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/*
Copyright (C) 2010 Andreas Baumann <abaumann@yahoo.com>
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 3 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, see <http://www.gnu.org/licenses/>.
*/
#ifndef WOLF_LOADER_H
#define WOLF_LOADER_H
/**
* @addtogroup wolf_library Loadable library support
* @{
*/
/**
* @file loader.h
* @brief Portable library loading functions
* @author Andreas Baumann <abaumann@yahoo.com>
*/
#ifdef __cplusplus
extern "C" {
#endif
#include "port/sys.h"
#include "errors.h"
#include <stddef.h> /* for size_t */
#if defined _WIN32
#define WIN32_MEAN_AND_LEAN
#include <windows.h>
#endif
/* @brief handle representing a shared library
*/
typedef struct wolf_library_t *wolf_library_p;
/* @brief returned by wolf_library_get_func, cast it to the custom function pointer */
#ifdef _WIN32
#define WOLF_LIBRARY_FUNCPTR FARPROC
#else
#define WOLF_LIBRARY_FUNCPTR void *
#endif
/* @brief casts a library symbol to a function pointer of a given type.
*
* Reason: conversion from void * to function pointer is illegal by ISO-99
* (though it works actually on Posix)
*
* for the reasons why naive casting doesn't work with dlsym, see:
*
* http://en.wikipedia.org/wiki/Dynamic_loading
*/
#if defined _WIN32
#define WOLF_LIBRARY_FUNC_CAST( symbol__, func_t__, func__ ) func__ = (func_t__)symbol__
#else
#define WOLF_LIBRARY_FUNC_CAST( symbol__, func_t__, func__ ) \
{ \
union { func_t__ f__; void *s__; } alias__; \
alias__.s__ = symbol__; \
func__ = alias__.f__; \
}
#endif
/**
* Loads a shared library.
*
* @param error indicates errors while loading the library
*
* @return the libary object
*/
wolf_library_p wolf_library_load( const char *name, wolf_error_t *error );
/**
* Free up resources used by the library object.
*
* @param library the library object to free
*
* @return WOLF_OK if library has been unloaded,
* WOLF_ERR_INTERNAL_STATE if the library handle is in an illegal state
* (like double freeing the same library)
*/
wolf_error_t wolf_library_unload( wolf_library_p library );
/**
* Converts the last error and state of the library object in a human readable message.
*
* @param error the error which happened after calling a library loader function
* @param library the library object for which we want a error message
* @param buf the buffer which will hold the error message
* @param buflen the size of the buffer
*
* @return a pointer to buf for convenience
*/
char *wolf_library_errmsg( const wolf_error_t error, const wolf_library_p library, char *buf, size_t buflen );
/**
* Gets a symbol (a function) from the library object. It has to be
* casted properly to the function you are expecting to call.
*
* @param library the library object
* @param name name of the symbol to retrieve
* @param error WOLF_OK if the symbol could be loaded
*
* @return a pointer to the retrieved symbol
*/
WOLF_LIBRARY_FUNCPTR wolf_library_get_func( const wolf_library_p library, const char *name, wolf_error_t *error );
/** @} */ /* @addtogroup wolf_library */
#endif /* ifndef WOLF_LOADER_H */
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