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
  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 /**
 147  * Do the usual stuff to become a daemon.
 148  *
 149  * Fork, become session leader, dup fd 0, 1, 2 to /dev/null.
 150  *
 151  * \sa fork(2), setsid(2), dup(2).
 152  */
 153 void daemonize(void)
 154 {
 155         pid_t pid;
 156         int null;
 157
 158         PARA_INFO_LOG("daemonizing\n");
 159         pid = fork();
 160         if (pid < 0)
 161                 goto err;
 162         if (pid)
 163                 exit(EXIT_SUCCESS); /* parent exits */
 164         /* become session leader */
 165         if (setsid() < 0)
 166                 goto err;
 167         if (chdir("/") < 0)
 168                 goto err;
 169         null = open("/dev/null", O_RDONLY);
 170         if (null < 0)
 171                 goto err;
 172         if (dup2(null, STDIN_FILENO) < 0)
 173                 goto err;
 174         if (dup2(null, STDOUT_FILENO) < 0)
 175                 goto err;
 176         if (dup2(null, STDERR_FILENO) < 0)
 177                 goto err;
 178         close(null);
 179         return;
 180 err:
 181         PARA_EMERG_LOG("fatal: %s\n", strerror(errno));
 182         exit(EXIT_FAILURE);
 183 }
 184
 185 /**
 186  * Close the log file of the daemon.
 187  */
 188 void daemon_close_log(void)
 189 {
 190         if (!me->logfile)
 191                 return;
 192         PARA_INFO_LOG("closing logfile\n");
 193         fclose(me->logfile);
 194         me->logfile = NULL;
 195 }
 196
 197 /**
 198  * fopen() the logfile in append mode.
 199  *
 200  * \return Either succeeds or exits.
 201  */
 202 void daemon_open_log_or_die(void)
 203 {
 204         daemon_close_log();
 205         if (!me->logfile_name)
 206                 return;
 207         me->logfile = fopen(me->logfile_name, "a");
 208         if (!me->logfile) {
 209                 PARA_EMERG_LOG("can not open %s: %s\n", me->logfile_name,
 210                         strerror(errno));
 211                 exit(EXIT_FAILURE);
 212         }
 213         setlinebuf(me->logfile);
 214 }
 215
 216 /**
 217  * Log the startup message containing the paraslash version.
 218  */
 219 void log_welcome(const char *whoami)
 220 {
 221         PARA_INFO_LOG("welcome to %s " PACKAGE_VERSION " ("BUILD_DATE")\n",
 222                 whoami);
 223 }
 224
 225 /**
 226  * Give up superuser privileges.
 227  *
 228  * \param username The user to switch to.
 229  * \param groupname The group to switch to.
 230  *
 231  * This function returns immediately if not invoked with EUID zero. Otherwise,
 232  * it tries to obtain the GID of \a groupname and the UID of \a username.  On
 233  * success, effective and real GID/UID and the saved set-group-ID/set-user-ID
 234  * are all set accordingly. On errors, an appropriate message is logged and
 235  * exit() is called to terminate the process.
 236  *
 237  * \sa getpwnam(3), getuid(2), setuid(2), getgrnam(2), setgid(2)
 238  */
 239 void drop_privileges_or_die(const char *username, const char *groupname)
 240 {
 241         struct passwd *p;
 242         char *tmp;
 243
 244         if (geteuid())
 245                 return;
 246         if (groupname) {
 247                 struct group *g = getgrnam(groupname);
 248                 if (!g) {
 249                         PARA_EMERG_LOG("failed to get group %s: %s\n",
 250                                 groupname, strerror(errno));
 251                         exit(EXIT_FAILURE);
 252                 }
 253                 if (setgid(g->gr_gid) < 0) {
 254                         PARA_EMERG_LOG("failed to set group id %d: %s\n",
 255                                 (int)g->gr_gid, strerror(errno));
 256                         exit(EXIT_FAILURE);
 257                 }
 258         }
 259         if (!username) {
 260                 PARA_EMERG_LOG("root privileges, but no user option given\n");
 261                 exit(EXIT_FAILURE);
 262         }
 263         tmp = para_strdup(username);
 264         p = getpwnam(tmp);
 265         free(tmp);
 266         if (!p) {
 267                 PARA_EMERG_LOG("%s: no such user\n", username);
 268                 exit(EXIT_FAILURE);
 269         }
 270         PARA_INFO_LOG("dropping root privileges\n");
 271         if (setuid(p->pw_uid) < 0) {
 272                 PARA_EMERG_LOG("failed to set effective user ID (%s)",
 273                         strerror(errno));
 274                 exit(EXIT_FAILURE);
 275         }
 276         PARA_DEBUG_LOG("uid: %d, euid: %d\n", (int)getuid(), (int)geteuid());
 277 }
 278
 279 /**
 280  * Set/get the server uptime.
