1 /* GMODULE - GLIB wrapper code for dynamic module loading
2 * Copyright (C) 1998 Tim Janik
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
19 * Modified by the GLib Team and others 1997-2000. See the AUTHORS
20 * file for a list of people on the GLib Team. See the ChangeLog
21 * files for a list of changes. These files are distributed with
22 * GLib at ftp://ftp.gtk.org/pub/gtk/.
36 #include <sys/types.h>
43 #include <io.h> /* For open() and close() prototypes. */
46 #include "gmoduleconf.h"
51 * @title: Dynamic Loading of Modules
52 * @short_description: portable method for dynamically loading 'plug-ins'
54 * These functions provide a portable way to dynamically load object files
55 * (commonly known as 'plug-ins'). The current implementation supports all
56 * systems that provide an implementation of dlopen() (e.g. Linux/Sun), as
57 * well as Windows platforms via DLLs.
59 * A program which wants to use these functions must be linked to the
60 * libraries output by the command `pkg-config --libs gmodule-2.0`.
62 * To use them you must first determine whether dynamic loading
63 * is supported on the platform by calling g_module_supported().
64 * If it is, you can open a module with g_module_open(),
65 * find the module's symbols (e.g. function names) with g_module_symbol(),
66 * and later close the module with g_module_close().
67 * g_module_name() will return the file name of a currently opened module.
69 * If any of the above functions fail, the error status can be found with
72 * The #GModule implementation features reference counting for opened modules,
73 * and supports hook functions within a module which are called when the
74 * module is loaded and unloaded (see #GModuleCheckInit and #GModuleUnload).
76 * If your module introduces static data to common subsystems in the running
77 * program, e.g. through calling
78 * `g_quark_from_static_string ("my-module-stuff")`,
79 * it must ensure that it is never unloaded, by calling g_module_make_resident().
81 * Example: Calling a function defined in a GModule
82 * |[<!-- language="C" -->
83 * // the function signature for 'say_hello'
84 * typedef void (* SayHelloFunc) (const char *message);
87 * just_say_hello (const char *filename, GError **error)
89 * SayHelloFunc say_hello;
92 * module = g_module_open (filename, G_MODULE_BIND_LAZY);
95 * g_set_error (error, FOO_ERROR, FOO_ERROR_BLAH,
96 * "%s", g_module_error ());
100 * if (!g_module_symbol (module, "say_hello", (gpointer *)&say_hello))
102 * g_set_error (error, SAY_ERROR, SAY_ERROR_OPEN,
103 * "%s: %s", filename, g_module_error ());
104 * if (!g_module_close (module))
105 * g_warning ("%s: %s", filename, g_module_error ());
109 * if (say_hello == NULL)
111 * g_set_error (error, SAY_ERROR, SAY_ERROR_OPEN,
112 * "symbol say_hello is NULL");
113 * if (!g_module_close (module))
114 * g_warning ("%s: %s", filename, g_module_error ());
118 * // call our function in the module
119 * say_hello ("Hello world!");
121 * if (!g_module_close (module))
122 * g_warning ("%s: %s", filename, g_module_error ());
131 * The #GModule struct is an opaque data structure to represent a
132 * [dynamically-loaded module][glib-Dynamic-Loading-of-Modules].
133 * It should only be accessed via the following functions.
138 * @module: the #GModule corresponding to the module which has just been loaded
140 * Specifies the type of the module initialization function.
141 * If a module contains a function named g_module_check_init() it is called
142 * automatically when the module is loaded. It is passed the #GModule structure
143 * and should return %NULL on success or a string describing the initialization
146 * Returns: %NULL on success, or a string describing the initialization error
151 * @module: the #GModule about to be unloaded
153 * Specifies the type of the module function called when it is unloaded.
154 * If a module contains a function named g_module_unload() it is called
155 * automatically when the module is unloaded.
156 * It is passed the #GModule structure.
162 * Expands to the proper shared library suffix for the current platform
163 * without the leading dot. For most Unices and Linux this is "so", and
164 * for Windows this is "dll".
170 * Used to declare functions exported by libraries or modules.
172 * When compiling for Windows, it marks the symbol as `dllexport`.
174 * When compiling for Linux and Unices, it marks the symbol as having `default`
175 * visibility. This is no-op unless the code is being compiled with a
177 * [visibility flag](https://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html#index-fvisibility-1260)
184 * Used to declare functions imported from modules.
187 /* We maintain a list of modules, so we can reference count them.
