src/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 "pthread_impl.h"
  21 #include "libc.h"
  22 #include "dynlink.h"
  23
  24 static void error(const char *, ...);
  25
  26 #ifdef SHARED
  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         unsigned char *base;
  46         char *name;
  47         size_t *dynv;
  48         struct dso *next, *prev;
  49
  50         Phdr *phdr;
  51         int phnum;
  52         size_t phentsize;
  53         int refcnt;
  54         Sym *syms;
  55         uint32_t *hashtab;
  56         uint32_t *ghashtab;
  57         int16_t *versym;
  58         char *strings;
  59         unsigned char *map;
  60         size_t map_len;
  61         dev_t dev;
  62         ino_t ino;
  63         signed char global;
  64         char relocated;
  65         char constructed;
  66         char kernel_mapped;
  67         struct dso **deps, *needed_by;
  68         char *rpath_orig, *rpath;
  69         void *tls_image;
  70         size_t tls_len, tls_size, tls_align, tls_id, tls_offset;
  71         size_t relro_start, relro_end;
  72         void **new_dtv;
  73         unsigned char *new_tls;
  74         volatile int new_dtv_idx, new_tls_idx;
  75         struct td_index *td_index;
  76         struct dso *fini_next;
  77         char *shortname;
  78         char buf[];
  79 };
  80
  81 struct symdef {
  82         Sym *sym;
  83         struct dso *dso;
  84 };
  85
  86 int __init_tp(void *);
  87 void __init_libc(char **, char *);
  88
  89 const char *__libc_get_version(void);
  90
  91 static struct builtin_tls {
  92         char c;
  93         struct pthread pt;
  94         void *space[16];
  95 } builtin_tls[1];
  96 #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
  97
  98 #define ADDEND_LIMIT 4096
  99 static size_t *saved_addends, *apply_addends_to;
 100
 101 static struct dso ldso;
 102 static struct dso *head, *tail, *fini_head;
 103 static char *env_path, *sys_path;
 104 static unsigned long long gencnt;
 105 static int runtime;
 106 static int ldd_mode;
 107 static int ldso_fail;
 108 static int noload;
 109 static jmp_buf *rtld_fail;
 110 static pthread_rwlock_t lock;
 111 static struct debug debug;
 112 static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
 113 static size_t static_tls_cnt;
 114 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
 115
 116 struct debug *_dl_debug_addr = &debug;
 117
 118 static int dl_strcmp(const char *l, const char *r)
 119 {
 120         for (; *l==*r && *l; l++, r++);
 121         return *(unsigned char *)l - *(unsigned char *)r;
 122 }
 123 #define strcmp(l,r) dl_strcmp(l,r)
 124
 125 static void decode_vec(size_t *v, size_t *a, size_t cnt)
 126 {
 127         size_t i;
 128         for (i=0; i<cnt; i++) a[i] = 0;
 129         for (; v[0]; v+=2) if (v[0]-1<cnt-1) {
 130                 a[0] |= 1UL<<v[0];
 131                 a[v[0]] = v[1];
 132         }
 133 }
 134
 135 static int search_vec(size_t *v, size_t *r, size_t key)
 136 {
 137         for (; v[0]!=key; v+=2)
 138                 if (!v[0]) return 0;
 139         *r = v[1];
 140         return 1;
 141 }
 142
 143 static uint32_t sysv_hash(const char *s0)
 144 {
 145         const unsigned char *s = (void *)s0;
 146         uint_fast32_t h = 0;
 147         while (*s) {
 148                 h = 16*h + *s++;
 149                 h ^= h>>24 & 0xf0;
 150         }
 151         return h & 0xfffffff;
 152 }
 153
 154 static uint32_t gnu_hash(const char *s0)
 155 {
 156         const unsigned char *s = (void *)s0;
 157         uint_fast32_t h = 5381;
 158         for (; *s; s++)
 159                 h = h*33 + *s;
 160         return h;
 161 }
 162
 163 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
 164 {
 165         size_t i;
 166         Sym *syms = dso->syms;
 167         uint32_t *hashtab = dso->hashtab;
 168         char *strings = dso->strings;
 169         for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
 170                 if ((!dso->versym || dso->versym[i] >= 0)
 171                     && (!strcmp(s, strings+syms[i].st_name)))
 172                         return syms+i;
 173         }
 174         return 0;
 175 }
 176
 177 static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso)
 178 {
 179         Sym *syms = dso->syms;
 180         char *strings = dso->strings;
 181         uint32_t *hashtab = dso->ghashtab;
 182         uint32_t nbuckets = hashtab[0];
 183         uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
 184         uint32_t h2;
 185         uint32_t *hashval;
 186         uint32_t i = buckets[h1 % nbuckets];
 187
 188         if (!i) return 0;
 189
 190         hashval = buckets + nbuckets + (i - hashtab[1]);
 191
 192         for (h1 |= 1; ; i++) {
 193                 h2 = *hashval++;
 194                 if ((!dso->versym || dso->versym[i] >= 0)
