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finished and documented

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Marc Wäckerlin 20 years ago
parent 15cece6028
commit ad44ffdf1b
1 changed files with 216 additions and 60 deletions
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  1. 276
      mrw/dynamiclibrary.hpp

276
mrw/dynamiclibrary.hpp
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@ -9,6 +9,9 @@
@license LGPL, see file <a href="license.html">COPYING</a>
$Log$
Revision 1.2 2005/02/21 16:16:47 marc
finished and documented
Revision 1.1 2005/02/18 15:53:56 marc
initial release
@ -27,8 +30,46 @@
namespace mrw {
/** @defgroup dll Dynamic Library Loading (ltdl)
Implements a C++ wrapper around the Libtool's
platform independent dynamic library loading library named
libltdl. See <code>info&nbsp;libtool</code> for more
information.
Loading a symbol from a shared library:
@code
void fn() throw(mrw::DynamicLibrary::failure) {
static DynamicLibrary lib("libsomething");
static void(*theRealFunction)() =
(void(*)())lib.symbol("theRealFunction");
(*theRealFunction)(); // call the loaded function
}
@endcode
@pre #include <mrw/dynamiclibrary.hpp>
@pre Files that use this wrapper must be linked with libltdl,
with GNU g++ on UNIX, this is link option: @c -lltdl
*/
//@{
//============================================================================
/** @brief Dynamic Library loaded from the filesystem at runtime.
This class is responsible for loading dynamic&nbsp;/ shared
libraries from the filesystem and extract symbols, means
functions to assign them to function pointers that can then be
accessed.
@copydoc dll
*/
class DynamicLibrary {
//............................................................... typedefs
public:
/// failure in access to shared libraries
class failure: public mrw::runtime_error {
public:
failure(const std::string& arg) throw(std::bad_exception):
@ -37,45 +78,32 @@ namespace mrw {
+mrw::ifelse(lt_dlerror(), "<none>")) {
}
};
class Lib {
Lib() throw(): _lib(0) {}
Lib(const std::string& lib) throw(std::exception): _lib(0) {
open(lib);
}
~Lib() throw() {
try {close();} catch(...) {}
}
operator bool() throw() {
return _lib;
}
Lib& open(const std::string& lib) throw(std::exception) {
close();
if (!(_lib = lt_dlopenext(lib.c_str())))
throw failure("cannot open dynamic library "+lib);
return *this;
}
Lib& close() throw(std::exception) {
if (_lib && lt_dlclose(_lib)!=0)
throw failure("cannot close dynamic library");
_lib = 0;
return *this;
}
private:
friend class DynamicLibrary;
lt_dlhandle handle() throw(std::exception) {
if (!_lib)
throw failure("library not open");
return _lib;
}
private:
lt_dlhandle _lib;
};
//................................................................ methods
public:
/** @brief initialize, but open dynamic library later
@throw failure if initialisation fails
*/
DynamicLibrary() throw(std::exception): _opened(false) {
if (lt_dlinit()>0)
throw failure("cannot initialize dynamic library loader");
_opened = true;
}
/** @brief load a dynamic library from a file
It is not necessary to specify the extension, the system
dependant shared object&nbsp;/ dynamic library extension is
automatically added. Also, if no path is given, the library
is automatically looked for in your system's library
paths. You can also specify additional paths to look in,
e.g. with addSearchDir.
@param lib the name of the library without the extension
@throw failure if initialisation fails
@throw failure if opeing the library fails
*/
DynamicLibrary(const std::string& lib) throw(std::exception):
_opened(false) {
if (lt_dlinit()>0)
@ -83,84 +111,212 @@ namespace mrw {
_opened = true;
_lib.open(lib);
}
/// close and clean up
~DynamicLibrary() throw() {
try {close();} catch (...) {}
if (_opened) lt_dlexit();
}
/** @brief load a dynamic library from a file
It is not necessary to specify the extension, the system
dependant shared object&nbsp;/ dynamic library extension is
automatically added. Also, if no path is given, the library
is automatically looked for in your system's library
paths. You can also specify additional paths to look in,
e.g. with addSearchDir.
@param lib the name of the library without the extension
@throw failure if opeing the library fails
*/
DynamicLibrary& open(const std::string& lib) throw(std::exception) {
_lib.open(lib);
return *this;
}
/** @brief close the dynamic library
@throw failure if the library was open and close failed
*/
DynamicLibrary& close() throw(std::exception) {
_lib.close();
if (!isResident()) _lib.close();
return *this;
}
/** @brief make the library resident
Makes the library resident, so that it cannot be
closed. This can be useful if a module implements some core
functionality in your project, which would cause your code
to crash if removed.
@throw failure in case of an error
*/
DynamicLibrary& resident() throw(std::exception) {
if (lt_dlmakeresident(_lib.handle())!=0)
throw failure("cannot make library resident");
return *this;
}
/** @brief check whether the library is resident
@throw failure if the library is not open */
bool isResident() throw(std::exception) {
