xref: /openbsd/usr.bin/tmux/tmux.c (revision 3cab2bb3) 
1 /* $OpenBSD: tmux.c,v 1.202 2020/06/02 08:17:27 nicm Exp $ */
2 
3 /*
4  * Copyright (c) 2007 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/stat.h>
21 #include <sys/utsname.h>
22 
23 #include <err.h>
24 #include <errno.h>
25 #include <event.h>
26 #include <fcntl.h>
27 #include <langinfo.h>
28 #include <locale.h>
29 #include <paths.h>
30 #include <pwd.h>
31 #include <signal.h>
32 #include <stdlib.h>
33 #include <string.h>
34 #include <time.h>
35 #include <unistd.h>
36 #include <util.h>
37 
38 #include "tmux.h"
39 
40 struct options	*global_options;	/* server options */
41 struct options	*global_s_options;	/* session options */
42 struct options	*global_w_options;	/* window options */
43 struct environ	*global_environ;
44 
45 struct timeval	 start_time;
46 const char	*socket_path;
47 int		 ptm_fd = -1;
48 const char	*shell_command;
49 
50 static __dead void	 usage(void);
51 static char		*make_label(const char *, char **);
52 
53 static int		 areshell(const char *);
54 static const char	*getshell(void);
55 
56 static __dead void
57 usage(void)
58 {
59 	fprintf(stderr,
60 	    "usage: %s [-2CDluvV] [-c shell-command] [-f file] [-L socket-name]\n"
61 	    "            [-S socket-path] [-T features] [command [flags]]\n",
62 	    getprogname());
63 	exit(1);
64 }
65 
66 static const char *
67 getshell(void)
68 {
69 	struct passwd	*pw;
70 	const char	*shell;
71 
72 	shell = getenv("SHELL");
73 	if (checkshell(shell))
74 		return (shell);
75 
76 	pw = getpwuid(getuid());
77 	if (pw != NULL && checkshell(pw->pw_shell))
78 		return (pw->pw_shell);
79 
80 	return (_PATH_BSHELL);
81 }
82 
83 int
84 checkshell(const char *shell)
85 {
86 	if (shell == NULL || *shell != '/')
87 		return (0);
88 	if (areshell(shell))
89 		return (0);
90 	if (access(shell, X_OK) != 0)
91 		return (0);
92 	return (1);
93 }
94 
95 static int
96 areshell(const char *shell)
97 {
98 	const char	*progname, *ptr;
99 
100 	if ((ptr = strrchr(shell, '/')) != NULL)
101 		ptr++;
102 	else
103 		ptr = shell;
104 	progname = getprogname();
105 	if (*progname == '-')
106 		progname++;
107 	if (strcmp(ptr, progname) == 0)
108 		return (1);
109 	return (0);
110 }
111 
112 static char *
113 expand_path(const char *path, const char *home)
114 {
115 	char			*expanded, *name;
116 	const char		*end;
117 	struct environ_entry	*value;
118 
119 	if (strncmp(path, "~/", 2) == 0) {
120 		if (home == NULL)
121 			return (NULL);
122 		xasprintf(&expanded, "%s%s", home, path + 1);
123 		return (expanded);
124 	}
125 
126 	if (*path == '$') {
127 		end = strchr(path, '/');
128 		if (end == NULL)
129 			name = xstrdup(path + 1);
130 		else
131 			name = xstrndup(path + 1, end - path - 1);
132 		value = environ_find(global_environ, name);
133 		free(name);
134 		if (value == NULL)
135 			return (NULL);
136 		if (end == NULL)
137 			end = "";
138 		xasprintf(&expanded, "%s%s", value->value, end);
139 		return (expanded);
140 	}
141 
142 	return (xstrdup(path));
143 }
144 
145 void
146 expand_paths(const char *s, char ***paths, u_int *n)
147 {
148 	const char	*home = find_home();
149 	char		*copy, *next, *tmp, resolved[PATH_MAX], *expanded;
150 	u_int		 i;
151 
152 	*paths = NULL;
