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  * arg must be of the form "ll:[fg [bg]] [attr]".
  61  */
  62 static void daemon_set_log_color_or_die(char const *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  * \param log_color_argv Color specifiers given to --log-color.
  89  * \param argc Number of color specifiers in \a log_color_argv.
  90  *
  91  * If \a color_arg equals \a color_arg_no, color mode is disabled, i.e., calls
  92  * to \a para_log() will not produce colored output. If \a color_arg == \a
  93  * color_arg_auto, the function autodetects whether to activate colors.
  94  * Otherwise color mode is enabled.
  95  *
  96  * If color mode is to be enabled, the strings in \a log_color_argv are parsed
  97  * and the color scheme is updated accordingly. For each loglevel, the default
  98  * colors apply if there is no log_color_argv for this loglevel.
  99  */
 100 void daemon_init_colors_or_die(int color_arg, int color_arg_auto,
 101                 int color_arg_no, bool logfile_given, char **log_color_argv,
 102                 int argc)
 103 {
 104         int i;
 105
 106         if (color_arg == color_arg_no)
 107                 return;
 108         if (color_arg == color_arg_auto) {
 109                 if (logfile_given)
 110                         return;
 111                 if (!isatty(STDERR_FILENO))
 112                         return;
 113         }
 114         daemon_set_flag(DF_COLOR_LOG);
 115         daemon_set_default_log_colors();
 116         for (i = 0; i < argc; i++)
 117                 daemon_set_log_color_or_die(log_color_argv[i]);
 118 }
 119
 120 /**
 121  * Init or change the name of the log file.
 122  *
 123  * \param logfile_name The full path of the logfile.
 124  */
 125 void daemon_set_logfile(char *logfile_name)
 126 {
 127         free(me->logfile_name);
 128         me->logfile_name = NULL;
 129         if (logfile_name)
 130                 me->logfile_name = para_strdup(logfile_name);
 131 }
 132
 133 /**
 134  * Suppress log messages with severity lower than the given loglevel.
 135  *
 136  * \param loglevel The smallest level that should be logged.
 137  */
 138 void daemon_set_loglevel(char *loglevel)
 139 {
 140         int ret = get_loglevel_by_name(loglevel);
 141
 142         assert(ret >= 0);
 143         me->loglevel = ret;
 144 }
 145
 146 /**
 147  * Set one of the daemon config flags.
 148  *
 149  * \param flag The flag to set.
 150  *
 151  * \sa \ref daemon_flags.
 152  */
 153 void daemon_set_flag(unsigned flag)
 154 {
 155         me->flags |= flag;
 156 }
 157
 158 static bool daemon_test_flag(unsigned flag)
 159 {
 160         return me->flags & flag;
 161 }
 162
 163 static void dummy_sighandler(__a_unused int s)
 164 {
 165 }
 166
 167 /**
 168  * Do the usual stuff to become a daemon.
 169  *
 170  * \param parent_waits Whether the parent process should pause before exit.
 171  *
 172  * Fork, become session leader, cd to /, and dup fd 0, 1, 2 to /dev/null. If \a
 173  * parent_waits is false, the parent process terminates immediately.
 174  * Otherwise, it calls pause() to sleep until it receives \p SIGTERM or \p
 175  * SIGCHLD and exits successfully thereafter. This behaviour is useful if the
 176  * daemon process should not detach from the console until the child process
 177  * has completed its setup.
 178  *
 179  * \sa fork(2), setsid(2), dup(2), pause(2).
 180  */
 181 void daemonize(bool parent_waits)
 182 {
 183         pid_t pid;
 184         int null;
 185
 186         PARA_INFO_LOG("daemonizing\n");
 187         pid = fork();
 188         if (pid < 0)
 189                 goto err;
 190         if (pid) {
 191                 if (parent_waits) {
 192                         signal(SIGTERM, dummy_sighandler);
 193                         signal(SIGCHLD, dummy_sighandler);
 194                         pause();
 195                 }
 196                 exit(EXIT_SUCCESS); /* parent exits */
 197         }
 198         /* become session leader */
 199         if (setsid() < 0)
 200                 goto err;
 201         if (chdir("/") < 0)
 202                 goto err;
 203         null = open("/dev/null", O_RDWR);
 204         if (null < 0)
 205                 goto err;
 206         if (dup2(null, STDIN_FILENO) < 0)
 207                 goto err;
 208         if (dup2(null, STDOUT_FILENO) < 0)
 209                 goto err;
 210         if (dup2(null, STDERR_FILENO) < 0)
 211                 goto err;
 212         close(null);
 213         return;
 214 err:
 215         PARA_EMERG_LOG("fatal: %s\n", strerror(errno));
 216         exit(EXIT_FAILURE);
 217 }
 218
 219 /**
 220  * Close the log file of the daemon.
 221  */
 222 void daemon_close_log(void)
 223 {
 224         if (!me->logfile)
 225                 return;
 226         PARA_INFO_LOG("closing logfile\n");
 227         fclose(me->logfile);
 228         me->logfile = NULL;
 229 }
 230
 231 /**
 232  * fopen() the logfile in append mode.
 233  *
 234  * \return Either succeeds or exits.
