elf/dl-init.c

   1 /* Return the next shared object initializer function not yet run.
   2    Copyright (C) 1995, 1996, 1998-2001, 2002 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 Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <stddef.h>
  21 #include <ldsodefs.h>
  22
  23
  24 /* Type of the initializer.  */
  25 typedef void (*init_t) (int, char **, char **);
  26
  27 /* Flag, nonzero during startup phase.  */
  28 extern int _dl_starting_up;
  29
  30
  31 static void
  32 call_init (struct link_map *l, int argc, char **argv, char **env)
  33 {
  34   if (l->l_init_called)
  35     /* This object is all done.  */
  36     return;
  37
  38   /* Avoid handling this constructor again in case we have a circular
  39      dependency.  */
  40   l->l_init_called = 1;
  41
  42   /* Check for object which constructors we do not run here.  */
  43   if (__builtin_expect (l->l_name[0], 'a') == '\0'
  44       && l->l_type == lt_executable)
  45     return;
  46
  47   /* Are there any constructors?  */
  48   if (l->l_info[DT_INIT] == NULL
  49       && __builtin_expect (l->l_info[DT_INIT_ARRAY] == NULL, 1))
  50     return;
  51
  52   /* Print a debug message if wanted.  */
  53   if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
  54     INTUSE(_dl_debug_printf) ("\ncalling init: %s\n\n",
  55                               l->l_name[0] ? l->l_name : _dl_argv[0]);
  56
  57   /* Now run the local constructors.  There are two forms of them:
  58      - the one named by DT_INIT
  59      - the others in the DT_INIT_ARRAY.
  60   */
  61   if (l->l_info[DT_INIT] != NULL)
  62     {
  63       init_t init = (init_t) DL_DT_INIT_ADDRESS
  64         (l, l->l_addr + l->l_info[DT_INIT]->d_un.d_ptr);
  65
  66       /* Call the function.  */
  67       init (argc, argv, env);
  68     }
  69
  70   /* Next see whether there is an array with initialization functions.  */
  71   if (l->l_info[DT_INIT_ARRAY] != NULL)
  72     {
  73       unsigned int j;
  74       unsigned int jm;
  75       ElfW(Addr) *addrs;
  76
  77       jm = l->l_info[DT_INIT_ARRAYSZ]->d_un.d_val / sizeof (ElfW(Addr));
  78
  79       addrs = (ElfW(Addr) *) (l->l_info[DT_INIT_ARRAY]->d_un.d_ptr
  80                               + l->l_addr);
  81       for (j = 0; j < jm; ++j)
  82         ((init_t) addrs[j]) (argc, argv, env);
  83     }
  84 }
  85
  86
  87 void
  88 internal_function
  89 _dl_init (struct link_map *main_map, int argc, char **argv, char **env)
  90 {
  91   ElfW(Dyn) *preinit_array = main_map->l_info[DT_PREINIT_ARRAY];
  92   struct r_debug *r;
  93   unsigned int i;
  94
  95   if (__builtin_expect (GL(dl_initfirst) != NULL, 0))
  96     {
  97       call_init (GL(dl_initfirst), argc, argv, env);
  98       GL(dl_initfirst) = NULL;
  99     }
 100
 101   /* Don't do anything if there is no preinit array.  */
 102   if (__builtin_expect (preinit_array != NULL, 0)
 103       && (i = preinit_array->d_un.d_val / sizeof (ElfW(Addr))) > 0)
 104     {
 105       ElfW(Addr) *addrs;
 106       unsigned int cnt;
 107
 108       if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
 109         INTUSE(_dl_debug_printf) ("\ncalling preinit: %s\n\n",
 110                                   main_map->l_name[0]
 111                                   ? main_map->l_name : _dl_argv[0]);
 112
 113       addrs = (ElfW(Addr) *) (main_map->l_info[DT_PREINIT_ARRAY]->d_un.d_ptr
 114                               + main_map->l_addr);
 115       for (cnt = 0; cnt < i; ++cnt)
 116         ((init_t) addrs[cnt]) (argc, argv, env);
 117     }
 118
 119   /* Notify the debugger we have added some objects.  We need to call
 120      _dl_debug_initialize in a static program in case dynamic linking has
 121      not been used before.  */
 122   r = _dl_debug_initialize (0);
 123   r->r_state = RT_ADD;
 124   INTUSE(_dl_debug_state) ();
 125
 126   /* Stupid users forced the ELF specification to be changed.  It now
 127      says that the dynamic loader is responsible for determining the
 128      order in which the constructors have to run.  The constructors
 129      for all dependencies of an object must run before the constructor
 130      for the object itself.  Circular dependencies are left unspecified.
 131
 132      This is highly questionable since it puts the burden on the dynamic
 133      loader which has to find the dependencies at runtime instead of
 134      letting the user do it right.  Stupidity rules!  */
 135
 136   i = main_map->l_searchlist.r_nlist;
 137   while (i-- > 0)
 138     call_init (main_map->l_initfini[i], argc, argv, env);
 139
 140   /* Notify the debugger all new objects are now ready to go.  */
 141   r->r_state = RT_CONSISTENT;
 142   INTUSE(_dl_debug_state) ();
 143
 144   /* Finished starting up.  */
 145   _dl_starting_up = 0;
 146 }
 147 INTDEF (_dl_init)