daemon.c

   1 /* Copyright (C) 1997 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
   2
   3 /** \file daemon.c Some helpers for programs that detach from the console. */
   4
   5 #include <regex.h>
   6 #include <pwd.h>
   7 #include <sys/types.h> /* getgrnam() */
   8 #include <grp.h>
   9 #include <signal.h>
  10 #include <sys/resource.h>
  11
  12 #include "para.h"
  13 #include "daemon.h"
  14 #include "string.h"
  15 #include "color.h"
  16
  17 /** The internal state of the daemon. */
  18 struct daemon {
  19         /** See \ref daemon_flags. */
  20         unsigned flags;
  21         /** Set by \ref daemon_set_logfile(). */
  22         char *logfile_name;
  23         /** Current loglevel, see \ref daemon_set_loglevel(). */
  24         int loglevel;
  25         /** Used by \ref server_uptime() and \ref uptime_str(). */
  26         time_t startuptime;
  27         /** The file pointer if the logfile is open. */
  28         FILE *logfile;
  29         /** Used by para_log() if \p DF_LOG_HOSTNAME is set. */
  30         char *hostname;
  31         /** Used for colored log messages. */
  32         char log_colors[NUM_LOGLEVELS][COLOR_MAXLEN];
  33         char *old_cwd;
  34         /*
  35          * If these pointers are non-NULL, the functions are called from
  36          * daemon_log() before and after writing each log message.
  37          */
  38         void (*pre_log_hook)(void);
  39         void (*post_log_hook)(void);
  40 };
  41
  42 static struct daemon the_daemon, *me = &the_daemon;
  43
  44 static void daemon_set_default_log_colors(void)
  45 {
  46         int i;
  47         static const char *default_log_colors[NUM_LOGLEVELS] = {
  48                 [LL_DEBUG] = "normal",
  49                 [LL_INFO] = "normal",
  50                 [LL_NOTICE] = "normal",
  51                 [LL_WARNING] = "yellow",
  52                 [LL_ERROR] = "red",
  53                 [LL_CRIT] = "magenta bold",
  54                 [LL_EMERG] = "red bold",
  55         };
  56         for (i = 0; i < NUM_LOGLEVELS; i++)
  57                 color_parse_or_die(default_log_colors[i], me->log_colors[i]);
  58 }
  59
  60 /**
  61  * Set the color for one loglevel.
  62  *
  63  * \param arg Must be of the form "ll:[fg [bg]] [attr]".
  64  */
  65 void daemon_set_log_color_or_die(const char *arg)
  66 {
  67         char *p = strchr(arg, ':');
  68         int ret, ll;
  69
  70         if (!p)
  71                 goto err;
  72         ret = get_loglevel_by_name(arg);
  73         if (ret < 0)
  74                 goto err;
  75         ll = ret;
  76         p++;
  77         color_parse_or_die(p, me->log_colors[ll]);
  78         return;
  79 err:
  80         PARA_EMERG_LOG("%s: invalid color argument\n", arg);
  81         exit(EXIT_FAILURE);
  82 }
  83
  84 /**
  85  * Initialize color mode if necessary.
  86  *
  87  * \param color_arg The argument given to --color.
  88  * \param color_arg_auto The value for automatic color detection.
  89  * \param color_arg_no The value to disable colored log messages.
  90  * \param logfile_given In auto mode colors are disabled if this value is true.
  91  *
  92  * If color_arg equals color_arg_no, color mode is disabled. That is, calls to
  93  * para_log() will not produce colored output. If color_arg equals
  94  * color_arg_auto, the function detects automatically whether to activate
  95  * colors. Otherwise color mode is enabled.
  96  *
  97  * If color mode is to be enabled, the default colors are set for each
  98  * loglevel. They can be overwritten by calling daemon_set_log_color_or_die().
  99  *
 100  * \return Whether colors have been enabled by the function.
 101  */
 102 bool daemon_init_colors_or_die(int color_arg, int color_arg_auto,
 103                 int color_arg_no, bool logfile_given)
 104 {
 105         if (color_arg == color_arg_no)
 106                 return false;
 107         if (color_arg == color_arg_auto) {
 108                 if (logfile_given)
 109                         return false;
 110                 if (!isatty(STDERR_FILENO))
 111                         return false;
 112         }
 113         daemon_set_flag(DF_COLOR_LOG);
 114         daemon_set_default_log_colors();
 115         return true;
 116 }
 117
 118 /**
 119  * Init or change the name of the log file.
