ldso/dynlink.c

   1 #define _GNU_SOURCE
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4 #include <stdarg.h>
   5 #include <stddef.h>
   6 #include <string.h>
   7 #include <unistd.h>
   8 #include <stdint.h>
   9 #include <elf.h>
  10 #include <sys/mman.h>
  11 #include <limits.h>
  12 #include <fcntl.h>
  13 #include <sys/stat.h>
  14 #include <errno.h>
  15 #include <link.h>
  16 #include <setjmp.h>
  17 #include <pthread.h>
  18 #include <ctype.h>
  19 #include <dlfcn.h>
  20 #include <semaphore.h>
  21 #include "pthread_impl.h"
  22 #include "libc.h"
  23 #include "dynlink.h"
  24 #include "malloc_impl.h"
  25
  26 static void error(const char *, ...);
  27
  28 #define MAXP2(a,b) (-(-(a)&-(b)))
  29 #define ALIGN(x,y) ((x)+(y)-1 & -(y))
  30
  31 struct debug {
  32         int ver;
  33         void *head;
  34         void (*bp)(void);
  35         int state;
  36         void *base;
  37 };
  38
  39 struct td_index {
  40         size_t args[2];
  41         struct td_index *next;
  42 };
  43
  44 struct dso {
  45 #if DL_FDPIC
  46         struct fdpic_loadmap *loadmap;
  47 #else
  48         unsigned char *base;
  49 #endif
  50         char *name;
  51         size_t *dynv;
  52         struct dso *next, *prev;
  53
  54         Phdr *phdr;
  55         int phnum;
  56         size_t phentsize;
  57         Sym *syms;
  58         Elf_Symndx *hashtab;
  59         uint32_t *ghashtab;
  60         int16_t *versym;
  61         char *strings;
  62         struct dso *syms_next, *lazy_next;
  63         size_t *lazy, lazy_cnt;
  64         unsigned char *map;
  65         size_t map_len;
  66         dev_t dev;
  67         ino_t ino;
  68         char relocated;
  69         char constructed;
  70         char kernel_mapped;
  71         struct dso **deps, *needed_by;
  72         char *rpath_orig, *rpath;
  73         struct tls_module tls;
  74         size_t tls_id;
  75         size_t relro_start, relro_end;
  76         uintptr_t *new_dtv;
  77         unsigned char *new_tls;
  78         volatile int new_dtv_idx, new_tls_idx;
  79         struct td_index *td_index;
  80         struct dso *fini_next;
  81         char *shortname;
  82 #if DL_FDPIC
  83         unsigned char *base;
  84 #else
  85         struct fdpic_loadmap *loadmap;
  86 #endif
  87         struct funcdesc {
  88                 void *addr;
  89                 size_t *got;
  90         } *funcdescs;
  91         size_t *got;
  92         char buf[];
  93 };
  94
  95 struct symdef {
  96         Sym *sym;
  97         struct dso *dso;
  98 };
  99
 100 static struct builtin_tls {
 101         char c;
 102         struct pthread pt;
 103         void *space[16];
 104 } builtin_tls[1];
 105 #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
 106
 107 #define ADDEND_LIMIT 4096
 108 static size_t *saved_addends, *apply_addends_to;
 109
 110 static struct dso ldso;
 111 static struct dso *head, *tail, *fini_head, *syms_tail, *lazy_head;
 112 static char *env_path, *sys_path;
 113 static unsigned long long gencnt;
 114 static int runtime;
 115 static int ldd_mode;
 116 static int ldso_fail;
 117 static int noload;
 118 static jmp_buf *rtld_fail;
 119 static pthread_rwlock_t lock;
 120 static struct debug debug;
 121 static struct tls_module *tls_tail;
 122 static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
 123 static size_t static_tls_cnt;
 124 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
 125 static struct fdpic_loadmap *app_loadmap;
 126 static struct fdpic_dummy_loadmap app_dummy_loadmap;
 127 static struct dso *const nodeps_dummy;
 128
 129 struct debug *_dl_debug_addr = &debug;
 130
 131 extern hidden int __malloc_replaced;
 132
 133 hidden void (*const __init_array_start)(void)=0, (*const __fini_array_start)(void)=0;
 134
 135 extern hidden void (*const __init_array_end)(void), (*const __fini_array_end)(void);
 136
 137 weak_alias(__init_array_start, __init_array_end);
 138 weak_alias(__fini_array_start, __fini_array_end);
 139
 140 static int dl_strcmp(const char *l, const char *r)
 141 {
 142         for (; *l==*r && *l; l++, r++);
 143         return *(unsigned char *)l - *(unsigned char *)r;
 144 }
 145 #define strcmp(l,r) dl_strcmp(l,r)
 146
 147 /* Compute load address for a virtual address in a given dso. */
 148 #if DL_FDPIC
 149 static void *laddr(const struct dso *p, size_t v)
 150 {
 151         size_t j=0;
 152         if (!p->loadmap) return p->base + v;
 153         for (j=0; v-p->loadmap->segs[j].p_vaddr >= p->loadmap->segs[j].p_memsz; j++);
 154         return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
 155 }
 156 static void *laddr_pg(const struct dso *p, size_t v)
 157 {
 158         size_t j=0;
 159         size_t pgsz = PAGE_SIZE;
 160         if (!p->loadmap) return p->base + v;
 161         for (j=0; ; j++) {
 162                 size_t a = p->loadmap->segs[j].p_vaddr;
 163                 size_t b = a + p->loadmap->segs[j].p_memsz;
 164                 a &= -pgsz;
 165                 b += pgsz-1;
 166                 b &= -pgsz;
 167                 if (v-a<b-a) break;
 168         }
 169         return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
 170 }
 171 #define fpaddr(p, v) ((void (*)())&(struct funcdesc){ \
 172         laddr(p, v), (p)->got })
 173 #else
 174 #define laddr(p, v) (void *)((p)->base + (v))
 175 #define laddr_pg(p, v) laddr(p, v)
 176 #define fpaddr(p, v) ((void (*)())laddr(p, v))
 177 #endif
 178
 179 static void decode_vec(size_t *v, size_t *a, size_t cnt)
 180 {
 181         size_t i;
 182         for (i=0; i<cnt; i++) a[i] = 0;
 183         for (; v[0]; v+=2) if (v[0]-1<cnt-1) {
 184                 a[0] |= 1UL<<v[0];
 185                 a[v[0]] = v[1];
 186         }
 187 }
 188
 189 static int search_vec(size_t *v, size_t *r, size_t key)
 190 {
 191         for (; v[0]!=key; v+=2)
 192                 if (!v[0]) return 0;
 193         *r = v[1];
 194         return 1;
 195 }
 196
 197 static uint32_t sysv_hash(const char *s0)
 198 {
 199         const unsigned char *s = (void *)s0;
 200         uint_fast32_t h = 0;
 201         while (*s) {
 202                 h = 16*h + *s++;
 203                 h ^= h>>24 & 0xf0;
 204         }
 205         return h & 0xfffffff;
 206 }
 207
 208 static uint32_t gnu_hash(const char *s0)
 209 {
 210         const unsigned char *s = (void *)s0;
 211         uint_fast32_t h = 5381;
 212         for (; *s; s++)
 213                 h += h*32 + *s;
 214         return h;
 215 }
 216
 217 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
 218 {
 219         size_t i;
 220         Sym *syms = dso->syms;
 221         Elf_Symndx *hashtab = dso->hashtab;
 222         char *strings = dso->strings;
 223         for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
 224                 if ((!dso->versym || dso->versym[i] >= 0)
 225                     && (!strcmp(s, strings+syms[i].st_name)))
 226                         return syms+i;
 227         }
 228         return 0;
 229 }
 230
 231 static Sym *gnu_lookup(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s)
 232 {
 233         uint32_t nbuckets = hashtab[0];
 234         uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
 235         uint32_t i = buckets[h1 % nbuckets];
 236
 237         if (!i) return 0;
 238
 239         uint32_t *hashval = buckets + nbuckets + (i - hashtab[1]);
 240
 241         for (h1 |= 1; ; i++) {
 242                 uint32_t h2 = *hashval++;
 243                 if ((h1 == (h2|1)) && (!dso->versym || dso->versym[i] >= 0)
 244                     && !strcmp(s, dso->strings + dso->syms[i].st_name))
 245                         return dso->syms+i;
 246                 if (h2 & 1) break;
 247         }
 248
 249         return 0;
 250 }
 251
 252 static Sym *gnu_lookup_filtered(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s, uint32_t fofs, size_t fmask)
 253 {
 254         const size_t *bloomwords = (const void *)(hashtab+4);
 255         size_t f = bloomwords[fofs & (hashtab[2]-1)];
 256         if (!(f & fmask)) return 0;
 257
 258         f >>= (h1 >> hashtab[3]) % (8 * sizeof f);
 259         if (!(f & 1)) return 0;
 260
 261         return gnu_lookup(h1, hashtab, dso, s);
 262 }
 263
 264 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
 265 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
 266
 267 #ifndef ARCH_SYM_REJECT_UND
 268 #define ARCH_SYM_REJECT_UND(s) 0
 269 #endif
 270
 271 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
 272 {
 273         uint32_t h = 0, gh = gnu_hash(s), gho = gh / (8*sizeof(size_t)), *ght;
 274         size_t ghm = 1ul << gh % (8*sizeof(size_t));
 275         struct symdef def = {0};
 276         for (; dso; dso=dso->syms_next) {
 277                 Sym *sym;
 278                 if ((ght = dso->ghashtab)) {
 279                         sym = gnu_lookup_filtered(gh, ght, dso, s, gho, ghm);
 280                 } else {
 281                         if (!h) h = sysv_hash(s);
 282                         sym = sysv_lookup(s, h, dso);
 283                 }
 284                 if (!sym) continue;
 285                 if (!sym->st_shndx)
 286                         if (need_def || (sym->st_info&0xf) == STT_TLS
 287                             || ARCH_SYM_REJECT_UND(sym))
 288                                 continue;
 289                 if (!sym->st_value)
 290                         if ((sym->st_info&0xf) != STT_TLS)
 291                                 continue;
 292                 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
 293                 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
 294                 def.sym = sym;
 295                 def.dso = dso;
 296                 break;
 297         }
 298         return def;
 299 }
 300
 301 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
 302 {
 303         unsigned char *base = dso->base;
 304         Sym *syms = dso->syms;
 305         char *strings = dso->strings;
 306         Sym *sym;
 307         const char *name;
 308         void *ctx;
 309         int type;
 310         int sym_index;
 311         struct symdef def;
 312         size_t *reloc_addr;
 313         size_t sym_val;
 314         size_t tls_val;
 315         size_t addend;
 316         int skip_relative = 0, reuse_addends = 0, save_slot = 0;
 317
 318         if (dso == &ldso) {
 319                 /* Only ldso's REL table needs addend saving/reuse. */
 320                 if (rel == apply_addends_to)
 321                         reuse_addends = 1;
 322                 skip_relative = 1;
 323         }
 324
 325         for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
 326                 if (skip_relative && IS_RELATIVE(rel[1], dso->syms)) continue;
 327                 type = R_TYPE(rel[1]);
 328                 if (type == REL_NONE) continue;
 329                 reloc_addr = laddr(dso, rel[0]);
 330
 331                 if (stride > 2) {
 332                         addend = rel[2];
 333                 } else if (type==REL_GOT || type==REL_PLT|| type==REL_COPY) {
 334                         addend = 0;
 335                 } else if (reuse_addends) {
 336                         /* Save original addend in stage 2 where the dso
 337                          * chain consists of just ldso; otherwise read back
 338                          * saved addend since the inline one was clobbered. */
 339                         if (head==&ldso)
 340                                 saved_addends[save_slot] = *reloc_addr;
 341                         addend = saved_addends[save_slot++];
 342                 } else {
 343                         addend = *reloc_addr;
 344                 }
 345
 346                 sym_index = R_SYM(rel[1]);
 347                 if (sym_index) {
 348                         sym = syms + sym_index;
 349                         name = strings + sym->st_name;
 350                         ctx = type==REL_COPY ? head->syms_next : head;
 351                         def = (sym->st_info&0xf) == STT_SECTION
 352                                 ? (struct symdef){ .dso = dso, .sym = sym }
 353                                 : find_sym(ctx, name, type==REL_PLT);
 354                         if (!def.sym && (sym->st_shndx != SHN_UNDEF
 355                             || sym->st_info>>4 != STB_WEAK)) {
 356                                 if (dso->lazy && (type==REL_PLT || type==REL_GOT)) {