188 * That's needed because some platforms don't support references counts on
189 * modules. Also, the module for the program itself is kept seperately for
190 * faster access and because it has special semantics.
194 /* --- structures --- */
199 guint ref_count
: 31;
200 guint is_resident
: 1;
201 GModuleUnload unload
;
206 /* --- prototypes --- */
207 static gpointer
_g_module_open (const gchar
*file_name
,
209 gboolean bind_local
);
210 static void _g_module_close (gpointer handle
,
212 static gpointer
_g_module_self (void);
213 static gpointer
_g_module_symbol (gpointer handle
,
214 const gchar
*symbol_name
);
215 static gchar
* _g_module_build_path (const gchar
*directory
,
216 const gchar
*module_name
);
217 static inline void g_module_set_error (const gchar
*error
);
218 static inline GModule
* g_module_find_by_handle (gpointer handle
);
219 static inline GModule
* g_module_find_by_name (const gchar
*name
);
222 /* --- variables --- */
223 static GModule
*modules
= NULL
;
224 static GModule
*main_module
= NULL
;
225 static GPrivate module_error_private
= G_PRIVATE_INIT (g_free
);
226 static gboolean module_debug_initialized
= FALSE
;
227 static guint module_debug_flags
= 0;
230 /* --- inline functions --- */
231 static inline GModule
*
232 g_module_find_by_handle (gpointer handle
)
235 GModule
*retval
= NULL
;
237 if (main_module
&& main_module
->handle
== handle
)
238 retval
= main_module
;
240 for (module
= modules
; module
; module
= module
->next
)
241 if (handle
== module
->handle
)
250 static inline GModule
*
251 g_module_find_by_name (const gchar
*name
)
254 GModule
*retval
= NULL
;
256 for (module
= modules
; module
; module
= module
->next
)
257 if (strcmp (name
, module
->file_name
) == 0)
267 g_module_set_error_unduped (gchar
*error
)
269 g_private_replace (&module_error_private
, error
);
274 g_module_set_error (const gchar
*error
)
276 g_module_set_error_unduped (g_strdup (error
));
280 /* --- include platform specifc code --- */
281 #define SUPPORT_OR_RETURN(rv) { g_module_set_error (NULL); }
282 #if (G_MODULE_IMPL == G_MODULE_IMPL_DL)
283 #include "gmodule-dl.c"
284 #elif (G_MODULE_IMPL == G_MODULE_IMPL_WIN32)
285 #include "gmodule-win32.c"
286 #elif (G_MODULE_IMPL == G_MODULE_IMPL_DYLD)
287 #include "gmodule-dyld.c"
288 #elif (G_MODULE_IMPL == G_MODULE_IMPL_AR)
289 #include "gmodule-ar.c"
291 #undef SUPPORT_OR_RETURN
292 #define SUPPORT_OR_RETURN(rv) { g_module_set_error ("dynamic modules are " \
293 "not supported by this system"); return rv; }
295 _g_module_open (const gchar
*file_name
,
302 _g_module_close (gpointer handle
,
307 _g_module_self (void)
312 _g_module_symbol (gpointer handle
,
313 const gchar
*symbol_name
)
318 _g_module_build_path (const gchar
*directory
,
319 const gchar
*module_name
)
323 #endif /* no implementation */
325 /* --- functions --- */
328 * g_module_supported:
330 * Checks if modules are supported on the current platform.
332 * Returns: %TRUE if modules are supported
335 g_module_supported (void)
337 SUPPORT_OR_RETURN (FALSE
);
343 parse_libtool_archive (const gchar
* libtool_name
)
345 const guint TOKEN_DLNAME
= G_TOKEN_LAST
+ 1;
346 const guint TOKEN_INSTALLED
= G_TOKEN_LAST
+ 2;
347 const guint TOKEN_LIBDIR
= G_TOKEN_LAST
+ 3;
348 gchar
*lt_dlname
= NULL
;
349 gboolean lt_installed
= TRUE
;
350 gchar
*lt_libdir
= NULL
;
355 int fd
= g_open (libtool_name
, O_RDONLY
, 0);
358 gchar
*display_libtool_name
= g_filename_display_name (libtool_name
);
359 g_module_set_error_unduped (g_strdup_printf ("failed to open libtool archive \"%s\"", display_libtool_name
));
360 g_free (display_libtool_name
);
363 /* search libtool's dlname specification */
364 scanner
= g_scanner_new (NULL
);
365 g_scanner_input_file (scanner
, fd
);
366 scanner
->config
->symbol_2_token
= TRUE
;
367 g_scanner_scope_add_symbol (scanner
, 0, "dlname",
368 GUINT_TO_POINTER (TOKEN_DLNAME
));
369 g_scanner_scope_add_symbol (scanner
, 0, "installed",
370 GUINT_TO_POINTER (TOKEN_INSTALLED
));
371 g_scanner_scope_add_symbol (scanner
, 0, "libdir",
372 GUINT_TO_POINTER (TOKEN_LIBDIR
));
373 while (!g_scanner_eof (scanner
))
375 token
= g_scanner_get_next_token (scanner
);
376 if (token
== TOKEN_DLNAME
|| token
== TOKEN_INSTALLED
||
377 token
== TOKEN_LIBDIR
)
379 if (g_scanner_get_next_token (scanner
) != '=' ||
380 g_scanner_get_next_token (scanner
) !=
381 (token
== TOKEN_INSTALLED
?
