libs/ldap/include/ldap_cdefs.h

   1 /* $OpenLDAP$ */
   2 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
   3  *
   4  * Copyright 1998-2022 The OpenLDAP Foundation.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted only as authorized by the OpenLDAP
   9  * Public License.
  10  *
  11  * A copy of this license is available in file LICENSE in the
  12  * top-level directory of the distribution or, alternatively, at
  13  * <http://www.OpenLDAP.org/license.html>.
  14  */
  15 /* LDAP C Defines */
  16
  17 #ifndef _LDAP_CDEFS_H
  18 #define _LDAP_CDEFS_H
  19
  20 #if defined(__cplusplus) || defined(c_plusplus)
  21 #       define LDAP_BEGIN_DECL  extern "C" {
  22 #       define LDAP_END_DECL    }
  23 #else
  24 #       define LDAP_BEGIN_DECL  /* begin declarations */
  25 #       define LDAP_END_DECL    /* end declarations */
  26 #endif
  27
  28 #if !defined(LDAP_NO_PROTOTYPES) && ( defined(LDAP_NEEDS_PROTOTYPES) || \
  29         defined(__STDC__) || defined(__cplusplus) || defined(c_plusplus) )
  30
  31         /* ANSI C or C++ */
  32 #       define LDAP_P(protos)   protos
  33 #       define LDAP_CONCAT1(x,y)        x ## y
  34 #       define LDAP_CONCAT(x,y) LDAP_CONCAT1(x,y)
  35 #       define LDAP_STRING(x)   #x /* stringify without expanding x */
  36 #       define LDAP_XSTRING(x)  LDAP_STRING(x) /* expand x, then stringify */
  37
  38 #ifndef LDAP_CONST
  39 #       define LDAP_CONST       const
  40 #endif
  41
  42 #else /* no prototypes */
  43
  44         /* traditional C */
  45 #       define LDAP_P(protos)   ()
  46 #       define LDAP_CONCAT(x,y) x/**/y
  47 #       define LDAP_STRING(x)   "x"
  48
  49 #ifndef LDAP_CONST
  50 #       define LDAP_CONST       /* no const */
  51 #endif
  52
  53 #endif /* no prototypes */
  54
  55 #if (__GNUC__) * 1000 + (__GNUC_MINOR__) >= 2006
  56 #       define LDAP_GCCATTR(attrs)      __attribute__(attrs)
  57 #else
  58 #       define LDAP_GCCATTR(attrs)
  59 #endif
  60
  61 /*
  62  * Support for Windows DLLs.
  63  *
  64  * When external source code includes header files for dynamic libraries,
  65  * the external source code is "importing" DLL symbols into its resulting
  66  * object code. On Windows, symbols imported from DLLs must be explicitly
  67  * indicated in header files with the __declspec(dllimport) directive.
  68  * This is not totally necessary for functions because the compiler
  69  * (gcc or MSVC) will generate stubs when this directive is absent.
  70  * However, this is required for imported variables.
  71  *
  72  * The LDAP libraries, i.e. liblber and libldap, can be built as
  73  * static or shared, based on configuration. Just about all other source
  74  * code in OpenLDAP use these libraries. If the LDAP libraries
  75  * are configured as shared, 'configure' defines the LDAP_LIBS_DYNAMIC
  76  * macro. When other source files include LDAP library headers, the
  77  * LDAP library symbols will automatically be marked as imported. When
  78  * the actual LDAP libraries are being built, the symbols will not
  79  * be marked as imported because the LBER_LIBRARY or LDAP_LIBRARY macros
  80  * will be respectively defined.
  81  *
  82  * Any project outside of OpenLDAP with source code wanting to use
  83  * LDAP dynamic libraries should explicitly define LDAP_LIBS_DYNAMIC.
  84  * This will ensure that external source code appropriately marks symbols
  85  * that will be imported.
  86  *
  87  * The slapd executable, itself, can be used as a dynamic library.
  88  * For example, if a backend module is compiled as shared, it will
  89  * import symbols from slapd. When this happens, the slapd symbols
  90  * must be marked as imported in header files that the backend module
  91  * includes. Remember that slapd links with various static libraries.