 120  *
 121  * \param logfile_name The full path of the logfile.
 122  */
 123 void daemon_set_logfile(const char *logfile_name)
 124 {
 125         free(me->logfile_name);
 126         me->logfile_name = NULL;
 127         if (!logfile_name)
 128                 return;
 129         if (me->old_cwd && logfile_name[0] != '/')
 130                 me->logfile_name = make_message("%s/%s", me->old_cwd,
 131                         logfile_name);
 132         else
 133                 me->logfile_name = para_strdup(logfile_name);
 134 }
 135
 136 /**
 137  * Suppress log messages with severity lower than the given loglevel.
 138  *
 139  * \param loglevel The smallest level that should be logged.
 140  */
 141 void daemon_set_loglevel(const char *loglevel)
 142 {
 143         int ret = get_loglevel_by_name(loglevel);
 144
 145         assert(ret >= 0);
 146         me->loglevel = ret;
 147 }
 148
 149 void daemon_set_hooks(void (*pre_log_hook)(void), void (*post_log_hook)(void))
 150 {
 151         me->pre_log_hook = pre_log_hook;
 152         me->post_log_hook = post_log_hook;
 153 }
 154
 155 /**
 156  * Set one of the daemon config flags.
 157  *
 158  * \param flag The flag to set.
 159  *
 160  * \sa \ref daemon_flags.
 161  */
 162 void daemon_set_flag(unsigned flag)
 163 {
 164         me->flags |= flag;
 165 }
 166
 167 static bool daemon_test_flag(unsigned flag)
 168 {
 169         return me->flags & flag;
 170 }
 171
 172 /**
 173  * Do the usual stuff to become a daemon.
 174  *
 175  * \param parent_waits Whether the parent process should pause before exit.
 176  *
 177  * Fork, become session leader, cd to /, and dup fd 0, 1, 2 to /dev/null. If \a
 178  * parent_waits is false, the parent process terminates immediately.
 179  * Otherwise, a pipe is created prior to the fork() and the parent tries to
 180  * read a single byte from the reading end of the pipe. The child is supposed
 181  * to write to the writing end of the pipe after it completed its setup
 182  * procedure successfully. This behaviour is useful to let the parent process
 183  * die with an error if the child process aborts early, since in this case the
 184  * read() will return non-positive.
 185  *
 186  * \return This function either succeeds or calls exit(3). If parent_waits is
 187  * true, the return value is the file descriptor of the writing end of the
 188  * pipe. Otherwise the function returns zero.
 189  *
 190  * \sa fork(2), setsid(2), dup(2), pause(2).
 191  */
 192 int daemonize(bool parent_waits)
 193 {
 194         pid_t pid;
 195         int null, pipe_fd[2];
 196
 197         if (parent_waits && pipe(pipe_fd) < 0)
 198                 goto err;
 199         PARA_INFO_LOG("subsequent log messages go to %s\n", me->logfile_name?
 200                  me->logfile_name : "/dev/null");
 201         pid = fork();
 202         if (pid < 0)
 203                 goto err;
 204         if (pid) { /* parent exits */
 205                 if (parent_waits) {
 206                         char c;
 207                         close(pipe_fd[1]);
 208                         exit(read(pipe_fd[0], &c, 1) <= 0?
 209                                 EXIT_FAILURE : EXIT_SUCCESS);
 210                 }
 211                 exit(EXIT_SUCCESS);
 212         }
 213         if (parent_waits)
 214                 close(pipe_fd[0]);
 215         /* become session leader */
 216         if (setsid() < 0)
 217                 goto err;
 218         me->old_cwd = getcwd(NULL, 0);
 219         if (chdir("/") < 0)
 220                 goto err;
 221         null = open("/dev/null", O_RDWR);
 222         if (null < 0)
 223                 goto err;
 224         if (dup2(null, STDIN_FILENO) < 0)
 225                 goto err;
 226         if (dup2(null, STDOUT_FILENO) < 0)
 227                 goto err;
 228         if (dup2(null, STDERR_FILENO) < 0)
 229                 goto err;
 230         close(null);
 231         return parent_waits? pipe_fd[1] : 0;
 232 err:
 233         PARA_EMERG_LOG("fatal: %s\n", strerror(errno));
 234         exit(EXIT_FAILURE);
 235 }
 236
 237 /**
 238  * Close the log file of the daemon.
