u.version, event_get_version(), event_get_method());
195 
196 	tp = xcalloc(1, sizeof *tp);
197 	tp->name = xstrdup(name);
198 	TAILQ_INIT(&tp->peers);
199 
200 	return (tp);
201 }
202 
203 void
204 proc_loop(struct tmuxproc *tp, int (*loopcb)(void))
205 {
206 	log_debug("%s loop enter", tp->name);
207 	do
208 		event_loop(EVLOOP_ONCE);
209 	while (!tp->exit && (loopcb == NULL || !loopcb ()));
210 	log_debug("%s loop exit", tp->name);
211 }
212 
213 void
214 proc_exit(struct tmuxproc *tp)
215 {
216 	struct tmuxpeer	*peer;
217 
218 	TAILQ_FOREACH(peer, &tp->peers, entry)
219 	    imsg_flush(&peer->ibuf);
220 	tp->exit = 1;
221 }
222 
223 void
224 proc_set_signals(struct tmuxproc *tp, void (*signalcb)(int))
225 {
226 	struct sigaction	sa;
227 
228 	tp->signalcb = signalcb;
229 
230 	memset(&sa, 0, sizeof sa);
231 	sigemptyset(&sa.sa_mask);
232 	sa.sa_flags = SA_RESTART;
233 	sa.sa_handler = SIG_IGN;
234 
235 	sigaction(SIGPIPE, &sa, NULL);
236 	sigaction(SIGTSTP, &sa, NULL);
237 	sigaction(SIGTTIN, &sa, NULL);
238 	sigaction(SIGTTOU, &sa, NULL);
239 	sigaction(SIGQUIT, &sa, NULL);
240 
241 	signal_set(&tp->ev_sigint, SIGINT, proc_signal_cb, tp);
242 	signal_add(&tp->ev_sigint, NULL);
243 	signal_set(&tp->ev_sighup, SIGHUP, proc_signal_cb, tp);
244 	signal_add(&tp->ev_sighup, NULL);
245 	signal_set(&tp->ev_sigchld, SIGCHLD, proc_signal_cb, tp);
246 	signal_add(&tp->ev_sigchld, NULL);
247 	signal_set(&tp->ev_sigcont, SIGCONT, proc_signal_cb, tp);
248 	signal_add(&tp->ev_sigcont, NULL);
249 	signal_set(&tp->ev_sigterm, SIGTERM, proc_signal_cb, tp);
250 	signal_add(&tp->ev_sigterm, NULL);
251 	signal_set(&tp->ev_sigusr1, SIGUSR1, proc_signal_cb, tp);
252 	signal_add(&tp->ev_sigusr1, NULL);
253 	signal_set(&tp->ev_sigusr2, SIGUSR2, proc_signal_cb, tp);
254 	signal_add(&tp->ev_sigusr2, NULL);
255 	signal_set(&tp->ev_sigwinch, SIGWINCH, proc_signal_cb, tp);
256 	signal_add(&tp->ev_sigwinch, NULL);
257 }
258 
259 void
260 proc_clear_signals(struct tmuxproc *tp, int defaults)
261 {
262 	struct sigaction	sa;
263 
264 	memset(&sa, 0, sizeof sa);
265 	sigemptyset(&sa.sa_mask);
266 	sa.sa_flags = SA_RESTART;
267 	sa.sa_handler = SIG_DFL;
268 
269 	sigaction(SIGPIPE, &sa, NULL);
270 	sigaction(SIGTSTP, &sa, NULL);
271 
272 	signal_del(&tp->ev_sigint);
273 	signal_del(&tp->ev_sighup);
274 	signal_del(&tp->ev_sigchld);
275 	signal_del(&tp->ev_sigcont);
276 	signal_del(&tp->ev_sigterm);
277 	signal_del(&tp->ev_sigusr1);
278 	signal_del(&tp->ev_sigusr2);
279 	signal_del(&tp->ev_sigwinch);
280 
281 	if (defaults) {
282 		sigaction(SIGINT, &sa, NULL);
283 		sigaction(SIGQUIT, &sa, NULL);
284 		sigaction(SIGHUP, &sa, NULL);
285 		sigaction(SIGCHLD, &sa, NULL);
286 		sigaction(SIGCONT, &sa, NULL);
287 		sigaction(SIGTERM, &sa, NULL);
288 		sigaction(SIGUSR1, &sa, NULL);
289 		sigaction(SIGUSR2, &sa, NULL);
290 		sigaction(SIGWINCH, &sa, NULL);
291 	}
292 }
293 
294 struct tmuxpeer *
295 proc_add_peer(struct tmuxproc *tp, int fd,
296     void (*dispatchcb)(struct imsg *, void *), void *arg)
297 {
298 	struct tmuxpeer	*peer;
299 
300 	peer = xcalloc(1, sizeof *peer);
301 	peer->parent = tp;
302 
303 	peer->dispatchcb = dispatchcb;
304 	peer->arg = arg;
305 
306 	imsg_init(&peer->ibuf, fd);
307 	event_set(&peer->event, fd, EV_READ, proc_event_cb, peer);
308 
309 	log_debug("add peer %p: %d (%p)", peer, fd, arg);
310 	TAILQ_INSERT_TAIL(&tp->peers, peer, entry);
311 
312 	proc_update_event(peer);
313 	return (peer);
314 }
315 
316 void
317 proc_remove_peer(struct tmuxpeer *peer)
318 {
319 	TAILQ_REMOVE(&peer->parent->peers, peer, entry);
320 	log_debug("remove peer %p", peer);
321 
322 	event_del(&peer->event);
323 	imsg_clear(&peer->ibuf);
324 
325 	close(peer->ibuf.fd);
326 	free(peer);
327 }
328 
329 void
330 proc_kill_peer(struct tmuxpeer *peer)
331 {
332 	peer->flags |= PEER_BAD;
333 }
334 
335 void
336 proc_toggle_log(struct tmuxproc *tp)
337 {
338 	log_toggle(tp->name);
339 }
340 
341 pid_t
342 proc_fork_and_daemon(int *fd)
343 {
344 	pid_t	pid;
345 	int	pair[2];
346 
347 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pair) != 0)
348 		fatal("socketpair failed");
349 	switch (pid = fork()) {
350 	case -1:
351 		fatal("fork failed");
352 	case 0:
353 		close(pair[0]);
354 		*fd = pair[1];
355 		if (daemon(1, 0) != 0)
356 			fatal("daemon failed");
357 		return (0);
358 	default:
359 		close(pair[1]);
360 		*fd = pair[0];
361 		return (pid);
362 	}
363 }
364