  92  * If the LDAP libraries were configured as static, their object
  93  * code is also part of the monolithic slapd executable. Thus, when
  94  * a backend module imports symbols from slapd, it imports symbols from
  95  * all of the static libraries in slapd as well. Thus, the SLAP_IMPORT
  96  * macro, when defined, will appropriately mark symbols as imported.
  97  * This macro should be used by shared backend modules as well as any
  98  * other external source code that imports symbols from the slapd
  99  * executable as if it were a DLL.
 100  *
 101  * Note that we don't actually have to worry about using the
 102  * __declspec(dllexport) directive anywhere. This is because both
 103  * MSVC and Mingw provide alternate (more effective) methods for exporting
 104  * symbols out of binaries, i.e. the use of a DEF file.
 105  *
 106  * NOTE ABOUT BACKENDS: Backends can be configured as static or dynamic.
 107  * When a backend is configured as dynamic, slapd will load the backend
 108  * explicitly and populate function pointer structures by calling
 109  * the backend's well-known initialization function. Because of this
 110  * procedure, slapd never implicitly imports symbols from dynamic backends.
 111  * This makes it unnecessary to tag various backend functions with the
 112  * __declspec(dllimport) directive. This is because neither slapd nor
 113  * any other external binary should ever be implicitly loading a backend
 114  * dynamic module.
 115  *
 116  * Backends are supposed to be self-contained. However, it appears that
 117  * back-meta DOES implicitly import symbols from back-ldap. This means
 118  * that the __declspec(dllimport) directive should be marked on back-ldap
 119  * functions (in its header files) if and only if we're compiling for
 120  * windows AND back-ldap has been configured as dynamic AND back-meta
 121  * is the client of back-ldap. When client is slapd, there is no effect
 122  * since slapd does not implicitly import symbols.
 123  *
 124  * TODO(?): Currently, back-meta nor back-ldap is supported for Mingw32.
 125  * Thus, there's no need to worry about this right now. This is something that
 126  * may or may not have to be addressed in the future.
 127  */
 128
 129 /* LBER library */
 130 #if defined(_WIN32) && \
 131     ((defined(LDAP_LIBS_DYNAMIC) && !defined(LBER_LIBRARY)) || \
 132      (!defined(LDAP_LIBS_DYNAMIC) && defined(SLAPD_IMPORT)))
 133 #       define LBER_F(type)             extern __declspec(dllimport) type
 134 #       define LBER_V(type)             extern __declspec(dllimport) type
 135 #else
 136 #       define LBER_F(type)             extern type
 137 #       define LBER_V(type)             extern type
 138 #endif
 139
 140 /* LDAP library */
 141 #if defined(_WIN32) && \
 142     ((defined(LDAP_LIBS_DYNAMIC) && !defined(LDAP_LIBRARY)) || \
 143      (!defined(LDAP_LIBS_DYNAMIC) && defined(SLAPD_IMPORT)))
 144 #       define LDAP_F(type)             extern __declspec(dllimport) type
 145 #       define LDAP_V(type)             extern __declspec(dllimport) type
 146 #else
 147 #       define LDAP_F(type)             extern type
 148 #       define LDAP_V(type)             extern type
 149 #endif
 150
 151 /* AVL library */
 152 #if defined(_WIN32) && defined(SLAPD_IMPORT)
 153 #       define LDAP_AVL_F(type)         extern __declspec(dllimport) type
 154 #       define LDAP_AVL_V(type)         extern __declspec(dllimport) type
 155 #else
 156 #       define LDAP_AVL_F(type)         extern type
 157 #       define LDAP_AVL_V(type)         extern type
 158 #endif
 159
 160 /* LDIF library */
 161 #if defined(_WIN32) && defined(SLAPD_IMPORT)
 162 #       define LDAP_LDIF_F(type)        extern __declspec(dllimport) type
