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/** @file
* IPRT - Runtime Loader Generation.
*/
/*
* Copyright (C) 2008-2023 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* 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, in version 3 of the
* License.
*
* 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 <https://www.gnu.org/licenses>.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
* in the VirtualBox distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*
* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
*/
#include <iprt/types.h>
#ifdef RT_RUNTIME_LOADER_GENERATE_BODY_STUBS
# include <iprt/ldr.h>
# include <iprt/log.h>
# include <iprt/once.h>
#endif
/** @defgroup grp_rt_runtime_loader Runtime Loader Generation
* @ingroup grp_rt
*
* How to use this loader generator
*
* This loader generator can be used to generate stub code for loading a shared
* library and its functions at runtime, or for generating a header file with
* the declaration of the loader function and optionally declarations for the
* functions loaded. It should be included in a header file or a C source
* file, after defining certain macros which it makes use of.
*
* To generate the C source code for function proxy stubs and the library
* loader function, you should define the following macros in your source file
* before including this header:
*
* RT_RUNTIME_LOADER_LIB_NAME - the file name of the library to load
* RT_RUNTIME_LOADER_FUNCTION - the name of the loader function
* RT_RUNTIME_LOADER_INSERT_SYMBOLS - a macro containing the names of the
* functions to be loaded, defined in the
* following pattern:
* @code
* #define RT_RUNTIME_LOADER_INSERT_SYMBOLS \
* RT_PROXY_STUB(func_name, ret_type, (long_param_list), (short_param_list)) \
* RT_PROXY_STUB(func_name2, ret_type2, (long_param_list2), (short_param_list2)) \
* ...
* @endcode
*
* where long_param_list is a parameter list for declaring the function of the
* form (type1 arg1, type2 arg2, ...) and short_param_list for calling it, of
* the form (arg1, arg2, ...).
*
* To generate the header file, you should define RT_RUNTIME_LOADER_FUNCTION
* and if you wish to generate declarations for the functions you should
* additionally define RT_RUNTIME_LOADER_INSERT_SYMBOLS as above and
* RT_RUNTIME_LOADER_GENERATE_DECLS (without a value) before including this
* file.
*
* @{
*/
/** @todo this is far too complicated. A script for generating the files would
* probably be preferable.
*
* bird> An alternative is to generate assembly jump wrappers, this only
* requires the symbol names and prefix. I've done this ages ago when we forked
* the EMX/GCC toolchain on OS/2... It's a wee bit more annoying in x86 PIC/PIE
* mode, but nothing that cannot be dealt with.
*/
/** @todo r=bird: The use of RTR3DECL here is an unresolved issue. */
/** @todo r=bird: The lack of RT_C_DECLS_BEGIN/END is an unresolved issue. Here
* we'll get into trouble if we use the same symbol names as the
* original! */
/** @todo r=bird: The prefix usage here is very confused: RT_RUNTIME_LOADER_XXX,
* RT_PROXY_STUB, etc. */
#ifdef RT_RUNTIME_LOADER_GENERATE_BODY_STUBS
/* The following are the symbols which we need from the library. */
# define RT_PROXY_STUB(function, rettype, signature, shortsig) \
void (*function ## _fn)(void); \
RTR3DECL(rettype) function signature \
{ return ( (rettype (*) signature) function ## _fn ) shortsig; }
RT_RUNTIME_LOADER_INSERT_SYMBOLS
# undef RT_PROXY_STUB
/* Now comes a table of functions to be loaded from the library. */
typedef struct
{
const char *pszName;
void (**ppfn)(void);
} RTLDRSHAREDFUNC;
# define RT_PROXY_STUB(s, dummy1, dummy2, dummy3 ) { #s , & s ## _fn } ,
static RTLDRSHAREDFUNC g_aSharedFuncs[] =
{
RT_RUNTIME_LOADER_INSERT_SYMBOLS
{ NULL, NULL }
};
# undef RT_PROXY_STUB
/**
* The function which does the actual work for RT_RUNTIME_LOADER_FUNCTION,
* serialised for thread safety.
*/
static DECLCALLBACK(int) rtldrLoadOnce(void *)
{
RTLDRMOD hLib;
int rc;
LogFlowFunc(("\n"));
rc = RTLdrLoadEx(RT_RUNTIME_LOADER_LIB_NAME, &hLib, RTLDRLOAD_FLAGS_LOCAL | RTLDRLOAD_FLAGS_NO_UNLOAD, NULL);
for (unsigned i = 0; RT_SUCCESS(rc) && g_aSharedFuncs[i].pszName != NULL; ++i)
rc = RTLdrGetSymbol(hLib, g_aSharedFuncs[i].pszName, (void **)g_aSharedFuncs[i].ppfn);
LogFlowFunc(("rc = %Rrc\n", rc));
return rc;
}
/**
* Load the shared library RT_RUNTIME_LOADER_LIB_NAME and resolve the symbols
* pointed to by RT_RUNTIME_LOADER_INSERT_SYMBOLS.
*
* May safely be called from multiple threads and will not return until the
* library is loaded or has failed to load.
*
* @returns IPRT status code.
*/
RTR3DECL(int) RT_RUNTIME_LOADER_FUNCTION(void)
{
static RTONCE s_Once = RTONCE_INITIALIZER;
int rc;
LogFlowFunc(("\n"));
rc = RTOnce(&s_Once, rtldrLoadOnce, NULL);
LogFlowFunc(("rc = %Rrc\n", rc));
return rc;
}
#elif defined(RT_RUNTIME_LOADER_GENERATE_HEADER)
# ifdef RT_RUNTIME_LOADER_GENERATE_DECLS
/* Declarations of the functions that we need from
* RT_RUNTIME_LOADER_LIB_NAME */
# define RT_PROXY_STUB(function, rettype, signature, shortsig) \
RTR3DECL(rettype) function signature ;
RT_RUNTIME_LOADER_INSERT_SYMBOLS
# undef RT_PROXY_STUB
# endif /* RT_RUNTIME_LOADER_GENERATE_DECLS */
/**
* Try to dynamically load the library. This function should be called before
* attempting to use any of the library functions. It is safe to call this
* function multiple times.
*
* @returns iprt status code
*/
RTR3DECL(int) RT_RUNTIME_LOADER_FUNCTION(void);
#else
# error "One of RT_RUNTIME_LOADER_GENERATE_HEADER or RT_RUNTIME_LOADER_GENERATE_BODY_STUBS must be defined when including this file"
#endif
/** @} */
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