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 #include <signal.h>
  16
  17 #include "para.h"
  18 #include "daemon.h"
  19 #include "string.h"
  20 #include "color.h"
  21
  22 /** The internal state of the daemon. */
  23 struct daemon {
  24         /** See \ref daemon_flags. */
  25         unsigned flags;
  26         /** Set by \ref daemon_set_logfile(). */
  27         char *logfile_name;
  28         /** Current loglevel, see \ref daemon_set_loglevel(). */
  29         int loglevel;
  30         /** Used by \ref server_uptime() and \ref uptime_str(). */
  31         time_t startuptime;
  32         /** The file pointer if the logfile is open. */
  33         FILE *logfile;
  34         /** Used by para_log() if \p DF_LOG_HOSTNAME is set. */
  35         char *hostname;
  36         /** Used for colored log messages. */
  37         char log_colors[NUM_LOGLEVELS][COLOR_MAXLEN];
  38 };
  39
  40 static struct daemon the_daemon, *me = &the_daemon;
  41
  42 /**
  43  * Activate default log colors.
  44  *
  45  * This should be called early if color support is wanted.
  46  */
  47 void daemon_set_default_log_colors(void)
  48 {
  49         int i;
  50         static const char *default_log_colors[NUM_LOGLEVELS] = {
  51                 [LL_DEBUG] = "normal",
  52                 [LL_INFO] = "normal",
  53                 [LL_NOTICE] = "normal",
  54                 [LL_WARNING] = "yellow",
  55                 [LL_ERROR] = "red",
  56                 [LL_CRIT] = "magenta bold",
  57                 [LL_EMERG] = "red bold",
  58         };
  59         for (i = 0; i < NUM_LOGLEVELS; i++)
  60                 color_parse_or_die(default_log_colors[i], me->log_colors[i]);
  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 void daemon_set_log_color_or_die(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         color_parse_or_die(p, me->log_colors[ll]);
  85         return;
  86 err:
  87         PARA_EMERG_LOG("%s: color syntax error\n", arg);
  88         exit(EXIT_FAILURE);
  89 }
  90
  91 /**
  92  * Init or change the name of the log file.
  93  *
  94  * \param logfile_name The full path of the logfile.
  95  */
  96 void daemon_set_logfile(char *logfile_name)
  97 {
  98         free(me->logfile_name);
  99         me->logfile_name = NULL;
 100         if (logfile_name)
 101                 me->logfile_name = para_strdup(logfile_name);
 102 }
 103
 104 /**
 105  * Suppress log messages with severity lower than the given loglevel.
 106  *
 107  * \param loglevel The smallest level that should be logged.
 108  */
 109 void daemon_set_loglevel(char *loglevel)
 110 {
 111         int ret = get_loglevel_by_name(loglevel);
 112
 113         assert(ret >= 0);
 114         me->loglevel = ret;
 115 }
 116
 117 /**
 118  * Set one of the daemon config flags.
 119  *
 120  * \param flag The flag to set.
 121  *
 122  * \sa \ref daemon_flags.
 123  */
 124 void daemon_set_flag(unsigned flag)
 125 {
 126         me->flags |= flag;
 127 }
 128
 129 /**
 130  * Clear one of the daemon config flags.
 131  *
 132  * \param flag The flag to clear.
 133  *
 134  * \sa \ref daemon_flags.
 135  */
 136 void daemon_clear_flag(unsigned flag)
 137 {
 138         me->flags &= ~flag;
 139 }
 140
 141 static bool daemon_test_flag(unsigned flag)
 142 {
 143         return me->flags & flag;
 144 }
 145
 146 static void dummy_sighandler(__a_unused int s)
 147 {
 148 }
 149
 150 /**
 151  * Do the usual stuff to become a daemon.
 152  *
 153  * \param parent_waits Whether the parent process should pause before exit.
 154  *
 155  * Fork, become session leader, cd to /, and dup fd 0, 1, 2 to /dev/null. If \a
 156  * parent_waits is false, the parent process terminates immediately.
 157  * Otherwise, it calls pause() to sleep until it receives \p SIGTERM or \p
 158  * SIGCHLD and exits successfully thereafter. This behaviour is useful if the
 159  * daemon process should not detach from the console until the child process
 160  * has completed its setup.
 161  *
 162  * \sa fork(2), setsid(2), dup(2), pause(2).
