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 static void daemon_set_default_log_colors(void)
  41 {
  42         int i;
  43         static const char *default_log_colors[NUM_LOGLEVELS] = {
  44                 [LL_DEBUG] = "normal",
  45                 [LL_INFO] = "normal",
  46                 [LL_NOTICE] = "normal",
  47                 [LL_WARNING] = "yellow",
  48                 [LL_ERROR] = "red",
  49                 [LL_CRIT] = "magenta bold",
  50                 [LL_EMERG] = "red bold",
  51         };
  52         for (i = 0; i < NUM_LOGLEVELS; i++)
  53                 color_parse_or_die(default_log_colors[i], me->log_colors[i]);
  54 }
  55
  56 /*
  57  * Set the color for one loglevel.
  58  *
  59  * arg must be of the form "ll:[fg [bg]] [attr]".
  60  */
  61 static void daemon_set_log_color_or_die(char const *arg)
  62 {
  63         char *p = strchr(arg, ':');
  64         int ret, ll;
  65
  66         if (!p)
  67                 goto err;
  68         ret = get_loglevel_by_name(arg);
  69         if (ret < 0)
  70                 goto err;
  71         ll = ret;
  72         p++;
  73         color_parse_or_die(p, me->log_colors[ll]);
  74         return;
  75 err:
  76         PARA_EMERG_LOG("%s: color syntax error\n", arg);
  77         exit(EXIT_FAILURE);
  78 }
  79
  80 /**
  81  * Initialize color mode if necessary.
  82  *
  83  * \param color_arg The argument given to --color.
  84  * \param color_arg_auto The value for automatic color detection.
  85  * \param color_arg_no The value to disable colored log messages.
  86  * \param logfile_given In auto mode colors are disabled if this value is true.
  87  * \param log_color_argv Color specifiers given to --log-color.
  88  * \param argc Number of color specifiers in \a log_color_argv.
  89  *
  90  * If \a color_arg equals \a color_arg_no, color mode is disabled, i.e., calls
  91  * to \a para_log() will not produce colored output. If \a color_arg == \a
  92  * color_arg_auto, the function autodetects whether to activate colors.
  93  * Otherwise color mode is enabled.
  94  *
  95  * If color mode is to be enabled, the strings in \a log_color_argv are parsed
  96  * and the color scheme is updated accordingly. For each loglevel, the default
  97  * colors apply if there is no log_color_argv for this loglevel.
  98  */
  99 void daemon_init_colors_or_die(int color_arg, int color_arg_auto,
 100                 int color_arg_no, bool logfile_given, char **log_color_argv,
 101                 int argc)
 102 {
 103         int i;
 104
 105         if (color_arg == color_arg_no)
 106                 return;
 107         if (color_arg == color_arg_auto) {
 108                 if (logfile_given)
 109                         return;
 110                 if (!isatty(STDERR_FILENO))
 111                         return;
 112         }
 113         daemon_set_flag(DF_COLOR_LOG);
 114         daemon_set_default_log_colors();
 115         for (i = 0; i < argc; i++)
 116                 daemon_set_log_color_or_die(log_color_argv[i]);
 117 }
 118
 119 /**
 120  * Init or change the name of the log file.
 121  *
 122  * \param logfile_name The full path of the logfile.
 123  */
 124 void daemon_set_logfile(char *logfile_name)
 125 {
 126         free(me->logfile_name);
 127         me->logfile_name = NULL;
 128         if (logfile_name)
 129                 me->logfile_name = para_strdup(logfile_name);
 130 }
 131
 132 /**
 133  * Suppress log messages with severity lower than the given loglevel.
 134  *
 135  * \param loglevel The smallest level that should be logged.
 136  */
 137 void daemon_set_loglevel(char *loglevel)
 138 {
 139         int ret = get_loglevel_by_name(loglevel);
 140
 141         assert(ret >= 0);
 142         me->loglevel = ret;
 143 }
 144
 145 /**
 146  * Set one of the daemon config flags.
 147  *
 148  * \param flag The flag to set.
 149  *
 150  * \sa \ref daemon_flags.
 151  */
 152 void daemon_set_flag(unsigned flag)
 153 {
 154         me->flags |= flag;
 155 }
 156
 157 static bool daemon_test_flag(unsigned flag)
 158 {
 159         return me->flags & flag;
 160 }
 161
 162 static void dummy_sighandler(__a_unused int s)
 163 {
 164 }
 165
 166 /**
 167  * Do the usual stuff to become a daemon.
