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

void print_to_start(char *path, unsigned char byte);

int main(int argc, char *argv[]) {
    if (argc <= 2) {
        fprintf(stderr, "Usage: %s <filename> <string>\n", argv[0]);
        return 1;
    }
    unsigned char byte = strtoul(argv[2], NULL, 0);
    print_to_start(argv[1],byte);

    return 0;
}

// Add the given byte to the beginning of the given file
// You may use a temp file
void print_to_start(char *path, unsigned char byte){
    FILE *file_reader = fopen(path, "r");
    FILE *tmp_writer = fopen("f.tmp", "w");

    fputc(byte, tmp_writer);

    int curr_byte;
    while ((curr_byte = fgetc(file_reader)) != EOF) {
        fputc(curr_byte, tmp_writer);
    }

    fclose(file_reader);
    fclose(tmp_writer);
    
    //rename("f.tmp", path);
    FILE *file_writer = fopen(path, "w");
    FILE *tmp_reader = fopen("f.tmp", "r");

    while ((curr_byte = fgetc(tmp_reader)) != EOF) {
        fputc(curr_byte, file_writer);
    }
    fclose(file_writer);
    fclose(tmp_reader);

}