 195                     && (h1 == (h2|1)) && !strcmp(s, strings + syms[i].st_name))
 196                         return syms+i;
 197                 if (h2 & 1) break;
 198         }
 199
 200         return 0;
 201 }
 202
 203 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
 204 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
 205
 206 #ifndef ARCH_SYM_REJECT_UND
 207 #define ARCH_SYM_REJECT_UND(s) 0
 208 #endif
 209
 210 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
 211 {
 212         uint32_t h = 0, gh = 0;
 213         struct symdef def = {0};
 214         for (; dso; dso=dso->next) {
 215                 Sym *sym;
 216                 if (!dso->global) continue;
 217                 if (dso->ghashtab) {
 218                         if (!gh) gh = gnu_hash(s);
 219                         sym = gnu_lookup(s, gh, dso);
 220                 } else {
 221                         if (!h) h = sysv_hash(s);
 222                         sym = sysv_lookup(s, h, dso);
 223                 }
 224                 if (!sym) continue;
 225                 if (!sym->st_shndx)
 226                         if (need_def || (sym->st_info&0xf) == STT_TLS
 227                             || ARCH_SYM_REJECT_UND(sym))
 228                                 continue;
 229                 if (!sym->st_value)
 230                         if ((sym->st_info&0xf) != STT_TLS)
 231                                 continue;
 232                 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
 233                 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
 234
 235                 if (def.sym && sym->st_info>>4 == STB_WEAK) continue;
 236                 def.sym = sym;
 237                 def.dso = dso;
 238                 if (sym->st_info>>4 == STB_GLOBAL) break;
 239         }
 240         return def;
 241 }
 242
 243 __attribute__((__visibility__("hidden")))
 244 ptrdiff_t __tlsdesc_static(), __tlsdesc_dynamic();
 245
 246 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
 247 {
 248         unsigned char *base = dso->base;
 249         Sym *syms = dso->syms;
 250         char *strings = dso->strings;
 251         Sym *sym;
 252         const char *name;
 253         void *ctx;
 254         int type;
 255         int sym_index;
 256         struct symdef def;
 257         size_t *reloc_addr;
 258         size_t sym_val;
 259         size_t tls_val;
 260         size_t addend;
 261         int skip_relative = 0, reuse_addends = 0, save_slot = 0;
 262
 263         if (dso == &ldso) {
 264                 /* Only ldso's REL table needs addend saving/reuse. */
 265                 if (rel == apply_addends_to)
 266                         reuse_addends = 1;
 267                 skip_relative = 1;
 268         }
 269
 270         for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
 271                 if (skip_relative && IS_RELATIVE(rel[1])) continue;
 272                 type = R_TYPE(rel[1]);
 273                 if (type == REL_NONE) continue;
 274                 sym_index = R_SYM(rel[1]);
 275                 reloc_addr = (void *)(base + rel[0]);
 276                 if (sym_index) {
 277                         sym = syms + sym_index;
 278                         name = strings + sym->st_name;
 279                         ctx = type==REL_COPY ? head->next : head;
 280                         def = find_sym(ctx, name, type==REL_PLT);
 281                         if (!def.sym && (sym->st_shndx != SHN_UNDEF
 282                             || sym->st_info>>4 != STB_WEAK)) {
 283                                 error("Error relocating %s: %s: symbol not found",
 284                                         dso->name, name);
 285                                 if (runtime) longjmp(*rtld_fail, 1);
 286                                 continue;
 287                         }
 288                 } else {
 289                         sym = 0;
 290                         def.sym = 0;
 291                         def.dso = dso;
 292                 }
 293
 294                 if (stride > 2) {
 295                         addend = rel[2];
 296                 } else if (type==REL_GOT || type==REL_PLT|| type==REL_COPY) {
 297                         addend = 0;
 298                 } else if (reuse_addends) {
 299                         /* Save original addend in stage 2 where the dso
 300                          * chain consists of just ldso; otherwise read back
 301                          * saved addend since the inline one was clobbered. */
 302                         if (head==&ldso)
 303                                 saved_addends[save_slot] = *reloc_addr;
 304                         addend = saved_addends[save_slot++];
 305                 } else {
 306                         addend = *reloc_addr;
 307                 }