 281  *
 282  * \param set_or_get Chose one of the two modes.
 283  *
 284  * This should be called at startup time with \a set_or_get equal to \p
 285  * UPTIME_SET which sets the uptime to zero.  Subsequent calls with \a
 286  * set_or_get equal to \p UPTIME_GET return the uptime.
 287
 288  * \return Zero if called with \a set_or_get equal to \p UPTIME_SET, the number
 289  * of seconds elapsed since the last reset otherwise.
 290  *
 291  * \sa time(2), difftime(3).
 292  */
 293 time_t server_uptime(enum uptime set_or_get)
 294 {
 295         time_t now;
 296         double diff;
 297
 298         if (set_or_get == UPTIME_SET) {
 299                 time(&me->startuptime);
 300                 return 0;
 301         }
 302         time(&now);
 303         diff = difftime(now, me->startuptime);
 304         return (time_t) diff;
 305 }
 306
 307 /**
 308  * Construct string containing uptime.
 309  *
 310  * \return A dynamically allocated string of the form "days:hours:minutes".
 311  *
 312  * \sa server_uptime.
 313  */
 314 __malloc char *uptime_str(void)
 315 {
 316         long t = server_uptime(UPTIME_GET);
 317         return make_message("%li:%02li:%02li", t / 86400,
 318                 (t / 3600) % 24, (t / 60) % 60);
 319 }
 320
 321 /**
 322  * The log function for para_server and para_audiod.
 323  *
 324  * \param ll The log level.
 325  * \param fmt The format string describing the log message.
 326  */
 327 __printf_2_3 void para_log(int ll, const char* fmt,...)
 328 {
 329         va_list argp;
 330         FILE *fp;
 331         struct tm *tm;
 332         char *color;
 333         bool log_time = daemon_test_flag(DF_LOG_TIME), log_timing =
 334                 daemon_test_flag(DF_LOG_TIMING);
 335
 336         ll = PARA_MIN(ll, NUM_LOGLEVELS - 1);
 337         ll = PARA_MAX(ll, LL_DEBUG);
 338         if (ll < me->loglevel)
 339                 return;
 340
 341         fp = me->logfile? me->logfile : stderr;
 342         color = daemon_test_flag(DF_COLOR_LOG)? me->log_colors[ll] : NULL;
 343         if (color)
 344                 fprintf(fp, "%s", color);
 345         if (log_time || log_timing) {
 346                 struct timeval tv;
 347                 gettimeofday(&tv, NULL);
 348                 if (daemon_test_flag(DF_LOG_TIME)) { /* print date and time */
 349                         time_t t1 = tv.tv_sec;
 350                         char str[100];
 351                         tm = localtime(&t1);
 352                         strftime(str, sizeof(str), "%b %d %H:%M:%S", tm);
 353                         fprintf(fp, "%s%s", str, log_timing? ":" : " ");
 354                 }
 355                 if (log_timing) /* print milliseconds */
 356                         fprintf(fp, "%04lu ", (long unsigned)tv.tv_usec / 1000);
 357         }
 358         if (daemon_test_flag(DF_LOG_HOSTNAME)) {
 359                 if (!me->hostname)
 360                         me->hostname = para_hostname();
 361                 fprintf(fp, "%s ", me->hostname);
 362         }
 363         if (daemon_test_flag(DF_LOG_LL)) /* log loglevel */
 364                 fprintf(fp, "(%d) ", ll);
 365         if (daemon_test_flag(DF_LOG_PID)) { /* log pid */
 366                 pid_t mypid = getpid();
 367                 fprintf(fp, "(%d) ", (int)mypid);
 368         }
 369         va_start(argp, fmt);
 370         vfprintf(fp, fmt, argp);
 371         va_end(argp);
 372         if (color)
 373                 fprintf(fp, "%s", COLOR_RESET);
 374 }