libexec/rtld-elf/rtld.c

   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 1.29 2008/01/08 00:02:04 corecode 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 *, int);
  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, Obj_Entry *);
 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   const Objlist *, const Obj_Entry **, bool in_plt, DoneList *);
 129 static const Elf_Sym *symlook_needed(const char *, unsigned long,
 130   const Needed_Entry *, const Obj_Entry **, bool in_plt, DoneList *);
 131 static void trace_loaded_objects(Obj_Entry *obj);
 132 static void unlink_object(Obj_Entry *);
 133 static void unload_object(Obj_Entry *);
 134 static void unref_dag(Obj_Entry *);
 135
 136 void r_debug_state(struct r_debug*, struct link_map*);
 137
 138 /*
 139  * Data declarations.
 140  */
 141 static char *error_message;     /* Message for dlerror(), or NULL */
 142 struct r_debug r_debug;         /* for GDB; */
 143 static bool trust;              /* False for setuid and setgid programs */
 144 static const char *ld_bind_now; /* Environment variable for immediate binding */
 145 static const char *ld_debug;    /* Environment variable for debugging */
 146 static const char *ld_library_path; /* Environment variable for search path */
 147 static char *ld_preload;        /* Environment variable for libraries to
 148                                    load first */
 149 static const char *ld_tracing;  /* Called from ldd(1) to print libs */
 150                                 /* Optional function call tracing hook */
 151 static int (*rtld_functrace)(const char *caller_obj,
 152                              const char *callee_obj,
 153                              const char *callee_func,
 154                              void *stack);
 155 static Obj_Entry *rtld_functrace_obj;   /* Object thereof */
 156 static Obj_Entry *obj_list;     /* Head of linked list of shared objects */
 157 static Obj_Entry **obj_tail;    /* Link field of last object in list */
 158 static Obj_Entry **preload_tail;
 159 static Obj_Entry *obj_main;     /* The main program shared object */
 160 static Obj_Entry obj_rtld;      /* The dynamic linker shared object */
 161 static unsigned int obj_count;  /* Number of objects in obj_list */
 162 static int      ld_resident;    /* Non-zero if resident */
 163 static const char *ld_ary[LD_ARY_CACHE];
 164 static int      ld_index;
 165 static Objlist initlist;
 166
 167 static Objlist list_global =    /* Objects dlopened with RTLD_GLOBAL */
 168   STAILQ_HEAD_INITIALIZER(list_global);
 169 static Objlist list_main =      /* Objects loaded at program startup */
 170   STAILQ_HEAD_INITIALIZER(list_main);
 171 static Objlist list_fini =      /* Objects needing fini() calls */
 172   STAILQ_HEAD_INITIALIZER(list_fini);
 173
 174 static LockInfo lockinfo;
 175
 176 static Elf_Sym sym_zero;        /* For resolving undefined weak refs. */
 177
 178 #define GDB_STATE(s,m)  r_debug.r_state = s; r_debug_state(&r_debug,m);
 179
 180 extern Elf_Dyn _DYNAMIC;
 181 #pragma weak _DYNAMIC
 182
 183 /*
 184  * These are the functions the dynamic linker exports to application
 185  * programs.  They are the only symbols the dynamic linker is willing
 186  * to export from itself.
 187  */
 188 static func_ptr_type exports[] = {
 189     (func_ptr_type) &_rtld_error,
 190     (func_ptr_type) &dlclose,
 191     (func_ptr_type) &dlerror,
 192     (func_ptr_type) &dlopen,
 193     (func_ptr_type) &dlsym,
 194     (func_ptr_type) &dladdr,
 195     (func_ptr_type) &dlinfo,
 196 #ifdef __i386__
 197     (func_ptr_type) &___tls_get_addr,
 198 #endif
 199     (func_ptr_type) &__tls_get_addr,
 200     (func_ptr_type) &__tls_get_addr_tcb,
 201     (func_ptr_type) &_rtld_allocate_tls,
 202     (func_ptr_type) &_rtld_free_tls,
 203     (func_ptr_type) &_rtld_call_init,
 204     NULL
 205 };
 206
 207 /*
 208  * Global declarations normally provided by crt1.  The dynamic linker is
 209  * not built with crt1, so we have to provide them ourselves.
 210  */
 211 char *__progname;
 212 char **environ;
 213
 214 /*
 215  * Globals to control TLS allocation.
 216  */
 217 size_t tls_last_offset;         /* Static TLS offset of last module */
 218 size_t tls_last_size;           /* Static TLS size of last module */
 219 size_t tls_static_space;        /* Static TLS space allocated */
 220 int tls_dtv_generation = 1;     /* Used to detect when dtv size changes  */
 221 int tls_max_index = 1;          /* Largest module index allocated */
 222
 223 /*
 224  * Fill in a DoneList with an allocation large enough to hold all of
 225  * the currently-loaded objects.  Keep this as a macro since it calls
 226  * alloca and we want that to occur within the scope of the caller.
 227  */
 228 #define donelist_init(dlp)                                      \
 229     ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]),   \
 230     assert((dlp)->objs != NULL),                                \
 231     (dlp)->num_alloc = obj_count,                               \
 232     (dlp)->num_used = 0)
 233
 234 static __inline void
 235 rlock_acquire(void)
 236 {
 237     lockinfo.rlock_acquire(lockinfo.thelock);
 238     atomic_incr_int(&lockinfo.rcount);
 239     lock_check();
 240 }
 241
 242 static __inline void
 243 wlock_acquire(void)
 244 {
 245     lockinfo.wlock_acquire(lockinfo.thelock);
 246     atomic_incr_int(&lockinfo.wcount);
 247     lock_check();
 248 }
 249
 250 static __inline void
 251 rlock_release(void)
 252 {
 253     atomic_decr_int(&lockinfo.rcount);
 254     lockinfo.rlock_release(lockinfo.thelock);
 255 }
 256
 257 static __inline void
 258 wlock_release(void)
 259 {
 260     atomic_decr_int(&lockinfo.wcount);
 261     lockinfo.wlock_release(lockinfo.thelock);
 262 }
 263
 264 /*
 265  * Main entry point for dynamic linking.  The first argument is the
 266  * stack pointer.  The stack is expected to be laid out as described
 267  * in the SVR4 ABI specification, Intel 386 Processor Supplement.
 268  * Specifically, the stack pointer points to a word containing
 269  * ARGC.  Following that in the stack is a null-terminated sequence
 270  * of pointers to argument strings.  Then comes a null-terminated
 271  * sequence of pointers to environment strings.  Finally, there is a
 272  * sequence of "auxiliary vector" entries.
 273  *
 274  * The second argument points to a place to store the dynamic linker's
 275  * exit procedure pointer and the third to a place to store the main
 276  * program's object.
 277  *
 278  * The return value is the main program's entry point.
 279  */
 280
 281 func_ptr_type
 282 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
 283 {
 284     Elf_Auxinfo *aux_info[AT_COUNT];
 285     int i;
 286     int argc;
 287     char **argv;
 288     char **env;
 289     Elf_Auxinfo *aux;
 290     Elf_Auxinfo *auxp;
 291     const char *argv0;
 292     Objlist_Entry *entry;
 293     Obj_Entry *obj;
 294
 295     ld_index = 0;       /* don't use old env cache in case we are resident */
 296
 297     /*
 298      * On entry, the dynamic linker itself has not been relocated yet.
 299      * Be very careful not to reference any global data until after
 300      * init_rtld has returned.  It is OK to reference file-scope statics
 301      * and string constants, and to call static and global functions.
 302      */
 303
 304     /* Find the auxiliary vector on the stack. */
 305     argc = *sp++;
 306     argv = (char **) sp;
 307     sp += argc + 1;     /* Skip over arguments and NULL terminator */
 308     env = (char **) sp;
 309
 310     /*
 311      * If we aren't already resident we have to dig out some more info.
 312      * Note that auxinfo does not exist when we are resident.
 313      */
 314     if (ld_resident == 0) {
 315         while (*sp++ != 0)      /* Skip over environment, and NULL terminator */
 316             ;
 317         aux = (Elf_Auxinfo *) sp;
 318
 319         /* Digest the auxiliary vector. */
 320         for (i = 0;  i < AT_COUNT;  i++)
 321             aux_info[i] = NULL;
 322         for (auxp = aux;  auxp->a_type != AT_NULL;  auxp++) {
 323             if (auxp->a_type < AT_COUNT)
 324                 aux_info[auxp->a_type] = auxp;
 325         }
 326
 327         /* Initialize and relocate ourselves. */
 328         assert(aux_info[AT_BASE] != NULL);
 329         init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
 330     }
 331
 332     __progname = obj_rtld.path;
 333     argv0 = argv[0] != NULL ? argv[0] : "(null)";
 334     environ = env;
 335
 336     trust = (geteuid() == getuid()) && (getegid() == getgid());
 337
 338     ld_bind_now = _getenv_ld("LD_BIND_NOW");
 339     if (trust) {
 340         ld_debug = _getenv_ld("LD_DEBUG");
 341         ld_library_path = _getenv_ld("LD_LIBRARY_PATH");
 342         ld_preload = (char *)_getenv_ld("LD_PRELOAD");
 343     }
 344     ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS");
 345
 346     if (ld_debug != NULL && *ld_debug != '\0')
 347         debug = 1;
 348     dbg("%s is initialized, base address = %p", __progname,
 349         (caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
 350     dbg("RTLD dynamic = %p", obj_rtld.dynamic);
 351     dbg("RTLD pltgot  = %p", obj_rtld.pltgot);
 352
 353     /*
 354      * If we are resident we can skip work that we have already done.
 355      * Note that the stack is reset and there is no Elf_Auxinfo
 356      * when running from a resident image, and the static globals setup
 357      * between here and resident_skip will have already been setup.
 358      */
 359     if (ld_resident)
 360         goto resident_skip1;
 361
 362     /*
 363      * Load the main program, or process its program header if it is
 364      * already loaded.
 365      */
 366     if (aux_info[AT_EXECFD] != NULL) {  /* Load the main program. */
 367         int fd = aux_info[AT_EXECFD]->a_un.a_val;
 368         dbg("loading main program");
 369         obj_main = map_object(fd, argv0, NULL);
 370         close(fd);
 371         if (obj_main == NULL)
 372             die();
 373     } else {                            /* Main program already loaded. */
 374         const Elf_Phdr *phdr;
 375         int phnum;
 376         caddr_t entry;
 377
 378         dbg("processing main program's program header");
 379         assert(aux_info[AT_PHDR] != NULL);
 380         phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
 381         assert(aux_info[AT_PHNUM] != NULL);
 382         phnum = aux_info[AT_PHNUM]->a_un.a_val;
 383         assert(aux_info[AT_PHENT] != NULL);
 384         assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
 385         assert(aux_info[AT_ENTRY] != NULL);
 386         entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
 387         if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
 388             die();
 389     }
 390
 391     obj_main->path = xstrdup(argv0);
 392     obj_main->mainprog = true;
 393
 394     /*
 395      * Get the actual dynamic linker pathname from the executable if
 396      * possible.  (It should always be possible.)  That ensures that
 397      * gdb will find the right dynamic linker even if a non-standard
 398      * one is being used.
