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#ifndef __EVIL_DLFCN_H__
#define __EVIL_DLFCN_H__


#include <limits.h>


/**
 * @file evil_dlfcn.h
 * @brief The file that provides functions to manage dynamic-link libraries
 * @defgroup Evil_Dlfcn Functions that manage dynamic-link libraries.
 * @ingroup Evil
 *
x * This header provides functions to load and unload dynamic-link
 * libaries, to get the address of a symbol, and to get diagnostic
 * information.
 */


/**
 * @def RTLD_LAZY
 * Lazy function call binding.
 */
# define RTLD_LAZY    0x00001  /* lazy function call binding. Unused */

/**
 * @def RTLD_NOW
 * Immediate function call binding.
 */
# define RTLD_NOW     0x00002  /* immediate function call binding. Unused */

/**
 * @def RTLD_GLOBAL
 * Symbols in this dlopen'ed obj are visible to other dlopen'ed objs.
 */
# define RTLD_GLOBAL  0x00004  /* symbols in this dlopen'ed obj are visible
			          to other dlopen'ed objs. Unused */

/**
 * @def RTLD_LOCAL
 * Symbols in this dlopen'ed obj are not visible to other dlopen'ed objs.
 */
# define RTLD_LOCAL  0x00008  /* symbols in this dlopen'ed obj are not visible
			         to other dlopen'ed objs. Unused */

/**
 * @def RTLD_NODELETE
 * Symbols are not deleted when closed.
 */
#define RTLD_NODELETE 0x01000  /* do not delete object when closed.  */

#ifdef _GNU_SOURCE

/**
 * @def RTLD_DEFAULT
 * Symbols are searched in all the DLL opened by the current process.
 * This symbol is defined only when _GNU_SOURCE was defined before
 * including dlfcn.h.
 */
#define RTLD_DEFAULT ((void*)1) /* search the symbol on all the DLL of the current process */

/**
 * @typedef Dl_info
 * @brief A structure that stores infomation of a calling process.
 * This typedef is defined only when _GNU_SOURCE was defined before
 * including dlfcn.h.
 */
typedef struct Dl_info Dl_info;

/**
 * @struct Dl_info
 * @brief A structure that stores infomation of a calling process.
 * This structure is defined only when _GNU_SOURCE was defined before
 * including dlfcn.h.
 */
struct Dl_info
{
   const char *dli_fname;  /**< Filename of defining object */
   void       *dli_fbase;  /**< Load address of that object */
   const char *dli_sname;  /**< Name of nearest lower symbol */
   void       *dli_saddr;  /**< Exact value of nearest symbol */
};

#endif /* _GNU_SOURCE */

/**
 * @brief Map a specified executable module (either a .dll or .exe file)
 * into the address space of the user process.
 *
 * @param path Name of the module.
 * @param mode Unused.
 * @return A pointer that represent the module, or @c NULL on failure.
 *
 * Map a specified executable module (either a .dll or .exe file)
 * into the address space of the user process. If @p path is @c NULL,
 * then the module corresponding to the current process is returned.
 * Otherwise the module specified by @p path is loaded if it exists.
 * If not, @c NULL is returned. The directory separators can be forward
 * slash, or backward ones. Mapping a module can map other modules.
 * @p mode is unused.
 *
 * If an error occurred, an error string can be retrived with dlerror().
 *
 * According to the OS, the search order of the module can change,
 * according to the value of SafeDllSearchMode.
 *
 *  - For Windows Vista, Windows Server 2003, and Windows XP SP2:
 *    SafeDLLSearchMode is enabled by default.
 *  - For Windows XP and Windows 2000 SP4:  SafeDLLSearchMode is disabled
 *    by default.
 *
 * If SafeDllSearchMode is enabled
 *  - The directory from which the application loaded.
 *  - The system directory. Use the GetSystemDirectory() function
 *    to get the path of this directory.
 *  - The 16-bit system directory. There is no function that obtains
 *    the path of this directory, but it is searched.
 *  - The Windows directory. Use the GetWindowsDirectory() function
 *    to get the path of this directory.
 *  - The current directory.
 *  - The directories that are listed in the PATH environment variable.
 *    Note that this does not include the per-application path specified
 *    by the App Paths registry key.
 *
 * If SafeDllSearchMode is disabled
 *  - The directory from which the application loaded.
 *  - The current directory.
 *  - The system directory. Use the GetSystemDirectory() function
 *    to get the path of this directory.
 *  - The 16-bit system directory. There is no function that obtains
 *    the path of this directory, but it is searched.
 *  - The Windows directory. Use the GetWindowsDirectory() function
 *    to get the path of this directory.
 *  - The directories that are listed in the PATH environment variable.
 *    Note that this does not include the per-application path specified
 *    by the App Paths registry key.
 *
 * Conformity: None.
 *
 * Supported OS: Windows Vista, Windows XP or Windows 2000
 * Professional.
 *
 * @ingroup Evil_Dlfcn
 */
EAPI void *dlopen(const char* path, int mode);

