root/libltdl/lt_dlloader.c

/* */

DEFINITIONS

1. loader_callback
2. lt_dlloader_add
3. loader_dump_callback
4. lt_dlloader_dump
5. lt_dlloader_next
6. lt_dlloader_get
7. lt_dlloader_remove
8. lt_dlloader_find

   1 /* lt_dlloader.c -- dynamic library loader interface
   2 
   3    Copyright (C) 2004, 2007, 2008 Free Software Foundation, Inc.
   4    Written by Gary V. Vaughan, 2004
   5 
   6    NOTE: The canonical source of this file is maintained with the
   7    GNU Libtool package.  Report bugs to bug-libtool@gnu.org.
   8 
   9 GNU Libltdl is free software; you can redistribute it and/or
  10 modify it under the terms of the GNU Lesser General Public
  11 License as published by the Free Software Foundation; either
  12 version 2 of the License, or (at your option) any later version.
  13 
  14 As a special exception to the GNU Lesser General Public License,
  15 if you distribute this file as part of a program or library that
  16 is built using GNU Libtool, you may include this file under the
  17 same distribution terms that you use for the rest of that program.
  18 
  19 GNU Libltdl is distributed in the hope that it will be useful,
  20 but WITHOUT ANY WARRANTY; without even the implied warranty of
  21 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22 GNU Lesser General Public License for more details.
  23 
  24 You should have received a copy of the GNU Lesser General Public
  25 License along with GNU Libltdl; see the file COPYING.LIB.  If not, a
  26 copy can be downloaded from  http://www.gnu.org/licenses/lgpl.html,
  27 or obtained by writing to the Free Software Foundation, Inc.,
  28 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  29 */
  30 
  31 #include "lt__private.h"
  32 #include "lt_dlloader.h"
  33 
  34 #define RETURN_SUCCESS 0
  35 #define RETURN_FAILURE 1
  36 
  37 static void *   loader_callback (SList *item, void *userdata);
  38 
  39 /* A list of all the dlloaders we know about, each stored as a boxed
  40    SList item:  */
  41 static  SList    *loaders               = 0;
  42 
  43 
  44 /* Return NULL, unless the loader in this ITEM has a matching name,
  45    in which case we return the matching item so that its address is
  46    passed back out (for possible freeing) by slist_remove.  */
  47 static void *
  48 loader_callback (SList *item, void *userdata)
  49 {
  50   const lt_dlvtable *vtable = (const lt_dlvtable *) item->userdata;
  51   const char *      name    = (const char *) userdata;
  52 
  53   assert (vtable);
  54 
  55   return streq (vtable->name, name) ? (void *) item : NULL;
  56 }
  57 
  58 
  59 /* Hook VTABLE into our global LOADERS list according to its own
  60    PRIORITY field value.  */
  61 int
  62 lt_dlloader_add (const lt_dlvtable *vtable)
  63 {
  64   SList *item;
  65 
  66   if ((vtable == 0)     /* diagnose invalid vtable fields */
  67       || (vtable->module_open == 0)
  68       || (vtable->module_close == 0)
  69       || (vtable->find_sym == 0)
  70       || ((vtable->priority != LT_DLLOADER_PREPEND) &&
  71           (vtable->priority != LT_DLLOADER_APPEND)))
  72     {
  73       LT__SETERROR (INVALID_LOADER);
  74       return RETURN_FAILURE;
  75     }
  76 
  77   item = slist_box (vtable);
  78   if (!item)
  79     {
  80       (*lt__alloc_die) ();
  81 
  82       /* Let the caller know something went wrong if lt__alloc_die
  83          doesn't abort.  */
  84       return RETURN_FAILURE;
  85     }
  86 
  87   if (vtable->priority == LT_DLLOADER_PREPEND)
  88     {
  89       loaders = slist_cons (item, loaders);
  90     }
  91   else
  92     {
  93       assert (vtable->priority == LT_DLLOADER_APPEND);
  94       loaders = slist_concat (loaders, item);
  95     }
  96 
