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
|
/* Locate the shared object symbol nearest a given address.
Copyright (C) 1996-2018 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, see
<http://www.gnu.org/licenses/>. */
#include <dlfcn.h>
#include <stddef.h>
#include <ldsodefs.h>
static inline void
__attribute ((always_inline))
determine_info (const ElfW(Addr) addr, struct link_map *match, Dl_info *info,
struct link_map **mapp, const ElfW(Sym) **symbolp)
{
/* Now we know what object the address lies in. */
info->dli_fname = match->l_name;
info->dli_fbase = (void *) match->l_map_start;
/* If this is the main program the information is incomplete. */
if (__builtin_expect (match->l_name[0], 'a') == '\0'
&& match->l_type == lt_executable)
info->dli_fname = _dl_argv[0];
const ElfW(Sym) *symtab
= (const ElfW(Sym) *) D_PTR (match, l_info[DT_SYMTAB]);
const char *strtab = (const char *) D_PTR (match, l_info[DT_STRTAB]);
ElfW(Word) strtabsize = match->l_info[DT_STRSZ]->d_un.d_val;
const ElfW(Sym) *matchsym = NULL;
if (match->l_info[DT_ADDRTAGIDX (DT_GNU_HASH) + DT_NUM + DT_THISPROCNUM
+ DT_VERSIONTAGNUM + DT_EXTRANUM + DT_VALNUM] != NULL)
{
/* We look at all symbol table entries referenced by the hash
table. */
for (Elf_Symndx bucket = 0; bucket < match->l_nbuckets; ++bucket)
{
Elf32_Word symndx = match->l_gnu_buckets[bucket];
if (symndx != 0)
{
const Elf32_Word *hasharr = &match->l_gnu_chain_zero[symndx];
do
{
/* The hash table never references local symbols so
we can omit that test here. */
if ((symtab[symndx].st_shndx != SHN_UNDEF
|| symtab[symndx].st_value != 0)
&& ELFW(ST_TYPE) (symtab[symndx].st_info) != STT_TLS
&& DL_ADDR_SYM_MATCH (match, &symtab[symndx],
matchsym, addr)
&& symtab[symndx].st_name < strtabsize)
matchsym = (ElfW(Sym) *) &symtab[symndx];
++symndx;
}
while ((*hasharr++ & 1u) == 0);
}
}
}
else
{
const ElfW(Sym) *symtabend;
if (match->l_info[DT_HASH] != NULL)
symtabend = (symtab
+ ((Elf_Symndx *) D_PTR (match, l_info[DT_HASH]))[1]);
else
/* There is no direct way to determine the number of symbols in the
dynamic symbol table and no hash table is present. The ELF
binary is ill-formed but what shall we do? Use the beginning of
the string table which generally follows the symbol table. */
symtabend = (const ElfW(Sym) *) strtab;
for (; (void *) symtab < (void *) symtabend; ++symtab)
if ((ELFW(ST_BIND) (symtab->st_info) == STB_GLOBAL
|| ELFW(ST_BIND) (symtab->st_info) == STB_WEAK)
&& __glibc_likely (!dl_symbol_visibility_binds_local_p (symtab))
&& ELFW(ST_TYPE) (symtab->st_info) != STT_TLS
&& (symtab->st_shndx != SHN_UNDEF
|| symtab->st_value != 0)
&& DL_ADDR_SYM_MATCH (match, symtab, matchsym, addr)
&& symtab->st_name < strtabsize)
matchsym = (ElfW(Sym) *) symtab;
}
if (mapp)
*mapp = match;
if (symbolp)
*symbolp = matchsym;
if (matchsym)
{
/* We found a symbol close by. Fill in its name and exact
address. */
lookup_t matchl = LOOKUP_VALUE (match);
info->dli_sname = strtab + matchsym->st_name;
info->dli_saddr = DL_SYMBOL_ADDRESS (matchl, matchsym);
}
else
{
/* No symbol matches. We return only the containing object. */
info->dli_sname = NULL;
info->dli_saddr = NULL;
}
}
int
_dl_addr (const void *address, Dl_info *info,
struct link_map **mapp, const ElfW(Sym) **symbolp)
{
const ElfW(Addr) addr = DL_LOOKUP_ADDRESS (address);
int result = 0;
/* Protect against concurrent loads and unloads. */
__rtld_lock_lock_recursive (GL(dl_load_lock));
struct link_map *l = _dl_find_dso_for_object (addr);
if (l)
{
determine_info (addr, l, info, mapp, symbolp);
result = 1;
}
__rtld_lock_unlock_recursive (GL(dl_load_lock));
return result;
}
libc_hidden_def (_dl_addr)
|
