xref: /dragonfly/libexec/rtld-elf/rtld.c (revision 1847e88f)
1 /*-
2  * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
3  * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>.
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  *
26  * $FreeBSD: src/libexec/rtld-elf/rtld.c,v 1.43.2.15 2003/02/20 20:42:46 kan Exp $
27  * $DragonFly: src/libexec/rtld-elf/rtld.c,v 1.23 2005/05/11 19:47:06 dillon Exp $
28  */
29 
30 /*
31  * Dynamic linker for ELF.
32  *
33  * John Polstra <jdp@polstra.com>.
34  */
35 
36 #ifndef __GNUC__
37 #error "GCC is needed to compile this file"
38 #endif
39 
40 #include <sys/param.h>
41 #include <sys/mman.h>
42 #include <sys/stat.h>
43 #include <sys/resident.h>
44 #include <sys/tls.h>
45 
46 #include <machine/tls.h>
47 
48 #include <dlfcn.h>
49 #include <err.h>
50 #include <errno.h>
51 #include <fcntl.h>
52 #include <stdarg.h>
53 #include <stdio.h>
54 #include <stdlib.h>
55 #include <string.h>
56 #include <unistd.h>
57 
58 #include "debug.h"
59 #include "rtld.h"
60 
61 #define PATH_RTLD	"/usr/libexec/ld-elf.so.2"
62 #define LD_ARY_CACHE	16
63 
64 /* Types. */
65 typedef void (*func_ptr_type)();
66 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg);
67 
68 /*
69  * This structure provides a reentrant way to keep a list of objects and
70  * check which ones have already been processed in some way.
71  */
72 typedef struct Struct_DoneList {
73     const Obj_Entry **objs;		/* Array of object pointers */
74     unsigned int num_alloc;		/* Allocated size of the array */
75     unsigned int num_used;		/* Number of array slots used */
76 } DoneList;
77 
78 /*
79  * Function declarations.
80  */
81 static void die(void);
82 static void digest_dynamic(Obj_Entry *);
83 static const char *_getenv_ld(const char *id);
84 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
85 static Obj_Entry *dlcheck(void *);
86 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *);
87 static bool donelist_check(DoneList *, const Obj_Entry *);
88 static void errmsg_restore(char *);
89 static char *errmsg_save(void);
90 static void *fill_search_info(const char *, size_t, void *);
91 static char *find_library(const char *, const Obj_Entry *);
92 static Obj_Entry *find_object(const char *);
93 static Obj_Entry *find_object2(const char *, int *, struct stat *);
94 static const char *gethints(void);
95 static void init_dag(Obj_Entry *);
96 static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *);
97 static void init_rtld(caddr_t);
98 static void initlist_add_neededs(Needed_Entry *needed, Objlist *list);
99 static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail,
100   Objlist *list);
101 static bool is_exported(const Elf_Sym *);
102 static void linkmap_add(Obj_Entry *);
103 static void linkmap_delete(Obj_Entry *);
104 static int load_needed_objects(Obj_Entry *);
105 static int load_preload_objects(void);
106 static Obj_Entry *load_object(char *);
107 static void lock_check(void);
108 static Obj_Entry *obj_from_addr(const void *);
109 static void objlist_call_fini(Objlist *);
110 static void objlist_call_init(Objlist *);
111 static void objlist_clear(Objlist *);
112 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
113 static void objlist_init(Objlist *);
114 static void objlist_push_head(Objlist *, Obj_Entry *);
115 static void objlist_push_tail(Objlist *, Obj_Entry *);
116 static void objlist_remove(Objlist *, Obj_Entry *);
117 static void objlist_remove_unref(Objlist *);
118 static void *path_enumerate(const char *, path_enum_proc, void *);
119 static int relocate_objects(Obj_Entry *, bool);
120 static int rtld_dirname(const char *, char *);
121 static void rtld_exit(void);
122 static char *search_library_path(const char *, const char *);
123 static const void **get_program_var_addr(const char *name);
124 static void set_program_var(const char *, const void *);
125 static const Elf_Sym *symlook_default(const char *, unsigned long hash,
126   const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt);
127 static const Elf_Sym *symlook_list(const char *, unsigned long,
128   Objlist *, const Obj_Entry **, bool in_plt, DoneList *);
129 static void trace_loaded_objects(Obj_Entry *obj);
130 static void unlink_object(Obj_Entry *);
131 static void unload_object(Obj_Entry *);
132 static void unref_dag(Obj_Entry *);
133 
134 void r_debug_state(struct r_debug*, struct link_map*);
135 
136 /*
137  * Data declarations.
138  */
139 static char *error_message;	/* Message for dlerror(), or NULL */
140 struct r_debug r_debug;		/* for GDB; */
141 static bool trust;		/* False for setuid and setgid programs */
142 static const char *ld_bind_now;	/* Environment variable for immediate binding */
143 static const char *ld_debug;	/* Environment variable for debugging */
144 static const char *ld_library_path; /* Environment variable for search path */
145 static char *ld_preload;	/* Environment variable for libraries to
146 				   load first */
147 static const char *ld_tracing;	/* Called from ldd(1) to print libs */
148 static Obj_Entry *obj_list;	/* Head of linked list of shared objects */
149 static Obj_Entry **obj_tail;	/* Link field of last object in list */
150 static Obj_Entry **preload_tail;
151 static Obj_Entry *obj_main;	/* The main program shared object */
152 static Obj_Entry obj_rtld;	/* The dynamic linker shared object */
153 static unsigned int obj_count;	/* Number of objects in obj_list */
154 static int	ld_resident;	/* Non-zero if resident */
155 static const char *ld_ary[LD_ARY_CACHE];
156 static int	ld_index;
157 static Objlist initlist;
158 
159 static Objlist list_global =	/* Objects dlopened with RTLD_GLOBAL */
160   STAILQ_HEAD_INITIALIZER(list_global);
161 static Objlist list_main =	/* Objects loaded at program startup */
162   STAILQ_HEAD_INITIALIZER(list_main);
163 static Objlist list_fini =	/* Objects needing fini() calls */
164   STAILQ_HEAD_INITIALIZER(list_fini);
165 
166 static LockInfo lockinfo;
167 
168 static Elf_Sym sym_zero;	/* For resolving undefined weak refs. */
169 
170 #define GDB_STATE(s,m)	r_debug.r_state = s; r_debug_state(&r_debug,m);
171 
172 extern Elf_Dyn _DYNAMIC;
173 #pragma weak _DYNAMIC
174 
175 /*
176  * These are the functions the dynamic linker exports to application
177  * programs.  They are the only symbols the dynamic linker is willing
178  * to export from itself.
179  */
180 static func_ptr_type exports[] = {
181     (func_ptr_type) &_rtld_error,
182     (func_ptr_type) &dlclose,
183     (func_ptr_type) &dlerror,
184     (func_ptr_type) &dlopen,
185     (func_ptr_type) &dlsym,
186     (func_ptr_type) &dladdr,
187     (func_ptr_type) &dlinfo,
188 #ifdef __i386__
189     (func_ptr_type) &___tls_get_addr,
190 #endif
191     (func_ptr_type) &__tls_get_addr,
192     (func_ptr_type) &__tls_get_addr_tcb,
193     (func_ptr_type) &_rtld_allocate_tls,
194     (func_ptr_type) &_rtld_free_tls,
195     (func_ptr_type) &_rtld_call_init,
196     NULL
197 };
198 
199 /*
200  * Global declarations normally provided by crt1.  The dynamic linker is
201  * not built with crt1, so we have to provide them ourselves.
202  */
203 char *__progname;
204 char **environ;
205 
206 /*
207  * Globals to control TLS allocation.
208  */
209 size_t tls_last_offset;		/* Static TLS offset of last module */
210 size_t tls_last_size;		/* Static TLS size of last module */
211 size_t tls_static_space;	/* Static TLS space allocated */
212 int tls_dtv_generation = 1;	/* Used to detect when dtv size changes  */
213 int tls_max_index = 1;		/* Largest module index allocated */
214 
215 /*
216  * Fill in a DoneList with an allocation large enough to hold all of
217  * the currently-loaded objects.  Keep this as a macro since it calls
218  * alloca and we want that to occur within the scope of the caller.
219  */
220 #define donelist_init(dlp)					\
221     ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]),	\
222     assert((dlp)->objs != NULL),				\
223     (dlp)->num_alloc = obj_count,				\
224     (dlp)->num_used = 0)
225 
226 static __inline void
227 rlock_acquire(void)
228 {
229     lockinfo.rlock_acquire(lockinfo.thelock);
230     atomic_incr_int(&lockinfo.rcount);
231     lock_check();
232 }
233 
234 static __inline void
235 wlock_acquire(void)
236 {
237     lockinfo.wlock_acquire(lockinfo.thelock);
238     atomic_incr_int(&lockinfo.wcount);
239     lock_check();
240 }
241 
242 static __inline void
243 rlock_release(void)
244 {
245     atomic_decr_int(&lockinfo.rcount);
246     lockinfo.rlock_release(lockinfo.thelock);
247 }
248 
249 static __inline void
250 wlock_release(void)
251 {
252     atomic_decr_int(&lockinfo.wcount);
253     lockinfo.wlock_release(lockinfo.thelock);
254 }
255 
256 /*
257  * Main entry point for dynamic linking.  The first argument is the
258  * stack pointer.  The stack is expected to be laid out as described
259  * in the SVR4 ABI specification, Intel 386 Processor Supplement.
260  * Specifically, the stack pointer points to a word containing
261  * ARGC.  Following that in the stack is a null-terminated sequence
262  * of pointers to argument strings.  Then comes a null-terminated
263  * sequence of pointers to environment strings.  Finally, there is a
264  * sequence of "auxiliary vector" entries.
265  *
266  * The second argument points to a place to store the dynamic linker's
267  * exit procedure pointer and the third to a place to store the main
268  * program's object.
269  *
270  * The return value is the main program's entry point.
271  */
272 
273 func_ptr_type
274 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
275 {
276     Elf_Auxinfo *aux_info[AT_COUNT];
277     int i;
278     int argc;
279     char **argv;
280     char **env;
281     Elf_Auxinfo *aux;
282     Elf_Auxinfo *auxp;
283     const char *argv0;
284     Objlist_Entry *entry;
285     Obj_Entry *obj;
286 
287     ld_index = 0;	/* don't use old env cache in case we are resident */
288 
289     /*
290      * On entry, the dynamic linker itself has not been relocated yet.
291      * Be very careful not to reference any global data until after
292      * init_rtld has returned.  It is OK to reference file-scope statics
293      * and string constants, and to call static and global functions.
294      */
295 
296     /* Find the auxiliary vector on the stack. */
297     argc = *sp++;
298     argv = (char **) sp;
299     sp += argc + 1;	/* Skip over arguments and NULL terminator */
300     env = (char **) sp;
301 
302     /*
303      * If we aren't already resident we have to dig out some more info.
304      * Note that auxinfo does not exist when we are resident.