 308
 309                 sym_val = def.sym ? (size_t)def.dso->base+def.sym->st_value : 0;
 310                 tls_val = def.sym ? def.sym->st_value : 0;
 311
 312                 switch(type) {
 313                 case REL_NONE:
 314                         break;
 315                 case REL_OFFSET:
 316                         addend -= (size_t)reloc_addr;
 317                 case REL_SYMBOLIC:
 318                 case REL_GOT:
 319                 case REL_PLT:
 320                         *reloc_addr = sym_val + addend;
 321                         break;
 322                 case REL_RELATIVE:
 323                         *reloc_addr = (size_t)base + addend;
 324                         break;
 325                 case REL_SYM_OR_REL:
 326                         if (sym) *reloc_addr = sym_val + addend;
 327                         else *reloc_addr = (size_t)base + addend;
 328                         break;
 329                 case REL_COPY:
 330                         memcpy(reloc_addr, (void *)sym_val, sym->st_size);
 331                         break;
 332                 case REL_OFFSET32:
 333                         *(uint32_t *)reloc_addr = sym_val + addend
 334                                 - (size_t)reloc_addr;
 335                         break;
 336                 case REL_DTPMOD:
 337                         *reloc_addr = def.dso->tls_id;
 338                         break;
 339                 case REL_DTPOFF:
 340                         *reloc_addr = tls_val + addend;
 341                         break;
 342 #ifdef TLS_ABOVE_TP
 343                 case REL_TPOFF:
 344                         *reloc_addr = tls_val + def.dso->tls_offset + TPOFF_K + addend;
 345                         break;
 346 #else
 347                 case REL_TPOFF:
 348                         *reloc_addr = tls_val - def.dso->tls_offset + addend;
 349                         break;
 350                 case REL_TPOFF_NEG:
 351                         *reloc_addr = def.dso->tls_offset - tls_val + addend;
 352                         break;
 353 #endif
 354                 case REL_TLSDESC:
 355                         if (stride<3) addend = reloc_addr[1];
 356                         if (runtime && def.dso->tls_id >= static_tls_cnt) {
 357                                 struct td_index *new = malloc(sizeof *new);
 358                                 if (!new) {
 359                                         error(
 360                                         "Error relocating %s: cannot allocate TLSDESC for %s",
 361                                         dso->name, sym ? name : "(local)" );
 362                                         longjmp(*rtld_fail, 1);
 363                                 }
 364                                 new->next = dso->td_index;
 365                                 dso->td_index = new;
 366                                 new->args[0] = def.dso->tls_id;
 367                                 new->args[1] = tls_val + addend;
 368                                 reloc_addr[0] = (size_t)__tlsdesc_dynamic;
 369                                 reloc_addr[1] = (size_t)new;
 370                         } else {
 371                                 reloc_addr[0] = (size_t)__tlsdesc_static;
 372 #ifdef TLS_ABOVE_TP
 373                                 reloc_addr[1] = tls_val + def.dso->tls_offset
 374                                         + TPOFF_K + addend;
 375 #else
 376                                 reloc_addr[1] = tls_val - def.dso->tls_offset
 377                                         + addend;
 378 #endif
 379                         }
 380                         break;
 381                 default:
 382                         error("Error relocating %s: unsupported relocation type %d",
 383                                 dso->name, type);
 384                         if (runtime) longjmp(*rtld_fail, 1);
 385                         continue;
 386                 }
 387         }
 388 }
 389
 390 /* A huge hack: to make up for the wastefulness of shared libraries
 391  * needing at least a page of dirty memory even if they have no global
 392  * data, we reclaim the gaps at the beginning and end of writable maps
 393  * and "donate" them to the heap by setting up minimal malloc
 394  * structures and then freeing them. */
 395
 396 static void reclaim(struct dso *dso, size_t start, size_t end)
 397 {
 398         size_t *a, *z;
 399         if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
 400         if (end   >= dso->relro_start && end   < dso->relro_end) end = dso->relro_start;
 401         start = start + 6*sizeof(size_t)-1 & -4*sizeof(size_t);
 402         end = (end & -4*sizeof(size_t)) - 2*sizeof(size_t);
 403         if (start>end || end-start < 4*sizeof(size_t)) return;
 404         a = (size_t *)(dso->base + start);
