// Copyright 2018 The Fuchsia Authors
//
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT

#include "object/buffer_chain.h"

// Makes a const void* look like a user_in_ptr<const void>.
//
// Sometimes we need to copy data from kernel space. KernelPtrAdapter allows us to implement the
// copy logic once for both const void* and user_in_ptr<const void>.
class KernelPtrAdapter {
 public:
  explicit KernelPtrAdapter(const void* p) : p_(p) {}
  zx_status_t copy_array_from_user(void* dst, size_t count) const {
    memcpy(dst, p_, count);
    return ZX_OK;
  }
  KernelPtrAdapter byte_offset(size_t offset) const {
    return KernelPtrAdapter(reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(p_) + offset));
  }

 private:
  const void* p_;
};

zx_status_t BufferChain::CopyInKernel(const void* src, size_t dst_offset, size_t size) {
  return CopyInCommon(KernelPtrAdapter(src), dst_offset, size);
}

template zx_status_t BufferChain::CopyInCommon(user_in_ptr<const void> src, size_t dst_offset,
                                               size_t size);