305      */
306     if (ld_resident == 0) {
307 	while (*sp++ != 0)	/* Skip over environment, and NULL terminator */
308 	    ;
309 	aux = (Elf_Auxinfo *) sp;
310 
311 	/* Digest the auxiliary vector. */
312 	for (i = 0;  i < AT_COUNT;  i++)
313 	    aux_info[i] = NULL;
314 	for (auxp = aux;  auxp->a_type != AT_NULL;  auxp++) {
315 	    if (auxp->a_type < AT_COUNT)
316 		aux_info[auxp->a_type] = auxp;
317 	}
318 
319 	/* Initialize and relocate ourselves. */
320 	assert(aux_info[AT_BASE] != NULL);
321 	init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
322     }
323 
324     __progname = obj_rtld.path;
325     argv0 = argv[0] != NULL ? argv[0] : "(null)";
326     environ = env;
327 
328     trust = (geteuid() == getuid()) && (getegid() == getgid());
329 
330     ld_bind_now = _getenv_ld("LD_BIND_NOW");
331     if (trust) {
332 	ld_debug = _getenv_ld("LD_DEBUG");
333 	ld_library_path = _getenv_ld("LD_LIBRARY_PATH");
334 	ld_preload = (char *)_getenv_ld("LD_PRELOAD");
335     }
336     ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS");
337 
338     if (ld_debug != NULL && *ld_debug != '\0')
339 	debug = 1;
340     dbg("%s is initialized, base address = %p", __progname,
341 	(caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
342     dbg("RTLD dynamic = %p", obj_rtld.dynamic);
343     dbg("RTLD pltgot  = %p", obj_rtld.pltgot);
344 
345     /*
346      * If we are resident we can skip work that we have already done.
347      * Note that the stack is reset and there is no Elf_Auxinfo
348      * when running from a resident image, and the static globals setup
349      * between here and resident_skip will have already been setup.
350      */
351     if (ld_resident)
352 	goto resident_skip1;
353 
354     /*
355      * Load the main program, or process its program header if it is
356      * already loaded.
357      */
358     if (aux_info[AT_EXECFD] != NULL) {	/* Load the main program. */
359 	int fd = aux_info[AT_EXECFD]->a_un.a_val;
360 	dbg("loading main program");
361 	obj_main = map_object(fd, argv0, NULL);
362 	close(fd);
363 	if (obj_main == NULL)
364 	    die();
365     } else {				/* Main program already loaded. */
366 	const Elf_Phdr *phdr;
367 	int phnum;
368 	caddr_t entry;
369 
370 	dbg("processing main program's program header");
371 	assert(aux_info[AT_PHDR] != NULL);
372 	phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
373 	assert(aux_info[AT_PHNUM] != NULL);
374 	phnum = aux_info[AT_PHNUM]->a_un.a_val;
375 	assert(aux_info[AT_PHENT] != NULL);
376 	assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
377 	assert(aux_info[AT_ENTRY] != NULL);
378 	entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
379 	if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
380 	    die();
381     }
382 
383     obj_main->path = xstrdup(argv0);
384     obj_main->mainprog = true;
385 
386     /*
387      * Get the actual dynamic linker pathname from the executable if
388      * possible.  (It should always be possible.)  That ensures that
389      * gdb will find the right dynamic linker even if a non-standard
390      * one is being used.
391      */
392     if (obj_main->interp != NULL &&
393       strcmp(obj_main->interp, obj_rtld.path) != 0) {
394 	free(obj_rtld.path);
395 	obj_rtld.path = xstrdup(obj_main->interp);
396 	__progname = obj_rtld.path;
397     }
398 
399     digest_dynamic(obj_main);
400 
401     linkmap_add(obj_main);
402     linkmap_add(&obj_rtld);
403 
404     /* Link the main program into the list of objects. */
405     *obj_tail = obj_main;
406     obj_tail = &obj_main->next;
407     obj_count++;
408     obj_main->refcount++;
409     /* Make sure we don't call the main program's init and fini functions. */
410     obj_main->init = obj_main->fini = NULL;
411 
412     /* Initialize a fake symbol for resolving undefined weak references. */
413     sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
414     sym_zero.st_shndx = SHN_ABS;
415 
416     dbg("loading LD_PRELOAD libraries");
417     if (load_preload_objects() == -1)
418 	die();
419     preload_tail = obj_tail;
420 
421     dbg("loading needed objects");
422     if (load_needed_objects(obj_main) == -1)
423 	die();
424 
425     /* Make a list of all objects loaded at startup. */
426     for (obj = obj_list;  obj != NULL;  obj = obj->next)
427 	objlist_push_tail(&list_main, obj);
428 
429 resident_skip1:
430 
431     if (ld_tracing) {		/* We're done */
432 	trace_loaded_objects(obj_main);
433 	exit(0);
434     }
435 
436     if (ld_resident)		/* XXX clean this up! */
437 	goto resident_skip2;
438 
439     if (getenv("LD_DUMP_REL_PRE") != NULL) {
440        dump_relocations(obj_main);
441        exit (0);
442     }
443 
444     /* setup TLS for main thread */
445     dbg("initializing initial thread local storage");
446     STAILQ_FOREACH(entry, &list_main, link) {
447 	/*
448 	 * Allocate all the initial objects out of the static TLS
449 	 * block even if they didn't ask for it.
450 	 */
451 	allocate_tls_offset(entry->obj);
452     }
453 
454     tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA;
455 
456     /*
457      * Do not try to allocate the TLS here, let libc do it itself.
458      * (crt1 for the program will call _init_tls())
459      */
460 
461     if (relocate_objects(obj_main,
462 	ld_bind_now != NULL && *ld_bind_now != '\0') == -1)
463 	die();
464 
465     dbg("doing copy relocations");
466     if (do_copy_relocations(obj_main) == -1)
467 	die();
468 
469 resident_skip2:
470 
471     if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) {
472 	if (exec_sys_unregister(-1) < 0) {
473 	    dbg("exec_sys_unregister failed %d\n", errno);
474 	    exit(errno);
475 	}
476 	dbg("exec_sys_unregister success\n");
477 	exit(0);
478     }
479 
480     if (getenv("LD_DUMP_REL_POST") != NULL) {
481        dump_relocations(obj_main);
482        exit (0);
483     }
484 
485     dbg("initializing key program variables");
486     set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
487     set_program_var("environ", env);
488 
489     if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) {
490 	extern void resident_start(void);
491 	ld_resident = 1;
492 	if (exec_sys_register(resident_start) < 0) {
493 	    dbg("exec_sys_register failed %d\n", errno);
494 	    exit(errno);
495 	}
496 	dbg("exec_sys_register success\n");
497 	exit(0);
498     }
499 
500     dbg("initializing thread locks");
501     lockdflt_init(&lockinfo);
502     lockinfo.thelock = lockinfo.lock_create(lockinfo.context);
503 
504     /* Make a list of init functions to call. */
505     objlist_init(&initlist);
506     initlist_add_objects(obj_list, preload_tail, &initlist);
507 
508     r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
509 
510     /*
511      * Do NOT call the initlist here, give libc a chance to set up
512      * the initial TLS segment.  crt1 will then call _rtld_call_init().
513      */
514 
515     dbg("transferring control to program entry point = %p", obj_main->entry);
516 
517     /* Return the exit procedure and the program entry point. */
518     *exit_proc = rtld_exit;
519     *objp = obj_main;
520     return (func_ptr_type) obj_main->entry;
521 }
522 
523 /*
524  * Call the initialization list for dynamically loaded libraries.
525  * (called from crt1.c).
526  */
527 void
528 _rtld_call_init(void)
529 {
530     objlist_call_init(&initlist);
531     wlock_acquire();
532     objlist_clear(&initlist);
533     wlock_release();
534 }
535 
536 Elf_Addr
537 _rtld_bind(Obj_Entry *obj, Elf_Word reloff)
538 {
539     const Elf_Rel *rel;
540     const Elf_Sym *def;
541     const Obj_Entry *defobj;
542     Elf_Addr *where;
543     Elf_Addr target;
544 
545     rlock_acquire();
546     if (obj->pltrel)
547 	rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
548     else
549 	rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
550 
551     where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
552     def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL);
553     if (def == NULL)
554 	die();
555 
556     target = (Elf_Addr)(defobj->relocbase + def->st_value);
557 
558     dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
559       defobj->strtab + def->st_name, basename(obj->path),
560       (void *)target, basename(defobj->path));
561 
562     reloc_jmpslot(where, target);
563     rlock_release();
564     return target;
565 }
566 
567 /*
568  * Error reporting function.  Use it like printf.  If formats the message
569  * into a buffer, and sets things up so that the next call to dlerror()
570  * will return the message.
571  */
572 void
573 _rtld_error(const char *fmt, ...)
574 {
575     static char buf[512];
576     va_list ap;
577 
578     va_start(ap, fmt);
579     vsnprintf(buf, sizeof buf, fmt, ap);
580     error_message = buf;
581     va_end(ap);
582 }
583 
584 /*
585  * Return a dynamically-allocated copy of the current error message, if any.
586  */
587 static char *
588 errmsg_save(void)
589 {
590     return error_message == NULL ? NULL : xstrdup(error_message);
591 }
592 
593 /*
594  * Restore the current error message from a copy which was previously saved
595  * by errmsg_save().  The copy is freed.
596  */
597 static void
598 errmsg_restore(char *saved_msg)
599 {
600     if (saved_msg == NULL)
601 	error_message = NULL;
602     else {
603 	_rtld_error("%s", saved_msg);
604 	free(saved_msg);
605     }
606 }
607 
608 const char *
609 basename(const char *name)
610 {
611     const char *p = strrchr(name, '/');
612     return p != NULL ? p + 1 : name;
613 }
614 
615 static void
616 die(void)
617 {
618     const char *msg = dlerror();
619 
620     if (msg == NULL)
621 	msg = "Fatal error";
622     errx(1, "%s", msg);
623 }
624 
625 /*
626  * Process a shared object's DYNAMIC section, and save the important
627  * information in its Obj_Entry structure.
628  */
629 static void
630 digest_dynamic(Obj_Entry *obj)
631 {
632     const Elf_Dyn *dynp;
633     Needed_Entry **needed_tail = &obj->needed;
634     const Elf_Dyn *dyn_rpath = NULL;
635     int plttype = DT_REL;
636 
637     for (dynp = obj->dynamic;  dynp->d_tag != DT_NULL;  dynp++) {
638 	switch (dynp->d_tag) {
639 
640 	case DT_REL:
641 	    obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
642 	    break;
643 
644 	case DT_RELSZ:
645 	    obj->relsize = dynp->d_un.d_val;
646 	    break;
647 
648 	case DT_RELENT:
649 	    assert(dynp->d_un.d_val == sizeof(Elf_Rel));
650 	    break;
651 
652 	case DT_JMPREL:
653 	    obj->pltrel = (const Elf_Rel *)
654 	      (obj->relocbase + dynp->d_un.d_ptr);
655 	    break;
656 
657 	case DT_PLTRELSZ:
658 	    obj->pltrelsize = dynp->d_un.d_val;
659 	    break;
660 
661 	case DT_RELA:
662 	    obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
663 	    break;
664 
665 	case DT_RELASZ:
666 	    obj->relasize = dynp->d_un.d_val;
667 	    break;
668 
669 	case DT_RELAENT:
670 	    assert(dynp->d_un.d_val == sizeof(Elf_Rela));
671 	    break;
672 
673 	case DT_PLTREL:
674 	    plttype = dynp->d_un.d_val;
675 	    assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
676 	    break;
677 
678 	case DT_SYMTAB:
679 	    obj->symtab = (const Elf_Sym *)
680 	      (obj->relocbase + dynp->d_un.d_ptr);
681 	    break;
682 
683 	case DT_SYMENT:
684 	    assert(dynp->d_un.d_val == sizeof(Elf_Sym));
685 	    break;
686 
687 	case DT_STRTAB:
688 	    obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
689 	    break;
690 
691 	case DT_STRSZ:
692 	    obj->strsize = dynp->d_un.d_val;
693 	    break;
694 
695 	case DT_HASH:
696 	    {
697 		const Elf_Addr *hashtab = (const Elf_Addr *)
698 		  (obj->relocbase + dynp->d_un.d_ptr);
699 		obj->nbuckets = hashtab[0];
700 		obj->nchains = hashtab[1];
701 		obj->buckets = hashtab + 2;
702 		obj->chains = obj->buckets + obj->nbuckets;
703 	    }
704 	    break;
705 
706 	case DT_NEEDED:
707 	    if (!obj->rtld) {
708 		Needed_Entry *nep = NEW(Needed_Entry);
709 		nep->name = dynp->d_un.d_val;
710 		nep->obj = NULL;
711 		nep->next = NULL;
712 
713 		*needed_tail = nep;
714 		needed_tail = &nep->next;
715 	    }
716 	    break;
717 
718 	case DT_PLTGOT:
719 	    obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
720 	    break;
721 
722 	case DT_TEXTREL:
723 	    obj->textrel = true;
724 	    break;
725 
726 	case DT_SYMBOLIC:
727 	    obj->symbolic = true;
728 	    break;
729 
730 	case DT_RPATH:
731 	case DT_RUNPATH:	/* XXX: process separately */
732 	    /*
733 	     * We have to wait until later to process this, because we
734 	     * might not have gotten the address of the string table yet.
