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 #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                 int ret = color_parse(default_log_colors[i], me->log_colors[i]);
  61                 assert(ret >= 0);
  62         }
  63 }
  64
  65 /**
  66  * Set the color for one loglevel.
  67  *
  68  * \param arg The loglevel/color specifier.
  69  *
  70  * \a arg must be of the form "ll:[fg [bg]] [attr]".
  71  *
  72  * \return 1 On success, -1 on errors.
  73  */
  74 int daemon_set_log_color(char const *arg)
  75 {
  76         char *p = strchr(arg, ':');
  77         int ret, ll;
  78
  79         if (!p)
  80                 goto err;
  81         ret = get_loglevel_by_name(arg);
  82         if (ret < 0)
  83                 goto err;
  84         ll = ret;
  85         p++;
  86         ret = color_parse(p, me->log_colors[ll]);
  87         if (ret < 0)
  88                 goto err;
  89         return 1;
  90 err:
  91         PARA_ERROR_LOG("%s: color syntax error\n", arg);
  92         return -1;
  93
  94 }
  95
  96 /**
  97  * Init or change the name of the log file.
  98  *
  99  * \param logfile_name The full path of the logfile.
 100  */
 101 void daemon_set_logfile(char *logfile_name)
 102 {
 103         free(me->logfile_name);
 104         me->logfile_name = NULL;
 105         if (logfile_name)
 106                 me->logfile_name = para_strdup(logfile_name);
 107 }
 108
 109 /**
 110  * Suppress log messages with severity lower than the given loglevel.
 111  *
 112  * \param loglevel The smallest level that should be logged.
 113  */
 114 void daemon_set_loglevel(char *loglevel)
 115 {
 116         int ret = get_loglevel_by_name(loglevel);
 117
 118         assert(ret >= 0);
 119         me->loglevel = ret;
 120 }
 121
 122 /**
 123  * Set one of the daemon config flags.
 124  *
 125  * \param flag The flag to set.
 126  *
 127  * \sa \ref daemon_flags.
 128  */
 129 void daemon_set_flag(unsigned flag)
 130 {
 131         me->flags |= flag;
 132 }
 133
 134 /**
 135  * Clear one of the daemon config flags.
 136  *
 137  * \param flag The flag to clear.
 138  *
 139  * \sa \ref daemon_flags.
 140  */
 141 void daemon_clear_flag(unsigned flag)
 142 {
 143         me->flags &= ~flag;
 144 }
 145
 146 static bool daemon_test_flag(unsigned flag)
 147 {
 148         return me->flags & flag;
 149 }
 150
 151 /**
 152  * Do the usual stuff to become a daemon.
 153  *
 154  * Fork, become session leader, dup fd 0, 1, 2 to /dev/null.
 155  *
 156  * \sa fork(2), setsid(2), dup(2).
 157  */
 158 void daemonize(void)
 159 {
 160         pid_t pid;
 161         int null;
 162
 163         PARA_INFO_LOG("daemonizing\n");
 164         pid = fork();
 165         if (pid < 0)
 166                 goto err;
 167         if (pid)
 168                 exit(EXIT_SUCCESS); /* parent exits */
 169         /* become session leader */
 170         if (setsid() < 0)
 171                 goto err;
 172         if (chdir("/") < 0)
 173                 goto err;
 174         null = open("/dev/null", O_RDONLY);
 175         if (null < 0)
 176                 goto err;
 177         if (dup2(null, STDIN_FILENO) < 0)
 178                 goto err;
 179         if (dup2(null, STDOUT_FILENO) < 0)
 180                 goto err;
 181         if (dup2(null, STDERR_FILENO) < 0)
 182                 goto err;
 183         close(null);
 184         return;
 185 err:
 186         PARA_EMERG_LOG("fatal: %s\n", strerror(errno));
 187         exit(EXIT_FAILURE);
 188 }
 189
 190 /**
 191  * Close the log file of the daemon.
 192  */
 193 void daemon_close_log(void)
 194 {
 195         if (!me->logfile)
 196                 return;
 197         PARA_INFO_LOG("closing logfile\n");
 198         fclose(me->logfile);
 199         me->logfile = NULL;
 200 }
 201
 202 /**
 203  * fopen() the logfile in append mode.
 204  *
 205  * \return Either succeeds or exits.
 206  */
 207 void daemon_open_log_or_die(void)
 208 {
 209         daemon_close_log();
 210         if (!me->logfile_name)
 211                 return;
 212         me->logfile = fopen(me->logfile_name, "a");
 213         if (!me->logfile) {
 214                 PARA_EMERG_LOG("can not open %s: %s\n", me->logfile_name,
 215                         strerror(errno));
 216                 exit(EXIT_FAILURE);
 217         }
 218         setlinebuf(me->logfile);
 219 }
 220
 221 /**
 222  * Log the startup message containing the paraslash version.
 223  */
 224 void log_welcome(const char *whoami)
 225 {
 226         PARA_INFO_LOG("welcome to %s " PACKAGE_VERSION " ("BUILD_DATE")\n",
 227                 whoami);
 228 }
 229
 230 /**
 231  * Give up superuser privileges.
 232  *
 233  * \param username The user to switch to.
 234  * \param groupname The group to switch to.
 235  *
 236  * This function returns immediately if not invoked with EUID zero. Otherwise,
 237  * it tries to obtain the GID of \a groupname and the UID of \a username.  On
 238  * success, effective and real GID/UID and the saved set-group-ID/set-user-ID
 239  * are all set accordingly. On errors, an appropriate message is logged and
 240  * exit() is called to terminate the process.
