1 /*- 2 * Copyright 1996-1998 John D. Polstra. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 * 25 * $Id: rtld.c,v 1.20 1999/04/09 00:28:31 jdp Exp $ 26 */ 27 28 /* 29 * Dynamic linker for ELF. 30 * 31 * John Polstra <jdp@polstra.com>. 32 */ 33 34 #ifndef __GNUC__ 35 #error "GCC is needed to compile this file" 36 #endif 37 38 #include <sys/param.h> 39 #include <sys/mman.h> 40 41 #include <dlfcn.h> 42 #include <err.h> 43 #include <errno.h> 44 #include <fcntl.h> 45 #include <stdarg.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include <string.h> 49 #include <unistd.h> 50 51 #include "debug.h" 52 #include "rtld.h" 53 54 /* 55 * Version number queried by dlversion(). The first 3 digits represent 56 * the base FreeBSD release. The last 3 digits are a serial number. 57 * Increase this when you fix a significant bug or add a significant 58 * feature. 59 */ 60 #define DL_VERSION 400001 61 62 /* 63 * Debugging support. 64 */ 65 66 #define assert(cond) ((cond) ? (void) 0 :\ 67 (msg("oops: " __XSTRING(__LINE__) "\n"), abort())) 68 #define msg(s) (write(1, s, strlen(s))) 69 #define trace() msg("trace: " __XSTRING(__LINE__) "\n"); 70 71 #define END_SYM "end" 72 73 /* Types. */ 74 typedef void (*func_ptr_type)(); 75 76 /* 77 * Function declarations. 78 */ 79 static void call_fini_functions(Obj_Entry *); 80 static void call_init_functions(Obj_Entry *); 81 static void die(void); 82 static void digest_dynamic(Obj_Entry *); 83 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t); 84 static Obj_Entry *dlcheck(void *); 85 static char *find_library(const char *, const Obj_Entry *); 86 static const char *gethints(void); 87 static void init_rtld(caddr_t); 88 static bool is_exported(const Elf_Sym *); 89 static void linkmap_add(Obj_Entry *); 90 static void linkmap_delete(Obj_Entry *); 91 static int load_needed_objects(Obj_Entry *); 92 static int load_preload_objects(void); 93 static Obj_Entry *load_object(char *); 94 static Obj_Entry *obj_from_addr(const void *); 95 static int relocate_objects(Obj_Entry *, bool); 96 static void rtld_exit(void); 97 static char *search_library_path(const char *, const char *); 98 static void unref_object_dag(Obj_Entry *); 99 static void trace_loaded_objects(Obj_Entry *obj); 100 101 void r_debug_state(void); 102 void xprintf(const char *, ...); 103 104 #ifdef DEBUG 105 static const char *basename(const char *); 106 #endif 107 108 /* 109 * Data declarations. 110 */ 111 static char *error_message; /* Message for dlerror(), or NULL */ 112 struct r_debug r_debug; /* for GDB; */ 113 static bool trust; /* False for setuid and setgid programs */ 114 static char *ld_bind_now; /* Environment variable for immediate binding */ 115 static char *ld_debug; /* Environment variable for debugging */ 116 static char *ld_library_path; /* Environment variable for search path */ 117 static char *ld_preload; /* Environment variable for libraries to 118 load first */ 119 static char *ld_tracing; /* Called from ldd to print libs */ 120 static Obj_Entry **main_tail; /* Value of obj_tail after loading main and 121 its needed shared libraries */ 122 static Obj_Entry *obj_list; /* Head of linked list of shared objects */ 123 static Obj_Entry **obj_tail; /* Link field of last object in list */ 124 static Obj_Entry *obj_main; /* The main program shared object */ 125 static Obj_Entry obj_rtld; /* The dynamic linker shared object */ 126 127 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ 128 129 #define GDB_STATE(s) r_debug.r_state = s; r_debug_state(); 130 131 extern Elf_Dyn _DYNAMIC; 132 #pragma weak _DYNAMIC 133 134 /* 135 * These are the functions the dynamic linker exports to application 136 * programs. They are the only symbols the dynamic linker is willing 137 * to export from itself. 138 */ 139 static func_ptr_type exports[] = { 140 (func_ptr_type) &_rtld_error, 141 (func_ptr_type) &dlclose, 142 (func_ptr_type) &dlerror, 143 (func_ptr_type) &dlopen, 144 (func_ptr_type) &dlsym, 145 (func_ptr_type) &dladdr, 146 (func_ptr_type) &dlversion, 147 NULL 148 }; 149 150 /* 151 * Global declarations normally provided by crt1. The dynamic linker is 152 * not build with crt1, so we have to provide them ourselves. 153 */ 154 char *__progname; 155 char **environ; 156 157 /* 158 * Main entry point for dynamic linking. The first argument is the 159 * stack pointer. The stack is expected to be laid out as described 160 * in the SVR4 ABI specification, Intel 386 Processor Supplement. 161 * Specifically, the stack pointer points to a word containing 162 * ARGC. Following that in the stack is a null-terminated sequence 163 * of pointers to argument strings. Then comes a null-terminated 164 * sequence of pointers to environment strings. Finally, there is a 165 * sequence of "auxiliary vector" entries. 166 * 167 * The second argument points to a place to store the dynamic linker's 168 * exit procedure pointer and the third to a place to store the main 169 * program's object. 