daemon.c

   1 /*
   2  * Copyright (C) 1997-2011 Andre Noll <maan@systemlinux.org>
   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 <sys/time.h>
  14 #include <stdbool.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 /**
  42  * Activate default log colors.
  43  *
  44  * This should be called early if color support is wanted.
  45  */
  46 void daemon_set_default_log_colors(void)
  47 {
  48         int i;
  49         static const char *default_log_colors[NUM_LOGLEVELS] = {
  50                 [LL_DEBUG] = "normal",
  51                 [LL_INFO] = "normal",
  52                 [LL_NOTICE] = "normal",
  53                 [LL_WARNING] = "yellow",
  54                 [LL_ERROR] = "red",
  55                 [LL_CRIT] = "magenta bold",
  56                 [LL_EMERG] = "red bold",
  57         };
  58         for (i = 0; i < NUM_LOGLEVELS; i++)
  59                 color_parse_or_die(default_log_colors[i], me->log_colors[i]);
  60 }
  61
  62 /**
  63  * Set the color for one loglevel.
  64  *
  65  * \param arg The loglevel/color specifier.
  66  *
  67  * \a arg must be of the form "ll:[fg [bg]] [attr]".
  68  *
  69  * \return 1 On success, -1 on errors.
  70  */
  71 void daemon_set_log_color_or_die(char const *arg)
  72 {
  73         char *p = strchr(arg, ':');
  74         int ret, ll;
  75
  76         if (!p)
  77                 goto err;
  78         ret = get_loglevel_by_name(arg);
  79         if (ret < 0)
  80                 goto err;
  81         ll = ret;
  82         p++;
  83         color_parse_or_die(p, me->log_colors[ll]);
  84         return;
  85 err:
  86         PARA_EMERG_LOG("%s: color syntax error\n", arg);
  87         exit(EXIT_FAILURE);
  88 }
  89
  90 /**
  91  * Init or change the name of the log file.
  92  *
  93  * \param logfile_name The full path of the logfile.
  94  */
  95 void daemon_set_logfile(char *logfile_name)
  96 {
  97         free(me->logfile_name);
  98         me->logfile_name = NULL;
  99         if (logfile_name)
 100                 me->logfile_name = para_strdup(logfile_name);
 101 }
 102
 103 /**
 104  * Suppress log messages with severity lower than the given loglevel.
 105  *
 106  * \param loglevel The smallest level that should be logged.
 107  */
 108 void daemon_set_loglevel(char *loglevel)
 109 {
 110         int ret = get_loglevel_by_name(loglevel);
 111
 112         assert(ret >= 0);
 113         me->loglevel = ret;
 114 }
 115
 116 /**
 117  * Set one of the daemon config flags.
 118  *
 119  * \param flag The flag to set.
 120  *
 121  * \sa \ref daemon_flags.
 122  */
 123 void daemon_set_flag(unsigned flag)
 124 {
 125         me->flags |= flag;
 126 }
 127
 128 /**
 129  * Clear one of the daemon config flags.
 130  *
 131  * \param flag The flag to clear.
 132  *
 133  * \sa \ref daemon_flags.
 134  */
 135 void daemon_clear_flag(unsigned flag)
 136 {
 137         me->flags &= ~flag;
 138 }
 139
 140 static bool daemon_test_flag(unsigned flag)
 141 {
 142         return me->flags & flag;
 143 }
 144
 145 static void dummy_sighandler(__a_unused int s)
 146 {
 147 }
 148
 149 /**
 150  * Do the usual stuff to become a daemon.
 151  *
 152  * \param parent_waits Whether the parent process should pause before exit.
 153  *
 154  * Fork, become session leader, cd to /, and dup fd 0, 1, 2 to /dev/null. If \a
 155  * parent_waits is false, the parent process terminates immediately.
 156  * Otherwise, it calls pause() to sleep until it receives \p SIGTERM or \p
 157  * SIGCHLD and exits successfully thereafter. This behaviour is useful if the
 158  * daemon process should not detach from the console until the child process
 159  * has completed its setup.
 160  *
 161  * \sa fork(2), setsid(2), dup(2), pause(2).