 405         z = (size_t *)(dso->base + end);
 406         a[-2] = 1;
 407         a[-1] = z[0] = end-start + 2*sizeof(size_t) | 1;
 408         z[1] = 1;
 409         free(a);
 410 }
 411
 412 static void reclaim_gaps(struct dso *dso)
 413 {
 414         Phdr *ph = dso->phdr;
 415         size_t phcnt = dso->phnum;
 416
 417         for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
 418                 if (ph->p_type!=PT_LOAD) continue;
 419                 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
 420                 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
 421                 reclaim(dso, ph->p_vaddr+ph->p_memsz,
 422                         ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
 423         }
 424 }
 425
 426 static void *map_library(int fd, struct dso *dso)
 427 {
 428         Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
 429         void *allocated_buf=0;
 430         size_t phsize;
 431         size_t addr_min=SIZE_MAX, addr_max=0, map_len;
 432         size_t this_min, this_max;
 433         off_t off_start;
 434         Ehdr *eh;
 435         Phdr *ph, *ph0;
 436         unsigned prot;
 437         unsigned char *map=MAP_FAILED, *base;
 438         size_t dyn=0;
 439         size_t tls_image=0;
 440         size_t i;
 441
 442         ssize_t l = read(fd, buf, sizeof buf);
 443         eh = buf;
 444         if (l<0) return 0;
 445         if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
 446                 goto noexec;
 447         phsize = eh->e_phentsize * eh->e_phnum;
 448         if (phsize > sizeof buf - sizeof *eh) {
 449                 allocated_buf = malloc(phsize);
 450                 if (!allocated_buf) return 0;
 451                 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
 452                 if (l < 0) goto error;
 453                 if (l != phsize) goto noexec;
 454                 ph = ph0 = allocated_buf;
 455         } else if (eh->e_phoff + phsize > l) {
 456                 l = pread(fd, buf+1, phsize, eh->e_phoff);
 457                 if (l < 0) goto error;
 458                 if (l != phsize) goto noexec;
 459                 ph = ph0 = (void *)(buf + 1);
 460         } else {
 461                 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
 462         }
 463         for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
 464                 if (ph->p_type == PT_DYNAMIC) {
 465                         dyn = ph->p_vaddr;
 466                 } else if (ph->p_type == PT_TLS) {
 467                         tls_image = ph->p_vaddr;
 468                         dso->tls_align = ph->p_align;
 469                         dso->tls_len = ph->p_filesz;
 470                         dso->tls_size = ph->p_memsz;
 471                 } else if (ph->p_type == PT_GNU_RELRO) {
 472                         dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
 473                         dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
 474                 }
 475                 if (ph->p_type != PT_LOAD) continue;
 476                 if (ph->p_vaddr < addr_min) {
 477                         addr_min = ph->p_vaddr;
 478                         off_start = ph->p_offset;
 479                         prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
 480                                 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
 481                                 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
 482                 }
 483                 if (ph->p_vaddr+ph->p_memsz > addr_max) {
 484                         addr_max = ph->p_vaddr+ph->p_memsz;
 485                 }
 486         }
 487         if (!dyn) goto noexec;
 488         addr_max += PAGE_SIZE-1;
 489         addr_max &= -PAGE_SIZE;
 490         addr_min &= -PAGE_SIZE;
 491         off_start &= -PAGE_SIZE;
 492         map_len = addr_max - addr_min + off_start;
 493         /* The first time, we map too much, possibly even more than
 494          * the length of the file. This is okay because we will not
 495          * use the invalid part; we just need to reserve the right
 496          * amount of virtual address space to map over later. */
 497         map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start);
 498         if (map==MAP_FAILED) goto error;
 499         /* If the loaded file is not relocatable and the requested address is
 500          * not available, then the load operation must fail. */
 501         if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
 502                 errno = EBUSY;
 503                 goto error;
 504         }
 505         base = map - addr_min;
 506         dso->phdr = 0;
 507         dso->phnum = 0;
 508         for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
