unlinktest.c

// http://twitter.com/ultraistter/statuses/851812566
// gcc unlinktest.c -o unlinktest
// ./ulinktest &
// rm foobar
#include <sys/file.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

#define _UNLINK_CHILD 0
#define TEST_FILE "./foobar"

int main(void)
{
        int fd = open(TEST_FILE, O_RDWR|O_CREAT, S_IWUSR|S_IRUSR);
        int ret;

        if (fd == -1) {
                perror("open");
                return EXIT_FAILURE;
        }
        ret = flock(fd, LOCK_EX);
        if (ret == -1) {
                perror("flock");
                return EXIT_FAILURE;
        }
#if _UNLINK_CHILD
        if (!fork()) {
                ret = unlink(TEST_FILE);
                if (ret == -1) {
                        perror("unlink");
                }
                exit(EXIT_SUCCESS);
        }
#endif
        sleep(10);
        ret = flock(fd, LOCK_UN);
        if (ret == -1) {
                perror("funlock");
        }
        close(fd);

        return EXIT_SUCCESS;
}