daemon: Improve "daemonizing" log message.
[paraslash.git] / daemon.c
1 /*
2 * Copyright (C) 1997 Andre Noll <maan@tuebingen.mpg.de>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file daemon.c Some helpers for programs that detach from the console. */
8
9 #include <regex.h>
10 #include <pwd.h>
11 #include <sys/types.h> /* getgrnam() */
12 #include <grp.h>
13 #include <signal.h>
14 #include <sys/resource.h>
15
16 #include "para.h"
17 #include "daemon.h"
18 #include "string.h"
19 #include "color.h"
20
21 /** The internal state of the daemon. */
22 struct daemon {
23 /** See \ref daemon_flags. */
24 unsigned flags;
25 /** Set by \ref daemon_set_logfile(). */
26 char *logfile_name;
27 /** Current loglevel, see \ref daemon_set_loglevel(). */
28 int loglevel;
29 /** Used by \ref server_uptime() and \ref uptime_str(). */
30 time_t startuptime;
31 /** The file pointer if the logfile is open. */
32 FILE *logfile;
33 /** Used by para_log() if \p DF_LOG_HOSTNAME is set. */
34 char *hostname;
35 /** Used for colored log messages. */
36 char log_colors[NUM_LOGLEVELS][COLOR_MAXLEN];
37 };
38
39 static struct daemon the_daemon, *me = &the_daemon;
40
41 static void daemon_set_default_log_colors(void)
42 {
43 int i;
44 static const char *default_log_colors[NUM_LOGLEVELS] = {
45 [LL_DEBUG] = "normal",
46 [LL_INFO] = "normal",
47 [LL_NOTICE] = "normal",
48 [LL_WARNING] = "yellow",
49 [LL_ERROR] = "red",
50 [LL_CRIT] = "magenta bold",
51 [LL_EMERG] = "red bold",
52 };
53 for (i = 0; i < NUM_LOGLEVELS; i++)
54 color_parse_or_die(default_log_colors[i], me->log_colors[i]);
55 }
56
57 /**
58 * Set the color for one loglevel.
59 *
60 * \param arg Must be of the form "ll:[fg [bg]] [attr]".
61 */
62 void daemon_set_log_color_or_die(const char *arg)
63 {
64 char *p = strchr(arg, ':');
65 int ret, ll;
66
67 if (!p)
68 goto err;
69 ret = get_loglevel_by_name(arg);
70 if (ret < 0)
71 goto err;
72 ll = ret;
73 p++;
74 color_parse_or_die(p, me->log_colors[ll]);
75 return;
76 err:
77 PARA_EMERG_LOG("%s: invalid color argument\n", arg);
78 exit(EXIT_FAILURE);
79 }
80
81 /**
82 * Initialize color mode if necessary.
83 *
84 * \param color_arg The argument given to --color.
85 * \param color_arg_auto The value for automatic color detection.
86 * \param color_arg_no The value to disable colored log messages.
87 * \param logfile_given In auto mode colors are disabled if this value is true.
88 *
89 * If color_arg equals color_arg_no, color mode is disabled. That is, calls to
90 * para_log() will not produce colored output. If color_arg equals
91 * color_arg_auto, the function detects automatically whether to activate
92 * colors. Otherwise color mode is enabled.
93 *
94 * If color mode is to be enabled, the default colors are set for each
95 * loglevel. They can be overwritten by calling daemon_set_log_color_or_die().
96 *
97 * \return Whether colors have been enabled by the function.
98 */
99 bool daemon_init_colors_or_die(int color_arg, int color_arg_auto,
100 int color_arg_no, bool logfile_given)
101 {
102 if (color_arg == color_arg_no)
103 return false;
104 if (color_arg == color_arg_auto) {
105 if (logfile_given)
106 return false;
107 if (!isatty(STDERR_FILENO))
108 return false;
109 }
110 daemon_set_flag(DF_COLOR_LOG);
111 daemon_set_default_log_colors();
112 return true;
113 }
114
115 /**
116 * Init or change the name of the log file.
117 *
118 * \param logfile_name The full path of the logfile.
119 */
120 void daemon_set_logfile(const char *logfile_name)
121 {
122 free(me->logfile_name);
123 me->logfile_name = NULL;
124 if (logfile_name)
125 me->logfile_name = para_strdup(logfile_name);
126 }
127
128 /**
129 * Suppress log messages with severity lower than the given loglevel.
130 *
131 * \param loglevel The smallest level that should be logged.
132 */
133 void daemon_set_loglevel(const char *loglevel)
134 {
135 int ret = get_loglevel_by_name(loglevel);
136
137 assert(ret >= 0);
138 me->loglevel = ret;
139 }
140
141 /**
142 * Set one of the daemon config flags.
143 *
144 * \param flag The flag to set.
145 *
146 * \sa \ref daemon_flags.
