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#include "config.h"
#include <assert.h>
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include "logerr.h"
#include "random.h"
int
urandom_bytes(const size_t n, uint8_t (*const addr)[]) {
int rc = 0;
FILE *f = NULL;
f = fopen("/dev/urandom", "r");
if (!f) {
logerr("fopen(\"/dev/urandom\", \"r\"): %s\n", strerror(errno));
rc = -1;
goto out;
}
const size_t read_count = fread(addr, 1, n, f);
if (ferror(f)) {
logerr("fread(addr, 1, n, f): %s\n", strerror(errno));
rc = -1;
goto out;
}
assert(read_count == n);
out:
if (f) {
if (fclose(f)) {
logerr("fclose(f): %s\n", strerror(errno));
rc = -1;
}
}
return rc;
}
#ifdef TEST
#include "testing.h"
static int
test_urandom_bytes(void) {
int rc = 0;
test_start("urandom_bytes()");
{
testing("we get to pick the size that comes out");
const size_t LEN = 256;
uint8_t arr[256 /* LEN */] = { 0 };
for (size_t n = 0; n < LEN; n++) {
if (urandom_bytes(n, &arr)) {
logerr("urandom_bytes(n, &arr);\n");
rc = -1;
goto out;
}
for (size_t i = n; i < LEN; i++) {
assert(arr[i] == 0);
}
}
test_ok();
}
{
testing("we always get a new value as a result");
const size_t LEN = 64;
uint8_t arr1[64 /* LEN */] = { 0 };
uint8_t arr2[64 /* LEN */] = { 0 };
if (urandom_bytes(LEN, &arr1)) {
logerr("urandom_bytes(LEN, &arr1);\n");
rc = -1;
goto out;
}
const size_t attempts = 10;
for (size_t n = 0; n < attempts; n++) {
if (urandom_bytes(LEN, &arr2)) {
logerr("urandom_bytes(LEN, &arr2);\n");
rc = -1;
goto out;
}
assert(memcmp(arr1, arr2, LEN) != 0);
}
test_ok();
}
out:
return rc;
}
int
main(void) {
int rc = 0;
if (test_urandom_bytes()) {
logerr("test_urandom_bytes();\n");
rc = -1;
goto out;
}
out:
return !!rc;
}
#endif
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