170 * 171 * The return value is the main program's entry point. 172 */ 173 func_ptr_type 174 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) 175 { 176 Elf_Auxinfo *aux_info[AT_COUNT]; 177 int i; 178 int argc; 179 char **argv; 180 char **env; 181 Elf_Auxinfo *aux; 182 Elf_Auxinfo *auxp; 183 184 /* 185 * On entry, the dynamic linker itself has not been relocated yet. 186 * Be very careful not to reference any global data until after 187 * init_rtld has returned. It is OK to reference file-scope statics 188 * and string constants, and to call static and global functions. 189 */ 190 191 /* Find the auxiliary vector on the stack. */ 192 argc = *sp++; 193 argv = (char **) sp; 194 sp += argc + 1; /* Skip over arguments and NULL terminator */ 195 env = (char **) sp; 196 while (*sp++ != 0) /* Skip over environment, and NULL terminator */ 197 ; 198 aux = (Elf_Auxinfo *) sp; 199 200 /* Digest the auxiliary vector. */ 201 for (i = 0; i < AT_COUNT; i++) 202 aux_info[i] = NULL; 203 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 204 if (auxp->a_type < AT_COUNT) 205 aux_info[auxp->a_type] = auxp; 206 } 207 208 /* Initialize and relocate ourselves. */ 209 assert(aux_info[AT_BASE] != NULL); 210 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 211 212 __progname = obj_rtld.path; 213 environ = env; 214 215 trust = geteuid() == getuid() && getegid() == getgid(); 216 217 ld_bind_now = getenv("LD_BIND_NOW"); 218 if (trust) { 219 ld_debug = getenv("LD_DEBUG"); 220 ld_library_path = getenv("LD_LIBRARY_PATH"); 221 ld_preload = getenv("LD_PRELOAD"); 222 } 223 ld_tracing = getenv("LD_TRACE_LOADED_OBJECTS"); 224 225 if (ld_debug != NULL && *ld_debug != '\0') 226 debug = 1; 227 dbg("%s is initialized, base address = %p", __progname, 228 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 229 dbg("RTLD dynamic = %p", obj_rtld.dynamic); 230 dbg("RTLD pltgot = %p", obj_rtld.pltgot); 231 232 /* 233 * Load the main program, or process its program header if it is 234 * already loaded. 235 */ 236 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ 237 int fd = aux_info[AT_EXECFD]->a_un.a_val; 238 dbg("loading main program"); 239 obj_main = map_object(fd); 240 close(fd); 241 if (obj_main == NULL) 242 die(); 243 } else { /* Main program already loaded. */ 244 const Elf_Phdr *phdr; 245 int phnum; 246 caddr_t entry; 247 248 dbg("processing main program's program header"); 249 assert(aux_info[AT_PHDR] != NULL); 250 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; 251 assert(aux_info[AT_PHNUM] != NULL); 252 phnum = aux_info[AT_PHNUM]->a_un.a_val; 253 assert(aux_info[AT_PHENT] != NULL); 254 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); 255 assert(aux_info[AT_ENTRY] != NULL); 256 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; 257 obj_main = digest_phdr(phdr, phnum, entry); 258 } 259 260 obj_main->path = xstrdup(argv[0] ? argv[0] : "(null)"); 261 obj_main->mainprog = true; 262 digest_dynamic(obj_main); 263 264 linkmap_add(obj_main); 265 linkmap_add(&obj_rtld); 266 267 /* Link the main program into the list of objects. */ 268 *obj_tail = obj_main; 269 obj_tail = &obj_main->next; 270 obj_main->refcount++; 271 272 /* Initialize a fake symbol for resolving undefined weak references. */ 273 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 274 sym_zero.st_shndx = SHN_ABS; 275 276 dbg("loading LD_PRELOAD libraries"); 277 if (load_preload_objects() == -1) 278 die(); 279 280 dbg("loading needed objects"); 281 if (load_needed_objects(obj_main) == -1) 282 die(); 283 main_tail = obj_tail; 284 285 if (ld_tracing) { /* We're done */ 286 trace_loaded_objects(obj_main); 287 exit(0); 288 } 289 290 dbg("relocating objects"); 291 if (relocate_objects(obj_main, 292 ld_bind_now != NULL && *ld_bind_now != '\0') == -1) 293 die(); 294 295 dbg("doing copy relocations"); 296 if (do_copy_relocations(obj_main) == -1) 297 die(); 298 299 dbg("calling _init functions"); 300 call_init_functions(obj_main->next); 301 302 dbg("transferring control to program entry point = %p", obj_main->entry); 303 304 r_debug_state(); /* say hello to gdb! */ 305 306 /* Return the exit procedure and the program entry point. */ 307 *exit_proc = rtld_exit; 308 *objp = obj_main; 309 return (func_ptr_type) obj_main->entry; 310 } 311 312 caddr_t 313 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 314 { 315 const Elf_Rel *rel; 316 const Elf_Sym *def; 317 const Obj_Entry *defobj; 318 Elf_Addr *where; 319 caddr_t target; 320 321 if (obj->pltrel) 322 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); 323 else 324 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); 325 326 where = (Elf_Addr *) (obj->relocbase + rel->r_offset); 327 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true); 328 if (def == NULL) 329 die(); 330 331 target = (caddr_t) (defobj->relocbase + def->st_value); 332 333 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", 334 defobj->strtab + def->st_name, basename(obj->path), 335 target, basename(defobj->path)); 336 337 *where = (Elf_Addr) target; 338 return target; 339 } 340 341 /* 342 * Error reporting function. Use it like printf. If formats the message 343 * into a buffer, and sets things up so that the next call to dlerror() 344 * will return the message. 