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get_program_var_addr() must prefer the strong symbol to the weak
one. Search global objects, together with main object and dependencies, for the requested symbol. Move the common code from symlook_default() into new helper symlook_global(), and use it both in symlook_global() and get_program_var_addr(). Supply lock state to get_program_var_addr(). Reviewed by: kan Tested by: Mykola Dzham <i levsha me>
This commit is contained in:
Konstantin Belousov
parent
b15aff0da5
commit
bf390c1fbd
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=217223
@ -103,7 +103,7 @@ static void unload_filtees(Obj_Entry *);
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static int load_needed_objects(Obj_Entry *, int);
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static int load_preload_objects(void);
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static Obj_Entry *load_object(const char *, const Obj_Entry *, int);
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static void map_stacks_exec(void);
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static void map_stacks_exec(RtldLockState *);
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static Obj_Entry *obj_from_addr(const void *);
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static void objlist_call_fini(Objlist *, Obj_Entry *, RtldLockState *);
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static void objlist_call_init(Objlist *, RtldLockState *);
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@ -119,9 +119,10 @@ static int rtld_dirname(const char *, char *);
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static int rtld_dirname_abs(const char *, char *);
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static void rtld_exit(void);
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static char *search_library_path(const char *, const char *);
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static const void **get_program_var_addr(const char *);
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static const void **get_program_var_addr(const char *, RtldLockState *);
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static void set_program_var(const char *, const void *);
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static int symlook_default(SymLook *, const Obj_Entry *refobj);
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static int symlook_global(SymLook *, DoneList *);
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static void symlook_init_from_req(SymLook *, const SymLook *);
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static int symlook_list(SymLook *, const Objlist *, DoneList *);
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static int symlook_needed(SymLook *, const Needed_Entry *, DoneList *);
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@ -528,7 +529,7 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
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r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
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map_stacks_exec();
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map_stacks_exec(NULL);
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wlock_acquire(rtld_bind_lock, &lockstate);
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objlist_call_init(&initlist, &lockstate);
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@ -2129,12 +2130,18 @@ dllockinit(void *context,
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void *
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dlopen(const char *name, int mode)
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{
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RtldLockState lockstate;
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int lo_flags;
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LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
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ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
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if (ld_tracing != NULL)
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environ = (char **)*get_program_var_addr("environ");
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if (ld_tracing != NULL) {
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rlock_acquire(rtld_bind_lock, &lockstate);
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if (setjmp(lockstate.env) != 0)
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lock_upgrade(rtld_bind_lock, &lockstate);
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environ = (char **)*get_program_var_addr("environ", &lockstate);
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lock_release(rtld_bind_lock, &lockstate);
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}
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lo_flags = RTLD_LO_DLOPEN;
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if (mode & RTLD_NODELETE)
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lo_flags |= RTLD_LO_NODELETE;
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@ -2220,7 +2227,7 @@ dlopen_object(const char *name, Obj_Entry *refobj, int lo_flags, int mode)
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name);
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GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
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map_stacks_exec();
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map_stacks_exec(&lockstate);
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/* Call the init functions. */
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objlist_call_init(&initlist, &lockstate);
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@ -2779,21 +2786,20 @@ r_debug_state(struct r_debug* rd, struct link_map *m)
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/*
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* Get address of the pointer variable in the main program.
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* Prefer non-weak symbol over the weak one.
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*/
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static const void **
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get_program_var_addr(const char *name)
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get_program_var_addr(const char *name, RtldLockState *lockstate)
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{
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const Obj_Entry *obj;
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SymLook req;
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DoneList donelist;
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symlook_init(&req, name);
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for (obj = obj_main; obj != NULL; obj = obj->next) {
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if (symlook_obj(&req, obj) == 0) {
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return ((const void **)(req.defobj_out->relocbase +
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req.sym_out->st_value));
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}
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}
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return (NULL);
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req.lockstate = lockstate;
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donelist_init(&donelist);
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if (symlook_global(&req, &donelist) != 0)
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return (NULL);
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return ((const void **)(req.defobj_out->relocbase + req.sym_out->st_value));
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}
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/*
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@ -2806,12 +2812,54 @@ set_program_var(const char *name, const void *value)
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{
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const void **addr;
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if ((addr = get_program_var_addr(name)) != NULL) {
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if ((addr = get_program_var_addr(name, NULL)) != NULL) {
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dbg("\"%s\": *%p <-- %p", name, addr, value);
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*addr = value;
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}
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}
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/*
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* Search the global objects, including dependencies and main object,
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* for the given symbol.