 163  */
 164 void daemonize(bool parent_waits)
 165 {
 166         pid_t pid;
 167         int null;
 168
 169         PARA_INFO_LOG("daemonizing\n");
 170         pid = fork();
 171         if (pid < 0)
 172                 goto err;
 173         if (pid) {
 174                 if (parent_waits) {
 175                         signal(SIGTERM, dummy_sighandler);
 176                         signal(SIGCHLD, dummy_sighandler);
 177                         pause();
 178                 }
 179                 exit(EXIT_SUCCESS); /* parent exits */
 180         }
 181         /* become session leader */
 182         if (setsid() < 0)
 183                 goto err;
 184         if (chdir("/") < 0)
 185                 goto err;
 186         null = open("/dev/null", O_RDONLY);
 187         if (null < 0)
 188                 goto err;
 189         if (dup2(null, STDIN_FILENO) < 0)
 190                 goto err;
 191         if (dup2(null, STDOUT_FILENO) < 0)
 192                 goto err;
 193         if (dup2(null, STDERR_FILENO) < 0)
 194                 goto err;
 195         close(null);
 196         return;
 197 err:
 198         PARA_EMERG_LOG("fatal: %s\n", strerror(errno));
 199         exit(EXIT_FAILURE);
 200 }
 201
 202 /**
 203  * Close the log file of the daemon.
 204  */
 205 void daemon_close_log(void)
 206 {
 207         if (!me->logfile)
 208                 return;
 209         PARA_INFO_LOG("closing logfile\n");
 210         fclose(me->logfile);
 211         me->logfile = NULL;
 212 }
 213
 214 /**
 215  * fopen() the logfile in append mode.
 216  *
 217  * \return Either succeeds or exits.
 218  */
 219 void daemon_open_log_or_die(void)
 220 {
 221         daemon_close_log();
 222         if (!me->logfile_name)
 223                 return;
 224         me->logfile = fopen(me->logfile_name, "a");
 225         if (!me->logfile) {
 226                 PARA_EMERG_LOG("can not open %s: %s\n", me->logfile_name,
 227                         strerror(errno));
 228                 exit(EXIT_FAILURE);
 229         }
 230         setlinebuf(me->logfile);
 231 }
 232
 233 /**
 234  * Log the startup message containing the paraslash version.
 235  */
 236 void log_welcome(const char *whoami)
 237 {
 238         PARA_INFO_LOG("welcome to %s " PACKAGE_VERSION " ("BUILD_DATE")\n",
 239                 whoami);
 240 }
 241
 242 /**
 243  * Give up superuser privileges.
 244  *
 245  * \param username The user to switch to.
 246  * \param groupname The group to switch to.
 247  *
 248  * This function returns immediately if not invoked with EUID zero. Otherwise,
 249  * it tries to obtain the GID of \a groupname and the UID of \a username.  On
 250  * success, effective and real GID/UID and the saved set-group-ID/set-user-ID
 251  * are all set accordingly. On errors, an appropriate message is logged and
 252  * exit() is called to terminate the process.
 253  *
 254  * \sa getpwnam(3), getuid(2), setuid(2), getgrnam(2), setgid(2)
 255  */
 256 void drop_privileges_or_die(const char *username, const char *groupname)
 257 {
 258         struct passwd *p;
 259         char *tmp;
 260
 261         if (geteuid())
 262                 return;
 263         if (groupname) {
 264                 struct group *g = getgrnam(groupname);
 265                 if (!g) {
 266                         PARA_EMERG_LOG("failed to get group %s: %s\n",
 267                                 groupname, strerror(errno));
 268                         exit(EXIT_FAILURE);
 269                 }
 270                 if (setgid(g->gr_gid) < 0) {
 271                         PARA_EMERG_LOG("failed to set group id %d: %s\n",
 272                                 (int)g->gr_gid, strerror(errno));
 273                         exit(EXIT_FAILURE);
 274                 }
 275         }
 276         if (!username) {
 277                 PARA_EMERG_LOG("root privileges, but no user option given\n");
 278                 exit(EXIT_FAILURE);
 279         }
 280         tmp = para_strdup(username);
 281         p = getpwnam(tmp);
 282         free(tmp);
 283         if (!p) {
 284                 PARA_EMERG_LOG("%s: no such user\n", username);
 285                 exit(EXIT_FAILURE);
 286         }
 287         PARA_INFO_LOG("dropping root privileges\n");
 288         if (setuid(p->pw_uid) < 0) {
 289                 PARA_EMERG_LOG("failed to set effective user ID (%s)",
 290                         strerror(errno));
 291                 exit(EXIT_FAILURE);
 292         }
 293         PARA_DEBUG_LOG("uid: %d, euid: %d\n", (int)getuid(), (int)geteuid());
 294 }
 295
 296 /**
 297  * Set the server startup time.
