#include <stdint.h>
#include <limits.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>


#define FILE_NAME "big"
#define GB (1024*1024*1024)
#define PLINE printf("=================================\n")

int try_read(uint64_t size) {
    int exit = 0;

    printf("Trying to get %lld from %s\n", size, FILE_NAME);
    int fd = open(FILE_NAME, O_RDONLY);
    if(fd == -1) {
        printf("open() failed\n");
        exit = -1; goto ex_ret;
    }
    printf("File \"%s\" opened, allocating memory...\n", FILE_NAME);

    char* buffer = (char*)calloc(size, sizeof(char));
    if (!buffer) {
        printf("!! calloc(%lld) failed\n", size);
        exit = -1; goto ex_ret;
    }
    printf("Memory allocated, attempting read...\n");

    int64_t bytesRead = read(fd, buffer, size);
    if (bytesRead == -1) {
        printf("!! read() failed - errno=%d err=%s\n", errno, strerror(errno));
        exit = bytesRead; goto ex_clean;
    }
    printf("Did read %lld bytes ($req-$actual=%lld)\n", bytesRead, (size - bytesRead));

    ex_clean:
    free(buffer);

    ex_ret:
    PLINE;
    return exit;
}

int main() {
    printf("Platform SSIZE_MAX=%ld\n", SSIZE_MAX);
    printf("Platform INT_MAX=%d\n", INT_MAX);
    PLINE;

    try_read((uint64_t)2 * GB);
    try_read((uint64_t)2 * GB - 1);

    return 0;
}