  97   return RETURN_SUCCESS;
  98 }
  99 
 100 #ifdef LT_DEBUG_LOADERS
 101 static void *
 102 loader_dump_callback (SList *item, void *userdata)
 103 {
 104   const lt_dlvtable *vtable = (const lt_dlvtable *) item->userdata;
 105   fprintf (stderr, ", %s", (vtable && vtable->name) ? vtable->name : "(null)");
 106   return 0;
 107 }
 108 
 109 void
 110 lt_dlloader_dump (void)
 111 {
 112   fprintf (stderr, "loaders: ");
 113   if (!loaders)
 114     {
 115       fprintf (stderr, "(empty)");
 116     }
 117   else
 118     {
 119       const lt_dlvtable *head = (const lt_dlvtable *) loaders->userdata;
 120       fprintf (stderr, "%s", (head && head->name) ? head->name : "(null)");
 121       if (slist_tail (loaders))
 122         slist_foreach (slist_tail (loaders), loader_dump_callback, NULL);
 123     }
 124   fprintf (stderr, "\n");
 125 }
 126 #endif
 127 
 128 /* An iterator for the global loader list: if LOADER is NULL, then
 129    return the first element, otherwise the following element.  */
 130 lt_dlloader
 131 lt_dlloader_next (lt_dlloader loader)
 132 {
 133   SList *item = (SList *) loader;
 134   return (lt_dlloader) (item ? item->next : loaders);
 135 }
 136 
 137 
 138 /* Non-destructive unboxing of a loader.  */
 139 const lt_dlvtable *
 140 lt_dlloader_get (lt_dlloader loader)
 141 {
 142   return (const lt_dlvtable *) (loader ? ((SList *) loader)->userdata : NULL);
 143 }
 144 
 145 
 146 /* Return the contents of the first item in the global loader list
 147    with a matching NAME after removing it from that list.  If there
 148    was no match, return NULL; if there is an error, return NULL and
 149    set an error for lt_dlerror; do not set an error if only resident
 150    modules need this loader; in either case, the loader list is not
 151    changed if NULL is returned.  */
 152 lt_dlvtable *
 153 lt_dlloader_remove (const char *name)
 154 {
 155   const lt_dlvtable *   vtable  = lt_dlloader_find (name);
 156   static const char     id_string[] = "lt_dlloader_remove";
 157   lt_dlinterface_id     iface;
 158   lt_dlhandle           handle = 0;
 159   int                   in_use = 0;
 160   int                   in_use_by_resident = 0;
 161 
 162   if (!vtable)
 163     {
 164       LT__SETERROR (INVALID_LOADER);
 165       return 0;
 166     }
 167 
 168   /* Fail if there are any open modules which use this loader.  */
 169   iface = lt_dlinterface_register (id_string, NULL);
 170   while ((handle = lt_dlhandle_iterate (iface, handle)))
 171     {
 172       lt_dlhandle cur = handle;
 173       if (cur->vtable == vtable)
 174         {
 175           in_use = 1;
 176           if (lt_dlisresident (handle))
 177             in_use_by_resident = 1;
 178         }
 179     }
 180   lt_dlinterface_free (iface);
 181   if (in_use)
 182     {
 183       if (!in_use_by_resident)
 184         LT__SETERROR (REMOVE_LOADER);
 185       return 0;
 186     }
 187 
 188   /* Call the loader finalisation function.  */
 189   if (vtable && vtable->dlloader_exit)
 190     {
 191       if ((*vtable->dlloader_exit) (vtable->dlloader_data) != 0)
 192         {
 193           /* If there is an exit function, and it returns non-zero
 194              then it must set an error, and we will not remove it
 195              from the list.  */
 196           return 0;
 197         }
 198     }
 199 
 200   /* If we got this far, remove the loader from our global list.  */
 201   return (lt_dlvtable *)
 202       slist_unbox ((SList *) slist_remove (&loaders, loader_callback, (void *) name));
 203 }
 204 
 205 
 206 const lt_dlvtable *
 207 lt_dlloader_find (const char *name)
 208 {
 209   return lt_dlloader_get (slist_find (loaders, loader_callback, (void *) name));
 210 }

/* */