 298  *
 299  * \param startuptime The value to store as the server start time.
 300  *
 301  * This should be called once on startup with \a startuptime either NULL or a
 302  * pointer to a struct timeval which contains the current time. If \a
 303  * startuptime is NULL, the server start time is set to the current time.
 304  *
 305  * \sa time(2), difftime(3) \ref get_server_uptime(), \ref
 306  * get_server_uptime_str().
 307  */
 308 void set_server_start_time(const struct timeval *startuptime)
 309 {
 310         if (startuptime)
 311                 me->startuptime = startuptime->tv_sec;
 312         else
 313                 time(&me->startuptime);
 314 }
 315
 316 /**
 317  * Get the server uptime.
 318  *
 319  * \param current_time The current time.
 320  *
 321  * The \a current_time pointer may be \p NULL. In this case the function
 322  * obtains the current time from the system.
 323  *
 324  * \return This returns the server uptime in seconds, i.e. the difference
 325  * between the current time and the value stored previously via \ref
 326  * set_server_start_time().
 327  */
 328 time_t get_server_uptime(const struct timeval *current_time)
 329 {
 330         time_t t;
 331
 332         if (current_time)
 333                 return current_time->tv_sec - me->startuptime;
 334         time(&t);
 335         return difftime(t, me->startuptime);
 336 }
 337
 338 /**
 339  * Construct a string containing the current uptime.
 340  *
 341  * \param current_time See a \ref get_server_uptime().
 342  *
 343  * \return A dynamically allocated string of the form "days:hours:minutes".
 344  *
 345  * \sa server_uptime.
 346  */
 347 __malloc char *get_server_uptime_str(const struct timeval *current_time)
 348 {
 349         long t = get_server_uptime(current_time);
 350         return make_message("%li:%02li:%02li", t / 86400,
 351                 (t / 3600) % 24, (t / 60) % 60);
 352 }
 353
 354 /**
 355  * The log function for para_server and para_audiod.
 356  *
 357  * \param ll The log level.
 358  * \param fmt The format string describing the log message.
 359  */
 360 __printf_2_3 void para_log(int ll, const char* fmt,...)
 361 {
 362         va_list argp;
 363         FILE *fp;
 364         struct tm *tm;
 365         char *color;
 366         bool log_time = daemon_test_flag(DF_LOG_TIME), log_timing =
 367                 daemon_test_flag(DF_LOG_TIMING);
 368
 369         ll = PARA_MIN(ll, NUM_LOGLEVELS - 1);
 370         ll = PARA_MAX(ll, LL_DEBUG);
 371         if (ll < me->loglevel)
 372                 return;
 373
 374         fp = me->logfile? me->logfile : stderr;
 375         color = daemon_test_flag(DF_COLOR_LOG)? me->log_colors[ll] : NULL;
 376         if (color)
 377                 fprintf(fp, "%s", color);
 378         if (log_time || log_timing) {
 379                 struct timeval tv;
 380                 gettimeofday(&tv, NULL);
 381                 if (daemon_test_flag(DF_LOG_TIME)) { /* print date and time */
 382                         time_t t1 = tv.tv_sec;
 383                         char str[100];
 384                         tm = localtime(&t1);
 385                         strftime(str, sizeof(str), "%b %d %H:%M:%S", tm);
 386                         fprintf(fp, "%s%s", str, log_timing? ":" : " ");
 387                 }
 388                 if (log_timing) /* print milliseconds */
 389                         fprintf(fp, "%04lu ", (long unsigned)tv.tv_usec / 1000);
 390         }
 391         if (daemon_test_flag(DF_LOG_HOSTNAME)) {
 392                 if (!me->hostname)
 393                         me->hostname = para_hostname();
 394                 fprintf(fp, "%s ", me->hostname);
 395         }
 396         if (daemon_test_flag(DF_LOG_LL)) /* log loglevel */
 397                 fprintf(fp, "(%d) ", ll);
 398         if (daemon_test_flag(DF_LOG_PID)) { /* log pid */
 399                 pid_t mypid = getpid();
 400                 fprintf(fp, "(%d) ", (int)mypid);
 401         }
 402         va_start(argp, fmt);
 403         vfprintf(fp, fmt, argp);
 404         va_end(argp);
 405         if (color)
 406                 fprintf(fp, "%s", COLOR_RESET);
 407 }