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, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 /*
  19  * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
  20  * file for a list of people on the GLib Team.  See the ChangeLog
  21  * files for a list of changes.  These files are distributed with
  22  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  23  */
  24
  25 /*
  26  * MT safe
  27  */
  28 #include "config.h"
  29
  30 #include <dlfcn.h>
  31
  32 /* Perl includes <nlist.h> and <link.h> instead of <dlfcn.h> on some systmes? */
  33
  34
  35 /* dlerror() is not implemented on all systems
  36  */
  37 #ifndef G_MODULE_HAVE_DLERROR
  38 #  ifdef __NetBSD__
  39 #    define dlerror()   g_strerror (errno)
  40 #  else /* !__NetBSD__ */
  41 /* could we rely on errno's state here? */
  42 #    define dlerror()   "unknown dl-error"
  43 #  endif /* !__NetBSD__ */
  44 #endif  /* G_MODULE_HAVE_DLERROR */
  45
  46 /* some flags are missing on some systems, so we provide
  47  * harmless defaults.
  48  * The Perl sources say, RTLD_LAZY needs to be defined as (1),
  49  * at least for Solaris 1.
  50  *
  51  * Mandatory:
  52  * RTLD_LAZY   - resolve undefined symbols as code from the dynamic library
  53  *               is executed.
  54  * RTLD_NOW    - resolve all undefined symbols before dlopen returns, and fail
  55  *               if this cannot be done.
  56  * Optionally:
  57  * RTLD_GLOBAL - the external symbols defined in the library will be made
  58  *               available to subsequently loaded libraries.
  59  */
  60 #ifndef RTLD_LAZY
  61 #define RTLD_LAZY       1
  62 #endif  /* RTLD_LAZY */
  63 #ifndef RTLD_NOW
  64 #define RTLD_NOW        0
  65 #endif  /* RTLD_NOW */
  66 /* some systems (OSF1 V5.0) have broken RTLD_GLOBAL linkage */
  67 #ifdef G_MODULE_BROKEN_RTLD_GLOBAL
  68 #undef  RTLD_GLOBAL
  69 #endif /* G_MODULE_BROKEN_RTLD_GLOBAL */
  70 #ifndef RTLD_GLOBAL
  71 #define RTLD_GLOBAL     0
  72 #endif  /* RTLD_GLOBAL */
  73
  74
  75 /* --- functions --- */
  76 static gchar*
  77 fetch_dlerror (gboolean replace_null)
  78 {
  79   gchar *msg = dlerror ();
  80
  81   /* make sure we always return an error message != NULL, if
  82    * expected to do so. */
  83
  84   if (!msg && replace_null)
  85     return "unknown dl-error";
  86
  87   return msg;
  88 }
  89
  90 static gpointer
  91 _g_module_open (const gchar *file_name,
  92                 gboolean     bind_lazy,
  93                 gboolean     bind_local)
  94 {
  95   gpointer handle;
  96
  97   handle = dlopen (file_name,
  98                    (bind_local ? 0 : RTLD_GLOBAL) | (bind_lazy ? RTLD_LAZY : RTLD_NOW));
  99   if (!handle)
 100     g_module_set_error (fetch_dlerror (TRUE));
 101
 102   return handle;
 103 }
 104
 105 static gpointer
 106 _g_module_self (void)
 107 {
 108   gpointer handle;
 109
 110   /* to query symbols from the program itself, special link options
 111    * are required on some systems.
 112    */
 113
 114 #ifdef __BIONIC__
 115   handle = RTLD_DEFAULT;
 116 #else
 117   handle = dlopen (NULL, RTLD_GLOBAL | RTLD_LAZY);
 118 #endif
 119   if (!handle)
 120     g_module_set_error (fetch_dlerror (TRUE));
 121
 122   return handle;
 123 }
 124
 125 static void
 126 _g_module_close (gpointer handle,
 127                  gboolean is_unref)
 128 {
 129   /* are there any systems out there that have dlopen()/dlclose()
 130    * without a reference count implementation?
 131    */
 132   is_unref |= 1;
 133
 134   if (is_unref)
 135     {
 136       if (dlclose (handle) != 0)
 137         g_module_set_error (fetch_dlerror (TRUE));
 138     }
 139 }
 140
 141 static gpointer
 142 _g_module_symbol (gpointer     handle,
 143                   const gchar *symbol_name)
 144 {
 145   gpointer p;
 146   gchar *msg;
 147
 148   fetch_dlerror (FALSE);
 149   p = dlsym (handle, symbol_name);
 150   msg = fetch_dlerror (FALSE);
 151   if (msg)
 152     g_module_set_error (msg);
 153
 154   return p;
 155 }
 156
 157 static gchar*
 158 _g_module_build_path (const gchar *directory,
 159                       const gchar *module_name)
 160 {
 161   if (directory && *directory) {
 162     if (strncmp (module_name, "lib", 3) == 0)
 163       return g_strconcat (directory, "/", module_name, NULL);
 164     else
 165       return g_strconcat (directory, "/lib", module_name, "." G_MODULE_SUFFIX, NULL);
 166   } else if (strncmp (module_name, "lib", 3) == 0)
 167     return g_strdup (module_name);
 168   else
 169     return g_strconcat ("lib", module_name, "." G_MODULE_SUFFIX, NULL);
 170 }