382 G_TOKEN_IDENTIFIER
: G_TOKEN_STRING
))
384 gchar
*display_libtool_name
= g_filename_display_name (libtool_name
);
385 g_module_set_error_unduped (g_strdup_printf ("unable to parse libtool archive \"%s\"", display_libtool_name
));
386 g_free (display_libtool_name
);
390 g_scanner_destroy (scanner
);
397 if (token
== TOKEN_DLNAME
)
400 lt_dlname
= g_strdup (scanner
->value
.v_string
);
402 else if (token
== TOKEN_INSTALLED
)
404 strcmp (scanner
->value
.v_identifier
, "yes") == 0;
405 else /* token == TOKEN_LIBDIR */
408 lt_libdir
= g_strdup (scanner
->value
.v_string
);
416 gchar
*dir
= g_path_get_dirname (libtool_name
);
418 lt_libdir
= g_strconcat (dir
, G_DIR_SEPARATOR_S
".libs", NULL
);
422 name
= g_strconcat (lt_libdir
, G_DIR_SEPARATOR_S
, lt_dlname
, NULL
);
426 g_scanner_destroy (scanner
);
432 static inline gboolean
433 str_check_suffix (const gchar
* string
,
436 gsize string_len
= strlen (string
);
437 gsize suffix_len
= strlen (suffix
);
439 return string_len
>= suffix_len
&&
440 strcmp (string
+ string_len
- suffix_len
, suffix
) == 0;
445 G_MODULE_DEBUG_RESIDENT_MODULES
= 1 << 0,
446 G_MODULE_DEBUG_BIND_NOW_MODULES
= 1 << 1
450 _g_module_debug_init (void)
452 const GDebugKey keys
[] = {
453 { "resident-modules", G_MODULE_DEBUG_RESIDENT_MODULES
},
454 { "bind-now-modules", G_MODULE_DEBUG_BIND_NOW_MODULES
}
458 env
= g_getenv ("G_DEBUG");
461 !env
? 0 : g_parse_debug_string (env
, keys
, G_N_ELEMENTS (keys
));
463 module_debug_initialized
= TRUE
;
466 static GRecMutex g_module_global_lock
;
470 * @file_name: (nullable): the name of the file containing the module, or %NULL
471 * to obtain a #GModule representing the main program itself
472 * @flags: the flags used for opening the module. This can be the
473 * logical OR of any of the #GModuleFlags
475 * Opens a module. If the module has already been opened,
476 * its reference count is incremented.
478 * First of all g_module_open() tries to open @file_name as a module.