735 	     */
736 	    dyn_rpath = dynp;
737 	    break;
738 
739 	case DT_SONAME:
740 	    /* Not used by the dynamic linker. */
741 	    break;
742 
743 	case DT_INIT:
744 	    obj->init = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
745 	    break;
746 
747 	case DT_FINI:
748 	    obj->fini = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
749 	    break;
750 
751 	case DT_DEBUG:
752 	    /* XXX - not implemented yet */
753 	    dbg("Filling in DT_DEBUG entry");
754 	    ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
755 	    break;
756 
757 	case DT_FLAGS:
758 		if (dynp->d_un.d_val & DF_ORIGIN) {
759 		    obj->origin_path = xmalloc(PATH_MAX);
760 		    if (rtld_dirname(obj->path, obj->origin_path) == -1)
761 			die();
762 		}
763 		if (dynp->d_un.d_val & DF_SYMBOLIC)
764 		    obj->symbolic = true;
765 		if (dynp->d_un.d_val & DF_TEXTREL)
766 		    obj->textrel = true;
767 		if (dynp->d_un.d_val & DF_BIND_NOW)
768 		    obj->bind_now = true;
769 		if (dynp->d_un.d_val & DF_STATIC_TLS)
770 		    ;
771 	    break;
772 
773 	default:
774 	    dbg("Ignoring d_tag %d = %#x", dynp->d_tag, dynp->d_tag);
775 	    break;
776 	}
777     }
778 
779     obj->traced = false;
780 
781     if (plttype == DT_RELA) {
782 	obj->pltrela = (const Elf_Rela *) obj->pltrel;
783 	obj->pltrel = NULL;
784 	obj->pltrelasize = obj->pltrelsize;
785 	obj->pltrelsize = 0;
786     }
787 
788     if (dyn_rpath != NULL)
789 	obj->rpath = obj->strtab + dyn_rpath->d_un.d_val;
790 }
791 
792 /*
793  * Process a shared object's program header.  This is used only for the
794  * main program, when the kernel has already loaded the main program
795  * into memory before calling the dynamic linker.  It creates and
796  * returns an Obj_Entry structure.
797  */
798 static Obj_Entry *
799 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
800 {
801     Obj_Entry *obj;
802     const Elf_Phdr *phlimit = phdr + phnum;
803     const Elf_Phdr *ph;
804     int nsegs = 0;
805 
806     obj = obj_new();
807     for (ph = phdr;  ph < phlimit;  ph++) {
808 	switch (ph->p_type) {
809 
810 	case PT_PHDR:
811 	    if ((const Elf_Phdr *)ph->p_vaddr != phdr) {
812 		_rtld_error("%s: invalid PT_PHDR", path);
813 		return NULL;
814 	    }
815 	    obj->phdr = (const Elf_Phdr *) ph->p_vaddr;
816 	    obj->phsize = ph->p_memsz;
817 	    break;
818 
819 	case PT_INTERP:
820 	    obj->interp = (const char *) ph->p_vaddr;
821 	    break;
822 
823 	case PT_LOAD:
824 	    if (nsegs == 0) {	/* First load segment */
825 		obj->vaddrbase = trunc_page(ph->p_vaddr);
826 		obj->mapbase = (caddr_t) obj->vaddrbase;
827 		obj->relocbase = obj->mapbase - obj->vaddrbase;
828 		obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
829 		  obj->vaddrbase;
830 	    } else {		/* Last load segment */
831 		obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
832 		  obj->vaddrbase;
833 	    }
834 	    nsegs++;
835 	    break;
836 
837 	case PT_DYNAMIC:
838 	    obj->dynamic = (const Elf_Dyn *) ph->p_vaddr;
839 	    break;
840 
841 	case PT_TLS:
842 	    obj->tlsindex = 1;
843 	    obj->tlssize = ph->p_memsz;
844 	    obj->tlsalign = ph->p_align;
845 	    obj->tlsinitsize = ph->p_filesz;
846 	    obj->tlsinit = (void*) ph->p_vaddr;
847 	    break;
848 	}
849     }
850     if (nsegs < 1) {
851 	_rtld_error("%s: too few PT_LOAD segments", path);
852 	return NULL;
853     }
854 
855     obj->entry = entry;
856     return obj;
857 }
858 
859 static Obj_Entry *
860 dlcheck(void *handle)
861 {
862     Obj_Entry *obj;
863 
864     for (obj = obj_list;  obj != NULL;  obj = obj->next)
865 	if (obj == (Obj_Entry *) handle)
866 	    break;
867 
868     if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
869 	_rtld_error("Invalid shared object handle %p", handle);
870 	return NULL;
871     }
872     return obj;
873 }
874 
875 /*
876  * If the given object is already in the donelist, return true.  Otherwise
877  * add the object to the list and return false.
878  */
879 static bool
880 donelist_check(DoneList *dlp, const Obj_Entry *obj)
881 {
882     unsigned int i;
883 
884     for (i = 0;  i < dlp->num_used;  i++)
885 	if (dlp->objs[i] == obj)
886 	    return true;
887     /*
888      * Our donelist allocation should always be sufficient.  But if
889      * our threads locking isn't working properly, more shared objects
890      * could have been loaded since we allocated the list.  That should
891      * never happen, but we'll handle it properly just in case it does.
892      */
893     if (dlp->num_used < dlp->num_alloc)
894 	dlp->objs[dlp->num_used++] = obj;
895     return false;
896 }
897 
898 /*
899  * Hash function for symbol table lookup.  Don't even think about changing
900  * this.  It is specified by the System V ABI.
901  */
902 unsigned long
903 elf_hash(const char *name)
904 {
905     const unsigned char *p = (const unsigned char *) name;
906     unsigned long h = 0;
907     unsigned long g;
908 
909     while (*p != '\0') {
910 	h = (h << 4) + *p++;
911 	if ((g = h & 0xf0000000) != 0)
912 	    h ^= g >> 24;
913 	h &= ~g;
914     }
915     return h;
916 }
917 
918 /*
919  * Find the library with the given name, and return its full pathname.
920  * The returned string is dynamically allocated.  Generates an error
921  * message and returns NULL if the library cannot be found.
922  *
923  * If the second argument is non-NULL, then it refers to an already-
924  * loaded shared object, whose library search path will be searched.
925  *
926  * The search order is:
927  *   LD_LIBRARY_PATH
928  *   rpath in the referencing file
929  *   ldconfig hints
930  *   /usr/lib
931  */
932 static char *
933 find_library(const char *name, const Obj_Entry *refobj)
934 {
935     char *pathname;
936 
937     if (strchr(name, '/') != NULL) {	/* Hard coded pathname */
938 	if (name[0] != '/' && !trust) {
939 	    _rtld_error("Absolute pathname required for shared object \"%s\"",
940 	      name);
941 	    return NULL;
942 	}
943 	return xstrdup(name);
944     }
945 
946     dbg(" Searching for \"%s\"", name);
947 
948     if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
949       (refobj != NULL &&
950       (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
951       (pathname = search_library_path(name, gethints())) != NULL ||
952       (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
953 	return pathname;
954 
955     if(refobj != NULL && refobj->path != NULL) {
956 	_rtld_error("Shared object \"%s\" not found, required by \"%s\"",
957 	  name, basename(refobj->path));
958     } else {
959 	_rtld_error("Shared object \"%s\" not found", name);
960     }
961     return NULL;
962 }
963 
964 /*
965  * Given a symbol number in a referencing object, find the corresponding
966  * definition of the symbol.  Returns a pointer to the symbol, or NULL if
967  * no definition was found.  Returns a pointer to the Obj_Entry of the
968  * defining object via the reference parameter DEFOBJ_OUT.
969  */
970 const Elf_Sym *
971 find_symdef(unsigned long symnum, const Obj_Entry *refobj,
972     const Obj_Entry **defobj_out, bool in_plt, SymCache *cache)
973 {
974     const Elf_Sym *ref;
975     const Elf_Sym *def;
976     const Obj_Entry *defobj;
977     const char *name;
978     unsigned long hash;
979 
980     /*
981      * If we have already found this symbol, get the information from
982      * the cache.
983      */
984     if (symnum >= refobj->nchains)
985 	return NULL;	/* Bad object */
986     if (cache != NULL && cache[symnum].sym != NULL) {
987 	*defobj_out = cache[symnum].obj;
988 	return cache[symnum].sym;
989     }
990 
991     ref = refobj->symtab + symnum;
992     name = refobj->strtab + ref->st_name;
993     hash = elf_hash(name);
994     defobj = NULL;
995 
996     def = symlook_default(name, hash, refobj, &defobj, in_plt);
997 
998     /*
999      * If we found no definition and the reference is weak, treat the
1000      * symbol as having the value zero.
1001      */
1002     if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
1003 	def = &sym_zero;
1004 	defobj = obj_main;
1005     }
1006 
1007     if (def != NULL) {
1008 	*defobj_out = defobj;
1009 	/* Record the information in the cache to avoid subsequent lookups. */
1010 	if (cache != NULL) {
1011 	    cache[symnum].sym = def;
1012 	    cache[symnum].obj = defobj;
1013 	}
1014     } else
1015 	_rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
1016     return def;
1017 }
1018 
1019 /*
1020  * Return the search path from the ldconfig hints file, reading it if
1021  * necessary.  Returns NULL if there are problems with the hints file,
1022  * or if the search path there is empty.
