about summary refs log tree commit diff
path: root/elf/dl-sym.c
blob: e3447d947056c063372e38701ac98f8c784d06ed (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
/* Look up a symbol in a shared object loaded by `dlopen'.
   Copyright (C) 1999, 2000, 2001, 2002, 2004 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <stddef.h>
#include <setjmp.h>
#include <libintl.h>

#include <dlfcn.h>
#include <ldsodefs.h>
#include <dl-hash.h>
#ifdef USE_TLS
# include <dl-tls.h>
#endif


#if defined USE_TLS && defined SHARED
/* Systems which do not have tls_index also probably have to define
   DONT_USE_TLS_INDEX.  */

# ifndef __TLS_GET_ADDR
#  define __TLS_GET_ADDR __tls_get_addr
# endif

/* Return the symbol address given the map of the module it is in and
   the symbol record.  This is used in dl-sym.c.  */
static void *
internal_function
_dl_tls_symaddr (struct link_map *map, const ElfW(Sym) *ref)
{
# ifndef DONT_USE_TLS_INDEX
  tls_index tmp =
    {
      .ti_module = map->l_tls_modid,
      .ti_offset = ref->st_value
    };

  return __TLS_GET_ADDR (&tmp);
# else
  return __TLS_GET_ADDR (map->l_tls_modid, ref->st_value);
# endif
}
#endif


static void *
internal_function
do_sym (void *handle, const char *name, struct r_found_version *vers,
	int flags, void *who)
{
  const ElfW(Sym) *ref = NULL;
  lookup_t result;
  ElfW(Addr) caller = (ElfW(Addr)) who;

  /* If the address is not recognized the call comes from the main
     program (we hope).  */
  struct link_map *match = GL(dl_loaded);

  /* Find the highest-addressed object that CALLER is not below.  */
  for (struct link_map *l = GL(dl_loaded); l != NULL; l = l->l_next)
    if (caller >= l->l_map_start && caller < l->l_map_end)
      {
	/* There must be exactly one DSO for the range of the virtual
	   memory.  Otherwise something is really broken.  */
	match = l;
	break;
      }

  if (handle == RTLD_DEFAULT)
    /* Search the global scope.  */
    result = GLRO(dl_lookup_symbol_x) (name, match, &ref, match->l_scope,
				       vers, 0, flags|DL_LOOKUP_ADD_DEPENDENCY,
				       NULL);
  else if (handle == RTLD_NEXT)
    {
      if (__builtin_expect (match == GL(dl_loaded), 0))
	{
	  if (! GL(dl_loaded)
	      || caller < GL(dl_loaded)->l_map_start
	      || caller >= GL(dl_loaded)->l_map_end)
	    GLRO(dl_signal_error) (0, NULL, NULL, N_("\
RTLD_NEXT used in code not dynamically loaded"));
	}

      struct link_map *l = match;
      while (l->l_loader != NULL)
	l = l->l_loader;

      result = GLRO(dl_lookup_symbol_x) (name, l, &ref, l->l_local_scope,
					 vers, 0, 0, match);
    }
  else
    {
      /* Search the scope of the given object.  */
      struct link_map *map = handle;
      result = GLRO(dl_lookup_symbol_x) (name, map, &ref, map->l_local_scope,
					 vers, 0, flags, NULL);
    }

  if (ref != NULL)
    {
#if defined USE_TLS && defined SHARED
      if (ELFW(ST_TYPE) (ref->st_info) == STT_TLS)
	/* The found symbol is a thread-local storage variable.
	   Return the address for to the current thread.  */
	return _dl_tls_symaddr (result, ref);
#endif

      return DL_SYMBOL_ADDRESS (result, ref);
    }

  return NULL;
}



void *
internal_function
_dl_vsym (void *handle, const char *name, const char *version, void *who)
{
  struct r_found_version vers;

  /* Compute hash value to the version string.  */
  vers.name = version;
  vers.hidden = 1;
  vers.hash = _dl_elf_hash (version);
  /* We don't have a specific file where the symbol can be found.  */
  vers.filename = NULL;

  return do_sym (handle, name, &vers, 0, who);
}


void *
internal_function
_dl_sym (void *handle, const char *name, void *who)
{
  return do_sym (handle, name, NULL, DL_LOOKUP_RETURN_NEWEST, who);
}