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a2b08ee5 | 1 | /* Locate the shared object symbol nearest a given address. |
04277e02 | 2 | Copyright (C) 1996-2019 Free Software Foundation, Inc. |
a2b08ee5 UD |
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 | |
41bdb6e2 AJ |
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. | |
a2b08ee5 UD |
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 | |
41bdb6e2 | 13 | Lesser General Public License for more details. |
a2b08ee5 | 14 | |
41bdb6e2 | 15 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ | |
a2b08ee5 | 18 | |
a2b08ee5 | 19 | #include <dlfcn.h> |
a853022c | 20 | #include <stddef.h> |
a42195db | 21 | #include <ldsodefs.h> |
a2b08ee5 UD |
22 | |
23 | ||
2b2596b1 | 24 | static inline void |
ffecd39b UD |
25 | __attribute ((always_inline)) |
26 | determine_info (const ElfW(Addr) addr, struct link_map *match, Dl_info *info, | |
27 | struct link_map **mapp, const ElfW(Sym) **symbolp) | |
a2b08ee5 | 28 | { |
ffecd39b UD |
29 | /* Now we know what object the address lies in. */ |
30 | info->dli_fname = match->l_name; | |
31 | info->dli_fbase = (void *) match->l_map_start; | |
a334319f | 32 | |
ffecd39b UD |
33 | /* If this is the main program the information is incomplete. */ |
34 | if (__builtin_expect (match->l_name[0], 'a') == '\0' | |
35 | && match->l_type == lt_executable) | |
36 | info->dli_fname = _dl_argv[0]; | |
a334319f | 37 | |
ffecd39b UD |
38 | const ElfW(Sym) *symtab |
39 | = (const ElfW(Sym) *) D_PTR (match, l_info[DT_SYMTAB]); | |
40 | const char *strtab = (const char *) D_PTR (match, l_info[DT_STRTAB]); | |
11bf311e | 41 | |
ffecd39b | 42 | ElfW(Word) strtabsize = match->l_info[DT_STRSZ]->d_un.d_val; |
11bf311e | 43 | |
ffecd39b | 44 | const ElfW(Sym) *matchsym = NULL; |
6a5cac49 | 45 | if (match->l_info[ADDRIDX (DT_GNU_HASH)] != NULL) |
32c075e1 | 46 | { |
ffecd39b UD |
47 | /* We look at all symbol table entries referenced by the hash |
48 | table. */ | |
49 | for (Elf_Symndx bucket = 0; bucket < match->l_nbuckets; ++bucket) | |
11bf311e | 50 | { |
ffecd39b UD |
51 | Elf32_Word symndx = match->l_gnu_buckets[bucket]; |
52 | if (symndx != 0) | |
11bf311e | 53 | { |
ffecd39b UD |
54 | const Elf32_Word *hasharr = &match->l_gnu_chain_zero[symndx]; |
55 | ||
56 | do | |
11bf311e | 57 | { |
ffecd39b UD |
58 | /* The hash table never references local symbols so |
59 | we can omit that test here. */ | |
60 | if ((symtab[symndx].st_shndx != SHN_UNDEF | |
61 | || symtab[symndx].st_value != 0) | |
e7feec37 | 62 | && symtab[symndx].st_shndx != SHN_ABS |
ffecd39b UD |
63 | && ELFW(ST_TYPE) (symtab[symndx].st_info) != STT_TLS |
64 | && DL_ADDR_SYM_MATCH (match, &symtab[symndx], | |
65 | matchsym, addr) | |
66 | && symtab[symndx].st_name < strtabsize) | |
67 | matchsym = (ElfW(Sym) *) &symtab[symndx]; | |
68 | ||
69 | ++symndx; | |
11bf311e | 70 | } |
ffecd39b | 71 | while ((*hasharr++ & 1u) == 0); |
11bf311e UD |
72 | } |
73 | } | |
ffecd39b UD |
74 | } |
75 | else | |
76 | { | |
77 | const ElfW(Sym) *symtabend; | |
78 | if (match->l_info[DT_HASH] != NULL) | |
79 | symtabend = (symtab | |
80 | + ((Elf_Symndx *) D_PTR (match, l_info[DT_HASH]))[1]); | |
11bf311e | 81 | else |
ffecd39b UD |
82 | /* There is no direct way to determine the number of symbols in the |
83 | dynamic symbol table and no hash table is present. The ELF | |
84 | binary is ill-formed but what shall we do? Use the beginning of | |
85 | the string table which generally follows the symbol table. */ | |
86 | symtabend = (const ElfW(Sym) *) strtab; | |
87 | ||
88 | for (; (void *) symtab < (void *) symtabend; ++symtab) | |
89 | if ((ELFW(ST_BIND) (symtab->st_info) == STB_GLOBAL | |
90 | || ELFW(ST_BIND) (symtab->st_info) == STB_WEAK) | |
b6084a95 | 91 | && __glibc_likely (!dl_symbol_visibility_binds_local_p (symtab)) |
ffecd39b UD |
92 | && ELFW(ST_TYPE) (symtab->st_info) != STT_TLS |
93 | && (symtab->st_shndx != SHN_UNDEF | |
94 | || symtab->st_value != 0) | |
e7feec37 | 95 | && symtab->st_shndx != SHN_ABS |
ffecd39b UD |
96 | && DL_ADDR_SYM_MATCH (match, symtab, matchsym, addr) |
97 | && symtab->st_name < strtabsize) | |
98 | matchsym = (ElfW(Sym) *) symtab; | |
99 | } | |
32c075e1 | 100 | |
ffecd39b UD |
101 | if (mapp) |
102 | *mapp = match; | |
103 | if (symbolp) | |
104 | *symbolp = matchsym; | |
32c075e1 | 105 | |
ffecd39b UD |
106 | if (matchsym) |
107 | { | |
108 | /* We found a symbol close by. Fill in its name and exact | |
109 | address. */ | |
110 | lookup_t matchl = LOOKUP_VALUE (match); | |
32c075e1 | 111 | |
ffecd39b UD |
112 | info->dli_sname = strtab + matchsym->st_name; |
113 | info->dli_saddr = DL_SYMBOL_ADDRESS (matchl, matchsym); | |
114 | } | |
115 | else | |
116 | { | |
117 | /* No symbol matches. We return only the containing object. */ | |
118 | info->dli_sname = NULL; | |
119 | info->dli_saddr = NULL; | |
120 | } | |
121 | } | |
122 | ||
123 | ||
124 | int | |
ffecd39b UD |
125 | _dl_addr (const void *address, Dl_info *info, |
126 | struct link_map **mapp, const ElfW(Sym) **symbolp) | |
127 | { | |
128 | const ElfW(Addr) addr = DL_LOOKUP_ADDRESS (address); | |
129 | int result = 0; | |
130 | ||
131 | /* Protect against concurrent loads and unloads. */ | |
132 | __rtld_lock_lock_recursive (GL(dl_load_lock)); | |
133 | ||
be179c8a SP |
134 | struct link_map *l = _dl_find_dso_for_object (addr); |
135 | ||
136 | if (l) | |
137 | { | |
138 | determine_info (addr, l, info, mapp, symbolp); | |
139 | result = 1; | |
140 | } | |
a461b147 | 141 | |
a461b147 UD |
142 | __rtld_lock_unlock_recursive (GL(dl_load_lock)); |
143 | ||
144 | return result; | |
a2b08ee5 | 145 | } |
cc7e7a26 | 146 | libc_hidden_def (_dl_addr) |