 163 #       define LDAP_LDIF_V(type)        extern __declspec(dllimport) type
 164 #else
 165 #       define LDAP_LDIF_F(type)        extern type
 166 #       define LDAP_LDIF_V(type)        extern type
 167 #endif
 168
 169 /* LUNICODE library */
 170 #if defined(_WIN32) && defined(SLAPD_IMPORT)
 171 #       define LDAP_LUNICODE_F(type)    extern __declspec(dllimport) type
 172 #       define LDAP_LUNICODE_V(type)    extern __declspec(dllimport) type
 173 #else
 174 #       define LDAP_LUNICODE_F(type)    extern type
 175 #       define LDAP_LUNICODE_V(type)    extern type
 176 #endif
 177
 178 /* LUTIL library */
 179 #if defined(_WIN32) && defined(SLAPD_IMPORT)
 180 #       define LDAP_LUTIL_F(type)       extern __declspec(dllimport) type
 181 #       define LDAP_LUTIL_V(type)       extern __declspec(dllimport) type
 182 #else
 183 #       define LDAP_LUTIL_F(type)       extern type
 184 #       define LDAP_LUTIL_V(type)       extern type
 185 #endif
 186
 187 /* REWRITE library */
 188 #if defined(_WIN32) && defined(SLAPD_IMPORT)
 189 #       define LDAP_REWRITE_F(type)     extern __declspec(dllimport) type
 190 #       define LDAP_REWRITE_V(type)     extern __declspec(dllimport) type
 191 #else
 192 #       define LDAP_REWRITE_F(type)     extern type
 193 #       define LDAP_REWRITE_V(type)     extern type
 194 #endif
 195
 196 /* SLAPD (as a dynamic library exporting symbols) */
 197 #if defined(_WIN32) && defined(SLAPD_IMPORT)
 198 #       define LDAP_SLAPD_F(type)       extern __declspec(dllimport) type
 199 #       define LDAP_SLAPD_V(type)       extern __declspec(dllimport) type
 200 #else
 201 #       define LDAP_SLAPD_F(type)       extern type
 202 #       define LDAP_SLAPD_V(type)       extern type
 203 #endif
 204
 205 /* SLAPD (as a dynamic library exporting symbols) */
 206 #if defined(_WIN32) && defined(SLAPD_IMPORT)
 207 #       define LDAP_SLAPI_F(type)       extern __declspec(dllimport) type
 208 #       define LDAP_SLAPI_V(type)       extern __declspec(dllimport) type
 209 #else
 210 #       define LDAP_SLAPI_F(type)       extern type
 211 #       define LDAP_SLAPI_V(type)       extern type
 212 #endif
 213
 214 /* SLAPD (as a dynamic library exporting symbols) */
 215 #if defined(_WIN32) && defined(SLAPD_IMPORT)
 216 #       define SLAPI_F(type)            extern __declspec(dllimport) type
 217 #       define SLAPI_V(type)            extern __declspec(dllimport) type
 218 #else
 219 #       define SLAPI_F(type)            extern type
 220 #       define SLAPI_V(type)            extern type
 221 #endif
 222
 223 /*
 224  * C library. Mingw32 links with the dynamic C run-time library by default,
 225  * so the explicit definition of CSTATIC will keep dllimport from
 226  * being defined, if desired.
 227  *
 228  * MSVC defines the _DLL macro when the compiler is invoked with /MD or /MDd,
 229  * which means the resulting object code will be linked with the dynamic
 230  * C run-time library.
 231  *
 232  * Technically, it shouldn't be necessary to redefine any functions that
 233  * the headers for the C library should already contain. Nevertheless, this
 234  * is here as a safe-guard.
 235  *
 236  * TODO: Determine if these macros ever get expanded for Windows. If not,
 237  * the declspec expansion can probably be removed.
 238  */
 239 #if (defined(__MINGW32__) && !defined(CSTATIC)) || \
 240     (defined(_MSC_VER) && defined(_DLL))
 241 #       define LDAP_LIBC_F(type)        extern __declspec(dllimport) type
 242 #       define LDAP_LIBC_V(type)        extern __declspec(dllimport) type
 243 #else
 244 #       define LDAP_LIBC_F(type)        extern type
 245 #       define LDAP_LIBC_V(type)        extern type
 246 #endif
 247
 248 #endif /* _LDAP_CDEFS_H */