/**
 * @brief Close a dynamic-link library.
 *
 * @param handle Handle that references a dynamic-link library.
 * @return O on sucess, -1 otherwise.
 *
 * Release a reference to the dynamic-link library referenced
 * by @p handle.  If the reference count drops to 0, the handle is
 * removed from the address space and is rendered invalid. @p handle
 * is the value returned by a previous call to dlopen().
 *
 * If no error occurred, the returned value is 0, otherwise the
 * returned value is -1 and an error string can be retrived with
 * dlerror().
 *
 * Conformity: None.
 *
 * Supported OS: Windows Vista, Windows XP or Windows 2000
 * Professional.
 *
 * @ingroup Evil_Dlfcn
 */
EAPI int dlclose(void* handle);

/**
 * @brief Get the address of a symbol.
 *
 * @param handle Handle that references a dynamic-link library.
 * @param symbol @c NULL-terminated string.
 * @return O on sucess, NULL otherwise.
 *
 * Return the address of the code or data location specified by the
 * string @p symbol.  @p handle references a library that contains
 * the function or variable @p symbol.
 *
 * If no error occurred, the returned value is the code or data
 * location, otherwise the returned value is NULL and an error
 * string can be retrived with dlerror().
 *
 * Conformity: None.
 *
 * Supported OS: Windows Vista, Windows XP or Windows 2000
 * Professional.
 *
 * @ingroup Evil_Dlfcn
 */
EAPI void *dlsym(void* handle, const char* symbol);

#ifdef _GNU_SOURCE

/**
 * @brief Resolve module and function pointers from the given function
 * pointer address.
 *
 * @param addr A function pointer.
 * @param info Pointer to the #Dl_info to fill.
 * @return 1 on success, 0 otherwise.
 *
 * Fill @p info with the absolute name of the module which has the
 * fonction pointer @p addr, the base address of that module, the name
 * and address of the symbol. If no symbol matching @p addr could be
 * found (as in an EXE file), then dli_sname and dli_saddr are set to
 * NULL and the function returns 1. See #Dl_info for more informations.
 *
 * This function is available only when _GNU_SOURCE was defined before
 * including dlfcn.h.
 *
 * Conformity: None.
 *
 * Supported OS: Windows Vista, Windows XP.
 *
 * @ingroup Evil_Dlfcn
 */
EAPI int dladdr (const void *addr, Dl_info *info);

#endif /* _GNU_SOURCE */

/**
 * @brief Get diagnostic information
 *
 * @return A @c NULL-terminated string if an error occurred, @c NULL
 * otherwise.
 *
 * Return a @c NULL-terminated character string describing the last
 * error that occurred on this thread during a call to dlopen(),
 * dlsym(), or dlclose(). If no such error has occurred, dlerror()
 * returns a null pointer.  At each call to dlerror(), the error
 * indication is reset.  Thus in the case of two calls to dlerror(),
 * where the second call follows the first immediately, the second
 * call will always return a null pointer.
 *
 * Conformity: None.
 *
 * Supported OS: Windows Vista, Windows XP or Windows 2000
 * Professional.
 *
 * @ingroup Evil_Dlfcn
 */
EAPI char *dlerror (void);


#endif /* __EVIL_DLFCN_H__ */