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