1 /* GMODULE - GLIB wrapper code for dynamic module loading
2 * Copyright (C) 1998, 2000 Tim Janik
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 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 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
16 */
17
18 /*
19 * Modified by the GLib Team and others 1997-2000. See the AUTHORS
20 * file for a list of people on the GLib Team. See the ChangeLog
21 * files for a list of changes. These files are distributed with
22 * GLib at ftp://ftp.gtk.org/pub/gtk/.
23 */
24
25 /*
26 * MT safe
27 */
28 #include "config.h"
29
30 #include <dlfcn.h>
31
32 /* Perl includes <nlist.h> and <link.h> instead of <dlfcn.h> on some systems? */
33
34
35 /* dlerror() is not implemented on all systems
36 */
37 #ifndef G_MODULE_HAVE_DLERROR
38 # ifdef __NetBSD__
39 # define dlerror() g_strerror (errno)
40 # else /* !__NetBSD__ */
41 /* could we rely on errno's state here? */
42 # define dlerror() "unknown dl-error"
43 # endif /* !__NetBSD__ */
44 #endif /* G_MODULE_HAVE_DLERROR */
45
46 /* some flags are missing on some systems, so we provide
47 * harmless defaults.
48 * The Perl sources say, RTLD_LAZY needs to be defined as (1),
49 * at least for Solaris 1.
50 *
51 * Mandatory:
52 * RTLD_LAZY - resolve undefined symbols as code from the dynamic library
53 * is executed.
54 * RTLD_NOW - resolve all undefined symbols before dlopen returns, and fail
55 * if this cannot be done.
56 * Optionally:
57 * RTLD_GLOBAL - the external symbols defined in the library will be made
58 * available to subsequently loaded libraries.
59 */
60 #ifndef HAVE_RTLD_LAZY
61 #define RTLD_LAZY 1
62 #endif /* RTLD_LAZY */
63 #ifndef HAVE_RTLD_NOW
64 #define RTLD_NOW 0
65 #endif /* RTLD_NOW */
66 /* some systems (OSF1 V5.0) have broken RTLD_GLOBAL linkage */
67 #ifdef G_MODULE_BROKEN_RTLD_GLOBAL
68 #undef RTLD_GLOBAL
69 #undef HAVE_RTLD_GLOBAL
70 #endif /* G_MODULE_BROKEN_RTLD_GLOBAL */
71 #ifndef HAVE_RTLD_GLOBAL
72 #define RTLD_GLOBAL 0
73 #endif /* RTLD_GLOBAL */
74
75
76 /* --- functions --- */
77 static gchar*
fetch_dlerror(gboolean replace_null)78 fetch_dlerror (gboolean replace_null)
79 {
80 gchar *msg = dlerror ();
81
82 /* make sure we always return an error message != NULL, if
83 * expected to do so. */
84
85 if (!msg && replace_null)
86 return "unknown dl-error";
87
88 return msg;
89 }
90
91 static gpointer
_g_module_open(const gchar * file_name,gboolean bind_lazy,gboolean bind_local)92 _g_module_open (const gchar *file_name,
93 gboolean bind_lazy,
94 gboolean bind_local)
95 {
96 gpointer handle;
97
98 handle = dlopen (file_name,
99 (bind_local ? 0 : RTLD_GLOBAL) | (bind_lazy ? RTLD_LAZY : RTLD_NOW));
100 if (!handle)
101 g_module_set_error (fetch_dlerror (TRUE));
102
103 return handle;
104 }
105
106 static gpointer
_g_module_self(void)107 _g_module_self (void)
108 {
109 gpointer handle;
110
111 /* to query symbols from the program itself, special link options
112 * are required on some systems.
113 */
114
115 /* On Android 32 bit (i.e. not __LP64__), dlopen(NULL)
116 * does not work reliable and generally no symbols are found
117 * at all. RTLD_DEFAULT works though.
118 * On Android 64 bit, dlopen(NULL) seems to work but dlsym(handle)
119 * always returns 'undefined symbol'. Only if RTLD_DEFAULT or
120 * NULL is given, dlsym returns an appropriate pointer.
121 */
122 #if defined(__BIONIC__)
123 handle = RTLD_DEFAULT;
124 #else
125 handle = dlopen (NULL, RTLD_GLOBAL | RTLD_LAZY);
126 #endif
127 if (!handle)
128 g_module_set_error (fetch_dlerror (TRUE));
129
130 return handle;
131 }
132
133 static void
_g_module_close(gpointer handle)134 _g_module_close (gpointer handle)
135 {
136 #if defined(__BIONIC__)
137 if (handle != RTLD_DEFAULT)
138 #endif
139 {
140 if (dlclose (handle) != 0)
141 g_module_set_error (fetch_dlerror (TRUE));
142 }
143 }
144
145 static gpointer
_g_module_symbol(gpointer handle,const gchar * symbol_name)146 _g_module_symbol (gpointer handle,
147 const gchar *symbol_name)
148 {
149 gpointer p;
150 gchar *msg;
151
152 fetch_dlerror (FALSE);
153 p = dlsym (handle, symbol_name);
154 msg = fetch_dlerror (FALSE);
155 if (msg)
156 g_module_set_error (msg);
157
158 return p;
159 }
160
161 static gchar*
_g_module_build_path(const gchar * directory,const gchar * module_name)162 _g_module_build_path (const gchar *directory,
163 const gchar *module_name)
164 {
165 if (directory && *directory) {
166 if (strncmp (module_name, "lib", 3) == 0)
167 return g_strconcat (directory, "/", module_name, NULL);
168 else
169 return g_strconcat (directory, "/lib", module_name, "." G_MODULE_SUFFIX, NULL);
170 } else if (strncmp (module_name, "lib", 3) == 0)
171 return g_strdup (module_name);
172 else
173 return g_strconcat ("lib", module_name, "." G_MODULE_SUFFIX, NULL);
174 }
175