update.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini update implementation for busybox; much pasted from update-2.11
   4  *
   5  *
   6  * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
   7  * Copyright (c) 1996, 1997, 1999 Torsten Poulin.
   8  * Copyright (c) 2000 by Karl M. Hegbloom <karlheg@debian.org>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18  * General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  23  *
  24  */
  25
  26 #include "internal.h"
  27 #include <linux/unistd.h>
  28 #include <sys/param.h>
  29 #include <sys/syslog.h>
  30
  31
  32 #if defined(__GLIBC__)
  33 #include <sys/kdaemon.h>
  34 #else
  35 static _syscall2(int, bdflush, int, func, int, data);
  36 #endif                                                  /* __GLIBC__ */
  37
  38
  39 static char update_usage[] =
  40         "update [options]\n"
  41 #ifndef BB_FEATURE_TRIVIAL_HELP
  42         "\nPeriodically flushes filesystem buffers.\n\n"
  43         "Options:\n"
  44         "\t-S\tforce use of sync(2) instead of flushing\n"
  45         "\t-s SECS\tcall sync this often (default 30)\n"
  46         "\t-f SECS\tflush some buffers this often (default 5)\n"
  47 #endif
  48         ;
  49
  50 static unsigned int sync_duration = 30;
  51 static unsigned int flush_duration = 5;
  52 static int use_sync = 0;
  53
  54 extern int update_main(int argc, char **argv)
  55 {
  56         int pid;
  57
  58         argc--;
  59         argv++;
  60         while (argc>0 && **argv == '-') {
  61                 while (*++(*argv)) {
  62                         switch (**argv) {
  63                         case 'S':
  64                                 use_sync = 1;
  65                                 break;
  66                         case 's':
  67                                 if (--argc < 1) usage(update_usage);
  68                                 sync_duration = atoi(*(++argv));
  69                                 break;
  70                         case 'f':
  71                                 if (--argc < 1) usage(update_usage);
  72                                 flush_duration = atoi(*(++argv));
  73                                 break;
  74                         default:
  75                                 usage(update_usage);
  76                         }
  77                 }
  78                 argc--;
  79                 argv++;
  80         }
  81
  82         pid = fork();
  83         if (pid < 0)
  84                 exit(FALSE);
  85         else if (pid == 0) {
  86                 /* Become a proper daemon */
  87                 setsid();
  88                 chdir("/");
  89                 for (pid = 0; pid < OPEN_MAX; pid++) close(pid);
  90
  91                 /*
  92                  * This is no longer necessary since 1.3.5x, but it will harmlessly
  93                  * exit if that is the case.
  94                  */
  95                 argv[0] = "bdflush (update)";
  96                 argv[1] = NULL;
  97                 argv[2] = NULL;
  98                 for (;;) {
  99                         if (use_sync) {
 100                                 sleep(sync_duration);
 101                                 sync();
 102                         } else {
 103                                 sleep(flush_duration);
 104                                 if (bdflush(1, 0) < 0) {
 105                                         openlog("update", LOG_CONS, LOG_DAEMON);
 106                                         syslog(LOG_INFO,
 107                                                    "This kernel does not need update(8). Exiting.");
 108                                         closelog();
 109                                         exit(TRUE);
 110                                 }
 111                         }
 112                 }
 113         }
 114         return( TRUE);
 115 }
 116
 117 /*
 118 Local Variables:
 119 c-file-style: "linux"
 120 c-basic-offset: 4
 121 tab-width: 4
 122 End:
 123 */