 357                                         dso->lazy[3*dso->lazy_cnt+0] = rel[0];
 358                                         dso->lazy[3*dso->lazy_cnt+1] = rel[1];
 359                                         dso->lazy[3*dso->lazy_cnt+2] = addend;
 360                                         dso->lazy_cnt++;
 361                                         continue;
 362                                 }
 363                                 error("Error relocating %s: %s: symbol not found",
 364                                         dso->name, name);
 365                                 if (runtime) longjmp(*rtld_fail, 1);
 366                                 continue;
 367                         }
 368                 } else {
 369                         sym = 0;
 370                         def.sym = 0;
 371                         def.dso = dso;
 372                 }
 373
 374                 sym_val = def.sym ? (size_t)laddr(def.dso, def.sym->st_value) : 0;
 375                 tls_val = def.sym ? def.sym->st_value : 0;
 376
 377                 if ((type == REL_TPOFF || type == REL_TPOFF_NEG)
 378                     && runtime && def.dso->tls_id > static_tls_cnt) {
 379                         error("Error relocating %s: %s: initial-exec TLS "
 380                                 "resolves to dynamic definition in %s",
 381                                 dso->name, name, def.dso->name);
 382                         longjmp(*rtld_fail, 1);
 383                 }
 384
 385                 switch(type) {
 386                 case REL_NONE:
 387                         break;
 388                 case REL_OFFSET:
 389                         addend -= (size_t)reloc_addr;
 390                 case REL_SYMBOLIC:
 391                 case REL_GOT:
 392                 case REL_PLT:
 393                         *reloc_addr = sym_val + addend;
 394                         break;
 395                 case REL_RELATIVE:
 396                         *reloc_addr = (size_t)base + addend;
 397                         break;
 398                 case REL_SYM_OR_REL:
 399                         if (sym) *reloc_addr = sym_val + addend;
 400                         else *reloc_addr = (size_t)base + addend;
 401                         break;
 402                 case REL_COPY:
 403                         memcpy(reloc_addr, (void *)sym_val, sym->st_size);
 404                         break;
 405                 case REL_OFFSET32:
 406                         *(uint32_t *)reloc_addr = sym_val + addend
 407                                 - (size_t)reloc_addr;
 408                         break;
 409                 case REL_FUNCDESC:
 410                         *reloc_addr = def.sym ? (size_t)(def.dso->funcdescs
 411                                 + (def.sym - def.dso->syms)) : 0;
 412                         break;
 413                 case REL_FUNCDESC_VAL:
 414                         if ((sym->st_info&0xf) == STT_SECTION) *reloc_addr += sym_val;
 415                         else *reloc_addr = sym_val;
 416                         reloc_addr[1] = def.sym ? (size_t)def.dso->got : 0;
 417                         break;
 418                 case REL_DTPMOD:
 419                         *reloc_addr = def.dso->tls_id;
 420                         break;
 421                 case REL_DTPOFF:
 422                         *reloc_addr = tls_val + addend - DTP_OFFSET;
 423                         break;
 424 #ifdef TLS_ABOVE_TP
 425                 case REL_TPOFF:
 426                         *reloc_addr = tls_val + def.dso->tls.offset + TPOFF_K + addend;
 427                         break;
 428 #else
 429                 case REL_TPOFF:
 430                         *reloc_addr = tls_val - def.dso->tls.offset + addend;
 431                         break;
 432                 case REL_TPOFF_NEG:
 433                         *reloc_addr = def.dso->tls.offset - tls_val + addend;
 434                         break;
 435 #endif
 436                 case REL_TLSDESC:
 437                         if (stride<3) addend = reloc_addr[1];
 438                         if (runtime && def.dso->tls_id > static_tls_cnt) {
 439                                 struct td_index *new = malloc(sizeof *new);
 440                                 if (!new) {
 441                                         error(
 442                                         "Error relocating %s: cannot allocate TLSDESC for %s",
 443                                         dso->name, sym ? name : "(local)" );
 444                                         longjmp(*rtld_fail, 1);
 445                                 }
 446                                 new->next = dso->td_index;
 447                                 dso->td_index = new;
 448                                 new->args[0] = def.dso->tls_id;
 449                                 new->args[1] = tls_val + addend - DTP_OFFSET;
 450                                 reloc_addr[0] = (size_t)__tlsdesc_dynamic;
 451                                 reloc_addr[1] = (size_t)new;
 452                         } else {
 453                                 reloc_addr[0] = (size_t)__tlsdesc_static;
 454 #ifdef TLS_ABOVE_TP
 455                                 reloc_addr[1] = tls_val + def.dso->tls.offset
 456                                         + TPOFF_K + addend;
 457 #else
 458                                 reloc_addr[1] = tls_val - def.dso->tls.offset
 459                                         + addend;
 460 #endif
 461                         }
 462 #ifdef TLSDESC_BACKWARDS
 463                         /* Some archs (32-bit ARM at least) invert the order of
 464                          * the descriptor members. Fix them up here. */
 465                         size_t tmp = reloc_addr[0];
 466                         reloc_addr[0] = reloc_addr[1];
 467                         reloc_addr[1] = tmp;
 468 #endif
 469                         break;
 470                 default:
 471                         error("Error relocating %s: unsupported relocation type %d",
 472                                 dso->name, type);
 473                         if (runtime) longjmp(*rtld_fail, 1);
 474                         continue;
 475                 }
 476         }
 477 }
 478
 479 static void redo_lazy_relocs()
 480 {
 481         struct dso *p = lazy_head, *next;
 482         lazy_head = 0;
 483         for (; p; p=next) {
 484                 next = p->lazy_next;
 485                 size_t size = p->lazy_cnt*3*sizeof(size_t);
 486                 p->lazy_cnt = 0;
 487                 do_relocs(p, p->lazy, size, 3);
 488                 if (p->lazy_cnt) {
 489                         p->lazy_next = lazy_head;
 490                         lazy_head = p;
 491                 } else {
 492                         free(p->lazy);
 493                         p->lazy = 0;
 494                         p->lazy_next = 0;
 495                 }
 496         }
 497 }
 498
 499 /* A huge hack: to make up for the wastefulness of shared libraries
 500  * needing at least a page of dirty memory even if they have no global
 501  * data, we reclaim the gaps at the beginning and end of writable maps
 502  * and "donate" them to the heap. */
 503
 504 static void reclaim(struct dso *dso, size_t start, size_t end)
 505 {
 506         if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
 507         if (end   >= dso->relro_start && end   < dso->relro_end) end = dso->relro_start;
 508         if (start >= end) return;
 509         char *base = laddr_pg(dso, start);
 510         __malloc_donate(base, base+(end-start));
 511 }
 512
 513 static void reclaim_gaps(struct dso *dso)
 514 {
 515         Phdr *ph = dso->phdr;
 516         size_t phcnt = dso->phnum;
 517
 518         for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
 519                 if (ph->p_type!=PT_LOAD) continue;
 520                 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
 521                 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
 522                 reclaim(dso, ph->p_vaddr+ph->p_memsz,
 523                         ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
 524         }
 525 }
 526
 527 static void *mmap_fixed(void *p, size_t n, int prot, int flags, int fd, off_t off)
 528 {
 529         static int no_map_fixed;
 530         char *q;
 531         if (!no_map_fixed) {
 532                 q = mmap(p, n, prot, flags|MAP_FIXED, fd, off);
 533                 if (!DL_NOMMU_SUPPORT || q != MAP_FAILED || errno != EINVAL)
 534                         return q;
 535                 no_map_fixed = 1;
 536         }
 537         /* Fallbacks for MAP_FIXED failure on NOMMU kernels. */
 538         if (flags & MAP_ANONYMOUS) {
 539                 memset(p, 0, n);
 540                 return p;
 541         }
 542         ssize_t r;
 543         if (lseek(fd, off, SEEK_SET) < 0) return MAP_FAILED;
 544         for (q=p; n; q+=r, off+=r, n-=r) {
 545                 r = read(fd, q, n);
 546                 if (r < 0 && errno != EINTR) return MAP_FAILED;
 547                 if (!r) {
 548                         memset(q, 0, n);
 549                         break;
 550                 }
 551         }
 552         return p;
 553 }
 554
 555 static void unmap_library(struct dso *dso)
 556 {
 557         if (dso->loadmap) {
 558                 size_t i;
 559                 for (i=0; i<dso->loadmap->nsegs; i++) {
 560                         if (!dso->loadmap->segs[i].p_memsz)
 561                                 continue;
 562                         munmap((void *)dso->loadmap->segs[i].addr,
 563                                 dso->loadmap->segs[i].p_memsz);
 564                 }
 565                 free(dso->loadmap);
 566         } else if (dso->map && dso->map_len) {
 567                 munmap(dso->map, dso->map_len);
 568         }
 569 }
 570
 571 static void *map_library(int fd, struct dso *dso)
 572 {
 573         Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
 574         void *allocated_buf=0;
 575         size_t phsize;
 576         size_t addr_min=SIZE_MAX, addr_max=0, map_len;
 577         size_t this_min, this_max;
 578         size_t nsegs = 0;
 579         off_t off_start;
 580         Ehdr *eh;
 581         Phdr *ph, *ph0;
 582         unsigned prot;
 583         unsigned char *map=MAP_FAILED, *base;
 584         size_t dyn=0;
 585         size_t tls_image=0;
 586         size_t i;
 587
 588         ssize_t l = read(fd, buf, sizeof buf);
 589         eh = buf;
 590         if (l<0) return 0;
 591         if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
 592                 goto noexec;
 593         phsize = eh->e_phentsize * eh->e_phnum;
 594         if (phsize > sizeof buf - sizeof *eh) {
 595                 allocated_buf = malloc(phsize);
 596                 if (!allocated_buf) return 0;
 597                 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
 598                 if (l < 0) goto error;
 599                 if (l != phsize) goto noexec;
 600                 ph = ph0 = allocated_buf;
 601         } else if (eh->e_phoff + phsize > l) {
 602                 l = pread(fd, buf+1, phsize, eh->e_phoff);
 603                 if (l < 0) goto error;
 604                 if (l != phsize) goto noexec;
 605                 ph = ph0 = (void *)(buf + 1);
 606         } else {
 607                 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
 608         }
 609         for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
 610                 if (ph->p_type == PT_DYNAMIC) {
 611                         dyn = ph->p_vaddr;
 612                 } else if (ph->p_type == PT_TLS) {
 613                         tls_image = ph->p_vaddr;
 614                         dso->tls.align = ph->p_align;
 615                         dso->tls.len = ph->p_filesz;
 616                         dso->tls.size = ph->p_memsz;
 617                 } else if (ph->p_type == PT_GNU_RELRO) {
 618                         dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
 619                         dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
 620                 } else if (ph->p_type == PT_GNU_STACK) {
 621                         if (!runtime && ph->p_memsz > __default_stacksize) {
 622                                 __default_stacksize =
 623                                         ph->p_memsz < DEFAULT_STACK_MAX ?