 399      */
 400     if (obj_main->interp != NULL &&
 401       strcmp(obj_main->interp, obj_rtld.path) != 0) {
 402         free(obj_rtld.path);
 403         obj_rtld.path = xstrdup(obj_main->interp);
 404         __progname = obj_rtld.path;
 405     }
 406
 407     digest_dynamic(obj_main, 0);
 408
 409     linkmap_add(obj_main);
 410     linkmap_add(&obj_rtld);
 411
 412     /* Link the main program into the list of objects. */
 413     *obj_tail = obj_main;
 414     obj_tail = &obj_main->next;
 415     obj_count++;
 416     obj_main->refcount++;
 417     /* Make sure we don't call the main program's init and fini functions. */
 418     obj_main->init = obj_main->fini = NULL;
 419
 420     /* Initialize a fake symbol for resolving undefined weak references. */
 421     sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
 422     sym_zero.st_shndx = SHN_ABS;
 423
 424     dbg("loading LD_PRELOAD libraries");
 425     if (load_preload_objects() == -1)
 426         die();
 427     preload_tail = obj_tail;
 428
 429     dbg("loading needed objects");
 430     if (load_needed_objects(obj_main) == -1)
 431         die();
 432
 433     /* Make a list of all objects loaded at startup. */
 434     for (obj = obj_list;  obj != NULL;  obj = obj->next)
 435         objlist_push_tail(&list_main, obj);
 436
 437 resident_skip1:
 438
 439     if (ld_tracing) {           /* We're done */
 440         trace_loaded_objects(obj_main);
 441         exit(0);
 442     }
 443
 444     if (ld_resident)            /* XXX clean this up! */
 445         goto resident_skip2;
 446
 447     if (getenv("LD_DUMP_REL_PRE") != NULL) {
 448        dump_relocations(obj_main);
 449        exit (0);
 450     }
 451
 452     /* setup TLS for main thread */
 453     dbg("initializing initial thread local storage");
 454     STAILQ_FOREACH(entry, &list_main, link) {
 455         /*
 456          * Allocate all the initial objects out of the static TLS
 457          * block even if they didn't ask for it.
 458          */
 459         allocate_tls_offset(entry->obj);
 460     }
 461
 462     tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA;
 463
 464     /*
 465      * Do not try to allocate the TLS here, let libc do it itself.
 466      * (crt1 for the program will call _init_tls())
 467      */
 468
 469     if (relocate_objects(obj_main,
 470         ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld) == -1)
 471         die();
 472
 473     dbg("doing copy relocations");
 474     if (do_copy_relocations(obj_main) == -1)
 475         die();
 476
 477 resident_skip2:
 478
 479     if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) {
 480         if (exec_sys_unregister(-1) < 0) {
 481             dbg("exec_sys_unregister failed %d\n", errno);
 482             exit(errno);
 483         }
 484         dbg("exec_sys_unregister success\n");
 485         exit(0);
 486     }
 487
 488     if (getenv("LD_DUMP_REL_POST") != NULL) {
 489        dump_relocations(obj_main);
 490        exit (0);
 491     }
 492
 493     dbg("initializing key program variables");
 494     set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
 495     set_program_var("environ", env);
 496
 497     if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) {
 498         extern void resident_start(void);
 499         ld_resident = 1;
 500         if (exec_sys_register(resident_start) < 0) {
 501             dbg("exec_sys_register failed %d\n", errno);
 502             exit(errno);
 503         }
 504         dbg("exec_sys_register success\n");
 505         exit(0);
 506     }
 507
 508     dbg("initializing thread locks");
 509     lockdflt_init(&lockinfo);
 510     lockinfo.thelock = lockinfo.lock_create(lockinfo.context);
 511
 512     /* Make a list of init functions to call. */
 513     objlist_init(&initlist);
 514     initlist_add_objects(obj_list, preload_tail, &initlist);
 515
 516     r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
 517
 518     /*
 519      * Do NOT call the initlist here, give libc a chance to set up
 520      * the initial TLS segment.  crt1 will then call _rtld_call_init().
 521      */
 522
 523     dbg("transferring control to program entry point = %p", obj_main->entry);
 524
 525     /* Return the exit procedure and the program entry point. */
 526     *exit_proc = rtld_exit;
 527     *objp = obj_main;
 528     return (func_ptr_type) obj_main->entry;
 529 }
 530
 531 /*
 532  * Call the initialization list for dynamically loaded libraries.
 533  * (called from crt1.c).
 534  */
 535 void
 536 _rtld_call_init(void)
 537 {
 538     objlist_call_init(&initlist);
 539     wlock_acquire();
 540     objlist_clear(&initlist);
 541     wlock_release();
 542 }
 543
 544 Elf_Addr
 545 _rtld_bind(Obj_Entry *obj, Elf_Word reloff, void *stack)
 546 {
 547     const Elf_Rel *rel;
 548     const Elf_Sym *def;
 549     const Obj_Entry *defobj;
 550     Elf_Addr *where;
 551     Elf_Addr target;
 552     int do_reloc = 1;
 553
 554     rlock_acquire();
 555     if (obj->pltrel)
 556         rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
 557     else
 558         rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
 559
 560     where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
 561     def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL);
 562     if (def == NULL)
 563         die();
 564
 565     target = (Elf_Addr)(defobj->relocbase + def->st_value);
 566
 567     dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
 568       defobj->strtab + def->st_name, basename(obj->path),
 569       (void *)target, basename(defobj->path));
 570     rlock_release();
 571
 572     /*
 573      * If we have a function call tracing hook, and the
 574      * hook would like to keep tracing this one function,
 575      * prevent the relocation so we will wind up here
 576      * the next time again.
 577      *
 578      * We don't want to functrace calls from the functracer
 579      * to avoid recursive loops.
 580      */
 581     if (rtld_functrace != NULL && obj != rtld_functrace_obj) {
 582         if (rtld_functrace(obj->path,
 583                            defobj->path,
 584                            defobj->strtab + def->st_name,
 585                            stack))
 586             do_reloc = 0;
 587     }
 588
 589     if (do_reloc)
 590         reloc_jmpslot(where, target);
 591     return target;
 592 }
 593
 594 /*
 595  * Error reporting function.  Use it like printf.  If formats the message
 596  * into a buffer, and sets things up so that the next call to dlerror()
 597  * will return the message.
 598  */
 599 void
 600 _rtld_error(const char *fmt, ...)
 601 {
 602     static char buf[512];
 603     va_list ap;
 604
 605     va_start(ap, fmt);
 606     vsnprintf(buf, sizeof buf, fmt, ap);
 607     error_message = buf;
 608     va_end(ap);
 609 }
 610
 611 /*
 612  * Return a dynamically-allocated copy of the current error message, if any.
 613  */
 614 static char *
 615 errmsg_save(void)
 616 {
 617     return error_message == NULL ? NULL : xstrdup(error_message);
 618 }
 619
 620 /*
 621  * Restore the current error message from a copy which was previously saved
 622  * by errmsg_save().  The copy is freed.
 623  */
 624 static void
 625 errmsg_restore(char *saved_msg)
 626 {
 627     if (saved_msg == NULL)
 628         error_message = NULL;
 629     else {
 630         _rtld_error("%s", saved_msg);
 631         free(saved_msg);
 632     }
 633 }
 634
 635 const char *
 636 basename(const char *name)
 637 {
 638     const char *p = strrchr(name, '/');
 639     return p != NULL ? p + 1 : name;
 640 }
 641
 642 static void
 643 die(void)
 644 {
 645     const char *msg = dlerror();
 646
 647     if (msg == NULL)
 648         msg = "Fatal error";
 649     errx(1, "%s", msg);
 650 }
 651
 652 /*
 653  * Process a shared object's DYNAMIC section, and save the important
 654  * information in its Obj_Entry structure.
 655  */
 656 static void
 657 digest_dynamic(Obj_Entry *obj, int early)
 658 {
 659     const Elf_Dyn *dynp;
 660     Needed_Entry **needed_tail = &obj->needed;
 661     const Elf_Dyn *dyn_rpath = NULL;
 662     int plttype = DT_REL;
 663
 664     for (dynp = obj->dynamic;  dynp->d_tag != DT_NULL;  dynp++) {
 665         switch (dynp->d_tag) {
 666
 667         case DT_REL:
 668             obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
 669             break;
 670
 671         case DT_RELSZ:
 672             obj->relsize = dynp->d_un.d_val;
 673             break;
 674
 675         case DT_RELENT:
 676             assert(dynp->d_un.d_val == sizeof(Elf_Rel));
 677             break;
 678
 679         case DT_JMPREL:
 680             obj->pltrel = (const Elf_Rel *)
 681               (obj->relocbase + dynp->d_un.d_ptr);
 682             break;
 683
 684         case DT_PLTRELSZ:
 685             obj->pltrelsize = dynp->d_un.d_val;
 686             break;
 687
 688         case DT_RELA:
 689             obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
 690             break;
 691
 692         case DT_RELASZ:
 693             obj->relasize = dynp->d_un.d_val;
 694             break;
 695
 696         case DT_RELAENT:
 697             assert(dynp->d_un.d_val == sizeof(Elf_Rela));
 698             break;
 699
 700         case DT_PLTREL:
 701             plttype = dynp->d_un.d_val;
 702             assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
 703             break;
 704
 705         case DT_SYMTAB:
 706             obj->symtab = (const Elf_Sym *)
 707               (obj->relocbase + dynp->d_un.d_ptr);
 708             break;
 709
 710         case DT_SYMENT:
 711             assert(dynp->d_un.d_val == sizeof(Elf_Sym));
 712             break;
 713
 714         case DT_STRTAB:
 715             obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
 716             break;
 717
 718         case DT_STRSZ:
 719             obj->strsize = dynp->d_un.d_val;
 720             break;
 721
 722         case DT_HASH:
 723             {
 724                 const Elf_Addr *hashtab = (const Elf_Addr *)
 725                   (obj->relocbase + dynp->d_un.d_ptr);
 726                 obj->nbuckets = hashtab[0];
 727                 obj->nchains = hashtab[1];
 728                 obj->buckets = hashtab + 2;
 729                 obj->chains = obj->buckets + obj->nbuckets;
 730             }
 731             break;
 732
 733         case DT_NEEDED:
 734             if (!obj->rtld) {
 735                 Needed_Entry *nep = NEW(Needed_Entry);
 736                 nep->name = dynp->d_un.d_val;
 737                 nep->obj = NULL;
 738                 nep->next = NULL;
 739
 740                 *needed_tail = nep;
 741                 needed_tail = &nep->next;
 742             }
 743             break;
 744
 745         case DT_PLTGOT:
 746             obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
 747             break;
 748
 749         case DT_TEXTREL:
 750             obj->textrel = true;
 751             break;
 752
 753         case DT_SYMBOLIC:
 754             obj->symbolic = true;
 755             break;
 756
 757         case DT_RPATH:
 758         case DT_RUNPATH:        /* XXX: process separately */
 759             /*
 760              * We have to wait until later to process this, because we
 761              * might not have gotten the address of the string table yet.
