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
  31 #include <dl.h>
  32
  33
  34 /* some flags are missing on some systems, so we provide
  35  * harmless defaults.
  36  *
  37  * Mandatory:
  38  * BIND_IMMEDIATE  - Resolve symbol references when the library is loaded.
  39  * BIND_DEFERRED   - Delay code symbol resolution until actual reference.
  40  *
  41  * Optionally:
  42  * BIND_FIRST      - Place the library at the head of the symbol search order.
  43  * BIND_NONFATAL   - The default BIND_IMMEDIATE behavior is to treat all unsatisfied
  44  *                   symbols as fatal.  This flag allows binding of unsatisfied code
  45  *                   symbols to be deferred until use.
  46  *                   [Perl: For certain libraries, like DCE, deferred binding often
  47  *                   causes run time problems.  Adding BIND_NONFATAL to BIND_IMMEDIATE
  48  *                   still allows unresolved references in situations like this.]
  49  * BIND_NOSTART    - Do not call the initializer for the shared library when the
  50  *                   library is loaded, nor on a future call to shl_unload().
  51  * BIND_VERBOSE    - Print verbose messages concerning possible unsatisfied symbols.
  52  *
  53  * hp9000s700/hp9000s800:
  54  * BIND_RESTRICTED - Restrict symbols visible by the library to those present at
  55  *                   library load time.
  56  * DYNAMIC_PATH    - Allow the loader to dynamically search for the library specified
  57  *                   by the path argument.
  58  */
  59 #ifndef DYNAMIC_PATH
  60 #define DYNAMIC_PATH    0
  61 #endif  /* DYNAMIC_PATH */
  62 #ifndef BIND_RESTRICTED
  63 #define BIND_RESTRICTED 0
  64 #endif  /* BIND_RESTRICTED */
  65
  66 #define OPT_BIND_FLAGS  (BIND_NONFATAL | BIND_VERBOSE)
  67
  68
  69 /* --- functions --- */
  70
  71 /*
  72  * shl_load() does not appear to support making symbols invisible to
  73  * the global namespace.  However, the default is to put the library
  74  * last in the search order, which is approximately what we want,
  75  * since it will cause symbols that conflict with existing symbols to
  76  * be invisible.  It is unclear if BIND_FIRST should be used when
  77  * bind_local==0, since it may cause the loaded symbols to be used
  78  * preferentially to the application's symbols, which is Almost
  79  * Always Wrong.  --ds
  80  */
  81 static gpointer
  82 _g_module_open (const gchar *file_name,
  83                 gboolean     bind_lazy,
  84                 gboolean     bind_local)
  85 {
  86   shl_t shl_handle;
  87
  88   shl_handle = shl_load (file_name,
  89                          (bind_lazy ? BIND_DEFERRED : BIND_IMMEDIATE) | OPT_BIND_FLAGS, 0);
  90   if (!shl_handle)
  91     {
  92       /* the hp-docs say we should better abort() if errno==ENOSYM ;( */
  93       g_module_set_error (g_strerror (errno));
  94     }
  95
  96   return (gpointer) shl_handle;
  97 }
  98
  99 static gpointer
 100 _g_module_self (void)
 101 {
 102   shl_t shl_handle;
 103
 104   shl_handle = PROG_HANDLE;
 105   if (!shl_handle)
 106     g_module_set_error (g_strerror (errno));
 107
 108   return shl_handle;
 109 }
 110
 111 static void
 112 _g_module_close (gpointer handle,
 113                  gboolean is_unref)
 114 {
 115   if (!is_unref)
 116     {
 117       if (shl_unload ((shl_t) handle) != 0)
 118         g_module_set_error (g_strerror (errno));
 119     }
 120 }
 121
 122 static gpointer
 123 _g_module_symbol (gpointer     handle,
 124                   const gchar *symbol_name)
 125 {
 126   gpointer p = NULL;
 127
 128   /* should we restrict lookups to TYPE_PROCEDURE?
 129    */
 130   if (handle == PROG_HANDLE)
 131     {
 132       /* PROG_HANDLE will only lookup symbols in the program itself, not honouring
 133        * libraries. passing NULL as a handle will also try to lookup the symbol
 134        * in currently loaded libraries. fix pointed out and supplied by:
 135        * David Gero <dgero@nortelnetworks.com>
 136        */
 137       handle = NULL;
 138     }
 139   if (shl_findsym ((shl_t*) &handle, symbol_name, TYPE_UNDEFINED, &p) != 0 ||
 140       handle == NULL || p == NULL)
 141     {
 142       /* the hp-docs say we should better abort() if errno==ENOSYM ;( */
 143       g_module_set_error (g_strerror (errno));
 144     }
 145
 146   return p;
 147 }
 148
 149 static gchar*
 150 _g_module_build_path (const gchar *directory,
 151                       const gchar *module_name)
 152 {
 153   if (directory && *directory)
 154     if (strncmp (module_name, "lib", 3) == 0)
 155       return g_strconcat (directory, "/", module_name, NULL);
 156     else
 157       return g_strconcat (directory, "/lib", module_name, ".sl", NULL);
 158   else if (strncmp (module_name, "lib", 3) == 0)
 159     return g_strdup (module_name);
 160   else
 161     return g_strconcat ("lib", module_name, ".sl", NULL);
 162 }