Improve daemon_open_log_or_die().
[paraslash.git] / daemon.c
1 /* Copyright (C) 1997 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
2
3 /** \file daemon.c Some helpers for programs that detach from the console. */
4
5 #include <regex.h>
6 #include <pwd.h>
7 #include <sys/types.h> /* getgrnam() */
8 #include <grp.h>
9 #include <signal.h>
10 #include <sys/resource.h>
11
12 #include "para.h"
13 #include "daemon.h"
14 #include "string.h"
15 #include "color.h"
16
17 /** The internal state of the daemon. */
18 struct daemon {
19 /** See \ref daemon_flags. */
20 unsigned flags;
21 /** Set by \ref daemon_set_logfile(). */
22 char *logfile_name;
23 /** Current loglevel, see \ref daemon_set_loglevel(). */
24 int loglevel;
25 /** Used by \ref server_uptime() and \ref uptime_str(). */
26 time_t startuptime;
27 /** The file pointer if the logfile is open. */
28 FILE *logfile;
29 /** Used by para_log() if \p DF_LOG_HOSTNAME is set. */
30 char *hostname;
31 /** Used for colored log messages. */
32 char log_colors[NUM_LOGLEVELS][COLOR_MAXLEN];
33 };
34
35 static struct daemon the_daemon, *me = &the_daemon;
36
37 static void daemon_set_default_log_colors(void)
38 {
39 int i;
40 static const char *default_log_colors[NUM_LOGLEVELS] = {
41 [LL_DEBUG] = "normal",
42 [LL_INFO] = "normal",
43 [LL_NOTICE] = "normal",
44 [LL_WARNING] = "yellow",
45 [LL_ERROR] = "red",
46 [LL_CRIT] = "magenta bold",
47 [LL_EMERG] = "red bold",
48 };
49 for (i = 0; i < NUM_LOGLEVELS; i++)
50 color_parse_or_die(default_log_colors[i], me->log_colors[i]);
51 }
52
53 /**
54 * Set the color for one loglevel.
55 *
56 * \param arg Must be of the form "ll:[fg [bg]] [attr]".
57 */
58 void daemon_set_log_color_or_die(const char *arg)
59 {
60 char *p = strchr(arg, ':');
61 int ret, ll;
62
63 if (!p)
64 goto err;
65 ret = get_loglevel_by_name(arg);
66 if (ret < 0)
67 goto err;
68 ll = ret;
69 p++;
70 color_parse_or_die(p, me->log_colors[ll]);
71 return;
72 err:
73 PARA_EMERG_LOG("%s: invalid color argument\n", arg);
74 exit(EXIT_FAILURE);
75 }
76
77 /**
78 * Initialize color mode if necessary.
79 *
80 * \param color_arg The argument given to --color.
81 * \param color_arg_auto The value for automatic color detection.
82 * \param color_arg_no The value to disable colored log messages.
83 * \param logfile_given In auto mode colors are disabled if this value is true.
84 *
85 * If color_arg equals color_arg_no, color mode is disabled. That is, calls to
86 * para_log() will not produce colored output. If color_arg equals
87 * color_arg_auto, the function detects automatically whether to activate
88 * colors. Otherwise color mode is enabled.
89 *
90 * If color mode is to be enabled, the default colors are set for each
91 * loglevel. They can be overwritten by calling daemon_set_log_color_or_die().
92 *
93 * \return Whether colors have been enabled by the function.
94 */
95 bool daemon_init_colors_or_die(int color_arg, int color_arg_auto,
96 int color_arg_no, bool logfile_given)
97 {
98 if (color_arg == color_arg_no)
99 return false;
100 if (color_arg == color_arg_auto) {
101 if (logfile_given)
102 return false;
103 if (!isatty(STDERR_FILENO))
104 return false;
105 }
106 daemon_set_flag(DF_COLOR_LOG);
107 daemon_set_default_log_colors();
108 return true;
109 }
110
111 /**
112 * Init or change the name of the log file.
113 *
114 * \param logfile_name The full path of the logfile.
115 */
116 void daemon_set_logfile(const char *logfile_name)
117 {
118 free(me->logfile_name);
119 me->logfile_name = NULL;
120 if (logfile_name)
121 me->logfile_name = para_strdup(logfile_name);
122 }
123
124 /**
125 * Suppress log messages with severity lower than the given loglevel.
126 *
127 * \param loglevel The smallest level that should be logged.
128 */
129 void daemon_set_loglevel(const char *loglevel)
130 {
131 int ret = get_loglevel_by_name(loglevel);
132
133 assert(ret >= 0);
134 me->loglevel = ret;
135 }
136
137 /**
138 * Set one of the daemon config flags.
139 *
140 * \param flag The flag to set.
141 *
142 * \sa \ref daemon_flags.
143 */
144 void daemon_set_flag(unsigned flag)
145 {
146 me->flags |= flag;
147 }
148
149 static bool daemon_test_flag(unsigned flag)
150 {
151 return me->flags & flag;
152 }
153
154 /**
155 * Do the usual stuff to become a daemon.