1023  */
1024 static const char *
1025 gethints(void)
1026 {
1027     static char *hints;
1028 
1029     if (hints == NULL) {
1030 	int fd;
1031 	struct elfhints_hdr hdr;
1032 	char *p;
1033 
1034 	/* Keep from trying again in case the hints file is bad. */
1035 	hints = "";
1036 
1037 	if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1)
1038 	    return NULL;
1039 	if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
1040 	  hdr.magic != ELFHINTS_MAGIC ||
1041 	  hdr.version != 1) {
1042 	    close(fd);
1043 	    return NULL;
1044 	}
1045 	p = xmalloc(hdr.dirlistlen + 1);
1046 	if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
1047 	  read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) {
1048 	    free(p);
1049 	    close(fd);
1050 	    return NULL;
1051 	}
1052 	hints = p;
1053 	close(fd);
1054     }
1055     return hints[0] != '\0' ? hints : NULL;
1056 }
1057 
1058 static void
1059 init_dag(Obj_Entry *root)
1060 {
1061     DoneList donelist;
1062 
1063     donelist_init(&donelist);
1064     init_dag1(root, root, &donelist);
1065 }
1066 
1067 static void
1068 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp)
1069 {
1070     const Needed_Entry *needed;
1071 
1072     if (donelist_check(dlp, obj))
1073 	return;
1074     objlist_push_tail(&obj->dldags, root);
1075     objlist_push_tail(&root->dagmembers, obj);
1076     for (needed = obj->needed;  needed != NULL;  needed = needed->next)
1077 	if (needed->obj != NULL)
1078 	    init_dag1(root, needed->obj, dlp);
1079 }
1080 
1081 /*
1082  * Initialize the dynamic linker.  The argument is the address at which
1083  * the dynamic linker has been mapped into memory.  The primary task of
1084  * this function is to relocate the dynamic linker.
1085  */
1086 static void
1087 init_rtld(caddr_t mapbase)
1088 {
1089     /*
1090      * Conjure up an Obj_Entry structure for the dynamic linker.
1091      *
1092      * The "path" member is supposed to be dynamically-allocated, but we
1093      * aren't yet initialized sufficiently to do that.  Below we will
1094      * replace the static version with a dynamically-allocated copy.
1095      */
1096     obj_rtld.path = PATH_RTLD;
1097     obj_rtld.rtld = true;
1098     obj_rtld.mapbase = mapbase;
1099 #ifdef PIC
1100     obj_rtld.relocbase = mapbase;
1101 #endif
1102     if (&_DYNAMIC != 0) {
1103 	obj_rtld.dynamic = rtld_dynamic(&obj_rtld);
1104 	digest_dynamic(&obj_rtld);
1105 	assert(obj_rtld.needed == NULL);
1106 	assert(!obj_rtld.textrel);
1107 
1108 	/*
1109 	 * Temporarily put the dynamic linker entry into the object list, so
1110 	 * that symbols can be found.
1111 	 */
1112 	obj_list = &obj_rtld;
1113 	obj_tail = &obj_rtld.next;
1114 	obj_count = 1;
1115 
1116 	relocate_objects(&obj_rtld, true);
1117     }
1118 
1119     /* Make the object list empty again. */
1120     obj_list = NULL;
1121     obj_tail = &obj_list;
1122     obj_count = 0;
1123 
1124     /* Replace the path with a dynamically allocated copy. */
1125     obj_rtld.path = xstrdup(obj_rtld.path);
1126 
1127     r_debug.r_brk = r_debug_state;
1128     r_debug.r_state = RT_CONSISTENT;
1129 }
1130 
1131 /*
1132  * Add the init functions from a needed object list (and its recursive
1133  * needed objects) to "list".  This is not used directly; it is a helper
1134  * function for initlist_add_objects().  The write lock must be held
1135  * when this function is called.
1136  */
1137 static void
1138 initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1139 {
1140     /* Recursively process the successor needed objects. */
1141     if (needed->next != NULL)
1142 	initlist_add_neededs(needed->next, list);
1143 
1144     /* Process the current needed object. */
1145     if (needed->obj != NULL)
1146 	initlist_add_objects(needed->obj, &needed->obj->next, list);
1147 }
1148 
1149 /*
1150  * Scan all of the DAGs rooted in the range of objects from "obj" to
1151  * "tail" and add their init functions to "list".  This recurses over
1152  * the DAGs and ensure the proper init ordering such that each object's
1153  * needed libraries are initialized before the object itself.  At the
1154  * same time, this function adds the objects to the global finalization
1155  * list "list_fini" in the opposite order.  The write lock must be
1156  * held when this function is called.
1157  */
1158 static void
1159 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1160 {
1161     if (obj->init_done)
1162 	return;
1163     obj->init_done = true;
1164 
1165     /* Recursively process the successor objects. */
1166     if (&obj->next != tail)
1167 	initlist_add_objects(obj->next, tail, list);
1168 
1169     /* Recursively process the needed objects. */
1170     if (obj->needed != NULL)
1171 	initlist_add_neededs(obj->needed, list);
1172 
1173     /* Add the object to the init list. */
1174     if (obj->init != NULL)
1175 	objlist_push_tail(list, obj);
1176 
1177     /* Add the object to the global fini list in the reverse order. */
1178     if (obj->fini != NULL)
1179 	objlist_push_head(&list_fini, obj);
1180 }
1181 
1182 static bool
1183 is_exported(const Elf_Sym *def)
1184 {
1185     func_ptr_type value;
1186     const func_ptr_type *p;
1187 
1188     value = (func_ptr_type)(obj_rtld.relocbase + def->st_value);
1189     for (p = exports;  *p != NULL;  p++)
1190 	if (*p == value)
1191 	    return true;
1192     return false;
1193 }
1194 
1195 /*
1196  * Given a shared object, traverse its list of needed objects, and load
1197  * each of them.  Returns 0 on success.  Generates an error message and
1198  * returns -1 on failure.
1199  */
1200 static int
1201 load_needed_objects(Obj_Entry *first)
1202 {
1203     Obj_Entry *obj;
1204 
1205     for (obj = first;  obj != NULL;  obj = obj->next) {
1206 	Needed_Entry *needed;
1207 
1208 	for (needed = obj->needed;  needed != NULL;  needed = needed->next) {
1209 	    const char *name = obj->strtab + needed->name;
1210 	    char *path = find_library(name, obj);
1211 
1212 	    needed->obj = NULL;
1213 	    if (path == NULL && !ld_tracing)
1214 		return -1;
1215 
1216 	    if (path) {
1217 		needed->obj = load_object(path);
1218 		if (needed->obj == NULL && !ld_tracing)
1219 		    return -1;		/* XXX - cleanup */
1220 	    }
1221 	}
1222     }
1223 
1224     return 0;
1225 }
1226 
1227 static int
1228 load_preload_objects(void)
1229 {
1230     char *p = ld_preload;
1231     static const char delim[] = " \t:;";
1232 
1233     if (p == NULL)
1234 	return NULL;
1235 
1236     p += strspn(p, delim);
1237     while (*p != '\0') {
1238 	size_t len = strcspn(p, delim);
1239 	char *path;
1240 	char savech;
1241 
1242 	savech = p[len];
1243 	p[len] = '\0';
1244 	if ((path = find_library(p, NULL)) == NULL)
1245 	    return -1;
1246 	if (load_object(path) == NULL)
1247 	    return -1;	/* XXX - cleanup */
1248 	p[len] = savech;
1249 	p += len;
1250 	p += strspn(p, delim);
1251     }
1252     return 0;
1253 }
1254 
1255 /*
1256  * Returns a pointer to the Obj_Entry for the object with the given path.
1257  * Returns NULL if no matching object was found.
1258  */
1259 static Obj_Entry *
1260 find_object(const char *path)
1261 {
1262     Obj_Entry *obj;
1263 
1264     for (obj = obj_list->next;  obj != NULL;  obj = obj->next) {
1265 	if (strcmp(obj->path, path) == 0)
1266 	    return(obj);
1267     }
1268     return(NULL);
1269 }
1270 
1271 /*
1272  * Returns a pointer to the Obj_Entry for the object matching device and
1273  * inode of the given path. If no matching object was found, the descriptor
1274  * is returned in fd.
1275  * Returns with obj == NULL && fd == -1 on error.
1276  */
1277 static Obj_Entry *
1278 find_object2(const char *path, int *fd, struct stat *sb)
1279 {
1280     Obj_Entry *obj;
1281 
1282     if ((*fd = open(path, O_RDONLY)) == -1) {
1283 	_rtld_error("Cannot open \"%s\"", path);
1284 	return(NULL);
1285     }
1286 
1287     if (fstat(*fd, sb) == -1) {
1288 	_rtld_error("Cannot fstat \"%s\"", path);
1289 	close(*fd);
1290 	*fd = -1;
1291 	return NULL;
1292     }
1293 
1294     for (obj = obj_list->next;  obj != NULL;  obj = obj->next) {
1295 	if (obj->ino == sb->st_ino && obj->dev == sb->st_dev) {
1296 	    close(*fd);
1297 	    break;
1298 	}
1299     }
1300 
1301     return(obj);
1302 }
1303 
1304 /*
1305  * Load a shared object into memory, if it is not already loaded.  The
1306  * argument must be a string allocated on the heap.  This function assumes
1307  * responsibility for freeing it when necessary.
1308  *
1309  * Returns a pointer to the Obj_Entry for the object.  Returns NULL
1310  * on failure.
1311  */
1312 static Obj_Entry *
1313 load_object(char *path)
1314 {
1315     Obj_Entry *obj;
1316     int fd = -1;
1317     struct stat sb;
1318 
1319     obj = find_object(path);
1320     if (obj != NULL) {
1321 	obj->refcount++;
1322 	free(path);
1323 	return(obj);
1324     }
1325 
1326     obj = find_object2(path, &fd, &sb);
1327     if (obj != NULL) {
1328 	obj->refcount++;
1329 	free(path);
1330 	return(obj);
1331     } else if (fd == -1) {
1332 	free(path);
1333 	return(NULL);
1334     }
1335 
1336     dbg("loading \"%s\"", path);
1337     obj = map_object(fd, path, &sb);
1338     close(fd);
1339     if (obj == NULL) {
1340 	free(path);
1341         return NULL;
1342     }
1343 
1344     obj->path = path;
1345     digest_dynamic(obj);
1346 
1347     *obj_tail = obj;
1348     obj_tail = &obj->next;
1349     obj_count++;
1350     linkmap_add(obj);	/* for GDB & dlinfo() */
1351 
1352     dbg("  %p .. %p: %s", obj->mapbase, obj->mapbase + obj->mapsize - 1,
1353 	obj->path);
1354     if (obj->textrel)
1355         dbg("  WARNING: %s has impure text", obj->path);
1356 
1357     obj->refcount++;
1358     return obj;
1359 }
1360 
1361 /*
1362  * Check for locking violations and die if one is found.
1363  */
1364 static void
1365 lock_check(void)
1366 {
1367     int rcount, wcount;
1368 
1369     rcount = lockinfo.rcount;
1370     wcount = lockinfo.wcount;
1371     assert(rcount >= 0);
1372     assert(wcount >= 0);
1373     if (wcount > 1 || (wcount != 0 && rcount != 0)) {
1374 	_rtld_error("Application locking error: %d readers and %d writers"
1375 	  " in dynamic linker.  See DLLOCKINIT(3) in manual pages.",
1376 	  rcount, wcount);
1377 	die();
1378     }
1379 }
1380 
1381 static Obj_Entry *
1382 obj_from_addr(const void *addr)
1383 {
1384     Obj_Entry *obj;
1385 
1386     for (obj = obj_list;  obj != NULL;  obj = obj->next) {
1387 	if (addr < (void *) obj->mapbase)
1388 	    continue;
1389 	if (addr < (void *) (obj->mapbase + obj->mapsize))
1390 	    return obj;
1391     }
1392     return NULL;
1393 }
1394 
1395 /*
1396  * Call the finalization functions for each of the objects in "list"
1397  * which are unreferenced.  All of the objects are expected to have
1398  * non-NULL fini functions.
