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Simplify the logic in find_symdef().

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This commit is contained in:
John Polstra 1999-08-30 01:24:08 +00:00
parent 252b86ac0b
commit 6bd9374580
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=50606
1 changed files with 41 additions and 45 deletions
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86
libexec/rtld-elf/rtld.c
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@ -685,11 +685,10 @@ find_symdef(unsigned long symnum, const Obj_Entry *refobj,
const Obj_Entry **defobj_out, bool in_plt)
{
const Elf_Sym *ref;
const Elf_Sym *strongdef;
const Elf_Sym *weakdef;
const Elf_Sym *def;
const Elf_Sym *symp;
const Obj_Entry *obj;
const Obj_Entry *strongobj;
const Obj_Entry *weakobj;
const Obj_Entry *defobj;
const char *name;
unsigned long hash;
@ -698,71 +697,68 @@ find_symdef(unsigned long symnum, const Obj_Entry *refobj,
hash = elf_hash(name);
if (refobj->symbolic) { /* Look first in the referencing object */
const Elf_Sym *def = symlook_obj(name, hash, refobj, in_plt);
if (def != NULL) {
if ((symp = symlook_obj(name, hash, refobj, in_plt)) != NULL) {
*defobj_out = refobj;
return def;
return symp;
}
}
/*
* Look in all loaded objects. Skip the referencing object, if
* we have already searched it. We keep track of the first weak
* definition and the first strong definition we encounter. If
* we find a strong definition we stop searching, because there
* won't be anything better than that.
* Look in all loaded objects. Skip the referencing object,
* if we have already searched it. We remember the first weak
* definition we encounter, but we keep searching for a strong
* definition. If we find a strong definition we stop searching,
* because there won't be anything better than that.
*/
strongdef = weakdef = NULL;
strongobj = weakobj = NULL;
def = NULL;
defobj = NULL;
for (obj = obj_list; obj != NULL; obj = obj->next) {
if (obj != refobj || !refobj->symbolic) {
const Elf_Sym *def = symlook_obj(name, hash, obj, in_plt);
if (def != NULL) {
if (ELF_ST_BIND(def->st_info) == STB_WEAK) {
if (weakdef == NULL) {
weakdef = def;
weakobj = obj;
}
} else {
strongdef = def;
strongobj = obj;
break; /* We are done. */
if (obj == refobj && refobj->symbolic)
continue;
if ((symp = symlook_obj(name, hash, obj, in_plt)) != NULL) {
if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) {
def = symp;
defobj = obj;
if (ELF_ST_BIND(def->st_info) != STB_WEAK) {
*defobj_out = defobj;
return def;
}
}
}
}
/*
* If we still don't have a strong definition, search the dynamic
* We still don't have a strong definition. Search the dynamic
* linker itself, and possibly resolve the symbol from there.
* This is how the application links to dynamic linker services
* such as dlopen. Only the values listed in the "exports" array
* can be resolved from the dynamic linker.
*/
if (strongdef == NULL) {
const Elf_Sym *def = symlook_obj(name, hash, &obj_rtld, in_plt);
if (def != NULL && is_exported(def)) {
if (ELF_ST_BIND(def->st_info) == STB_WEAK) {
if (weakdef == NULL) {
weakdef = def;
weakobj = &obj_rtld;
}
} else {
strongdef = def;
strongobj = &obj_rtld;
if ((symp = symlook_obj(name, hash, &obj_rtld, in_plt)) != NULL &&
is_exported(symp)) {
if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) {
def = symp;
defobj = &obj_rtld;
if (ELF_ST_BIND(def->st_info) != STB_WEAK) {
*defobj_out = defobj;
return def;
}
}
}
if (strongdef != NULL) {
*defobj_out = strongobj;
return strongdef;
}
if (weakdef != NULL) {
*defobj_out = weakobj;
return weakdef;
/*
* We didn't find a strong definition. Accept a weak definition
* if we found one.
*/
if (def != NULL) {
*defobj_out = defobj;
return def;
}
/*
* We found no definition. If the reference is weak, treat the
* symbol as having the value zero.
*/
if (ELF_ST_BIND(ref->st_info) == STB_WEAK) {
*defobj_out = obj_main;
return &sym_zero;