156 *
157 * \param parent_waits Whether the parent process should pause before exit.
158 *
159 * Fork, become session leader, cd to /, and dup fd 0, 1, 2 to /dev/null. If \a
160 * parent_waits is false, the parent process terminates immediately.
161 * Otherwise, a pipe is created prior to the fork() and the parent tries to
162 * read a single byte from the reading end of the pipe. The child is supposed
163 * to write to the writing end of the pipe after it completed its setup
164 * procedure successfully. This behaviour is useful to let the parent process
165 * die with an error if the child process aborts early, since in this case the
166 * read() will return non-positive.
167 *
168 * \return This function either succeeds or calls exit(3). If parent_waits is
169 * true, the return value is the file descriptor of the writing end of the
170 * pipe. Otherwise the function returns zero.
171 *
172 * \sa fork(2), setsid(2), dup(2), pause(2).
173 */
174 int daemonize(bool parent_waits)
175 {
176 pid_t pid;
177 int null, pipe_fd[2];
178
179 if (parent_waits && pipe(pipe_fd) < 0)
180 goto err;
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) { /* parent exits */
187 if (parent_waits) {
188 char c;
189 close(pipe_fd[1]);
190 exit(read(pipe_fd[0], &c, 1) <= 0?
191 EXIT_FAILURE : EXIT_SUCCESS);
192 }
193 exit(EXIT_SUCCESS);
194 }
195 if (parent_waits)
196 close(pipe_fd[0]);
197 /* become session leader */
198 if (setsid() < 0)
199 goto err;
200 if (chdir("/") < 0)
201 goto err;
202 null = open("/dev/null", O_RDWR);
203 if (null < 0)
204 goto err;
205 if (dup2(null, STDIN_FILENO) < 0)
206 goto err;
207 if (dup2(null, STDOUT_FILENO) < 0)
208 goto err;
209 if (dup2(null, STDERR_FILENO) < 0)
210 goto err;
211 close(null);
212 return parent_waits? pipe_fd[1] : 0;
213 err:
214 PARA_EMERG_LOG("fatal: %s\n", strerror(errno));
215 exit(EXIT_FAILURE);
216 }
217
218 /**
219 * Close the log file of the daemon.
220 */
221 void daemon_close_log(void)
222 {
223 if (!me->logfile)
224 return;
225 PARA_INFO_LOG("closing logfile\n");
226 fclose(me->logfile);
227 me->logfile = NULL;
228 }
229
230 /**
231 * fopen() the logfile in append mode.
232 *
233 * \return Either succeeds or exits.
234 */
235 void daemon_open_log_or_die(void)
236 {
237 FILE *new_log;
238
239 if (!me->logfile_name)
240 return;
241 new_log = fopen(me->logfile_name, "a");
242 if (!new_log) {
243 PARA_EMERG_LOG("can not open %s: %s\n", me->logfile_name,
244 strerror(errno));
245 exit(EXIT_FAILURE);
246 }
247 daemon_close_log();
248 me->logfile = new_log;
249 /* equivalent to setlinebuf(), but portable */
250 setvbuf(me->logfile, NULL, _IOLBF, 0);
251 }
252
253 /**
254 * Log the startup message containing the paraslash version.
255 *
256 * \param name The name of the executable.
257 *
258 * First the given \a name is prefixed with the string "para_". Next the git
259 * version is appended. The resulting string is logged with priority "INFO".
260 */
261 void daemon_log_welcome(const char *name)
262 {
263 PARA_INFO_LOG("welcome to para_%s-" PACKAGE_VERSION " \n", name);
264 }
265
266 /**
267 * Renice the calling process.
268 *
269 * \param prio The priority value to set.
270 *
271 * Errors are not considered fatal, but a warning message is logged if the
272 * underlying call to setpriority(2) fails.
273 */
274 void daemon_set_priority(int prio)
275 {
276 if (setpriority(PRIO_PROCESS, 0, prio) < 0)
277 PARA_WARNING_LOG("could not set priority to %d: %s\n", prio,
278 strerror(errno));
279 }
280
281 /**
282 * Give up superuser privileges.
283 *
284 * \param username The user to switch to.
285 * \param groupname The group to switch to.
286 *
287 * This function returns immediately if not invoked with EUID zero. Otherwise,
288 * it tries to obtain the GID of \a groupname and the UID of \a username. On
289 * success, effective and real GID/UID and the saved set-group-ID/set-user-ID
290 * are all set accordingly. On errors, an appropriate message is logged and
291 * exit() is called to terminate the process.
