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-rw-r--r--elf/dl-lookup.c211
1 files changed, 137 insertions, 74 deletions
diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
index f35bbbe967..717ac83f7a 100644
--- a/elf/dl-lookup.c
+++ b/elf/dl-lookup.c
@@ -23,6 +23,13 @@
#include <string.h>
+struct sym_val
+ {
+ ElfW(Addr) a;
+ const ElfW(Sym) *s;
+ };
+
+
/* This is the hashing function specified by the ELF ABI. */
static inline unsigned
_dl_elf_hash (const char *name)
@@ -44,6 +51,90 @@ _dl_elf_hash (const char *name)
return hash;
}
+
+/* Inner part of the lookup functions. */
+static inline ElfW(Addr)
+do_lookup (const char *undef_name, unsigned long int hash,
+ const ElfW(Sym) **ref, struct sym_val *result,
+ struct link_map *list[], size_t i, size_t n,
+ const char *reference_name, struct link_map *skip, int flags)
+{
+ struct link_map *map;
+
+ for (; i < n; ++i)
+ {
+ const ElfW(Sym) *symtab;
+ const char *strtab;
+ ElfW(Symndx) symidx;
+
+ map = list[i];
+
+ /* Here come the extra test needed for `_dl_lookup_symbol_skip'. */
+ if (skip != NULL && map == skip)
+ continue;
+
+ /* Don't search the executable when resolving a copy reloc. */
+ if (flags & DL_LOOKUP_NOEXEC && map->l_type == lt_executable)
+ continue;
+
+ symtab = ((void *) map->l_addr + map->l_info[DT_SYMTAB]->d_un.d_ptr);
+ strtab = ((void *) map->l_addr + map->l_info[DT_STRTAB]->d_un.d_ptr);
+
+ /* Search the appropriate hash bucket in this object's symbol table
+ for a definition for the same symbol name. */
+ for (symidx = map->l_buckets[hash % map->l_nbuckets];
+ symidx != STN_UNDEF;
+ symidx = map->l_chain[symidx])
+ {
+ const ElfW(Sym) *sym = &symtab[symidx];
+
+ if (sym->st_value == 0 || /* No value. */
+ ((flags & DL_LOOKUP_NOPLT) != 0 /* Reject PLT entry. */
+ && sym->st_shndx == SHN_UNDEF))
+ continue;
+
+ switch (ELFW(ST_TYPE) (sym->st_info))
+ {
+ case STT_NOTYPE:
+ case STT_FUNC:
+ case STT_OBJECT:
+ break;
+ default:
+ /* Not a code/data definition. */
+ continue;
+ }
+
+ if (sym != *ref && strcmp (strtab + sym->st_name, undef_name))
+ /* Not the symbol we are looking for. */
+ continue;
+
+ switch (ELFW(ST_BIND) (sym->st_info))
+ {
+ case STB_GLOBAL:
+ /* Global definition. Just what we need. */
+ result->s = sym;
+ result->a = map->l_addr;
+ return 1;
+ case STB_WEAK:
+ /* Weak definition. Use this value if we don't find
+ another. */
+ if (! result->s)
+ {
+ result->s = sym;
+ result->a = map->l_addr;
+ }
+ break;
+ default:
+ /* Local symbols are ignored. */
+ break;
+ }
+ }
+ }
+
+ /* We have not found anything until now. */
+ return 0;
+}
+
/* Search loaded objects' symbol tables for a definition of the symbol
UNDEF_NAME. FLAGS is a set of flags. If DL_LOOKUP_NOEXEC is set,
then don't search the executable for a definition; this used for
@@ -57,82 +148,17 @@ _dl_lookup_symbol (const char *undef_name, const ElfW(Sym) **ref,
int flags)
{
const unsigned long int hash = _dl_elf_hash (undef_name);
- struct
- {
- ElfW(Addr) a;
- const ElfW(Sym) *s;
- } weak_value = { 0, NULL };
- size_t i;
- struct link_map **scope, *map;
+ struct sym_val current_value = { 0, NULL };
+ struct link_map **scope;
/* Search the relevant loaded objects for a definition. */
for (scope = symbol_scope; *scope; ++scope)
- for (i = 0; i < (*scope)->l_nsearchlist; ++i)
- {
- const ElfW(Sym) *symtab;
- const char *strtab;
