elf/dl-init.c

   1 /* Return the next shared object initializer function not yet run.
   2    Copyright (C) 1995,1996,1998,1999,2000,2001 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 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 /* The object to be initialized first.  */
  31 extern struct link_map *_dl_initfirst;
  32
  33
  34 static void
  35 call_init (struct link_map *l, int argc, char **argv, char **env)
  36 {
  37   if (l->l_init_called)
  38     /* This object is all done.  */
  39     return;
  40
  41   /* Avoid handling this constructor again in case we have a circular
  42      dependency.  */
  43   l->l_init_called = 1;
  44
  45   /* Check for object which constructors we do not run here.  */
  46   if (__builtin_expect (l->l_name[0], 'a') == '\0'
  47       && l->l_type == lt_executable)
  48     return;
  49
  50   /* Are there any constructors?  */
  51   if (l->l_info[DT_INIT] == NULL
  52       && __builtin_expect (l->l_info[DT_INIT_ARRAY] == NULL, 1))
  53     return;
  54
  55   /* Print a debug message if wanted.  */
  56   if (__builtin_expect (_dl_debug_mask & DL_DEBUG_IMPCALLS, 0))
  57     _dl_debug_printf ("\ncalling init: %s\n\n",
  58                       l->l_name[0] ? l->l_name : _dl_argv[0]);
  59
  60   /* Now run the local constructors.  There are two forms of them:
  61      - the one named by DT_INIT
  62      - the others in the DT_INIT_ARRAY.
  63   */
  64   if (l->l_info[DT_INIT] != NULL)
  65     {
  66       init_t init = (init_t) DL_DT_INIT_ADDRESS
  67         (l, l->l_addr + l->l_info[DT_INIT]->d_un.d_ptr);
  68
  69       /* Call the function.  */
  70       init (argc, argv, env);
  71     }
  72
  73   /* Next see whether there is an array with initialization functions.  */
  74   if (l->l_info[DT_INIT_ARRAY] != NULL)
  75     {
  76       unsigned int j;
  77       unsigned int jm;
  78       ElfW(Addr) *addrs;
  79
  80       jm = l->l_info[DT_INIT_ARRAYSZ]->d_un.d_val / sizeof (ElfW(Addr));
  81
  82       addrs = (ElfW(Addr) *) (l->l_info[DT_INIT_ARRAY]->d_un.d_ptr
  83                               + l->l_addr);
  84       for (j = 0; j < jm; ++j)
  85         ((init_t) addrs[j]) (argc, argv, env);
  86     }
  87 }
  88
  89
  90 void
  91 internal_function
  92 _dl_init (struct link_map *main_map, int argc, char **argv, char **env)
  93 {
  94   ElfW(Dyn) *preinit_array = main_map->l_info[DT_PREINIT_ARRAY];
  95   struct r_debug *r;
  96   unsigned int i;
  97
  98   if (__builtin_expect (_dl_initfirst != NULL, 0))
  99     {
 100       call_init (_dl_initfirst, argc, argv, env);
 101       _dl_initfirst = NULL;
 102     }
 103
 104   /* Don't do anything if there is no preinit array.  */
 105   if (__builtin_expect (preinit_array != NULL, 0)
 106       && (i = preinit_array->d_un.d_val / sizeof (ElfW(Addr))) > 0)
 107     {
 108       ElfW(Addr) *addrs;
 109       unsigned int cnt;
 110
 111       if (__builtin_expect (_dl_debug_mask & DL_DEBUG_IMPCALLS, 0))
 112         _dl_debug_printf ("\ncalling preinit: %s\n\n",
 113                           main_map->l_name[0]
 114                           ? main_map->l_name : _dl_argv[0]);
 115
 116       addrs = (ElfW(Addr) *) (main_map->l_info[DT_PREINIT_ARRAY]->d_un.d_ptr
 117                               + main_map->l_addr);
 118       for (cnt = 0; cnt < i; ++cnt)
 119         ((init_t) addrs[cnt]) (argc, argv, env);
 120     }
 121
 122   /* Notify the debugger we have added some objects.  We need to call
 123      _dl_debug_initialize in a static program in case dynamic linking has
 124      not been used before.  */
 125   r = _dl_debug_initialize (0);
 126   r->r_state = RT_ADD;
 127   _dl_debug_state ();
 128
 129   /* Stupid users forced the ELF specification to be changed.  It now
 130      says that the dynamic loader is responsible for determining the
 131      order in which the constructors have to run.  The constructors
 132      for all dependencies of an object must run before the constructor
 133      for the object itself.  Circular dependencies are left unspecified.
 134
 135      This is highly questionable since it puts the burden on the dynamic
 136      loader which has to find the dependencies at runtime instead of
 137      letting the user do it right.  Stupidity rules!  */
 138
 139   i = main_map->l_searchlist.r_nlist;
 140   while (i-- > 0)
 141     call_init (main_map->l_initfini[i], argc, argv, env);
 142
 143   /* Notify the debugger all new objects are now ready to go.  */
 144   r->r_state = RT_CONSISTENT;
 145   _dl_debug_state ();
 146
 147   /* Finished starting up.  */
 148   _dl_starting_up = 0;
 149 }