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 #include "para.h"
   9 #include "daemon.h"
  10 #include <pwd.h>
  11 #include <sys/types.h> /* getgrnam() */
  12 #include <grp.h>
  13
  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
  26         /** Used by \ref server_uptime() and \ref uptime_str(). */
  27         time_t startuptime;
  28         /** The file pointer if the logfile is open. */
  29         FILE *logfile;
  30         /** Used by para_log() if \p DF_LOG_HOSTNAME is set. */
  31         char *hostname;
  32         /** Used for colored log messages. */
  33         char log_colors[NUM_LOGLEVELS][COLOR_MAXLEN];
  34 };
  35
  36 static struct daemon the_daemon, *me = &the_daemon;
  37
  38 /**
  39  * Activate default log colors.
  40  *
  41  * This should be called early if color support is wanted.
  42  */
  43 void daemon_set_default_log_colors(void)
  44 {
  45         int i;
  46         static const char *default_log_colors[NUM_LOGLEVELS] = {
  47                 [LL_DEBUG] = "normal",
  48                 [LL_INFO] = "normal",
  49                 [LL_NOTICE] = "normal",
  50                 [LL_WARNING] = "yellow",
  51                 [LL_ERROR] = "red",
  52                 [LL_CRIT] = "magenta bold",
  53                 [LL_EMERG] = "red bold",
  54         };
  55         for (i = 0; i < NUM_LOGLEVELS; i++) {
  56                 int ret = color_parse(default_log_colors[i], me->log_colors[i]);
  57                 assert(ret >= 0);
  58         }
  59 }
  60
  61 /**
  62  * Set the color for one loglevel.
  63  *
  64  * \param arg The loglevel/color specifier.
  65  *
  66  * \a arg must be of the form "ll:[fg [bg]] [attr]".
  67  *
  68  * \return 1 On success, -1 on errors.
  69  */
  70 int daemon_set_log_color(char const *arg)
  71 {
  72         char *p = strchr(arg, ':');
  73         int ret, ll;
  74
  75         if (!p)
  76                 goto err;
  77         ret = get_loglevel_by_name(arg);
  78         if (ret < 0)
  79                 goto err;
  80         ll = ret;
  81         p++;
  82         ret = color_parse(p, me->log_colors[ll]);
  83         if (ret < 0)
  84                 goto err;
  85         return 1;
  86 err:
  87         PARA_ERROR_LOG("%s: color syntax error\n", arg);
  88         return -1;
  89
  90 }
  91
  92 /**
  93  * Init or change the name of the log file.
  94  *
  95  * \param logfile_name The full path of the logfile.
  96  */
  97 void daemon_set_logfile(char *logfile_name)
  98 {
  99         free(me->logfile_name);
 100         me->logfile_name = NULL;
 101         if (logfile_name)
 102                 me->logfile_name = para_strdup(logfile_name);
 103 }
 104
 105 /**
 106  * Suppress log messages with severity lower than the given loglevel.
 107  *
 108  * \param loglevel The smallest level that should be logged.
 109  */
 110 void daemon_set_loglevel(char *loglevel)
 111 {
 112         int ret = get_loglevel_by_name(loglevel);
 113
 114         assert(ret >= 0);
 115         me->loglevel = ret;
 116 }
 117
 118 /**
 119  * Set one of the daemon config flags.
 120  *
 121  * \param flag The flag to set.
 122  *
 123  * \sa \ref daemon_flags.
 124  */
 125 void daemon_set_flag(unsigned flag)
 126 {
 127         me->flags |= flag;
 128 }
 129
 130 /**
 131  * Clear one of the daemon config flags.
 132  *
 133  * \param flag The flag to clear.
 134  *
 135  * \sa \ref daemon_flags.
 136  */
 137 void daemon_clear_flag(unsigned flag)
 138 {
 139         me->flags &= ~flag;
 140 }
 141
 142 static unsigned daemon_test_flag(unsigned flag)
 143 {
 144         return me->flags & flag;
 145 }
 146
 147 /**
 148  * Do the usual stuff to become a daemon.
