ws_symbol_export.h

   1 /*
   2  * Cross platform defines for exporting symbols from shared libraries
   3  *
   4  * $Id$
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Balint Reczey <balint@balintreczey.hu>
   8  * Copyright 2013 Balint Reczey
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version 2
  13  * of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  23  */
  24
  25 /** Reset symbol export behavior.
  26  * If you {un}define WS_BUILD_DLL on the fly you'll have to define this
  27  * as well.
  28  */
  29 #ifdef RESET_SYMBOL_EXPORT
  30
  31 #ifdef SYMBOL_EXPORT_H
  32 #undef SYMBOL_EXPORT_H
  33 #endif
  34
  35 #ifdef WS_DLL_PUBLIC
  36 #undef WS_DLL_PUBLIC
  37 #endif
  38
  39 #ifdef WS_DLL_PUBLIC_DEF
  40 #undef WS_DLL_PUBLIC_DEF
  41 #endif
  42
  43 #ifdef WS_DLL_LOCAL
  44 #undef WS_DLL_LOCAL
  45 #endif
  46
  47 #endif /* RESET_SYMBOL_EXPORT */
  48
  49 #ifndef SYMBOL_EXPORT_H
  50 #define SYMBOL_EXPORT_H
  51
  52 /* Originally copied from GCC Wiki at http://gcc.gnu.org/wiki/Visibility */
  53 #if defined _WIN32 || defined __CYGWIN__
  54   /* Compiling for Windows, so we use the Windows DLL declarations. */
  55   #ifdef WS_BUILD_DLL
  56     /*
  57      * Building a DLL; for all definitions, we want dllexport, and
  58      * (presumably so source from DLL and source from a program using the
  59      * DLL can both include a header that declares APIs and exported data
  60      * for the DLL), for declarations, either dllexport or dllimport will
  61      * work (they mean the same thing for a declaration when building a DLL).
  62      */
  63     #ifdef __GNUC__
  64       /* GCC */
  65 #define WS_DLL_PUBLIC_DEF __attribute__ ((dllexport))
  66     #else /* ! __GNUC__ */
  67       /*
  68        * Presumably MSVC.
  69        * Note: actually gcc seems to also support this syntax.
  70        */
  71 #define WS_DLL_PUBLIC_DEF __declspec(dllexport)
  72     #endif /* __GNUC__ */
  73   #else /* WS_BUILD_DLL */
  74     /*
  75      * Building a program; we should only see declarations, not definitions,
  76      * with WS_DLL_PUBLIC, and they all represent APIs or data imported
  77      * from a DLL, so use dllimport.
  78      *
  79      * For functions, export shouldn't be necessary; for data, it might
  80      * be necessary, e.g. if what's declared is an array whose size is
  81      * not given in the declaration.
  82      */
  83     #ifdef __GNUC__
  84       /* GCC */
  85 #define WS_DLL_PUBLIC_DEF __attribute__ ((dllimport))
  86     #elif ! (defined ENABLE_STATIC) /* ! __GNUC__ */
  87       /*
  88        * Presumably MSVC, and we're not building all-static.
  89        * Note: actually gcc seems to also support this syntax.
  90        */
  91 #define WS_DLL_PUBLIC_DEF __declspec(dllimport)
  92     #else /* ! __GNUC__  && ENABLE_STATIC */
  93       /*
  94        * Presumably MSVC, and we're building all-static, so we're
  95        * not building any DLLs.
  96        */
  97 #define WS_DLL_PUBLIC_DEF
  98     #endif /* __GNUC__ */
  99   #endif /* WS_BUILD_DLL */
 100
 101   /*
 102    * Symbols in a DLL are *not* exported unless they're specifically
 103    * flagged as exported, so, for a non-static but non-exported
 104    * symbol, we don't have to do anything.
 105    */
 106   #define WS_DLL_LOCAL
 107 #else /* defined _WIN32 || defined __CYGWIN__ */
 108   /*
 109    * Compiling for UN*X, where the dllimport and dllexport stuff
 110    * is neither necessary nor supported; just specify the
 111    * visibility if we have a compiler that claims compatibility
 112    * with GCC 4 or later.
 113    */
 114   #if __GNUC__ >= 4
 115     /*
 116      * Symbols exported from libraries.
 117      */
 118 #define WS_DLL_PUBLIC_DEF __attribute__ ((visibility ("default")))
 119
 120     /*
 121      * Non-static symbols *not* exported from libraries.
 122      */
 123 #define WS_DLL_LOCAL  __attribute__ ((visibility ("hidden")))
 124   #else /* ! __GNUC__ >= 4 */
 125     /*
 126      * We have no way to control visibility.
 127      */
 128     #define WS_DLL_PUBLIC_DEF
 129     #define WS_DLL_LOCAL
 130   #endif /* __GNUC__ >= 4 */
 131 #endif
 132
 133 /*
 134  * You *must* use this for exported data *declarations*; if you use
 135  * WS_DLL_PUBLIC_DEF, some compilers, such as MSVC++, will complain
 136  * about array definitions with no size.
 137  *
 138  * You must *not* use this for exported data *definitions*, as that
 139  * will, for some compilers, cause warnings about items being initialized
 140  * and declared extern.
 141  *
 142  * Either can be used for exported *function* declarations and definitions.
 143  */
 144 #define WS_DLL_PUBLIC   WS_DLL_PUBLIC_DEF extern
 145
 146 #endif /* SYMBOL_EXPORT_H */