/*
 * Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License"). You may not use
 * this file except in compliance with the License. You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <stdio.h>
#include "internal/cryptlib.h"
#include <openssl/buffer.h>

/*
 * LIMIT_BEFORE_EXPANSION is the maximum n such that (n+3)/3*4 < 2**31. That
 * function is applied in several functions in this file and this limit
 * ensures that the result fits in an int.
 */
#define LIMIT_BEFORE_EXPANSION 0x5ffffffc

BUF_MEM *BUF_MEM_new_ex(unsigned long flags)
{
 BUF_MEM *ret;

 ret = BUF_MEM_new();
 if (ret != NULL)
 ret->flags = flags;
 return ret;
}

BUF_MEM *BUF_MEM_new(void)
{
 BUF_MEM *ret;

 ret = OPENSSL_zalloc(sizeof(*ret));
 if (ret == NULL)
 return NULL;
 return ret;
}

void BUF_MEM_free(BUF_MEM *a)
{
 if (a == NULL)
 return;
 if (a->data != NULL) {
 if (a->flags & BUF_MEM_FLAG_SECURE)
 OPENSSL_secure_clear_free(a->data, a->max);
 else
 OPENSSL_clear_free(a->data, a->max);
 }
 OPENSSL_free(a);
}

/* Allocate a block of secure memory; copy over old data if there
 * was any, and then free it. */
static char *sec_alloc_realloc(BUF_MEM *str, size_t len)
{
 char *ret;

 ret = OPENSSL_secure_malloc(len);
 if (str->data != NULL) {
 if (ret != NULL) {
 memcpy(ret, str->data, str->length);
 OPENSSL_secure_clear_free(str->data, str->length);
 str->data = NULL;
 }
 }
 return ret;
}

size_t BUF_MEM_grow(BUF_MEM *str, size_t len)
{
 char *ret;
 size_t n;

 if (str->length >= len) {
 str->length = len;
 return len;
 }
 if (str->max >= len) {
 if (str->data != NULL)
 memset(&str->data[str->length], 0, len - str->length);
 str->length = len;
 return len;
 }
 /* This limit is sufficient to ensure (len+3)/3*4 < 2**31 */
 if (len > LIMIT_BEFORE_EXPANSION) {
 ERR_raise(ERR_LIB_BUF, ERR_R_PASSED_INVALID_ARGUMENT);
 return 0;
 }
 n = (len + 3) / 3 * 4;
 if ((str->flags & BUF_MEM_FLAG_SECURE))
 ret = sec_alloc_realloc(str, n);
 else
 ret = OPENSSL_realloc(str->data, n);
 if (ret == NULL) {
 len = 0;
 } else {
 str->data = ret;
 str->max = n;
 memset(&str->data[str->length], 0, len - str->length);
 str->length = len;
 }
 return len;
}

size_t BUF_MEM_grow_clean(BUF_MEM *str, size_t len)
{
 char *ret;
 size_t n;

 if (str->length >= len) {
 if (str->data != NULL)
 memset(&str->data[len], 0, str->length - len);
 str->length = len;
 return len;
 }
 if (str->max >= len) {
 memset(&str->data[str->length], 0, len - str->length);
 str->length = len;
 return len;
 }
 /* This limit is sufficient to ensure (len+3)/3*4 < 2**31 */
 if (len > LIMIT_BEFORE_EXPANSION) {
 ERR_raise(ERR_LIB_BUF, ERR_R_PASSED_INVALID_ARGUMENT);
 return 0;
 }
 n = (len + 3) / 3 * 4;
 if ((str->flags & BUF_MEM_FLAG_SECURE))
 ret = sec_alloc_realloc(str, n);
 else
 ret = OPENSSL_clear_realloc(str->data, str->max, n);
 if (ret == NULL) {
 len = 0;
 } else {
 str->data = ret;
 str->max = n;
 memset(&str->data[str->length], 0, len - str->length);
 str->length = len;
 }
 return len;
}

void BUF_reverse(unsigned char *out, const unsigned char *in, size_t size)
{
 size_t i;
 if (in) {
 out += size - 1;
 for (i = 0; i < size; i++)
 *out-- = *in++;
 } else {
 unsigned char *q;
 char c;
 q = out + size - 1;
 for (i = 0; i < size / 2; i++) {
 c = *q;
 *q-- = *out;
 *out++ = c;
 }
 }
}