source: squid-ssl/trunk/fuentes/libltdl/lt_dlloader.c @ 5496

Last change on this file since 5496 was 5496, checked in by Juanma, 22 months ago

Initial release

File size: 5.9 KB
Line 
1/* lt_dlloader.c -- dynamic library loader interface
2
3   Copyright (C) 2004, 2007, 2008 Free Software Foundation, Inc.
4   Written by Gary V. Vaughan, 2004
5
6   NOTE: The canonical source of this file is maintained with the
7   GNU Libtool package.  Report bugs to bug-libtool@gnu.org.
8
9GNU Libltdl is free software; you can redistribute it and/or
10modify it under the terms of the GNU Lesser General Public
11License as published by the Free Software Foundation; either
12version 2 of the License, or (at your option) any later version.
13
14As a special exception to the GNU Lesser General Public License,
15if you distribute this file as part of a program or library that
16is built using GNU Libtool, you may include this file under the
17same distribution terms that you use for the rest of that program.
18
19GNU Libltdl is distributed in the hope that it will be useful,
20but WITHOUT ANY WARRANTY; without even the implied warranty of
21MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
22GNU Lesser General Public License for more details.
23
24You should have received a copy of the GNU Lesser General Public
25License along with GNU Libltdl; see the file COPYING.LIB.  If not, a
26copy can be downloaded from  http://www.gnu.org/licenses/lgpl.html,
27or obtained by writing to the Free Software Foundation, Inc.,
2851 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
29*/
30
31#include "lt__private.h"
32#include "lt_dlloader.h"
33
34#define RETURN_SUCCESS 0
35#define RETURN_FAILURE 1
36
37static void *   loader_callback (SList *item, void *userdata);
38
39/* A list of all the dlloaders we know about, each stored as a boxed
40   SList item:  */
41static  SList    *loaders               = 0;
42
43
44/* Return NULL, unless the loader in this ITEM has a matching name,
45   in which case we return the matching item so that its address is
46   passed back out (for possible freeing) by slist_remove.  */
47static void *
48loader_callback (SList *item, void *userdata)
49{
50  const lt_dlvtable *vtable = (const lt_dlvtable *) item->userdata;
51  const char *      name    = (const char *) userdata;
52
53  assert (vtable);
54
55  return streq (vtable->name, name) ? (void *) item : NULL;
56}
57
58
59/* Hook VTABLE into our global LOADERS list according to its own
60   PRIORITY field value.  */
61int
62lt_dlloader_add (const lt_dlvtable *vtable)
63{
64  SList *item;
65
66  if ((vtable == 0)     /* diagnose invalid vtable fields */
67      || (vtable->module_open == 0)
68      || (vtable->module_close == 0)
69      || (vtable->find_sym == 0)
70      || ((vtable->priority != LT_DLLOADER_PREPEND) &&
71          (vtable->priority != LT_DLLOADER_APPEND)))
72    {
73      LT__SETERROR (INVALID_LOADER);
74      return RETURN_FAILURE;
75    }
76
77  item = slist_box (vtable);
78  if (!item)
79    {
80      (*lt__alloc_die) ();
81
82      /* Let the caller know something went wrong if lt__alloc_die
83         doesn't abort.  */
84      return RETURN_FAILURE;
85    }
86
87  if (vtable->priority == LT_DLLOADER_PREPEND)
88    {
89      loaders = slist_cons (item, loaders);
90    }
91  else
92    {
93      assert (vtable->priority == LT_DLLOADER_APPEND);
94      loaders = slist_concat (loaders, item);
95    }
96
97  return RETURN_SUCCESS;
98}
99
100#ifdef LT_DEBUG_LOADERS
101static void *
102loader_dump_callback (SList *item, void *userdata)
103{
104  const lt_dlvtable *vtable = (const lt_dlvtable *) item->userdata;
105  fprintf (stderr, ", %s", (vtable && vtable->name) ? vtable->name : "(null)");
106  return 0;
107}
108
109void
110lt_dlloader_dump (void)
111{
112  fprintf (stderr, "loaders: ");
113  if (!loaders)
114    {
115      fprintf (stderr, "(empty)");
116    }
117  else
118    {
119      const lt_dlvtable *head = (const lt_dlvtable *) loaders->userdata;
120      fprintf (stderr, "%s", (head && head->name) ? head->name : "(null)");
121      if (slist_tail (loaders))
122        slist_foreach (slist_tail (loaders), loader_dump_callback, NULL);
123    }
124  fprintf (stderr, "\n");
125}
126#endif
127
128/* An iterator for the global loader list: if LOADER is NULL, then
129   return the first element, otherwise the following element.  */
130lt_dlloader
131lt_dlloader_next (lt_dlloader loader)
132{
133  SList *item = (SList *) loader;
134  return (lt_dlloader) (item ? item->next : loaders);
135}
136
137
138/* Non-destructive unboxing of a loader.  */
139const lt_dlvtable *
140lt_dlloader_get (lt_dlloader loader)
141{
142  return (const lt_dlvtable *) (loader ? ((SList *) loader)->userdata : NULL);
143}
144
145
146/* Return the contents of the first item in the global loader list
147   with a matching NAME after removing it from that list.  If there
148   was no match, return NULL; if there is an error, return NULL and
149   set an error for lt_dlerror; do not set an error if only resident
150   modules need this loader; in either case, the loader list is not
151   changed if NULL is returned.  */
152lt_dlvtable *
153lt_dlloader_remove (const char *name)
154{
155  const lt_dlvtable *   vtable  = lt_dlloader_find (name);
156  static const char     id_string[] = "lt_dlloader_remove";
157  lt_dlinterface_id     iface;
158  lt_dlhandle           handle = 0;
159  int                   in_use = 0;
160  int                   in_use_by_resident = 0;
161
162  if (!vtable)
163    {
164      LT__SETERROR (INVALID_LOADER);
165      return 0;
166    }
167
168  /* Fail if there are any open modules which use this loader.  */
169  iface = lt_dlinterface_register (id_string, NULL);
170  while ((handle = lt_dlhandle_iterate (iface, handle)))
171    {
172      lt_dlhandle cur = handle;
173      if (cur->vtable == vtable)
174        {
175          in_use = 1;
176          if (lt_dlisresident (handle))
177            in_use_by_resident = 1;
178        }
179    }
180  lt_dlinterface_free (iface);
181  if (in_use)
182    {
183      if (!in_use_by_resident)
184        LT__SETERROR (REMOVE_LOADER);
185      return 0;
186    }
187
188  /* Call the loader finalisation function.  */
189  if (vtable && vtable->dlloader_exit)
190    {
191      if ((*vtable->dlloader_exit) (vtable->dlloader_data) != 0)
192        {
193          /* If there is an exit function, and it returns non-zero
194             then it must set an error, and we will not remove it
195             from the list.  */
196          return 0;
197        }
198    }
199
200  /* If we got this far, remove the loader from our global list.  */
201  return (lt_dlvtable *)
202      slist_unbox ((SList *) slist_remove (&loaders, loader_callback, (void *) name));
203}
204
205
206const lt_dlvtable *
207lt_dlloader_find (const char *name)
208{
209  return lt_dlloader_get (slist_find (loaders, loader_callback, (void *) name));
210}
Note: See TracBrowser for help on using the repository browser.