esp-idf/components/newlib/random.c
2018-08-02 11:02:45 +02:00

53 lines
1.6 KiB
C

// Copyright 2018 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <sys/random.h>
#include <sys/param.h>
#include <assert.h>
#include <errno.h>
#include <string.h>
#include "esp_system.h"
#include "esp_log.h"
static const char *TAG = "RANDOM";
ssize_t getrandom(void *buf, size_t buflen, unsigned int flags)
{
// Flags are ignored because:
// - esp_random is non-blocking so it works for both blocking and non-blocking calls,
// - don't have opportunity so set som other source of entropy.
ESP_LOGD(TAG, "getrandom(buf=0x%x, buflen=%d, flags=%u)", (int) buf, buflen, flags);
if (buf == NULL) {
errno = EFAULT;
ESP_LOGD(TAG, "getrandom returns -1 (EFAULT)");
return -1;
}
uint8_t *dst = (uint8_t *) buf;
ssize_t ret = 0;
while (ret < buflen) {
const uint32_t random = esp_random();
const int needed = buflen - ret;
const int copy_len = MIN(sizeof(random), needed);
memcpy(dst + ret, &random, copy_len);
ret += copy_len;
}
ESP_LOGD(TAG, "getrandom returns %d", ret);
return ret;
}