lockf/lockf.c

   1 #include <unistd.h>
   2 #include <fcntl.h>
   3 #include <sys/wait.h>
   4
   5 int main() {
   6     int i, fd = 1;
   7
   8     if (fork()) //il s'agit du père
   9     {
  10         lseek(fd, 0, 0);
  11         if (lockf(fd, F_LOCK, 1) < 0) {
  12             write(fd, "pere lockf failed\n", 18);
  13             return -1;
  14         }
  15         for (i = 0; i < 5; i++) {
  16             write(fd, "pere ecrit\n", 12);
  17             sleep(1);
  18         }
  19         write(fd, "pere va liberer le verrou\n", 26);
  20         lseek(fd, 0, 0);
  21         lockf(fd, F_ULOCK, 0);
  22         wait(NULL);
  23     } else { //il s'agit du fils
  24         lseek(fd, 0, 0); //verrouillé l'octet 0
  25         if (lockf(fd, F_LOCK, 1) < 0) {
  26             write(fd, "fils lockf failed\n", 18);
  27             return -1;
  28         }
  29         for (i = 0; i < 4; i++) {
  30             write(fd, "fils ecrit\n", 12);
  31             sleep(1);
  32         }
  33         write(fd, "fils va liberer le verrou\n", 26);
  34         lseek(fd, 0, 0);
  35         lockf(fd, F_ULOCK, 0);
  36     }
  37     close(fd);
  38     return 0;
  39 }