 762              */
 763             dyn_rpath = dynp;
 764             break;
 765
 766         case DT_SONAME:
 767             /* Not used by the dynamic linker. */
 768             break;
 769
 770         case DT_INIT:
 771             obj->init = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
 772             break;
 773
 774         case DT_FINI:
 775             obj->fini = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
 776             break;
 777
 778         case DT_DEBUG:
 779             /* XXX - not implemented yet */
 780             if (!early)
 781                 dbg("Filling in DT_DEBUG entry");
 782             ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
 783             break;
 784
 785         case DT_FLAGS:
 786                 if (dynp->d_un.d_val & DF_ORIGIN) {
 787                     obj->origin_path = xmalloc(PATH_MAX);
 788                     if (rtld_dirname(obj->path, obj->origin_path) == -1)
 789                         die();
 790                 }
 791                 if (dynp->d_un.d_val & DF_SYMBOLIC)
 792                     obj->symbolic = true;
 793                 if (dynp->d_un.d_val & DF_TEXTREL)
 794                     obj->textrel = true;
 795                 if (dynp->d_un.d_val & DF_BIND_NOW)
 796                     obj->bind_now = true;
 797                 if (dynp->d_un.d_val & DF_STATIC_TLS)
 798                     ;
 799             break;
 800
 801         default:
 802             if (!early)
 803                 dbg("Ignoring d_tag %d = %#x", dynp->d_tag, dynp->d_tag);
 804             break;
 805         }
 806     }
 807
 808     obj->traced = false;
 809
 810     if (plttype == DT_RELA) {
 811         obj->pltrela = (const Elf_Rela *) obj->pltrel;
 812         obj->pltrel = NULL;
 813         obj->pltrelasize = obj->pltrelsize;
 814         obj->pltrelsize = 0;
 815     }
 816
 817     if (dyn_rpath != NULL)
 818         obj->rpath = obj->strtab + dyn_rpath->d_un.d_val;
 819 }
 820
 821 /*
 822  * Process a shared object's program header.  This is used only for the
 823  * main program, when the kernel has already loaded the main program
 824  * into memory before calling the dynamic linker.  It creates and
 825  * returns an Obj_Entry structure.
 826  */
 827 static Obj_Entry *
 828 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
 829 {
 830     Obj_Entry *obj;
 831     const Elf_Phdr *phlimit = phdr + phnum;
 832     const Elf_Phdr *ph;
 833     int nsegs = 0;
 834
 835     obj = obj_new();
 836     for (ph = phdr;  ph < phlimit;  ph++) {
 837         switch (ph->p_type) {
 838
 839         case PT_PHDR:
 840             if ((const Elf_Phdr *)ph->p_vaddr != phdr) {
 841                 _rtld_error("%s: invalid PT_PHDR", path);
 842                 return NULL;
 843             }
 844             obj->phdr = (const Elf_Phdr *) ph->p_vaddr;
 845             obj->phsize = ph->p_memsz;
 846             break;
 847
 848         case PT_INTERP:
 849             obj->interp = (const char *) ph->p_vaddr;
 850             break;
 851
 852         case PT_LOAD:
 853             if (nsegs == 0) {   /* First load segment */
 854                 obj->vaddrbase = trunc_page(ph->p_vaddr);
 855                 obj->mapbase = (caddr_t) obj->vaddrbase;
 856                 obj->relocbase = obj->mapbase - obj->vaddrbase;
 857                 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
 858                   obj->vaddrbase;
 859             } else {            /* Last load segment */
 860                 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
 861                   obj->vaddrbase;
 862             }
 863             nsegs++;
 864             break;
 865
 866         case PT_DYNAMIC:
 867             obj->dynamic = (const Elf_Dyn *) ph->p_vaddr;
 868             break;
 869
 870         case PT_TLS:
 871             obj->tlsindex = 1;
 872             obj->tlssize = ph->p_memsz;
 873             obj->tlsalign = ph->p_align;
 874             obj->tlsinitsize = ph->p_filesz;
 875             obj->tlsinit = (void*) ph->p_vaddr;
 876             break;
 877         }
 878     }
 879     if (nsegs < 1) {
 880         _rtld_error("%s: too few PT_LOAD segments", path);
 881         return NULL;
 882     }
 883
 884     obj->entry = entry;
 885     return obj;
 886 }
 887
 888 static Obj_Entry *
 889 dlcheck(void *handle)
 890 {
 891     Obj_Entry *obj;
 892
 893     for (obj = obj_list;  obj != NULL;  obj = obj->next)
 894         if (obj == (Obj_Entry *) handle)
 895             break;
 896
 897     if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
 898         _rtld_error("Invalid shared object handle %p", handle);
 899         return NULL;
 900     }
 901     return obj;
 902 }
 903
 904 /*
 905  * If the given object is already in the donelist, return true.  Otherwise
 906  * add the object to the list and return false.
 907  */
 908 static bool
 909 donelist_check(DoneList *dlp, const Obj_Entry *obj)
 910 {
 911     unsigned int i;
 912
 913     for (i = 0;  i < dlp->num_used;  i++)
 914         if (dlp->objs[i] == obj)
 915             return true;
 916     /*
 917      * Our donelist allocation should always be sufficient.  But if
 918      * our threads locking isn't working properly, more shared objects
 919      * could have been loaded since we allocated the list.  That should
 920      * never happen, but we'll handle it properly just in case it does.
 921      */
 922     if (dlp->num_used < dlp->num_alloc)
 923         dlp->objs[dlp->num_used++] = obj;
 924     return false;
 925 }
 926
 927 /*
 928  * Hash function for symbol table lookup.  Don't even think about changing
 929  * this.  It is specified by the System V ABI.
 930  */
 931 unsigned long
 932 elf_hash(const char *name)
 933 {
 934     const unsigned char *p = (const unsigned char *) name;
 935     unsigned long h = 0;
 936     unsigned long g;
 937
 938     while (*p != '\0') {
 939         h = (h << 4) + *p++;
 940         if ((g = h & 0xf0000000) != 0)
 941             h ^= g >> 24;
 942         h &= ~g;
 943     }
 944     return h;
 945 }
 946
 947 /*
 948  * Find the library with the given name, and return its full pathname.
 949  * The returned string is dynamically allocated.  Generates an error
 950  * message and returns NULL if the library cannot be found.
 951  *
 952  * If the second argument is non-NULL, then it refers to an already-
 953  * loaded shared object, whose library search path will be searched.
 954  *
 955  * The search order is:
 956  *   LD_LIBRARY_PATH
 957  *   rpath in the referencing file
 958  *   ldconfig hints
 959  *   /usr/lib
 960  */
 961 static char *
 962 find_library(const char *name, const Obj_Entry *refobj)
 963 {
 964     char *pathname;
 965
 966     if (strchr(name, '/') != NULL) {    /* Hard coded pathname */
 967         if (name[0] != '/' && !trust) {
 968             _rtld_error("Absolute pathname required for shared object \"%s\"",
 969               name);
 970             return NULL;
 971         }
 972         return xstrdup(name);
 973     }
 974
 975     dbg(" Searching for \"%s\"", name);
 976
 977     if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
 978       (refobj != NULL &&
 979       (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
 980       (pathname = search_library_path(name, gethints())) != NULL ||
 981       (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
 982         return pathname;
 983
 984     if(refobj != NULL && refobj->path != NULL) {
 985         _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
 986           name, basename(refobj->path));
 987     } else {
 988         _rtld_error("Shared object \"%s\" not found", name);
 989     }
 990     return NULL;
 991 }
 992
 993 /*
 994  * Given a symbol number in a referencing object, find the corresponding
 995  * definition of the symbol.  Returns a pointer to the symbol, or NULL if
 996  * no definition was found.  Returns a pointer to the Obj_Entry of the
 997  * defining object via the reference parameter DEFOBJ_OUT.
 998  */
 999 const Elf_Sym *
1000 find_symdef(unsigned long symnum, const Obj_Entry *refobj,
1001     const Obj_Entry **defobj_out, bool in_plt, SymCache *cache)
1002 {
1003     const Elf_Sym *ref;
1004     const Elf_Sym *def;
1005     const Obj_Entry *defobj;
1006     const char *name;
1007     unsigned long hash;
1008
1009     /*
1010      * If we have already found this symbol, get the information from
1011      * the cache.
1012      */
1013     if (symnum >= refobj->nchains)
1014         return NULL;    /* Bad object */
1015     if (cache != NULL && cache[symnum].sym != NULL) {
1016         *defobj_out = cache[symnum].obj;
1017         return cache[symnum].sym;
1018     }
1019
1020     ref = refobj->symtab + symnum;
1021     name = refobj->strtab + ref->st_name;
1022     defobj = NULL;
1023
1024     /*
1025      * We don't have to do a full scale lookup if the symbol is local.
1026      * We know it will bind to the instance in this load module; to
1027      * which we already have a pointer (ie ref). By not doing a lookup,
1028      * we not only improve performance, but it also avoids unresolvable
1029      * symbols when local symbols are not in the hash table.
1030      *
1031      * This might occur for TLS module relocations, which simply use
1032      * symbol 0.
1033      */
1034     if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) {
1035         if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) {
1036             _rtld_error("%s: Bogus symbol table entry %lu", refobj->path,
1037                 symnum);
1038         }
1039         hash = elf_hash(name);
1040         def = symlook_default(name, hash, refobj, &defobj, in_plt);
1041     } else {
1042         def = ref;
1043         defobj = refobj;
1044     }
1045
1046     /*
1047      * If we found no definition and the reference is weak, treat the
1048      * symbol as having the value zero.
1049      */
1050     if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
1051         def = &sym_zero;
1052         defobj = obj_main;
1053     }
1054
1055     if (def != NULL) {
1056         *defobj_out = defobj;
1057         /* Record the information in the cache to avoid subsequent lookups. */
1058         if (cache != NULL) {
1059             cache[symnum].sym = def;
1060             cache[symnum].obj = defobj;
1061         }
1062     } else
1063         _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
1064     return def;
1065 }
1066
1067 /*
1068  * Return the search path from the ldconfig hints file, reading it if
1069  * necessary.  Returns NULL if there are problems with the hints file,
1070  * or if the search path there is empty.
1071  */
1072 static const char *
1073 gethints(void)
1074 {
1075     static char *hints;
1076
1077     if (hints == NULL) {
1078         int fd;
1079         struct elfhints_hdr hdr;
1080         char *p;
1081
1082         /* Keep from trying again in case the hints file is bad. */
1083         hints = "";
1084
1085         if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1)
1086             return NULL;
1087         if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
1088           hdr.magic != ELFHINTS_MAGIC ||
1089           hdr.version != 1) {
1090             close(fd);
1091             return NULL;
1092         }
1093         p = xmalloc(hdr.dirlistlen + 1);
1094         if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
1095           read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) {
1096             free(p);
1097             close(fd);
1098             return NULL;
1099         }
1100         hints = p;
1101         close(fd);
1102     }
1103     return hints[0] != '\0' ? hints : NULL;
1104 }
1105
1106 static void
1107 init_dag(Obj_Entry *root)
1108 {
1109     DoneList donelist;
1110
1111     donelist_init(&donelist);
1112     init_dag1(root, root, &donelist);
1113 }
1114
1115 static void
1116 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp)
1117 {
1118     const Needed_Entry *needed;
1119
1120     if (donelist_check(dlp, obj))
1121         return;
1122     objlist_push_tail(&obj->dldags, root);
1123     objlist_push_tail(&root->dagmembers, obj);
1124     for (needed = obj->needed;  needed != NULL;  needed = needed->next)
1125         if (needed->obj != NULL)
1126             init_dag1(root, needed->obj, dlp);
1127 }
1128
1129 /*
1130  * Initialize the dynamic linker.  The argument is the address at which
1131  * the dynamic linker has been mapped into memory.  The primary task of
1132  * this function is to relocate the dynamic linker.
