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

int contains_byte(char *path, unsigned char byte);

int main(int argc, char *argv[]) {
    if (argc <= 2) {
        fprintf(stderr, "Usage: %s <filename> <byte>\n", argv[0]);
        return 1;
    }
    int byte = strtoul(argv[2], NULL, 0);
    if (contains_byte(argv[1],byte)){
        printf("Contains byte 0x%x\n", byte);
    } else {
        printf("Does not contain byte 0x%x\n", byte);
    }

    return 0;
}

// Return 1 of the  given file contains the given byte.
// Return 0 otherwise
int contains_byte(char *path, unsigned char byte) {
    int f = open(path, O_RDONLY);
    if (f < 0) {
        perror("");
        exit(1);
    }

    //read each byte and compare
    unsigned char c;
    while ((read(f, &c, 1) > 0)){
        if (c == byte) {
            close(f);
            return 1;
        }
    }

    close(f);
    return 0;
}