elf/dl-close.c

   1 /* Close a shared object opened by `_dl_open'.
   2    Copyright (C) 1996,1997,1998,1999,2000,2001 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <assert.h>
  21 #include <dlfcn.h>
  22 #include <libintl.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <bits/libc-lock.h>
  26 #include <ldsodefs.h>
  27 #include <sys/types.h>
  28 #include <sys/mman.h>
  29
  30
  31 /* Type of the constructor functions.  */
  32 typedef void (*fini_t) (void);
  33
  34
  35 /* During the program run we must not modify the global data of
  36    loaded shared object simultanously in two threads.  Therefore we
  37    protect `dlopen' and `dlclose' in dlclose.c.  */
  38 __libc_lock_define (extern, _dl_load_lock)
  39
  40 void
  41 internal_function
  42 _dl_close (void *_map)
  43 {
  44   struct reldep_list
  45   {
  46     struct link_map **rellist;
  47     unsigned int nrellist;
  48     struct reldep_list *next;
  49   } *reldeps = NULL;
  50   struct link_map **list;
  51   struct link_map *map = _map;
  52   unsigned int i;
  53   unsigned int *new_opencount;
  54
  55   /* First see whether we can remove the object at all.  */
  56   if ((map->l_flags_1 & DF_1_NODELETE) && map->l_init_called)
  57     /* Nope.  Do nothing.  */
  58     return;
  59
  60   if (__builtin_expect (map->l_opencount, 1) == 0)
  61     _dl_signal_error (0, map->l_name, N_("shared object not open"));
  62
  63   /* Acquire the lock.  */
  64   __libc_lock_lock (_dl_load_lock);
  65
  66   /* Decrement the reference count.  */
  67   if (map->l_opencount > 1 || map->l_type != lt_loaded)
  68     {
  69       /* There are still references to this object.  Do nothing more.  */
  70       if (//__builtin_expect (_dl_debug_files, 0))
  71           __builtin_expect (_dl_debug_mask & DL_DEBUG_FILES, 0))
  72         {
  73           char buf[20];
  74
  75           buf[sizeof buf - 1] = '\0';
  76
  77           _dl_debug_printf ("\nclosing file=%s; opencount == %u\n",
  78                             map->l_name, map->l_opencount);
  79         }
  80
  81       /* One decrement the object itself, not the dependencies.  */
  82       --map->l_opencount;
  83
  84       __libc_lock_unlock (_dl_load_lock);
  85       return;
  86     }
  87
  88   list = map->l_initfini;
  89
  90   /* Compute the new l_opencount values.  */
  91   new_opencount = (unsigned int *) alloca (map->l_searchlist.r_nlist
  92                                            * sizeof (unsigned int));
  93   for (i = 0; list[i] != NULL; ++i)
  94     {
  95       list[i]->l_idx = i;
  96       new_opencount[i] = list[i]->l_opencount;
  97     }
  98   --new_opencount[0];
  99   for (i = 1; list[i] != NULL; ++i)
 100     if ((! (list[i]->l_flags_1 & DF_1_NODELETE) || ! list[i]->l_init_called)
 101         /* Decrement counter.  */
 102         && --new_opencount[i] == 0
 103         /* Test whether this object was also loaded directly.  */
 104         && list[i]->l_searchlist.r_list != NULL)
 105       {
 106         /* In this case we have the decrement all the dependencies of
 107            this object.  They are all in MAP's dependency list.  */
 108         unsigned int j;
 109         struct link_map **dep_list = list[i]->l_searchlist.r_list;
 110
 111         for (j = 1; j < list[i]->l_searchlist.r_nlist; ++j)
 112           if (! (dep_list[j]->l_flags_1 & DF_1_NODELETE)
 113               || ! dep_list[j]->l_init_called)
 114             {
 115               assert (dep_list[j]->l_idx < map->l_searchlist.r_nlist);
 116               --new_opencount[dep_list[j]->l_idx];
 117             }
 118       }
 119   assert (new_opencount[0] == 0);
 120
 121   /* Call all termination functions at once.  */
 122   for (i = 0; list[i] != NULL; ++i)
 123     {
 124       struct link_map *imap = list[i];
 125       if (new_opencount[i] == 0 && imap->l_type == lt_loaded
 126           && (imap->l_info[DT_FINI] || imap->l_info[DT_FINI_ARRAY])
 127           && (! (imap->l_flags_1 & DF_1_NODELETE) || ! imap->l_init_called)
 128           /* Skip any half-cooked objects that were never initialized.  */
 129           && imap->l_init_called)
 130         {
 131           /* When debugging print a message first.  */
 132           if (__builtin_expect (_dl_debug_mask & DL_DEBUG_IMPCALLS, 0))
 133             _dl_debug_printf ("\ncalling fini: %s\n\n", imap->l_name);
 134
 135           /* Call its termination function.  */
 136           if (imap->l_info[DT_FINI_ARRAY] != NULL)
 137             {
 138               ElfW(Addr) *array =
 139                 (ElfW(Addr) *) (imap->l_addr
 140                                 + imap->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
 141               unsigned int sz = (imap->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
 142                                  / sizeof (ElfW(Addr)));
 143               unsigned int cnt;
 144
 145               for (cnt = 0; cnt < sz; ++cnt)
 146                 ((fini_t) (imap->l_addr + array[cnt])) ();
 147             }
 148
 149           /* Next try the old-style destructor.  */
 150           if (imap->l_info[DT_FINI] != NULL)
 151             (*(void (*) (void)) DL_DT_FINI_ADDRESS
 152               (imap, (void *) imap->l_addr
 153                      + imap->l_info[DT_FINI]->d_un.d_ptr)) ();
 154         }
 155
 156       /* Store the new l_opencount value.  */