1133  */
1134 static void
1135 init_rtld(caddr_t mapbase)
1136 {
1137     Obj_Entry objtmp;   /* Temporary rtld object */
1138
1139     /*
1140      * Conjure up an Obj_Entry structure for the dynamic linker.
1141      *
1142      * The "path" member can't be initialized yet because string constatns
1143      * cannot yet be acessed. Below we will set it correctly.
1144      */
1145     objtmp.path = NULL;
1146     objtmp.rtld = true;
1147     objtmp.mapbase = mapbase;
1148 #ifdef PIC
1149     objtmp.relocbase = mapbase;
1150 #endif
1151     if (&_DYNAMIC != 0) {
1152         objtmp.dynamic = rtld_dynamic(&objtmp);
1153         digest_dynamic(&objtmp, 1);
1154         assert(objtmp.needed == NULL);
1155         assert(!objtmp.textrel);
1156
1157         /*
1158          * Temporarily put the dynamic linker entry into the object list, so
1159          * that symbols can be found.
1160          */
1161
1162         relocate_objects(&objtmp, true, &objtmp);
1163     }
1164
1165     /* Initialize the object list. */
1166     obj_tail = &obj_list;
1167
1168     /* Now that non-local variables can be accesses, copy out obj_rtld. */
1169     memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld));
1170
1171     /* Replace the path with a dynamically allocated copy. */
1172     obj_rtld.path = xstrdup(PATH_RTLD);
1173
1174     r_debug.r_brk = r_debug_state;
1175     r_debug.r_state = RT_CONSISTENT;
1176 }
1177
1178 /*
1179  * Add the init functions from a needed object list (and its recursive
1180  * needed objects) to "list".  This is not used directly; it is a helper
1181  * function for initlist_add_objects().  The write lock must be held
1182  * when this function is called.
1183  */
1184 static void
1185 initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1186 {
1187     /* Recursively process the successor needed objects. */
1188     if (needed->next != NULL)
1189         initlist_add_neededs(needed->next, list);
1190
1191     /* Process the current needed object. */
1192     if (needed->obj != NULL)
1193         initlist_add_objects(needed->obj, &needed->obj->next, list);
1194 }
1195
1196 /*
1197  * Scan all of the DAGs rooted in the range of objects from "obj" to
1198  * "tail" and add their init functions to "list".  This recurses over
1199  * the DAGs and ensure the proper init ordering such that each object's
1200  * needed libraries are initialized before the object itself.  At the
1201  * same time, this function adds the objects to the global finalization
1202  * list "list_fini" in the opposite order.  The write lock must be
1203  * held when this function is called.
1204  */
1205 static void
1206 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1207 {
1208     if (obj->init_done)
1209         return;
1210     obj->init_done = true;
1211
1212     /* Recursively process the successor objects. */
1213     if (&obj->next != tail)
1214         initlist_add_objects(obj->next, tail, list);
1215
1216     /* Recursively process the needed objects. */
1217     if (obj->needed != NULL)
1218         initlist_add_neededs(obj->needed, list);
1219
1220     /* Add the object to the init list. */
1221     if (obj->init != NULL)
1222         objlist_push_tail(list, obj);
1223
1224     /* Add the object to the global fini list in the reverse order. */
1225     if (obj->fini != NULL)
1226         objlist_push_head(&list_fini, obj);
1227 }
1228
1229 static bool
1230 is_exported(const Elf_Sym *def)
1231 {
1232     func_ptr_type value;
1233     const func_ptr_type *p;
1234
1235     value = (func_ptr_type)(obj_rtld.relocbase + def->st_value);
1236     for (p = exports;  *p != NULL;  p++)
1237         if (*p == value)
1238             return true;
1239     return false;
1240 }
1241
1242 /*
1243  * Given a shared object, traverse its list of needed objects, and load
1244  * each of them.  Returns 0 on success.  Generates an error message and
1245  * returns -1 on failure.
1246  */
1247 static int
1248 load_needed_objects(Obj_Entry *first)
1249 {
1250     Obj_Entry *obj;
1251
1252     for (obj = first;  obj != NULL;  obj = obj->next) {
1253         Needed_Entry *needed;
1254
1255         for (needed = obj->needed;  needed != NULL;  needed = needed->next) {
1256             const char *name = obj->strtab + needed->name;
1257             char *path = find_library(name, obj);
1258
1259             needed->obj = NULL;
1260             if (path == NULL && !ld_tracing)
1261                 return -1;
1262
1263             if (path) {
1264                 needed->obj = load_object(path);
1265                 if (needed->obj == NULL && !ld_tracing)
1266                     return -1;          /* XXX - cleanup */
1267             }
1268         }
1269     }
1270
1271     return 0;
1272 }
1273
1274 #define RTLD_FUNCTRACE "_rtld_functrace"
1275
1276 static int
1277 load_preload_objects(void)
1278 {
1279     char *p = ld_preload;
1280     static const char delim[] = " \t:;";
1281
1282     if (p == NULL)
1283         return 0;
1284
1285     p += strspn(p, delim);
1286     while (*p != '\0') {
1287         size_t len = strcspn(p, delim);
1288         char *path;
1289         char savech;
1290         Obj_Entry *obj;
1291         const Elf_Sym *sym;
1292
1293         savech = p[len];
1294         p[len] = '\0';
1295         if ((path = find_library(p, NULL)) == NULL)
1296             return -1;
1297         obj = load_object(path);
1298         if (obj == NULL)
1299             return -1;  /* XXX - cleanup */
1300         p[len] = savech;
1301         p += len;
1302         p += strspn(p, delim);
1303
1304         /* Check for the magic tracing function */
1305         sym = symlook_obj(RTLD_FUNCTRACE, elf_hash(RTLD_FUNCTRACE), obj, true);
1306         if (sym != NULL) {
1307                 rtld_functrace = (void *)(obj->relocbase + sym->st_value);
1308                 rtld_functrace_obj = obj;
1309         }
1310     }
1311     return 0;
1312 }
1313
1314 /*
1315  * Returns a pointer to the Obj_Entry for the object with the given path.
1316  * Returns NULL if no matching object was found.
1317  */
1318 static Obj_Entry *
1319 find_object(const char *path)
1320 {
1321     Obj_Entry *obj;
1322
1323     for (obj = obj_list->next;  obj != NULL;  obj = obj->next) {
1324         if (strcmp(obj->path, path) == 0)
1325             return(obj);
1326     }
1327     return(NULL);
1328 }
1329
1330 /*
1331  * Returns a pointer to the Obj_Entry for the object matching device and
1332  * inode of the given path. If no matching object was found, the descriptor
1333  * is returned in fd.
1334  * Returns with obj == NULL && fd == -1 on error.
1335  */
1336 static Obj_Entry *
1337 find_object2(const char *path, int *fd, struct stat *sb)
1338 {
1339     Obj_Entry *obj;
1340
1341     if ((*fd = open(path, O_RDONLY)) == -1) {
1342         _rtld_error("Cannot open \"%s\"", path);
1343         return(NULL);
1344     }
1345
1346     if (fstat(*fd, sb) == -1) {
1347         _rtld_error("Cannot fstat \"%s\"", path);
1348         close(*fd);
1349         *fd = -1;
1350         return NULL;
1351     }
1352
1353     for (obj = obj_list->next;  obj != NULL;  obj = obj->next) {
1354         if (obj->ino == sb->st_ino && obj->dev == sb->st_dev) {
1355             close(*fd);
1356             break;
1357         }
1358     }
1359
1360     return(obj);
1361 }
1362
1363 /*
1364  * Load a shared object into memory, if it is not already loaded.  The
1365  * argument must be a string allocated on the heap.  This function assumes
1366  * responsibility for freeing it when necessary.
1367  *
1368  * Returns a pointer to the Obj_Entry for the object.  Returns NULL
1369  * on failure.
1370  */
1371 static Obj_Entry *
1372 load_object(char *path)
1373 {
1374     Obj_Entry *obj;
1375     int fd = -1;
1376     struct stat sb;
1377
1378     obj = find_object(path);
1379     if (obj != NULL) {
1380         obj->refcount++;
1381         free(path);
1382         return(obj);
1383     }
1384
1385     obj = find_object2(path, &fd, &sb);
1386     if (obj != NULL) {
1387         obj->refcount++;
1388         free(path);
1389         return(obj);
1390     } else if (fd == -1) {
1391         free(path);
1392         return(NULL);
1393     }
1394
1395     dbg("loading \"%s\"", path);
1396     obj = map_object(fd, path, &sb);
1397     close(fd);
1398     if (obj == NULL) {
1399         free(path);
1400         return NULL;
1401     }
1402
1403     obj->path = path;
1404     digest_dynamic(obj, 0);
1405
1406     *obj_tail = obj;
1407     obj_tail = &obj->next;
1408     obj_count++;
1409     linkmap_add(obj);   /* for GDB & dlinfo() */
1410
1411     dbg("  %p .. %p: %s", obj->mapbase, obj->mapbase + obj->mapsize - 1,
1412         obj->path);
1413     if (obj->textrel)
1414         dbg("  WARNING: %s has impure text", obj->path);
1415
1416     obj->refcount++;
1417     return obj;
1418 }
1419
1420 /*
1421  * Check for locking violations and die if one is found.
1422  */
1423 static void
1424 lock_check(void)
1425 {
1426     int rcount, wcount;
1427
1428     rcount = lockinfo.rcount;
1429     wcount = lockinfo.wcount;
1430     assert(rcount >= 0);
1431     assert(wcount >= 0);
1432     if (wcount > 1 || (wcount != 0 && rcount != 0)) {
1433         _rtld_error("Application locking error: %d readers and %d writers"
1434           " in dynamic linker.  See DLLOCKINIT(3) in manual pages.",
1435           rcount, wcount);
1436         die();
1437     }
1438 }
1439
1440 static Obj_Entry *
1441 obj_from_addr(const void *addr)
1442 {
1443     Obj_Entry *obj;
1444
1445     for (obj = obj_list;  obj != NULL;  obj = obj->next) {
1446         if (addr < (void *) obj->mapbase)
1447             continue;
1448         if (addr < (void *) (obj->mapbase + obj->mapsize))
1449             return obj;
1450     }
1451     return NULL;
1452 }
1453
1454 /*
1455  * Call the finalization functions for each of the objects in "list"
1456  * which are unreferenced.  All of the objects are expected to have
1457  * non-NULL fini functions.
1458  */
1459 static void
1460 objlist_call_fini(Objlist *list)
1461 {
1462     Objlist_Entry *elm;
1463     char *saved_msg;
1464
1465     /*
1466      * Preserve the current error message since a fini function might
1467      * call into the dynamic linker and overwrite it.