 162  */
 163 void daemonize(bool parent_waits)
 164 {
 165         pid_t pid;
 166         int null;
 167
 168         PARA_INFO_LOG("daemonizing\n");
 169         pid = fork();
 170         if (pid < 0)
 171                 goto err;
 172         if (pid) {
 173                 if (parent_waits) {
 174                         signal(SIGTERM, dummy_sighandler);
 175                         signal(SIGCHLD, dummy_sighandler);
 176                         pause();
 177                 }
 178                 exit(EXIT_SUCCESS); /* parent exits */
 179         }
 180         /* become session leader */
 181         if (setsid() < 0)
 182                 goto err;
 183         if (chdir("/") < 0)
 184                 goto err;
 185         null = open("/dev/null", O_RDONLY);
 186         if (null < 0)
 187                 goto err;
 188         if (dup2(null, STDIN_FILENO) < 0)
 189                 goto err;
 190         if (dup2(null, STDOUT_FILENO) < 0)
 191                 goto err;
 192         if (dup2(null, STDERR_FILENO) < 0)
 193                 goto err;
 194         close(null);
 195         return;
 196 err:
 197         PARA_EMERG_LOG("fatal: %s\n", strerror(errno));
 198         exit(EXIT_FAILURE);
 199 }
 200
 201 /**
 202  * Close the log file of the daemon.
 203  */
 204 void daemon_close_log(void)
 205 {
 206         if (!me->logfile)
 207                 return;
 208         PARA_INFO_LOG("closing logfile\n");
 209         fclose(me->logfile);
 210         me->logfile = NULL;
 211 }
 212
 213 /**
 214  * fopen() the logfile in append mode.
 215  *
 216  * \return Either succeeds or exits.
 217  */
 218 void daemon_open_log_or_die(void)
 219 {
 220         daemon_close_log();
 221         if (!me->logfile_name)
 222                 return;
 223         me->logfile = fopen(me->logfile_name, "a");
 224         if (!me->logfile) {
 225                 PARA_EMERG_LOG("can not open %s: %s\n", me->logfile_name,
 226                         strerror(errno));
 227                 exit(EXIT_FAILURE);
 228         }
 229         setlinebuf(me->logfile);
 230 }
 231
 232 /**
 233  * Log the startup message containing the paraslash version.
 234  */
 235 void log_welcome(const char *whoami)
 236 {
 237         PARA_INFO_LOG("welcome to %s " PACKAGE_VERSION " ("BUILD_DATE")\n",
 238                 whoami);
 239 }
 240
 241 /**
 242  * Give up superuser privileges.
 243  *
 244  * \param username The user to switch to.
 245  * \param groupname The group to switch to.
 246  *
 247  * This function returns immediately if not invoked with EUID zero. Otherwise,
 248  * it tries to obtain the GID of \a groupname and the UID of \a username.  On
 249  * success, effective and real GID/UID and the saved set-group-ID/set-user-ID
 250  * are all set accordingly. On errors, an appropriate message is logged and
 251  * exit() is called to terminate the process.
 252  *
 253  * \sa getpwnam(3), getuid(2), setuid(2), getgrnam(2), setgid(2)
 254  */
 255 void drop_privileges_or_die(const char *username, const char *groupname)
 256 {
 257         struct passwd *p;
 258         char *tmp;
 259
 260         if (geteuid())
 261                 return;
 262         if (groupname) {
 263                 struct group *g = getgrnam(groupname);
 264                 if (!g) {
 265                         PARA_EMERG_LOG("failed to get group %s: %s\n",
 266                                 groupname, strerror(errno));
 267                         exit(EXIT_FAILURE);
 268                 }
 269                 if (setgid(g->gr_gid) < 0) {
 270                         PARA_EMERG_LOG("failed to set group id %d: %s\n",
 271                                 (int)g->gr_gid, strerror(errno));
 272                         exit(EXIT_FAILURE);
 273                 }
 274         }
 275         if (!username) {
 276                 PARA_EMERG_LOG("root privileges, but no user option given\n");
 277                 exit(EXIT_FAILURE);
 278         }
 279         tmp = para_strdup(username);
 280         p = getpwnam(tmp);
 281         free(tmp);
 282         if (!p) {
 283                 PARA_EMERG_LOG("%s: no such user\n", username);
 284                 exit(EXIT_FAILURE);
 285         }
 286         PARA_INFO_LOG("dropping root privileges\n");
 287         if (setuid(p->pw_uid) < 0) {
 288                 PARA_EMERG_LOG("failed to set effective user ID (%s)",
 289                         strerror(errno));
 290                 exit(EXIT_FAILURE);
 291         }
 292         PARA_DEBUG_LOG("uid: %d, euid: %d\n", (int)getuid(), (int)geteuid());
 293 }
 294
 295 /**
 296  * Set the server startup time.