return lt_dlisresident(_lib.handle())==1;
}
/** @brief load a symbol from the library
@warning The symbol is returned as void* and must be
converted to the correct function pointer. If this
conversion is wrong, then your process will crash, or even
worse, behave in an unexpected way, so be careful!
*/
lt_ptr symbol(const std::string& name) throw(std::exception) {
lt_ptr sym(lt_dlsym(_lib.handle(), name.c_str()));
if (!sym)
throw failure("cannot load dynamic library symbol: "+name);
return sym;
}
/**
{{"name1", &name1}, {"name2", &name2}, 0}
/** register a list of preloaded modules
@code
const lt_dlsymlist symbols[] = {
{"symbol1", &fnptr1}, {"symbol2", &fnptr2}, 0
}
lib.preload(symbols);
@endcode
@param symbols a null terminated C array of structs of name
character pointer and function pointer
@note if symbols is @c 0, all previousely registered
symbols except the list set by preloadDefault are deleted
*/
DynamicLibrary& preload(const lt_dlsymlist* symbols)
DynamicLibrary& preload(const lt_dlsymlist symbols[])
throw(std::exception) {
if (lt_dlpreload(symbols)!=0)
throw failure("error in preloading libraries");
return *this;
}
/**
{{"name1", &name1}, {"name2", &name2}, 0}
/** register the default list of preloaded modules
@code
const lt_dlsymlist symbols[] = {
{"symbol1", &fnptr1}, {"symbol2", &fnptr2}, 0
}
lib.preloadDefault(symbols);
@endcode
@param symbols a null terminated C array of structs of name
character pointer and function pointer
*/
DynamicLibrary& preloadDefault(const lt_dlsymlist* symbols)
static void preloadDefault(const lt_dlsymlist symbols[])
throw(std::exception) {
if (lt_dlpreload_default(symbols)!=0)
throw failure("error in preloading libraries");
return *this;
}
int foreachfile(const char* searchPath,
int(*function)(const char*, lt_ptr),
lt_ptr data) throw() {
return lt_dlforeachfile(searchPath, function, data);
/** @brief set the default list of preloaded symbols */
static void preloadedSymbols() throw(std::bad_exception) {
LTDL_SET_PRELOADED_SYMBOLS();
}
/// @todo enable
// static void preloadedSymbols(const std::string& lib,
// const lt_dlsymlist symbols[])
// throw(std::exception) {
// Lib lib(lt_dlopenext(lib.c_str()));
// LTDL_SET_PRELOADED_SYMBOLS(symbols);
// }
/** @brief append a directory to the library search path */
static void addSearchDir(const std::string& dir) throw(std::exception) {
if (lt_dladdsearchdir(dir.c_str())!=0)
throw failure("cannot add search dir: "+dir);
}
/** @brief insert a directory at a given position to the library
search path */
static void insertSearchDir(const std::string& before,
const std::string& dir)
throw(std::exception) {
if (lt_dlinsertsearchdir(before.c_str(), dir.c_str())!=0)
throw failure("cannot add search dir: "+dir);
}
/// @todo enable
// static std::string void setSearchPath(const std::string& dir) throw() {
// char const * const path(lt_dlgetsearchpath());
// if (!path)
// throw failure("cannot get search path");
// return path;
// }
/** @brief set the library search path
The search path is a colon separated list of paths. */
static void setSearchPath(const std::string& dirs) throw() {
if (lt_dlsetsearchpath(dirs.c_str()))
throw failure("cannot set search path to "+dirs);
}
/** @brief get the library search path */
static std::string getSearchPath() throw() {
char const * const path(lt_dlgetsearchpath());
if (!path)
throw failure("cannot get search path");
return path;
}
/** @brief calls a callback function for all directories in a
search path
In some applications you may not want to load individual
modules with known names, but rather find all of the modules
in a set of directories and load them all during
initialisation. With this function you can have
DynamicLibrary scan the colon delimited directory list in
searchPath for candidates, and pass them, along with data to
your own callback function, function. If searchPath is @c 0,
then search all of the standard locations that open would
examine. This function will continue to make calls to
function for each file that it discovers in searchPath until
one of these calls returns non-zero, or until the files are
exhausted.
@return value returned by the last call made to function
*/
int foreachfile(const char* searchPath,
int(*function)(const char*, lt_ptr),
lt_ptr data) throw() {
return lt_dlforeachfile(searchPath, function, data);
}
private:
class Lib {
Lib() throw(): _lib(0) {}
Lib(const std::string& lib) throw(std::exception): _lib(0) {
open(lib);
}
~Lib() throw() {
try {close();} catch(...) {}
}
operator bool() throw() {
return _lib;
}
Lib& open(const std::string& lib) throw(std::exception) {
close();
if (!(_lib = lt_dlopenext(lib.c_str())))
throw failure("cannot open dynamic library "+lib);
return *this;
}
Lib& close() throw(std::exception) {
if (_lib && lt_dlclose(_lib)!=0)
throw failure("cannot close dynamic library");
_lib = 0;
return *this;
}
private:
friend class DynamicLibrary;
lt_dlhandle handle() throw(std::exception) {
if (!_lib)
throw failure("library not open");
return _lib;
}
private:
lt_dlhandle _lib;
};
private:
bool _opened;
Lib _lib;
};
//@}
}
#endif

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