core/fxcrt/fx_memory_pa.cpp

// Copyright 2022 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com

#include "core/fxcrt/fx_memory.h"

#include "core/fxcrt/compiler_specific.h"
#include "core/fxcrt/fx_safe_types.h"

#if defined(PDF_USE_PARTITION_ALLOC)
#include "partition_alloc/partition_alloc.h"
#else
#error "File compiled under wrong build option."
#endif

namespace {

constexpr partition_alloc::PartitionOptions kOptions = {};

partition_alloc::PartitionAllocator& GetGeneralPartitionAllocator() {
  static auto* general_allocator =
      new partition_alloc::PartitionAllocator{kOptions};
  return *general_allocator;
}

partition_alloc::PartitionAllocator& GetStringPartitionAllocator() {
  static auto* string_allocator =
      new partition_alloc::PartitionAllocator{kOptions};
  return *string_allocator;
}

}  // namespace

namespace pdfium::internal {

void* Alloc(size_t num_members, size_t member_size) {
  FX_SAFE_SIZE_T total = member_size;
  total *= num_members;
  if (!total.IsValid()) {
    return nullptr;
  }

  return GetGeneralPartitionAllocator()
      .root()
      ->AllocInline<partition_alloc::AllocFlags::kReturnNull>(
          total.ValueOrDie(), "GeneralPartition");
}

void* Calloc(size_t num_members, size_t member_size) {
  FX_SAFE_SIZE_T total = member_size;
  total *= num_members;
  if (!total.IsValid()) {
    return nullptr;
  }

  return GetGeneralPartitionAllocator()
      .root()
      ->AllocInline<partition_alloc::AllocFlags::kReturnNull |
                    partition_alloc::AllocFlags::kZeroFill>(total.ValueOrDie(),
                                                            "GeneralPartition");
}

void* Realloc(void* ptr, size_t num_members, size_t member_size) {
  FX_SAFE_SIZE_T size = num_members;
  size *= member_size;
  if (!size.IsValid()) {
    return nullptr;
  }

  return GetGeneralPartitionAllocator()
      .root()
      ->Realloc<partition_alloc::AllocFlags::kReturnNull>(
          ptr, size.ValueOrDie(), "GeneralPartition");
}

void Dealloc(void* ptr) {
  // TODO(palmer): Removing this check exposes crashes when PDFium callers
  // attempt to free |nullptr|. Although libc's |free| allows freeing |NULL|, no
  // other Partition Alloc callers need this tolerant behavior. Additionally,
  // checking for |nullptr| adds a branch to |PartitionFree|, and it's nice to
  // not have to have that.
  //
  // So this check is hiding (what I consider to be) bugs, and we should try to
  // fix them. https://bugs.chromium.org/p/pdfium/issues/detail?id=690
  if (ptr) {
    GetGeneralPartitionAllocator().root()->Free(ptr);
  }
}

void* StringAlloc(size_t num_members, size_t member_size) {
  FX_SAFE_SIZE_T total = member_size;
  total *= num_members;
  if (!total.IsValid()) {
    return nullptr;
  }

  return GetStringPartitionAllocator()
      .root()
      ->AllocInline<partition_alloc::AllocFlags::kReturnNull>(
          total.ValueOrDie(), "StringPartition");
}

void StringDealloc(void* ptr) {
  GetStringPartitionAllocator().root()->Free(ptr);
}

}  // namespace pdfium::internal