 239  */
 240 void daemon_close_log(void)
 241 {
 242         if (!me->logfile)
 243                 return;
 244         PARA_INFO_LOG("closing logfile\n");
 245         fclose(me->logfile);
 246         me->logfile = NULL;
 247 }
 248
 249 /**
 250  * fopen() the logfile in append mode.
 251  *
 252  * \return Either succeeds or exits.
 253  */
 254 void daemon_open_log_or_die(void)
 255 {
 256         FILE *new_log;
 257
 258         if (!me->logfile_name)
 259                 return;
 260         new_log = fopen(me->logfile_name, "a");
 261         if (!new_log) {
 262                 PARA_EMERG_LOG("can not open %s: %s\n", me->logfile_name,
 263                         strerror(errno));
 264                 exit(EXIT_FAILURE);
 265         }
 266         daemon_close_log();
 267         me->logfile = new_log;
 268         /* equivalent to setlinebuf(), but portable */
 269         setvbuf(me->logfile, NULL, _IOLBF, 0);
 270 }
 271
 272 /**
 273  * Log the startup message containing the paraslash version.
 274  *
 275  * \param name The name of the executable.
 276  *
 277  * First the given \a name is prefixed with the string "para_". Next the git
 278  * version is appended. The resulting string is logged with priority "INFO".
 279  */
 280 void daemon_log_welcome(const char *name)
 281 {
 282         PARA_INFO_LOG("welcome to para_%s-" PACKAGE_VERSION " \n", name);
 283 }
 284
 285 /**
 286  * Renice the calling process.
 287  *
 288  * \param prio The priority value to set.
 289  *
 290  * Errors are not considered fatal, but a warning message is logged if the
 291  * underlying call to setpriority(2) fails.
 292  */
 293 void daemon_set_priority(int prio)
 294 {
 295         if (setpriority(PRIO_PROCESS, 0, prio) < 0)
 296                 PARA_WARNING_LOG("could not set priority to %d: %s\n", prio,
 297                         strerror(errno));
 298 }
 299
 300 /**
 301  * Give up superuser privileges.
 302  *
 303  * \param username The user to switch to.
 304  * \param groupname The group to switch to.
 305  *
 306  * This function returns immediately if not invoked with EUID zero. Otherwise,
 307  * it tries to obtain the GID of \a groupname and the UID of \a username.  On
 308  * success, effective and real GID/UID and the saved set-group-ID/set-user-ID
 309  * are all set accordingly. On errors, an appropriate message is logged and
 310  * exit() is called to terminate the process.
 311  *
 312  * \sa getpwnam(3), getuid(2), setuid(2), getgrnam(2), setgid(2)
 313  */
 314 void daemon_drop_privileges_or_die(const char *username, const char *groupname)
 315 {
 316         struct passwd *p;
 317         char *tmp;
 318
 319         if (geteuid())
 320                 return;
 321         if (groupname) {
 322                 struct group *g = getgrnam(groupname);
 323                 if (!g) {
 324                         PARA_EMERG_LOG("failed to get group %s: %s\n",
 325                                 groupname, strerror(errno));
 326                         exit(EXIT_FAILURE);
 327                 }
 328                 if (setgid(g->gr_gid) < 0) {
 329                         PARA_EMERG_LOG("failed to set group id %d: %s\n",
 330                                 (int)g->gr_gid, strerror(errno));
 331                         exit(EXIT_FAILURE);
 332                 }
 333         }
 334         if (!username) {
 335                 PARA_EMERG_LOG("root privileges, but no user option given\n");
 336                 exit(EXIT_FAILURE);
 337         }
 338         tmp = para_strdup(username);
 339         p = getpwnam(tmp);
 340         free(tmp);
 341         if (!p) {
 342                 PARA_EMERG_LOG("%s: no such user\n", username);
 343                 exit(EXIT_FAILURE);
 344         }
 345         PARA_INFO_LOG("dropping root privileges\n");
 346         if (setuid(p->pw_uid) < 0) {
 347                 PARA_EMERG_LOG("failed to set effective user ID (%s)",
 348                         strerror(errno));
 349                 exit(EXIT_FAILURE);
 350         }
 351         PARA_DEBUG_LOG("uid: %d, euid: %d\n", (int)getuid(), (int)geteuid());
 352 }
 353
 354 /**
 355  * Set the startup time.
