gmodule.c revision b9ef2b41db975061960e2217220668c2a5d563da 
1/* GMODULE - GLIB wrapper code for dynamic module loading
2 * Copyright (C) 1998 Tim Janik
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
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 * Library General Public License for more details.
13 *
14 * You should have received a copy of the GNU Library General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
18 */
19
20/*
21 * Modified by the GLib Team and others 1997-1999.  See the AUTHORS
22 * file for a list of people on the GLib Team.  See the ChangeLog
23 * files for a list of changes.  These files are distributed with
24 * GLib at ftp://ftp.gtk.org/pub/gtk/.
25 */
26
27/*
28 * MT safe
29 */
30
31#include	"gmodule.h"
32#include	"gmoduleconf.h"
33#include	<errno.h>
34#include	<string.h>
35
36
37/* We maintain a list of modules, so we can reference count them.
38 * That's needed because some platforms don't support refernce counts on
39 * modules e.g. the shl_* implementation of HP-UX
40 * (http://www.stat.umn.edu/~luke/xls/projects/dlbasics/dlbasics.html).
41 * Also, the module for the program itself is kept seperatedly for
42 * faster access and because it has special semantics.
43 */
44
45
46/* --- structures --- */
47struct _GModule
48{
49  gchar	*file_name;
50  gpointer handle;
51  guint ref_count : 31;
52  guint is_resident : 1;
53  GModuleUnload unload;
54  GModule *next;
55};
56
57
58/* --- prototypes --- */
59static gpointer		_g_module_open		(const gchar	*file_name,
60						 gboolean	 bind_lazy);
61static void		_g_module_close		(gpointer	 handle,
62						 gboolean	 is_unref);
63static gpointer		_g_module_self		(void);
64static gpointer		_g_module_symbol	(gpointer	 handle,
65						 const gchar	*symbol_name);
66static gchar*		_g_module_build_path	(const gchar	*directory,
67						 const gchar	*module_name);
68static inline void	g_module_set_error	(const gchar	*error);
69static inline GModule*	g_module_find_by_handle (gpointer	 handle);
70static inline GModule*	g_module_find_by_name	(const gchar	*name);
71
72
73/* --- variables --- */
74G_LOCK_DEFINE_STATIC (GModule);
75const char           *g_log_domain_gmodule = "GModule";
76static GModule	     *modules = NULL;
77static GModule	     *main_module = NULL;
78static GStaticPrivate module_error_private = G_STATIC_PRIVATE_INIT;
79
80
81/* --- inline functions --- */
82static inline GModule*
83g_module_find_by_handle (gpointer handle)
84{
85  GModule *module;
86  GModule *retval = NULL;
87
88  G_LOCK (GModule);
89  if (main_module && main_module->handle == handle)
90    retval = main_module;
91  else
92    for (module = modules; module; module = module->next)
93      if (handle == module->handle)
94	{
95	  retval = module;
96	  break;
97	}
98  G_UNLOCK (GModule);
99
100  return retval;
101}
102
103static inline GModule*
104g_module_find_by_name (const gchar *name)
105{
106  GModule *module;
107  GModule *retval = NULL;
108
109  G_LOCK (GModule);
110  for (module = modules; module; module = module->next)
111    if (strcmp (name, module->file_name) == 0)
112	{
113	  retval = module;
114	  break;
115	}
116  G_UNLOCK (GModule);
117
118  return retval;
119}
120
121static inline void
122g_module_set_error (const gchar *error)
123{
124  g_static_private_set (&module_error_private, g_strdup (error), g_free);
125  errno = 0;
126}
127
128
129/* --- include platform specifc code --- */
130#define	CHECK_ERROR(rv)	{ g_module_set_error (NULL); }
131#if	(G_MODULE_IMPL == G_MODULE_IMPL_DL)
132#include "gmodule-dl.c"
133#elif	(G_MODULE_IMPL == G_MODULE_IMPL_DLD)
134#include "gmodule-dld.c"
135#elif	(G_MODULE_IMPL == G_MODULE_IMPL_WIN32)
136#include "gmodule-win32.c"
137#else
138#undef	CHECK_ERROR
139#define	CHECK_ERROR(rv)	{ g_module_set_error ("dynamic modules are " \
140                                              "not supported by this system"); return rv; }
141static gpointer
142_g_module_open (const gchar	*file_name,
143		gboolean	 bind_lazy)
144{
145  return NULL;
146}
147static void
148_g_module_close	(gpointer	 handle,
149		 gboolean	 is_unref)
150{
151}
152static gpointer
153_g_module_self (void)
154{
155  return NULL;
156}
157static gpointer
158_g_module_symbol (gpointer	 handle,
159		  const gchar	*symbol_name)
160{
161  return NULL;
162}
163static gchar*
164_g_module_build_path (const gchar *directory,
165		      const gchar *module_name)
166{
167  return NULL;
168}
169#endif	/* no implementation */
170
171#if defined (NATIVE_WIN32) && defined (__LCC__)
172int __stdcall
173LibMain (void         *hinstDll,
174	 unsigned long dwReason,
175	 void         *reserved)
176{
177  return 1;
178}
179#endif /* NATIVE_WIN32 && __LCC__ */
180
181
182/* --- functions --- */
183gboolean
184g_module_supported (void)
185{
186  CHECK_ERROR (FALSE);
187
188  return TRUE;
189}
190
191GModule*
192g_module_open (const gchar    *file_name,
193	       GModuleFlags    flags)
194{
195  GModule *module;
196  gpointer handle;
197
198  CHECK_ERROR (NULL);
199
200  if (!file_name)
201    {
202      G_LOCK (GModule);
203      if (!main_module)
204	{
205	  handle = _g_module_self ();
