Generate random numbers from /dev/urandom

urandom_test.c

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

#define MAX 36
#define URANDOM_DEVICE "/dev/urandom"

static FILE *urandom;

/*
 * Returns a random number from 0 to MAX-1
 */
int random_number(void) {
    int c;
    do {
        c = fgetc(urandom);
        if (c == EOF) {
            fprintf(stderr, "Failed to read from %s\n", URANDOM_DEVICE);
            exit(EXIT_FAILURE);
        }
    }
    while (c >= (UCHAR_MAX + 1) / MAX * MAX);

    return c % MAX;
}

int main(void) {
    urandom = fopen(URANDOM_DEVICE, "rb");
    if (urandom == NULL) {
        fprintf(stderr, "Failed to open %s\n", URANDOM_DEVICE);
        exit(EXIT_FAILURE);
    }

    for (int i = 0; i < 10; i ++) {
        printf("%d\n", random_number());
    }
    fclose(urandom);
    return 0;
}

Hi, I saw your comment, but I'm not sure what you're saying.

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