 356  *
 357  * This should be called once on startup. It sets the start time to the
 358  * current time. The stored time is used for retrieving the server uptime.
 359  *
 360  * \sa time(2), \ref daemon_get_uptime(), \ref daemon_get_uptime_str().
 361  */
 362 void daemon_set_start_time(void)
 363 {
 364         time(&me->startuptime);
 365 }
 366
 367 /**
 368  * Get the uptime.
 369  *
 370  * \param current_time The current time.
 371  *
 372  * The \a current_time pointer may be \p NULL. In this case the function
 373  * obtains the current time from the system.
 374  *
 375  * \return This returns the server uptime in seconds, i.e. the difference
 376  * between the current time and the value stored previously via \ref
 377  * daemon_set_start_time().
 378  */
 379 time_t daemon_get_uptime(const struct timeval *current_time)
 380 {
 381         time_t t;
 382
 383         if (current_time)
 384                 return current_time->tv_sec - me->startuptime;
 385         time(&t);
 386         return difftime(t, me->startuptime);
 387 }
 388
 389 /**
 390  * Construct a string containing the current uptime.
 391  *
 392  * \param current_time See a \ref daemon_get_uptime().
 393  *
 394  * \return A dynamically allocated string of the form "days:hours:minutes".
 395  */
 396 __malloc char *daemon_get_uptime_str(const struct timeval *current_time)
 397 {
 398         long t = daemon_get_uptime(current_time);
 399         return make_message("%li:%02li:%02li", t / 86400,
 400                 (t / 3600) % 24, (t / 60) % 60);
 401 }
 402
 403 /**
 404  * The log function for para_server and para_audiod.
 405  *
 406  * \param ll The log level.
 407  * \param fmt The format string describing the log message.
 408  */
 409 __printf_2_3 void daemon_log(int ll, const char* fmt,...)
 410 {
 411         va_list argp;
 412         FILE *fp;
 413         struct tm *tm;
 414         char *color;
 415         bool log_time = daemon_test_flag(DF_LOG_TIME), log_timing =
 416                 daemon_test_flag(DF_LOG_TIMING);
 417
 418         ll = PARA_MIN(ll, NUM_LOGLEVELS - 1);
 419         ll = PARA_MAX(ll, LL_DEBUG);
 420         if (ll < me->loglevel)
 421                 return;
 422
 423         fp = me->logfile? me->logfile : stderr;
 424         if (me->pre_log_hook)
 425                 me->pre_log_hook();
 426         color = daemon_test_flag(DF_COLOR_LOG)? me->log_colors[ll] : NULL;
 427         if (color)
 428                 fprintf(fp, "%s", color);
 429         if (log_time || log_timing) {
 430                 struct timeval tv;
 431                 clock_get_realtime(&tv);
 432                 if (daemon_test_flag(DF_LOG_TIME)) { /* print date and time */
 433                         time_t t1 = tv.tv_sec;
 434                         char str[100];
 435                         tm = localtime(&t1);
 436                         strftime(str, sizeof(str), "%b %d %H:%M:%S", tm);
 437                         fprintf(fp, "%s%s", str, log_timing? ":" : " ");
 438                 }
 439                 if (log_timing) /* print milliseconds */
 440                         fprintf(fp, "%04lu ", (long unsigned)tv.tv_usec / 1000);
 441         }
 442         if (daemon_test_flag(DF_LOG_HOSTNAME)) {
 443                 if (!me->hostname)
 444                         me->hostname = para_hostname();
 445                 fprintf(fp, "%s ", me->hostname);
 446         }
 447         if (daemon_test_flag(DF_LOG_LL)) /* log loglevel */
 448                 fprintf(fp, "(%d) ", ll);
 449         if (daemon_test_flag(DF_LOG_PID)) { /* log pid */
 450                 pid_t mypid = getpid();
 451                 fprintf(fp, "(%d) ", (int)mypid);
 452         }
 453         va_start(argp, fmt);
 454         vfprintf(fp, fmt, argp);
 455         va_end(argp);
 456         if (color)
 457                 fprintf(fp, "%s", COLOR_RESET);
 458         if (me->post_log_hook)
 459                 me->post_log_hook();
 460 }