479 * If that fails and @file_name has the ".la"-suffix (and is a libtool
480 * archive) it tries to open the corresponding module. If that fails
481 * and it doesn't have the proper module suffix for the platform
482 * (#G_MODULE_SUFFIX), this suffix will be appended and the corresponding
483 * module will be opended. If that fails and @file_name doesn't have the
484 * ".la"-suffix, this suffix is appended and g_module_open() tries to open
485 * the corresponding module. If eventually that fails as well, %NULL is
488 * Returns: a #GModule on success, or %NULL on failure
491 g_module_open (const gchar
*file_name
,
495 gpointer handle
= NULL
;
498 SUPPORT_OR_RETURN (NULL
);
500 g_rec_mutex_lock (&g_module_global_lock
);
502 if (G_UNLIKELY (!module_debug_initialized
))
503 _g_module_debug_init ();
505 if (module_debug_flags
& G_MODULE_DEBUG_BIND_NOW_MODULES
)
506 flags
&= ~G_MODULE_BIND_LAZY
;
512 handle
= _g_module_self ();
513 /* On Android 64 bit, RTLD_DEFAULT is (void *)0x0
514 * so it always fails to create main_module if file_name is NULL */
515 #if !defined(__BIONIC__) || !defined(__LP64__)
519 main_module
= g_new (GModule
, 1);
520 main_module
->file_name
= NULL
;
521 main_module
->handle
= handle
;
522 main_module
->ref_count
= 1;
523 main_module
->is_resident
= TRUE
;
524 main_module
->unload
= NULL
;
525 main_module
->next
= NULL
;
529 main_module
->ref_count
++;
531 g_rec_mutex_unlock (&g_module_global_lock
);
535 /* we first search the module list by name */
536 module
= g_module_find_by_name (file_name
);
541 g_rec_mutex_unlock (&g_module_global_lock
);
545 /* check whether we have a readable file right away */
546 if (g_file_test (file_name
, G_FILE_TEST_IS_REGULAR
))
547 name
= g_strdup (file_name
);
548 /* try completing file name with standard library suffix */
551 name
= g_strconcat (file_name
, "." G_MODULE_SUFFIX
, NULL
);
552 if (!g_file_test (name
, G_FILE_TEST_IS_REGULAR
))
558 /* try completing by appending libtool suffix */
561 name
= g_strconcat (file_name
, ".la", NULL
);
562 if (!g_file_test (name
, G_FILE_TEST_IS_REGULAR
))
568 /* we can't access() the file, lets hope the platform backends finds
569 * it via library paths
573 gchar
*dot
= strrchr (file_name
, '.');
574 gchar
*slash
= strrchr (file_name
, G_DIR_SEPARATOR
);
576 /* make sure the name has a suffix */
577 if (!dot
|| dot
< slash
)
578 name
= g_strconcat (file_name
, "." G_MODULE_SUFFIX
, NULL
);
580 name
= g_strdup (file_name
);
583 /* ok, try loading the module */
586 /* if it's a libtool archive, figure library file to load */
587 if (str_check_suffix (name
, ".la")) /* libtool archive? */
589 gchar
*real_name
= parse_libtool_archive (name
);
591 /* real_name might be NULL, but then module error is already set */
599 handle
= _g_module_open (name
, (flags
& G_MODULE_BIND_LAZY
) != 0,
600 (flags
& G_MODULE_BIND_LOCAL
) != 0);
604 gchar
*display_file_name
= g_filename_display_name (file_name
);
605 g_module_set_error_unduped (g_strdup_printf ("unable to access file \"%s\"", display_file_name
));
606 g_free (display_file_name
);
613 GModuleCheckInit check_init
;
614 const gchar
*check_failed
= NULL
;
616 /* search the module list by handle, since file names are not unique */
617 module
= g_module_find_by_handle (handle
);
620 _g_module_close (module
->handle
, TRUE
);
622 g_module_set_error (NULL
);
624 g_rec_mutex_unlock (&g_module_global_lock
);
628 saved_error
= g_strdup (g_module_error ());
629 g_module_set_error (NULL
);
631 module
= g_new (GModule
, 1);
632 module
->file_name
= g_strdup (file_name
);
633 module
->handle
= handle
;
634 module
->ref_count
= 1;
635 module
->is_resident
= FALSE
;
636 module
->unload
= NULL
;
637 module
->next
= modules
;
640 /* check initialization */
641 if (g_module_symbol (module
, "g_module_check_init", (gpointer
) &check_init
) && check_init
!= NULL
)
642 check_failed
= check_init (module
);
644 /* we don't call unload() if the initialization check failed. */
646 g_module_symbol (module
, "g_module_unload", (gpointer
) &module
->unload
);
652 error
= g_strconcat ("GModule (", file_name
, ") ",
653 "initialization check failed: ",
655 g_module_close (module
);
657 g_module_set_error (error
);
661 g_module_set_error (saved_error
);
663 g_free (saved_error
);
666 if (module
!= NULL
&&
667 (module_debug_flags
& G_MODULE_DEBUG_RESIDENT_MODULES
))
668 g_module_make_resident (module
);
670 g_rec_mutex_unlock (&g_module_global_lock
);
676 * @module: a #GModule to close
680 * Returns: %TRUE on success
683 g_module_close (GModule
*module
)
685 SUPPORT_OR_RETURN (FALSE
);
687 g_return_val_if_fail (module
!= NULL
, FALSE
);
688 g_return_val_if_fail (module
->ref_count
> 0, FALSE
);
690 g_rec_mutex_lock (&g_module_global_lock
);
694 if (!module
->ref_count
&& !module
->is_resident
&& module
->unload
)
696 GModuleUnload unload
;
698 unload
= module
->unload
;
699 module
->unload
= NULL
;
703 if (!module
->ref_count
&& !module
->is_resident
)
716 last
->next
= node
->next
;
718 modules
= node
->next
;
726 _g_module_close (module
->handle
, FALSE
);
727 g_free (module
->file_name
);
731 g_rec_mutex_unlock (&g_module_global_lock
);
732 return g_module_error() == NULL
;
736 * g_module_make_resident:
737 * @module: a #GModule to make permanently resident
739 * Ensures that a module will never be unloaded.