345 */ 346 void 347 _rtld_error(const char *fmt, ...) 348 { 349 static char buf[512]; 350 va_list ap; 351 352 va_start(ap, fmt); 353 vsnprintf(buf, sizeof buf, fmt, ap); 354 error_message = buf; 355 va_end(ap); 356 } 357 358 #ifdef DEBUG 359 static const char * 360 basename(const char *name) 361 { 362 const char *p = strrchr(name, '/'); 363 return p != NULL ? p + 1 : name; 364 } 365 #endif 366 367 static void 368 call_fini_functions(Obj_Entry *first) 369 { 370 Obj_Entry *obj; 371 372 for (obj = first; obj != NULL; obj = obj->next) 373 if (obj->fini != NULL) 374 (*obj->fini)(); 375 } 376 377 static void 378 call_init_functions(Obj_Entry *first) 379 { 380 if (first != NULL) { 381 call_init_functions(first->next); 382 if (first->init != NULL) 383 (*first->init)(); 384 } 385 } 386 387 static void 388 die(void) 389 { 390 const char *msg = dlerror(); 391 392 if (msg == NULL) 393 msg = "Fatal error"; 394 errx(1, "%s", msg); 395 } 396 397 /* 398 * Process a shared object's DYNAMIC section, and save the important 399 * information in its Obj_Entry structure. 400 */ 401 static void 402 digest_dynamic(Obj_Entry *obj) 403 { 404 const Elf_Dyn *dynp; 405 Needed_Entry **needed_tail = &obj->needed; 406 const Elf_Dyn *dyn_rpath = NULL; 407 int plttype = DT_REL; 408 409 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { 410 switch (dynp->d_tag) { 411 412 case DT_REL: 413 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); 414 break; 415 416 case DT_RELSZ: 417 obj->relsize = dynp->d_un.d_val; 418 break; 419 420 case DT_RELENT: 421 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 422 break; 423 424 case DT_JMPREL: 425 obj->pltrel = (const Elf_Rel *) 426 (obj->relocbase + dynp->d_un.d_ptr); 427 break; 428 429 case DT_PLTRELSZ: 430 obj->pltrelsize = dynp->d_un.d_val; 431 break; 432 433 case DT_RELA: 434 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); 435 break; 436 437 case DT_RELASZ: 438 obj->relasize = dynp->d_un.d_val; 439 break; 440 441 case DT_RELAENT: 442 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 443 break; 444 445 case DT_PLTREL: 446 plttype = dynp->d_un.d_val; 447 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); 448 break; 449 450 case DT_SYMTAB: 451 obj->symtab = (const Elf_Sym *) 452 (obj->relocbase + dynp->d_un.d_ptr); 453 break; 454 455 case DT_SYMENT: 456 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 457 break; 458 459 case DT_STRTAB: 460 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); 461 break; 462 463 case DT_STRSZ: 464 obj->strsize = dynp->d_un.d_val; 465 break; 466 467 case DT_HASH: 468 { 469 const Elf_Addr *hashtab = (const Elf_Addr *) 470 (obj->relocbase + dynp->d_un.d_ptr); 471 obj->nbuckets = hashtab[0]; 472 obj->nchains = hashtab[1]; 473 obj->buckets = hashtab + 2; 474 obj->chains = obj->buckets + obj->nbuckets; 475 } 476 break; 477 478 case DT_NEEDED: 479 if (!obj->rtld) { 480 Needed_Entry *nep = NEW(Needed_Entry); 481 nep->name = dynp->d_un.d_val; 482 nep->obj = NULL; 483 nep->next = NULL; 484 485 *needed_tail = nep; 486 needed_tail = &nep->next; 487 } 488 break; 489 490 case DT_PLTGOT: 491 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); 492 break; 493 494 case DT_TEXTREL: 495 obj->textrel = true; 496 break; 497 498 case DT_SYMBOLIC: 499 obj->symbolic = true; 500 break; 501 502 case DT_RPATH: 503 /* 504 * We have to wait until later to process this, because we 505 * might not have gotten the address of the string table yet. 506 */ 507 dyn_rpath = dynp; 508 break; 509 510 case DT_SONAME: 511 /* Not used by the dynamic linker. */ 512 break; 513 514 case DT_INIT: 515 obj->init = (void (*)(void)) (obj->relocbase + dynp->d_un.d_ptr); 516 break; 517 518 case DT_FINI: 519 obj->fini = (void (*)(void)) (obj->relocbase + dynp->d_un.d_ptr); 520 break; 521 522 case DT_DEBUG: 523 /* XXX - not implemented yet */ 524 dbg("Filling in DT_DEBUG entry"); 525 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; 526 break; 527 528 default: 529 xprintf("Ignored d_tag %d\n",dynp->d_tag); 530 break; 531 } 532 } 533 534 obj->traced = false; 535 536 if (plttype == DT_RELA) { 537 obj->pltrela = (const Elf_Rela *) obj->pltrel; 538 obj->pltrel = NULL; 539 obj->pltrelasize = obj->pltrelsize; 540 obj->pltrelsize = 0; 541 } 542 543 if (dyn_rpath != NULL) 544 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val; 545 } 546 547 /* 548 * Process a shared object's program header. This is used only for the 549 * main program, when the kernel has already loaded the main program 550 * into memory before calling the dynamic linker. It creates and 551 * returns an Obj_Entry structure. 