 149  *
 150  * Fork, become session leader, dup fd 0, 1, 2 to /dev/null.
 151  *
 152  * \sa fork(2), setsid(2), dup(2).
 153  */
 154 void daemonize(void)
 155 {
 156         pid_t pid;
 157         int null;
 158
 159         PARA_INFO_LOG("daemonizing\n");
 160         pid = fork();
 161         if (pid < 0)
 162                 goto err;
 163         if (pid)
 164                 exit(EXIT_SUCCESS); /* parent exits */
 165         /* become session leader */
 166         if (setsid() < 0)
 167                 goto err;
 168         if (chdir("/") < 0)
 169                 goto err;
 170         null = open("/dev/null", O_RDONLY);
 171         if (null < 0)
 172                 goto err;
 173         if (dup2(null, STDIN_FILENO) < 0)
 174                 goto err;
 175         if (dup2(null, STDOUT_FILENO) < 0)
 176                 goto err;
 177         if (dup2(null, STDERR_FILENO) < 0)
 178                 goto err;
 179         close(null);
 180         return;
 181 err:
 182         PARA_EMERG_LOG("fatal: %s\n", strerror(errno));
 183         exit(EXIT_FAILURE);
 184 }
 185
 186 /**
 187  * Close the log file of the daemon.
 188  */
 189 void daemon_close_log(void)
 190 {
 191         if (!me->logfile)
 192                 return;
 193         PARA_INFO_LOG("closing logfile\n");
 194         fclose(me->logfile);
 195         me->logfile = NULL;
 196 }
 197
 198 /**
 199  * fopen() the logfile in append mode.
 200  *
 201  * \return Either succeeds or exits.
 202  */
 203 void daemon_open_log_or_die(void)
 204 {
 205         daemon_close_log();
 206         if (!me->logfile_name)
 207                 return;
 208         me->logfile = fopen(me->logfile_name, "a");
 209         if (!me->logfile) {
 210                 PARA_EMERG_LOG("can not open %s: %s\n", me->logfile_name,
 211                         strerror(errno));
 212                 exit(EXIT_FAILURE);
 213         }
 214         setlinebuf(me->logfile);
 215 }
 216
 217 /**
 218  * Log the startup message containing the paraslash version.
 219  */
 220 void log_welcome(const char *whoami)
 221 {
 222         PARA_INFO_LOG("welcome to %s " PACKAGE_VERSION " ("BUILD_DATE")\n",
 223                 whoami);
 224 }
 225
 226 /**
 227  * Give up superuser privileges.
 228  *
 229  * \param username The user to switch to.
 230  * \param groupname The group to switch to.
 231  *
 232  * This function returns immediately if not invoked with EUID zero. Otherwise,
 233  * it tries to obtain the GID of \a groupname and the UID of \a username.  On
 234  * success, effective and real GID/UID and the saved set-group-ID/set-user-ID
 235  * are all set accordingly. On errors, an appropriate message is logged and
 236  * exit() is called to terminate the process.
 237  *
 238  * \sa getpwnam(3), getuid(2), setuid(2), getgrnam(2), setgid(2)
 239  */
 240 void drop_privileges_or_die(const char *username, const char *groupname)
 241 {
 242         struct passwd *p;
 243         char *tmp;
 244
 245         if (geteuid())
 246                 return;
 247         if (groupname) {
 248                 struct group *g = getgrnam(groupname);
 249                 if (!g) {
 250                         PARA_EMERG_LOG("failed to get group %s: %s\n",
 251                                 groupname, strerror(errno));
 252                         exit(EXIT_FAILURE);
 253                 }
 254                 if (setgid(g->gr_gid) < 0) {
 255                         PARA_EMERG_LOG("failed to set group id %d: %s\n",
 256                                 (int)g->gr_gid, strerror(errno));
 257                         exit(EXIT_FAILURE);
 258                 }
 259         }
 260         if (!username) {
 261                 PARA_EMERG_LOG("root privileges, but no user option given\n");
 262                 exit(EXIT_FAILURE);
 263         }
 264         tmp = para_strdup(username);
 265         p = getpwnam(tmp);
 266         free(tmp);
 267         if (!p) {
 268                 PARA_EMERG_LOG("%s: no such user\n", username);
 269                 exit(EXIT_FAILURE);
 270         }
 271         PARA_INFO_LOG("dropping root privileges\n");
 272         setuid(p->pw_uid);
 273         PARA_DEBUG_LOG("uid: %d, euid: %d\n", (int)getuid(), (int)geteuid());
 274 }
 275
 276 /**
 277  * Set/get the server uptime.
