/*

 * Copyright (c) 2016, Alliance for Open Media. All rights reserved.

 *

 * This source code is subject to the terms of the BSD 2 Clause License and

 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License

 * was not distributed with this source code in the LICENSE file, you can

 * obtain it at www.aomedia.org/license/software. If the Alliance for Open

 * Media Patent License 1.0 was not distributed with this source code in the

 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.

 */

#include "aom_mem.h"

#include <assert.h>

#include <stdlib.h>

#include <string.h>

#include "include/aom_mem_intrnl.h"

#include "aom/aom_integer.h"

static size_t GetAllocationPaddingSize(size_t align) {

  assert(align > 0);

  assert(align < SIZE_MAX - ADDRESS_STORAGE_SIZE);

  return align - 1 + ADDRESS_STORAGE_SIZE;

}

// Returns 0 in case of overflow of nmemb * size.

static int check_size_argument_overflow(size_t nmemb, size_t size,

                                        size_t align) {

  if (nmemb == 0) return 1;

  const size_t alloc_padding = GetAllocationPaddingSize(align);

#if defined(AOM_MAX_ALLOCABLE_MEMORY)

  assert(AOM_MAX_ALLOCABLE_MEMORY >= alloc_padding);

  assert(AOM_MAX_ALLOCABLE_MEMORY <= SIZE_MAX);

  if (size > (AOM_MAX_ALLOCABLE_MEMORY - alloc_padding) / nmemb) return 0;

#else

  if (size > (SIZE_MAX - alloc_padding) / nmemb) return 0;

#endif

  return 1;

}

static size_t *GetMallocAddressLocation(void *const mem) {

  return ((size_t *)mem) - 1;

}

static void SetActualMallocAddress(void *const mem,

                                   const void *const malloc_addr) {

  size_t *const malloc_addr_location = GetMallocAddressLocation(mem);

  *malloc_addr_location = (size_t)malloc_addr;

}

static void *GetActualMallocAddress(void *const mem) {

  const size_t *const malloc_addr_location = GetMallocAddressLocation(mem);

  return (void *)(*malloc_addr_location);

}

void *aom_memalign(size_t align, size_t size) {

  void *x = NULL;

  if (!check_size_argument_overflow(1, size, align)) return NULL;

  const size_t aligned_size = size + GetAllocationPaddingSize(align);

  void *const addr = malloc(aligned_size);

  if (addr) {

    x = aom_align_addr((unsigned char *)addr + ADDRESS_STORAGE_SIZE, align);

    SetActualMallocAddress(x, addr);

  }

  return x;

}

void *aom_malloc(size_t size) { return aom_memalign(DEFAULT_ALIGNMENT, size); }

void *aom_calloc(size_t num, size_t size) {

  if (!check_size_argument_overflow(num, size, DEFAULT_ALIGNMENT)) return NULL;

  const size_t total_size = num * size;

  void *const x = aom_malloc(total_size);

  if (x) memset(x, 0, total_size);

  return x;

}

void aom_free(void *memblk) {

  if (memblk) {

    void *addr = GetActualMallocAddress(memblk);

    free(addr);

  }

}