1468      */
1469     saved_msg = errmsg_save();
1470     STAILQ_FOREACH(elm, list, link) {
1471         if (elm->obj->refcount == 0) {
1472             dbg("calling fini function for %s", elm->obj->path);
1473             (*elm->obj->fini)();
1474         }
1475     }
1476     errmsg_restore(saved_msg);
1477 }
1478
1479 /*
1480  * Call the initialization functions for each of the objects in
1481  * "list".  All of the objects are expected to have non-NULL init
1482  * functions.
1483  */
1484 static void
1485 objlist_call_init(Objlist *list)
1486 {
1487     Objlist_Entry *elm;
1488     char *saved_msg;
1489
1490     /*
1491      * Preserve the current error message since an init function might
1492      * call into the dynamic linker and overwrite it.
1493      */
1494     saved_msg = errmsg_save();
1495     STAILQ_FOREACH(elm, list, link) {
1496         dbg("calling init function for %s", elm->obj->path);
1497         (*elm->obj->init)();
1498     }
1499     errmsg_restore(saved_msg);
1500 }
1501
1502 static void
1503 objlist_clear(Objlist *list)
1504 {
1505     Objlist_Entry *elm;
1506
1507     while (!STAILQ_EMPTY(list)) {
1508         elm = STAILQ_FIRST(list);
1509         STAILQ_REMOVE_HEAD(list, link);
1510         free(elm);
1511     }
1512 }
1513
1514 static Objlist_Entry *
1515 objlist_find(Objlist *list, const Obj_Entry *obj)
1516 {
1517     Objlist_Entry *elm;
1518
1519     STAILQ_FOREACH(elm, list, link)
1520         if (elm->obj == obj)
1521             return elm;
1522     return NULL;
1523 }
1524
1525 static void
1526 objlist_init(Objlist *list)
1527 {
1528     STAILQ_INIT(list);
1529 }
1530
1531 static void
1532 objlist_push_head(Objlist *list, Obj_Entry *obj)
1533 {
1534     Objlist_Entry *elm;
1535
1536     elm = NEW(Objlist_Entry);
1537     elm->obj = obj;
1538     STAILQ_INSERT_HEAD(list, elm, link);
1539 }
1540
1541 static void
1542 objlist_push_tail(Objlist *list, Obj_Entry *obj)
1543 {
1544     Objlist_Entry *elm;
1545
1546     elm = NEW(Objlist_Entry);
1547     elm->obj = obj;
1548     STAILQ_INSERT_TAIL(list, elm, link);
1549 }
1550
1551 static void
1552 objlist_remove(Objlist *list, Obj_Entry *obj)
1553 {
1554     Objlist_Entry *elm;
1555
1556     if ((elm = objlist_find(list, obj)) != NULL) {
1557         STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
1558         free(elm);
1559     }
1560 }
1561
1562 /*
1563  * Remove all of the unreferenced objects from "list".
1564  */
1565 static void
1566 objlist_remove_unref(Objlist *list)
1567 {
1568     Objlist newlist;
1569     Objlist_Entry *elm;
1570
1571     STAILQ_INIT(&newlist);
1572     while (!STAILQ_EMPTY(list)) {
1573         elm = STAILQ_FIRST(list);
1574         STAILQ_REMOVE_HEAD(list, link);
1575         if (elm->obj->refcount == 0)
1576             free(elm);
1577         else
1578             STAILQ_INSERT_TAIL(&newlist, elm, link);
1579     }
1580     *list = newlist;
1581 }
1582
1583 /*
1584  * Relocate newly-loaded shared objects.  The argument is a pointer to
1585  * the Obj_Entry for the first such object.  All objects from the first
1586  * to the end of the list of objects are relocated.  Returns 0 on success,
1587  * or -1 on failure.
1588  */
1589 static int
1590 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj)
1591 {
1592     Obj_Entry *obj;
1593
1594     for (obj = first;  obj != NULL;  obj = obj->next) {
1595         if (obj != rtldobj)
1596             dbg("relocating \"%s\"", obj->path);
1597         if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL ||
1598             obj->symtab == NULL || obj->strtab == NULL) {
1599             _rtld_error("%s: Shared object has no run-time symbol table",
1600               obj->path);
1601             return -1;
1602         }
1603
1604         if (obj->textrel) {
1605             /* There are relocations to the write-protected text segment. */
1606             if (mprotect(obj->mapbase, obj->textsize,
1607               PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
1608                 _rtld_error("%s: Cannot write-enable text segment: %s",
1609                   obj->path, strerror(errno));
1610                 return -1;
1611             }
1612         }
1613
1614         /* Process the non-PLT relocations. */
1615         if (reloc_non_plt(obj, rtldobj))
1616                 return -1;
1617
1618         /*
1619          * Reprotect the text segment.  Make sure it is included in the
1620          * core dump since we modified it.  This unfortunately causes the
1621          * entire text segment to core-out but we don't have much of a
1622          * choice.  We could try to only reenable core dumps on pages
1623          * in which relocations occured but that is likely most of the text
1624          * pages anyway, and even that would not work because the rest of
1625          * the text pages would wind up as a read-only OBJT_DEFAULT object
1626          * (created due to our modifications) backed by the original OBJT_VNODE
1627          * object, and the ELF coredump code is currently only able to dump
1628          * vnode records for pure vnode-backed mappings, not vnode backings
1629          * to memory objects.
1630          */
1631         if (obj->textrel) {
1632             madvise(obj->mapbase, obj->textsize, MADV_CORE);
1633             if (mprotect(obj->mapbase, obj->textsize,
1634               PROT_READ|PROT_EXEC) == -1) {
1635                 _rtld_error("%s: Cannot write-protect text segment: %s",
1636                   obj->path, strerror(errno));
1637                 return -1;
1638             }
1639         }
1640
1641         /* Process the PLT relocations. */
1642         if (reloc_plt(obj) == -1)
1643             return -1;
1644         /* Relocate the jump slots if we are doing immediate binding. */
1645         if (obj->bind_now || bind_now)
1646             if (reloc_jmpslots(obj) == -1)
1647                 return -1;
1648
1649
1650         /*
1651          * Set up the magic number and version in the Obj_Entry.  These
1652          * were checked in the crt1.o from the original ElfKit, so we
1653          * set them for backward compatibility.
1654          */
1655         obj->magic = RTLD_MAGIC;
1656         obj->version = RTLD_VERSION;
1657
1658         /* Set the special PLT or GOT entries. */
1659         init_pltgot(obj);
1660     }
1661
1662     return 0;
1663 }
1664
1665 /*
1666  * Cleanup procedure.  It will be called (by the atexit mechanism) just
1667  * before the process exits.
1668  */
1669 static void
1670 rtld_exit(void)
1671 {
1672     Obj_Entry *obj;
1673
1674     dbg("rtld_exit()");
1675     /* Clear all the reference counts so the fini functions will be called. */
1676     for (obj = obj_list;  obj != NULL;  obj = obj->next)
1677         obj->refcount = 0;
1678     objlist_call_fini(&list_fini);
1679     /* No need to remove the items from the list, since we are exiting. */
1680 }
1681
1682 static void *
1683 path_enumerate(const char *path, path_enum_proc callback, void *arg)
1684 {
1685     if (path == NULL)
1686         return (NULL);
1687
1688     path += strspn(path, ":;");
1689     while (*path != '\0') {
1690         size_t len;
1691         char  *res;
1692
1693         len = strcspn(path, ":;");
1694         res = callback(path, len, arg);
1695
1696         if (res != NULL)
1697             return (res);
1698
1699         path += len;
1700         path += strspn(path, ":;");
1701     }
1702
1703     return (NULL);
1704 }
1705
1706 struct try_library_args {
1707     const char  *name;
1708     size_t       namelen;
1709     char        *buffer;
1710     size_t       buflen;
1711 };
1712
1713 static void *
1714 try_library_path(const char *dir, size_t dirlen, void *param)
1715 {
1716     struct try_library_args *arg;
1717
1718     arg = param;
1719     if (*dir == '/' || trust) {
1720         char *pathname;
1721
1722         if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
1723                 return (NULL);
1724
1725         pathname = arg->buffer;
1726         strncpy(pathname, dir, dirlen);
1727         pathname[dirlen] = '/';
1728         strcpy(pathname + dirlen + 1, arg->name);
1729
1730         dbg("  Trying \"%s\"", pathname);
1731         if (access(pathname, F_OK) == 0) {              /* We found it */
1732             pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
1733             strcpy(pathname, arg->buffer);
1734             return (pathname);
1735         }
1736     }
1737     return (NULL);
1738 }
1739
1740 static char *
1741 search_library_path(const char *name, const char *path)
1742 {
1743     char *p;
1744     struct try_library_args arg;
1745
1746     if (path == NULL)
1747         return NULL;
1748
1749     arg.name = name;
1750     arg.namelen = strlen(name);
1751     arg.buffer = xmalloc(PATH_MAX);
1752     arg.buflen = PATH_MAX;
1753
1754     p = path_enumerate(path, try_library_path, &arg);
1755
1756     free(arg.buffer);
1757
1758     return (p);
1759 }
1760
1761 int
1762 dlclose(void *handle)
1763 {
1764     Obj_Entry *root;
1765
1766     wlock_acquire();
1767     root = dlcheck(handle);
1768     if (root == NULL) {
1769         wlock_release();
1770         return -1;
1771     }
1772
1773     /* Unreference the object and its dependencies. */
1774     root->dl_refcount--;
1775     unref_dag(root);
1776
1777     if (root->refcount == 0) {
1778         /*
1779          * The object is no longer referenced, so we must unload it.
1780          * First, call the fini functions with no locks held.