552 */ 553 static Obj_Entry * 554 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry) 555 { 556 Obj_Entry *obj = CNEW(Obj_Entry); 557 const Elf_Phdr *phlimit = phdr + phnum; 558 const Elf_Phdr *ph; 559 int nsegs = 0; 560 561 for (ph = phdr; ph < phlimit; ph++) { 562 switch (ph->p_type) { 563 564 case PT_PHDR: 565 assert((const Elf_Phdr *) ph->p_vaddr == phdr); 566 obj->phdr = (const Elf_Phdr *) ph->p_vaddr; 567 obj->phsize = ph->p_memsz; 568 break; 569 570 case PT_LOAD: 571 assert(nsegs < 2); 572 if (nsegs == 0) { /* First load segment */ 573 obj->vaddrbase = trunc_page(ph->p_vaddr); 574 obj->mapbase = (caddr_t) obj->vaddrbase; 575 obj->relocbase = obj->mapbase - obj->vaddrbase; 576 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - 577 obj->vaddrbase; 578 } else { /* Last load segment */ 579 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - 580 obj->vaddrbase; 581 } 582 nsegs++; 583 break; 584 585 case PT_DYNAMIC: 586 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr; 587 break; 588 } 589 } 590 assert(nsegs == 2); 591 592 obj->entry = entry; 593 return obj; 594 } 595 596 static Obj_Entry * 597 dlcheck(void *handle) 598 { 599 Obj_Entry *obj; 600 601 for (obj = obj_list; obj != NULL; obj = obj->next) 602 if (obj == (Obj_Entry *) handle) 603 break; 604 605 if (obj == NULL || obj->dl_refcount == 0) { 606 _rtld_error("Invalid shared object handle %p", handle); 607 return NULL; 608 } 609 return obj; 610 } 611 612 /* 613 * Hash function for symbol table lookup. Don't even think about changing 614 * this. It is specified by the System V ABI. 615 */ 616 unsigned long 617 elf_hash(const char *name) 618 { 619 const unsigned char *p = (const unsigned char *) name; 620 unsigned long h = 0; 621 unsigned long g; 622 623 while (*p != '\0') { 624 h = (h << 4) + *p++; 625 if ((g = h & 0xf0000000) != 0) 626 h ^= g >> 24; 627 h &= ~g; 628 } 629 return h; 630 } 631 632 /* 633 * Find the library with the given name, and return its full pathname. 634 * The returned string is dynamically allocated. Generates an error 635 * message and returns NULL if the library cannot be found. 636 * 637 * If the second argument is non-NULL, then it refers to an already- 638 * loaded shared object, whose library search path will be searched. 639 * 640 * The search order is: 641 * LD_LIBRARY_PATH 642 * ldconfig hints 643 * rpath in the referencing file 644 * /usr/lib 645 */ 646 static char * 647 find_library(const char *name, const Obj_Entry *refobj) 648 { 649 char *pathname; 650 651 if (strchr(name, '/') != NULL) { /* Hard coded pathname */ 652 if (name[0] != '/' && !trust) { 653 _rtld_error("Absolute pathname required for shared object \"%s\"", 654 name); 655 return NULL; 656 } 657 return xstrdup(name); 658 } 659 660 dbg(" Searching for \"%s\"", name); 661 662 if ((refobj != NULL && 663 (pathname = search_library_path(name, refobj->rpath)) != NULL) || 664 (pathname = search_library_path(name, ld_library_path)) != NULL || 665 (pathname = search_library_path(name, gethints())) != NULL || 666 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) 667 return pathname; 668 669 _rtld_error("Shared object \"%s\" not found", name); 670 return NULL; 671 } 672 673 /* 674 * Given a symbol number in a referencing object, find the corresponding 675 * definition of the symbol. Returns a pointer to the symbol, or NULL if 676 * no definition was found. Returns a pointer to the Obj_Entry of the 677 * defining object via the reference parameter DEFOBJ_OUT. 678 */ 679 const Elf_Sym * 680 find_symdef(unsigned long symnum, const Obj_Entry *refobj, 681 const Obj_Entry **defobj_out, bool in_plt) 682 { 683 const Elf_Sym *ref; 684 const Elf_Sym *strongdef; 685 const Elf_Sym *weakdef; 686 const Obj_Entry *obj; 687 const Obj_Entry *strongobj; 688 const Obj_Entry *weakobj; 689 const char *name; 690 unsigned long hash; 691 692 ref = refobj->symtab + symnum; 693 name = refobj->strtab + ref->st_name; 694 hash = elf_hash(name); 695 696 if (refobj->symbolic) { /* Look first in the referencing object */ 697 const Elf_Sym *def = symlook_obj(name, hash, refobj, in_plt); 698 if (def != NULL) { 699 *defobj_out = refobj; 700 return def; 701 } 702 } 703 704 /* 705 * Look in all loaded objects. Skip the referencing object, if 706 * we have already searched it. We keep track of the first weak 707 * definition and the first strong definition we encounter. If 708 * we find a strong definition we stop searching, because there 709 * won't be anything better than that. 710 */ 711 strongdef = weakdef = NULL; 712 strongobj = weakobj = NULL; 713 for (obj = obj_list; obj != NULL; obj = obj->next) { 714 if (obj != refobj || !refobj->symbolic) { 715 const Elf_Sym *def = symlook_obj(name, hash, obj, in_plt); 716 if (def != NULL) { 717 if (ELF_ST_BIND(def->st_info) == STB_WEAK) { 718 if (weakdef == NULL) { 719 weakdef = def; 720 weakobj = obj; 721 } 722 } else { 723 strongdef = def; 724 strongobj = obj; 725 break; /* We are done. */ 726 } 727 } 728 } 729 } 730 731 /* 732 * If we still don't have a strong definition, search the dynamic 733 * linker itself, and possibly resolve the symbol from there. 