153 	*n = 0;
154 
155 	copy = tmp = xstrdup(s);
156 	while ((next = strsep(&tmp, ":")) != NULL) {
157 		expanded = expand_path(next, home);
158 		if (expanded == NULL) {
159 			log_debug("%s: invalid path: %s", __func__, next);
160 			continue;
161 		}
162 		if (realpath(expanded, resolved) == NULL) {
163 			log_debug("%s: realpath(\"%s\") failed: %s", __func__,
164 			    expanded, strerror(errno));
165 			free(expanded);
166 			continue;
167 		}
168 		free(expanded);
169 		for (i = 0; i < *n; i++) {
170 			if (strcmp(resolved, (*paths)[i]) == 0)
171 				break;
172 		}
173 		if (i != *n) {
174 			log_debug("%s: duplicate path: %s", __func__, resolved);
175 			continue;
176 		}
177 		*paths = xreallocarray(*paths, (*n) + 1, sizeof *paths);
178 		(*paths)[(*n)++] = xstrdup(resolved);
179 	}
180 	free(copy);
181 }
182 
183 static char *
184 make_label(const char *label, char **cause)
185 {
186 	char		**paths, *path, *base;
187 	u_int		  i, n;
188 	struct stat	  sb;
189 	uid_t		  uid;
190 
191 	*cause = NULL;
192 	if (label == NULL)
193 		label = "default";
194 	uid = getuid();
195 
196 	expand_paths(TMUX_SOCK, &paths, &n);
197 	if (n == 0) {
198 		xasprintf(cause, "no suitable socket path");
199 		return (NULL);
200 	}
201 	path = paths[0]; /* can only have one socket! */
202 	for (i = 1; i < n; i++)
203 		free(paths[i]);
204 	free(paths);
205 
206 	xasprintf(&base, "%s/tmux-%ld", path, (long)uid);
207 	if (mkdir(base, S_IRWXU) != 0 && errno != EEXIST)
208 		goto fail;
209 	if (lstat(base, &sb) != 0)
210 		goto fail;
211 	if (!S_ISDIR(sb.st_mode)) {
212 		errno = ENOTDIR;
213 		goto fail;
214 	}
215 	if (sb.st_uid != uid || (sb.st_mode & S_IRWXO) != 0) {
216 		errno = EACCES;
217 		goto fail;
218 	}
219 	xasprintf(&path, "%s/%s", base, label);
220 	free(base);
221 	return (path);
222 
223 fail:
224 	xasprintf(cause, "error creating %s (%s)", base, strerror(errno));
225 	free(base);
226 	return (NULL);
227 }
228 
229 void
230 setblocking(int fd, int state)
231 {
232 	int mode;
233 
234 	if ((mode = fcntl(fd, F_GETFL)) != -1) {
235 		if (!state)
236 			mode |= O_NONBLOCK;
237 		else
238 			mode &= ~O_NONBLOCK;
239 		fcntl(fd, F_SETFL, mode);
240 	}
241 }
242 
243 uint64_t
244 get_timer(void)
245 {
246 	struct timespec	ts;
247 
248 	/*
249 	 * We want a timestamp in milliseconds suitable for time measurement,
250 	 * so prefer the monotonic clock.
251 	 */
252 	if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
253 		clock_gettime(CLOCK_REALTIME, &ts);
254 	return ((ts.tv_sec * 1000ULL) + (ts.tv_nsec / 1000000ULL));
255 }
256 
257 const char *
258 sig2name(int signo)
259 {
260      static char	s[11];
261 
262      if (signo > 0 && signo < NSIG)
263 	     return (sys_signame[signo]);
264      xsnprintf(s, sizeof s, "%d", signo);
265      return (s);
266 }
267 
268 const char *
269 find_cwd(void)
270 {
271 	char		 resolved1[PATH_MAX], resolved2[PATH_MAX];
272 	static char	 cwd[PATH_MAX];
273 	const char	*pwd;
274 
275 	if (getcwd(cwd, sizeof cwd) == NULL)
276 		return (NULL);
277 	if ((pwd = getenv("PWD")) == NULL || *pwd == '\0')
278 		return (cwd);
279 
280 	/*
281 	 * We want to use PWD so that symbolic links are maintained,
282 	 * but only if it matches the actual working directory.