1781          */
1782         wlock_release();
1783         objlist_call_fini(&list_fini);
1784         wlock_acquire();
1785         objlist_remove_unref(&list_fini);
1786
1787         /* Finish cleaning up the newly-unreferenced objects. */
1788         GDB_STATE(RT_DELETE,&root->linkmap);
1789         unload_object(root);
1790         GDB_STATE(RT_CONSISTENT,NULL);
1791     }
1792     wlock_release();
1793     return 0;
1794 }
1795
1796 const char *
1797 dlerror(void)
1798 {
1799     char *msg = error_message;
1800     error_message = NULL;
1801     return msg;
1802 }
1803
1804 void *
1805 dlopen(const char *name, int mode)
1806 {
1807     Obj_Entry **old_obj_tail;
1808     Obj_Entry *obj;
1809     Objlist initlist;
1810     int result;
1811
1812     ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
1813     if (ld_tracing != NULL)
1814         environ = (char **)*get_program_var_addr("environ");
1815
1816     objlist_init(&initlist);
1817
1818     wlock_acquire();
1819     GDB_STATE(RT_ADD,NULL);
1820
1821     old_obj_tail = obj_tail;
1822     obj = NULL;
1823     if (name == NULL) {
1824         obj = obj_main;
1825         obj->refcount++;
1826     } else {
1827         char *path = find_library(name, obj_main);
1828         if (path != NULL)
1829             obj = load_object(path);
1830     }
1831
1832     if (obj) {
1833         obj->dl_refcount++;
1834         if ((mode & RTLD_GLOBAL) && objlist_find(&list_global, obj) == NULL)
1835             objlist_push_tail(&list_global, obj);
1836         mode &= RTLD_MODEMASK;
1837         if (*old_obj_tail != NULL) {            /* We loaded something new. */
1838             assert(*old_obj_tail == obj);
1839
1840             result = load_needed_objects(obj);
1841             if (result != -1 && ld_tracing)
1842                 goto trace;
1843
1844             if (result == -1 ||
1845               (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW,
1846                &obj_rtld)) == -1) {
1847                 obj->dl_refcount--;
1848                 unref_dag(obj);
1849                 if (obj->refcount == 0)
1850                     unload_object(obj);
1851                 obj = NULL;
1852             } else {
1853                 /* Make list of init functions to call. */
1854                 initlist_add_objects(obj, &obj->next, &initlist);
1855             }
1856         } else if (ld_tracing)
1857             goto trace;
1858     }
1859
1860     GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
1861
1862     /* Call the init functions with no locks held. */
1863     wlock_release();
1864     objlist_call_init(&initlist);
1865     wlock_acquire();
1866     objlist_clear(&initlist);
1867     wlock_release();
1868     return obj;
1869 trace:
1870     trace_loaded_objects(obj);
1871     wlock_release();
1872     exit(0);
1873 }
1874
1875 void *
1876 dlsym(void *handle, const char *name)
1877 {
1878     const Obj_Entry *obj;
1879     unsigned long hash;
1880     const Elf_Sym *def;
1881     const Obj_Entry *defobj;
1882
1883     hash = elf_hash(name);
1884     def = NULL;
1885     defobj = NULL;
1886
1887     rlock_acquire();
1888     if (handle == NULL || handle == RTLD_NEXT ||
1889         handle == RTLD_DEFAULT || handle == RTLD_SELF) {
1890         void *retaddr;
1891
1892         retaddr = __builtin_return_address(0);  /* __GNUC__ only */
1893         if ((obj = obj_from_addr(retaddr)) == NULL) {
1894             _rtld_error("Cannot determine caller's shared object");
1895             rlock_release();
1896             return NULL;
1897         }
1898         if (handle == NULL) {   /* Just the caller's shared object. */
1899             def = symlook_obj(name, hash, obj, true);
1900             defobj = obj;
1901         } else if (handle == RTLD_NEXT || /* Objects after caller's */
1902                    handle == RTLD_SELF) { /* ... caller included */
1903             if (handle == RTLD_NEXT)
1904                 obj = obj->next;
1905             for (; obj != NULL; obj = obj->next) {
1906                 if ((def = symlook_obj(name, hash, obj, true)) != NULL) {
1907                     defobj = obj;
1908                     break;
1909                 }
1910             }
1911         } else {
1912             assert(handle == RTLD_DEFAULT);
1913             def = symlook_default(name, hash, obj, &defobj, true);
1914         }
1915     } else {
1916         DoneList donelist;
1917
1918         if ((obj = dlcheck(handle)) == NULL) {
1919             rlock_release();
1920             return NULL;
1921         }
1922
1923         donelist_init(&donelist);
1924         if (obj->mainprog) {
1925             /* Search main program and all libraries loaded by it. */
1926             def = symlook_list(name, hash, &list_main, &defobj, true,
1927               &donelist);
1928         } else {
1929             Needed_Entry fake;
1930
1931             /* Search the given object and its needed objects. */
1932             fake.next = NULL;
1933             fake.obj = (Obj_Entry *)obj;
1934             fake.name = 0;
1935             def = symlook_needed(name, hash, &fake, &defobj, true,
1936               &donelist);
1937         }
1938     }
1939
1940     if (def != NULL) {
1941         rlock_release();
1942         return defobj->relocbase + def->st_value;
1943     }
1944
1945     _rtld_error("Undefined symbol \"%s\"", name);
1946     rlock_release();
1947     return NULL;
1948 }
1949
1950 int
1951 dladdr(const void *addr, Dl_info *info)
1952 {
1953     const Obj_Entry *obj;
1954     const Elf_Sym *def;
1955     void *symbol_addr;
1956     unsigned long symoffset;
1957
1958     rlock_acquire();
1959     obj = obj_from_addr(addr);
1960     if (obj == NULL) {
1961         _rtld_error("No shared object contains address");
1962         rlock_release();
1963         return 0;
1964     }
1965     info->dli_fname = obj->path;
1966     info->dli_fbase = obj->mapbase;
1967     info->dli_saddr = (void *)0;
1968     info->dli_sname = NULL;
1969
1970     /*
1971      * Walk the symbol list looking for the symbol whose address is
1972      * closest to the address sent in.
1973      */
1974     for (symoffset = 0; symoffset < obj->nchains; symoffset++) {
1975         def = obj->symtab + symoffset;
1976
1977         /*
1978          * For skip the symbol if st_shndx is either SHN_UNDEF or
1979          * SHN_COMMON.
1980          */
1981         if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
1982             continue;
1983
1984         /*
1985          * If the symbol is greater than the specified address, or if it
1986          * is further away from addr than the current nearest symbol,
1987          * then reject it.
1988          */
1989         symbol_addr = obj->relocbase + def->st_value;
1990         if (symbol_addr > addr || symbol_addr < info->dli_saddr)
1991             continue;
1992
1993         /* Update our idea of the nearest symbol. */
1994         info->dli_sname = obj->strtab + def->st_name;
1995         info->dli_saddr = symbol_addr;
1996
1997         /* Exact match? */
1998         if (info->dli_saddr == addr)
1999             break;
2000     }
2001     rlock_release();
2002     return 1;
2003 }
2004
2005 int
2006 dlinfo(void *handle, int request, void *p)
2007 {
2008     const Obj_Entry *obj;
2009     int error;
2010
2011     rlock_acquire();
2012
2013     if (handle == NULL || handle == RTLD_SELF) {
2014         void *retaddr;
2015
2016         retaddr = __builtin_return_address(0);  /* __GNUC__ only */
2017         if ((obj = obj_from_addr(retaddr)) == NULL)
2018             _rtld_error("Cannot determine caller's shared object");
2019     } else
2020         obj = dlcheck(handle);
2021
2022     if (obj == NULL) {
2023         rlock_release();
2024         return (-1);
2025     }
2026
2027     error = 0;
2028     switch (request) {
2029     case RTLD_DI_LINKMAP:
2030         *((struct link_map const **)p) = &obj->linkmap;
2031         break;
2032     case RTLD_DI_ORIGIN:
2033         error = rtld_dirname(obj->path, p);
2034         break;
2035
2036     case RTLD_DI_SERINFOSIZE:
2037     case RTLD_DI_SERINFO:
2038         error = do_search_info(obj, request, (struct dl_serinfo *)p);
2039         break;
2040
2041     default:
2042         _rtld_error("Invalid request %d passed to dlinfo()", request);
2043         error = -1;
2044     }
2045
2046     rlock_release();
2047
2048     return (error);
2049 }
2050
2051 struct fill_search_info_args {
2052     int          request;
2053     unsigned int flags;
2054     Dl_serinfo  *serinfo;
2055     Dl_serpath  *serpath;
2056     char        *strspace;
2057 };
2058
2059 static void *
2060 fill_search_info(const char *dir, size_t dirlen, void *param)
2061 {
2062     struct fill_search_info_args *arg;
2063
2064     arg = param;
2065
2066     if (arg->request == RTLD_DI_SERINFOSIZE) {
2067         arg->serinfo->dls_cnt ++;
2068         arg->serinfo->dls_size += dirlen + 1;
2069     } else {
2070         struct dl_serpath *s_entry;
2071
2072         s_entry = arg->serpath;
2073         s_entry->dls_name  = arg->strspace;
2074         s_entry->dls_flags = arg->flags;
2075
2076         strncpy(arg->strspace, dir, dirlen);
2077         arg->strspace[dirlen] = '\0';
2078
2079         arg->strspace += dirlen + 1;
2080         arg->serpath++;
2081     }
2082
2083     return (NULL);
2084 }
2085
2086 static int
2087 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
2088 {
2089     struct dl_serinfo _info;
2090     struct fill_search_info_args args;
2091
2092     args.request = RTLD_DI_SERINFOSIZE;
2093     args.serinfo = &_info;
2094
2095     _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
2096     _info.dls_cnt  = 0;
2097
2098     path_enumerate(ld_library_path, fill_search_info, &args);
2099     path_enumerate(obj->rpath, fill_search_info, &args);
2100     path_enumerate(gethints(), fill_search_info, &args);
2101     path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
2102
2103
2104     if (request == RTLD_DI_SERINFOSIZE) {
2105         info->dls_size = _info.dls_size;
2106         info->dls_cnt = _info.dls_cnt;
2107         return (0);
2108     }
2109
2110     if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
2111         _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
2112         return (-1);
2113     }
2114
2115     args.request  = RTLD_DI_SERINFO;
2116     args.serinfo  = info;
2117     args.serpath  = &info->dls_serpath[0];
2118     args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
2119
2120     args.flags = LA_SER_LIBPATH;
2121     if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
2122         return (-1);
2123
2124     args.flags = LA_SER_RUNPATH;
2125     if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
2126         return (-1);
2127
2128     args.flags = LA_SER_CONFIG;
2129     if (path_enumerate(gethints(), fill_search_info, &args) != NULL)
2130         return (-1);
2131
2132     args.flags = LA_SER_DEFAULT;
2133     if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
2134         return (-1);
2135     return (0);
2136 }
2137
2138 static int
2139 rtld_dirname(const char *path, char *bname)
2140 {
2141     const char *endp;
2142
2143     /* Empty or NULL string gets treated as "." */
2144     if (path == NULL || *path == '\0') {
2145         bname[0] = '.';
2146         bname[1] = '\0';
2147         return (0);
2148     }
2149
2150     /* Strip trailing slashes */
2151     endp = path + strlen(path) - 1;
2152     while (endp > path && *endp == '/')
2153         endp--;
2154
2155     /* Find the start of the dir */
2156     while (endp > path && *endp != '/')
2157         endp--;
2158
2159     /* Either the dir is "/" or there are no slashes */
2160     if (endp == path) {
2161         bname[0] = *endp == '/' ? '/' : '.';
2162         bname[1] = '\0';
2163         return (0);
2164     } else {
2165         do {
2166             endp--;
2167         } while (endp > path && *endp == '/');
2168     }
2169
2170     if (endp - path + 2 > PATH_MAX)
2171     {
2172         _rtld_error("Filename is too long: %s", path);
2173         return(-1);
2174     }
2175
2176     strncpy(bname, path, endp - path + 1);
2177     bname[endp - path + 1] = '\0';
2178     return (0);
2179 }
2180
2181 static void
2182 linkmap_add(Obj_Entry *obj)
2183 {
2184     struct link_map *l = &obj->linkmap;
2185     struct link_map *prev;
2186
2187     obj->linkmap.l_name = obj->path;
2188     obj->linkmap.l_addr = obj->mapbase;
2189     obj->linkmap.l_ld = obj->dynamic;
2190 #ifdef __mips__
2191     /* GDB needs load offset on MIPS to use the symbols */
2192     obj->linkmap.l_offs = obj->relocbase;
2193 #endif
2194
2195     if (r_debug.r_map == NULL) {
2196         r_debug.r_map = l;
2197         return;
2198     }
2199
2200     /*
2201      * Scan to the end of the list, but not past the entry for the
2202      * dynamic linker, which we want to keep at the very end.