- ElfW(Symndx) symidx;
-
- map = (*scope)->l_searchlist[i];
-
- /* Don't search the executable when resolving a copy reloc. */
- if (flags & DL_LOOKUP_NOEXEC && map->l_type == lt_executable)
- continue;
-
- symtab = ((void *) map->l_addr + map->l_info[DT_SYMTAB]->d_un.d_ptr);
- strtab = ((void *) map->l_addr + map->l_info[DT_STRTAB]->d_un.d_ptr);
-
- /* Search the appropriate hash bucket in this object's symbol table
- for a definition for the same symbol name. */
- for (symidx = map->l_buckets[hash % map->l_nbuckets];
- symidx != STN_UNDEF;
- symidx = map->l_chain[symidx])
- {
- const ElfW(Sym) *sym = &symtab[symidx];
-
- if (sym->st_value == 0 || /* No value. */
- ((flags & DL_LOOKUP_NOPLT) != 0 /* Reject PLT entry. */
- && sym->st_shndx == SHN_UNDEF))
- continue;
-
- switch (ELFW(ST_TYPE) (sym->st_info))
- {
- case STT_NOTYPE:
- case STT_FUNC:
- case STT_OBJECT:
- break;
- default:
- /* Not a code/data definition. */
- continue;
- }
-
- if (sym != *ref && strcmp (strtab + sym->st_name, undef_name))
- /* Not the symbol we are looking for. */
- continue;
+ if (do_lookup (undef_name, hash, ref, &current_value,
+ (*scope)->l_searchlist, 0, (*scope)->l_nsearchlist,
+ reference_name, NULL, flags))
+ break;
- switch (ELFW(ST_BIND) (sym->st_info))
- {
- case STB_GLOBAL:
- /* Global definition. Just what we need. */
- *ref = sym;
- return map->l_addr;
- case STB_WEAK:
- /* Weak definition. Use this value if we don't find
- another. */
- if (! weak_value.s)
- {
- weak_value.s = sym;
- weak_value.a = map->l_addr;
- }
- break;
- default:
- /* Local symbols are ignored. */
- break;
- }
- }
- }
-
- if (weak_value.s == NULL &&
+ if (current_value.s == NULL &&
(*ref == NULL || ELFW(ST_BIND) ((*ref)->st_info) != STB_WEAK))
{
/* We could find no value for a strong reference. */
@@ -144,8 +170,45 @@ _dl_lookup_symbol (const char *undef_name, const ElfW(Sym) **ref,
_dl_signal_error (0, reference_name, buf);
}
- *ref = weak_value.s;
- return weak_value.a;
+ *ref = current_value.s;
+ return current_value.a;
+}
+
+
+/* This function is nearly the same as `_dl_lookup_symbol' but it
+ skips in the first list all objects until SKIP_MAP is found. I.e.,
+ it only considers objects which were loaded after the described
+ object. If there are more search lists the object described by
+ SKIP_MAP is only skipped. */
+ElfW(Addr)
+_dl_lookup_symbol_skip (const char *undef_name, const ElfW(Sym) **ref,
+ struct link_map *symbol_scope[],
+ const char *reference_name,
+ struct link_map *skip_map,
+ int flags)
+{
+ int found_entry = 0;
+ const unsigned long int hash = _dl_elf_hash (undef_name);
+ struct sym_val current_value = { 0, NULL };
+ struct link_map **scope;
+ size_t i;
+
+ /* Search the relevant loaded objects for a definition. */
+ scope = symbol_scope;
+ for (i = 0; (*scope)->l_dupsearchlist[i] != skip_map; ++i)
+ assert (i < (*scope)->l_ndupsearchlist);
+
+ if (! do_lookup (undef_name, hash, ref, &current_value,
+ (*scope)->l_dupsearchlist, i, (*scope)->l_ndupsearchlist,
+ reference_name, skip_map, flags))
+ while (*++scope)
+ if (do_lookup (undef_name, hash, ref, &current_value,
+ (*scope)->l_dupsearchlist, 0, (*scope)->l_ndupsearchlist,
+ reference_name, skip_map, flags))
+ break;
+
+ *ref = current_value.s;
+ return current_value.a;
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-11 06:42:23 +0000