139 lines
4.3 KiB
C
139 lines
4.3 KiB
C
/* Locate the shared object symbol nearest a given address.
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Copyright (C) 1996-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <dlfcn.h>
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#include <stddef.h>
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#include <ldsodefs.h>
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static inline void
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__attribute ((always_inline))
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determine_info (const ElfW(Addr) addr, struct link_map *match, Dl_info *info,
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struct link_map **mapp, const ElfW(Sym) **symbolp)
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{
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/* Now we know what object the address lies in. */
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info->dli_fname = match->l_name;
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info->dli_fbase = (void *) match->l_map_start;
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/* If this is the main program the information is incomplete. */
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if (__builtin_expect (match->l_name[0], 'a') == '\0'
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&& match->l_type == lt_executable)
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info->dli_fname = _dl_argv[0];
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const ElfW(Sym) *symtab
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= (const ElfW(Sym) *) D_PTR (match, l_info[DT_SYMTAB]);
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const char *strtab = (const char *) D_PTR (match, l_info[DT_STRTAB]);
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ElfW(Word) strtabsize = match->l_info[DT_STRSZ]->d_un.d_val;
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const ElfW(Sym) *matchsym = NULL;
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if (match->l_info[ELF_MACHINE_GNU_HASH_ADDRIDX] != NULL)
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{
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/* We look at all symbol table entries referenced by the hash
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table. */
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for (Elf_Symndx bucket = 0; bucket < match->l_nbuckets; ++bucket)
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{
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Elf32_Word symndx = match->l_gnu_buckets[bucket];
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if (symndx != 0)
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{
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const Elf32_Word *hasharr = &match->l_gnu_chain_zero[symndx];
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do
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{
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/* The hash table never references local symbols so
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we can omit that test here. */
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symndx = ELF_MACHINE_HASH_SYMIDX (match, hasharr);
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if ((symtab[symndx].st_shndx != SHN_UNDEF
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|| symtab[symndx].st_value != 0)
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&& symtab[symndx].st_shndx != SHN_ABS
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&& ELFW(ST_TYPE) (symtab[symndx].st_info) != STT_TLS
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&& DL_ADDR_SYM_MATCH (match, &symtab[symndx],
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matchsym, addr)
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&& symtab[symndx].st_name < strtabsize)
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matchsym = (ElfW(Sym) *) &symtab[symndx];
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}
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while ((*hasharr++ & 1u) == 0);
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}
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}
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}
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else if (match->l_info[DT_HASH] != NULL)
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{
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const ElfW (Sym) *symtabend
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= (symtab + ((Elf_Symndx *) D_PTR (match, l_info[DT_HASH]))[1]);
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for (; (void *) symtab < (void *) symtabend; ++symtab)
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if ((ELFW(ST_BIND) (symtab->st_info) == STB_GLOBAL
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|| ELFW(ST_BIND) (symtab->st_info) == STB_WEAK)
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&& __glibc_likely (!dl_symbol_visibility_binds_local_p (symtab))
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&& ELFW(ST_TYPE) (symtab->st_info) != STT_TLS
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&& (symtab->st_shndx != SHN_UNDEF
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|| symtab->st_value != 0)
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&& symtab->st_shndx != SHN_ABS
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&& DL_ADDR_SYM_MATCH (match, symtab, matchsym, addr)
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&& symtab->st_name < strtabsize)
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matchsym = (ElfW(Sym) *) symtab;
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}
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/* In the absence of a hash table, treat the object as if it has no symbol.
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*/
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if (mapp)
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*mapp = match;
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if (symbolp)
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*symbolp = matchsym;
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if (matchsym)
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{
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/* We found a symbol close by. Fill in its name and exact
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address. */
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lookup_t matchl = LOOKUP_VALUE (match);
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info->dli_sname = strtab + matchsym->st_name;
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info->dli_saddr = DL_SYMBOL_ADDRESS (matchl, matchsym);
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}
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else
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{
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/* No symbol matches. We return only the containing object. */
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info->dli_sname = NULL;
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info->dli_saddr = NULL;
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}
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}
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int
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_dl_addr (const void *address, Dl_info *info,
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struct link_map **mapp, const ElfW(Sym) **symbolp)
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{
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const ElfW(Addr) addr = DL_LOOKUP_ADDRESS (address);
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int result = 0;
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/* Protect against concurrent loads and unloads. */
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__rtld_lock_lock_recursive (GL(dl_load_lock));
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struct link_map *l = _dl_find_dso_for_object (addr);
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if (l)
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{
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determine_info (addr, l, info, mapp, symbolp);
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result = 1;
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}
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__rtld_lock_unlock_recursive (GL(dl_load_lock));
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return result;
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}
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