src/random.c


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#include <s.h>

#include <assert.h>
#include <stdio.h>

#include "random.h"


static FILE *
FH = NULL;


int
random_init(void) {
	int rc = -1;

	FH = fopen("/dev/urandom", "r");
	if (FH == NULL) {
		perror("fopen()");
		goto out;
	}

	rc = 0;
out:
	return rc;
}

int
random_destroy(void) {
	if (FH == NULL) {
		return 0;
	}

	int rc = -1;

	if (fclose(FH)) {
		perror("fclose()");
		goto out;
	}

	rc = 0;
out:
	FH = NULL;
	return rc;
}

static int
random_generate(const unsigned long long length, unsigned char *const out) {
	int rc = -1;

	const size_t read_count = fread(out, 1U, length, FH);
	if (ferror(FH)) {
		perror("fread()");
		goto out;
	}
	assert(read_count == length);

	rc = 0;
out:
	return rc;
}

void
random_bytes(unsigned char *const out, const unsigned long long length) {
	assert(FH != NULL);
	assert(random_generate(length, out) == 0);
}

void
randombytes(unsigned char *const out, const unsigned long long length) {
	random_bytes(out, length);
}