#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

enum { BUFFER_SIZE = 4096 };

ssize_t read_BUFF(int in_fd, char *buffer) {
    ssize_t count_read = 0;
    while (count_read != BUFFER_SIZE) {
        ssize_t read_bytes = read(in_fd, buffer + count_read,
            BUFFER_SIZE - count_read);
        if (read_bytes == -1) {
            return -1;
        }
        if (read_bytes == 0) {
            return count_read;
        }
        count_read += read_bytes;
    }
    return BUFFER_SIZE;
}

struct FileContent read_file(int fd) {
    errno = !ENOMEM;
    struct FileContent returned;
    char buffer[BUFFER_SIZE];

    char *data = malloc(sizeof(*data));
    if (errno == ENOMEM) {
        free(data);
        returned.size = -1;
        returned.data = NULL;
        return returned;
    }
    size_t cur_mal = 1;

    if (data == NULL) {
        free(data);
        returned.size = -1;
        returned.data = NULL;
        return returned;
    }

    ssize_t read = 1;
    ssize_t current_read = 0;
    while (read > 0) {
        read = read_BUFF(fd, buffer);
        if (read == -1) {
            free(data);
            returned.size = -1;
            returned.data = NULL;
            return returned;
        }
        while (current_read + read >= cur_mal) {
            char *data1;
            data1 = realloc(data, (cur_mal *= 2) * sizeof(*data));
            if (data1 == NULL) {
                free(data);
                returned.size = -1;
                returned.data = NULL;
                return returned;
            } else {
                data = data1;
            }
            if (errno == ENOMEM) {
                free(data);
                returned.size = -1;
                returned.data = NULL;
                return returned;
            }
        }
        memcpy(data + current_read, buffer, read);
        current_read += read;
    }
    returned.size = current_read;
    data[current_read] = 0;
    returned.data = data;
    return returned;
}