 624                                         ph->p_memsz : DEFAULT_STACK_MAX;
 625                         }
 626                 }
 627                 if (ph->p_type != PT_LOAD) continue;
 628                 nsegs++;
 629                 if (ph->p_vaddr < addr_min) {
 630                         addr_min = ph->p_vaddr;
 631                         off_start = ph->p_offset;
 632                         prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
 633                                 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
 634                                 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
 635                 }
 636                 if (ph->p_vaddr+ph->p_memsz > addr_max) {
 637                         addr_max = ph->p_vaddr+ph->p_memsz;
 638                 }
 639         }
 640         if (!dyn) goto noexec;
 641         if (DL_FDPIC && !(eh->e_flags & FDPIC_CONSTDISP_FLAG)) {
 642                 dso->loadmap = calloc(1, sizeof *dso->loadmap
 643                         + nsegs * sizeof *dso->loadmap->segs);
 644                 if (!dso->loadmap) goto error;
 645                 dso->loadmap->nsegs = nsegs;
 646                 for (ph=ph0, i=0; i<nsegs; ph=(void *)((char *)ph+eh->e_phentsize)) {
 647                         if (ph->p_type != PT_LOAD) continue;
 648                         prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
 649                                 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
 650                                 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
 651                         map = mmap(0, ph->p_memsz + (ph->p_vaddr & PAGE_SIZE-1),
 652                                 prot, MAP_PRIVATE,
 653                                 fd, ph->p_offset & -PAGE_SIZE);
 654                         if (map == MAP_FAILED) {
 655                                 unmap_library(dso);
 656                                 goto error;
 657                         }
 658                         dso->loadmap->segs[i].addr = (size_t)map +
 659                                 (ph->p_vaddr & PAGE_SIZE-1);
 660                         dso->loadmap->segs[i].p_vaddr = ph->p_vaddr;
 661                         dso->loadmap->segs[i].p_memsz = ph->p_memsz;
 662                         i++;
 663                         if (prot & PROT_WRITE) {
 664                                 size_t brk = (ph->p_vaddr & PAGE_SIZE-1)
 665                                         + ph->p_filesz;
 666                                 size_t pgbrk = brk + PAGE_SIZE-1 & -PAGE_SIZE;
 667                                 size_t pgend = brk + ph->p_memsz - ph->p_filesz
 668                                         + PAGE_SIZE-1 & -PAGE_SIZE;
 669                                 if (pgend > pgbrk && mmap_fixed(map+pgbrk,
 670                                         pgend-pgbrk, prot,
 671                                         MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
 672                                         -1, off_start) == MAP_FAILED)
 673                                         goto error;
 674                                 memset(map + brk, 0, pgbrk-brk);
 675                         }
 676                 }
 677                 map = (void *)dso->loadmap->segs[0].addr;
 678                 map_len = 0;
 679                 goto done_mapping;
 680         }
 681         addr_max += PAGE_SIZE-1;
 682         addr_max &= -PAGE_SIZE;
 683         addr_min &= -PAGE_SIZE;
 684         off_start &= -PAGE_SIZE;
 685         map_len = addr_max - addr_min + off_start;
 686         /* The first time, we map too much, possibly even more than
 687          * the length of the file. This is okay because we will not
 688          * use the invalid part; we just need to reserve the right
 689          * amount of virtual address space to map over later. */
 690         map = DL_NOMMU_SUPPORT
 691                 ? mmap((void *)addr_min, map_len, PROT_READ|PROT_WRITE|PROT_EXEC,
 692                         MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
 693                 : mmap((void *)addr_min, map_len, prot,
 694                         MAP_PRIVATE, fd, off_start);
 695         if (map==MAP_FAILED) goto error;
 696         dso->map = map;
 697         dso->map_len = map_len;
 698         /* If the loaded file is not relocatable and the requested address is
 699          * not available, then the load operation must fail. */
 700         if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
 701                 errno = EBUSY;
 702                 goto error;
 703         }
 704         base = map - addr_min;
 705         dso->phdr = 0;
 706         dso->phnum = 0;
 707         for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
 708                 if (ph->p_type != PT_LOAD) continue;
 709                 /* Check if the programs headers are in this load segment, and
 710                  * if so, record the address for use by dl_iterate_phdr. */
 711                 if (!dso->phdr && eh->e_phoff >= ph->p_offset
 712                     && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
 713                         dso->phdr = (void *)(base + ph->p_vaddr
 714                                 + (eh->e_phoff-ph->p_offset));
 715                         dso->phnum = eh->e_phnum;
 716                         dso->phentsize = eh->e_phentsize;
 717                 }
 718                 this_min = ph->p_vaddr & -PAGE_SIZE;
 719                 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
 720                 off_start = ph->p_offset & -PAGE_SIZE;
 721                 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
 722                         ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
 723                         ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
 724                 /* Reuse the existing mapping for the lowest-address LOAD */
 725                 if ((ph->p_vaddr & -PAGE_SIZE) != addr_min || DL_NOMMU_SUPPORT)
 726                         if (mmap_fixed(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
 727                                 goto error;
 728                 if (ph->p_memsz > ph->p_filesz && (ph->p_flags&PF_W)) {
 729                         size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
 730                         size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
 731                         memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
 732                         if (pgbrk-(size_t)base < this_max && mmap_fixed((void *)pgbrk, (size_t)base+this_max-pgbrk, prot, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) == MAP_FAILED)
 733                                 goto error;
 734                 }
 735         }
 736         for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
 737                 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
 738                         if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC)
 739                             && errno != ENOSYS)
 740                                 goto error;
 741                         break;
 742                 }
 743 done_mapping:
 744         dso->base = base;
 745         dso->dynv = laddr(dso, dyn);
 746         if (dso->tls.size) dso->tls.image = laddr(dso, tls_image);
 747         free(allocated_buf);
 748         return map;
 749 noexec:
 750         errno = ENOEXEC;
 751 error:
 752         if (map!=MAP_FAILED) unmap_library(dso);
 753         free(allocated_buf);
 754         return 0;
 755 }
 756
 757 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
 758 {
 759         size_t l;
 760         int fd;
 761         for (;;) {
 762                 s += strspn(s, ":\n");
 763                 l = strcspn(s, ":\n");
 764                 if (l-1 >= INT_MAX) return -1;
 765                 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
 766                         if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
 767                         switch (errno) {
 768                         case ENOENT:
 769                         case ENOTDIR:
 770                         case EACCES:
 771                         case ENAMETOOLONG:
 772                                 break;
 773                         default:
 774                                 /* Any negative value but -1 will inhibit
 775                                  * futher path search. */
 776                                 return -2;
 777                         }
 778                 }
 779                 s += l;
 780         }
 781 }
 782
 783 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
 784 {
 785         size_t n, l;
 786         const char *s, *t, *origin;
 787         char *d;
 788         if (p->rpath || !p->rpath_orig) return 0;
 789         if (!strchr(p->rpath_orig, '$')) {
 790                 p->rpath = p->rpath_orig;
 791                 return 0;
 792         }
 793         n = 0;
 794         s = p->rpath_orig;
 795         while ((t=strchr(s, '$'))) {
 796                 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
 797                         return 0;
 798                 s = t+1;
 799                 n++;
 800         }
 801         if (n > SSIZE_MAX/PATH_MAX) return 0;
 802
 803         if (p->kernel_mapped) {
 804                 /* $ORIGIN searches cannot be performed for the main program
 805                  * when it is suid/sgid/AT_SECURE. This is because the
 806                  * pathname is under the control of the caller of execve.
