gmodule.c revision 0df89d51a4a9c5cdefa0a9f4c754958b054e9256 
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 * MT safe
22 */
23
24#include	"gmodule.h"
25#include	"gmoduleconf.h"
26#include	<errno.h>
27#include	<string.h>
28
29
30/* We maintain a list of modules, so we can reference count them.
31 * That's needed because some platforms don't support refernce counts on
32 * modules e.g. the shl_* implementation of HP-UX
33 * (http://www.stat.umn.edu/~luke/xls/projects/dlbasics/dlbasics.html).
34 * Also, the module for the program itself is kept seperatedly for
35 * faster access and because it has special semantics.
36 */
37
38
39/* --- structures --- */
40struct _GModule
41{
42  gchar	*file_name;
43  gpointer handle;
44  guint ref_count : 31;
45  guint is_resident : 1;
46  GModuleUnload unload;
47  GModule *next;
48};
49
50
51/* --- prototypes --- */
52static gpointer		_g_module_open		(const gchar	*file_name,
53						 gboolean	 bind_lazy);
54static void		_g_module_close		(gpointer	 handle,
55						 gboolean	 is_unref);
56static gpointer		_g_module_self		(void);
57static gpointer		_g_module_symbol	(gpointer	 handle,
58						 const gchar	*symbol_name);
59static gchar*		_g_module_build_path	(const gchar	*directory,
60						 const gchar	*module_name);
61static inline void	g_module_set_error	(const gchar	*error);
62static inline GModule*	g_module_find_by_handle (gpointer	 handle);
63static inline GModule*	g_module_find_by_name	(const gchar	*name);
64
65
66/* --- variables --- */
67G_LOCK_DEFINE_STATIC (GModule);
68const char           *g_log_domain_gmodule = "GModule";
69static GModule	     *modules = NULL;
70static GModule	     *main_module = NULL;
71static GStaticPrivate module_error_private = G_STATIC_PRIVATE_INIT;
72
73
74/* --- inline functions --- */
75static inline GModule*
76g_module_find_by_handle (gpointer handle)
77{
78  GModule *module;
79  GModule *retval = NULL;
80
81  G_LOCK (GModule);
82  if (main_module && main_module->handle == handle)
83    retval = main_module;
84  else
85    for (module = modules; module; module = module->next)
86      if (handle == module->handle)
87	{
88	  retval = module;
89	  break;
90	}
91  G_UNLOCK (GModule);
92
93  return retval;
94}
95
96static inline GModule*
97g_module_find_by_name (const gchar *name)
98{
99  GModule *module;
100  GModule *retval = NULL;
101
102  G_LOCK (GModule);
103  for (module = modules; module; module = module->next)
104    if (strcmp (name, module->file_name) == 0)
105	{
106	  retval = module;
107	  break;
108	}
109  G_UNLOCK (GModule);
110
111  return retval;
112}
113
114static inline void
115g_module_set_error (const gchar *error)
116{
117  g_static_private_set (&module_error_private, g_strdup (error), g_free);
118  errno = 0;
119}
120
121
122/* --- include platform specifc code --- */
123#define	CHECK_ERROR(rv)	{ g_module_set_error (NULL); }
124#if	(G_MODULE_IMPL == G_MODULE_IMPL_DL)
125#include "gmodule-dl.c"
126#elif	(G_MODULE_IMPL == G_MODULE_IMPL_DLD)
127#include "gmodule-dld.c"
128#elif	(G_MODULE_IMPL == G_MODULE_IMPL_WIN32)
129#include "gmodule-win32.c"
130#else
131#undef	CHECK_ERROR
132#define	CHECK_ERROR(rv)	{ g_module_set_error ("dynamic modules are " \
133                                              "not supported by this system"); return rv; }
134static gpointer
135_g_module_open (const gchar	*file_name,
136		gboolean	 bind_lazy)
137{
138  return NULL;
139}
140static void
141_g_module_close	(gpointer	 handle,
142		 gboolean	 is_unref)
143{
144}
145static gpointer
146_g_module_self (void)
147{
148  return NULL;
149}
150static gpointer
151_g_module_symbol (gpointer	 handle,
152		  const gchar	*symbol_name)
153{
154  return NULL;
155}
156static gchar*
157_g_module_build_path (const gchar *directory,
158		      const gchar *module_name)
159{
160  return NULL;
161}
162#endif	/* no implementation */
163
164#if defined (NATIVE_WIN32) && defined (__LCC__)
165int __stdcall
166LibMain (void         *hinstDll,
167	 unsigned long dwReason,
168	 void         *reserved)
169{
170  return 1;
171}
172#endif /* NATIVE_WIN32 && __LCC__ */
173
174
175/* --- functions --- */
176gboolean
177g_module_supported (void)
178{
179  CHECK_ERROR (FALSE);
180
181  return TRUE;
182}
183
184GModule*
185g_module_open (const gchar    *file_name,
186	       GModuleFlags    flags)
187{
188  GModule *module;
189  gpointer handle;
190
191  CHECK_ERROR (NULL);
192
193  if (!file_name)
194    {
195      G_LOCK (GModule);
196      if (!main_module)
197	{
198	  handle = _g_module_self ();
199	  if (handle)
200	    {
201	      main_module = g_new (GModule, 1);
202	      main_module->file_name = NULL;
203	      main_module->handle = handle;
204	      main_module->ref_count = 1;
205	      main_module->is_resident = TRUE;
206	      main_module->unload = NULL;
207	      main_module->next = NULL;
