#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>

void bail(const char* message)
{
    printf("%s\n", message);
    exit(1);
}

int detect(unsigned char* fptr, size_t size)
{
    for (size_t i = 0; i < size; ++i)
    {
        if (fptr[i]) return i;
    }
    return 0;
}

int main(int argc, char* argv[])
{
    struct stat status;
    int desc = 0;
    void* fptr = NULL;
    if ( argc != 2 ) bail("Invalid arguments.");

    if ( stat(argv[1], &status) ) bail("stat() failed.");

    desc = open(argv[1], O_RDONLY);
    if ( desc == -1 ) bail("open() failed.");

    fptr = mmap(0, status.st_size, PROT_READ, MAP_SHARED, desc, 0);
    if ( fptr == MAP_FAILED ) bail("mmap() failed.");

    if ( close(desc) ) bail("close() failed.");

    if ( detect(fptr, status.st_size) ) bail("file might be corrupt.");

    if ( munmap(fptr, status.st_size) ) bail("munmap() failed.");

    return 0;
}