 807                  * For libraries, however, $ORIGIN can be processed safely
 808                  * since the library's pathname came from a trusted source
 809                  * (either system paths or a call to dlopen). */
 810                 if (libc.secure)
 811                         return 0;
 812                 l = readlink("/proc/self/exe", buf, buf_size);
 813                 if (l == -1) switch (errno) {
 814                 case ENOENT:
 815                 case ENOTDIR:
 816                 case EACCES:
 817                         break;
 818                 default:
 819                         return -1;
 820                 }
 821                 if (l >= buf_size)
 822                         return 0;
 823                 buf[l] = 0;
 824                 origin = buf;
 825         } else {
 826                 origin = p->name;
 827         }
 828         t = strrchr(origin, '/');
 829         if (t) {
 830                 l = t-origin;
 831         } else {
 832                 /* Normally p->name will always be an absolute or relative
 833                  * pathname containing at least one '/' character, but in the
 834                  * case where ldso was invoked as a command to execute a
 835                  * program in the working directory, app.name may not. Fix. */
 836                 origin = ".";
 837                 l = 1;
 838         }
 839         /* Disallow non-absolute origins for suid/sgid/AT_SECURE. */
 840         if (libc.secure && *origin != '/')
 841                 return 0;
 842         p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
 843         if (!p->rpath) return -1;
 844
 845         d = p->rpath;
 846         s = p->rpath_orig;
 847         while ((t=strchr(s, '$'))) {
 848                 memcpy(d, s, t-s);
 849                 d += t-s;
 850                 memcpy(d, origin, l);
 851                 d += l;
 852                 /* It was determined previously that the '$' is followed
 853                  * either by "ORIGIN" or "{ORIGIN}". */
 854                 s = t + 7 + 2*(t[1]=='{');
 855         }
 856         strcpy(d, s);
 857         return 0;
 858 }
 859
 860 static void decode_dyn(struct dso *p)
 861 {
 862         size_t dyn[DYN_CNT];
 863         decode_vec(p->dynv, dyn, DYN_CNT);
 864         p->syms = laddr(p, dyn[DT_SYMTAB]);
 865         p->strings = laddr(p, dyn[DT_STRTAB]);
 866         if (dyn[0]&(1<<DT_HASH))
 867                 p->hashtab = laddr(p, dyn[DT_HASH]);
 868         if (dyn[0]&(1<<DT_RPATH))
 869                 p->rpath_orig = p->strings + dyn[DT_RPATH];
 870         if (dyn[0]&(1<<DT_RUNPATH))
 871                 p->rpath_orig = p->strings + dyn[DT_RUNPATH];
 872         if (dyn[0]&(1<<DT_PLTGOT))
 873                 p->got = laddr(p, dyn[DT_PLTGOT]);
 874         if (search_vec(p->dynv, dyn, DT_GNU_HASH))
 875                 p->ghashtab = laddr(p, *dyn);
 876         if (search_vec(p->dynv, dyn, DT_VERSYM))
 877                 p->versym = laddr(p, *dyn);
 878 }
 879
 880 static size_t count_syms(struct dso *p)
 881 {
 882         if (p->hashtab) return p->hashtab[1];
 883
 884         size_t nsym, i;
 885         uint32_t *buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
 886         uint32_t *hashval;
 887         for (i = nsym = 0; i < p->ghashtab[0]; i++) {
 888                 if (buckets[i] > nsym)
 889                         nsym = buckets[i];
 890         }
 891         if (nsym) {
 892                 hashval = buckets + p->ghashtab[0] + (nsym - p->ghashtab[1]);
 893                 do nsym++;
 894                 while (!(*hashval++ & 1));
 895         }
 896         return nsym;
 897 }
 898
 899 static void *dl_mmap(size_t n)
 900 {
 901         void *p;
 902         int prot = PROT_READ|PROT_WRITE, flags = MAP_ANONYMOUS|MAP_PRIVATE;
 903 #ifdef SYS_mmap2
 904         p = (void *)__syscall(SYS_mmap2, 0, n, prot, flags, -1, 0);
 905 #else
 906         p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
 907 #endif
 908         return p == MAP_FAILED ? 0 : p;
 909 }
 910
 911 static void makefuncdescs(struct dso *p)
 912 {
 913         static int self_done;
 914         size_t nsym = count_syms(p);
 915         size_t i, size = nsym * sizeof(*p->funcdescs);
 916
 917         if (!self_done) {
 918                 p->funcdescs = dl_mmap(size);
 919                 self_done = 1;
 920         } else {
 921                 p->funcdescs = malloc(size);
 922         }
 923         if (!p->funcdescs) {
 924                 if (!runtime) a_crash();
 925                 error("Error allocating function descriptors for %s", p->name);
 926                 longjmp(*rtld_fail, 1);
 927         }
 928         for (i=0; i<nsym; i++) {
 929                 if ((p->syms[i].st_info&0xf)==STT_FUNC && p->syms[i].st_shndx) {
 930                         p->funcdescs[i].addr = laddr(p, p->syms[i].st_value);
 931                         p->funcdescs[i].got = p->got;
 932                 } else {
 933                         p->funcdescs[i].addr = 0;
 934                         p->funcdescs[i].got = 0;
 935                 }
 936         }
 937 }
 938
 939 static struct dso *load_library(const char *name, struct dso *needed_by)
 940 {
 941         char buf[2*NAME_MAX+2];
 942         const char *pathname;
 943         unsigned char *map;
 944         struct dso *p, temp_dso = {0};
 945         int fd;
 946         struct stat st;
 947         size_t alloc_size;
 948         int n_th = 0;
 949         int is_self = 0;
 950
 951         if (!*name) {
 952                 errno = EINVAL;
 953                 return 0;
 954         }
 955
 956         /* Catch and block attempts to reload the implementation itself */
 957         if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
 958                 static const char reserved[] =
 959                         "c.pthread.rt.m.dl.util.xnet.";
 960                 const char *rp, *next;
 961                 for (rp=reserved; *rp; rp=next) {
 962                         next = strchr(rp, '.') + 1;
 963                         if (strncmp(name+3, rp, next-rp) == 0)
 964                                 break;
 965                 }
 966                 if (*rp) {
 967                         if (ldd_mode) {
 968                                 /* Track which names have been resolved
 969                                  * and only report each one once. */
 970                                 static unsigned reported;
 971                                 unsigned mask = 1U<<(rp-reserved);
 972                                 if (!(reported & mask)) {
 973                                         reported |= mask;
 974                                         dprintf(1, "\t%s => %s (%p)\n",
 975                                                 name, ldso.name,
 976                                                 ldso.base);
 977                                 }
 978                         }
 979                         is_self = 1;
 980                 }
 981         }
 982         if (!strcmp(name, ldso.name)) is_self = 1;
 983         if (is_self) {
 984                 if (!ldso.prev) {
 985                         tail->next = &ldso;
 986                         ldso.prev = tail;
 987                         tail = &ldso;
 988                 }
 989                 return &ldso;
 990         }
 991         if (strchr(name, '/')) {
 992                 pathname = name;
 993                 fd = open(name, O_RDONLY|O_CLOEXEC);
 994         } else {
 995                 /* Search for the name to see if it's already loaded */
 996                 for (p=head->next; p; p=p->next) {
 997                         if (p->shortname && !strcmp(p->shortname, name)) {
 998                                 return p;
 999                         }
1000                 }
1001                 if (strlen(name) > NAME_MAX) return 0;
1002                 fd = -1;
1003                 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
1004                 for (p=needed_by; fd == -1 && p; p=p->needed_by) {
1005                         if (fixup_rpath(p, buf, sizeof buf) < 0)
1006                                 fd = -2; /* Inhibit further search. */
1007                         if (p->rpath)
1008                                 fd = path_open(name, p->rpath, buf, sizeof buf);
1009                 }
1010                 if (fd == -1) {
1011                         if (!sys_path) {
1012                                 char *prefix = 0;
1013                                 size_t prefix_len;
1014                                 if (ldso.name[0]=='/') {
1015                                         char *s, *t, *z;
1016                                         for (s=t=z=ldso.name; *s; s++)
1017                                                 if (*s=='/') z=t, t=s;
1018                                         prefix_len = z-ldso.name;
1019                                         if (prefix_len < PATH_MAX)
1020                                                 prefix = ldso.name;
1021                                 }
1022                                 if (!prefix) {
1023                                         prefix = "";
1024                                         prefix_len = 0;
1025                                 }
1026                                 char etc_ldso_path[prefix_len + 1
1027                                         + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
1028                                 snprintf(etc_ldso_path, sizeof etc_ldso_path,
1029                                         "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
1030                                         (int)prefix_len, prefix);
1031                                 FILE *f = fopen(etc_ldso_path, "rbe");
1032                                 if (f) {
1033                                         if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
1034                                                 free(sys_path);
1035                                                 sys_path = "";
1036                                         }
1037                                         fclose(f);
1038                                 } else if (errno != ENOENT) {
1039                                         sys_path = "";
1040                                 }
1041                         }
1042                         if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
1043                         fd = path_open(name, sys_path, buf, sizeof buf);
1044                 }
1045                 pathname = buf;
1046         }
1047         if (fd < 0) return 0;
1048         if (fstat(fd, &st) < 0) {
1049                 close(fd);
1050                 return 0;
1051         }
1052         for (p=head->next; p; p=p->next) {
1053                 if (p->dev == st.st_dev && p->ino == st.st_ino) {
1054                         /* If this library was previously loaded with a
1055                          * pathname but a search found the same inode,
1056                          * setup its shortname so it can be found by name. */
1057                         if (!p->shortname && pathname != name)
1058                                 p->shortname = strrchr(p->name, '/')+1;
1059                         close(fd);
1060                         return p;
1061                 }
1062         }
1063         map = noload ? 0 : map_library(fd, &temp_dso);
1064         close(fd);
1065         if (!map) return 0;
1066
1067         /* Avoid the danger of getting two versions of libc mapped into the
1068          * same process when an absolute pathname was used. The symbols
1069          * checked are chosen to catch both musl and glibc, and to avoid
1070          * false positives from interposition-hack libraries. */
1071         decode_dyn(&temp_dso);
1072         if (find_sym(&temp_dso, "__libc_start_main", 1).sym &&
1073             find_sym(&temp_dso, "stdin", 1).sym) {
1074                 unmap_library(&temp_dso);
1075                 return load_library("libc.so", needed_by);
1076         }
1077         /* Past this point, if we haven't reached runtime yet, ldso has
1078          * committed either to use the mapped library or to abort execution.