147 */
148 void daemon_set_flag(unsigned flag)
149 {
150 me->flags |= flag;
151 }
152
153 static bool daemon_test_flag(unsigned flag)
154 {
155 return me->flags & flag;
156 }
157
158 static void dummy_sighandler(__a_unused int s)
159 {
160 }
161
162 /**
163 * Do the usual stuff to become a daemon.
164 *
165 * \param parent_waits Whether the parent process should pause before exit.
166 *
167 * Fork, become session leader, cd to /, and dup fd 0, 1, 2 to /dev/null. If \a
168 * parent_waits is false, the parent process terminates immediately.
169 * Otherwise, it calls pause() to sleep until it receives \p SIGTERM or \p
170 * SIGCHLD and exits successfully thereafter. This behaviour is useful if the
171 * daemon process should not detach from the console until the child process
172 * has completed its setup.
173 *
174 * \sa fork(2), setsid(2), dup(2), pause(2).
175 */
176 void daemonize(bool parent_waits)
177 {
178 pid_t pid;
179 int null;
180
181 PARA_INFO_LOG("subsequent log messages go to %s\n", me->logfile_name?
182 me->logfile_name : "/dev/null");
183 pid = fork();
184 if (pid < 0)
185 goto err;
186 if (pid) {
187 if (parent_waits) {
188 signal(SIGTERM, dummy_sighandler);
189 signal(SIGCHLD, dummy_sighandler);
190 pause();
191 }
192 exit(EXIT_SUCCESS); /* parent exits */
193 }
194 /* become session leader */
195 if (setsid() < 0)
196 goto err;
197 if (chdir("/") < 0)
198 goto err;
199 null = open("/dev/null", O_RDWR);
200 if (null < 0)
201 goto err;
202 if (dup2(null, STDIN_FILENO) < 0)
203 goto err;
204 if (dup2(null, STDOUT_FILENO) < 0)
205 goto err;
206 if (dup2(null, STDERR_FILENO) < 0)
207 goto err;
208 close(null);
209 return;
210 err:
211 PARA_EMERG_LOG("fatal: %s\n", strerror(errno));
212 exit(EXIT_FAILURE);
213 }
214
215 /**
216 * Close the log file of the daemon.
217 */
218 void daemon_close_log(void)
219 {
220 if (!me->logfile)
221 return;
222 PARA_INFO_LOG("closing logfile\n");
223 fclose(me->logfile);
224 me->logfile = NULL;
225 }
226
227 /**
228 * fopen() the logfile in append mode.
229 *
230 * \return Either succeeds or exits.
231 */
232 void daemon_open_log_or_die(void)
233 {
234 daemon_close_log();
235 if (!me->logfile_name)
236 return;
237 me->logfile = fopen(me->logfile_name, "a");
238 if (!me->logfile) {
239 PARA_EMERG_LOG("can not open %s: %s\n", me->logfile_name,
240 strerror(errno));
241 exit(EXIT_FAILURE);
242 }
243 /* equivalent to setlinebuf(), but portable */
244 setvbuf(me->logfile, NULL, _IOLBF, 0);
245 }
246
247 /**
248 * Log the startup message containing the paraslash version.
249 *
250 * \param name The name of the executable.
251 *
252 * First the given \a name is prefixed with the string "para_". Next the git
253 * version is appended. The resulting string is logged with priority "INFO".
254 */
255 void daemon_log_welcome(const char *name)
256 {
257 PARA_INFO_LOG("welcome to para_%s-" PACKAGE_VERSION " \n", name);
258 }
259
260 /**
261 * Renice the calling process.
262 *
263 * \param prio The priority value to set.
264 *
265 * Errors are not considered fatal, but a warning message is logged if the
266 * underlying call to setpriority(2) fails.
267 */
268 void daemon_set_priority(int prio)
269 {
270 if (setpriority(PRIO_PROCESS, 0, prio) < 0)
271 PARA_WARNING_LOG("could not set priority to %d: %s\n", prio,
272 strerror(errno));
273 }
274
275 /**
276 * Give up superuser privileges.
277 *
278 * \param username The user to switch to.
279 * \param groupname The group to switch to.
280 *
281 * This function returns immediately if not invoked with EUID zero. Otherwise,
282 * it tries to obtain the GID of \a groupname and the UID of \a username. On
283 * success, effective and real GID/UID and the saved set-group-ID/set-user-ID
284 * are all set accordingly. On errors, an appropriate message is logged and
285 * exit() is called to terminate the process.
