gmodule/gmodule-dld.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 <dl.h>
  33
  34
  35 /* some flags are missing on some systems, so we provide
  36  * harmless defaults.
  37  *
  38  * Mandatory:
  39  * BIND_IMMEDIATE  - Resolve symbol references when the library is loaded.
  40  * BIND_DEFERRED   - Delay code symbol resolution until actual reference.
  41  *
  42  * Optionally:
  43  * BIND_FIRST      - Place the library at the head of the symbol search order.
  44  * BIND_NONFATAL   - The default BIND_IMMEDIATE behavior is to treat all unsatisfied
  45  *                   symbols as fatal.  This flag allows binding of unsatisfied code
  46  *                   symbols to be deferred until use.
  47  *                   [Perl: For certain libraries, like DCE, deferred binding often
  48  *                   causes run time problems.  Adding BIND_NONFATAL to BIND_IMMEDIATE
  49  *                   still allows unresolved references in situations like this.]
  50  * BIND_NOSTART    - Do not call the initializer for the shared library when the
  51  *                   library is loaded, nor on a future call to shl_unload().
  52  * BIND_VERBOSE    - Print verbose messages concerning possible unsatisfied symbols.
  53  *
  54  * hp9000s700/hp9000s800:
  55  * BIND_RESTRICTED - Restrict symbols visible by the library to those present at
  56  *                   library load time.
  57  * DYNAMIC_PATH    - Allow the loader to dynamically search for the library specified
  58  *                   by the path argument.
  59  */
  60 #ifndef DYNAMIC_PATH
  61 #define DYNAMIC_PATH    0
  62 #endif  /* DYNAMIC_PATH */
  63 #ifndef BIND_RESTRICTED
  64 #define BIND_RESTRICTED 0
  65 #endif  /* BIND_RESTRICTED */
  66
  67 #define OPT_BIND_FLAGS  (BIND_NONFATAL | BIND_VERBOSE)
  68
  69
  70 /* --- functions --- */
  71
  72 /*
  73  * shl_load() does not appear to support making symbols invisible to
  74  * the global namespace.  However, the default is to put the library
  75  * last in the search order, which is approximately what we want,
  76  * since it will cause symbols that conflict with existing symbols to
  77  * be invisible.  It is unclear if BIND_FIRST should be used when
  78  * bind_local==0, since it may cause the loaded symbols to be used
  79  * preferentially to the application's symbols, which is Almost
  80  * Always Wrong.  --ds
  81  */
  82 static gpointer
  83 _g_module_open (const gchar *file_name,
  84                 gboolean     bind_lazy,
  85                 gboolean     bind_local)
  86 {
  87   shl_t shl_handle;
  88
  89   shl_handle = shl_load (file_name,
  90                          (bind_lazy ? BIND_DEFERRED : BIND_IMMEDIATE) | OPT_BIND_FLAGS, 0);
  91   if (!shl_handle)
  92     {
  93       /* the hp-docs say we should better abort() if errno==ENOSYM ;( */
  94       g_module_set_error (g_strerror (errno));
  95     }
  96
  97   return (gpointer) shl_handle;
  98 }
  99
 100 static gpointer
 101 _g_module_self (void)
 102 {
 103   shl_t shl_handle;
 104
 105   shl_handle = PROG_HANDLE;
 106   if (!shl_handle)
 107     g_module_set_error (g_strerror (errno));
 108
 109   return shl_handle;
 110 }
 111
 112 static void
 113 _g_module_close (gpointer handle,
 114                  gboolean is_unref)
 115 {
 116   if (!is_unref)
 117     {
 118       if (shl_unload ((shl_t) handle) != 0)
 119         g_module_set_error (g_strerror (errno));
 120     }
 121 }
 122
 123 static gpointer
 124 _g_module_symbol (gpointer     handle,
 125                   const gchar *symbol_name)
 126 {
 127   gpointer p = NULL;
 128
 129   /* should we restrict lookups to TYPE_PROCEDURE?
 130    */
 131   if (handle == PROG_HANDLE)
 132     {
 133       /* PROG_HANDLE will only lookup symbols in the program itself, not honouring
 134        * libraries. passing NULL as a handle will also try to lookup the symbol
 135        * in currently loaded libraries. fix pointed out and supplied by:
 136        * David Gero <dgero@nortelnetworks.com>
 137        */
 138       handle = NULL;
 139     }
 140   if (shl_findsym ((shl_t*) &handle, symbol_name, TYPE_UNDEFINED, &p) != 0 ||
 141       handle == NULL || p == NULL)
 142     {
 143       /* the hp-docs say we should better abort() if errno==ENOSYM ;( */
 144       g_module_set_error (g_strerror (errno));
 145     }
 146
 147   return p;
 148 }
 149
 150 static gchar*
 151 _g_module_build_path (const gchar *directory,
 152                       const gchar *module_name)
 153 {
 154   if (directory && *directory)
 155     if (strncmp (module_name, "lib", 3) == 0)
 156       return g_strconcat (directory, "/", module_name, NULL);
 157     else
 158       return g_strconcat (directory, "/lib", module_name, ".sl", NULL);
 159   else if (strncmp (module_name, "lib", 3) == 0)
 160     return g_strdup (module_name);
 161   else
 162     return g_strconcat ("lib", module_name, ".sl", NULL);
 163 }