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      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 --- */
     78 static gchar*
     79 fetch_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 
     92 static 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 
    107 static 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 
    123 static 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 
    139 static 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 
    155 static 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