elf/dl-init.c

   1 /* Return the next shared object initializer function not yet run.
   2    Copyright (C) 1995, 1996, 1998-2002, 2004 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 #ifndef HAVE_INLINED_SYSCALLS
  28 /* Flag, nonzero during startup phase.  */
  29 extern int _dl_starting_up;
  30 extern int _dl_starting_up_internal attribute_hidden;
  31 #endif
  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 (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
  57     _dl_debug_printf ("\ncalling init: %s\n\n",
  58                       l->l_name[0] ? l->l_name : rtld_progname);
  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   ElfW(Dyn) *init_array = l->l_info[DT_INIT_ARRAY];
  75   if (init_array != NULL)
  76     {
  77       unsigned int j;
  78       unsigned int jm;
  79       ElfW(Addr) *addrs;
  80
  81       jm = l->l_info[DT_INIT_ARRAYSZ]->d_un.d_val / sizeof (ElfW(Addr));
  82
  83       addrs = (ElfW(Addr) *) (init_array->d_un.d_ptr + 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   ElfW(Dyn) *preinit_array_size = main_map->l_info[DT_PREINIT_ARRAYSZ];
  96   struct r_debug *r;
  97   unsigned int i;
  98
  99   if (__builtin_expect (GL(dl_initfirst) != NULL, 0))
 100     {
 101       call_init (GL(dl_initfirst), argc, argv, env);
 102       GL(dl_initfirst) = NULL;
 103     }
 104
 105   /* Don't do anything if there is no preinit array.  */
 106   if (__builtin_expect (preinit_array != NULL, 0)
 107       && preinit_array_size != NULL
 108       && (i = preinit_array_size->d_un.d_val / sizeof (ElfW(Addr))) > 0)
 109     {
 110       ElfW(Addr) *addrs;
 111       unsigned int cnt;
 112
 113       if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
 114         _dl_debug_printf ("\ncalling preinit: %s\n\n",
 115                           main_map->l_name[0]
 116                           ? main_map->l_name : rtld_progname);
 117
 118       addrs = (ElfW(Addr) *) (preinit_array->d_un.d_ptr + main_map->l_addr);
 119       for (cnt = 0; cnt < i; ++cnt)
 120         ((init_t) addrs[cnt]) (argc, argv, env);
 121     }
 122
 123   /* Notify the debugger we have added some objects.  We need to call
 124      _dl_debug_initialize in a static program in case dynamic linking has
 125      not been used before.  */
 126   r = _dl_debug_initialize (0);
 127   r->r_state = RT_ADD;
 128   _dl_debug_state ();
 129
 130   /* Stupid users forced the ELF specification to be changed.  It now
 131      says that the dynamic loader is responsible for determining the
 132      order in which the constructors have to run.  The constructors
 133      for all dependencies of an object must run before the constructor
 134      for the object itself.  Circular dependencies are left unspecified.
 135
 136      This is highly questionable since it puts the burden on the dynamic
 137      loader which has to find the dependencies at runtime instead of
 138      letting the user do it right.  Stupidity rules!  */
 139
 140   i = main_map->l_searchlist.r_nlist;
 141   while (i-- > 0)
 142     call_init (main_map->l_initfini[i], argc, argv, env);
 143
 144   /* Notify the debugger all new objects are now ready to go.  */
 145   r->r_state = RT_CONSISTENT;
 146   _dl_debug_state ();
 147
 148 #ifndef HAVE_INLINED_SYSCALLS
 149   /* Finished starting up.  */
 150   INTUSE(_dl_starting_up) = 0;
 151 #endif
 152 }
 153 INTDEF (_dl_init)