source: squid-ssl/trunk/fuentes/libltdl/lt_dlloader.c @ 5495

Last change on this file since 5495 was 5495, checked in by Juanma, 2 years ago

Initial release

File size: 5.9 KB
Line 
1/* lt_dlloader.c -- dynamic library loader interface
2
3   Copyright (C) 2004, 2007-2008, 2011-2015 Free Software Foundation,
4   Inc.
5   Written by Gary V. Vaughan, 2004
6
7   NOTE: The canonical source of this file is maintained with the
8   GNU Libtool package.  Report bugs to bug-libtool@gnu.org.
9
10GNU Libltdl is free software; you can redistribute it and/or
11modify it under the terms of the GNU Lesser General Public
12License as published by the Free Software Foundation; either
13version 2 of the License, or (at your option) any later version.
14
15As a special exception to the GNU Lesser General Public License,
16if you distribute this file as part of a program or library that
17is built using GNU Libtool, you may include this file under the
18same distribution terms that you use for the rest of that program.
19
20GNU Libltdl is distributed in the hope that it will be useful,
21but WITHOUT ANY WARRANTY; without even the implied warranty of
22MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
23GNU Lesser General Public License for more details.
24
25You should have received a copy of the GNU Lesser General Public
26License along with GNU Libltdl; see the file COPYING.LIB.  If not, a
27copy can be downloaded from  http://www.gnu.org/licenses/lgpl.html,
28or obtained by writing to the Free Software Foundation, Inc.,
2951 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
30*/
31
32#include "lt__private.h"
33#include "lt_dlloader.h"
34
35#define RETURN_SUCCESS 0
36#define RETURN_FAILURE 1
37
38static void *   loader_callback (SList *item, void *userdata);
39
40/* A list of all the dlloaders we know about, each stored as a boxed
41   SList item:  */
42static  SList    *loaders               = 0;
43
44
45/* Return NULL, unless the loader in this ITEM has a matching name,
46   in which case we return the matching item so that its address is
47   passed back out (for possible freeing) by slist_remove.  */
48static void *
49loader_callback (SList *item, void *userdata)
50{
51  const lt_dlvtable *vtable = (const lt_dlvtable *) item->userdata;
52  const char *      name    = (const char *) userdata;
53
54  assert (vtable);
55
56  return STREQ (vtable->name, name) ? (void *) item : NULL;
57}
58
59
60/* Hook VTABLE into our global LOADERS list according to its own
61   PRIORITY field value.  */
62int
63lt_dlloader_add (const lt_dlvtable *vtable)
64{
65  SList *item;
66
67  if ((vtable == 0)     /* diagnose invalid vtable fields */
68      || (vtable->module_open == 0)
69      || (vtable->module_close == 0)
70      || (vtable->find_sym == 0)
71      || ((vtable->priority != LT_DLLOADER_PREPEND) &&
72          (vtable->priority != LT_DLLOADER_APPEND)))
73    {
74      LT__SETERROR (INVALID_LOADER);
75      return RETURN_FAILURE;
76    }
77
78  item = slist_box (vtable);
79  if (!item)
80    {
81      (*lt__alloc_die) ();
82
83      /* Let the caller know something went wrong if lt__alloc_die
84         doesn't abort.  */
85      return RETURN_FAILURE;
86    }
87
88  if (vtable->priority == LT_DLLOADER_PREPEND)
89    {
90      loaders = slist_cons (item, loaders);
91    }
92  else
93    {
94      assert (vtable->priority == LT_DLLOADER_APPEND);
95      loaders = slist_concat (loaders, item);
96    }
97
98  return RETURN_SUCCESS;
99}
100
101#ifdef LT_DEBUG_LOADERS
102static void *
103loader_dump_callback (SList *item, void *userdata)
104{
105  const lt_dlvtable *vtable = (const lt_dlvtable *) item->userdata;
106  fprintf (stderr, ", %s", (vtable && vtable->name) ? vtable->name : "(null)");
107  return 0;
108}
109
110void
111lt_dlloader_dump (void)
112{
113  fprintf (stderr, "loaders: ");
114  if (!loaders)
115    {
116      fprintf (stderr, "(empty)");
117    }
118  else
119    {
120      const lt_dlvtable *head = (const lt_dlvtable *) loaders->userdata;
121      fprintf (stderr, "%s", (head && head->name) ? head->name : "(null)");
122      if (slist_tail (loaders))
123        slist_foreach (slist_tail (loaders), loader_dump_callback, NULL);
124    }
125  fprintf (stderr, "\n");
126}
127#endif
128
129/* An iterator for the global loader list: if LOADER is NULL, then
130   return the first element, otherwise the following element.  */
131lt_dlloader
132lt_dlloader_next (lt_dlloader loader)
133{
134  SList *item = (SList *) loader;
135  return (lt_dlloader) (item ? item->next : loaders);
136}
137
138
139/* Non-destructive unboxing of a loader.  */
140const lt_dlvtable *
141lt_dlloader_get (lt_dlloader loader)
142{
143  return (const lt_dlvtable *) (loader ? ((SList *) loader)->userdata : NULL);
144}
145
146
147/* Return the contents of the first item in the global loader list
148   with a matching NAME after removing it from that list.  If there
149   was no match, return NULL; if there is an error, return NULL and
150   set an error for lt_dlerror; do not set an error if only resident
151   modules need this loader; in either case, the loader list is not
152   changed if NULL is returned.  */
153lt_dlvtable *
154lt_dlloader_remove (const char *name)
155{
156  const lt_dlvtable *   vtable  = lt_dlloader_find (name);
157  static const char     id_string[] = "lt_dlloader_remove";
158  lt_dlinterface_id     iface;
159  lt_dlhandle           handle = 0;
160  int                   in_use = 0;
161  int                   in_use_by_resident = 0;
162
163  if (!vtable)
164    {
165      LT__SETERROR (INVALID_LOADER);
166      return 0;
167    }
168
169  /* Fail if there are any open modules that use this loader.  */
170  iface = lt_dlinterface_register (id_string, NULL);
171  while ((handle = lt_dlhandle_iterate (iface, handle)))
172    {
173      lt_dlhandle cur = handle;
174      if (cur->vtable == vtable)
175        {
176          in_use = 1;
177          if (lt_dlisresident (handle))
178            in_use_by_resident = 1;
179        }
180    }
181  lt_dlinterface_free (iface);
182  if (in_use)
183    {
184      if (!in_use_by_resident)
185        LT__SETERROR (REMOVE_LOADER);
186      return 0;
187    }
188
189  /* Call the loader finalisation function.  */
190  if (vtable && vtable->dlloader_exit)
191    {
192      if ((*vtable->dlloader_exit) (vtable->dlloader_data) != 0)
193        {
194          /* If there is an exit function, and it returns non-zero
195             then it must set an error, and we will not remove it
196             from the list.  */
197          return 0;
198        }
199    }
200
201  /* If we got this far, remove the loader from our global list.  */
202  return (lt_dlvtable *)
203      slist_unbox ((SList *) slist_remove (&loaders, loader_callback, (void *) name));
204}
205
206
207const lt_dlvtable *
208lt_dlloader_find (const char *name)
209{
210  return lt_dlloader_get (slist_find (loaders, loader_callback, (void *) name));
211}
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