 235  */
 236 void daemon_open_log_or_die(void)
 237 {
 238         daemon_close_log();
 239         if (!me->logfile_name)
 240                 return;
 241         me->logfile = fopen(me->logfile_name, "a");
 242         if (!me->logfile) {
 243                 PARA_EMERG_LOG("can not open %s: %s\n", me->logfile_name,
 244                         strerror(errno));
 245                 exit(EXIT_FAILURE);
 246         }
 247         /* equivalent to setlinebuf(), but portable */
 248         setvbuf(me->logfile, NULL, _IOLBF, 0);
 249 }
 250
 251 /**
 252  * Log the startup message containing the paraslash version.
 253  *
 254  * \param name The name of the executable.
 255  *
 256  * First the given \a name is prefixed with the string "para_". Next the git
 257  * version is appended. The resulting string is logged with priority "INFO".
 258  */
 259 void daemon_log_welcome(const char *name)
 260 {
 261         PARA_INFO_LOG("welcome to para_%s-" PACKAGE_VERSION " \n", name);
 262 }
 263
 264 /**
 265  * Renice the calling process.
 266  *
 267  * \param prio The priority value to set.
 268  *
 269  * Errors are not considered fatal, but a warning message is logged if the
 270  * underlying call to setpriority(2) fails.
 271  */
 272 void daemon_set_priority(int prio)
 273 {
 274         if (setpriority(PRIO_PROCESS, 0, prio) < 0)
 275                 PARA_WARNING_LOG("could not set priority to %d: %s\n", prio,
 276                         strerror(errno));
 277 }
 278
 279 /**
 280  * Give up superuser privileges.
 281  *
 282  * \param username The user to switch to.
 283  * \param groupname The group to switch to.
 284  *
 285  * This function returns immediately if not invoked with EUID zero. Otherwise,
 286  * it tries to obtain the GID of \a groupname and the UID of \a username.  On
 287  * success, effective and real GID/UID and the saved set-group-ID/set-user-ID
 288  * are all set accordingly. On errors, an appropriate message is logged and
 289  * exit() is called to terminate the process.
 290  *
 291  * \sa getpwnam(3), getuid(2), setuid(2), getgrnam(2), setgid(2)
 292  */
 293 void daemon_drop_privileges_or_die(const char *username, const char *groupname)
 294 {
 295         struct passwd *p;
 296         char *tmp;
 297
 298         if (geteuid())
 299                 return;
 300         if (groupname) {
 301                 struct group *g = getgrnam(groupname);
 302                 if (!g) {
 303                         PARA_EMERG_LOG("failed to get group %s: %s\n",
 304                                 groupname, strerror(errno));
 305                         exit(EXIT_FAILURE);
 306                 }
 307                 if (setgid(g->gr_gid) < 0) {
 308                         PARA_EMERG_LOG("failed to set group id %d: %s\n",
 309                                 (int)g->gr_gid, strerror(errno));
 310                         exit(EXIT_FAILURE);
 311                 }
 312         }
 313         if (!username) {
 314                 PARA_EMERG_LOG("root privileges, but no user option given\n");
 315                 exit(EXIT_FAILURE);
 316         }
 317         tmp = para_strdup(username);
 318         p = getpwnam(tmp);
 319         free(tmp);
 320         if (!p) {
 321                 PARA_EMERG_LOG("%s: no such user\n", username);
 322                 exit(EXIT_FAILURE);
 323         }
 324         PARA_INFO_LOG("dropping root privileges\n");
 325         if (setuid(p->pw_uid) < 0) {
 326                 PARA_EMERG_LOG("failed to set effective user ID (%s)",
 327                         strerror(errno));
 328                 exit(EXIT_FAILURE);
 329         }
 330         PARA_DEBUG_LOG("uid: %d, euid: %d\n", (int)getuid(), (int)geteuid());
 331 }
 332
 333 /**
 334  * Set the startup time.
 335  *
 336  * This should be called once on startup. It sets the start time to the
 337  * current time. The stored time is used for retrieving the server uptime.
 338  *
 339  * \sa time(2), \ref daemon_get_uptime(), \ref daemon_get_uptime_str().
 340  */
 341 void daemon_set_start_time(void)
 342 {
 343         time(&me->startuptime);
 344 }
 345
 346 /**
 347  * Get the uptime.
 348  *
 349  * \param current_time The current time.
 350  *
 351  * The \a current_time pointer may be \p NULL. In this case the function
 352  * obtains the current time from the system.
 353  *
 354  * \return This returns the server uptime in seconds, i.e. the difference
 355  * between the current time and the value stored previously via \ref
 356  * daemon_set_start_time().
 357  */
 358 time_t daemon_get_uptime(const struct timeval *current_time)
 359 {
 360         time_t t;
 361
 362         if (current_time)
 363                 return current_time->tv_sec - me->startuptime;
 364         time(&t);
 365         return difftime(t, me->startuptime);
 366 }
 367
 368 /**
 369  * Construct a string containing the current uptime.
 370  *
 371  * \param current_time See a \ref daemon_get_uptime().
 372  *
 373  * \return A dynamically allocated string of the form "days:hours:minutes".
 374  *
 375  * \sa server_uptime.
 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 }