206	  if (handle)
207	    {
208	      main_module = g_new (GModule, 1);
209	      main_module->file_name = NULL;
210	      main_module->handle = handle;
211	      main_module->ref_count = 1;
212	      main_module->is_resident = TRUE;
213	      main_module->unload = NULL;
214	      main_module->next = NULL;
215	    }
216	}
217      G_UNLOCK (GModule);
218
219      return main_module;
220    }
221
222  /* we first search the module list by name */
223  module = g_module_find_by_name (file_name);
224  if (module)
225    {
226      module->ref_count++;
227
228      return module;
229    }
230
231  /* open the module */
232  handle = _g_module_open (file_name, (flags & G_MODULE_BIND_LAZY) != 0);
233  if (handle)
234    {
235      gchar *saved_error;
236      GModuleCheckInit check_init;
237      const gchar *check_failed = NULL;
238
239      /* search the module list by handle, since file names are not unique */
240      module = g_module_find_by_handle (handle);
241      if (module)
242	{
243	  _g_module_close (module->handle, TRUE);
244	  module->ref_count++;
245	  g_module_set_error (NULL);
246
247	  return module;
248	}
249
250      saved_error = g_strdup (g_module_error ());
251      g_module_set_error (NULL);
252
253      module = g_new (GModule, 1);
254      module->file_name = g_strdup (file_name);
255      module->handle = handle;
256      module->ref_count = 1;
257      module->is_resident = FALSE;
258      module->unload = NULL;
259      G_LOCK (GModule);
260      module->next = modules;
261      modules = module;
262      G_UNLOCK (GModule);
263
264      /* check initialization */
265      if (g_module_symbol (module, "g_module_check_init", (gpointer) &check_init))
266	check_failed = check_init (module);
267
268      /* we don't call unload() if the initialization check failed. */
269      if (!check_failed)
270	g_module_symbol (module, "g_module_unload", (gpointer) &module->unload);
271
272      if (check_failed)
273	{
274	  gchar *error;
275
276	  error = g_strconcat ("GModule initialization check failed: ", check_failed, NULL);
277	  g_module_close (module);
278	  module = NULL;
279	  g_module_set_error (error);
280	  g_free (error);
281	}
282      else
283	g_module_set_error (saved_error);
284
285      g_free (saved_error);
286    }
287
288  return module;
289}
290
291gboolean
292g_module_close (GModule	       *module)
293{
294  CHECK_ERROR (FALSE);
295
296  g_return_val_if_fail (module != NULL, FALSE);
297  g_return_val_if_fail (module->ref_count > 0, FALSE);
298
299  module->ref_count--;
300
301  if (!module->ref_count && !module->is_resident && module->unload)
302    {
303      GModuleUnload unload;
304
305      unload = module->unload;
306      module->unload = NULL;
307      unload (module);
308    }
309
310  if (!module->ref_count && !module->is_resident)
311    {
312      GModule *last;
313      GModule *node;
314
315      last = NULL;
316
317      G_LOCK (GModule);
318      node = modules;
319      while (node)
320	{
321	  if (node == module)
322	    {
323	      if (last)
324		last->next = node->next;
325	      else
326		modules = node->next;
327	      break;
328	    }
329	  last = node;
330	  node = last->next;
331	}
332      module->next = NULL;
333      G_UNLOCK (GModule);
334
335      _g_module_close (module->handle, FALSE);
336      g_free (module->file_name);
337
338      g_free (module);
339    }
340
341  return g_module_error() == NULL;
342}
343
344void
345g_module_make_resident (GModule *module)
346{
347  g_return_if_fail (module != NULL);
348
349  module->is_resident = TRUE;
350}
351
352gchar*
353g_module_error (void)
354{
355  return g_static_private_get (&module_error_private);
356}
357
358gboolean
359g_module_symbol (GModule	*module,
360		 const gchar	*symbol_name,
361		 gpointer	*symbol)
362{
363  gchar *module_error;
364  if (symbol)
365    *symbol = NULL;
366  CHECK_ERROR (FALSE);
367
368  g_return_val_if_fail (module != NULL, FALSE);
369  g_return_val_if_fail (symbol_name != NULL, FALSE);
370  g_return_val_if_fail (symbol != NULL, FALSE);
371
372#ifdef	G_MODULE_NEED_USCORE
373  {
374    gchar *name;
375
376    name = g_strconcat ("_", symbol_name, NULL);
377    *symbol = _g_module_symbol (module->handle, name);
378    g_free (name);
379  }
380#else	/* !G_MODULE_NEED_USCORE */
381  *symbol = _g_module_symbol (module->handle, symbol_name);
382#endif	/* !G_MODULE_NEED_USCORE */
383
384  if ((module_error = g_module_error()))
385    {
386      gchar *error;
387
388      error = g_strconcat ("`", symbol_name, "': ", module_error, NULL);
389      g_module_set_error (error);
390      g_free (error);
391      *symbol = NULL;
392      return FALSE;
393    }
394
395  return TRUE;
396}
397
398gchar*
399g_module_name (GModule *module)
400{
401  g_return_val_if_fail (module != NULL, NULL);
402
403  if (module == main_module)
404    return "main";
405
406  return module->file_name;
407}
408
409gchar*
410g_module_build_path (const gchar *directory,
411		     const gchar *module_name)
412{
413  g_return_val_if_fail (module_name != NULL, NULL);
414
415  return _g_module_build_path (directory, module_name);
416}
417