 241  *
 242  * \sa getpwnam(3), getuid(2), setuid(2), getgrnam(2), setgid(2)
 243  */
 244 void drop_privileges_or_die(const char *username, const char *groupname)
 245 {
 246         struct passwd *p;
 247         char *tmp;
 248
 249         if (geteuid())
 250                 return;
 251         if (groupname) {
 252                 struct group *g = getgrnam(groupname);
 253                 if (!g) {
 254                         PARA_EMERG_LOG("failed to get group %s: %s\n",
 255                                 groupname, strerror(errno));
 256                         exit(EXIT_FAILURE);
 257                 }
 258                 if (setgid(g->gr_gid) < 0) {
 259                         PARA_EMERG_LOG("failed to set group id %d: %s\n",
 260                                 (int)g->gr_gid, strerror(errno));
 261                         exit(EXIT_FAILURE);
 262                 }
 263         }
 264         if (!username) {
 265                 PARA_EMERG_LOG("root privileges, but no user option given\n");
 266                 exit(EXIT_FAILURE);
 267         }
 268         tmp = para_strdup(username);
 269         p = getpwnam(tmp);
 270         free(tmp);
 271         if (!p) {
 272                 PARA_EMERG_LOG("%s: no such user\n", username);
 273                 exit(EXIT_FAILURE);
 274         }
 275         PARA_INFO_LOG("dropping root privileges\n");
 276         if (setuid(p->pw_uid) < 0) {
 277                 PARA_EMERG_LOG("failed to set effective user ID (%s)",
 278                         strerror(errno));
 279                 exit(EXIT_FAILURE);
 280         }
 281         PARA_DEBUG_LOG("uid: %d, euid: %d\n", (int)getuid(), (int)geteuid());
 282 }
 283
 284 /**
 285  * Set/get the server uptime.
 286  *
 287  * \param set_or_get Chose one of the two modes.
 288  *
 289  * This should be called at startup time with \a set_or_get equal to \p
 290  * UPTIME_SET which sets the uptime to zero.  Subsequent calls with \a
 291  * set_or_get equal to \p UPTIME_GET return the uptime.
 292
 293  * \return Zero if called with \a set_or_get equal to \p UPTIME_SET, the number
 294  * of seconds elapsed since the last reset otherwise.
 295  *
 296  * \sa time(2), difftime(3).
 297  */
 298 time_t server_uptime(enum uptime set_or_get)
 299 {
 300         time_t now;
 301         double diff;
 302
 303         if (set_or_get == UPTIME_SET) {
 304                 time(&me->startuptime);
 305                 return 0;
 306         }
 307         time(&now);
 308         diff = difftime(now, me->startuptime);
 309         return (time_t) diff;
 310 }
 311
 312 /**
 313  * Construct string containing uptime.
 314  *
 315  * \return A dynamically allocated string of the form "days:hours:minutes".
 316  *
 317  * \sa server_uptime.
 318  */
 319 __malloc char *uptime_str(void)
 320 {
 321         long t = server_uptime(UPTIME_GET);
 322         return make_message("%li:%02li:%02li", t / 86400,
 323                 (t / 3600) % 24, (t / 60) % 60);
 324 }
 325
 326 /**
 327  * The log function for para_server and para_audiod.
 328  *
 329  * \param ll The log level.
 330  * \param fmt The format string describing the log message.
 331  */
 332 __printf_2_3 void para_log(int ll, const char* fmt,...)
 333 {
 334         va_list argp;
 335         FILE *fp;
 336         struct tm *tm;
 337         char *color;
 338         bool log_time = daemon_test_flag(DF_LOG_TIME), log_timing =
 339                 daemon_test_flag(DF_LOG_TIMING);
 340
 341         ll = PARA_MIN(ll, NUM_LOGLEVELS - 1);
 342         ll = PARA_MAX(ll, LL_DEBUG);
 343         if (ll < me->loglevel)
 344                 return;
 345
 346         fp = me->logfile? me->logfile : stderr;
 347         color = daemon_test_flag(DF_COLOR_LOG)? me->log_colors[ll] : NULL;
 348         if (color)
 349                 fprintf(fp, "%s", color);
 350         if (log_time || log_timing) {
 351                 struct timeval tv;
 352                 gettimeofday(&tv, NULL);
 353                 if (daemon_test_flag(DF_LOG_TIME)) { /* print date and time */
 354                         time_t t1 = tv.tv_sec;
 355                         char str[100];
 356                         tm = localtime(&t1);
 357                         strftime(str, sizeof(str), "%b %d %H:%M:%S", tm);
 358                         fprintf(fp, "%s%s", str, log_timing? ":" : " ");
 359                 }
 360                 if (log_timing) /* print milliseconds */
 361                         fprintf(fp, "%04lu ", (long unsigned)tv.tv_usec / 1000);
 362         }
 363         if (daemon_test_flag(DF_LOG_HOSTNAME)) {
 364                 if (!me->hostname)
 365                         me->hostname = para_hostname();
 366                 fprintf(fp, "%s ", me->hostname);
 367         }
 368         if (daemon_test_flag(DF_LOG_LL)) /* log loglevel */
 369                 fprintf(fp, "(%d) ", ll);
 370         if (daemon_test_flag(DF_LOG_PID)) { /* log pid */
 371                 pid_t mypid = getpid();
 372                 fprintf(fp, "(%d) ", (int)mypid);
 373         }
 374         va_start(argp, fmt);
 375         vfprintf(fp, fmt, argp);
 376         va_end(argp);
 377         if (color)
 378                 fprintf(fp, "%s", COLOR_RESET);
 379 }