 509                 if (ph->p_type != PT_LOAD) continue;
 510                 /* Check if the programs headers are in this load segment, and
 511                  * if so, record the address for use by dl_iterate_phdr. */
 512                 if (!dso->phdr && eh->e_phoff >= ph->p_offset
 513                     && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
 514                         dso->phdr = (void *)(base + ph->p_vaddr
 515                                 + (eh->e_phoff-ph->p_offset));
 516                         dso->phnum = eh->e_phnum;
 517                         dso->phentsize = eh->e_phentsize;
 518                 }
 519                 /* Reuse the existing mapping for the lowest-address LOAD */
 520                 if ((ph->p_vaddr & -PAGE_SIZE) == addr_min) continue;
 521                 this_min = ph->p_vaddr & -PAGE_SIZE;
 522                 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
 523                 off_start = ph->p_offset & -PAGE_SIZE;
 524                 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
 525                         ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
 526                         ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
 527                 if (mmap(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
 528                         goto error;
 529                 if (ph->p_memsz > ph->p_filesz) {
 530                         size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
 531                         size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
 532                         memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
 533                         if (pgbrk-(size_t)base < this_max && mmap((void *)pgbrk, (size_t)base+this_max-pgbrk, prot, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) == MAP_FAILED)
 534                                 goto error;
 535                 }
 536         }
 537         for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
 538                 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
 539                         if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC)
 540                             && errno != ENOSYS)
 541                                 goto error;
 542                         break;
 543                 }
 544         dso->map = map;
 545         dso->map_len = map_len;
 546         dso->base = base;
 547         dso->dynv = (void *)(base+dyn);
 548         if (dso->tls_size) dso->tls_image = (void *)(base+tls_image);
 549         if (!runtime) reclaim_gaps(dso);
 550         free(allocated_buf);
 551         return map;
 552 noexec:
 553         errno = ENOEXEC;
 554 error:
 555         if (map!=MAP_FAILED) munmap(map, map_len);
 556         free(allocated_buf);
 557         return 0;
 558 }
 559
 560 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
 561 {
 562         size_t l;
 563         int fd;
 564         for (;;) {
 565                 s += strspn(s, ":\n");
 566                 l = strcspn(s, ":\n");
 567                 if (l-1 >= INT_MAX) return -1;
 568                 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
 569                         if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
 570                         switch (errno) {
 571                         case ENOENT:
 572                         case ENOTDIR:
 573                         case EACCES:
 574                         case ENAMETOOLONG:
 575                                 break;
 576                         default:
 577                                 /* Any negative value but -1 will inhibit
 578                                  * futher path search. */
 579                                 return -2;
 580                         }
 581                 }
 582                 s += l;
 583         }
 584 }
 585
 586 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
 587 {
 588         size_t n, l;
 589         const char *s, *t, *origin;
 590         char *d;
 591         if (p->rpath || !p->rpath_orig) return 0;
 592         if (!strchr(p->rpath_orig, '$')) {
 593                 p->rpath = p->rpath_orig;
 594                 return 0;
 595         }
 596         n = 0;
 597         s = p->rpath_orig;
 598         while ((t=strchr(s, '$'))) {
 599                 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
 600                         return 0;
 601                 s = t+1;
 602                 n++;
 603         }
 604         if (n > SSIZE_MAX/PATH_MAX) return 0;
 605
 606         if (p->kernel_mapped) {
 607                 /* $ORIGIN searches cannot be performed for the main program
 608                  * when it is suid/sgid/AT_SECURE. This is because the
 609                  * pathname is under the control of the caller of execve.