1079          * Unmapping is not possible, so we can safely reclaim gaps. */
1080         if (!runtime) reclaim_gaps(&temp_dso);
1081
1082         /* Allocate storage for the new DSO. When there is TLS, this
1083          * storage must include a reservation for all pre-existing
1084          * threads to obtain copies of both the new TLS, and an
1085          * extended DTV capable of storing an additional slot for
1086          * the newly-loaded DSO. */
1087         alloc_size = sizeof *p + strlen(pathname) + 1;
1088         if (runtime && temp_dso.tls.image) {
1089                 size_t per_th = temp_dso.tls.size + temp_dso.tls.align
1090                         + sizeof(void *) * (tls_cnt+3);
1091                 n_th = libc.threads_minus_1 + 1;
1092                 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
1093                 else alloc_size += n_th * per_th;
1094         }
1095         p = calloc(1, alloc_size);
1096         if (!p) {
1097                 unmap_library(&temp_dso);
1098                 return 0;
1099         }
1100         memcpy(p, &temp_dso, sizeof temp_dso);
1101         p->dev = st.st_dev;
1102         p->ino = st.st_ino;
1103         p->needed_by = needed_by;
1104         p->name = p->buf;
1105         strcpy(p->name, pathname);
1106         /* Add a shortname only if name arg was not an explicit pathname. */
1107         if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
1108         if (p->tls.image) {
1109                 p->tls_id = ++tls_cnt;
1110                 tls_align = MAXP2(tls_align, p->tls.align);
1111 #ifdef TLS_ABOVE_TP
1112                 p->tls.offset = tls_offset + ( (tls_align-1) &
1113                         -(tls_offset + (uintptr_t)p->tls.image) );
1114                 tls_offset += p->tls.size;
1115 #else
1116                 tls_offset += p->tls.size + p->tls.align - 1;
1117                 tls_offset -= (tls_offset + (uintptr_t)p->tls.image)
1118                         & (p->tls.align-1);
1119                 p->tls.offset = tls_offset;
1120 #endif
1121                 p->new_dtv = (void *)(-sizeof(size_t) &
1122                         (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
1123                 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
1124                 if (tls_tail) tls_tail->next = &p->tls;
1125                 else libc.tls_head = &p->tls;
1126                 tls_tail = &p->tls;
1127         }
1128
1129         tail->next = p;
1130         p->prev = tail;
1131         tail = p;
1132
1133         if (DL_FDPIC) makefuncdescs(p);
1134
1135         if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
1136
1137         return p;
1138 }
1139
1140 static void load_deps(struct dso *p)
1141 {
1142         size_t i, ndeps=0;
1143         struct dso ***deps = &p->deps, **tmp, *dep;
1144         for (; p; p=p->next) {
1145                 for (i=0; p->dynv[i]; i+=2) {
1146                         if (p->dynv[i] != DT_NEEDED) continue;
1147                         dep = load_library(p->strings + p->dynv[i+1], p);
1148                         if (!dep) {
1149                                 error("Error loading shared library %s: %m (needed by %s)",
1150                                         p->strings + p->dynv[i+1], p->name);
1151                                 if (runtime) longjmp(*rtld_fail, 1);
1152                                 continue;
1153                         }
1154                         if (runtime) {
1155                                 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
1156                                 if (!tmp) longjmp(*rtld_fail, 1);
1157                                 tmp[ndeps++] = dep;
1158                                 tmp[ndeps] = 0;
1159                                 *deps = tmp;
1160                         }
1161                 }
1162         }
1163         if (!*deps) *deps = (struct dso **)&nodeps_dummy;
1164 }
1165
1166 static void load_preload(char *s)
1167 {
1168         int tmp;
1169         char *z;
1170         for (z=s; *z; s=z) {
1171                 for (   ; *s && (isspace(*s) || *s==':'); s++);
1172                 for (z=s; *z && !isspace(*z) && *z!=':'; z++);
1173                 tmp = *z;
1174                 *z = 0;
1175                 load_library(s, 0);
1176                 *z = tmp;
1177         }
1178 }
1179
1180 static void add_syms(struct dso *p)
1181 {
1182         if (!p->syms_next && syms_tail != p) {
1183                 syms_tail->syms_next = p;
1184                 syms_tail = p;
1185         }
1186 }
1187
1188 static void revert_syms(struct dso *old_tail)
1189 {
1190         struct dso *p, *next;
1191         /* Chop off the tail of the list of dsos that participate in
1192          * the global symbol table, reverting them to RTLD_LOCAL. */
1193         for (p=old_tail; p; p=next) {
1194                 next = p->syms_next;
1195                 p->syms_next = 0;
1196         }
1197         syms_tail = old_tail;
1198 }
1199
1200 static void do_mips_relocs(struct dso *p, size_t *got)
1201 {
1202         size_t i, j, rel[2];
1203         unsigned char *base = p->base;
1204         i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
1205         if (p==&ldso) {
1206                 got += i;
1207         } else {
1208                 while (i--) *got++ += (size_t)base;
1209         }
1210         j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1211         i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1212         Sym *sym = p->syms + j;
1213         rel[0] = (unsigned char *)got - base;
1214         for (i-=j; i; i--, sym++, rel[0]+=sizeof(size_t)) {
1215                 rel[1] = R_INFO(sym-p->syms, R_MIPS_JUMP_SLOT);
1216                 do_relocs(p, rel, sizeof rel, 2);
1217         }
1218 }
1219
1220 static void reloc_all(struct dso *p)
1221 {
1222         size_t dyn[DYN_CNT];
1223         for (; p; p=p->next) {
1224                 if (p->relocated) continue;
1225                 decode_vec(p->dynv, dyn, DYN_CNT);
1226                 if (NEED_MIPS_GOT_RELOCS)
1227                         do_mips_relocs(p, laddr(p, dyn[DT_PLTGOT]));
1228                 do_relocs(p, laddr(p, dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
1229                         2+(dyn[DT_PLTREL]==DT_RELA));
1230                 do_relocs(p, laddr(p, dyn[DT_REL]), dyn[DT_RELSZ], 2);
1231                 do_relocs(p, laddr(p, dyn[DT_RELA]), dyn[DT_RELASZ], 3);
1232
1233                 if (head != &ldso && p->relro_start != p->relro_end &&
1234                     mprotect(laddr(p, p->relro_start), p->relro_end-p->relro_start, PROT_READ)
1235                     && errno != ENOSYS) {
1236                         error("Error relocating %s: RELRO protection failed: %m",
1237                                 p->name);
1238                         if (runtime) longjmp(*rtld_fail, 1);
1239                 }
1240
1241                 p->relocated = 1;
1242         }
1243 }
1244
1245 static void kernel_mapped_dso(struct dso *p)
1246 {
1247         size_t min_addr = -1, max_addr = 0, cnt;
1248         Phdr *ph = p->phdr;
1249         for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
1250                 if (ph->p_type == PT_DYNAMIC) {
1251                         p->dynv = laddr(p, ph->p_vaddr);
1252                 } else if (ph->p_type == PT_GNU_RELRO) {
1253                         p->relro_start = ph->p_vaddr & -PAGE_SIZE;
1254                         p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
1255                 } else if (ph->p_type == PT_GNU_STACK) {
1256                         if (!runtime && ph->p_memsz > __default_stacksize) {
1257                                 __default_stacksize =
1258                                         ph->p_memsz < DEFAULT_STACK_MAX ?
1259                                         ph->p_memsz : DEFAULT_STACK_MAX;
1260                         }
1261                 }
1262                 if (ph->p_type != PT_LOAD) continue;
1263                 if (ph->p_vaddr < min_addr)
1264                         min_addr = ph->p_vaddr;
1265                 if (ph->p_vaddr+ph->p_memsz > max_addr)
1266                         max_addr = ph->p_vaddr+ph->p_memsz;
1267         }
1268         min_addr &= -PAGE_SIZE;
1269         max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
1270         p->map = p->base + min_addr;
1271         p->map_len = max_addr - min_addr;
1272         p->kernel_mapped = 1;
1273 }
1274
1275 void __libc_exit_fini()
1276 {
1277         struct dso *p;
1278         size_t dyn[DYN_CNT];
1279         for (p=fini_head; p; p=p->fini_next) {
1280                 if (!p->constructed) continue;
1281                 decode_vec(p->dynv, dyn, DYN_CNT);
1282                 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
1283                         size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
1284                         size_t *fn = (size_t *)laddr(p, dyn[DT_FINI_ARRAY])+n;
1285                         while (n--) ((void (*)(void))*--fn)();
1286                 }
1287 #ifndef NO_LEGACY_INITFINI
1288                 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
1289                         fpaddr(p, dyn[DT_FINI])();
1290 #endif
1291         }
1292 }
1293
1294 static void do_init_fini(struct dso *p)
1295 {
1296         size_t dyn[DYN_CNT];
1297         int need_locking = libc.threads_minus_1;
1298         /* Allow recursive calls that arise when a library calls
1299          * dlopen from one of its constructors, but block any
1300          * other threads until all ctors have finished. */
1301         if (need_locking) pthread_mutex_lock(&init_fini_lock);
1302         for (; p; p=p->prev) {
1303                 if (p->constructed) continue;
1304                 p->constructed = 1;
1305                 decode_vec(p->dynv, dyn, DYN_CNT);
1306                 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
1307                         p->fini_next = fini_head;
1308                         fini_head = p;
1309                 }
1310 #ifndef NO_LEGACY_INITFINI
1311                 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
1312                         fpaddr(p, dyn[DT_INIT])();
1313 #endif
1314                 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
1315                         size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
1316                         size_t *fn = laddr(p, dyn[DT_INIT_ARRAY]);
1317                         while (n--) ((void (*)(void))*fn++)();
1318                 }
1319                 if (!need_locking && libc.threads_minus_1) {
1320                         need_locking = 1;
1321                         pthread_mutex_lock(&init_fini_lock);
1322                 }
1323         }
1324         if (need_locking) pthread_mutex_unlock(&init_fini_lock);
1325 }
1326
1327 void __libc_start_init(void)
1328 {
1329         do_init_fini(tail);
1330 }
1331
1332 static void dl_debug_state(void)
1333 {
1334 }
1335
1336 weak_alias(dl_debug_state, _dl_debug_state);
1337
1338 void __init_tls(size_t *auxv)
1339 {
1340 }
1341
1342 static void update_tls_size()
1343 {
1344         libc.tls_cnt = tls_cnt;
1345         libc.tls_align = tls_align;
1346         libc.tls_size = ALIGN(
1347                 (1+tls_cnt) * sizeof(void *) +
1348                 tls_offset +
1349                 sizeof(struct pthread) +
1350                 tls_align * 2,
1351         tls_align);
1352 }
1353
1354 void __dl_prepare_for_threads(void)
1355 {
1356         /* MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED */
1357         __syscall(SYS_membarrier, 1<<4, 0);
1358 }
1359
1360 static sem_t barrier_sem;