292 *
293 * \sa getpwnam(3), getuid(2), setuid(2), getgrnam(2), setgid(2)
294 */
295 void daemon_drop_privileges_or_die(const char *username, const char *groupname)
296 {
297 struct passwd *p;
298 char *tmp;
299
300 if (geteuid())
301 return;
302 if (groupname) {
303 struct group *g = getgrnam(groupname);
304 if (!g) {
305 PARA_EMERG_LOG("failed to get group %s: %s\n",
306 groupname, strerror(errno));
307 exit(EXIT_FAILURE);
308 }
309 if (setgid(g->gr_gid) < 0) {
310 PARA_EMERG_LOG("failed to set group id %d: %s\n",
311 (int)g->gr_gid, strerror(errno));
312 exit(EXIT_FAILURE);
313 }
314 }
315 if (!username) {
316 PARA_EMERG_LOG("root privileges, but no user option given\n");
317 exit(EXIT_FAILURE);
318 }
319 tmp = para_strdup(username);
320 p = getpwnam(tmp);
321 free(tmp);
322 if (!p) {
323 PARA_EMERG_LOG("%s: no such user\n", username);
324 exit(EXIT_FAILURE);
325 }
326 PARA_INFO_LOG("dropping root privileges\n");
327 if (setuid(p->pw_uid) < 0) {
328 PARA_EMERG_LOG("failed to set effective user ID (%s)",
329 strerror(errno));
330 exit(EXIT_FAILURE);
331 }
332 PARA_DEBUG_LOG("uid: %d, euid: %d\n", (int)getuid(), (int)geteuid());
333 }
334
335 /**
336 * Set the startup time.
337 *
338 * This should be called once on startup. It sets the start time to the
339 * current time. The stored time is used for retrieving the server uptime.
340 *
341 * \sa time(2), \ref daemon_get_uptime(), \ref daemon_get_uptime_str().
342 */
343 void daemon_set_start_time(void)
344 {
345 time(&me->startuptime);
346 }
347
348 /**
349 * Get the uptime.
350 *
351 * \param current_time The current time.
352 *
353 * The \a current_time pointer may be \p NULL. In this case the function
354 * obtains the current time from the system.
355 *
356 * \return This returns the server uptime in seconds, i.e. the difference
357 * between the current time and the value stored previously via \ref
358 * daemon_set_start_time().
359 */
360 time_t daemon_get_uptime(const struct timeval *current_time)
361 {
362 time_t t;
363
364 if (current_time)
365 return current_time->tv_sec - me->startuptime;
366 time(&t);
367 return difftime(t, me->startuptime);
368 }
369
370 /**
371 * Construct a string containing the current uptime.
372 *
373 * \param current_time See a \ref daemon_get_uptime().
374 *
375 * \return A dynamically allocated string of the form "days:hours:minutes".
376 */
377 __malloc char *daemon_get_uptime_str(const struct timeval *current_time)
378 {
379 long t = daemon_get_uptime(current_time);
380 return make_message("%li:%02li:%02li", t / 86400,
381 (t / 3600) % 24, (t / 60) % 60);
382 }
383
384 /**
385 * The log function for para_server and para_audiod.
386 *
387 * \param ll The log level.
388 * \param fmt The format string describing the log message.
389 */
390 __printf_2_3 void daemon_log(int ll, const char* fmt,...)
391 {
392 va_list argp;
393 FILE *fp;
394 struct tm *tm;
395 char *color;
396 bool log_time = daemon_test_flag(DF_LOG_TIME), log_timing =
397 daemon_test_flag(DF_LOG_TIMING);
398
399 ll = PARA_MIN(ll, NUM_LOGLEVELS - 1);
400 ll = PARA_MAX(ll, LL_DEBUG);
401 if (ll < me->loglevel)
402 return;
403
404 fp = me->logfile? me->logfile : stderr;
405 color = daemon_test_flag(DF_COLOR_LOG)? me->log_colors[ll] : NULL;
406 if (color)
407 fprintf(fp, "%s", color);
408 if (log_time || log_timing) {
409 struct timeval tv;
410 clock_get_realtime(&tv);
411 if (daemon_test_flag(DF_LOG_TIME)) { /* print date and time */
412 time_t t1 = tv.tv_sec;
413 char str[100];
414 tm = localtime(&t1);
415 strftime(str, sizeof(str), "%b %d %H:%M:%S", tm);
416 fprintf(fp, "%s%s", str, log_timing? ":" : " ");
417 }
418 if (log_timing) /* print milliseconds */
419 fprintf(fp, "%04lu ", (long unsigned)tv.tv_usec / 1000);
420 }
421 if (daemon_test_flag(DF_LOG_HOSTNAME)) {
422 if (!me->hostname)
423 me->hostname = para_hostname();
424 fprintf(fp, "%s ", me->hostname);
425 }
426 if (daemon_test_flag(DF_LOG_LL)) /* log loglevel */
427 fprintf(fp, "(%d) ", ll);
428 if (daemon_test_flag(DF_LOG_PID)) { /* log pid */
429 pid_t mypid = getpid();
430 fprintf(fp, "(%d) ", (int)mypid);
431 }
432 va_start(argp, fmt);
433 vfprintf(fp, fmt, argp);
434 va_end(argp);
435 if (color)
436 fprintf(fp, "%s", COLOR_RESET);
437 }