1399  */
1400 static void
1401 objlist_call_fini(Objlist *list)
1402 {
1403     Objlist_Entry *elm;
1404     char *saved_msg;
1405 
1406     /*
1407      * Preserve the current error message since a fini function might
1408      * call into the dynamic linker and overwrite it.
1409      */
1410     saved_msg = errmsg_save();
1411     STAILQ_FOREACH(elm, list, link) {
1412 	if (elm->obj->refcount == 0) {
1413 	    dbg("calling fini function for %s", elm->obj->path);
1414 	    (*elm->obj->fini)();
1415 	}
1416     }
1417     errmsg_restore(saved_msg);
1418 }
1419 
1420 /*
1421  * Call the initialization functions for each of the objects in
1422  * "list".  All of the objects are expected to have non-NULL init
1423  * functions.
1424  */
1425 static void
1426 objlist_call_init(Objlist *list)
1427 {
1428     Objlist_Entry *elm;
1429     char *saved_msg;
1430 
1431     /*
1432      * Preserve the current error message since an init function might
1433      * call into the dynamic linker and overwrite it.
1434      */
1435     saved_msg = errmsg_save();
1436     STAILQ_FOREACH(elm, list, link) {
1437 	dbg("calling init function for %s", elm->obj->path);
1438 	(*elm->obj->init)();
1439     }
1440     errmsg_restore(saved_msg);
1441 }
1442 
1443 static void
1444 objlist_clear(Objlist *list)
1445 {
1446     Objlist_Entry *elm;
1447 
1448     while (!STAILQ_EMPTY(list)) {
1449 	elm = STAILQ_FIRST(list);
1450 	STAILQ_REMOVE_HEAD(list, link);
1451 	free(elm);
1452     }
1453 }
1454 
1455 static Objlist_Entry *
1456 objlist_find(Objlist *list, const Obj_Entry *obj)
1457 {
1458     Objlist_Entry *elm;
1459 
1460     STAILQ_FOREACH(elm, list, link)
1461 	if (elm->obj == obj)
1462 	    return elm;
1463     return NULL;
1464 }
1465 
1466 static void
1467 objlist_init(Objlist *list)
1468 {
1469     STAILQ_INIT(list);
1470 }
1471 
1472 static void
1473 objlist_push_head(Objlist *list, Obj_Entry *obj)
1474 {
1475     Objlist_Entry *elm;
1476 
1477     elm = NEW(Objlist_Entry);
1478     elm->obj = obj;
1479     STAILQ_INSERT_HEAD(list, elm, link);
1480 }
1481 
1482 static void
1483 objlist_push_tail(Objlist *list, Obj_Entry *obj)
1484 {
1485     Objlist_Entry *elm;
1486 
1487     elm = NEW(Objlist_Entry);
1488     elm->obj = obj;
1489     STAILQ_INSERT_TAIL(list, elm, link);
1490 }
1491 
1492 static void
1493 objlist_remove(Objlist *list, Obj_Entry *obj)
1494 {
1495     Objlist_Entry *elm;
1496 
1497     if ((elm = objlist_find(list, obj)) != NULL) {
1498 	STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
1499 	free(elm);
1500     }
1501 }
1502 
1503 /*
1504  * Remove all of the unreferenced objects from "list".
1505  */
1506 static void
1507 objlist_remove_unref(Objlist *list)
1508 {
1509     Objlist newlist;
1510     Objlist_Entry *elm;
1511 
1512     STAILQ_INIT(&newlist);
1513     while (!STAILQ_EMPTY(list)) {
1514 	elm = STAILQ_FIRST(list);
1515 	STAILQ_REMOVE_HEAD(list, link);
1516 	if (elm->obj->refcount == 0)
1517 	    free(elm);
1518 	else
1519 	    STAILQ_INSERT_TAIL(&newlist, elm, link);
1520     }
1521     *list = newlist;
1522 }
1523 
1524 /*
1525  * Relocate newly-loaded shared objects.  The argument is a pointer to
1526  * the Obj_Entry for the first such object.  All objects from the first
1527  * to the end of the list of objects are relocated.  Returns 0 on success,
1528  * or -1 on failure.
1529  */
1530 static int
1531 relocate_objects(Obj_Entry *first, bool bind_now)
1532 {
1533     Obj_Entry *obj;
1534 
1535     for (obj = first;  obj != NULL;  obj = obj->next) {
1536 	if (obj != &obj_rtld)
1537 	    dbg("relocating \"%s\"", obj->path);
1538 	if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL ||
1539 	    obj->symtab == NULL || obj->strtab == NULL) {
1540 	    _rtld_error("%s: Shared object has no run-time symbol table",
1541 	      obj->path);
1542 	    return -1;
1543 	}
1544 
1545 	if (obj->textrel) {
1546 	    /* There are relocations to the write-protected text segment. */
1547 	    if (mprotect(obj->mapbase, obj->textsize,
1548 	      PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
1549 		_rtld_error("%s: Cannot write-enable text segment: %s",
1550 		  obj->path, strerror(errno));
1551 		return -1;
1552 	    }
1553 	}
1554 
1555 	/* Process the non-PLT relocations. */
1556 	if (reloc_non_plt(obj, &obj_rtld))
1557 		return -1;
1558 
1559 	/*
1560 	 * Reprotect the text segment.  Make sure it is included in the
1561 	 * core dump since we modified it.  This unfortunately causes the
1562 	 * entire text segment to core-out but we don't have much of a
1563 	 * choice.  We could try to only reenable core dumps on pages
1564 	 * in which relocations occured but that is likely most of the text
1565 	 * pages anyway, and even that would not work because the rest of
1566 	 * the text pages would wind up as a read-only OBJT_DEFAULT object
1567 	 * (created due to our modifications) backed by the original OBJT_VNODE
1568 	 * object, and the ELF coredump code is currently only able to dump
1569 	 * vnode records for pure vnode-backed mappings, not vnode backings
1570 	 * to memory objects.
1571 	 */
1572 	if (obj->textrel) {
1573 	    madvise(obj->mapbase, obj->textsize, MADV_CORE);
1574 	    if (mprotect(obj->mapbase, obj->textsize,
1575 	      PROT_READ|PROT_EXEC) == -1) {
1576 		_rtld_error("%s: Cannot write-protect text segment: %s",
1577 		  obj->path, strerror(errno));
1578 		return -1;
1579 	    }
1580 	}
1581 
1582 	/* Process the PLT relocations. */
1583 	if (reloc_plt(obj) == -1)
1584 	    return -1;
1585 	/* Relocate the jump slots if we are doing immediate binding. */
1586 	if (obj->bind_now || bind_now)
1587 	    if (reloc_jmpslots(obj) == -1)
1588 		return -1;
1589 
1590 
1591 	/*
1592 	 * Set up the magic number and version in the Obj_Entry.  These
1593 	 * were checked in the crt1.o from the original ElfKit, so we
1594 	 * set them for backward compatibility.
1595 	 */
1596 	obj->magic = RTLD_MAGIC;
1597 	obj->version = RTLD_VERSION;
1598 
1599 	/* Set the special PLT or GOT entries. */
1600 	init_pltgot(obj);
1601     }
1602 
1603     return 0;
1604 }
1605 
1606 /*
1607  * Cleanup procedure.  It will be called (by the atexit mechanism) just
1608  * before the process exits.
1609  */
1610 static void
1611 rtld_exit(void)
1612 {
1613     Obj_Entry *obj;
1614 
1615     dbg("rtld_exit()");
1616     /* Clear all the reference counts so the fini functions will be called. */
1617     for (obj = obj_list;  obj != NULL;  obj = obj->next)
1618 	obj->refcount = 0;
1619     objlist_call_fini(&list_fini);
1620     /* No need to remove the items from the list, since we are exiting. */
1621 }
1622 
1623 static void *
1624 path_enumerate(const char *path, path_enum_proc callback, void *arg)
1625 {
1626     if (path == NULL)
1627 	return (NULL);
1628 
1629     path += strspn(path, ":;");
1630     while (*path != '\0') {
1631 	size_t len;
1632 	char  *res;
1633 
1634 	len = strcspn(path, ":;");
1635 	res = callback(path, len, arg);
1636 
1637 	if (res != NULL)
1638 	    return (res);
1639 
1640 	path += len;
1641 	path += strspn(path, ":;");
1642     }
1643 
1644     return (NULL);
1645 }
1646 
1647 struct try_library_args {
1648     const char	*name;
1649     size_t	 namelen;
1650     char	*buffer;
1651     size_t	 buflen;
1652 };
1653 
1654 static void *
1655 try_library_path(const char *dir, size_t dirlen, void *param)
1656 {
1657     struct try_library_args *arg;
1658 
1659     arg = param;
1660     if (*dir == '/' || trust) {
1661 	char *pathname;
1662 
1663 	if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
1664 		return (NULL);
1665 
1666 	pathname = arg->buffer;
1667 	strncpy(pathname, dir, dirlen);
1668 	pathname[dirlen] = '/';
1669 	strcpy(pathname + dirlen + 1, arg->name);
1670 
1671 	dbg("  Trying \"%s\"", pathname);
1672 	if (access(pathname, F_OK) == 0) {		/* We found it */
1673 	    pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
1674 	    strcpy(pathname, arg->buffer);
1675 	    return (pathname);
1676 	}
1677     }
1678     return (NULL);
1679 }
1680 
1681 static char *
1682 search_library_path(const char *name, const char *path)
1683 {
1684     char *p;
1685     struct try_library_args arg;
1686 
1687     if (path == NULL)
1688 	return NULL;
1689 
1690     arg.name = name;
1691     arg.namelen = strlen(name);
1692     arg.buffer = xmalloc(PATH_MAX);
1693     arg.buflen = PATH_MAX;
1694 
1695     p = path_enumerate(path, try_library_path, &arg);
1696 
1697     free(arg.buffer);
1698 
1699     return (p);
1700 }
1701 
1702 int
1703 dlclose(void *handle)
1704 {
1705     Obj_Entry *root;
1706 
1707     wlock_acquire();
1708     root = dlcheck(handle);
1709     if (root == NULL) {
1710 	wlock_release();
1711 	return -1;
1712     }
1713 
1714     /* Unreference the object and its dependencies. */
1715     root->dl_refcount--;
1716     unref_dag(root);
1717 
1718     if (root->refcount == 0) {
1719 	/*
1720 	 * The object is no longer referenced, so we must unload it.
1721 	 * First, call the fini functions with no locks held.