734 * This is how the application links to dynamic linker services 735 * such as dlopen. Only the values listed in the "exports" array 736 * can be resolved from the dynamic linker. 737 */ 738 if (strongdef == NULL) { 739 const Elf_Sym *def = symlook_obj(name, hash, &obj_rtld, in_plt); 740 if (def != NULL && is_exported(def)) { 741 if (ELF_ST_BIND(def->st_info) == STB_WEAK) { 742 if (weakdef == NULL) { 743 weakdef = def; 744 weakobj = &obj_rtld; 745 } 746 } else { 747 strongdef = def; 748 strongobj = &obj_rtld; 749 } 750 } 751 } 752 753 if (strongdef != NULL) { 754 *defobj_out = strongobj; 755 return strongdef; 756 } 757 if (weakdef != NULL) { 758 *defobj_out = weakobj; 759 return weakdef; 760 } 761 762 if (ELF_ST_BIND(ref->st_info) == STB_WEAK) { 763 *defobj_out = obj_main; 764 return &sym_zero; 765 } 766 767 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); 768 return NULL; 769 } 770 771 /* 772 * Return the search path from the ldconfig hints file, reading it if 773 * necessary. Returns NULL if there are problems with the hints file, 774 * or if the search path there is empty. 775 */ 776 static const char * 777 gethints(void) 778 { 779 static char *hints; 780 781 if (hints == NULL) { 782 int fd; 783 struct elfhints_hdr hdr; 784 char *p; 785 786 /* Keep from trying again in case the hints file is bad. */ 787 hints = ""; 788 789 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1) 790 return NULL; 791 if (read(fd, &hdr, sizeof hdr) != sizeof hdr || 792 hdr.magic != ELFHINTS_MAGIC || 793 hdr.version != 1) { 794 close(fd); 795 return NULL; 796 } 797 p = xmalloc(hdr.dirlistlen + 1); 798 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || 799 read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) { 800 free(p); 801 close(fd); 802 return NULL; 803 } 804 hints = p; 805 close(fd); 806 } 807 return hints[0] != '\0' ? hints : NULL; 808 } 809 810 /* 811 * Initialize the dynamic linker. The argument is the address at which 812 * the dynamic linker has been mapped into memory. The primary task of 813 * this function is to relocate the dynamic linker. 814 */ 815 static void 816 init_rtld(caddr_t mapbase) 817 { 818 /* 819 * Conjure up an Obj_Entry structure for the dynamic linker. 820 * 821 * The "path" member is supposed to be dynamically-allocated, but we 822 * aren't yet initialized sufficiently to do that. Below we will 823 * replace the static version with a dynamically-allocated copy. 824 */ 825 obj_rtld.path = "/usr/libexec/ld-elf.so.1"; 826 obj_rtld.rtld = true; 827 obj_rtld.mapbase = mapbase; 828 #ifdef PIC 829 obj_rtld.relocbase = mapbase; 830 #endif 831 if (&_DYNAMIC != 0) { 832 obj_rtld.dynamic = rtld_dynamic(&obj_rtld); 833 digest_dynamic(&obj_rtld); 834 assert(obj_rtld.needed == NULL); 835 assert(!obj_rtld.textrel); 836 837 /* 838 * Temporarily put the dynamic linker entry into the object list, so 839 * that symbols can be found. 840 */ 841 obj_list = &obj_rtld; 842 obj_tail = &obj_rtld.next; 843 844 relocate_objects(&obj_rtld, true); 845 } 846 847 /* Make the object list empty again. */ 848 obj_list = NULL; 849 obj_tail = &obj_list; 850 851 /* Replace the path with a dynamically allocated copy. */ 852 obj_rtld.path = xstrdup(obj_rtld.path); 853 854 r_debug.r_brk = r_debug_state; 855 r_debug.r_state = RT_CONSISTENT; 856 } 857 858 static bool 859 is_exported(const Elf_Sym *def) 860 { 861 func_ptr_type value; 862 const func_ptr_type *p; 863 864 value = (func_ptr_type)(obj_rtld.relocbase + def->st_value); 865 for (p = exports; *p != NULL; p++) 866 if (*p == value) 867 return true; 868 return false; 869 } 870 871 /* 872 * Given a shared object, traverse its list of needed objects, and load 873 * each of them. Returns 0 on success. Generates an error message and 874 * returns -1 on failure. 875 */ 876 static int 877 load_needed_objects(Obj_Entry *first) 878 { 879 Obj_Entry *obj; 880 881 for (obj = first; obj != NULL; obj = obj->next) { 882 Needed_Entry *needed; 883 884 for (needed = obj->needed; needed != NULL; needed = needed->next) { 885 const char *name = obj->strtab + needed->name; 886 char *path = find_library(name, obj); 887 888 needed->obj = NULL; 889 if (path == NULL && !ld_tracing) 890 return -1; 891 892 if (path) { 893 needed->obj = load_object(path); 894 if (needed->obj == NULL && !ld_tracing) 895 return -1; /* XXX - cleanup */ 896 } 897 } 898 } 899 900 return 0; 901 } 902 903 static int 904 load_preload_objects(void) 905 { 906 char *p = ld_preload; 907 908 if (p == NULL) 909 return NULL; 910 911 p += strspn(p, ":;"); 912 while (*p != '\0') { 913 size_t len = strcspn(p, ":;"); 914 char *path; 915 char savech; 916 917 savech = p[len]; 918 p[len] = '\0'; 919 if ((path = find_library(p, NULL)) == NULL) 920 return -1; 921 if (load_object(path) == NULL) 922 return -1; /* XXX - cleanup */ 923 p[len] = savech; 924 p += len; 925 p += strspn(p, ":;"); 926 } 927 return 0; 928 } 929 930 /* 931 * Load a shared object into memory, if it is not already loaded. The 932 * argument must be a string allocated on the heap. This function assumes 933 * responsibility for freeing it when necessary. 