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6c03c2cf27
Reject SHN_UNDEF defns iff NOPLT is nonzero. * elf/link.h (_dl_lookup_symbol): Update prototype and comment. * elf/dl-runtime.c (fixup): Pass 1 to _dl_lookup_symbol for NOPLT. * elf/dlsym.c (dlsym): Pass 0. * elf/rtld.c (dl_main): Likewise. * elf/dl-reloc.c (_dl_relocate_object: resolve): Second arg R_OFFSET replaced with NOPLT flag. Pass it through to _dl_lookup_symbol. * elf/do-rel.h (elf_dynamic_do_rel): Update prototype of RESOLVE arg. Pass `elf_machine_pltrel_p (R->r_type)' result as NOPLT flag value. * sysdeps/i386/dl-machine.h (elf_machine_pltrel_p): New macro. * sysdeps/m68k/dl-machine.h (elf_machine_pltrel_p): Likewise. * sysdeps/stub/dl-machine.h (elf_machine_pltrel_p): Likewise.
128 lines
3.7 KiB
C
128 lines
3.7 KiB
C
/* Look up a symbol in the loaded objects.
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Copyright (C) 1995, 1996 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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#include <stddef.h>
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#include <libelf.h>
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#include <link.h>
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#include <assert.h>
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/* Search loaded objects' symbol tables for a definition of the symbol
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UNDEF_NAME. If NOPLT is nonzero, then a PLT entry cannot satisfy the
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reference; some different binding must be found. */
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Elf32_Addr
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_dl_lookup_symbol (const char *undef_name, const Elf32_Sym **ref,
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struct link_map *symbol_scope,
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const char *reference_name,
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int noplt)
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{
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unsigned long int hash = elf_hash (undef_name);
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struct link_map *map;
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struct
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{
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Elf32_Addr a;
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const Elf32_Sym *s;
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} weak_value = { 0, NULL };
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/* Search the relevant loaded objects for a definition. */
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for (map = symbol_scope; map; map = map->l_next)
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{
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const Elf32_Sym *symtab;
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const char *strtab;
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Elf32_Word symidx;
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symtab = ((void *) map->l_addr + map->l_info[DT_SYMTAB]->d_un.d_ptr);
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strtab = ((void *) map->l_addr + map->l_info[DT_STRTAB]->d_un.d_ptr);
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/* Search the appropriate hash bucket in this object's symbol table
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for a definition for the same symbol name. */
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for (symidx = map->l_buckets[hash % map->l_nbuckets];
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symidx != STN_UNDEF;
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symidx = map->l_chain[symidx])
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{
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const Elf32_Sym *sym = &symtab[symidx];
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if (sym->st_value == 0 || /* No value. */
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(noplt && sym->st_shndx == SHN_UNDEF)) /* Unwanted PLT entry. */
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continue;
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switch (ELF32_ST_TYPE (sym->st_info))
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{
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case STT_NOTYPE:
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case STT_FUNC:
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case STT_OBJECT:
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break;
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default:
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/* Not a code/data definition. */
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continue;
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}
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if (sym != *ref && strcmp (strtab + sym->st_name, undef_name))
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/* Not the symbol we are looking for. */
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continue;
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switch (ELF32_ST_BIND (sym->st_info))
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{
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case STB_GLOBAL:
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/* Global definition. Just what we need. */
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*ref = sym;
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return map->l_addr;
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case STB_WEAK:
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/* Weak definition. Use this value if we don't find another. */
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if (! weak_value.s)
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{
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weak_value.s = sym;
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weak_value.a = map->l_addr;
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}
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break;
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default:
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/* Local symbols are ignored. */
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break;
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}
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}
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}
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if (weak_value.s == NULL && ELF32_ST_BIND ((*ref)->st_info) != STB_WEAK)
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{
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const char msg[] = "undefined symbol: ";
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char buf[sizeof msg + strlen (undef_name)];
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memcpy (buf, msg, sizeof msg - 1);
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memcpy (&buf[sizeof msg - 1], undef_name, sizeof buf - sizeof msg + 1);
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_dl_signal_error (0, reference_name, buf);
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}
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*ref = weak_value.s;
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return weak_value.a;
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}
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/* Cache the location of MAP's hash table. */
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void
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_dl_setup_hash (struct link_map *map)
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{
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Elf32_Word *hash = (void *) map->l_addr + map->l_info[DT_HASH]->d_un.d_ptr;
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Elf32_Word nchain;
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map->l_nbuckets = *hash++;
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nchain = *hash++;
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map->l_buckets = hash;
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hash += map->l_nbuckets;
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map->l_chain = hash;
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}
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