1722 	 */
1723 	wlock_release();
1724 	objlist_call_fini(&list_fini);
1725 	wlock_acquire();
1726 	objlist_remove_unref(&list_fini);
1727 
1728 	/* Finish cleaning up the newly-unreferenced objects. */
1729 	GDB_STATE(RT_DELETE,&root->linkmap);
1730 	unload_object(root);
1731 	GDB_STATE(RT_CONSISTENT,NULL);
1732     }
1733     wlock_release();
1734     return 0;
1735 }
1736 
1737 const char *
1738 dlerror(void)
1739 {
1740     char *msg = error_message;
1741     error_message = NULL;
1742     return msg;
1743 }
1744 
1745 void *
1746 dlopen(const char *name, int mode)
1747 {
1748     Obj_Entry **old_obj_tail;
1749     Obj_Entry *obj;
1750     Objlist initlist;
1751     int result;
1752 
1753     ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
1754     if (ld_tracing != NULL)
1755 	environ = (char **)*get_program_var_addr("environ");
1756 
1757     objlist_init(&initlist);
1758 
1759     wlock_acquire();
1760     GDB_STATE(RT_ADD,NULL);
1761 
1762     old_obj_tail = obj_tail;
1763     obj = NULL;
1764     if (name == NULL) {
1765 	obj = obj_main;
1766 	obj->refcount++;
1767     } else {
1768 	char *path = find_library(name, obj_main);
1769 	if (path != NULL)
1770 	    obj = load_object(path);
1771     }
1772 
1773     if (obj) {
1774 	obj->dl_refcount++;
1775 	if ((mode & RTLD_GLOBAL) && objlist_find(&list_global, obj) == NULL)
1776 	    objlist_push_tail(&list_global, obj);
1777 	mode &= RTLD_MODEMASK;
1778 	if (*old_obj_tail != NULL) {		/* We loaded something new. */
1779 	    assert(*old_obj_tail == obj);
1780 
1781 	    result = load_needed_objects(obj);
1782 	    if (result != -1 && ld_tracing)
1783 		goto trace;
1784 
1785 	    if (result == -1 ||
1786 	      (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW)) == -1) {
1787 		obj->dl_refcount--;
1788 		unref_dag(obj);
1789 		if (obj->refcount == 0)
1790 		    unload_object(obj);
1791 		obj = NULL;
1792 	    } else {
1793 		/* Make list of init functions to call. */
1794 		initlist_add_objects(obj, &obj->next, &initlist);
1795 	    }
1796 	} else if (ld_tracing)
1797 	    goto trace;
1798     }
1799 
1800     GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
1801 
1802     /* Call the init functions with no locks held. */
1803     wlock_release();
1804     objlist_call_init(&initlist);
1805     wlock_acquire();
1806     objlist_clear(&initlist);
1807     wlock_release();
1808     return obj;
1809 trace:
1810     trace_loaded_objects(obj);
1811     wlock_release();
1812     exit(0);
1813 }
1814 
1815 void *
1816 dlsym(void *handle, const char *name)
1817 {
1818     const Obj_Entry *obj;
1819     unsigned long hash;
1820     const Elf_Sym *def;
1821     const Obj_Entry *defobj;
1822 
1823     hash = elf_hash(name);
1824     def = NULL;
1825     defobj = NULL;
1826 
1827     rlock_acquire();
1828     if (handle == NULL || handle == RTLD_NEXT ||
1829 	handle == RTLD_DEFAULT || handle == RTLD_SELF) {
1830 	void *retaddr;
1831 
1832 	retaddr = __builtin_return_address(0);	/* __GNUC__ only */
1833 	if ((obj = obj_from_addr(retaddr)) == NULL) {
1834 	    _rtld_error("Cannot determine caller's shared object");
1835 	    rlock_release();
1836 	    return NULL;
1837 	}
1838 	if (handle == NULL) {	/* Just the caller's shared object. */
1839 	    def = symlook_obj(name, hash, obj, true);
1840 	    defobj = obj;
1841 	} else if (handle == RTLD_NEXT || /* Objects after caller's */
1842 		   handle == RTLD_SELF) { /* ... caller included */
1843 	    if (handle == RTLD_NEXT)
1844 		obj = obj->next;
1845 	    for (; obj != NULL; obj = obj->next) {
1846 		if ((def = symlook_obj(name, hash, obj, true)) != NULL) {
1847 		    defobj = obj;
1848 		    break;
1849 		}
1850 	    }
1851 	} else {
1852 	    assert(handle == RTLD_DEFAULT);
1853 	    def = symlook_default(name, hash, obj, &defobj, true);
1854 	}
1855     } else {
1856 	if ((obj = dlcheck(handle)) == NULL) {
1857 	    rlock_release();
1858 	    return NULL;
1859 	}
1860 
1861 	if (obj->mainprog) {
1862 	    DoneList donelist;
1863 
1864 	    /* Search main program and all libraries loaded by it. */
1865 	    donelist_init(&donelist);
1866 	    def = symlook_list(name, hash, &list_main, &defobj, true,
1867 	      &donelist);
1868 	} else {
1869 	    /*
1870 	     * XXX - This isn't correct.  The search should include the whole
1871 	     * DAG rooted at the given object.
1872 	     */
1873 	    def = symlook_obj(name, hash, obj, true);
1874 	    defobj = obj;
1875 	}
1876     }
1877 
1878     if (def != NULL) {
1879 	rlock_release();
1880 	return defobj->relocbase + def->st_value;
1881     }
1882 
1883     _rtld_error("Undefined symbol \"%s\"", name);
1884     rlock_release();
1885     return NULL;
1886 }
1887 
1888 int
1889 dladdr(const void *addr, Dl_info *info)
1890 {
1891     const Obj_Entry *obj;
1892     const Elf_Sym *def;
1893     void *symbol_addr;
1894     unsigned long symoffset;
1895 
1896     rlock_acquire();
1897     obj = obj_from_addr(addr);
1898     if (obj == NULL) {
1899         _rtld_error("No shared object contains address");
1900 	rlock_release();
1901         return 0;
1902     }
1903     info->dli_fname = obj->path;
1904     info->dli_fbase = obj->mapbase;
1905     info->dli_saddr = (void *)0;
1906     info->dli_sname = NULL;
1907 
1908     /*
1909      * Walk the symbol list looking for the symbol whose address is
1910      * closest to the address sent in.
1911      */
1912     for (symoffset = 0; symoffset < obj->nchains; symoffset++) {
1913         def = obj->symtab + symoffset;
1914 
1915         /*
1916          * For skip the symbol if st_shndx is either SHN_UNDEF or
1917          * SHN_COMMON.
1918          */
1919         if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
1920             continue;
1921 
1922         /*
1923          * If the symbol is greater than the specified address, or if it
1924          * is further away from addr than the current nearest symbol,
1925          * then reject it.
1926          */
1927         symbol_addr = obj->relocbase + def->st_value;
1928         if (symbol_addr > addr || symbol_addr < info->dli_saddr)
1929             continue;
1930 
1931         /* Update our idea of the nearest symbol. */
1932         info->dli_sname = obj->strtab + def->st_name;
1933         info->dli_saddr = symbol_addr;
1934 
1935         /* Exact match? */
1936         if (info->dli_saddr == addr)
1937             break;
1938     }
1939     rlock_release();
1940     return 1;
1941 }
1942 
1943 int
1944 dlinfo(void *handle, int request, void *p)
1945 {
1946     const Obj_Entry *obj;
1947     int error;
1948 
1949     rlock_acquire();
1950 
1951     if (handle == NULL || handle == RTLD_SELF) {
1952 	void *retaddr;
1953 
1954 	retaddr = __builtin_return_address(0);	/* __GNUC__ only */
1955 	if ((obj = obj_from_addr(retaddr)) == NULL)
1956 	    _rtld_error("Cannot determine caller's shared object");
1957     } else
1958 	obj = dlcheck(handle);
1959 
1960     if (obj == NULL) {
1961 	rlock_release();
1962 	return (-1);
1963     }
1964 
1965     error = 0;
1966     switch (request) {
1967     case RTLD_DI_LINKMAP:
1968 	*((struct link_map const **)p) = &obj->linkmap;
1969 	break;
1970     case RTLD_DI_ORIGIN:
1971 	error = rtld_dirname(obj->path, p);
1972 	break;
1973 
1974     case RTLD_DI_SERINFOSIZE:
1975     case RTLD_DI_SERINFO:
1976 	error = do_search_info(obj, request, (struct dl_serinfo *)p);
1977 	break;
1978 
1979     default:
1980 	_rtld_error("Invalid request %d passed to dlinfo()", request);
1981 	error = -1;
1982     }
1983 
1984     rlock_release();
1985 
1986     return (error);
1987 }
1988 
1989 struct fill_search_info_args {
1990     int		 request;
1991     unsigned int flags;
1992     Dl_serinfo  *serinfo;
1993     Dl_serpath  *serpath;
1994     char	*strspace;
1995 };
1996 
1997 static void *
1998 fill_search_info(const char *dir, size_t dirlen, void *param)
1999 {
2000     struct fill_search_info_args *arg;
2001 
2002     arg = param;
2003 
2004     if (arg->request == RTLD_DI_SERINFOSIZE) {
2005 	arg->serinfo->dls_cnt ++;
2006 	arg->serinfo->dls_size += dirlen + 1;
2007     } else {
2008 	struct dl_serpath *s_entry;
2009 
2010 	s_entry = arg->serpath;
2011 	s_entry->dls_name  = arg->strspace;
2012 	s_entry->dls_flags = arg->flags;
2013 
2014 	strncpy(arg->strspace, dir, dirlen);
2015 	arg->strspace[dirlen] = '\0';
2016 
2017 	arg->strspace += dirlen + 1;
2018 	arg->serpath++;
2019     }
2020 
2021     return (NULL);
2022 }
2023 
2024 static int
2025 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
2026 {
2027     struct dl_serinfo _info;
2028     struct fill_search_info_args args;
2029 
2030     args.request = RTLD_DI_SERINFOSIZE;
2031     args.serinfo = &_info;
2032 
2033     _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
2034     _info.dls_cnt  = 0;
2035 
2036     path_enumerate(ld_library_path, fill_search_info, &args);
2037     path_enumerate(obj->rpath, fill_search_info, &args);
2038     path_enumerate(gethints(), fill_search_info, &args);
2039     path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
2040 
2041 
2042     if (request == RTLD_DI_SERINFOSIZE) {
2043 	info->dls_size = _info.dls_size;
2044 	info->dls_cnt = _info.dls_cnt;
2045 	return (0);
2046     }
2047 
2048     if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
2049 	_rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
2050 	return (-1);
2051     }
2052 
2053     args.request  = RTLD_DI_SERINFO;
2054     args.serinfo  = info;
2055     args.serpath  = &info->dls_serpath[0];
2056     args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
2057 
2058     args.flags = LA_SER_LIBPATH;
2059     if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
2060 	return (-1);
2061 
2062     args.flags = LA_SER_RUNPATH;
2063     if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
2064 	return (-1);
2065 
2066     args.flags = LA_SER_CONFIG;
2067     if (path_enumerate(gethints(), fill_search_info, &args) != NULL)
2068 	return (-1);
2069 
2070     args.flags = LA_SER_DEFAULT;
2071     if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
2072 	return (-1);
2073     return (0);
2074 }
2075 
2076 static int
2077 rtld_dirname(const char *path, char *bname)
2078 {
2079     const char *endp;
2080 
2081     /* Empty or NULL string gets treated as "." */
2082     if (path == NULL || *path == '\0') {
2083 	bname[0] = '.';
2084 	bname[1] = '\0';
2085 	return (0);
2086     }
2087 
2088     /* Strip trailing slashes */
2089     endp = path + strlen(path) - 1;
2090     while (endp > path && *endp == '/')
2091 	endp--;
2092 
2093     /* Find the start of the dir */
2094     while (endp > path && *endp != '/')
2095 	endp--;
2096 
2097     /* Either the dir is "/" or there are no slashes */
2098     if (endp == path) {
2099 	bname[0] = *endp == '/' ? '/' : '.';
2100 	bname[1] = '\0';
2101 	return (0);
2102     } else {
2103 	do {
2104 	    endp--;
2105 	} while (endp > path && *endp == '/');
2106     }
2107 
2108     if (endp - path + 2 > PATH_MAX)
2109     {
2110 	_rtld_error("Filename is too long: %s", path);
2111 	return(-1);
2112     }
2113 
2114     strncpy(bname, path, endp - path + 1);
2115     bname[endp - path + 1] = '\0';
2116     return (0);
2117 }
2118 
2119 static void
2120 linkmap_add(Obj_Entry *obj)
2121 {
2122     struct link_map *l = &obj->linkmap;
2123     struct link_map *prev;
2124 
2125     obj->linkmap.l_name = obj->path;
2126     obj->linkmap.l_addr = obj->mapbase;
2127     obj->linkmap.l_ld = obj->dynamic;
2128 #ifdef __mips__
2129     /* GDB needs load offset on MIPS to use the symbols */
2130     obj->linkmap.l_offs = obj->relocbase;
2131 #endif
2132 
2133     if (r_debug.r_map == NULL) {
2134 	r_debug.r_map = l;
2135 	return;
2136     }
2137 
2138     /*
2139      * Scan to the end of the list, but not past the entry for the
2140      * dynamic linker, which we want to keep at the very end.
