release/src/router/glib/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 Library 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  * Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library 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 1997-1999.  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 (void)
  79 {
  80   gchar *msg = dlerror ();
  81
  82   /* make sure we always return an error message != NULL */
  83
  84   return msg ? msg : "unknown dl-error";
  85 }
  86
  87 static gpointer
  88 _g_module_open (const gchar *file_name,
  89                 gboolean     bind_lazy)
  90 {
  91   gpointer handle;
  92
  93   handle = dlopen (file_name, RTLD_GLOBAL | (bind_lazy ? RTLD_LAZY : RTLD_NOW));
  94   if (!handle)
  95     g_module_set_error (fetch_dlerror ());
  96
  97   return handle;
  98 }
  99
 100 static gpointer
 101 _g_module_self (void)
 102 {
 103   gpointer handle;
 104
 105   /* to query symbols from the program itself, special link options
 106    * are required on some systems.
 107    */
 108
 109   handle = dlopen (NULL, RTLD_GLOBAL | RTLD_LAZY);
 110   if (!handle)
 111     g_module_set_error (fetch_dlerror ());
 112
 113   return handle;
 114 }
 115
 116 static void
 117 _g_module_close (gpointer handle,
 118                  gboolean is_unref)
 119 {
 120   /* are there any systems out there that have dlopen()/dlclose()
 121    * without a reference count implementation?
 122    */
 123   is_unref |= 1;
 124
 125   if (is_unref)
 126     {
 127       if (dlclose (handle) != 0)
 128         g_module_set_error (fetch_dlerror ());
 129     }
 130 }
 131
 132 static gpointer
 133 _g_module_symbol (gpointer     handle,
 134                   const gchar *symbol_name)
 135 {
 136   gpointer p;
 137
 138   p = dlsym (handle, symbol_name);
 139   if (!p)
 140     g_module_set_error (fetch_dlerror ());
 141
 142   return p;
 143 }
 144
 145 static gchar*
 146 _g_module_build_path (const gchar *directory,
 147                       const gchar *module_name)
 148 {
 149   if (directory && *directory) {
 150     if (strncmp (module_name, "lib", 3) == 0)
 151       return g_strconcat (directory, "/", module_name, NULL);
 152     else
 153       return g_strconcat (directory, "/lib", module_name, ".so", NULL);
 154   } else if (strncmp (module_name, "lib", 3) == 0)
 155     return g_strdup (module_name);
 156   else
 157     return g_strconcat ("lib", module_name, ".so", NULL);
 158 }