 610                  * For libraries, however, $ORIGIN can be processed safely
 611                  * since the library's pathname came from a trusted source
 612                  * (either system paths or a call to dlopen). */
 613                 if (libc.secure)
 614                         return 0;
 615                 l = readlink("/proc/self/exe", buf, buf_size);
 616                 if (l == -1) switch (errno) {
 617                 case ENOENT:
 618                 case ENOTDIR:
 619                 case EACCES:
 620                         break;
 621                 default:
 622                         return -1;
 623                 }
 624                 if (l >= buf_size)
 625                         return 0;
 626                 buf[l] = 0;
 627                 origin = buf;
 628         } else {
 629                 origin = p->name;
 630         }
 631         t = strrchr(origin, '/');
 632         l = t ? t-origin : 0;
 633         p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
 634         if (!p->rpath) return -1;
 635
 636         d = p->rpath;
 637         s = p->rpath_orig;
 638         while ((t=strchr(s, '$'))) {
 639                 memcpy(d, s, t-s);
 640                 d += t-s;
 641                 memcpy(d, origin, l);
 642                 d += l;
 643                 /* It was determined previously that the '$' is followed
 644                  * either by "ORIGIN" or "{ORIGIN}". */
 645                 s = t + 7 + 2*(t[1]=='{');
 646         }
 647         strcpy(d, s);
 648         return 0;
 649 }
 650
 651 static void decode_dyn(struct dso *p)
 652 {
 653         size_t dyn[DYN_CNT];
 654         decode_vec(p->dynv, dyn, DYN_CNT);
 655         p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
 656         p->strings = (void *)(p->base + dyn[DT_STRTAB]);
 657         if (dyn[0]&(1<<DT_HASH))
 658                 p->hashtab = (void *)(p->base + dyn[DT_HASH]);
 659         if (dyn[0]&(1<<DT_RPATH))
 660                 p->rpath_orig = (void *)(p->strings + dyn[DT_RPATH]);
 661         if (dyn[0]&(1<<DT_RUNPATH))
 662                 p->rpath_orig = (void *)(p->strings + dyn[DT_RUNPATH]);
 663         if (search_vec(p->dynv, dyn, DT_GNU_HASH))
 664                 p->ghashtab = (void *)(p->base + *dyn);
 665         if (search_vec(p->dynv, dyn, DT_VERSYM))
 666                 p->versym = (void *)(p->base + *dyn);
 667 }
 668
 669 static struct dso *load_library(const char *name, struct dso *needed_by)
 670 {
 671         char buf[2*NAME_MAX+2];
 672         const char *pathname;
 673         unsigned char *map;
 674         struct dso *p, temp_dso = {0};
 675         int fd;
 676         struct stat st;
 677         size_t alloc_size;
 678         int n_th = 0;
 679         int is_self = 0;
 680
 681         if (!*name) {
 682                 errno = EINVAL;
 683                 return 0;
 684         }
 685
 686         /* Catch and block attempts to reload the implementation itself */
 687         if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
 688                 static const char *rp, reserved[] =
 689                         "c\0pthread\0rt\0m\0dl\0util\0xnet\0";
 690                 char *z = strchr(name, '.');
 691                 if (z) {
 692                         size_t l = z-name;
 693                         for (rp=reserved; *rp && strncmp(name+3, rp, l-3); rp+=strlen(rp)+1);
 694                         if (*rp) {
 695                                 if (ldd_mode) {
 696                                         /* Track which names have been resolved
 697                                          * and only report each one once. */
 698                                         static unsigned reported;
 699                                         unsigned mask = 1U<<(rp-reserved);
 700                                         if (!(reported & mask)) {
 701                                                 reported |= mask;
 702                                                 dprintf(1, "\t%s => %s (%p)\n",
 703                                                         name, ldso.name,
 704                                                         ldso.base);
 705                                         }
 706                                 }
 707                                 is_self = 1;
 708                         }
 709                 }
 710         }
 711         if (!strcmp(name, ldso.name)) is_self = 1;
 712         if (is_self) {
 713                 if (!ldso.prev) {
 714                         tail->next = &ldso;
 715                         ldso.prev = tail;
 716                         tail = ldso.next ? ldso.next : &ldso;
 717                 }
 718                 return &ldso;
 719         }
 720         if (strchr(name, '/')) {
 721                 pathname = name;
 722                 fd = open(name, O_RDONLY|O_CLOEXEC);
 723         } else {
 724                 /* Search for the name to see if it's already loaded */
 725                 for (p=head->next; p; p=p->next) {
 726                         if (p->shortname && !strcmp(p->shortname, name)) {
 727                                 p->refcnt++;
 728                                 return p;
 729                         }
 730                 }
 731                 if (strlen(name) > NAME_MAX) return 0;
 732                 fd = -1;
 733                 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
