lock file twice

lock.cc

# Compile with g++ -o lock lock.cc

#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>

int main()
{
    int fd, fd2 , ret;
    struct flock strlock;
    fd = open("testfile", O_CREAT | O_RDWR , 0666 );
    if (fd == -1)
    {
      printf("FATAL ERROR: Could not open file\n");
      exit(-1);
    }
    strlock.l_type = F_WRLCK;
    strlock.l_whence = SEEK_SET;
    strlock.l_start = 0L;
    strlock.l_len = 0L;
    ret = fcntl (fd, F_SETLK , &strlock);
    if (ret == -1)
    {
      printf("FATAL ERROR: Could not lock file\n");
      exit(-1);
    }
    fd2 = open("testfile", O_RDWR , 0666 );
    if (fd2 == -1)
    {
    printf("FATAL ERROR: Could not open file\n");
    exit(-1);
    }
    strlock.l_type = F_WRLCK;
    strlock.l_whence = SEEK_SET;
    strlock.l_start = 0L;
    strlock.l_len = 0L;
    ret = fcntl (fd2, F_SETLK , &strlock);
    if (ret == -1)
    {
      printf("FATAL ERROR: Could not lock file\n");
      exit(-1);
    }
    ret = close( fd );
    if (ret == -1)
    {
      printf("FATAL ERROR: Could not close file\n");
      exit(-1);
    }
    ret = close( fd2 );
    if (ret == -1)
    {
      printf("FATAL ERROR: Could not close file\n");
      exit(-1);
    }
}