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

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

Initial release

File size: 6.2 KB
Line 
1/* loader-dlopen.c --  dynamic linking with dlopen/dlsym
2
3   Copyright (C) 1998, 1999, 2000, 2004, 2006,
4                 2007, 2008 Free Software Foundation, Inc.
5   Written by Thomas Tanner, 1998
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/* Use the preprocessor to rename non-static symbols to avoid namespace
36   collisions when the loader code is statically linked into libltdl.
37   Use the "<module_name>_LTX_" prefix so that the symbol addresses can
38   be fetched from the preloaded symbol list by lt_dlsym():  */
39#define get_vtable      dlopen_LTX_get_vtable
40
41LT_BEGIN_C_DECLS
42LT_SCOPE lt_dlvtable *get_vtable (lt_user_data loader_data);
43LT_END_C_DECLS
44
45
46/* Boilerplate code to set up the vtable for hooking this loader into
47   libltdl's loader list:  */
48static int       vl_exit  (lt_user_data loader_data);
49static lt_module vm_open  (lt_user_data loader_data, const char *filename,
50                           lt_dladvise advise);
51static int       vm_close (lt_user_data loader_data, lt_module module);
52static void *    vm_sym   (lt_user_data loader_data, lt_module module,
53                          const char *symbolname);
54
55static lt_dlvtable *vtable = 0;
56
57/* Return the vtable for this loader, only the name and sym_prefix
58   attributes (plus the virtual function implementations, obviously)
59   change between loaders.  */
60lt_dlvtable *
61get_vtable (lt_user_data loader_data)
62{
63  if (!vtable)
64    {
65      vtable = (lt_dlvtable *) lt__zalloc (sizeof *vtable);
66    }
67
68  if (vtable && !vtable->name)
69    {
70      vtable->name              = "lt_dlopen";
71#if defined(DLSYM_USCORE)
72      vtable->sym_prefix        = "_";
73#endif
74      vtable->module_open       = vm_open;
75      vtable->module_close      = vm_close;
76      vtable->find_sym          = vm_sym;
77      vtable->dlloader_exit     = vl_exit;
78      vtable->dlloader_data     = loader_data;
79      vtable->priority          = LT_DLLOADER_PREPEND;
80    }
81
82  if (vtable && (vtable->dlloader_data != loader_data))
83    {
84      LT__SETERROR (INIT_LOADER);
85      return 0;
86    }
87
88  return vtable;
89}
90
91
92
93/* --- IMPLEMENTATION --- */
94
95
96#if defined(HAVE_DLFCN_H)
97#  include <dlfcn.h>
98#endif
99
100#if defined(HAVE_SYS_DL_H)
101#  include <sys/dl.h>
102#endif
103
104
105/* We may have to define LT_LAZY_OR_NOW in the command line if we
106   find out it does not work in some platform. */
107#if !defined(LT_LAZY_OR_NOW)
108#  if defined(RTLD_LAZY)
109#    define LT_LAZY_OR_NOW      RTLD_LAZY
110#  else
111#    if defined(DL_LAZY)
112#      define LT_LAZY_OR_NOW    DL_LAZY
113#    endif
114#  endif /* !RTLD_LAZY */
115#endif
116#if !defined(LT_LAZY_OR_NOW)
117#  if defined(RTLD_NOW)
118#    define LT_LAZY_OR_NOW      RTLD_NOW
119#  else
120#    if defined(DL_NOW)
121#      define LT_LAZY_OR_NOW    DL_NOW
122#    endif
123#  endif /* !RTLD_NOW */
124#endif
125#if !defined(LT_LAZY_OR_NOW)
126#  define LT_LAZY_OR_NOW        0
127#endif /* !LT_LAZY_OR_NOW */
128
129/* We only support local and global symbols from modules for loaders
130   that provide such a thing, otherwise the system default is used.  */
131#if !defined(RTLD_GLOBAL)
132#  if defined(DL_GLOBAL)
133#    define RTLD_GLOBAL         DL_GLOBAL
134#  endif
135#endif /* !RTLD_GLOBAL */
136#if !defined(RTLD_LOCAL)
137#  if defined(DL_LOCAL)
138#    define RTLD_LOCAL          DL_LOCAL
139#  endif
140#endif /* !RTLD_LOCAL */
141
142#if defined(HAVE_DLERROR)
143#  define DLERROR(arg)  dlerror ()
144#else
145#  define DLERROR(arg)  LT__STRERROR (arg)
146#endif
147
148#define DL__SETERROR(errorcode) \
149        LT__SETERRORSTR (DLERROR (errorcode))
150
151
152/* A function called through the vtable when this loader is no
153   longer needed by the application.  */
154static int
155vl_exit (lt_user_data LT__UNUSED loader_data)
156{
157  vtable = NULL;
158  return 0;
159}
160
161
162/* A function called through the vtable to open a module with this
163   loader.  Returns an opaque representation of the newly opened
164   module for processing with this loader's other vtable functions.  */
165static lt_module
166vm_open (lt_user_data LT__UNUSED loader_data, const char *filename,
167         lt_dladvise advise)
168{
169  int           module_flags = LT_LAZY_OR_NOW;
170  lt_module     module;
171
172  if (advise)
173    {
174#ifdef RTLD_GLOBAL
175      /* If there is some means of asking for global symbol resolution,
176         do so.  */
177      if (advise->is_symglobal)
178        module_flags |= RTLD_GLOBAL;
179#else
180      /* Otherwise, reset that bit so the caller can tell it wasn't
181         acted on.  */
182      advise->is_symglobal = 0;
183#endif
184
185/* And similarly for local only symbol resolution.  */
186#ifdef RTLD_LOCAL
187      if (advise->is_symlocal)
188        module_flags |= RTLD_LOCAL;
189#else
190      advise->is_symlocal = 0;
191#endif
192    }
193
194  module = dlopen (filename, module_flags);
195
196  if (!module)
197    {
198      DL__SETERROR (CANNOT_OPEN);
199    }
200
201  return module;
202}
203
204
205/* A function called through the vtable when a particular module
206   should be unloaded.  */
207static int
208vm_close (lt_user_data LT__UNUSED loader_data, lt_module module)
209{
210  int errors = 0;
211
212  if (dlclose (module) != 0)
213    {
214      DL__SETERROR (CANNOT_CLOSE);
215      ++errors;
216    }
217
218  return errors;
219}
220
221
222/* A function called through the vtable to get the address of
223   a symbol loaded from a particular module.  */
224static void *
225vm_sym (lt_user_data LT__UNUSED loader_data, lt_module module, const char *name)
226{
227  void *address = dlsym (module, name);
228
229  if (!address)
230    {
231      DL__SETERROR (SYMBOL_NOT_FOUND);
232    }
233
234  return address;
235}
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