208	    }
209	}
210      G_UNLOCK (GModule);
211
212      return main_module;
213    }
214
215  /* we first search the module list by name */
216  module = g_module_find_by_name (file_name);
217  if (module)
218    {
219      module->ref_count++;
220
221      return module;
222    }
223
224  /* open the module */
225  handle = _g_module_open (file_name, (flags & G_MODULE_BIND_LAZY) != 0);
226  if (handle)
227    {
228      gchar *saved_error;
229      GModuleCheckInit check_init;
230      const gchar *check_failed = NULL;
231
232      /* search the module list by handle, since file names are not unique */
233      module = g_module_find_by_handle (handle);
234      if (module)
235	{
236	  _g_module_close (module->handle, TRUE);
237	  module->ref_count++;
238	  g_module_set_error (NULL);
239
240	  return module;
241	}
242
243      saved_error = g_strdup (g_module_error ());
244      g_module_set_error (NULL);
245
246      module = g_new (GModule, 1);
247      module->file_name = g_strdup (file_name);
248      module->handle = handle;
249      module->ref_count = 1;
250      module->is_resident = FALSE;
251      module->unload = NULL;
252      G_LOCK (GModule);
253      module->next = modules;
254      modules = module;
255      G_UNLOCK (GModule);
256
257      /* check initialization */
258      if (g_module_symbol (module, "g_module_check_init", (gpointer) &check_init))
259	check_failed = check_init (module);
260
261      /* we don't call unload() if the initialization check failed. */
262      if (!check_failed)
263	g_module_symbol (module, "g_module_unload", (gpointer) &module->unload);
264
265      if (check_failed)
266	{
267	  gchar *error;
268
269	  error = g_strconcat ("GModule initialization check failed: ", check_failed, NULL);
270	  g_module_close (module);
271	  module = NULL;
272	  g_module_set_error (error);
273	  g_free (error);
274	}
275      else
276	g_module_set_error (saved_error);
277
278      g_free (saved_error);
279    }
280
281  return module;
282}
283
284gboolean
285g_module_close (GModule	       *module)
286{
287  CHECK_ERROR (FALSE);
288
289  g_return_val_if_fail (module != NULL, FALSE);
290  g_return_val_if_fail (module->ref_count > 0, FALSE);
291
292  module->ref_count--;
293
294  if (!module->ref_count && !module->is_resident && module->unload)
295    {
296      GModuleUnload unload;
297
298      unload = module->unload;
299      module->unload = NULL;
300      unload (module);
301    }
302
303  if (!module->ref_count && !module->is_resident)
304    {
305      GModule *last;
306      GModule *node;
307
308      last = NULL;
309
310      G_LOCK (GModule);
311      node = modules;
312      while (node)
313	{
314	  if (node == module)
315	    {
316	      if (last)
317		last->next = node->next;
318	      else
319		modules = node->next;
320	      break;
321	    }
322	  last = node;
323	  node = last->next;
324	}
325      module->next = NULL;
326      G_UNLOCK (GModule);
327
328      _g_module_close (module->handle, FALSE);
329      g_free (module->file_name);
330
331      g_free (module);
332    }
333
334  return g_module_error() == NULL;
335}
336
337void
338g_module_make_resident (GModule *module)
339{
340  g_return_if_fail (module != NULL);
341
342  module->is_resident = TRUE;
343}
344
345gchar*
346g_module_error (void)
347{
348  return g_static_private_get (&module_error_private);
349}
350
351gboolean
352g_module_symbol (GModule	*module,
353		 const gchar	*symbol_name,
354		 gpointer	*symbol)
355{
356  gchar *module_error;
357  if (symbol)
358    *symbol = NULL;
359  CHECK_ERROR (FALSE);
360
361  g_return_val_if_fail (module != NULL, FALSE);
362  g_return_val_if_fail (symbol_name != NULL, FALSE);
363  g_return_val_if_fail (symbol != NULL, FALSE);
364
365#ifdef	G_MODULE_NEED_USCORE
366  {
367    gchar *name;
368
369    name = g_strconcat ("_", symbol_name, NULL);
370    *symbol = _g_module_symbol (module->handle, name);
371    g_free (name);
372  }
373#else	/* !G_MODULE_NEED_USCORE */
374  *symbol = _g_module_symbol (module->handle, symbol_name);
375#endif	/* !G_MODULE_NEED_USCORE */
376
377  if ((module_error = g_module_error()))
378    {
379      gchar *error;
380
381      error = g_strconcat ("`", symbol_name, "': ", module_error, NULL);
382      g_module_set_error (error);
383      g_free (error);
384      *symbol = NULL;
385      return FALSE;
386    }
387
388  return TRUE;
389}
390
391gchar*
392g_module_name (GModule *module)
393{
394  g_return_val_if_fail (module != NULL, NULL);
395
396  if (module == main_module)
397    return "main";
398
399  return module->file_name;
400}
401
402gchar*
403g_module_build_path (const gchar *directory,
404		     const gchar *module_name)
405{
406  g_return_val_if_fail (module_name != NULL, NULL);
407
408  return _g_module_build_path (directory, module_name);
409}
410