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// Copyright (c) 2011 The Chromium Authors. All rights reserved.

// Use of this source code is governed by a BSD-style license that can be

// found in the LICENSE file.

#ifndef BASE_DEBUG_ALIAS_H_

#define BASE_DEBUG_ALIAS_H_

#include "base/base_export.h"

#include "base/stl_util.h"

#include "base/strings/string_util.h"

namespace base {

namespace debug {

// Make the optimizer think that var is aliased. This is to prevent it from

// optimizing out local variables that would not otherwise be live at the point

// of a potential crash.

// base::debug::Alias should only be used for local variables, not globals,

// object members, or function return values - these must be copied to locals if

// you want to ensure they are recorded in crash dumps.

// Note that if the local variable is a pointer then its value will be retained

// but the memory that it points to will probably not be saved in the crash

// dump - by default only stack memory is saved. Therefore the aliasing

// technique is usually only worthwhile with non-pointer variables. If you have

// a pointer to an object and you want to retain the object's state you need to

// copy the object or its fields to local variables. Example usage:

//   int last_error = err_;

//   base::debug::Alias(&last_error);

//   DEBUG_ALIAS_FOR_CSTR(name_copy, p->name, 16);

//   CHECK(false);

void BASE_EXPORT Alias(const void* var);

}  // namespace debug

}  // namespace base

// Convenience macro that copies the null-terminated string from |c_str| into a

// stack-allocated char array named |var_name| that holds up to |char_count|

// characters and should be preserved in memory dumps.

#define DEBUG_ALIAS_FOR_CSTR(var_name, c_str, char_count)   \

  char var_name[char_count];                                \

  ::base::strlcpy(var_name, (c_str), base::size(var_name)); \

  ::base::debug::Alias(var_name);

#endif  // BASE_DEBUG_ALIAS_H_