daemon.c

   1 /*
   2  * Copyright (C) 1997-2009 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
  14 #include "para.h"
  15 #include "daemon.h"
  16 #include "string.h"
  17 #include "color.h"
  18
  19 /** The internal state of the daemon. */
  20 struct daemon {
  21         /** See \ref daemon_flags. */
  22         unsigned flags;
  23         /** Set by \ref daemon_set_logfile(). */
  24         char *logfile_name;
  25         /** Current loglevel, see \ref daemon_set_loglevel(). */
  26         int loglevel;
  27
  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                 int ret = color_parse(default_log_colors[i], me->log_colors[i]);
  59                 assert(ret >= 0);
  60         }
  61 }
  62
  63 /**
  64  * Set the color for one loglevel.
  65  *
  66  * \param arg The loglevel/color specifier.
  67  *
  68  * \a arg must be of the form "ll:[fg [bg]] [attr]".
  69  *
  70  * \return 1 On success, -1 on errors.
  71  */
  72 int daemon_set_log_color(char const *arg)
  73 {
  74         char *p = strchr(arg, ':');
  75         int ret, ll;
  76
  77         if (!p)
  78                 goto err;
  79         ret = get_loglevel_by_name(arg);
  80         if (ret < 0)
  81                 goto err;
  82         ll = ret;
  83         p++;
  84         ret = color_parse(p, me->log_colors[ll]);
  85         if (ret < 0)
  86                 goto err;
  87         return 1;
  88 err:
  89         PARA_ERROR_LOG("%s: color syntax error\n", arg);
  90         return -1;
  91
  92 }
  93
  94 /**
  95  * Init or change the name of the log file.
  96  *
  97  * \param logfile_name The full path of the logfile.
  98  */
  99 void daemon_set_logfile(char *logfile_name)
 100 {
 101         free(me->logfile_name);
 102         me->logfile_name = NULL;
 103         if (logfile_name)
 104                 me->logfile_name = para_strdup(logfile_name);
 105 }
 106
 107 /**
 108  * Suppress log messages with severity lower than the given loglevel.
 109  *
 110  * \param loglevel The smallest level that should be logged.
 111  */
 112 void daemon_set_loglevel(char *loglevel)
 113 {
 114         int ret = get_loglevel_by_name(loglevel);
 115
 116         assert(ret >= 0);
 117         me->loglevel = ret;
 118 }
 119
 120 /**
 121  * Set one of the daemon config flags.
 122  *
 123  * \param flag The flag to set.
 124  *
 125  * \sa \ref daemon_flags.
 126  */
 127 void daemon_set_flag(unsigned flag)
 128 {
 129         me->flags |= flag;
 130 }
 131
 132 /**
 133  * Clear one of the daemon config flags.
 134  *
 135  * \param flag The flag to clear.
 136  *
 137  * \sa \ref daemon_flags.
 138  */
 139 void daemon_clear_flag(unsigned flag)
 140 {
 141         me->flags &= ~flag;
 142 }
 143
 144 static unsigned daemon_test_flag(unsigned flag)
 145 {
 146         return me->flags & flag;
 147 }
 148
 149 /**
 150  * Do the usual stuff to become a daemon.
 151  *
 152  * Fork, become session leader, dup fd 0, 1, 2 to /dev/null.
 153  *
 154  * \sa fork(2), setsid(2), dup(2).
 155  */
 156 void daemonize(void)
 157 {
 158         pid_t pid;
 159         int null;
 160
 161         PARA_INFO_LOG("daemonizing\n");
 162         pid = fork();
 163         if (pid < 0)
 164                 goto err;
 165         if (pid)
 166                 exit(EXIT_SUCCESS); /* parent exits */
 167         /* become session leader */
 168         if (setsid() < 0)
 169                 goto err;
 170         if (chdir("/") < 0)
 171                 goto err;
 172         null = open("/dev/null", O_RDONLY);
 173         if (null < 0)
 174                 goto err;
 175         if (dup2(null, STDIN_FILENO) < 0)
 176                 goto err;
 177         if (dup2(null, STDOUT_FILENO) < 0)
 178                 goto err;
 179         if (dup2(null, STDERR_FILENO) < 0)
 180                 goto err;
 181         close(null);
 182         return;
 183 err:
 184         PARA_EMERG_LOG("fatal: %s\n", strerror(errno));
 185         exit(EXIT_FAILURE);
 186 }
 187
 188 /**
 189  * Close the log file of the daemon.
 190  */
 191 void daemon_close_log(void)
 192 {
 193         if (!me->logfile)
 194                 return;
 195         PARA_INFO_LOG("closing logfile\n");
 196         fclose(me->logfile);
 197         me->logfile = NULL;
 198 }
 199
 200 /**
 201  * fopen() the logfile in append mode.
 202  *
 203  * \return Either succeeds or exits.
 204  */
 205 void daemon_open_log_or_die(void)
 206 {
 207         daemon_close_log();
 208         if (!me->logfile_name)
 209                 return;
 210         me->logfile = fopen(me->logfile_name, "a");
 211         if (!me->logfile) {
 212                 PARA_EMERG_LOG("can not open %s: %s\n", me->logfile_name,
 213                         strerror(errno));
 214                 exit(EXIT_FAILURE);
 215         }
 216         setlinebuf(me->logfile);
 217 }
 218
 219 /**
 220  * Log the startup message containing the paraslash version.
 221  */
 222 void log_welcome(const char *whoami)
 223 {
 224         PARA_INFO_LOG("welcome to %s " PACKAGE_VERSION " ("BUILD_DATE")\n",
 225                 whoami);
 226 }
 227
 228 /**
 229  * Give up superuser privileges.