2203      */
2204     for (prev = r_debug.r_map;
2205       prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
2206       prev = prev->l_next)
2207         ;
2208
2209     /* Link in the new entry. */
2210     l->l_prev = prev;
2211     l->l_next = prev->l_next;
2212     if (l->l_next != NULL)
2213         l->l_next->l_prev = l;
2214     prev->l_next = l;
2215 }
2216
2217 static void
2218 linkmap_delete(Obj_Entry *obj)
2219 {
2220     struct link_map *l = &obj->linkmap;
2221
2222     if (l->l_prev == NULL) {
2223         if ((r_debug.r_map = l->l_next) != NULL)
2224             l->l_next->l_prev = NULL;
2225         return;
2226     }
2227
2228     if ((l->l_prev->l_next = l->l_next) != NULL)
2229         l->l_next->l_prev = l->l_prev;
2230 }
2231
2232 /*
2233  * Function for the debugger to set a breakpoint on to gain control.
2234  *
2235  * The two parameters allow the debugger to easily find and determine
2236  * what the runtime loader is doing and to whom it is doing it.
2237  *
2238  * When the loadhook trap is hit (r_debug_state, set at program
2239  * initialization), the arguments can be found on the stack:
2240  *
2241  *  +8   struct link_map *m
2242  *  +4   struct r_debug  *rd
2243  *  +0   RetAddr
2244  */
2245 void
2246 r_debug_state(struct r_debug* rd, struct link_map *m)
2247 {
2248 }
2249
2250 /*
2251  * Get address of the pointer variable in the main program.
2252  */
2253 static const void **
2254 get_program_var_addr(const char *name)
2255 {
2256     const Obj_Entry *obj;
2257     unsigned long hash;
2258
2259     hash = elf_hash(name);
2260     for (obj = obj_main;  obj != NULL;  obj = obj->next) {
2261         const Elf_Sym *def;
2262
2263         if ((def = symlook_obj(name, hash, obj, false)) != NULL) {
2264             const void **addr;
2265
2266             addr = (const void **)(obj->relocbase + def->st_value);
2267             return addr;
2268         }
2269     }
2270     return NULL;
2271 }
2272
2273 /*
2274  * Set a pointer variable in the main program to the given value.  This
2275  * is used to set key variables such as "environ" before any of the
2276  * init functions are called.
2277  */
2278 static void
2279 set_program_var(const char *name, const void *value)
2280 {
2281     const void **addr;
2282
2283     if ((addr = get_program_var_addr(name)) != NULL) {
2284         dbg("\"%s\": *%p <-- %p", name, addr, value);
2285         *addr = value;
2286     }
2287 }
2288
2289 /*
2290  * This is a special version of getenv which is far more efficient
2291  * at finding LD_ environment vars.
2292  */
2293 static
2294 const char *
2295 _getenv_ld(const char *id)
2296 {
2297     const char *envp;
2298     int i, j;
2299     int idlen = strlen(id);
2300
2301     if (ld_index == LD_ARY_CACHE)
2302         return(getenv(id));
2303     if (ld_index == 0) {
2304         for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) {
2305             if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_')
2306                 ld_ary[j++] = envp;
2307         }
2308         if (j == 0)
2309                 ld_ary[j++] = "";
2310         ld_index = j;
2311     }
2312     for (i = ld_index - 1; i >= 0; --i) {
2313         if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=')
2314             return(ld_ary[i] + idlen + 1);
2315     }
2316     return(NULL);
2317 }
2318
2319 /*
2320  * Given a symbol name in a referencing object, find the corresponding
2321  * definition of the symbol.  Returns a pointer to the symbol, or NULL if
2322  * no definition was found.  Returns a pointer to the Obj_Entry of the
2323  * defining object via the reference parameter DEFOBJ_OUT.
2324  */
2325 static const Elf_Sym *
2326 symlook_default(const char *name, unsigned long hash,
2327     const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt)
2328 {
2329     DoneList donelist;
2330     const Elf_Sym *def;
2331     const Elf_Sym *symp;
2332     const Obj_Entry *obj;
2333     const Obj_Entry *defobj;
2334     const Objlist_Entry *elm;
2335     def = NULL;
2336     defobj = NULL;
2337     donelist_init(&donelist);
2338
2339     /* Look first in the referencing object if linked symbolically. */
2340     if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
2341         symp = symlook_obj(name, hash, refobj, in_plt);
2342         if (symp != NULL) {
2343             def = symp;
2344             defobj = refobj;
2345         }
2346     }
2347
2348     /* Search all objects loaded at program start up. */
2349     if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2350         symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist);
2351         if (symp != NULL &&
2352           (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2353             def = symp;
2354             defobj = obj;
2355         }
2356     }
2357
2358     /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
2359     STAILQ_FOREACH(elm, &list_global, link) {
2360        if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2361            break;
2362        symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
2363          &donelist);
2364         if (symp != NULL &&
2365           (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2366             def = symp;
2367             defobj = obj;
2368         }
2369     }
2370
2371     /* Search all dlopened DAGs containing the referencing object. */
2372     STAILQ_FOREACH(elm, &refobj->dldags, link) {
2373         if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2374             break;
2375         symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
2376           &donelist);
2377         if (symp != NULL &&
2378           (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2379             def = symp;
2380             defobj = obj;
2381         }
2382     }
2383
2384     /*
2385      * Search the dynamic linker itself, and possibly resolve the
2386      * symbol from there.  This is how the application links to
2387      * dynamic linker services such as dlopen.  Only the values listed
2388      * in the "exports" array can be resolved from the dynamic linker.
2389      */
2390     if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2391         symp = symlook_obj(name, hash, &obj_rtld, in_plt);
2392         if (symp != NULL && is_exported(symp)) {
2393             def = symp;
2394             defobj = &obj_rtld;
2395         }
2396     }
2397
2398     if (def != NULL)
2399         *defobj_out = defobj;
2400     return def;
2401 }
2402
2403 static const Elf_Sym *
2404 symlook_list(const char *name, unsigned long hash, const Objlist *objlist,
2405   const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp)
2406 {
2407     const Elf_Sym *symp;
2408     const Elf_Sym *def;
2409     const Obj_Entry *defobj;
2410     const Objlist_Entry *elm;
2411
2412     def = NULL;
2413     defobj = NULL;
2414     STAILQ_FOREACH(elm, objlist, link) {
2415         if (donelist_check(dlp, elm->obj))
2416             continue;
2417         if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) {
2418             if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) {
2419                 def = symp;
2420                 defobj = elm->obj;
2421                 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2422                     break;
2423             }
2424         }
2425     }
2426     if (def != NULL)
2427         *defobj_out = defobj;
2428     return def;
2429 }
2430
2431 /*
2432  * Search the symbol table of a shared object and all objects needed
2433  * by it for a symbol of the given name.  Search order is
2434  * breadth-first.  Returns a pointer to the symbol, or NULL if no
2435  * definition was found.
2436  */
2437 static const Elf_Sym *
2438 symlook_needed(const char *name, unsigned long hash, const Needed_Entry *needed,
2439   const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp)
2440 {
2441     const Elf_Sym *def, *def_w;
2442     const Needed_Entry *n;
2443     const Obj_Entry *obj, *defobj, *defobj1;
2444
2445     def = def_w = NULL;
2446     defobj = NULL;
2447     for (n = needed; n != NULL; n = n->next) {
2448         if ((obj = n->obj) == NULL ||
2449             donelist_check(dlp, obj) ||
2450             (def = symlook_obj(name, hash, obj, in_plt)) == NULL)
2451                 continue;
2452         defobj = obj;
2453         if (ELF_ST_BIND(def->st_info) != STB_WEAK) {
2454             *defobj_out = defobj;
2455             return (def);
2456         }
2457     }
2458     /*
2459      * There we come when either symbol definition is not found in
2460      * directly needed objects, or found symbol is weak.
2461      */
2462     for (n = needed; n != NULL; n = n->next) {
2463         if ((obj = n->obj) == NULL)
2464             continue;
2465         def_w = symlook_needed(name, hash, obj->needed, &defobj1,
2466                                in_plt, dlp);
2467         if (def_w == NULL)
2468             continue;
2469         if (def == NULL || ELF_ST_BIND(def_w->st_info) != STB_WEAK) {
2470             def = def_w;
2471             defobj = defobj1;
2472         }
2473         if (ELF_ST_BIND(def_w->st_info) != STB_WEAK)
2474             break;
2475     }
2476     if (def != NULL)
2477         *defobj_out = defobj;
2478     return def;
2479 }
2480
2481 /*
2482  * Search the symbol table of a single shared object for a symbol of
2483  * the given name.  Returns a pointer to the symbol, or NULL if no
2484  * definition was found.
2485  *
2486  * The symbol's hash value is passed in for efficiency reasons; that
2487  * eliminates many recomputations of the hash value.
2488  */
2489 const Elf_Sym *
2490 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj,
2491   bool in_plt)
2492 {
2493     if (obj->buckets != NULL) {
2494         unsigned long symnum = obj->buckets[hash % obj->nbuckets];
2495
2496         while (symnum != STN_UNDEF) {
2497             const Elf_Sym *symp;
2498             const char *strp;
2499
2500             if (symnum >= obj->nchains)
2501                 return NULL;    /* Bad object */
2502             symp = obj->symtab + symnum;
2503             strp = obj->strtab + symp->st_name;
2504
2505             if (name[0] == strp[0] && strcmp(name, strp) == 0)
2506                 return symp->st_shndx != SHN_UNDEF ||
2507                   (!in_plt && symp->st_value != 0 &&
2508                   ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL;
2509
2510             symnum = obj->chains[symnum];
2511         }
2512     }
2513     return NULL;
2514 }
2515
2516 static void
2517 trace_loaded_objects(Obj_Entry *obj)
2518 {
2519     const char *fmt1, *fmt2, *fmt, *main_local;
2520     int         c;
2521
2522     if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
2523         main_local = "";
2524
2525     if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
2526         fmt1 = "\t%o => %p (%x)\n";
2527
2528     if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
2529         fmt2 = "\t%o (%x)\n";
2530
2531     for (; obj; obj = obj->next) {
2532         Needed_Entry            *needed;
2533         char                    *name, *path;
2534         bool                    is_lib;
2535
2536         for (needed = obj->needed; needed; needed = needed->next) {
2537             if (needed->obj != NULL) {
2538                 if (needed->obj->traced)
2539                     continue;
2540                 needed->obj->traced = true;
2541                 path = needed->obj->path;
2542             } else
2543                 path = "not found";
2544
2545             name = (char *)obj->strtab + needed->name;
2546             is_lib = strncmp(name, "lib", 3) == 0;      /* XXX - bogus */
2547
2548             fmt = is_lib ? fmt1 : fmt2;
2549             while ((c = *fmt++) != '\0') {
2550                 switch (c) {
2551                 default:
2552                     putchar(c);
2553                     continue;
2554                 case '\\':
2555                     switch (c = *fmt) {
2556                     case '\0':
2557                         continue;
2558                     case 'n':
2559                         putchar('\n');
2560                         break;
2561                     case 't':
2562                         putchar('\t');
2563                         break;
2564                     }
2565                     break;
2566                 case '%':
2567                     switch (c = *fmt) {
2568                     case '\0':
2569                         continue;
2570                     case '%':
2571                     default:
2572                         putchar(c);
2573                         break;
2574                     case 'A':
2575                         printf("%s", main_local);
2576                         break;
2577                     case 'a':
2578                         printf("%s", obj_main->path);
2579                         break;
2580                     case 'o':
2581                         printf("%s", name);
2582                         break;
2583 #if 0
2584                     case 'm':
2585                         printf("%d", sodp->sod_major);
2586                         break;
2587                     case 'n':
2588                         printf("%d", sodp->sod_minor);
2589                         break;
2590 #endif
2591                     case 'p':
2592                         printf("%s", path);
2593                         break;
2594                     case 'x':
2595                         printf("%p", needed->obj ? needed->obj->mapbase : 0);
2596                         break;
2597                     }
2598                     break;
2599                 }
2600                 ++fmt;
2601             }
2602         }
2603     }
2604 }
2605
2606 /*
2607  * Unload a dlopened object and its dependencies from memory and from
2608  * our data structures.  It is assumed that the DAG rooted in the
2609  * object has already been unreferenced, and that the object has a
2610  * reference count of 0.