1361 static void bcast_barrier(int s)
1362 {
1363         sem_post(&barrier_sem);
1364 }
1365
1366 static void install_new_tls(void)
1367 {
1368         sigset_t set;
1369         pthread_t self = __pthread_self(), td;
1370         uintptr_t (*newdtv)[tls_cnt+1] = (void *)tail->new_dtv;
1371         struct dso *p;
1372         size_t i, j;
1373         size_t old_cnt = self->dtv[0];
1374
1375         __block_app_sigs(&set);
1376         __tl_lock();
1377         /* Copy existing dtv contents from all existing threads. */
1378         for (i=0, td=self; !i || td!=self; i++, td=td->next) {
1379                 memcpy(newdtv+i, td->dtv,
1380                         (old_cnt+1)*sizeof(uintptr_t));
1381                 newdtv[i][0] = tls_cnt;
1382         }
1383         /* Install new dtls into the enlarged, uninstalled dtv copies. */
1384         for (p=head; ; p=p->next) {
1385                 if (!p->tls_id || self->dtv[p->tls_id]) continue;
1386                 unsigned char *mem = p->new_tls;
1387                 for (j=0; j<i; j++) {
1388                         unsigned char *new = mem;
1389                         new += ((uintptr_t)p->tls.image - (uintptr_t)mem)
1390                                 & (p->tls.align-1);
1391                         memcpy(new, p->tls.image, p->tls.len);
1392                         newdtv[j][p->tls_id] =
1393                                 (uintptr_t)new + DTP_OFFSET;
1394                         mem += p->tls.size + p->tls.align;
1395                 }
1396                 if (p->tls_id == tls_cnt) break;
1397         }
1398
1399         /* Broadcast barrier to ensure contents of new dtv is visible
1400          * if the new dtv pointer is. Use SYS_membarrier if it works,
1401          * otherwise emulate with a signal. */
1402
1403         /* MEMBARRIER_CMD_PRIVATE_EXPEDITED */
1404         if (__syscall(SYS_membarrier, 1<<3, 0)) {
1405                 sem_init(&barrier_sem, 0, 0);
1406                 struct sigaction sa = {
1407                         .sa_flags = SA_RESTART,
1408                         .sa_handler = bcast_barrier
1409                 };
1410                 memset(&sa.sa_mask, -1, sizeof sa.sa_mask);
1411                 __libc_sigaction(SIGSYNCCALL, &sa, 0);
1412                 for (td=self->next; td!=self; td=td->next)
1413                         if (j) __syscall(SYS_tkill, td->tid, SIGSYNCCALL);
1414                 for (td=self->next; td!=self; td=td->next)
1415                         sem_wait(&barrier_sem);
1416                 sa.sa_handler = SIG_IGN;
1417                 __libc_sigaction(SIGSYNCCALL, &sa, 0);
1418                 sem_destroy(&barrier_sem);
1419         }
1420
1421         /* Install new dtv for each thread. */
1422         for (j=0, td=self; !j || td!=self; j++, td=td->next) {
1423                 td->dtv = td->dtv_copy = newdtv[j];
1424         }
1425
1426         __tl_unlock();
1427         __restore_sigs(&set);
1428 }
1429
1430 /* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
1431  * following stage 2 and stage 3 functions via primitive symbolic lookup
1432  * since it does not have access to their addresses to begin with. */
1433
1434 /* Stage 2 of the dynamic linker is called after relative relocations
1435  * have been processed. It can make function calls to static functions
1436  * and access string literals and static data, but cannot use extern
1437  * symbols. Its job is to perform symbolic relocations on the dynamic
1438  * linker itself, but some of the relocations performed may need to be
1439  * replaced later due to copy relocations in the main program. */
1440
1441 hidden void __dls2(unsigned char *base, size_t *sp)
1442 {
1443         if (DL_FDPIC) {
1444                 void *p1 = (void *)sp[-2];
1445                 void *p2 = (void *)sp[-1];
1446                 if (!p1) {
1447                         size_t *auxv, aux[AUX_CNT];
1448                         for (auxv=sp+1+*sp+1; *auxv; auxv++);
1449                         auxv++;
1450                         decode_vec(auxv, aux, AUX_CNT);
1451                         if (aux[AT_BASE]) ldso.base = (void *)aux[AT_BASE];
1452                         else ldso.base = (void *)(aux[AT_PHDR] & -4096);
1453                 }
1454                 app_loadmap = p2 ? p1 : 0;
1455                 ldso.loadmap = p2 ? p2 : p1;
1456                 ldso.base = laddr(&ldso, 0);
1457         } else {
1458                 ldso.base = base;
1459         }
1460         Ehdr *ehdr = (void *)ldso.base;
1461         ldso.name = ldso.shortname = "libc.so";
1462         ldso.phnum = ehdr->e_phnum;
1463         ldso.phdr = laddr(&ldso, ehdr->e_phoff);
1464         ldso.phentsize = ehdr->e_phentsize;
1465         kernel_mapped_dso(&ldso);
1466         decode_dyn(&ldso);
1467
1468         if (DL_FDPIC) makefuncdescs(&ldso);
1469
1470         /* Prepare storage for to save clobbered REL addends so they
1471          * can be reused in stage 3. There should be very few. If
1472          * something goes wrong and there are a huge number, abort
1473          * instead of risking stack overflow. */
1474         size_t dyn[DYN_CNT];
1475         decode_vec(ldso.dynv, dyn, DYN_CNT);
1476         size_t *rel = laddr(&ldso, dyn[DT_REL]);
1477         size_t rel_size = dyn[DT_RELSZ];
1478         size_t symbolic_rel_cnt = 0;
1479         apply_addends_to = rel;
1480         for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t))
1481                 if (!IS_RELATIVE(rel[1], ldso.syms)) symbolic_rel_cnt++;
1482         if (symbolic_rel_cnt >= ADDEND_LIMIT) a_crash();
1483         size_t addends[symbolic_rel_cnt+1];
1484         saved_addends = addends;
1485
1486         head = &ldso;
1487         reloc_all(&ldso);
1488
1489         ldso.relocated = 0;
1490
1491         /* Call dynamic linker stage-2b, __dls2b, looking it up
1492          * symbolically as a barrier against moving the address
1493          * load across the above relocation processing. */
1494         struct symdef dls2b_def = find_sym(&ldso, "__dls2b", 0);
1495         if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls2b_def.sym-ldso.syms])(sp);
1496         else ((stage3_func)laddr(&ldso, dls2b_def.sym->st_value))(sp);
1497 }
1498
1499 /* Stage 2b sets up a valid thread pointer, which requires relocations
1500  * completed in stage 2, and on which stage 3 is permitted to depend.
1501  * This is done as a separate stage, with symbolic lookup as a barrier,
1502  * so that loads of the thread pointer and &errno can be pure/const and
1503  * thereby hoistable. */
1504
1505 _Noreturn void __dls2b(size_t *sp)
1506 {
1507         /* Setup early thread pointer in builtin_tls for ldso/libc itself to
1508          * use during dynamic linking. If possible it will also serve as the
1509          * thread pointer at runtime. */
1510         libc.tls_size = sizeof builtin_tls;
1511         libc.tls_align = tls_align;
1512         if (__init_tp(__copy_tls((void *)builtin_tls)) < 0) {
1513                 a_crash();
1514         }
1515
1516         struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
1517         if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls3_def.sym-ldso.syms])(sp);
1518         else ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp);
1519 }
1520
1521 /* Stage 3 of the dynamic linker is called with the dynamic linker/libc
1522  * fully functional. Its job is to load (if not already loaded) and
1523  * process dependencies and relocations for the main application and
1524  * transfer control to its entry point. */
1525
1526 _Noreturn void __dls3(size_t *sp)
1527 {
1528         static struct dso app, vdso;
1529         size_t aux[AUX_CNT], *auxv;
1530         size_t i;
1531         char *env_preload=0;
1532         char *replace_argv0=0;
1533         size_t vdso_base;
1534         int argc = *sp;
1535         char **argv = (void *)(sp+1);
1536         char **argv_orig = argv;
1537         char **envp = argv+argc+1;
1538
1539         /* Find aux vector just past environ[] and use it to initialize
1540          * global data that may be needed before we can make syscalls. */
1541         __environ = envp;
1542         for (i=argc+1; argv[i]; i++);
1543         libc.auxv = auxv = (void *)(argv+i+1);
1544         decode_vec(auxv, aux, AUX_CNT);
1545         __hwcap = aux[AT_HWCAP];
1546         libc.page_size = aux[AT_PAGESZ];
1547         libc.secure = ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1548                 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]);
1549
1550         /* Only trust user/env if kernel says we're not suid/sgid */
1551         if (!libc.secure) {
1552                 env_path = getenv("LD_LIBRARY_PATH");
1553                 env_preload = getenv("LD_PRELOAD");
1554         }
1555
1556         /* If the main program was already loaded by the kernel,
1557          * AT_PHDR will point to some location other than the dynamic
1558          * linker's program headers. */
1559         if (aux[AT_PHDR] != (size_t)ldso.phdr) {
1560                 size_t interp_off = 0;
1561                 size_t tls_image = 0;
1562                 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1563                 Phdr *phdr = app.phdr = (void *)aux[AT_PHDR];
1564                 app.phnum = aux[AT_PHNUM];
1565                 app.phentsize = aux[AT_PHENT];
1566                 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1567                         if (phdr->p_type == PT_PHDR)
1568                                 app.base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1569                         else if (phdr->p_type == PT_INTERP)
1570                                 interp_off = (size_t)phdr->p_vaddr;
1571                         else if (phdr->p_type == PT_TLS) {
1572                                 tls_image = phdr->p_vaddr;
1573                                 app.tls.len = phdr->p_filesz;
1574                                 app.tls.size = phdr->p_memsz;
1575                                 app.tls.align = phdr->p_align;
1576                         }
1577                 }
1578                 if (DL_FDPIC) app.loadmap = app_loadmap;
1579                 if (app.tls.size) app.tls.image = laddr(&app, tls_image);
1580                 if (interp_off) ldso.name = laddr(&app, interp_off);
1581                 if ((aux[0] & (1UL<<AT_EXECFN))
1582                     && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1583                         app.name = (char *)aux[AT_EXECFN];
1584                 else
1585                         app.name = argv[0];
1586                 kernel_mapped_dso(&app);
1587         } else {
1588                 int fd;
1589                 char *ldname = argv[0];
1590                 size_t l = strlen(ldname);
1591                 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1592                 argv++;
1593                 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1594                         char *opt = argv[0]+2;
1595                         *argv++ = (void *)-1;
1596                         if (!*opt) {
1597                                 break;
1598                         } else if (!memcmp(opt, "list", 5)) {
1599                                 ldd_mode = 1;
1600                         } else if (!memcmp(opt, "library-path", 12)) {
1601                                 if (opt[12]=='=') env_path = opt+13;
1602                                 else if (opt[12]) *argv = 0;
1603                                 else if (*argv) env_path = *argv++;
1604                         } else if (!memcmp(opt, "preload", 7)) {
