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

void
usage(void)
{
    printf("Usage: testlock <filepath> [R|W]\n");
    return;
}

int
main(int argc, char *argv[])
{
    char *file_path = NULL;
    int fd = -1;
    struct flock lock = {0};
    int ret = -1;
    int c = 0;

    if (argc != 3) {
        usage();
        exit(1);
    }

    file_path = argv[1];
    fd = open(file_path, O_RDWR);

    if (-1 == fd) {
        printf("Failed to open file %s. %m\n", file_path);
        exit(1);
    }

    /* TODO: Check for invalid input*/

    if (!strcmp(argv[2], "W")) {
        lock.l_type = F_WRLCK;
        printf("Taking write lock\n");

    } else {
        lock.l_type = F_RDLCK;
        printf("Taking read lock\n");
    }

    lock.l_whence = SEEK_SET;
    lock.l_start = 0;
    lock.l_len = 0;
    lock.l_pid = getpid();

    printf("Acquiring lock on %s\n", file_path);
    ret = fcntl(fd, F_SETLK, &lock);
    if (ret) {
        printf("Failed to acquire lock on %s (%m)\n", file_path);
        close(fd);
        exit(1);
    }

    sleep(10);

    /*Unlock*/

    printf("Releasing lock on %s\n", file_path);
    lock.l_type = F_UNLCK;
    ret = fcntl(fd, F_SETLK, &lock);
    if (ret) {
        printf("Failed to release lock on %s (%m)\n", file_path);
    }

    close(fd);
    return ret;
}
