msvcignoreinvalidparam.h

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/* Copyright (C) 2006,2007,2008,2015,2018 Olly Betts
 *
 * This program 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; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#ifndef XAPIAN_INCLUDED_MSVCIGNOREINVALIDPARAM_H
#define XAPIAN_INCLUDED_MSVCIGNOREINVALIDPARAM_H

// __STDC_SECURE_LIB__ doesn't appear to be publicly documented, but including
// in this check appears to be a good idea.  We cribbed this test from the
// python sources - see, for example,
// https://github.com/python/cpython/commit/74c3ea0a0f6599da7dd9a502b5a66aeb9512d8c3
#if defined _MSC_VER && _MSC_VER >= 1400 && defined __STDC_SECURE_LIB__
# include <cstdlib> // For _set_invalid_parameter_handler(), etc.
# include <crtdbg.h> // For _CrtSetReportMode, etc.

static void dummy_handler(const wchar_t*,
                          const wchar_t*,
                          const wchar_t*,
                          unsigned int,
                          uintptr_t) noexcept
{
}

// Recent versions of MSVC call an "_invalid_parameter_handler" if a
// CRT function receives an invalid parameter.  However, there are cases
// where this is totally reasonable.  To avoid the application dying,
// you just need to instantiate the MSVCIgnoreInvalidParameter class in
// the scope where you want MSVC to ignore invalid parameters.
class MSVCIgnoreInvalidParameter {
    _invalid_parameter_handler old_handler;
    int old_report_mode;

  public:
    MSVCIgnoreInvalidParameter() {
        // Install a dummy handler to avoid the program dying.
        old_handler = _set_invalid_parameter_handler(dummy_handler);
        // Make sure that no dialog boxes appear.
        old_report_mode = _CrtSetReportMode(_CRT_ASSERT, 0);
    }

    ~MSVCIgnoreInvalidParameter() {
        // Restore the previous settings.
        _set_invalid_parameter_handler(old_handler);
        _CrtSetReportMode(_CRT_ASSERT, old_report_mode);
    }
};
#else
// Mingw seems to be free of this insanity, so for mingw, older MSVC versions,
// and other platforms define a dummy class to allow MSVCIgnoreInvalidParameter
// to be used unconditionally.
struct MSVCIgnoreInvalidParameter {
    // Provide an explicit constructor so this isn't a POD struct - this seems
    // to prevent GCC warning about an unused variable whenever we instantiate
    // this class.
    MSVCIgnoreInvalidParameter() { }
};
#endif

#endif