elf/dl-init.c

   1 /* Run initializers for newly loaded objects.
   2    Copyright (C) 1995,1996,1998-2002, 2004,2012 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   unsigned int i;
  97
  98   if (__builtin_expect (GL(dl_initfirst) != NULL, 0))
  99     {
 100       call_init (GL(dl_initfirst), argc, argv, env);
 101       GL(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       && preinit_array_size != NULL
 107       && (i = preinit_array_size->d_un.d_val / sizeof (ElfW(Addr))) > 0)
 108     {
 109       ElfW(Addr) *addrs;
 110       unsigned int cnt;
 111
 112       if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
 113         _dl_debug_printf ("\ncalling preinit: %s\n\n",
 114                           main_map->l_name[0]
 115                           ? main_map->l_name : rtld_progname);
 116
 117       addrs = (ElfW(Addr) *) (preinit_array->d_un.d_ptr + main_map->l_addr);
 118       for (cnt = 0; cnt < i; ++cnt)
 119         ((init_t) addrs[cnt]) (argc, argv, env);
 120     }
 121
 122   /* Stupid users forced the ELF specification to be changed.  It now
 123      says that the dynamic loader is responsible for determining the
 124      order in which the constructors have to run.  The constructors
 125      for all dependencies of an object must run before the constructor
 126      for the object itself.  Circular dependencies are left unspecified.
 127
 128      This is highly questionable since it puts the burden on the dynamic
 129      loader which has to find the dependencies at runtime instead of
 130      letting the user do it right.  Stupidity rules!  */
 131
 132   i = main_map->l_searchlist.r_nlist;
 133   while (i-- > 0)
 134     call_init (main_map->l_initfini[i], argc, argv, env);
 135
 136 #ifndef HAVE_INLINED_SYSCALLS
 137   /* Finished starting up.  */
 138   INTUSE(_dl_starting_up) = 0;
 139 #endif
 140 }
 141 INTDEF (_dl_init)