mirror of https://gitee.com/openkylin/glib2.0.git
228 lines
6.2 KiB
C
228 lines
6.2 KiB
C
/* GMODULE - GLIB wrapper code for dynamic module loading
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* Copyright (C) 1998, 2000 Tim Janik
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*
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* SPDX-License-Identifier: LGPL-2.1-or-later
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* Modified by the GLib Team and others 1997-2000. See the AUTHORS
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* file for a list of people on the GLib Team. See the ChangeLog
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* files for a list of changes. These files are distributed with
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* GLib at ftp://ftp.gtk.org/pub/gtk/.
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*/
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/*
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* MT safe
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*/
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#include "config.h"
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#include <dlfcn.h>
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#include <glib.h>
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/* Perl includes <nlist.h> and <link.h> instead of <dlfcn.h> on some systems? */
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/* dlerror() is not implemented on all systems
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*/
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#ifndef G_MODULE_HAVE_DLERROR
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# ifdef __NetBSD__
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# define dlerror() g_strerror (errno)
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# else /* !__NetBSD__ */
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/* could we rely on errno's state here? */
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# define dlerror() "unknown dl-error"
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# endif /* !__NetBSD__ */
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#endif /* G_MODULE_HAVE_DLERROR */
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/* some flags are missing on some systems, so we provide
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* harmless defaults.
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* The Perl sources say, RTLD_LAZY needs to be defined as (1),
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* at least for Solaris 1.
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*
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* Mandatory:
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* RTLD_LAZY - resolve undefined symbols as code from the dynamic library
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* is executed.
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* RTLD_NOW - resolve all undefined symbols before dlopen returns, and fail
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* if this cannot be done.
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* Optionally:
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* RTLD_GLOBAL - the external symbols defined in the library will be made
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* available to subsequently loaded libraries.
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*/
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#ifndef HAVE_RTLD_LAZY
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#define RTLD_LAZY 1
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#endif /* RTLD_LAZY */
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#ifndef HAVE_RTLD_NOW
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#define RTLD_NOW 0
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#endif /* RTLD_NOW */
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/* some systems (OSF1 V5.0) have broken RTLD_GLOBAL linkage */
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#ifdef G_MODULE_BROKEN_RTLD_GLOBAL
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#undef RTLD_GLOBAL
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#undef HAVE_RTLD_GLOBAL
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#endif /* G_MODULE_BROKEN_RTLD_GLOBAL */
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#ifndef HAVE_RTLD_GLOBAL
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#define RTLD_GLOBAL 0
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#endif /* RTLD_GLOBAL */
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/* According to POSIX.1-2001, dlerror() is not necessarily thread-safe
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* (see https://pubs.opengroup.org/onlinepubs/009695399/), and so must be
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* called within the same locked section as the dlopen()/dlsym() call which
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* may have caused an error.
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*
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* However, some libc implementations, such as glibc, implement dlerror() using
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* thread-local storage, so are thread-safe. As of early 2021:
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* - glibc is thread-safe: https://github.com/bminor/glibc/blob/HEAD/dlfcn/libc_dlerror_result.c
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* - uclibc-ng is not thread-safe: https://cgit.uclibc-ng.org/cgi/cgit/uclibc-ng.git/tree/ldso/libdl/libdl.c?id=132decd2a043d0ccf799f42bf89f3ae0c11e95d5#n1075
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* - Other libc implementations have not been checked, and no problems have
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* been reported with them in 10 years, so default to assuming that they
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* don’t need additional thread-safety from GLib
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*/
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#if defined(__UCLIBC__)
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G_LOCK_DEFINE_STATIC (errors);
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#else
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#define DLERROR_IS_THREADSAFE 1
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#endif
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static void
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lock_dlerror (void)
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{
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#ifndef DLERROR_IS_THREADSAFE
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G_LOCK (errors);
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#endif
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}
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static void
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unlock_dlerror (void)
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{
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#ifndef DLERROR_IS_THREADSAFE
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G_UNLOCK (errors);
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#endif
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}
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/* This should be called with lock_dlerror() held */
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static const gchar *
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fetch_dlerror (gboolean replace_null)
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{
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const gchar *msg = dlerror ();
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/* make sure we always return an error message != NULL, if
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* expected to do so. */
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if (!msg && replace_null)
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return "unknown dl-error";
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return msg;
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}
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static gpointer
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_g_module_open (const gchar *file_name,
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gboolean bind_lazy,
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gboolean bind_local,
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GError **error)
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{
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gpointer handle;
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lock_dlerror ();
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handle = dlopen (file_name,
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(bind_local ? 0 : RTLD_GLOBAL) | (bind_lazy ? RTLD_LAZY : RTLD_NOW));
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if (!handle)
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{
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const gchar *message = fetch_dlerror (TRUE);
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g_module_set_error (message);
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g_set_error_literal (error, G_MODULE_ERROR, G_MODULE_ERROR_FAILED, message);
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}
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unlock_dlerror ();
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return handle;
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}
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static gpointer
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_g_module_self (void)
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{
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gpointer handle;
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/* to query symbols from the program itself, special link options
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* are required on some systems.
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*/
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/* On Android 32 bit (i.e. not __LP64__), dlopen(NULL)
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* does not work reliable and generally no symbols are found
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* at all. RTLD_DEFAULT works though.
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* On Android 64 bit, dlopen(NULL) seems to work but dlsym(handle)
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* always returns 'undefined symbol'. Only if RTLD_DEFAULT or
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* NULL is given, dlsym returns an appropriate pointer.
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*/
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lock_dlerror ();
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#if defined(__BIONIC__)
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handle = RTLD_DEFAULT;
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#else
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handle = dlopen (NULL, RTLD_GLOBAL | RTLD_LAZY);
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#endif
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if (!handle)
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g_module_set_error (fetch_dlerror (TRUE));
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unlock_dlerror ();
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return handle;
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}
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static void
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_g_module_close (gpointer handle)
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{
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#if defined(__BIONIC__)
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if (handle != RTLD_DEFAULT)
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#endif
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{
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lock_dlerror ();
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if (dlclose (handle) != 0)
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g_module_set_error (fetch_dlerror (TRUE));
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unlock_dlerror ();
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}
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}
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static gpointer
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_g_module_symbol (gpointer handle,
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const gchar *symbol_name)
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{
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gpointer p;
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const gchar *msg;
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lock_dlerror ();
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fetch_dlerror (FALSE);
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p = dlsym (handle, symbol_name);
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msg = fetch_dlerror (FALSE);
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if (msg)
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g_module_set_error (msg);
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unlock_dlerror ();
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return p;
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}
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static gchar*
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_g_module_build_path (const gchar *directory,
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const gchar *module_name)
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{
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if (directory && *directory) {
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if (strncmp (module_name, "lib", 3) == 0)
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return g_strconcat (directory, "/", module_name, NULL);
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else
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return g_strconcat (directory, "/lib", module_name, "." G_MODULE_SUFFIX, NULL);
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} else if (strncmp (module_name, "lib", 3) == 0)
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return g_strdup (module_name);
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else
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return g_strconcat ("lib", module_name, "." G_MODULE_SUFFIX, NULL);
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}
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