 157       imap->l_opencount = new_opencount[i];
 158       /* Just a sanity check.  */
 159       assert (imap->l_type == lt_loaded || imap->l_opencount > 0);
 160     }
 161
 162   /* Notify the debugger we are about to remove some loaded objects.  */
 163   _r_debug.r_state = RT_DELETE;
 164   _dl_debug_state ();
 165
 166   /* Check each element of the search list to see if all references to
 167      it are gone.  */
 168   for (i = 0; list[i] != NULL; ++i)
 169     {
 170       struct link_map *imap = list[i];
 171       if (imap->l_opencount == 0 && imap->l_type == lt_loaded)
 172         {
 173           struct libname_list *lnp;
 174
 175           /* That was the last reference, and this was a dlopen-loaded
 176              object.  We can unmap it.  */
 177           if (__builtin_expect (imap->l_global, 0))
 178             {
 179               /* This object is in the global scope list.  Remove it.  */
 180               unsigned int cnt = _dl_main_searchlist->r_nlist;
 181
 182               do
 183                 --cnt;
 184               while (_dl_main_searchlist->r_list[cnt] != imap);
 185
 186               /* The object was already correctly registered.  */
 187               while (++cnt < _dl_main_searchlist->r_nlist)
 188                 _dl_main_searchlist->r_list[cnt - 1]
 189                   = _dl_main_searchlist->r_list[cnt];
 190
 191               --_dl_main_searchlist->r_nlist;
 192             }
 193
 194           /* We can unmap all the maps at once.  We determined the
 195              start address and length when we loaded the object and
 196              the `munmap' call does the rest.  */
 197           DL_UNMAP (imap);
 198
 199           /* Finally, unlink the data structure and free it.  */
 200 #ifdef SHARED
 201           /* We will unlink the first object only if this is a statically
 202              linked program.  */
 203           assert (imap->l_prev != NULL);
 204           imap->l_prev->l_next = imap->l_next;
 205 #else
 206           if (imap->l_prev != NULL)
 207             imap->l_prev->l_next = imap->l_next;
 208           else
 209             _dl_loaded = imap->l_next;
 210 #endif
 211           --_dl_nloaded;
 212           if (imap->l_next)
 213             imap->l_next->l_prev = imap->l_prev;
 214
 215           if (imap->l_versions != NULL)
 216             free (imap->l_versions);
 217           if (imap->l_origin != NULL && imap->l_origin != (char *) -1)
 218             free ((char *) imap->l_origin);
 219
 220           /* If the object has relocation dependencies save this
 221              information for latter.  */
 222           if (__builtin_expect (imap->l_reldeps != NULL, 0))
 223             {
 224               struct reldep_list *newrel;
 225
 226               newrel = (struct reldep_list *) alloca (sizeof (*reldeps));
 227               newrel->rellist = imap->l_reldeps;
 228               newrel->nrellist = imap->l_reldepsact;
 229               newrel->next = reldeps;
 230
 231               reldeps = newrel;
 232             }
 233
 234           /* This name always is allocated.  */
 235           free (imap->l_name);
 236           /* Remove the list with all the names of the shared object.  */
 237           lnp = imap->l_libname;
 238           do
 239             {
 240               struct libname_list *this = lnp;
 241               lnp = lnp->next;
 242               free (this);
 243             }
 244           while (lnp != NULL);
 245
 246           /* Remove the searchlists.  */
 247           if (imap != map)
 248               free (imap->l_initfini);
 249
 250           if (imap->l_phdr_allocated)
 251             free ((void *) imap->l_phdr);
 252
 253           if (imap->l_rpath_dirs.dirs != (void *) -1)
 254             free (imap->l_rpath_dirs.dirs);
 255           if (imap->l_runpath_dirs.dirs != (void *) -1)
 256             free (imap->l_runpath_dirs.dirs);
 257
 258           free (imap);
 259         }
 260     }
 261
 262   /* Notify the debugger those objects are finalized and gone.  */
 263   _r_debug.r_state = RT_CONSISTENT;
 264   _dl_debug_state ();
 265
 266   /* Now we can perhaps also remove the modules for which we had
 267      dependencies because of symbol lookup.  */
 268   while (__builtin_expect (reldeps != NULL, 0))
 269     {
 270       while (reldeps->nrellist-- > 0)
 271         _dl_close (reldeps->rellist[reldeps->nrellist]);
 272
 273       free (reldeps->rellist);
 274
 275       reldeps = reldeps->next;
 276     }
 277
 278   free (list);
 279
 280   /* Release the lock.  */
 281   __libc_lock_unlock (_dl_load_lock);
 282 }
 283
 284
 285 static void
 286 free_mem (void)
 287 {
 288   if (__builtin_expect (_dl_global_scope_alloc, 0) != 0
 289       && _dl_main_searchlist->r_nlist == _dl_initial_searchlist.r_nlist)
 290     {
 291       /* All object dynamically loaded by the program are unloaded.  Free
 292          the memory allocated for the global scope variable.  */
 293       struct link_map **old = _dl_main_searchlist->r_list;
 294
 295       /* Put the old map in.  */
 296       _dl_main_searchlist->r_list = _dl_initial_searchlist.r_list;
 297       /* Signal that the original map is used.  */
 298       _dl_global_scope_alloc = 0;
 299
 300       /* Now free the old map.  */
 301       free (old);
 302     }
 303 }
 304 text_set_element (__libc_subfreeres, free_mem);