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 extern int _dl_starting_up_internal attribute_hidden;
  30
  31
  32 static void
  33 call_init (struct link_map *l, int argc, char **argv, char **env)
  34 {
  35   if (l->l_init_called)
  36     /* This object is all done.  */
  37     return;
  38
  39   /* Avoid handling this constructor again in case we have a circular
  40      dependency.  */
  41   l->l_init_called = 1;
  42
  43   /* Check for object which constructors we do not run here.  */
  44   if (__builtin_expect (l->l_name[0], 'a') == '\0'
  45       && l->l_type == lt_executable)
  46     return;
  47
  48   /* Are there any constructors?  */
  49   if (l->l_info[DT_INIT] == NULL
  50       && __builtin_expect (l->l_info[DT_INIT_ARRAY] == NULL, 1))
  51     return;
  52
  53   /* Print a debug message if wanted.  */
  54   if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
  55     INTUSE(_dl_debug_printf) ("\ncalling init: %s\n\n",
  56                               l->l_name[0] ? l->l_name : rtld_progname);
  57
  58   /* Now run the local constructors.  There are two forms of them:
  59      - the one named by DT_INIT
  60      - the others in the DT_INIT_ARRAY.
  61   */
  62   if (l->l_info[DT_INIT] != NULL)
  63     {
  64       init_t init = (init_t) DL_DT_INIT_ADDRESS
  65         (l, l->l_addr + l->l_info[DT_INIT]->d_un.d_ptr);
  66
  67       /* Call the function.  */
  68       init (argc, argv, env);
  69     }
  70
  71   /* Next see whether there is an array with initialization functions.  */
  72   ElfW(Dyn) *init_array = l->l_info[DT_INIT_ARRAY];
  73   if (init_array != NULL)
  74     {
  75       unsigned int j;
  76       unsigned int jm;
  77       ElfW(Addr) *addrs;
  78
  79       jm = l->l_info[DT_INIT_ARRAYSZ]->d_un.d_val / sizeof (ElfW(Addr));
  80
  81       addrs = (ElfW(Addr) *) (init_array->d_un.d_ptr + l->l_addr);
  82       for (j = 0; j < jm; ++j)
  83         ((init_t) addrs[j]) (argc, argv, env);
  84     }
  85 }
  86
  87
  88 void
  89 internal_function
  90 _dl_init (struct link_map *main_map, int argc, char **argv, char **env)
  91 {
  92   ElfW(Dyn) *preinit_array = main_map->l_info[DT_PREINIT_ARRAY];
  93   ElfW(Dyn) *preinit_array_size = main_map->l_info[DT_PREINIT_ARRAYSZ];
  94   struct r_debug *r;
  95   unsigned int i;
  96
  97   if (__builtin_expect (GL(dl_initfirst) != NULL, 0))
  98     {
  99       call_init (GL(dl_initfirst), argc, argv, env);
 100       GL(dl_initfirst) = NULL;
 101     }
 102
 103   /* Don't do anything if there is no preinit array.  */
 104   if (__builtin_expect (preinit_array != NULL, 0)
 105       && preinit_array_size != NULL
 106       && (i = preinit_array_size->d_un.d_val / sizeof (ElfW(Addr))) > 0)
 107     {
 108       ElfW(Addr) *addrs;
 109       unsigned int cnt;
 110
 111       if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
 112         INTUSE(_dl_debug_printf) ("\ncalling preinit: %s\n\n",
 113                                   main_map->l_name[0]
 114                                   ? main_map->l_name : rtld_progname);
 115
 116       addrs = (ElfW(Addr) *) (preinit_array->d_un.d_ptr + main_map->l_addr);
 117       for (cnt = 0; cnt < i; ++cnt)
 118         ((init_t) addrs[cnt]) (argc, argv, env);
 119     }
 120
 121   /* Notify the debugger we have added some objects.  We need to call
 122      _dl_debug_initialize in a static program in case dynamic linking has
 123      not been used before.  */
 124   r = _dl_debug_initialize (0);
 125   r->r_state = RT_ADD;
 126   INTUSE(_dl_debug_state) ();
 127
 128   /* Stupid users forced the ELF specification to be changed.  It now
 129      says that the dynamic loader is responsible for determining the
 130      order in which the constructors have to run.  The constructors
 131      for all dependencies of an object must run before the constructor
 132      for the object itself.  Circular dependencies are left unspecified.
 133
 134      This is highly questionable since it puts the burden on the dynamic
 135      loader which has to find the dependencies at runtime instead of
 136      letting the user do it right.  Stupidity rules!  */
 137
 138   i = main_map->l_searchlist.r_nlist;
 139   while (i-- > 0)
 140     call_init (main_map->l_initfini[i], argc, argv, env);
 141
 142   /* Notify the debugger all new objects are now ready to go.  */
 143   r->r_state = RT_CONSISTENT;
 144   INTUSE(_dl_debug_state) ();
 145
 146   /* Finished starting up.  */
 147   INTUSE(_dl_starting_up) = 0;
 148 }
 149 INTDEF (_dl_init)