 278  *
 279  * \param set_or_get Chose one of the two modes.
 280  *
 281  * This should be called at startup time with \a set_or_get equal to \p
 282  * UPTIME_SET which sets the uptime to zero.  Subsequent calls with \a
 283  * set_or_get equal to \p UPTIME_GET return the uptime.
 284
 285  * \return Zero if called with \a set_or_get equal to \p UPTIME_SET, the number
 286  * of seconds elapsed since the last reset otherwise.
 287  *
 288  * \sa time(2), difftime(3).
 289  */
 290 time_t server_uptime(enum uptime set_or_get)
 291 {
 292         time_t now;
 293         double diff;
 294
 295         if (set_or_get == UPTIME_SET) {
 296                 time(&me->startuptime);
 297                 return 0;
 298         }
 299         time(&now);
 300         diff = difftime(now, me->startuptime);
 301         return (time_t) diff;
 302 }
 303
 304 /**
 305  * Construct string containing uptime.
 306  *
 307  * \return A dynamically allocated string of the form "days:hours:minutes".
 308  *
 309  * \sa server_uptime.
 310  */
 311 __malloc char *uptime_str(void)
 312 {
 313         long t = server_uptime(UPTIME_GET);
 314         return make_message("%li:%02li:%02li", t / 86400,
 315                 (t / 3600) % 24, (t / 60) % 60);
 316 }
 317
 318 /**
 319  * The log function for para_server and para_audiod.
 320  *
 321  * \param ll The log level.
 322  * \param fmt The format string describing the log message.
 323  */
 324 __printf_2_3 void para_log(int ll, const char* fmt,...)
 325 {
 326         va_list argp;
 327         FILE *fp;
 328         struct tm *tm;
 329         time_t t1;
 330         char *color, str[MAXLINE] = "";
 331
 332         ll = PARA_MIN(ll, NUM_LOGLEVELS - 1);
 333         ll = PARA_MAX(ll, LL_DEBUG);
 334         if (ll < me->loglevel)
 335                 return;
 336
 337         fp = me->logfile? me->logfile : stderr;
 338         color = daemon_test_flag(DF_COLOR_LOG)? me->log_colors[ll] : NULL;
 339         if (color)
 340                 fprintf(fp, "%s", color);
 341         if (daemon_test_flag(DF_LOG_TIME)) {
 342                 /* date and time */
 343                 time(&t1);
 344                 tm = localtime(&t1);
 345                 strftime(str, MAXLINE, "%b %d %H:%M:%S", tm);
 346                 fprintf(fp, "%s ", str);
 347         }
 348         if (daemon_test_flag(DF_LOG_HOSTNAME)) {
 349                 if (!me->hostname)
 350                         me->hostname = para_hostname();
 351                 fprintf(fp, "%s ", me->hostname);
 352         }
 353         if (daemon_test_flag(DF_LOG_LL)) /* log loglevel */
 354                 fprintf(fp, "(%d) ", ll);
 355         if (daemon_test_flag(DF_LOG_PID)) { /* log pid */
 356                 pid_t mypid = getpid();
 357                 fprintf(fp, "(%d) ", (int)mypid);
 358         }
 359         va_start(argp, fmt);
 360         vfprintf(fp, fmt, argp);
 361         va_end(argp);
 362         if (color)
 363                 fprintf(fp, "%s", COLOR_RESET);
 364 }