1605                                 if (opt[7]=='=') env_preload = opt+8;
1606                                 else if (opt[7]) *argv = 0;
1607                                 else if (*argv) env_preload = *argv++;
1608                         } else if (!memcmp(opt, "argv0", 5)) {
1609                                 if (opt[5]=='=') replace_argv0 = opt+6;
1610                                 else if (opt[5]) *argv = 0;
1611                                 else if (*argv) replace_argv0 = *argv++;
1612                         } else {
1613                                 argv[0] = 0;
1614                         }
1615                 }
1616                 argv[-1] = (void *)(argc - (argv-argv_orig));
1617                 if (!argv[0]) {
1618                         dprintf(2, "musl libc (" LDSO_ARCH ")\n"
1619                                 "Version %s\n"
1620                                 "Dynamic Program Loader\n"
1621                                 "Usage: %s [options] [--] pathname%s\n",
1622                                 __libc_version, ldname,
1623                                 ldd_mode ? "" : " [args]");
1624                         _exit(1);
1625                 }
1626                 fd = open(argv[0], O_RDONLY);
1627                 if (fd < 0) {
1628                         dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1629                         _exit(1);
1630                 }
1631                 Ehdr *ehdr = (void *)map_library(fd, &app);
1632                 if (!ehdr) {
1633                         dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1634                         _exit(1);
1635                 }
1636                 close(fd);
1637                 ldso.name = ldname;
1638                 app.name = argv[0];
1639                 aux[AT_ENTRY] = (size_t)laddr(&app, ehdr->e_entry);
1640                 /* Find the name that would have been used for the dynamic
1641                  * linker had ldd not taken its place. */
1642                 if (ldd_mode) {
1643                         for (i=0; i<app.phnum; i++) {
1644                                 if (app.phdr[i].p_type == PT_INTERP)
1645                                         ldso.name = laddr(&app, app.phdr[i].p_vaddr);
1646                         }
1647                         dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
1648                 }
1649         }
1650         if (app.tls.size) {
1651                 libc.tls_head = tls_tail = &app.tls;
1652                 app.tls_id = tls_cnt = 1;
1653 #ifdef TLS_ABOVE_TP
1654                 app.tls.offset = GAP_ABOVE_TP;
1655                 app.tls.offset += -GAP_ABOVE_TP & (app.tls.align-1);
1656                 tls_offset = app.tls.offset + app.tls.size
1657                         + ( -((uintptr_t)app.tls.image + app.tls.size)
1658                         & (app.tls.align-1) );
1659 #else
1660                 tls_offset = app.tls.offset = app.tls.size
1661                         + ( -((uintptr_t)app.tls.image + app.tls.size)
1662                         & (app.tls.align-1) );
1663 #endif
1664                 tls_align = MAXP2(tls_align, app.tls.align);
1665         }
1666         decode_dyn(&app);
1667         if (DL_FDPIC) {
1668                 makefuncdescs(&app);
1669                 if (!app.loadmap) {
1670                         app.loadmap = (void *)&app_dummy_loadmap;
1671                         app.loadmap->nsegs = 1;
1672                         app.loadmap->segs[0].addr = (size_t)app.map;
1673                         app.loadmap->segs[0].p_vaddr = (size_t)app.map
1674                                 - (size_t)app.base;
1675                         app.loadmap->segs[0].p_memsz = app.map_len;
1676                 }
1677                 argv[-3] = (void *)app.loadmap;
1678         }
1679
1680         /* Initial dso chain consists only of the app. */
1681         head = tail = syms_tail = &app;
1682
1683         /* Donate unused parts of app and library mapping to malloc */
1684         reclaim_gaps(&app);
1685         reclaim_gaps(&ldso);
1686
1687         /* Load preload/needed libraries, add symbols to global namespace. */
1688         if (env_preload) load_preload(env_preload);
1689         load_deps(&app);
1690         for (struct dso *p=head; p; p=p->next)
1691                 add_syms(p);
1692
1693         /* Attach to vdso, if provided by the kernel, last so that it does
1694          * not become part of the global namespace.  */
1695         if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR) && vdso_base) {
1696                 Ehdr *ehdr = (void *)vdso_base;
1697                 Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
1698                 vdso.phnum = ehdr->e_phnum;
1699                 vdso.phentsize = ehdr->e_phentsize;
1700                 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1701                         if (phdr->p_type == PT_DYNAMIC)
1702                                 vdso.dynv = (void *)(vdso_base + phdr->p_offset);
1703                         if (phdr->p_type == PT_LOAD)
1704                                 vdso.base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1705                 }
1706                 vdso.name = "";
1707                 vdso.shortname = "linux-gate.so.1";
1708                 vdso.relocated = 1;
1709                 decode_dyn(&vdso);
1710                 vdso.prev = tail;
1711                 tail->next = &vdso;
1712                 tail = &vdso;
1713         }
1714
1715         for (i=0; app.dynv[i]; i+=2) {
1716                 if (!DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG)
1717                         app.dynv[i+1] = (size_t)&debug;
1718                 if (DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG_INDIRECT) {
1719                         size_t *ptr = (size_t *) app.dynv[i+1];
1720                         *ptr = (size_t)&debug;
1721                 }
1722         }
1723
1724         /* The main program must be relocated LAST since it may contin
1725          * copy relocations which depend on libraries' relocations. */
1726         reloc_all(app.next);
1727         reloc_all(&app);
1728
1729         update_tls_size();
1730         if (libc.tls_size > sizeof builtin_tls || tls_align > MIN_TLS_ALIGN) {
1731                 void *initial_tls = calloc(libc.tls_size, 1);
1732                 if (!initial_tls) {
1733                         dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1734                                 argv[0], libc.tls_size);
1735                         _exit(127);
1736                 }
1737                 if (__init_tp(__copy_tls(initial_tls)) < 0) {
1738                         a_crash();
1739                 }
1740         } else {
1741                 size_t tmp_tls_size = libc.tls_size;
1742                 pthread_t self = __pthread_self();
1743                 /* Temporarily set the tls size to the full size of
1744                  * builtin_tls so that __copy_tls will use the same layout
1745                  * as it did for before. Then check, just to be safe. */
1746                 libc.tls_size = sizeof builtin_tls;
1747                 if (__copy_tls((void*)builtin_tls) != self) a_crash();
1748                 libc.tls_size = tmp_tls_size;
1749         }
1750         static_tls_cnt = tls_cnt;
1751
1752         if (ldso_fail) _exit(127);
1753         if (ldd_mode) _exit(0);
1754
1755         /* Determine if malloc was interposed by a replacement implementation
1756          * so that calloc and the memalign family can harden against the
1757          * possibility of incomplete replacement. */
1758         if (find_sym(head, "malloc", 1).dso != &ldso)
1759                 __malloc_replaced = 1;
1760
1761         /* Switch to runtime mode: any further failures in the dynamic
1762          * linker are a reportable failure rather than a fatal startup
1763          * error. */
1764         runtime = 1;
1765
1766         debug.ver = 1;
1767         debug.bp = dl_debug_state;
1768         debug.head = head;
1769         debug.base = ldso.base;
1770         debug.state = 0;
1771         _dl_debug_state();
1772
1773         if (replace_argv0) argv[0] = replace_argv0;
1774
1775         errno = 0;
1776
1777         CRTJMP((void *)aux[AT_ENTRY], argv-1);
1778         for(;;);
1779 }
1780
1781 static void prepare_lazy(struct dso *p)
1782 {
1783         size_t dyn[DYN_CNT], n, flags1=0;
1784         decode_vec(p->dynv, dyn, DYN_CNT);
1785         search_vec(p->dynv, &flags1, DT_FLAGS_1);
1786         if (dyn[DT_BIND_NOW] || (dyn[DT_FLAGS] & DF_BIND_NOW) || (flags1 & DF_1_NOW))
1787                 return;
1788         n = dyn[DT_RELSZ]/2 + dyn[DT_RELASZ]/3 + dyn[DT_PLTRELSZ]/2 + 1;
1789         if (NEED_MIPS_GOT_RELOCS) {
1790                 size_t j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1791                 size_t i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1792                 n += i-j;
1793         }
1794         p->lazy = calloc(n, 3*sizeof(size_t));
1795         if (!p->lazy) {
1796                 error("Error preparing lazy relocation for %s: %m", p->name);
1797                 longjmp(*rtld_fail, 1);
1798         }
1799         p->lazy_next = lazy_head;
1800         lazy_head = p;
1801 }
1802
1803 void *dlopen(const char *file, int mode)
1804 {
1805         struct dso *volatile p, *orig_tail, *orig_syms_tail, *orig_lazy_head, *next;
1806         struct tls_module *orig_tls_tail;
1807         size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1808         size_t i;
1809         int cs;
1810         jmp_buf jb;
1811
1812         if (!file) return head;
1813
1814         pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1815         pthread_rwlock_wrlock(&lock);
1816         __inhibit_ptc();
1817
1818         p = 0;
1819         orig_tls_tail = tls_tail;
1820         orig_tls_cnt = tls_cnt;
1821         orig_tls_offset = tls_offset;
1822         orig_tls_align = tls_align;
1823         orig_lazy_head = lazy_head;
1824         orig_syms_tail = syms_tail;
1825         orig_tail = tail;
1826         noload = mode & RTLD_NOLOAD;
1827
1828         rtld_fail = &jb;
1829         if (setjmp(*rtld_fail)) {
1830                 /* Clean up anything new that was (partially) loaded */
1831                 revert_syms(orig_syms_tail);
1832                 for (p=orig_tail->next; p; p=next) {
1833                         next = p->next;
1834                         while (p->td_index) {
1835                                 void *tmp = p->td_index->next;
1836                                 free(p->td_index);
1837                                 p->td_index = tmp;
1838                         }
1839                         free(p->funcdescs);
1840                         if (p->rpath != p->rpath_orig)
1841                                 free(p->rpath);
1842                         if (p->deps != &nodeps_dummy)
1843                                 free(p->deps);
1844                         unmap_library(p);
1845                         free(p);
1846                 }
1847                 if (!orig_tls_tail) libc.tls_head = 0;
1848                 tls_tail = orig_tls_tail;
1849                 if (tls_tail) tls_tail->next = 0;
1850                 tls_cnt = orig_tls_cnt;
1851                 tls_offset = orig_tls_offset;
1852                 tls_align = orig_tls_align;
1853                 lazy_head = orig_lazy_head;
1854                 tail = orig_tail;
1855                 tail->next = 0;
1856                 p = 0;
1857                 goto end;
1858         } else p = load_library(file, head);
1859
1860         if (!p) {
1861                 error(noload ?
