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Michael Lutz

Codechange: Don't use cpp_offsetof in the save/load code.

Many of the member variables that are used in save/load are inside types
that are not standard layout types. Using pointer arithmetics to determine
addresses of members inside types that are not standard layout is generally
undefined behaviour. If we'd use C++17, it is conditionally supported, which means
each compiler may or may not support it. And even then using it for individual
array elements is syntactically not supported the the standard offsetof function.

Unfortunately, the trickery employed for saving linkgraph settings causes quite some
clutter in the settings ini files.

/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/**
 * @file safeguards.h A number of safeguards to prevent using unsafe methods.
 *
 * Unsafe methods are, for example, strndup and strncpy because they may leave the
 * string without a null termination, but also strdup and strndup because they can
 * return nullptr and then all strdups would need to be guarded against that instead
 * of using the current MallocT/ReallocT/CallocT technique of just giving the user
 * an error that too much memory was used instead of spreading that code though
 * the whole code base.
 */

#ifndef SAFEGUARDS_H
#define SAFEGUARDS_H

/* Use MallocT instead. */
#define malloc    SAFEGUARD_DO_NOT_USE_THIS_METHOD

/* Use MallocT instead. */
#define calloc    SAFEGUARD_DO_NOT_USE_THIS_METHOD

/* Use ReallocT instead. */
#define realloc   SAFEGUARD_DO_NOT_USE_THIS_METHOD

/* Use stredup instead. */
#define strdup    SAFEGUARD_DO_NOT_USE_THIS_METHOD
#define strndup   SAFEGUARD_DO_NOT_USE_THIS_METHOD

/* Use strecpy instead. */
#define strcpy    SAFEGUARD_DO_NOT_USE_THIS_METHOD
#define strncpy   SAFEGUARD_DO_NOT_USE_THIS_METHOD

/* Use strecat instead. */
#define strcat    SAFEGUARD_DO_NOT_USE_THIS_METHOD
#define strncat   SAFEGUARD_DO_NOT_USE_THIS_METHOD

/* Use seprintf instead. */
#define sprintf   SAFEGUARD_DO_NOT_USE_THIS_METHOD
#define snprintf  SAFEGUARD_DO_NOT_USE_THIS_METHOD

/* Use vseprintf instead. */
#define vsprintf  SAFEGUARD_DO_NOT_USE_THIS_METHOD
#define vsnprintf SAFEGUARD_DO_NOT_USE_THIS_METHOD

/* Use fgets instead. */
#define gets      SAFEGUARD_DO_NOT_USE_THIS_METHOD

/* No clear replacement. */
#define strtok    SAFEGUARD_DO_NOT_USE_THIS_METHOD

/* Use our own templated implementation instead of a macro or function with only one type. */
#ifdef min
#undef min
#endif

/* Use our own templated implementation instead of a macro or function with only one type. */
#ifdef max
#undef max
#endif

/* Use our own templated implementation instead of a macro or function with only one type. */
#ifdef abs
#undef abs
#endif

#endif /* SAFEGUARDS_H */