2141      */
2142     for (prev = r_debug.r_map;
2143       prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
2144       prev = prev->l_next)
2145 	;
2146 
2147     /* Link in the new entry. */
2148     l->l_prev = prev;
2149     l->l_next = prev->l_next;
2150     if (l->l_next != NULL)
2151 	l->l_next->l_prev = l;
2152     prev->l_next = l;
2153 }
2154 
2155 static void
2156 linkmap_delete(Obj_Entry *obj)
2157 {
2158     struct link_map *l = &obj->linkmap;
2159 
2160     if (l->l_prev == NULL) {
2161 	if ((r_debug.r_map = l->l_next) != NULL)
2162 	    l->l_next->l_prev = NULL;
2163 	return;
2164     }
2165 
2166     if ((l->l_prev->l_next = l->l_next) != NULL)
2167 	l->l_next->l_prev = l->l_prev;
2168 }
2169 
2170 /*
2171  * Function for the debugger to set a breakpoint on to gain control.
2172  *
2173  * The two parameters allow the debugger to easily find and determine
2174  * what the runtime loader is doing and to whom it is doing it.
2175  *
2176  * When the loadhook trap is hit (r_debug_state, set at program
2177  * initialization), the arguments can be found on the stack:
2178  *
2179  *  +8   struct link_map *m
2180  *  +4   struct r_debug  *rd
2181  *  +0   RetAddr
2182  */
2183 void
2184 r_debug_state(struct r_debug* rd, struct link_map *m)
2185 {
2186 }
2187 
2188 /*
2189  * Get address of the pointer variable in the main program.
2190  */
2191 static const void **
2192 get_program_var_addr(const char *name)
2193 {
2194     const Obj_Entry *obj;
2195     unsigned long hash;
2196 
2197     hash = elf_hash(name);
2198     for (obj = obj_main;  obj != NULL;  obj = obj->next) {
2199 	const Elf_Sym *def;
2200 
2201 	if ((def = symlook_obj(name, hash, obj, false)) != NULL) {
2202 	    const void **addr;
2203 
2204 	    addr = (const void **)(obj->relocbase + def->st_value);
2205 	    return addr;
2206 	}
2207     }
2208     return NULL;
2209 }
2210 
2211 /*
2212  * Set a pointer variable in the main program to the given value.  This
2213  * is used to set key variables such as "environ" before any of the
2214  * init functions are called.
2215  */
2216 static void
2217 set_program_var(const char *name, const void *value)
2218 {
2219     const void **addr;
2220 
2221     if ((addr = get_program_var_addr(name)) != NULL) {
2222 	dbg("\"%s\": *%p <-- %p", name, addr, value);
2223 	*addr = value;
2224     }
2225 }
2226 
2227 /*
2228  * This is a special version of getenv which is far more efficient
2229  * at finding LD_ environment vars.
2230  */
2231 static
2232 const char *
2233 _getenv_ld(const char *id)
2234 {
2235     const char *envp;
2236     int i, j;
2237     int idlen = strlen(id);
2238 
2239     if (ld_index == LD_ARY_CACHE)
2240 	return(getenv(id));
2241     if (ld_index == 0) {
2242 	for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) {
2243 	    if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_')
2244 		ld_ary[j++] = envp;
2245 	}
2246 	if (j == 0)
2247 		ld_ary[j++] = "";
2248 	ld_index = j;
2249     }
2250     for (i = ld_index - 1; i >= 0; --i) {
2251 	if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=')
2252 	    return(ld_ary[i] + idlen + 1);
2253     }
2254     return(NULL);
2255 }
2256 
2257 /*
2258  * Given a symbol name in a referencing object, find the corresponding
2259  * definition of the symbol.  Returns a pointer to the symbol, or NULL if
2260  * no definition was found.  Returns a pointer to the Obj_Entry of the
2261  * defining object via the reference parameter DEFOBJ_OUT.
2262  */
2263 static const Elf_Sym *
2264 symlook_default(const char *name, unsigned long hash,
2265     const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt)
2266 {
2267     DoneList donelist;
2268     const Elf_Sym *def;
2269     const Elf_Sym *symp;
2270     const Obj_Entry *obj;
2271     const Obj_Entry *defobj;
2272     const Objlist_Entry *elm;
2273     def = NULL;
2274     defobj = NULL;
2275     donelist_init(&donelist);
2276 
2277     /* Look first in the referencing object if linked symbolically. */
2278     if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
2279 	symp = symlook_obj(name, hash, refobj, in_plt);
2280 	if (symp != NULL) {
2281 	    def = symp;
2282 	    defobj = refobj;
2283 	}
2284     }
2285 
2286     /* Search all objects loaded at program start up. */
2287     if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2288 	symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist);
2289 	if (symp != NULL &&
2290 	  (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2291 	    def = symp;
2292 	    defobj = obj;
2293 	}
2294     }
2295 
2296     /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
2297     STAILQ_FOREACH(elm, &list_global, link) {
2298        if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2299            break;
2300        symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
2301          &donelist);
2302 	if (symp != NULL &&
2303 	  (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2304 	    def = symp;
2305 	    defobj = obj;
2306 	}
2307     }
2308 
2309     /* Search all dlopened DAGs containing the referencing object. */
2310     STAILQ_FOREACH(elm, &refobj->dldags, link) {
2311 	if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2312 	    break;
2313 	symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
2314 	  &donelist);
2315 	if (symp != NULL &&
2316 	  (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2317 	    def = symp;
2318 	    defobj = obj;
2319 	}
2320     }
2321 
2322     /*
2323      * Search the dynamic linker itself, and possibly resolve the
2324      * symbol from there.  This is how the application links to
2325      * dynamic linker services such as dlopen.  Only the values listed
2326      * in the "exports" array can be resolved from the dynamic linker.
2327      */
2328     if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2329 	symp = symlook_obj(name, hash, &obj_rtld, in_plt);
2330 	if (symp != NULL && is_exported(symp)) {
2331 	    def = symp;
2332 	    defobj = &obj_rtld;
2333 	}
2334     }
2335 
2336     if (def != NULL)
2337 	*defobj_out = defobj;
2338     return def;
2339 }
2340 
2341 static const Elf_Sym *
2342 symlook_list(const char *name, unsigned long hash, Objlist *objlist,
2343   const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp)
2344 {
2345     const Elf_Sym *symp;
2346     const Elf_Sym *def;
2347     const Obj_Entry *defobj;
2348     const Objlist_Entry *elm;
2349 
2350     def = NULL;
2351     defobj = NULL;
2352     STAILQ_FOREACH(elm, objlist, link) {
2353 	if (donelist_check(dlp, elm->obj))
2354 	    continue;
2355 	if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) {
2356 	    if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) {
2357 		def = symp;
2358 		defobj = elm->obj;
2359 		if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2360 		    break;
2361 	    }
2362 	}
2363     }
2364     if (def != NULL)
2365 	*defobj_out = defobj;
2366     return def;
2367 }
2368 
2369 /*
2370  * Search the symbol table of a single shared object for a symbol of
2371  * the given name.  Returns a pointer to the symbol, or NULL if no
2372  * definition was found.
2373  *
2374  * The symbol's hash value is passed in for efficiency reasons; that
2375  * eliminates many recomputations of the hash value.
2376  */
2377 const Elf_Sym *
2378 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj,
2379   bool in_plt)
2380 {
2381     if (obj->buckets != NULL) {
2382 	unsigned long symnum = obj->buckets[hash % obj->nbuckets];
2383 
2384 	while (symnum != STN_UNDEF) {
2385 	    const Elf_Sym *symp;
2386 	    const char *strp;
2387 
2388 	    if (symnum >= obj->nchains)
2389 		return NULL;	/* Bad object */
2390 	    symp = obj->symtab + symnum;
2391 	    strp = obj->strtab + symp->st_name;
2392 
2393 	    if (name[0] == strp[0] && strcmp(name, strp) == 0)
2394 		return symp->st_shndx != SHN_UNDEF ||
2395 		  (!in_plt && symp->st_value != 0 &&
2396 		  ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL;
2397 
2398 	    symnum = obj->chains[symnum];
2399 	}
2400     }
2401     return NULL;
2402 }
2403 
2404 static void
2405 trace_loaded_objects(Obj_Entry *obj)
2406 {
2407     const char *fmt1, *fmt2, *fmt, *main_local;
2408     int		c;
2409 
2410     if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
2411 	main_local = "";
2412 
2413     if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
2414 	fmt1 = "\t%o => %p (%x)\n";
2415 
2416     if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
2417 	fmt2 = "\t%o (%x)\n";
2418 
2419     for (; obj; obj = obj->next) {
2420 	Needed_Entry		*needed;
2421 	char			*name, *path;
2422 	bool			is_lib;
2423 
2424 	for (needed = obj->needed; needed; needed = needed->next) {
2425 	    if (needed->obj != NULL) {
2426 		if (needed->obj->traced)
2427 		    continue;
2428 		needed->obj->traced = true;
2429 		path = needed->obj->path;
2430 	    } else
2431 		path = "not found";
2432 
2433 	    name = (char *)obj->strtab + needed->name;
2434 	    is_lib = strncmp(name, "lib", 3) == 0;	/* XXX - bogus */
2435 
2436 	    fmt = is_lib ? fmt1 : fmt2;
2437 	    while ((c = *fmt++) != '\0') {
2438 		switch (c) {
2439 		default:
2440 		    putchar(c);
2441 		    continue;
2442 		case '\\':
2443 		    switch (c = *fmt) {
2444 		    case '\0':
2445 			continue;
2446 		    case 'n':
2447 			putchar('\n');
2448 			break;
2449 		    case 't':
2450 			putchar('\t');
2451 			break;
2452 		    }
2453 		    break;
2454 		case '%':
2455 		    switch (c = *fmt) {
2456 		    case '\0':
2457 			continue;
2458 		    case '%':
2459 		    default:
2460 			putchar(c);
2461 			break;
2462 		    case 'A':
2463 			printf("%s", main_local);
2464 			break;
2465 		    case 'a':
2466 			printf("%s", obj_main->path);
2467 			break;
2468 		    case 'o':
2469 			printf("%s", name);
2470 			break;
2471 #if 0
2472 		    case 'm':
2473 			printf("%d", sodp->sod_major);
2474 			break;
2475 		    case 'n':
2476 			printf("%d", sodp->sod_minor);
2477 			break;
2478 #endif
2479 		    case 'p':
2480 			printf("%s", path);
2481 			break;
2482 		    case 'x':
2483 			printf("%p", needed->obj ? needed->obj->mapbase : 0);
2484 			break;
2485 		    }
2486 		    break;
2487 		}
2488 		++fmt;
2489 	    }
2490 	}
2491     }
2492 }
2493 
2494 /*
2495  * Unload a dlopened object and its dependencies from memory and from
2496  * our data structures.  It is assumed that the DAG rooted in the
2497  * object has already been unreferenced, and that the object has a
2498  * reference count of 0.