934 * 935 * Returns a pointer to the Obj_Entry for the object. Returns NULL 936 * on failure. 937 */ 938 static Obj_Entry * 939 load_object(char *path) 940 { 941 Obj_Entry *obj; 942 943 for (obj = obj_list->next; obj != NULL; obj = obj->next) 944 if (strcmp(obj->path, path) == 0) 945 break; 946 947 if (obj == NULL) { /* First use of this object, so we must map it in */ 948 int fd; 949 950 if ((fd = open(path, O_RDONLY)) == -1) { 951 _rtld_error("Cannot open \"%s\"", path); 952 return NULL; 953 } 954 obj = map_object(fd); 955 close(fd); 956 if (obj == NULL) { 957 free(path); 958 return NULL; 959 } 960 961 obj->path = path; 962 digest_dynamic(obj); 963 964 *obj_tail = obj; 965 obj_tail = &obj->next; 966 linkmap_add(obj); /* for GDB */ 967 968 dbg(" %p .. %p: %s", obj->mapbase, 969 obj->mapbase + obj->mapsize - 1, obj->path); 970 if (obj->textrel) 971 dbg(" WARNING: %s has impure text", obj->path); 972 } else 973 free(path); 974 975 obj->refcount++; 976 return obj; 977 } 978 979 static Obj_Entry * 980 obj_from_addr(const void *addr) 981 { 982 unsigned long endhash; 983 Obj_Entry *obj; 984 985 endhash = elf_hash(END_SYM); 986 for (obj = obj_list; obj != NULL; obj = obj->next) { 987 const Elf_Sym *endsym; 988 989 if (addr < (void *) obj->mapbase) 990 continue; 991 if ((endsym = symlook_obj(END_SYM, endhash, obj, true)) == NULL) 992 continue; /* No "end" symbol?! */ 993 if (addr < (void *) (obj->relocbase + endsym->st_value)) 994 return obj; 995 } 996 return NULL; 997 } 998 999 /* 1000 * Relocate newly-loaded shared objects. The argument is a pointer to 1001 * the Obj_Entry for the first such object. All objects from the first 1002 * to the end of the list of objects are relocated. Returns 0 on success, 1003 * or -1 on failure. 1004 */ 1005 static int 1006 relocate_objects(Obj_Entry *first, bool bind_now) 1007 { 1008 Obj_Entry *obj; 1009 1010 for (obj = first; obj != NULL; obj = obj->next) { 1011 if (obj != &obj_rtld) 1012 dbg("relocating \"%s\"", obj->path); 1013 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || 1014 obj->symtab == NULL || obj->strtab == NULL) { 1015 _rtld_error("%s: Shared object has no run-time symbol table", 1016 obj->path); 1017 return -1; 1018 } 1019 1020 if (obj->textrel) { 1021 /* There are relocations to the write-protected text segment. */ 1022 if (mprotect(obj->mapbase, obj->textsize, 1023 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { 1024 _rtld_error("%s: Cannot write-enable text segment: %s", 1025 obj->path, strerror(errno)); 1026 return -1; 1027 } 1028 } 1029 1030 /* Process the non-PLT relocations. */ 1031 if (reloc_non_plt(obj, &obj_rtld)) 1032 return -1; 1033 1034 if (obj->textrel) { /* Re-protected the text segment. */ 1035 if (mprotect(obj->mapbase, obj->textsize, 1036 PROT_READ|PROT_EXEC) == -1) { 1037 _rtld_error("%s: Cannot write-protect text segment: %s", 1038 obj->path, strerror(errno)); 1039 return -1; 1040 } 1041 } 1042 1043 /* Process the PLT relocations. */ 1044 if (reloc_plt(obj, bind_now)) 1045 return -1; 1046 1047 /* 1048 * Set up the magic number and version in the Obj_Entry. These 1049 * were checked in the crt1.o from the original ElfKit, so we 1050 * set them for backward compatibility. 1051 */ 1052 obj->magic = RTLD_MAGIC; 1053 obj->version = RTLD_VERSION; 1054 1055 /* Set the special PLT or GOT entries. */ 1056 init_pltgot(obj); 1057 } 1058 1059 return 0; 1060 } 1061 1062 /* 1063 * Cleanup procedure. It will be called (by the atexit mechanism) just 1064 * before the process exits. 1065 */ 1066 static void 1067 rtld_exit(void) 1068 { 1069 dbg("rtld_exit()"); 1070 call_fini_functions(obj_list->next); 1071 } 1072 1073 static char * 1074 search_library_path(const char *name, const char *path) 1075 { 1076 size_t namelen = strlen(name); 1077 const char *p = path; 1078 1079 if (p == NULL) 1080 return NULL; 1081 1082 p += strspn(p, ":;"); 1083 while (*p != '\0') { 1084 size_t len = strcspn(p, ":;"); 1085 1086 if (*p == '/' || trust) { 1087 char *pathname; 1088 const char *dir = p; 1089 size_t dirlen = len; 1090 1091 pathname = xmalloc(dirlen + 1 + namelen + 1); 1092 strncpy(pathname, dir, dirlen); 1093 pathname[dirlen] = '/'; 1094 strcpy(pathname + dirlen + 1, name); 1095 1096 dbg(" Trying \"%s\"", pathname); 1097 if (access(pathname, F_OK) == 0) /* We found it */ 1098 return pathname; 1099 1100 free(pathname); 1101 } 1102 p += len; 1103 p += strspn(p, ":;"); 1104 } 1105 1106 return NULL; 1107 } 1108 1109 int 1110 dlclose(void *handle) 1111 { 1112 Obj_Entry *root = dlcheck(handle); 1113 1114 if (root == NULL) 1115 return -1; 1116 1117 GDB_STATE(RT_DELETE); 1118 1119 root->dl_refcount--; 1120 unref_object_dag(root); 1121 if (root->refcount == 0) { /* We are finished with some objects. */ 1122 Obj_Entry *obj; 1123 Obj_Entry **linkp; 1124 1125 /* Finalize objects that are about to be unmapped. */ 1126 for (obj = obj_list->next; obj != NULL; obj = obj->next) 1127 if (obj->refcount == 0 && obj->fini != NULL) 1128 (*obj->fini)(); 1129 1130 /* Unmap all objects that are no longer referenced. */ 1131 linkp = &obj_list->next; 1132 while ((obj = *linkp) != NULL) { 1133 if (obj->refcount == 0) { 1134 munmap(obj->mapbase, obj->mapsize); 1135 free(obj->path); 1136 while (obj->needed != NULL) { 1137 Needed_Entry *needed = obj->needed; 1138 obj->needed = needed->next; 1139 free(needed); 1140 } 1141 linkmap_delete(obj); 1142 *linkp = obj->next; 1143 free(obj); 1144 } else 1145 linkp = &obj->next; 1146 } 1147 obj_tail = linkp; 1148 } 1149 1150 GDB_STATE(RT_CONSISTENT); 1151 1152 return 0; 1153 } 1154 1155 const char * 1156 dlerror(void) 1157 { 1158 char *msg = error_message; 1159 error_message = NULL; 1160 return msg; 1161 } 1162 1163 void * 1164 dlopen(const char *name, int mode) 1165 { 1166 Obj_Entry **old_obj_tail = obj_tail; 1167 Obj_Entry *obj = NULL; 1168 1169 GDB_STATE(RT_ADD); 1170 1171 if (name == NULL) 1172 obj = obj_main; 1173 else { 1174 char *path = find_library(name, obj_main); 1175 if (path != NULL) 1176 obj = load_object(path); 1177 } 1178 1179 if (obj) { 1180 obj->dl_refcount++; 1181 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1182 assert(*old_obj_tail == obj); 1183 1184 /* XXX - Clean up properly after an error. */ 1185 if (load_needed_objects(obj) == -1) { 1186 obj->dl_refcount--; 1187 obj = NULL; 1188 } else if (relocate_objects(obj, mode == RTLD_NOW) == -1) { 1189 obj->dl_refcount--; 1190 obj = NULL; 1191 } else 1192 call_init_functions(obj); 1193 } 1194 } 1195 1196 GDB_STATE(RT_CONSISTENT); 1197 1198 return obj; 1199 } 1200 1201 void * 1202 dlsym(void *handle, const char *name) 1203 { 1204 const Obj_Entry *obj; 1205 unsigned long hash; 1206 const Elf_Sym *def; 1207 1208 hash = elf_hash(name); 1209 def = NULL; 1210 1211 if (handle == NULL || handle == RTLD_NEXT) { 1212 void *retaddr; 1213 1214 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1215 if ((obj = obj_from_addr(retaddr)) == NULL) { 1216 _rtld_error("Cannot determine caller's shared object"); 1217 return NULL; 1218 } 1219 if (handle == NULL) /* Just the caller's shared object. */ 1220 def = symlook_obj(name, hash, obj, true); 1221 else { /* All the shared objects after the caller's */ 1222 while ((obj = obj->next) != NULL) 1223 if ((def = symlook_obj(name, hash, obj, true)) != NULL) 1224 break; 1225 } 1226 } else { 1227 if ((obj = dlcheck(handle)) == NULL) 1228 return NULL; 1229 1230 if (obj->mainprog) { 1231 /* Search main program and all libraries loaded by it. */ 1232 for ( ; obj != *main_tail; obj = obj->next) 1233 if ((def = symlook_obj(name, hash, obj, true)) != NULL) 1234 break; 1235 } else { 1236 /* 1237 * XXX - This isn't correct. The search should include the whole 1238 * DAG rooted at the given object. 1239 */ 1240 def = symlook_obj(name, hash, obj, true); 1241 } 1242 } 1243 1244 if (def != NULL) 1245 return obj->relocbase + def->st_value; 1246 1247 _rtld_error("Undefined symbol \"%s\"", name); 1248 return NULL; 1249 } 1250 1251 int 1252 dlversion(void) 1253 { 1254 return DL_VERSION; 1255 } 1256 1257 int 1258 dladdr(const void *addr, Dl_info *info) 1259 { 1260 const Obj_Entry *obj; 1261 const Elf_Sym *def; 1262 void *symbol_addr; 1263 unsigned long symoffset; 1264 1265 obj = obj_from_addr(addr); 1266 if (obj == NULL) { 1267 _rtld_error("No shared object contains address"); 1268 return 0; 1269 } 1270 info->dli_fname = obj->path; 1271 info->dli_fbase = obj->mapbase; 1272 info->dli_saddr = (void *)0; 1273 info->dli_sname = NULL; 1274 1275 /* 1276 * Walk the symbol list looking for the symbol whose address is 1277 * closest to the address sent in. 1278 */ 1279 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1280 def = obj->symtab + symoffset; 1281 1282 /* 1283 * For skip the symbol if st_shndx is either SHN_UNDEF or 1284 * SHN_COMMON. 