gmodule/gmodule-dl.c

   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 }