miscutils/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 #if defined(__GLIBC__)
  32 #include <sys/kdaemon.h>
  33 #else
  34 _syscall2(int, bdflush, int, func, int, data);
  35 #endif                                                  /* __GLIBC__ */
  36
  37 static char update_usage[] =
  38         "update [options]\n\n"
  39         "Periodically flushes filesystem buffers.\n\n"
  40         "Options:\n"
  41         "\t-S\tforce use of sync(2) instead of flushing\n"
  42         "\t-s SECS\tcall sync this often (default 30)\n"
  43         "\t-f SECS\tflush some buffers this often (default 5)\n";
  44
  45 static unsigned int sync_duration = 30;
  46 static unsigned int flush_duration = 5;
  47 static int use_sync = 0;
  48
  49 extern int update_main(int argc, char **argv)
  50 {
  51         int pid;
  52
  53         argc--;
  54         argv++;
  55         while (argc>0 && **argv == '-') {
  56                 while (*++(*argv)) {
  57                         switch (**argv) {
  58                         case 'S':
  59                                 use_sync = 1;
  60                                 break;
  61                         case 's':
  62                                 if (--argc < 1) usage(update_usage);
  63                                 sync_duration = atoi(*(++argv));
  64                                 break;
  65                         case 'f':
  66                                 if (--argc < 1) usage(update_usage);
  67                                 flush_duration = atoi(*(++argv));
  68                                 break;
  69                         default:
  70                                 usage(update_usage);
  71                         }
  72                 }
  73                 argc--;
  74                 argv++;
  75         }
  76
  77         pid = fork();
  78         if (pid < 0)
  79                 exit(FALSE);
  80         else if (pid == 0) {
  81                 /* Become a proper daemon */
  82                 setsid();
  83                 chdir("/");
  84                 for (pid = 0; pid < OPEN_MAX; pid++) close(pid);
  85
  86                 /*
  87                  * This is no longer necessary since 1.3.5x, but it will harmlessly
  88                  * exit if that is the case.
  89                  */
  90                 argv[0] = "bdflush (update)";
  91                 argv[1] = NULL;
  92                 argv[2] = NULL;
  93                 for (;;) {
  94                         if (use_sync) {
  95                                 sleep(sync_duration);
  96                                 sync();
  97                         } else {
  98                                 sleep(flush_duration);
  99                                 if (bdflush(1, 0) < 0) {
 100                                         openlog("update", LOG_CONS, LOG_DAEMON);
 101                                         syslog(LOG_INFO,
 102                                                    "This kernel does not need update(8). Exiting.");
 103                                         closelog();
 104                                         exit(TRUE);
 105                                 }
 106                         }
 107                 }
 108         }
 109         exit( TRUE);
 110 }
 111
 112 /*
 113 Local Variables:
 114 c-file-style: "linux"
 115 c-basic-offset: 4
 116 tab-width: 4
 117 End:
 118 */