1285 */ 1286 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1287 continue; 1288 1289 /* 1290 * If the symbol is greater than the specified address, or if it 1291 * is further away from addr than the current nearest symbol, 1292 * then reject it. 1293 */ 1294 symbol_addr = obj->relocbase + def->st_value; 1295 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1296 continue; 1297 1298 /* Update our idea of the nearest symbol. */ 1299 info->dli_sname = obj->strtab + def->st_name; 1300 info->dli_saddr = symbol_addr; 1301 1302 /* Exact match? */ 1303 if (info->dli_saddr == addr) 1304 break; 1305 } 1306 return 1; 1307 } 1308 1309 static void 1310 linkmap_add(Obj_Entry *obj) 1311 { 1312 struct link_map *l = &obj->linkmap; 1313 struct link_map *prev; 1314 1315 obj->linkmap.l_name = obj->path; 1316 obj->linkmap.l_addr = obj->mapbase; 1317 obj->linkmap.l_ld = obj->dynamic; 1318 #ifdef __mips__ 1319 /* GDB needs load offset on MIPS to use the symbols */ 1320 obj->linkmap.l_offs = obj->relocbase; 1321 #endif 1322 1323 if (r_debug.r_map == NULL) { 1324 r_debug.r_map = l; 1325 return; 1326 } 1327 1328 /* 1329 * Scan to the end of the list, but not past the entry for the 1330 * dynamic linker, which we want to keep at the very end. 1331 */ 1332 for (prev = r_debug.r_map; 1333 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; 1334 prev = prev->l_next) 1335 ; 1336 1337 /* Link in the new entry. */ 1338 l->l_prev = prev; 1339 l->l_next = prev->l_next; 1340 if (l->l_next != NULL) 1341 l->l_next->l_prev = l; 1342 prev->l_next = l; 1343 } 1344 1345 static void 1346 linkmap_delete(Obj_Entry *obj) 1347 { 1348 struct link_map *l = &obj->linkmap; 1349 1350 if (l->l_prev == NULL) { 1351 if ((r_debug.r_map = l->l_next) != NULL) 1352 l->l_next->l_prev = NULL; 1353 return; 1354 } 1355 1356 if ((l->l_prev->l_next = l->l_next) != NULL) 1357 l->l_next->l_prev = l->l_prev; 1358 } 1359 1360 /* 1361 * Function for the debugger to set a breakpoint on to gain control. 1362 */ 1363 void 1364 r_debug_state(void) 1365 { 1366 } 1367 1368 /* 1369 * Search the symbol table of a single shared object for a symbol of 1370 * the given name. Returns a pointer to the symbol, or NULL if no 1371 * definition was found. 1372 * 1373 * The symbol's hash value is passed in for efficiency reasons; that 1374 * eliminates many recomputations of the hash value. 1375 */ 1376 const Elf_Sym * 1377 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj, 1378 bool in_plt) 1379 { 1380 if (obj->buckets != NULL) { 1381 unsigned long symnum = obj->buckets[hash % obj->nbuckets]; 1382 1383 while (symnum != STN_UNDEF) { 1384 const Elf_Sym *symp; 1385 const char *strp; 1386 1387 assert(symnum < obj->nchains); 1388 symp = obj->symtab + symnum; 1389 assert(symp->st_name != 0); 1390 strp = obj->strtab + symp->st_name; 1391 1392 if (strcmp(name, strp) == 0) 1393 return symp->st_shndx != SHN_UNDEF || 1394 (!in_plt && symp->st_value != 0 && 1395 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL; 1396 1397 symnum = obj->chains[symnum]; 1398 } 1399 } 1400 return NULL; 1401 } 1402 1403 static void 1404 trace_loaded_objects(Obj_Entry *obj) 1405 { 1406 char *fmt1, *fmt2, *fmt, *main_local; 1407 int c; 1408 1409 if ((main_local = getenv("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) 1410 main_local = ""; 1411 1412 if ((fmt1 = getenv("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL) 1413 fmt1 = "\t%o => %p (%x)\n"; 1414 1415 if ((fmt2 = getenv("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL) 1416 fmt2 = "\t%o (%x)\n"; 1417 1418 for (; obj; obj = obj->next) { 1419 Needed_Entry *needed; 1420 char *name, *path; 1421 bool is_lib; 1422 1423 for (needed = obj->needed; needed; needed = needed->next) { 1424 if (needed->obj != NULL) { 1425 if (needed->obj->traced) 1426 continue; 1427 needed->obj->traced = true; 1428 path = needed->obj->path; 1429 } else 1430 path = "not found"; 1431 1432 name = (char *)obj->strtab + needed->name; 1433 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ 1434 1435 fmt = is_lib ? fmt1 : fmt2; 1436 while ((c = *fmt++) != '\0') { 1437 switch (c) { 1438 default: 1439 putchar(c); 1440 continue; 1441 case '\\': 1442 switch (c = *fmt) { 1443 case '\0': 1444 continue; 1445 case 'n': 1446 putchar('\n'); 1447 break; 1448 case 't': 1449 putchar('\t'); 1450 break; 1451 } 1452 break; 1453 case '%': 1454 switch (c = *fmt) { 1455 case '\0': 1456 continue; 1457 case '%': 1458 default: 1459 putchar(c); 1460 break; 1461 case 'A': 1462 printf("%s", main_local); 1463 break; 1464 case 'a': 1465 printf("%s", obj_main->path); 1466 break; 1467 case 'o': 1468 printf("%s", name); 1469 break; 1470 #if 0 1471 case 'm': 1472 printf("%d", sodp->sod_major); 1473 break; 1474 case 'n': 1475 printf("%d", sodp->sod_minor); 1476 break; 1477 #endif 1478 case 'p': 1479 printf("%s", path); 1480 break; 1481 case 'x': 1482 printf("%p", needed->obj ? needed->obj->mapbase : 0); 1483 break; 1484 } 1485 break; 1486 } 1487 ++fmt; 1488 } 1489 } 1490 } 1491 } 1492 1493 static void 1494 unref_object_dag(Obj_Entry *root) 1495 { 1496 assert(root->refcount != 0); 1497 root->refcount--; 1498 if (root->refcount == 0) { 1499 const Needed_Entry *needed; 1500 1501 for (needed = root->needed; needed != NULL; needed = needed->next) 1502 unref_object_dag(needed->obj); 1503 } 1504 } 1505 1506 /* 1507 * Non-mallocing printf, for use by malloc itself. 1508 * XXX - This doesn't belong in this module. 1509 */ 1510 void 1511 xprintf(const char *fmt, ...) 1512 { 1513 char buf[256]; 1514 va_list ap; 1515 1516 va_start(ap, fmt); 1517 vsprintf(buf, fmt, ap); 1518 (void)write(1, buf, strlen(buf)); 1519 va_end(ap); 1520 } 1521