 297  *
 298  * \param startuptime The value to store as the server start time.
 299  *
 300  * This should be called once on startup with \a startuptime either NULL or a
 301  * pointer to a struct timeval which contains the current time. If \a
 302  * startuptime is NULL, the server start time is set to the current time.
 303  *
 304  * \sa time(2), difftime(3) \ref get_server_uptime(), \ref
 305  * get_server_uptime_str().
 306  */
 307 void set_server_start_time(const struct timeval *startuptime)
 308 {
 309         if (startuptime)
 310                 me->startuptime = startuptime->tv_sec;
 311         else
 312                 time(&me->startuptime);
 313 }
 314
 315 /**
 316  * Get the server uptime.
 317  *
 318  * \param current_time The current time.
 319  *
 320  * The \a current_time pointer may be \p NULL. In this case the function
 321  * obtains the current time from the system.
 322  *
 323  * \return This returns the server uptime in seconds, i.e. the difference
 324  * between the current time and the value stored previously via \ref
 325  * set_server_start_time().
 326  */
 327 time_t get_server_uptime(const struct timeval *current_time)
 328 {
 329         time_t t;
 330
 331         if (current_time)
 332                 return current_time->tv_sec - me->startuptime;
 333         time(&t);
 334         return difftime(t, me->startuptime);
 335 }
 336
 337 /**
 338  * Construct a string containing the current uptime.
 339  *
 340  * \param current_time See a \ref get_server_uptime().
 341  *
 342  * \return A dynamically allocated string of the form "days:hours:minutes".
 343  *
 344  * \sa server_uptime.
 345  */
 346 __malloc char *get_server_uptime_str(const struct timeval *current_time)
 347 {
 348         long t = get_server_uptime(current_time);
 349         return make_message("%li:%02li:%02li", t / 86400,
 350                 (t / 3600) % 24, (t / 60) % 60);
 351 }
 352
 353 /**
 354  * The log function for para_server and para_audiod.
 355  *
 356  * \param ll The log level.
 357  * \param fmt The format string describing the log message.
 358  */
 359 __printf_2_3 void para_log(int ll, const char* fmt,...)
 360 {
 361         va_list argp;
 362         FILE *fp;
 363         struct tm *tm;
 364         char *color;
 365         bool log_time = daemon_test_flag(DF_LOG_TIME), log_timing =
 366                 daemon_test_flag(DF_LOG_TIMING);
 367
 368         ll = PARA_MIN(ll, NUM_LOGLEVELS - 1);
 369         ll = PARA_MAX(ll, LL_DEBUG);
 370         if (ll < me->loglevel)
 371                 return;
 372
 373         fp = me->logfile? me->logfile : stderr;
 374         color = daemon_test_flag(DF_COLOR_LOG)? me->log_colors[ll] : NULL;
 375         if (color)
 376                 fprintf(fp, "%s", color);
 377         if (log_time || log_timing) {
 378                 struct timeval tv;
 379                 gettimeofday(&tv, NULL);
 380                 if (daemon_test_flag(DF_LOG_TIME)) { /* print date and time */
 381                         time_t t1 = tv.tv_sec;
 382                         char str[100];
 383                         tm = localtime(&t1);
 384                         strftime(str, sizeof(str), "%b %d %H:%M:%S", tm);
 385                         fprintf(fp, "%s%s", str, log_timing? ":" : " ");
 386                 }
 387                 if (log_timing) /* print milliseconds */
 388                         fprintf(fp, "%04lu ", (long unsigned)tv.tv_usec / 1000);
 389         }
 390         if (daemon_test_flag(DF_LOG_HOSTNAME)) {
 391                 if (!me->hostname)
 392                         me->hostname = para_hostname();
 393                 fprintf(fp, "%s ", me->hostname);
 394         }
 395         if (daemon_test_flag(DF_LOG_LL)) /* log loglevel */
 396                 fprintf(fp, "(%d) ", ll);
 397         if (daemon_test_flag(DF_LOG_PID)) { /* log pid */
 398                 pid_t mypid = getpid();
 399                 fprintf(fp, "(%d) ", (int)mypid);
 400         }
 401         va_start(argp, fmt);
 402         vfprintf(fp, fmt, argp);
 403         va_end(argp);
 404         if (color)
 405                 fprintf(fp, "%s", COLOR_RESET);
 406 }