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*/
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static int
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symlook_global(SymLook *req, DoneList *donelist)
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{
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SymLook req1;
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const Objlist_Entry *elm;
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int res;
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symlook_init_from_req(&req1, req);
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/* Search all objects loaded at program start up. */
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if (req->defobj_out == NULL ||
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ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
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res = symlook_list(&req1, &list_main, donelist);
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if (res == 0 && (req->defobj_out == NULL ||
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ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
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req->sym_out = req1.sym_out;
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req->defobj_out = req1.defobj_out;
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assert(req->defobj_out != NULL);
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}
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}
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/* Search all DAGs whose roots are RTLD_GLOBAL objects. */
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STAILQ_FOREACH(elm, &list_global, link) {
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if (req->defobj_out != NULL &&
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ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
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break;
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res = symlook_list(&req1, &elm->obj->dagmembers, donelist);
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if (res == 0 && (req->defobj_out == NULL ||
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ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
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req->sym_out = req1.sym_out;
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req->defobj_out = req1.defobj_out;
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assert(req->defobj_out != NULL);
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}
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}
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return (req->sym_out != NULL ? 0 : ESRCH);
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}
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/*
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* Given a symbol name in a referencing object, find the corresponding
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* definition of the symbol. Returns a pointer to the symbol, or NULL if
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@ -2822,13 +2870,10 @@ static int
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symlook_default(SymLook *req, const Obj_Entry *refobj)
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{
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DoneList donelist;
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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const Objlist_Entry *elm;
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SymLook req1;
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int res;
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def = NULL;
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defobj = NULL;
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donelist_init(&donelist);
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symlook_init_from_req(&req1, req);
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@ -2836,46 +2881,25 @@ symlook_default(SymLook *req, const Obj_Entry *refobj)
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if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
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res = symlook_obj(&req1, refobj);
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if (res == 0) {
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def = req1.sym_out;
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defobj = req1.defobj_out;
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assert(defobj != NULL);
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req->sym_out = req1.sym_out;
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req->defobj_out = req1.defobj_out;
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assert(req->defobj_out != NULL);
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}
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}
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/* Search all objects loaded at program start up. */
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if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
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res = symlook_list(&req1, &list_main, &donelist);
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if (res == 0 &&
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(def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
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def = req1.sym_out;
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defobj = req1.defobj_out;
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assert(defobj != NULL);
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}
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}
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/* Search all DAGs whose roots are RTLD_GLOBAL objects. */
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STAILQ_FOREACH(elm, &list_global, link) {
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if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
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break;
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res = symlook_list(&req1, &elm->obj->dagmembers, &donelist);
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if (res == 0 &&
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(def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
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def = req1.sym_out;
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defobj = req1.defobj_out;
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assert(defobj != NULL);
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}
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}
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symlook_global(req, &donelist);
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/* Search all dlopened DAGs containing the referencing object. */
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STAILQ_FOREACH(elm, &refobj->dldags, link) {
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if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
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if (req->sym_out != NULL &&
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ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
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break;
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res = symlook_list(&req1, &elm->obj->dagmembers, &donelist);
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if (res == 0 &&
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(def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
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def = req1.sym_out;
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defobj = req1.defobj_out;
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assert(defobj != NULL);
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if (res == 0 && (req->sym_out == NULL ||
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ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
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req->sym_out = req1.sym_out;
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req->defobj_out = req1.defobj_out;
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assert(req->defobj_out != NULL);
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}
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}
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@ -2884,22 +2908,17 @@ symlook_default(SymLook *req, const Obj_Entry *refobj)
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* symbol from there. This is how the application links to
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* dynamic linker services such as dlopen.
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*/
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if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
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if (req->sym_out == NULL ||
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ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
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res = symlook_obj(&req1, &obj_rtld);
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if (res == 0) {
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def = req1.sym_out;
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defobj = req1.defobj_out;
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assert(defobj != NULL);
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req->sym_out = req1.sym_out;
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req->defobj_out = req1.defobj_out;
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assert(req->defobj_out != NULL);
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}
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}
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if (def != NULL) {
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assert(defobj != NULL);
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req->defobj_out = defobj;
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req->sym_out = def;
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return (0);
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}
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return (ESRCH);
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return (req->sym_out != NULL ? 0 : ESRCH);
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}
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static int
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@ -3900,14 +3919,14 @@ _rtld_get_stack_prot(void)
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}
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static void
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map_stacks_exec(void)
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map_stacks_exec(RtldLockState *lockstate)
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{
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void (*thr_map_stacks_exec)(void);
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if ((max_stack_flags & PF_X) == 0 || (stack_prot & PROT_EXEC) != 0)
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return;
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thr_map_stacks_exec = (void (*)(void))(uintptr_t)
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get_program_var_addr("__pthread_map_stacks_exec");
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get_program_var_addr("__pthread_map_stacks_exec", lockstate);
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if (thr_map_stacks_exec != NULL) {
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stack_prot |= PROT_EXEC;
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thr_map_stacks_exec();
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