286 *
287 * \sa getpwnam(3), getuid(2), setuid(2), getgrnam(2), setgid(2)
288 */
289 void daemon_drop_privileges_or_die(const char *username, const char *groupname)
290 {
291 struct passwd *p;
292 char *tmp;
293
294 if (geteuid())
295 return;
296 if (groupname) {
297 struct group *g = getgrnam(groupname);
298 if (!g) {
299 PARA_EMERG_LOG("failed to get group %s: %s\n",
300 groupname, strerror(errno));
301 exit(EXIT_FAILURE);
302 }
303 if (setgid(g->gr_gid) < 0) {
304 PARA_EMERG_LOG("failed to set group id %d: %s\n",
305 (int)g->gr_gid, strerror(errno));
306 exit(EXIT_FAILURE);
307 }
308 }
309 if (!username) {
310 PARA_EMERG_LOG("root privileges, but no user option given\n");
311 exit(EXIT_FAILURE);
312 }
313 tmp = para_strdup(username);
314 p = getpwnam(tmp);
315 free(tmp);
316 if (!p) {
317 PARA_EMERG_LOG("%s: no such user\n", username);
318 exit(EXIT_FAILURE);
319 }
320 PARA_INFO_LOG("dropping root privileges\n");
321 if (setuid(p->pw_uid) < 0) {
322 PARA_EMERG_LOG("failed to set effective user ID (%s)",
323 strerror(errno));
324 exit(EXIT_FAILURE);
325 }
326 PARA_DEBUG_LOG("uid: %d, euid: %d\n", (int)getuid(), (int)geteuid());
327 }
328
329 /**
330 * Set the startup time.
331 *
332 * This should be called once on startup. It sets the start time to the
333 * current time. The stored time is used for retrieving the server uptime.
334 *
335 * \sa time(2), \ref daemon_get_uptime(), \ref daemon_get_uptime_str().
336 */
337 void daemon_set_start_time(void)
338 {
339 time(&me->startuptime);
340 }
341
342 /**
343 * Get the uptime.
344 *
345 * \param current_time The current time.
346 *
347 * The \a current_time pointer may be \p NULL. In this case the function
348 * obtains the current time from the system.
349 *
350 * \return This returns the server uptime in seconds, i.e. the difference
351 * between the current time and the value stored previously via \ref
352 * daemon_set_start_time().
353 */
354 time_t daemon_get_uptime(const struct timeval *current_time)
355 {
356 time_t t;
357
358 if (current_time)
359 return current_time->tv_sec - me->startuptime;
360 time(&t);
361 return difftime(t, me->startuptime);
362 }
363
364 /**
365 * Construct a string containing the current uptime.
366 *
367 * \param current_time See a \ref daemon_get_uptime().
368 *
369 * \return A dynamically allocated string of the form "days:hours:minutes".
370 *
371 * \sa server_uptime.
372 */
373 __malloc char *daemon_get_uptime_str(const struct timeval *current_time)
374 {
375 long t = daemon_get_uptime(current_time);
376 return make_message("%li:%02li:%02li", t / 86400,
377 (t / 3600) % 24, (t / 60) % 60);
378 }
379
380 /**
381 * The log function for para_server and para_audiod.
382 *
383 * \param ll The log level.
384 * \param fmt The format string describing the log message.
385 */
386 __printf_2_3 void daemon_log(int ll, const char* fmt,...)
387 {
388 va_list argp;
389 FILE *fp;
390 struct tm *tm;
391 char *color;
392 bool log_time = daemon_test_flag(DF_LOG_TIME), log_timing =
393 daemon_test_flag(DF_LOG_TIMING);
394
395 ll = PARA_MIN(ll, NUM_LOGLEVELS - 1);
396 ll = PARA_MAX(ll, LL_DEBUG);
397 if (ll < me->loglevel)
398 return;
399
400 fp = me->logfile? me->logfile : stderr;
401 color = daemon_test_flag(DF_COLOR_LOG)? me->log_colors[ll] : NULL;
402 if (color)
403 fprintf(fp, "%s", color);
404 if (log_time || log_timing) {
405 struct timeval tv;
406 clock_get_realtime(&tv);
407 if (daemon_test_flag(DF_LOG_TIME)) { /* print date and time */
408 time_t t1 = tv.tv_sec;
409 char str[100];
410 tm = localtime(&t1);
411 strftime(str, sizeof(str), "%b %d %H:%M:%S", tm);
412 fprintf(fp, "%s%s", str, log_timing? ":" : " ");
413 }
414 if (log_timing) /* print milliseconds */
415 fprintf(fp, "%04lu ", (long unsigned)tv.tv_usec / 1000);
416 }
417 if (daemon_test_flag(DF_LOG_HOSTNAME)) {
418 if (!me->hostname)
419 me->hostname = para_hostname();
420 fprintf(fp, "%s ", me->hostname);
421 }
422 if (daemon_test_flag(DF_LOG_LL)) /* log loglevel */
423 fprintf(fp, "(%d) ", ll);
424 if (daemon_test_flag(DF_LOG_PID)) { /* log pid */
425 pid_t mypid = getpid();
426 fprintf(fp, "(%d) ", (int)mypid);
427 }
428 va_start(argp, fmt);
429 vfprintf(fp, fmt, argp);
430 va_end(argp);
431 if (color)
432 fprintf(fp, "%s", COLOR_RESET);
433 }