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
  31 #include <dlfcn.h>
  32
  33 /* Perl includes <nlist.h> and <link.h> instead of <dlfcn.h> on some systmes? */
  34
  35
  36 /* dlerror() is not implemented on all systems
  37  */
  38 #ifndef G_MODULE_HAVE_DLERROR
  39 #  ifdef __NetBSD__
  40 #    define dlerror()   g_strerror (errno)
  41 #  else /* !__NetBSD__ */
  42 /* could we rely on errno's state here? */
  43 #    define dlerror()   "unknown dl-error"
  44 #  endif /* !__NetBSD__ */
  45 #endif  /* G_MODULE_HAVE_DLERROR */
  46
  47 /* some flags are missing on some systems, so we provide
  48  * harmless defaults.
  49  * The Perl sources say, RTLD_LAZY needs to be defined as (1),
  50  * at least for Solaris 1.
  51  *
  52  * Mandatory:
  53  * RTLD_LAZY   - resolve undefined symbols as code from the dynamic library
  54  *               is executed.
  55  * RTLD_NOW    - resolve all undefined symbols before dlopen returns, and fail
  56  *               if this cannot be done.
  57  * Optionally:
  58  * RTLD_GLOBAL - the external symbols defined in the library will be made
  59  *               available to subsequently loaded libraries.
  60  */
  61 #ifndef RTLD_LAZY
  62 #define RTLD_LAZY       1
  63 #endif  /* RTLD_LAZY */
  64 #ifndef RTLD_NOW
  65 #define RTLD_NOW        0
  66 #endif  /* RTLD_NOW */
  67 /* some systems (OSF1 V5.0) have broken RTLD_GLOBAL linkage */
  68 #ifdef G_MODULE_BROKEN_RTLD_GLOBAL
  69 #undef  RTLD_GLOBAL
  70 #endif /* G_MODULE_BROKEN_RTLD_GLOBAL */
  71 #ifndef RTLD_GLOBAL
  72 #define RTLD_GLOBAL     0
  73 #endif  /* RTLD_GLOBAL */
  74
  75
  76 /* --- functions --- */
  77 static gchar*
  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
  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
 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   handle = dlopen (NULL, RTLD_GLOBAL | RTLD_LAZY);
 116   if (!handle)
 117     g_module_set_error (fetch_dlerror (TRUE));
 118
 119   return handle;
 120 }
 121
 122 static void
 123 _g_module_close (gpointer handle,
 124                  gboolean is_unref)
 125 {
 126   /* are there any systems out there that have dlopen()/dlclose()
 127    * without a reference count implementation?
 128    */
 129   is_unref |= 1;
 130
 131   if (is_unref)
 132     {
 133       if (dlclose (handle) != 0)
 134         g_module_set_error (fetch_dlerror (TRUE));
 135     }
 136 }
 137
 138 static gpointer
 139 _g_module_symbol (gpointer     handle,
 140                   const gchar *symbol_name)
 141 {
 142   gpointer p;
 143   gchar *msg;
 144
 145   fetch_dlerror (FALSE);
 146   p = dlsym (handle, symbol_name);
 147   msg = fetch_dlerror (FALSE);
 148   if (msg)
 149     g_module_set_error (msg);
 150
 151   return p;
 152 }
 153
 154 static gchar*
 155 _g_module_build_path (const gchar *directory,
 156                       const gchar *module_name)
 157 {
 158   if (directory && *directory) {
 159     if (strncmp (module_name, "lib", 3) == 0)
 160       return g_strconcat (directory, "/", module_name, NULL);
 161     else
 162       return g_strconcat (directory, "/lib", module_name, "." G_MODULE_SUFFIX, NULL);
 163   } else if (strncmp (module_name, "lib", 3) == 0)
 164     return g_strdup (module_name);
 165   else
 166     return g_strconcat ("lib", module_name, "." G_MODULE_SUFFIX, NULL);
 167 }