diff options
Diffstat (limited to 'elf/dl-lookup.c')
| -rw-r--r-- | elf/dl-lookup.c | 103 |
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; -} |