experiment4.c

   1 #include <stdio.h>
   2 #include <sys/types.h>
   3 #include <sys/stat.h>
   4 #include <fcntl.h>
   5 #include <unistd.h>
   6 #include <stdlib.h>
   7 #include <errno.h>
   8 #include <string.h>
   9 #include <sys/file.h>
  10
  11
  12 int main() {
  13     FILE *fd;
  14     char mac[13];
  15     unsigned long int counter = 0;
  16
  17     int locker = open("/mnt/netapp/maccounter", O_RDWR | O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
  18     flock(locker, LOCK_EX);
  19
  20     if ((fd = fdopen(locker, "w+")) != NULL) {
  21         if (fread(mac, 12, sizeof(char), fd) == 1) {
  22             mac[12] = '\0';
  23             counter = strtoul(mac, NULL, 16);
  24             counter++;
  25         }
  26         snprintf(mac, 13, "%012lX\n", counter);
  27         rewind(fd);
  28         fwrite(mac, 12, sizeof(char), fd);
  29         fclose(fd);
  30
  31         char pretty[18];
  32         pretty[2] = ':'; pretty[5] = ':'; pretty[8] = ':'; pretty[11] = ':'; pretty[14] = ':'; pretty[17] = '\0';
  33         strncpy(&pretty[0], &mac[0], 2);
  34         strncpy(&pretty[3], &mac[2], 2);
  35         strncpy(&pretty[6], &mac[4], 2);
  36         strncpy(&pretty[9], &mac[6], 2);
  37         strncpy(&pretty[12], &mac[8], 2);
  38         strncpy(&pretty[15], &mac[10], 2);
  39
  40         // dhcp-host=00:1E:C9:B3:B3:85,xen001.xen,172.16.103.1,24h
  41         printf("dhcp-host=%s,%s.xen,...,24h\n", pretty, "test");
  42
  43 //        fd = fopen("/mnt/netapp/dnsmasq.conf", "a");
  44 //        fprintf(fd, "dhcp-host=%s,%s,", 10, sizeof(char)
  45 //        fclose(fd);
  46     }
  47
  48     flock(locker, LOCK_UN);
  49     close(locker);
  50
  51     return 0;
  52 }