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-rw-r--r--elf/dl-lookup.c103
1 files changed, 43 insertions, 60 deletions
diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
index 1049639..0674253 100644
--- a/elf/dl-lookup.c
+++ b/elf/dl-lookup.c
@@ -18,27 +18,48 @@ not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <stddef.h>
-#include <libelf.h>
#include <link.h>
#include <assert.h>
+
+/* This is the hashing function specified by the ELF ABI. */
+static inline unsigned
+_dl_elf_hash (const char *name)
+{
+ unsigned long int hash = 0;
+ while (*name != '\0')
+ {
+ unsigned long int hi;
+ hash = (hash << 4) + *name++;
+ hi = hash & 0xf0000000;
+ if (hi != 0)
+ {
+ hash ^= hi >> 24;
+ /* The ELF ABI says `hash &= ~hi', but this is equivalent
+ in this case and on some machines one insn instead of two. */
+ hash ^= hi;
+ }
+ }
+ return hash;
+}
+
/* Search loaded objects' symbol tables for a definition of the symbol
UNDEF_NAME. The chosen value can't be RELOC_ADDR. If NOPLT is nonzero,
then a PLT entry cannot satisfy the reference; some different binding
must be found. */
-Elf32_Addr
-_dl_lookup_symbol (const char *undef_name, const Elf32_Sym **ref,
+ElfW(Addr)
+_dl_lookup_symbol (const char *undef_name, const ElfW(Sym) **ref,
struct link_map *symbol_scope[2],
const char *reference_name,
- Elf32_Addr reloc_addr,
+ ElfW(Addr) reloc_addr,
int noplt)
{
- unsigned long int hash = elf_hash (undef_name);
+ const unsigned long int hash = _dl_elf_hash (undef_name);
struct
{
- Elf32_Addr a;
- const Elf32_Sym *s;
+ ElfW(Addr) a;
+ const ElfW(Sym) *s;
} weak_value = { 0, NULL };
size_t i;
struct link_map **scope, *map;
@@ -48,9 +69,9 @@ _dl_lookup_symbol (const char *undef_name, const Elf32_Sym **ref,
if (*scope)
for (i = 0; i < (*scope)->l_nsearchlist; ++i)
{
- const Elf32_Sym *symtab;
+ const ElfW(Sym) *symtab;
const char *strtab;
- Elf32_Word symidx;
+ ElfW(Word) symidx;
map = (*scope)->l_searchlist[i];
@@ -63,7 +84,7 @@ _dl_lookup_symbol (const char *undef_name, const Elf32_Sym **ref,
symidx != STN_UNDEF;
symidx = map->l_chain[symidx])
{
- const Elf32_Sym *sym = &symtab[symidx];
+ const ElfW(Sym) *sym = &symtab[symidx];
if (sym->st_value == 0 || /* No value. */
/* Cannot resolve to the location being filled in. */
@@ -71,7 +92,7 @@ _dl_lookup_symbol (const char *undef_name, const Elf32_Sym **ref,
(noplt && sym->st_shndx == SHN_UNDEF)) /* Reject PLT. */
continue;
- switch (ELF32_ST_TYPE (sym->st_info))
+ switch (ELFW(ST_TYPE) (sym->st_info))
{
case STT_NOTYPE:
case STT_FUNC:
@@ -86,7 +107,7 @@ _dl_lookup_symbol (const char *undef_name, const Elf32_Sym **ref,
/* Not the symbol we are looking for. */
continue;
- switch (ELF32_ST_BIND (sym->st_info))
+ switch (ELFW(ST_BIND) (sym->st_info))
{
case STB_GLOBAL:
/* Global definition. Just what we need. */
@@ -108,41 +129,15 @@ _dl_lookup_symbol (const char *undef_name, const Elf32_Sym **ref,
}
}
- if (weak_value.s == NULL && ELF32_ST_BIND ((*ref)->st_info) != STB_WEAK)
+ if (weak_value.s == NULL && ELFW(ST_BIND) ((*ref)->st_info) != STB_WEAK)
{
- /* The symbol was not defined by any object in scope. To allow
- access to dynamic linker functionality without using -ldl and
- thereby brining the dynamic linker's symbols into scope, we
- recognize a few magical symbol names and resolve them to the
- addresses of functions inside the dynamic linker. */
-
- struct magic
- {
- unsigned long int hash;
- const char *name;
- Elf32_Addr value;
- };
- static struct magic magic[] =
- {
- { 0xd6a2a5e, "_GNU_libc_dl_open", (Elf32_Addr) &_dl_open },
-/* { 0x69ef845, "_GNU_libc_dl_close", (Elf32_Addr) &_dl_close },*/
- { 0xae4d63c, "_GNU_libc_dl_symbol", (Elf32_Addr) &_dl_symbol_value },
- { 0, NULL, 0 }
- };
- struct magic *m;
-
- for (m = magic; m->hash; ++m)
- if (hash == m->hash && !strcmp (undef_name, m->name))
- return m->value;
-
- {
- const char msg[] = "undefined symbol: ";
- char buf[sizeof msg + strlen (undef_name)];
- memcpy (buf, msg, sizeof msg - 1);
- memcpy (&buf[sizeof msg - 1], undef_name,
- sizeof buf - sizeof msg + 1);
- _dl_signal_error (0, reference_name, buf);
- }
+ /* We could find no value for a strong reference. */
+ const char msg[] = "undefined symbol: ";
+ char buf[sizeof msg + strlen (undef_name)];
+ memcpy (buf, msg, sizeof msg - 1);
+ memcpy (&buf[sizeof msg - 1], undef_name,
+ sizeof buf - sizeof msg + 1);
+ _dl_signal_error (0, reference_name, buf);
}
*ref = weak_value.s;
@@ -155,23 +150,11 @@ _dl_lookup_symbol (const char *undef_name, const Elf32_Sym **ref,
void
_dl_setup_hash (struct link_map *map)
{
- Elf32_Word *hash = (void *) map->l_addr + map->l_info[DT_HASH]->d_un.d_ptr;
- Elf32_Word nchain;
+ ElfW(Word) *hash = (void *) map->l_addr + map->l_info[DT_HASH]->d_un.d_ptr;
+ ElfW(Word) nchain;
map->l_nbuckets = *hash++;
nchain = *hash++;
map->l_buckets = hash;
hash += map->l_nbuckets;
map->l_chain = hash;
}
-
-/* Look up symbol NAME in MAP's scope and return its run-time address. */
-
-Elf32_Addr
-_dl_symbol_value (struct link_map *map, const char *name)
-{
- Elf32_Addr loadbase;
- const Elf32_Sym *ref = NULL;
- struct link_map *scope[2] = { map, NULL };
- loadbase = _dl_lookup_symbol (name, &ref, scope, map->l_name, 0, 0);
- return loadbase + ref->st_value;
-}