1862                         "Library %s is not already loaded" :
1863                         "Error loading shared library %s: %m",
1864                         file);
1865                 goto end;
1866         }
1867
1868         /* First load handling */
1869         int first_load = !p->deps;
1870         if (first_load) {
1871                 load_deps(p);
1872                 if (!p->relocated && (mode & RTLD_LAZY)) {
1873                         prepare_lazy(p);
1874                         for (i=0; p->deps[i]; i++)
1875                                 if (!p->deps[i]->relocated)
1876                                         prepare_lazy(p->deps[i]);
1877                 }
1878         }
1879         if (first_load || (mode & RTLD_GLOBAL)) {
1880                 /* Make new symbols global, at least temporarily, so we can do
1881                  * relocations. If not RTLD_GLOBAL, this is reverted below. */
1882                 add_syms(p);
1883                 for (i=0; p->deps[i]; i++)
1884                         add_syms(p->deps[i]);
1885         }
1886         if (first_load) {
1887                 reloc_all(p);
1888         }
1889
1890         /* If RTLD_GLOBAL was not specified, undo any new additions
1891          * to the global symbol table. This is a nop if the library was
1892          * previously loaded and already global. */
1893         if (!(mode & RTLD_GLOBAL))
1894                 revert_syms(orig_syms_tail);
1895
1896         /* Processing of deferred lazy relocations must not happen until
1897          * the new libraries are committed; otherwise we could end up with
1898          * relocations resolved to symbol definitions that get removed. */
1899         redo_lazy_relocs();
1900
1901         update_tls_size();
1902         if (tls_cnt != orig_tls_cnt)
1903                 install_new_tls();
1904         _dl_debug_state();
1905         orig_tail = tail;
1906 end:
1907         __release_ptc();
1908         if (p) gencnt++;
1909         pthread_rwlock_unlock(&lock);
1910         if (p) do_init_fini(orig_tail);
1911         pthread_setcancelstate(cs, 0);
1912         return p;
1913 }
1914
1915 hidden int __dl_invalid_handle(void *h)
1916 {
1917         struct dso *p;
1918         for (p=head; p; p=p->next) if (h==p) return 0;
1919         error("Invalid library handle %p", (void *)h);
1920         return 1;
1921 }
1922
1923 static void *addr2dso(size_t a)
1924 {
1925         struct dso *p;
1926         size_t i;
1927         if (DL_FDPIC) for (p=head; p; p=p->next) {
1928                 i = count_syms(p);
1929                 if (a-(size_t)p->funcdescs < i*sizeof(*p->funcdescs))
1930                         return p;
1931         }
1932         for (p=head; p; p=p->next) {
1933                 if (DL_FDPIC && p->loadmap) {
1934                         for (i=0; i<p->loadmap->nsegs; i++) {
1935                                 if (a-p->loadmap->segs[i].p_vaddr
1936                                     < p->loadmap->segs[i].p_memsz)
1937                                         return p;
1938                         }
1939                 } else {
1940                         Phdr *ph = p->phdr;
1941                         size_t phcnt = p->phnum;
1942                         size_t entsz = p->phentsize;
1943                         size_t base = (size_t)p->base;
1944                         for (; phcnt--; ph=(void *)((char *)ph+entsz)) {
1945                                 if (ph->p_type != PT_LOAD) continue;
1946                                 if (a-base-ph->p_vaddr < ph->p_memsz)
1947                                         return p;
1948                         }
1949                         if (a-(size_t)p->map < p->map_len)
1950                                 return 0;
1951                 }
1952         }
1953         return 0;
1954 }
1955
1956 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1957 {
1958         size_t i;
1959         uint32_t h = 0, gh = 0, *ght;
1960         Sym *sym;
1961         if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1962                 if (p == RTLD_DEFAULT) {
1963                         p = head;
1964                 } else if (p == RTLD_NEXT) {
1965                         p = addr2dso((size_t)ra);
1966                         if (!p) p=head;
1967                         p = p->next;
1968                 }
1969                 struct symdef def = find_sym(p, s, 0);
1970                 if (!def.sym) goto failed;
1971                 if ((def.sym->st_info&0xf) == STT_TLS)
1972                         return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value-DTP_OFFSET});
1973                 if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
1974                         return def.dso->funcdescs + (def.sym - def.dso->syms);
1975                 return laddr(def.dso, def.sym->st_value);
1976         }
1977         if (__dl_invalid_handle(p))
1978                 return 0;
1979         if ((ght = p->ghashtab)) {
1980                 gh = gnu_hash(s);
1981                 sym = gnu_lookup(gh, ght, p, s);
1982         } else {
1983                 h = sysv_hash(s);
1984                 sym = sysv_lookup(s, h, p);
1985         }
1986         if (sym && (sym->st_info&0xf) == STT_TLS)
1987                 return __tls_get_addr((tls_mod_off_t []){p->tls_id, sym->st_value-DTP_OFFSET});
1988         if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
1989                 return p->funcdescs + (sym - p->syms);
1990         if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1991                 return laddr(p, sym->st_value);
1992         for (i=0; p->deps[i]; i++) {
1993                 if ((ght = p->deps[i]->ghashtab)) {
1994                         if (!gh) gh = gnu_hash(s);
1995                         sym = gnu_lookup(gh, ght, p->deps[i], s);
1996                 } else {
1997                         if (!h) h = sysv_hash(s);
1998                         sym = sysv_lookup(s, h, p->deps[i]);
1999                 }
2000                 if (sym && (sym->st_info&0xf) == STT_TLS)
2001                         return __tls_get_addr((tls_mod_off_t []){p->deps[i]->tls_id, sym->st_value-DTP_OFFSET});
2002                 if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
2003                         return p->deps[i]->funcdescs + (sym - p->deps[i]->syms);
2004                 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
2005                         return laddr(p->deps[i], sym->st_value);
2006         }
2007 failed:
2008         error("Symbol not found: %s", s);
2009         return 0;
2010 }
2011
2012 int dladdr(const void *addr_arg, Dl_info *info)
2013 {
2014         size_t addr = (size_t)addr_arg;
2015         struct dso *p;
2016         Sym *sym, *bestsym;
2017         uint32_t nsym;
2018         char *strings;
2019         size_t best = 0;
2020         size_t besterr = -1;
2021
2022         pthread_rwlock_rdlock(&lock);
2023         p = addr2dso(addr);
2024         pthread_rwlock_unlock(&lock);
2025
2026         if (!p) return 0;
2027
2028         sym = p->syms;
2029         strings = p->strings;
2030         nsym = count_syms(p);
2031
2032         if (DL_FDPIC) {
2033                 size_t idx = (addr-(size_t)p->funcdescs)
2034                         / sizeof(*p->funcdescs);
2035                 if (idx < nsym && (sym[idx].st_info&0xf) == STT_FUNC) {
2036                         best = (size_t)(p->funcdescs + idx);
2037                         bestsym = sym + idx;
2038                         besterr = 0;
2039                 }
2040         }
2041
2042         if (!best) for (; nsym; nsym--, sym++) {
2043                 if (sym->st_value
2044                  && (1<<(sym->st_info&0xf) & OK_TYPES)
2045                  && (1<<(sym->st_info>>4) & OK_BINDS)) {
2046                         size_t symaddr = (size_t)laddr(p, sym->st_value);
2047                         if (symaddr > addr || symaddr <= best)
2048                                 continue;
2049                         best = symaddr;
2050                         bestsym = sym;
2051                         besterr = addr - symaddr;
2052                         if (addr == symaddr)
2053                                 break;
2054                 }
2055         }
2056
2057         if (bestsym && besterr > bestsym->st_size-1) {
2058                 best = 0;
2059                 bestsym = 0;
2060         }
2061
2062         info->dli_fname = p->name;
2063         info->dli_fbase = p->map;
2064
2065         if (!best) {
2066                 info->dli_sname = 0;
2067                 info->dli_saddr = 0;
2068                 return 1;
2069         }
2070
2071         if (DL_FDPIC && (bestsym->st_info&0xf) == STT_FUNC)
2072                 best = (size_t)(p->funcdescs + (bestsym - p->syms));
2073         info->dli_sname = strings + bestsym->st_name;
2074         info->dli_saddr = (void *)best;
2075
2076         return 1;
2077 }
2078
2079 hidden void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
2080 {
2081         void *res;
2082         pthread_rwlock_rdlock(&lock);
2083         res = do_dlsym(p, s, ra);
2084         pthread_rwlock_unlock(&lock);
2085         return res;
2086 }
2087
2088 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
2089 {
2090         struct dso *current;
2091         struct dl_phdr_info info;
2092         int ret = 0;
2093         for(current = head; current;) {
2094                 info.dlpi_addr      = (uintptr_t)current->base;
2095                 info.dlpi_name      = current->name;
2096                 info.dlpi_phdr      = current->phdr;
2097                 info.dlpi_phnum     = current->phnum;
2098                 info.dlpi_adds      = gencnt;
2099                 info.dlpi_subs      = 0;
2100                 info.dlpi_tls_modid = current->tls_id;
2101                 info.dlpi_tls_data  = current->tls.image;
2102
2103                 ret = (callback)(&info, sizeof (info), data);
2104
2105                 if (ret != 0) break;
2106
2107                 pthread_rwlock_rdlock(&lock);
2108                 current = current->next;
2109                 pthread_rwlock_unlock(&lock);
2110         }
2111         return ret;
2112 }
2113
2114 static void error(const char *fmt, ...)
2115 {
2116         va_list ap;
2117         va_start(ap, fmt);
2118         if (!runtime) {
2119                 vdprintf(2, fmt, ap);
2120                 dprintf(2, "\n");
2121                 ldso_fail = 1;
2122                 va_end(ap);
2123                 return;
2124         }
2125         __dl_vseterr(fmt, ap);
2126         va_end(ap);
2127 }