2611  */
2612 static void
2613 unload_object(Obj_Entry *root)
2614 {
2615     Obj_Entry *obj;
2616     Obj_Entry **linkp;
2617
2618     assert(root->refcount == 0);
2619
2620     /*
2621      * Pass over the DAG removing unreferenced objects from
2622      * appropriate lists.
2623      */
2624     unlink_object(root);
2625
2626     /* Unmap all objects that are no longer referenced. */
2627     linkp = &obj_list->next;
2628     while ((obj = *linkp) != NULL) {
2629         if (obj->refcount == 0) {
2630             dbg("unloading \"%s\"", obj->path);
2631             munmap(obj->mapbase, obj->mapsize);
2632             linkmap_delete(obj);
2633             *linkp = obj->next;
2634             obj_count--;
2635             obj_free(obj);
2636         } else
2637             linkp = &obj->next;
2638     }
2639     obj_tail = linkp;
2640 }
2641
2642 static void
2643 unlink_object(Obj_Entry *root)
2644 {
2645     const Needed_Entry *needed;
2646     Objlist_Entry *elm;
2647
2648     if (root->refcount == 0) {
2649         /* Remove the object from the RTLD_GLOBAL list. */
2650         objlist_remove(&list_global, root);
2651
2652         /* Remove the object from all objects' DAG lists. */
2653         STAILQ_FOREACH(elm, &root->dagmembers , link)
2654             objlist_remove(&elm->obj->dldags, root);
2655     }
2656
2657     for (needed = root->needed;  needed != NULL;  needed = needed->next)
2658         if (needed->obj != NULL)
2659             unlink_object(needed->obj);
2660 }
2661
2662 static void
2663 unref_dag(Obj_Entry *root)
2664 {
2665     const Needed_Entry *needed;
2666
2667     if (root->refcount == 0)
2668         return;
2669     root->refcount--;
2670     if (root->refcount == 0)
2671         for (needed = root->needed;  needed != NULL;  needed = needed->next)
2672             if (needed->obj != NULL)
2673                 unref_dag(needed->obj);
2674 }
2675
2676 /*
2677  * Common code for MD __tls_get_addr().
2678  */
2679 void *
2680 tls_get_addr_common(void **dtvp, int index, size_t offset)
2681 {
2682     Elf_Addr* dtv = *dtvp;
2683
2684     /* Check dtv generation in case new modules have arrived */
2685     if (dtv[0] != tls_dtv_generation) {
2686         Elf_Addr* newdtv;
2687         int to_copy;
2688
2689         wlock_acquire();
2690
2691         newdtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr));
2692         to_copy = dtv[1];
2693         if (to_copy > tls_max_index)
2694             to_copy = tls_max_index;
2695         memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr));
2696         newdtv[0] = tls_dtv_generation;
2697         newdtv[1] = tls_max_index;
2698         free(dtv);
2699         *dtvp = newdtv;
2700
2701         wlock_release();
2702     }
2703
2704     /* Dynamically allocate module TLS if necessary */
2705     if (!dtv[index + 1]) {
2706         /* XXX
2707          * here we should avoid to be re-entered by signal handler
2708          * code, I assume wlock_acquire will masked all signals,
2709          * otherwise there is race and dead lock thread itself.
2710          */
2711         wlock_acquire();
2712         if (!dtv[index + 1])
2713             dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
2714         wlock_release();
2715     }
2716
2717     return (void*) (dtv[index + 1] + offset);
2718 }
2719
2720 #if defined(RTLD_STATIC_TLS_VARIANT_II)
2721
2722 /*
2723  * Allocate the static TLS area.  Return a pointer to the TCB.  The
2724  * static area is based on negative offsets relative to the tcb.
2725  *
2726  * The TCB contains an errno pointer for the system call layer, but because
2727  * we are the RTLD we really have no idea how the caller was compiled so
2728  * the information has to be passed in.  errno can either be:
2729  *
2730  *      type 0  errno is a simple non-TLS global pointer.
2731  *              (special case for e.g. libc_rtld)
2732  *      type 1  errno accessed by GOT entry     (dynamically linked programs)
2733  *      type 2  errno accessed by %gs:OFFSET    (statically linked programs)
2734  */
2735 struct tls_tcb *
2736 allocate_tls(Obj_Entry *objs)
2737 {
2738     Obj_Entry *obj;
2739     size_t data_size;
2740     size_t dtv_size;
2741     struct tls_tcb *tcb;
2742     Elf_Addr *dtv;
2743     Elf_Addr addr;
2744
2745     /*
2746      * Allocate the new TCB.  static TLS storage is placed just before the
2747      * TCB to support the %gs:OFFSET (negative offset) model.
2748      */
2749     data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
2750                 ~RTLD_STATIC_TLS_ALIGN_MASK;
2751     tcb = malloc(data_size + sizeof(*tcb));
2752     tcb = (void *)((char *)tcb + data_size);    /* actual tcb location */
2753
2754     dtv_size = (tls_max_index + 2) * sizeof(Elf_Addr);
2755     dtv = malloc(dtv_size);
2756     bzero(dtv, dtv_size);
2757
2758 #ifdef RTLD_TCB_HAS_SELF_POINTER
2759     tcb->tcb_self = tcb;
2760 #endif
2761     tcb->tcb_dtv = dtv;
2762     tcb->tcb_pthread = NULL;
2763
2764     dtv[0] = tls_dtv_generation;
2765     dtv[1] = tls_max_index;
2766
2767     for (obj = objs; obj; obj = obj->next) {
2768         if (obj->tlsoffset) {
2769             addr = (Elf_Addr)tcb - obj->tlsoffset;
2770             memset((void *)(addr + obj->tlsinitsize),
2771                    0, obj->tlssize - obj->tlsinitsize);
2772             if (obj->tlsinit)
2773                 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
2774             dtv[obj->tlsindex + 1] = addr;
2775         }
2776     }
2777     return(tcb);
2778 }
2779
2780 void
2781 free_tls(struct tls_tcb *tcb)
2782 {
2783     Elf_Addr *dtv;
2784     int dtv_size, i;
2785     Elf_Addr tls_start, tls_end;
2786     size_t data_size;
2787
2788     data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
2789                 ~RTLD_STATIC_TLS_ALIGN_MASK;
2790     dtv = tcb->tcb_dtv;
2791     dtv_size = dtv[1];
2792     tls_end = (Elf_Addr)tcb;
2793     tls_start = (Elf_Addr)tcb - data_size;
2794     for (i = 0; i < dtv_size; i++) {
2795         if (dtv[i+2] != 0 && (dtv[i+2] < tls_start || dtv[i+2] > tls_end)) {
2796             free((void *)dtv[i+2]);
2797         }
2798     }
2799     free((void *)tls_start);
2800 }
2801
2802 #else
2803 #error "Unsupported TLS layout"
2804 #endif
2805
2806 /*
2807  * Allocate TLS block for module with given index.
2808  */
2809 void *
2810 allocate_module_tls(int index)
2811 {
2812     Obj_Entry* obj;
2813     char* p;
2814
2815     for (obj = obj_list; obj; obj = obj->next) {
2816         if (obj->tlsindex == index)
2817             break;
2818     }
2819     if (!obj) {
2820         _rtld_error("Can't find module with TLS index %d", index);
2821         die();
2822     }
2823
2824     p = malloc(obj->tlssize);
2825     memcpy(p, obj->tlsinit, obj->tlsinitsize);
2826     memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
2827
2828     return p;
2829 }
2830
2831 bool
2832 allocate_tls_offset(Obj_Entry *obj)
2833 {
2834     size_t off;
2835
2836     if (obj->tls_done)
2837         return true;
2838
2839     if (obj->tlssize == 0) {
2840         obj->tls_done = true;
2841         return true;
2842     }
2843
2844     if (obj->tlsindex == 1)
2845         off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign);
2846     else
2847         off = calculate_tls_offset(tls_last_offset, tls_last_size,
2848                                    obj->tlssize, obj->tlsalign);
2849
2850     /*
2851      * If we have already fixed the size of the static TLS block, we
2852      * must stay within that size. When allocating the static TLS, we
2853      * leave a small amount of space spare to be used for dynamically
2854      * loading modules which use static TLS.
2855      */
2856     if (tls_static_space) {
2857         if (calculate_tls_end(off, obj->tlssize) > tls_static_space)
2858             return false;
2859     }
2860
2861     tls_last_offset = obj->tlsoffset = off;
2862     tls_last_size = obj->tlssize;
2863     obj->tls_done = true;
2864
2865     return true;
2866 }
2867
2868 void
2869 free_tls_offset(Obj_Entry *obj)
2870 {
2871 #ifdef RTLD_STATIC_TLS_VARIANT_II
2872     /*
2873      * If we were the last thing to allocate out of the static TLS
2874      * block, we give our space back to the 'allocator'. This is a
2875      * simplistic workaround to allow libGL.so.1 to be loaded and
2876      * unloaded multiple times. We only handle the Variant II
2877      * mechanism for now - this really needs a proper allocator.
2878      */
2879     if (calculate_tls_end(obj->tlsoffset, obj->tlssize)
2880         == calculate_tls_end(tls_last_offset, tls_last_size)) {
2881         tls_last_offset -= obj->tlssize;
2882         tls_last_size = 0;
2883     }
2884 #endif
2885 }
2886
2887 struct tls_tcb *
2888 _rtld_allocate_tls(void)
2889 {
2890     struct tls_tcb *new_tcb;
2891
2892     wlock_acquire();
2893     new_tcb = allocate_tls(obj_list);
2894     wlock_release();
2895
2896     return (new_tcb);
2897 }
2898
2899 void
2900 _rtld_free_tls(struct tls_tcb *tcb)
2901 {
2902     wlock_acquire();
2903     free_tls(tcb);
2904     wlock_release();
2905 }
2906