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 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, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
18 */
19
20/*
21 * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
22 * file for a list of people on the GLib Team.  See the ChangeLog
23 * files for a list of changes.  These files are distributed with
24 * GLib at ftp://ftp.gtk.org/pub/gtk/.
25 */
26
27/*
28 * MT safe
29 */
30#include "config.h"
31
32#include <dlfcn.h>
33
34/* Perl includes <nlist.h> and <link.h> instead of <dlfcn.h> on some systmes? */
35
36
37/* dlerror() is not implemented on all systems
38 */
39#ifndef	G_MODULE_HAVE_DLERROR
40#  ifdef __NetBSD__
41#    define dlerror()	g_strerror (errno)
42#  else /* !__NetBSD__ */
43/* could we rely on errno's state here? */
44#    define dlerror()	"unknown dl-error"
45#  endif /* !__NetBSD__ */
46#endif	/* G_MODULE_HAVE_DLERROR */
47
48/* some flags are missing on some systems, so we provide
49 * harmless defaults.
50 * The Perl sources say, RTLD_LAZY needs to be defined as (1),
51 * at least for Solaris 1.
52 *
53 * Mandatory:
54 * RTLD_LAZY   - resolve undefined symbols as code from the dynamic library
55 *		 is executed.
56 * RTLD_NOW    - resolve all undefined symbols before dlopen returns, and fail
57 *		 if this cannot be done.
58 * Optionally:
59 * RTLD_GLOBAL - the external symbols defined in the library will be made
60 *		 available to subsequently loaded libraries.
61 */
62#ifndef	RTLD_LAZY
63#define	RTLD_LAZY	1
64#endif	/* RTLD_LAZY */
65#ifndef	RTLD_NOW
66#define	RTLD_NOW	0
67#endif	/* RTLD_NOW */
68/* some systems (OSF1 V5.0) have broken RTLD_GLOBAL linkage */
69#ifdef G_MODULE_BROKEN_RTLD_GLOBAL
70#undef	RTLD_GLOBAL
71#endif /* G_MODULE_BROKEN_RTLD_GLOBAL */
72#ifndef	RTLD_GLOBAL
73#define	RTLD_GLOBAL	0
74#endif	/* RTLD_GLOBAL */
75
76
77/* --- functions --- */
78static gchar*
79fetch_dlerror (gboolean replace_null)
80{
81  gchar *msg = dlerror ();
82
83  /* make sure we always return an error message != NULL, if
84   * expected to do so. */
85
86  if (!msg && replace_null)
87    return "unknown dl-error";
88
89  return msg;
90}
91
92static gpointer
93_g_module_open (const gchar *file_name,
94		gboolean     bind_lazy,
95		gboolean     bind_local)
96{
97  gpointer handle;
98
99  handle = dlopen (file_name,
100		   (bind_local ? 0 : RTLD_GLOBAL) | (bind_lazy ? RTLD_LAZY : RTLD_NOW));
101  if (!handle)
102    g_module_set_error (fetch_dlerror (TRUE));
103
104  return handle;
105}
106
107static gpointer
108_g_module_self (void)
109{
110  gpointer handle;
111
112  /* to query symbols from the program itself, special link options
113   * are required on some systems.
114   */
115
116  handle = dlopen (NULL, RTLD_GLOBAL | RTLD_LAZY);
117  if (!handle)
118    g_module_set_error (fetch_dlerror (TRUE));
119
120  return handle;
121}
122
123static void
124_g_module_close (gpointer handle,
125		 gboolean is_unref)
126{
127  /* are there any systems out there that have dlopen()/dlclose()
128   * without a reference count implementation?
129   */
130  is_unref |= 1;
131
132  if (is_unref)
133    {
134      if (dlclose (handle) != 0)
135	g_module_set_error (fetch_dlerror (TRUE));
136    }
137}
138
139static gpointer
140_g_module_symbol (gpointer     handle,
141		  const gchar *symbol_name)
142{
143  gpointer p;
144  gchar *msg;
145
146  fetch_dlerror (FALSE);
147  p = dlsym (handle, symbol_name);
148  msg = fetch_dlerror (FALSE);
149  if (msg)
150    g_module_set_error (msg);
151
152  return p;
153}
154
155static gchar*
156_g_module_build_path (const gchar *directory,
157		      const gchar *module_name)
158{
159  if (directory && *directory) {
160    if (strncmp (module_name, "lib", 3) == 0)
161      return g_strconcat (directory, "/", module_name, NULL);
162    else
163      return g_strconcat (directory, "/lib", module_name, "." G_MODULE_SUFFIX, NULL);
164  } else if (strncmp (module_name, "lib", 3) == 0)
165    return g_strdup (module_name);
166  else
167    return g_strconcat ("lib", module_name, "." G_MODULE_SUFFIX, NULL);
168}
169