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   if (l->l_info[DT_INIT_ARRAY] != NULL)
  73     {
  74       unsigned int j;
  75       unsigned int jm;
  76       ElfW(Addr) *addrs;
  77
  78       jm = l->l_info[DT_INIT_ARRAYSZ]->d_un.d_val / sizeof (ElfW(Addr));
  79
  80       addrs = (ElfW(Addr) *) (l->l_info[DT_INIT_ARRAY]->d_un.d_ptr
  81                               + 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   struct r_debug *r;
  94   unsigned int i;
  95
  96   if (__builtin_expect (GL(dl_initfirst) != NULL, 0))
  97     {
  98       call_init (GL(dl_initfirst), argc, argv, env);
  99       GL(dl_initfirst) = NULL;
 100     }
 101
 102   /* Don't do anything if there is no preinit array.  */
 103   if (__builtin_expect (preinit_array != NULL, 0)
 104       && (i = preinit_array->d_un.d_val / sizeof (ElfW(Addr))) > 0)
 105     {
 106       ElfW(Addr) *addrs;
 107       unsigned int cnt;
 108
 109       if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
 110         INTUSE(_dl_debug_printf) ("\ncalling preinit: %s\n\n",
 111                                   main_map->l_name[0]
 112                                   ? main_map->l_name : rtld_progname);
 113
 114       addrs = (ElfW(Addr) *) (main_map->l_info[DT_PREINIT_ARRAY]->d_un.d_ptr
 115                               + main_map->l_addr);
 116       for (cnt = 0; cnt < i; ++cnt)
 117         ((init_t) addrs[cnt]) (argc, argv, env);
 118     }
 119
 120   /* Notify the debugger we have added some objects.  We need to call
 121      _dl_debug_initialize in a static program in case dynamic linking has
 122      not been used before.  */
 123   r = _dl_debug_initialize (0);
 124   r->r_state = RT_ADD;
 125   INTUSE(_dl_debug_state) ();
 126
 127   /* Stupid users forced the ELF specification to be changed.  It now
 128      says that the dynamic loader is responsible for determining the
 129      order in which the constructors have to run.  The constructors
 130      for all dependencies of an object must run before the constructor
 131      for the object itself.  Circular dependencies are left unspecified.
 132
 133      This is highly questionable since it puts the burden on the dynamic
 134      loader which has to find the dependencies at runtime instead of
 135      letting the user do it right.  Stupidity rules!  */
 136
 137   i = main_map->l_searchlist.r_nlist;
 138   while (i-- > 0)
 139     call_init (main_map->l_initfini[i], argc, argv, env);
 140
 141   /* Notify the debugger all new objects are now ready to go.  */
 142   r->r_state = RT_CONSISTENT;
 143   INTUSE(_dl_debug_state) ();
 144
 145   /* Finished starting up.  */
 146   INTUSE(_dl_starting_up) = 0;
 147 }
 148 INTDEF (_dl_init)