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