#define _GNU_SOURCE /* Required for linux fallocate */
#include <fcntl.h>
#include <linux/falloc.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int posix_falloc(void);
int file_trunc(void);
int linux_falloc(void);

#define FILENAME "allocated.bin"

int main(void) {
    posix_falloc();
    file_trunc();
    linux_falloc();

    return EXIT_SUCCESS;
}

int posix_falloc(void) {
    int fd = open(FILENAME, O_CREAT | O_WRONLY, 0666);
    if (fd == -1) {
        return EXIT_FAILURE;
    }

    off_t length = 1024 * 1024; // 1 MB
    int   ret = posix_fallocate(fd, 0, length);
    if (ret != 0) {
        return EXIT_FAILURE;
    }

    close(fd);
    remove(FILENAME);
    return EXIT_SUCCESS;
}

int linux_falloc(void) {
    int fd = open(FILENAME, O_CREAT | O_WRONLY, 0666);
    if (fd == -1) {
        perror("Error");
        return EXIT_FAILURE;
    }

    off_t length = 1024 * 1024; // 1 MB
    if (fallocate(fd, 0, 0, length) == -1) {
        perror("fallocate");
        return EXIT_FAILURE;
    }

    close(fd);
    remove(FILENAME);
    return EXIT_SUCCESS;
}

int file_trunc(void) {
    int fd = open(FILENAME, O_CREAT | O_WRONLY, 0666);
    if (fd == -1) {
        perror("Error");
        return EXIT_FAILURE;
    }
    off_t length = 1024 * 1024; // 1 MB
    ftruncate(fd, length);
    remove(FILENAME);
    return EXIT_SUCCESS;
}