 168  *
 169  * \param parent_waits Whether the parent process should pause before exit.
 170  *
 171  * Fork, become session leader, cd to /, and dup fd 0, 1, 2 to /dev/null. If \a
 172  * parent_waits is false, the parent process terminates immediately.
 173  * Otherwise, it calls pause() to sleep until it receives \p SIGTERM or \p
 174  * SIGCHLD and exits successfully thereafter. This behaviour is useful if the
 175  * daemon process should not detach from the console until the child process
 176  * has completed its setup.
 177  *
 178  * \sa fork(2), setsid(2), dup(2), pause(2).
 179  */
 180 void daemonize(bool parent_waits)
 181 {
 182         pid_t pid;
 183         int null;
 184
 185         PARA_INFO_LOG("daemonizing\n");
 186         pid = fork();
 187         if (pid < 0)
 188                 goto err;
 189         if (pid) {
 190                 if (parent_waits) {
 191                         signal(SIGTERM, dummy_sighandler);
 192                         signal(SIGCHLD, dummy_sighandler);
 193                         pause();
 194                 }
 195                 exit(EXIT_SUCCESS); /* parent exits */
 196         }
 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;
 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         daemon_close_log();
 238         if (!me->logfile_name)
 239                 return;
 240         me->logfile = fopen(me->logfile_name, "a");
 241         if (!me->logfile) {
 242                 PARA_EMERG_LOG("can not open %s: %s\n", me->logfile_name,
 243                         strerror(errno));
 244                 exit(EXIT_FAILURE);
 245         }
 246         /* equivalent to setlinebuf(), but portable */
 247         setvbuf(me->logfile, NULL, _IOLBF, 0);
 248 }
 249
 250 /**
 251  * Log the startup message containing the paraslash version.
 252  */
 253 void daemon_log_welcome(const char *whoami)
 254 {
 255         PARA_INFO_LOG("welcome to %s " PACKAGE_VERSION " ("BUILD_DATE")\n",
 256                 whoami);
 257 }
 258
 259 /**
 260  * Give up superuser privileges.
 261  *
 262  * \param username The user to switch to.
 263  * \param groupname The group to switch to.
 264  *
 265  * This function returns immediately if not invoked with EUID zero. Otherwise,
 266  * it tries to obtain the GID of \a groupname and the UID of \a username.  On
 267  * success, effective and real GID/UID and the saved set-group-ID/set-user-ID
 268  * are all set accordingly. On errors, an appropriate message is logged and
 269  * exit() is called to terminate the process.
 270  *
 271  * \sa getpwnam(3), getuid(2), setuid(2), getgrnam(2), setgid(2)
 272  */
 273 void daemon_drop_privileges_or_die(const char *username, const char *groupname)
 274 {
 275         struct passwd *p;
 276         char *tmp;
 277
 278         if (geteuid())
 279                 return;
 280         if (groupname) {
 281                 struct group *g = getgrnam(groupname);
 282                 if (!g) {
 283                         PARA_EMERG_LOG("failed to get group %s: %s\n",
 284                                 groupname, strerror(errno));
 285                         exit(EXIT_FAILURE);
 286                 }
 287                 if (setgid(g->gr_gid) < 0) {
 288                         PARA_EMERG_LOG("failed to set group id %d: %s\n",
 289                                 (int)g->gr_gid, strerror(errno));
 290                         exit(EXIT_FAILURE);
 291                 }
 292         }
 293         if (!username) {
 294                 PARA_EMERG_LOG("root privileges, but no user option given\n");
 295                 exit(EXIT_FAILURE);
 296         }
 297         tmp = para_strdup(username);
 298         p = getpwnam(tmp);
 299         free(tmp);
 300         if (!p) {
 301                 PARA_EMERG_LOG("%s: no such user\n", username);
 302                 exit(EXIT_FAILURE);
 303         }
 304         PARA_INFO_LOG("dropping root privileges\n");
 305         if (setuid(p->pw_uid) < 0) {
 306                 PARA_EMERG_LOG("failed to set effective user ID (%s)",
 307                         strerror(errno));
 308                 exit(EXIT_FAILURE);
 309         }
 310         PARA_DEBUG_LOG("uid: %d, euid: %d\n", (int)getuid(), (int)geteuid());
 311 }
 312
 313 /**
 314  * Set the startup time.