740 * Any future g_module_close() calls on the module will be ignored.
743 g_module_make_resident (GModule
*module
)
745 g_return_if_fail (module
!= NULL
);
747 module
->is_resident
= TRUE
;
753 * Gets a string describing the last module error.
755 * Returns: a string describing the last module error
758 g_module_error (void)
760 return g_private_get (&module_error_private
);
765 * @module: a #GModule
766 * @symbol_name: the name of the symbol to find
767 * @symbol: (out): returns the pointer to the symbol value
769 * Gets a symbol pointer from a module, such as one exported
770 * by #G_MODULE_EXPORT. Note that a valid symbol can be %NULL.
772 * Returns: %TRUE on success
775 g_module_symbol (GModule
*module
,
776 const gchar
*symbol_name
,
779 const gchar
*module_error
;
783 SUPPORT_OR_RETURN (FALSE
);
785 g_return_val_if_fail (module
!= NULL
, FALSE
);
786 g_return_val_if_fail (symbol_name
!= NULL
, FALSE
);
787 g_return_val_if_fail (symbol
!= NULL
, FALSE
);
789 g_rec_mutex_lock (&g_module_global_lock
);
791 #ifdef G_MODULE_NEED_USCORE
795 name
= g_strconcat ("_", symbol_name
, NULL
);
796 *symbol
= _g_module_symbol (module
->handle
, name
);
799 #else /* !G_MODULE_NEED_USCORE */
800 *symbol
= _g_module_symbol (module
->handle
, symbol_name
);
801 #endif /* !G_MODULE_NEED_USCORE */
803 module_error
= g_module_error ();
808 error
= g_strconcat ("'", symbol_name
, "': ", module_error
, NULL
);
809 g_module_set_error (error
);
814 g_rec_mutex_unlock (&g_module_global_lock
);
815 return !module_error
;
820 * @module: a #GModule
822 * Returns the filename that the module was opened with.
824 * If @module refers to the application itself, "main" is returned.
826 * Returns: (transfer none): the filename of the module
829 g_module_name (GModule
*module
)
831 g_return_val_if_fail (module
!= NULL
, NULL
);
833 if (module
== main_module
)
836 return module
->file_name
;
840 * g_module_build_path:
841 * @directory: (nullable): the directory where the module is. This can be
842 * %NULL or the empty string to indicate that the standard platform-specific
843 * directories will be used, though that is not recommended
844 * @module_name: the name of the module
846 * A portable way to build the filename of a module. The platform-specific
847 * prefix and suffix are added to the filename, if needed, and the result
848 * is added to the directory, using the correct separator character.
850 * The directory should specify the directory where the module can be found.
851 * It can be %NULL or an empty string to indicate that the module is in a
852 * standard platform-specific directory, though this is not recommended
853 * since the wrong module may be found.
855 * For example, calling g_module_build_path() on a Linux system with a
856 * @directory of `/lib` and a @module_name of "mylibrary" will return
857 * `/lib/libmylibrary.so`. On a Windows system, using `\Windows` as the
858 * directory it will return `\Windows\mylibrary.dll`.
860 * Returns: the complete path of the module, including the standard library
861 * prefix and suffix. This should be freed when no longer needed
864 g_module_build_path (const gchar
*directory
,
865 const gchar
*module_name
)
867 g_return_val_if_fail (module_name
!= NULL
, NULL
);
869 return _g_module_build_path (directory
, module_name
);
875 /* Binary compatibility versions. Not for newly compiled code. */
877 _GLIB_EXTERN GModule
* g_module_open_utf8 (const gchar
*file_name
,
880 _GLIB_EXTERN
const gchar
*g_module_name_utf8 (GModule
*module
);
883 g_module_open_utf8 (const gchar
*file_name
,
886 return g_module_open (file_name
, flags
);
890 g_module_name_utf8 (GModule
*module
)
892 return g_module_name (module
);