2499  */
2500 static void
2501 unload_object(Obj_Entry *root)
2502 {
2503     Obj_Entry *obj;
2504     Obj_Entry **linkp;
2505 
2506     assert(root->refcount == 0);
2507 
2508     /*
2509      * Pass over the DAG removing unreferenced objects from
2510      * appropriate lists.
2511      */
2512     unlink_object(root);
2513 
2514     /* Unmap all objects that are no longer referenced. */
2515     linkp = &obj_list->next;
2516     while ((obj = *linkp) != NULL) {
2517 	if (obj->refcount == 0) {
2518 	    dbg("unloading \"%s\"", obj->path);
2519 	    munmap(obj->mapbase, obj->mapsize);
2520 	    linkmap_delete(obj);
2521 	    *linkp = obj->next;
2522 	    obj_count--;
2523 	    obj_free(obj);
2524 	} else
2525 	    linkp = &obj->next;
2526     }
2527     obj_tail = linkp;
2528 }
2529 
2530 static void
2531 unlink_object(Obj_Entry *root)
2532 {
2533     const Needed_Entry *needed;
2534     Objlist_Entry *elm;
2535 
2536     if (root->refcount == 0) {
2537 	/* Remove the object from the RTLD_GLOBAL list. */
2538 	objlist_remove(&list_global, root);
2539 
2540     	/* Remove the object from all objects' DAG lists. */
2541     	STAILQ_FOREACH(elm, &root->dagmembers , link)
2542 	    objlist_remove(&elm->obj->dldags, root);
2543     }
2544 
2545     for (needed = root->needed;  needed != NULL;  needed = needed->next)
2546 	if (needed->obj != NULL)
2547 	    unlink_object(needed->obj);
2548 }
2549 
2550 static void
2551 unref_dag(Obj_Entry *root)
2552 {
2553     const Needed_Entry *needed;
2554 
2555     if (root->refcount == 0)
2556 	return;
2557     root->refcount--;
2558     if (root->refcount == 0)
2559 	for (needed = root->needed;  needed != NULL;  needed = needed->next)
2560 	    if (needed->obj != NULL)
2561 		unref_dag(needed->obj);
2562 }
2563 
2564 /*
2565  * Common code for MD __tls_get_addr().
2566  */
2567 void *
2568 tls_get_addr_common(void **dtvp, int index, size_t offset)
2569 {
2570     Elf_Addr* dtv = *dtvp;
2571 
2572     /* Check dtv generation in case new modules have arrived */
2573     if (dtv[0] != tls_dtv_generation) {
2574 	Elf_Addr* newdtv;
2575 	int to_copy;
2576 
2577 	wlock_acquire();
2578 
2579 	newdtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr));
2580 	to_copy = dtv[1];
2581 	if (to_copy > tls_max_index)
2582 	    to_copy = tls_max_index;
2583 	memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr));
2584 	newdtv[0] = tls_dtv_generation;
2585 	newdtv[1] = tls_max_index;
2586 	free(dtv);
2587 	*dtvp = newdtv;
2588 
2589 	wlock_release();
2590     }
2591 
2592     /* Dynamically allocate module TLS if necessary */
2593     if (!dtv[index + 1]) {
2594 	/* XXX
2595 	 * here we should avoid to be re-entered by signal handler
2596 	 * code, I assume wlock_acquire will masked all signals,
2597 	 * otherwise there is race and dead lock thread itself.
2598 	 */
2599 	wlock_acquire();
2600     	if (!dtv[index + 1])
2601 	    dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
2602 	wlock_release();
2603     }
2604 
2605     return (void*) (dtv[index + 1] + offset);
2606 }
2607 
2608 #if defined(RTLD_STATIC_TLS_VARIANT_II)
2609 
2610 /*
2611  * Allocate the static TLS area.  Return a pointer to the TCB.  The
2612  * static area is based on negative offsets relative to the tcb.
2613  *
2614  * The TCB contains an errno pointer for the system call layer, but because
2615  * we are the RTLD we really have no idea how the caller was compiled so
2616  * the information has to be passed in.  errno can either be:
2617  *
2618  *	type 0	errno is a simple non-TLS global pointer.
2619  *		(special case for e.g. libc_rtld)
2620  *	type 1	errno accessed by GOT entry	(dynamically linked programs)
2621  *	type 2	errno accessed by %gs:OFFSET	(statically linked programs)
2622  */
2623 struct tls_tcb *
2624 allocate_tls(Obj_Entry *objs)
2625 {
2626     Obj_Entry *obj;
2627     size_t data_size;
2628     size_t dtv_size;
2629     struct tls_tcb *tcb;
2630     Elf_Addr *dtv;
2631     Elf_Addr addr;
2632 
2633     /*
2634      * Allocate the new TCB.  static TLS storage is placed just before the
2635      * TCB to support the %gs:OFFSET (negative offset) model.
2636      */
2637     data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
2638 		~RTLD_STATIC_TLS_ALIGN_MASK;
2639     tcb = malloc(data_size + sizeof(*tcb));
2640     tcb = (void *)((char *)tcb + data_size);	/* actual tcb location */
2641 
2642     dtv_size = (tls_max_index + 2) * sizeof(Elf_Addr);
2643     dtv = malloc(dtv_size);
2644     bzero(dtv, dtv_size);
2645 
2646 #ifdef RTLD_TCB_HAS_SELF_POINTER
2647     tcb->tcb_self = tcb;
2648 #endif
2649     tcb->tcb_dtv = dtv;
2650     tcb->tcb_pthread = NULL;
2651 
2652     dtv[0] = tls_dtv_generation;
2653     dtv[1] = tls_max_index;
2654 
2655     for (obj = objs; obj; obj = obj->next) {
2656 	if (obj->tlsoffset) {
2657 	    addr = (Elf_Addr)tcb - obj->tlsoffset;
2658 	    memset((void *)(addr + obj->tlsinitsize),
2659 		   0, obj->tlssize - obj->tlsinitsize);
2660 	    if (obj->tlsinit)
2661 		memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
2662 	    dtv[obj->tlsindex + 1] = addr;
2663 	}
2664     }
2665     return(tcb);
2666 }
2667 
2668 void
2669 free_tls(struct tls_tcb *tcb)
2670 {
2671     Elf_Addr *dtv;
2672     int dtv_size, i;
2673     Elf_Addr tls_start, tls_end;
2674     size_t data_size;
2675 
2676     data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
2677 		~RTLD_STATIC_TLS_ALIGN_MASK;
2678     dtv = tcb->tcb_dtv;
2679     dtv_size = dtv[1];
2680     tls_end = (Elf_Addr)tcb;
2681     tls_start = (Elf_Addr)tcb - data_size;
2682     for (i = 0; i < dtv_size; i++) {
2683 	if (dtv[i+2] != NULL && (dtv[i+2] < tls_start || dtv[i+2] > tls_end)) {
2684 	    free((void *)dtv[i+2]);
2685 	}
2686     }
2687     free((void *)tls_start);
2688 }
2689 
2690 #else
2691 #error "Unsupported TLS layout"
2692 #endif
2693 
2694 /*
2695  * Allocate TLS block for module with given index.
2696  */
2697 void *
2698 allocate_module_tls(int index)
2699 {
2700     Obj_Entry* obj;
2701     char* p;
2702 
2703     for (obj = obj_list; obj; obj = obj->next) {
2704 	if (obj->tlsindex == index)
2705 	    break;
2706     }
2707     if (!obj) {
2708 	_rtld_error("Can't find module with TLS index %d", index);
2709 	die();
2710     }
2711 
2712     p = malloc(obj->tlssize);
2713     memcpy(p, obj->tlsinit, obj->tlsinitsize);
2714     memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
2715 
2716     return p;
2717 }
2718 
2719 bool
2720 allocate_tls_offset(Obj_Entry *obj)
2721 {
2722     size_t off;
2723 
2724     if (obj->tls_done)
2725 	return true;
2726 
2727     if (obj->tlssize == 0) {
2728 	obj->tls_done = true;
2729 	return true;
2730     }
2731 
2732     if (obj->tlsindex == 1)
2733 	off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign);
2734     else
2735 	off = calculate_tls_offset(tls_last_offset, tls_last_size,
2736 				   obj->tlssize, obj->tlsalign);
2737 
2738     /*
2739      * If we have already fixed the size of the static TLS block, we
2740      * must stay within that size. When allocating the static TLS, we
2741      * leave a small amount of space spare to be used for dynamically
2742      * loading modules which use static TLS.
2743      */
2744     if (tls_static_space) {
2745 	if (calculate_tls_end(off, obj->tlssize) > tls_static_space)
2746 	    return false;
2747     }
2748 
2749     tls_last_offset = obj->tlsoffset = off;
2750     tls_last_size = obj->tlssize;
2751     obj->tls_done = true;
2752 
2753     return true;
2754 }
2755 
2756 void
2757 free_tls_offset(Obj_Entry *obj)
2758 {
2759 #ifdef RTLD_STATIC_TLS_VARIANT_II
2760     /*
2761      * If we were the last thing to allocate out of the static TLS
2762      * block, we give our space back to the 'allocator'. This is a
2763      * simplistic workaround to allow libGL.so.1 to be loaded and
2764      * unloaded multiple times. We only handle the Variant II
2765      * mechanism for now - this really needs a proper allocator.
2766      */
2767     if (calculate_tls_end(obj->tlsoffset, obj->tlssize)
2768 	== calculate_tls_end(tls_last_offset, tls_last_size)) {
2769 	tls_last_offset -= obj->tlssize;
2770 	tls_last_size = 0;
2771     }
2772 #endif
2773 }
2774 
2775 struct tls_tcb *
2776 _rtld_allocate_tls(void)
2777 {
2778     struct tls_tcb *new_tcb;
2779 
2780     wlock_acquire();
2781     new_tcb = allocate_tls(obj_list);
2782     wlock_release();
2783 
2784     return (new_tcb);
2785 }
2786 
2787 void
2788 _rtld_free_tls(struct tls_tcb *tcb)
2789 {
2790     wlock_acquire();
2791     free_tls(tcb);
2792     wlock_release();
2793 }
2794 
2795