283 	 */
284 	if (realpath(pwd, resolved1) == NULL)
285 		return (cwd);
286 	if (realpath(cwd, resolved2) == NULL)
287 		return (cwd);
288 	if (strcmp(resolved1, resolved2) != 0)
289 		return (cwd);
290 	return (pwd);
291 }
292 
293 const char *
294 find_home(void)
295 {
296 	struct passwd		*pw;
297 	static const char	*home;
298 
299 	if (home != NULL)
300 		return (home);
301 
302 	home = getenv("HOME");
303 	if (home == NULL || *home == '\0') {
304 		pw = getpwuid(getuid());
305 		if (pw != NULL)
306 			home = pw->pw_dir;
307 		else
308 			home = NULL;
309 	}
310 
311 	return (home);
312 }
313 
314 const char *
315 getversion(void)
316 {
317 	static char	*version;
318 	struct utsname	 u;
319 
320 	if (version == NULL) {
321 		if (uname(&u) < 0)
322 			fatalx("uname failed");
323 		xasprintf(&version, "openbsd-%s", u.release);
324 	}
325 	return (version);
326 }
327 
328 int
329 main(int argc, char **argv)
330 {
331 	char					*path = NULL, *label = NULL;
332 	char					*cause, **var;
333 	const char				*s, *shell, *cwd;
334 	int					 opt, flags = 0, keys;
335 	int					 feat = 0;
336 	const struct options_table_entry	*oe;
337 
338 	if (setlocale(LC_CTYPE, "en_US.UTF-8") == NULL &&
339 	    setlocale(LC_CTYPE, "C.UTF-8") == NULL) {
340 		if (setlocale(LC_CTYPE, "") == NULL)
341 			errx(1, "invalid LC_ALL, LC_CTYPE or LANG");
342 		s = nl_langinfo(CODESET);
343 		if (strcasecmp(s, "UTF-8") != 0 && strcasecmp(s, "UTF8") != 0)
344 			errx(1, "need UTF-8 locale (LC_CTYPE) but have %s", s);
345 	}
346 
347 	setlocale(LC_TIME, "");
348 	tzset();
349 
350 	if (**argv == '-')
351 		flags = CLIENT_LOGIN;
352 
353 	while ((opt = getopt(argc, argv, "2c:CDdf:lL:qS:T:uUvV")) != -1) {
354 		switch (opt) {
355 		case '2':
356 			tty_add_features(&feat, "256", ":,");
357 			break;
358 		case 'c':
359 			shell_command = optarg;
360 			break;
361 		case 'D':
362 			flags |= CLIENT_NOFORK;
363 			break;
364 		case 'C':
365 			if (flags & CLIENT_CONTROL)
366 				flags |= CLIENT_CONTROLCONTROL;
367 			else
368 				flags |= CLIENT_CONTROL;
369 			break;
370 		case 'f':
371 			set_cfg_file(optarg);
372 			break;
373  		case 'V':
374 			printf("%s %s\n", getprogname(), getversion());
375  			exit(0);
376 		case 'l':
377 			flags |= CLIENT_LOGIN;
378 			break;
379 		case 'L':
380 			free(label);
381 			label = xstrdup(optarg);
382 			break;
383 		case 'q':
384 			break;
385 		case 'S':
386 			free(path);
387 			path = xstrdup(optarg);
388 			break;
389 		case 'T':
390 			tty_add_features(&feat, optarg, ":,");
391 			break;
392 		case 'u':
393 			flags |= CLIENT_UTF8;
394 			break;
395 		case 'v':
396 			log_add_level();
397 			break;
398 		default:
399 			usage();
400 		}
401 	}
402 	argc -= optind;
403 	argv += optind;
404 
405 	if (shell_command != NULL && argc != 0)
406 		usage();
407 	if ((flags & CLIENT_NOFORK) && argc != 0)
408 		usage();
409 
410 	if ((ptm_fd = getptmfd()) == -1)
411 		err(1, "getptmfd");
412 	if (pledge("stdio rpath wpath cpath flock fattr unix getpw sendfd "
413 	    "recvfd proc exec tty ps", NULL) != 0)
414 		err(1, "pledge");
415 
416 	/*
417 	 * tmux is a UTF-8 terminal, so if TMUX is set, assume UTF-8.
