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/* Copyright (c) 2008 The Android Open Source Project
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/*
* Lazy Dynamic Linking Support
*
* This header file is meant to be included multiple times.
*
* It is used to define function pointers to symbols in external
* shared objects (Unix dynamic libraries) which will be lazily resolved
* at runtime, by calling a specific initialization function.
*
* You must define, before including this header, a DYNLINK_FUNCTIONS
* macro which must contain a sequence of DYNLINK_FUNC(ret,name,sig)
* statements.
*
* In each statement, 'ret' is a function return type, 'name' is
* the function's name as provided by the library, and 'sig' is
* the function signature, including enclosing parentheses.
*
* Here's an example:
*
* #define DYNLINK_FUNCTIONS \
* DYNLINK_FUNC(int,open,(const char*, int)) \
* DYNLINK_FUNC(int,read,(int,char*,int)) \
* DYNLINK_FUNC(int,close,(int)) \
*
*
* You must also define a DYNLINK_FUNCTIONS_INIT macro which contains the
* name of a generated function used to initialize the function pointers.
* (see below)
*/
#ifndef DYNLINK_FUNCTIONS
#error DYNLINK_FUNCTIONS should be defined when including this file
#endif
#ifndef DYNLINK_FUNCTIONS_INIT
#error DYNLINK_FUNCTIONS_INIT should be defined when including this file
#endif
/* just in case */
#undef DYNLINK_FUNC
/* define pointers to dynamic library functions as static pointers.
*/
#define DYNLINK_FUNC(ret,name,sig) \
static ret (*_dynlink_##name) sig ;
DYNLINK_FUNCTIONS
#undef DYNLINK_FUNC
/* now define a function that tries to load all dynlink function
* pointers. returns 0 on success, or -1 on error (i.e. if any of
* the functions could not be loaded).
*
* 'library' must be the result of a succesful dlopen() call
*
* You must define DYNLINK_FUNCTIONS_INIT
*/
static int
DYNLINK_FUNCTIONS_INIT(void* library)
{
#define DYNLINK_FUNC(ret,name,sig) \
do { \
_dynlink_##name = dlsym( library, STRINGIFY(name) ); \
if (_dynlink_##name == NULL) goto Fail; \
} while (0);
DYNLINK_FUNCTIONS
#undef DYNLINK_FUNC
return 0;
Fail:
return -1;
}
/* in user code, use FF(function_name) to invoke the
* corresponding dynamic function named 'function_name'
* after initialization succeeded.
*/
#ifndef FF
#define FF(name) (*_dynlink_##name)
#endif
/* clear macros */
#undef DYNLINK_FUNC
#undef DYNLINK_FUNCTIONS
#undef DYNLINK_FUNCTIONS_INIT
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