 315  *
 316  * This should be called once on startup. It sets the start time to the
 317  * current time. The stored time is used for retrieving the server uptime.
 318  *
 319  * \sa time(2), \ref daemon_get_uptime(), \ref daemon_get_uptime_str().
 320  */
 321 void daemon_set_start_time(void)
 322 {
 323         time(&me->startuptime);
 324 }
 325
 326 /**
 327  * Get the uptime.
 328  *
 329  * \param current_time The current time.
 330  *
 331  * The \a current_time pointer may be \p NULL. In this case the function
 332  * obtains the current time from the system.
 333  *
 334  * \return This returns the server uptime in seconds, i.e. the difference
 335  * between the current time and the value stored previously via \ref
 336  * daemon_set_start_time().
 337  */
 338 time_t daemon_get_uptime(const struct timeval *current_time)
 339 {
 340         time_t t;
 341
 342         if (current_time)
 343                 return current_time->tv_sec - me->startuptime;
 344         time(&t);
 345         return difftime(t, me->startuptime);
 346 }
 347
 348 /**
 349  * Construct a string containing the current uptime.
 350  *
 351  * \param current_time See a \ref daemon_get_uptime().
 352  *
 353  * \return A dynamically allocated string of the form "days:hours:minutes".
 354  *
 355  * \sa server_uptime.
 356  */
 357 __malloc char *daemon_get_uptime_str(const struct timeval *current_time)
 358 {
 359         long t = daemon_get_uptime(current_time);
 360         return make_message("%li:%02li:%02li", t / 86400,
 361                 (t / 3600) % 24, (t / 60) % 60);
 362 }
 363
 364 /**
 365  * The log function for para_server and para_audiod.
 366  *
 367  * \param ll The log level.
 368  * \param fmt The format string describing the log message.
 369  */
 370 __printf_2_3 void daemon_log(int ll, const char* fmt,...)
 371 {
 372         va_list argp;
 373         FILE *fp;
 374         struct tm *tm;
 375         char *color;
 376         bool log_time = daemon_test_flag(DF_LOG_TIME), log_timing =
 377                 daemon_test_flag(DF_LOG_TIMING);
 378
 379         ll = PARA_MIN(ll, NUM_LOGLEVELS - 1);
 380         ll = PARA_MAX(ll, LL_DEBUG);
 381         if (ll < me->loglevel)
 382                 return;
 383
 384         fp = me->logfile? me->logfile : stderr;
 385         color = daemon_test_flag(DF_COLOR_LOG)? me->log_colors[ll] : NULL;
 386         if (color)
 387                 fprintf(fp, "%s", color);
 388         if (log_time || log_timing) {
 389                 struct timeval tv;
 390                 clock_get_realtime(&tv);
 391                 if (daemon_test_flag(DF_LOG_TIME)) { /* print date and time */
 392                         time_t t1 = tv.tv_sec;
 393                         char str[100];
 394                         tm = localtime(&t1);
 395                         strftime(str, sizeof(str), "%b %d %H:%M:%S", tm);
 396                         fprintf(fp, "%s%s", str, log_timing? ":" : " ");
 397                 }
 398                 if (log_timing) /* print milliseconds */
 399                         fprintf(fp, "%04lu ", (long unsigned)tv.tv_usec / 1000);
 400         }
 401         if (daemon_test_flag(DF_LOG_HOSTNAME)) {
 402                 if (!me->hostname)
 403                         me->hostname = para_hostname();
 404                 fprintf(fp, "%s ", me->hostname);
 405         }
 406         if (daemon_test_flag(DF_LOG_LL)) /* log loglevel */
 407                 fprintf(fp, "(%d) ", ll);
 408         if (daemon_test_flag(DF_LOG_PID)) { /* log pid */
 409                 pid_t mypid = getpid();
 410                 fprintf(fp, "(%d) ", (int)mypid);
 411         }
 412         va_start(argp, fmt);
 413         vfprintf(fp, fmt, argp);
 414         va_end(argp);
 415         if (color)
 416                 fprintf(fp, "%s", COLOR_RESET);
 417 }