 230  *
 231  * \param username The user to switch to.
 232  * \param groupname The group to switch to.
 233  *
 234  * This function returns immediately if not invoked with EUID zero. Otherwise,
 235  * it tries to obtain the GID of \a groupname and the UID of \a username.  On
 236  * success, effective and real GID/UID and the saved set-group-ID/set-user-ID
 237  * are all set accordingly. On errors, an appropriate message is logged and
 238  * exit() is called to terminate the process.
 239  *
 240  * \sa getpwnam(3), getuid(2), setuid(2), getgrnam(2), setgid(2)
 241  */
 242 void drop_privileges_or_die(const char *username, const char *groupname)
 243 {
 244         struct passwd *p;
 245         char *tmp;
 246
 247         if (geteuid())
 248                 return;
 249         if (groupname) {
 250                 struct group *g = getgrnam(groupname);
 251                 if (!g) {
 252                         PARA_EMERG_LOG("failed to get group %s: %s\n",
 253                                 groupname, strerror(errno));
 254                         exit(EXIT_FAILURE);
 255                 }
 256                 if (setgid(g->gr_gid) < 0) {
 257                         PARA_EMERG_LOG("failed to set group id %d: %s\n",
 258                                 (int)g->gr_gid, strerror(errno));
 259                         exit(EXIT_FAILURE);
 260                 }
 261         }
 262         if (!username) {
 263                 PARA_EMERG_LOG("root privileges, but no user option given\n");
 264                 exit(EXIT_FAILURE);
 265         }
 266         tmp = para_strdup(username);
 267         p = getpwnam(tmp);
 268         free(tmp);
 269         if (!p) {
 270                 PARA_EMERG_LOG("%s: no such user\n", username);
 271                 exit(EXIT_FAILURE);
 272         }
 273         PARA_INFO_LOG("dropping root privileges\n");
 274         if (setuid(p->pw_uid) < 0) {
 275                 PARA_EMERG_LOG("failed to set effective user ID (%s)",
 276                         strerror(errno));
 277                 exit(EXIT_FAILURE);
 278         }
 279         PARA_DEBUG_LOG("uid: %d, euid: %d\n", (int)getuid(), (int)geteuid());
 280 }
 281
 282 /**
 283  * Set/get the server uptime.
 284  *
 285  * \param set_or_get Chose one of the two modes.
 286  *
 287  * This should be called at startup time with \a set_or_get equal to \p
 288  * UPTIME_SET which sets the uptime to zero.  Subsequent calls with \a
 289  * set_or_get equal to \p UPTIME_GET return the uptime.
 290
 291  * \return Zero if called with \a set_or_get equal to \p UPTIME_SET, the number
 292  * of seconds elapsed since the last reset otherwise.
 293  *
 294  * \sa time(2), difftime(3).
 295  */
 296 time_t server_uptime(enum uptime set_or_get)
 297 {
 298         time_t now;
 299         double diff;
 300
 301         if (set_or_get == UPTIME_SET) {
 302                 time(&me->startuptime);
 303                 return 0;
 304         }
 305         time(&now);
 306         diff = difftime(now, me->startuptime);
 307         return (time_t) diff;
 308 }
 309
 310 /**
 311  * Construct string containing uptime.
 312  *
 313  * \return A dynamically allocated string of the form "days:hours:minutes".
 314  *
 315  * \sa server_uptime.
 316  */
 317 __malloc char *uptime_str(void)
 318 {
 319         long t = server_uptime(UPTIME_GET);
 320         return make_message("%li:%02li:%02li", t / 86400,
 321                 (t / 3600) % 24, (t / 60) % 60);
 322 }
 323
 324 /**
 325  * The log function for para_server and para_audiod.
 326  *
 327  * \param ll The log level.
 328  * \param fmt The format string describing the log message.
 329  */
 330 __printf_2_3 void para_log(int ll, const char* fmt,...)
 331 {
 332         va_list argp;
 333         FILE *fp;
 334         struct tm *tm;
 335         time_t t1;
 336         char *color;
 337
 338         ll = PARA_MIN(ll, NUM_LOGLEVELS - 1);
 339         ll = PARA_MAX(ll, LL_DEBUG);
 340         if (ll < me->loglevel)
 341                 return;
 342
 343         fp = me->logfile? me->logfile : stderr;
 344         color = daemon_test_flag(DF_COLOR_LOG)? me->log_colors[ll] : NULL;
 345         if (color)
 346                 fprintf(fp, "%s", color);
 347         if (daemon_test_flag(DF_LOG_TIME)) { /* print date and time */
 348                 char str[100];
 349                 time(&t1);
 350                 tm = localtime(&t1);
 351                 strftime(str, sizeof(str), "%b %d %H:%M:%S", tm);
 352                 fprintf(fp, "%s ", str);
 353         }
 354         if (daemon_test_flag(DF_LOG_HOSTNAME)) {
 355                 if (!me->hostname)
 356                         me->hostname = para_hostname();
 357                 fprintf(fp, "%s ", me->hostname);
 358         }
 359         if (daemon_test_flag(DF_LOG_LL)) /* log loglevel */
 360                 fprintf(fp, "(%d) ", ll);
 361         if (daemon_test_flag(DF_LOG_PID)) { /* log pid */
 362                 pid_t mypid = getpid();
 363                 fprintf(fp, "(%d) ", (int)mypid);
 364         }
 365         va_start(argp, fmt);
 366         vfprintf(fp, fmt, argp);
 367         va_end(argp);
 368         if (color)
 369                 fprintf(fp, "%s", COLOR_RESET);
 370 }