418 	 * Otherwise, if the user has set LC_ALL, LC_CTYPE or LANG to contain
419 	 * UTF-8, it is a safe assumption that either they are using a UTF-8
420 	 * terminal, or if not they know that output from UTF-8-capable
421 	 * programs may be wrong.
422 	 */
423 	if (getenv("TMUX") != NULL)
424 		flags |= CLIENT_UTF8;
425 	else {
426 		s = getenv("LC_ALL");
427 		if (s == NULL || *s == '\0')
428 			s = getenv("LC_CTYPE");
429 		if (s == NULL || *s == '\0')
430 			s = getenv("LANG");
431 		if (s == NULL || *s == '\0')
432 			s = "";
433 		if (strcasestr(s, "UTF-8") != NULL ||
434 		    strcasestr(s, "UTF8") != NULL)
435 			flags |= CLIENT_UTF8;
436 	}
437 
438 	global_environ = environ_create();
439 	for (var = environ; *var != NULL; var++)
440 		environ_put(global_environ, *var, 0);
441 	if ((cwd = find_cwd()) != NULL)
442 		environ_set(global_environ, "PWD", 0, "%s", cwd);
443 
444 	global_options = options_create(NULL);
445 	global_s_options = options_create(NULL);
446 	global_w_options = options_create(NULL);
447 	for (oe = options_table; oe->name != NULL; oe++) {
448 		if (oe->scope & OPTIONS_TABLE_SERVER)
449 			options_default(global_options, oe);
450 		if (oe->scope & OPTIONS_TABLE_SESSION)
451 			options_default(global_s_options, oe);
452 		if (oe->scope & OPTIONS_TABLE_WINDOW)
453 			options_default(global_w_options, oe);
454 	}
455 
456 	/*
457 	 * The default shell comes from SHELL or from the user's passwd entry
458 	 * if available.
459 	 */
460 	shell = getshell();
461 	options_set_string(global_s_options, "default-shell", 0, "%s", shell);
462 
463 	/* Override keys to vi if VISUAL or EDITOR are set. */
464 	if ((s = getenv("VISUAL")) != NULL || (s = getenv("EDITOR")) != NULL) {
465 		options_set_string(global_options, "editor", 0, "%s", s);
466 		if (strrchr(s, '/') != NULL)
467 			s = strrchr(s, '/') + 1;
468 		if (strstr(s, "vi") != NULL)
469 			keys = MODEKEY_VI;
470 		else
471 			keys = MODEKEY_EMACS;
472 		options_set_number(global_s_options, "status-keys", keys);
473 		options_set_number(global_w_options, "mode-keys", keys);
474 	}
475 
476 	/*
477 	 * If socket is specified on the command-line with -S or -L, it is
478 	 * used. Otherwise, $TMUX is checked and if that fails "default" is
479 	 * used.
480 	 */
481 	if (path == NULL && label == NULL) {
482 		s = getenv("TMUX");
483 		if (s != NULL && *s != '\0' && *s != ',') {
484 			path = xstrdup(s);
485 			path[strcspn(path, ",")] = '\0';
486 		}
487 	}
488 	if (path == NULL) {
489 		if ((path = make_label(label, &cause)) == NULL) {
490 			if (cause != NULL) {
491 				fprintf(stderr, "%s\n", cause);
492 				free(cause);
493 			}
494 			exit(1);
495 		}
496 		flags |= CLIENT_DEFAULTSOCKET;
497 	}
498 	socket_path = path;
499 	free(label);
500 
501 	/* Pass control to the client. */
502 	exit(client_main(event_init(), argc, argv, flags, feat));
503 }
504