xapian-core/common/setenv.h

   1 /** @file
   2  * @brief Provide setenv() with compatibility versions
   3  */
   4 /* Copyright (C) 2019 Olly Betts
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  19  */
  20
  21 #ifndef XAPIAN_INCLUDED_SETENV_H
  22 #define XAPIAN_INCLUDED_SETENV_H
  23
  24 #ifndef PACKAGE
  25 # error config.h must be included first in each C++ source file
  26 #endif
  27
  28 #include <stdlib.h>
  29
  30 #ifdef HAVE_SETENV
  31 // setenv() provided by the system.
  32 #elif defined HAVE__PUTENV_S
  33 # if !HAVE_DECL__PUTENV_S
  34 // Mingw 3.20 doesn't declare this, but it's in the Microsoft C runtime DLL.
  35 extern "C" int _putenv_s(const char*, const char*);
  36 # endif
  37
  38 // Use a lambda function to give us a block scope to use static_assert in
  39 // while still being able to return a result.
  40 # define setenv(NAME, VALUE, OVERWRITE) ([]() { \
  41     static_assert((OVERWRITE), "OVERWRITE must be non-zero constant"); \
  42     (void)(OVERWRITE); \
  43     return _putenv_s((NAME), (VALUE)) ? -1 : 0; \
  44 })()
  45
  46 #endif
  47
  48 #endif // XAPIAN_INCLUDED_SETENV_H