 734                 for (p=needed_by; fd == -1 && p; p=p->needed_by) {
 735                         if (fixup_rpath(p, buf, sizeof buf) < 0)
 736                                 fd = -2; /* Inhibit further search. */
 737                         if (p->rpath)
 738                                 fd = path_open(name, p->rpath, buf, sizeof buf);
 739                 }
 740                 if (fd == -1) {
 741                         if (!sys_path) {
 742                                 char *prefix = 0;
 743                                 size_t prefix_len;
 744                                 if (ldso.name[0]=='/') {
 745                                         char *s, *t, *z;
 746                                         for (s=t=z=ldso.name; *s; s++)
 747                                                 if (*s=='/') z=t, t=s;
 748                                         prefix_len = z-ldso.name;
 749                                         if (prefix_len < PATH_MAX)
 750                                                 prefix = ldso.name;
 751                                 }
 752                                 if (!prefix) {
 753                                         prefix = "";
 754                                         prefix_len = 0;
 755                                 }
 756                                 char etc_ldso_path[prefix_len + 1
 757                                         + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
 758                                 snprintf(etc_ldso_path, sizeof etc_ldso_path,
 759                                         "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
 760                                         (int)prefix_len, prefix);
 761                                 FILE *f = fopen(etc_ldso_path, "rbe");
 762                                 if (f) {
 763                                         if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
 764                                                 free(sys_path);
 765                                                 sys_path = "";
 766                                         }
 767                                         fclose(f);
 768                                 } else if (errno != ENOENT) {
 769                                         sys_path = "";
 770                                 }
 771                         }
 772                         if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
 773                         fd = path_open(name, sys_path, buf, sizeof buf);
 774                 }
 775                 pathname = buf;
 776         }
 777         if (fd < 0) return 0;
 778         if (fstat(fd, &st) < 0) {
 779                 close(fd);
 780                 return 0;
 781         }
 782         for (p=head->next; p; p=p->next) {
 783                 if (p->dev == st.st_dev && p->ino == st.st_ino) {
 784                         /* If this library was previously loaded with a
 785                          * pathname but a search found the same inode,
 786                          * setup its shortname so it can be found by name. */
 787                         if (!p->shortname && pathname != name)
 788                                 p->shortname = strrchr(p->name, '/')+1;
 789                         close(fd);
 790                         p->refcnt++;
 791                         return p;
 792                 }
 793         }
 794         map = noload ? 0 : map_library(fd, &temp_dso);
 795         close(fd);
 796         if (!map) return 0;
 797
 798         /* Allocate storage for the new DSO. When there is TLS, this
 799          * storage must include a reservation for all pre-existing
 800          * threads to obtain copies of both the new TLS, and an
 801          * extended DTV capable of storing an additional slot for
 802          * the newly-loaded DSO. */
 803         alloc_size = sizeof *p + strlen(pathname) + 1;
 804         if (runtime && temp_dso.tls_image) {
 805                 size_t per_th = temp_dso.tls_size + temp_dso.tls_align
 806                         + sizeof(void *) * (tls_cnt+3);
 807                 n_th = libc.threads_minus_1 + 1;
 808                 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
 809                 else alloc_size += n_th * per_th;
 810         }
 811         p = calloc(1, alloc_size);
 812         if (!p) {
 813                 munmap(map, temp_dso.map_len);
 814                 return 0;
 815         }
 816         memcpy(p, &temp_dso, sizeof temp_dso);
 817         decode_dyn(p);
 818         p->dev = st.st_dev;
 819         p->ino = st.st_ino;
 820         p->refcnt = 1;
 821         p->needed_by = needed_by;
 822         p->name = p->buf;
 823         strcpy(p->name, pathname);
 824         /* Add a shortname only if name arg was not an explicit pathname. */
 825         if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
 826         if (p->tls_image) {
 827                 p->tls_id = ++tls_cnt;
 828                 tls_align = MAXP2(tls_align, p->tls_align);
 829 #ifdef TLS_ABOVE_TP
 830                 p->tls_offset = tls_offset + ( (tls_align-1) &
 831                         -(tls_offset + (uintptr_t)p->tls_image) );
 832                 tls_offset += p->tls_size;
 833 #else
 834                 tls_offset += p->tls_size + p->tls_align - 1;
 835                 tls_offset -= (tls_offset + (uintptr_t)p->tls_image)
 836                         & (p->tls_align-1);
 837                 p->tls_offset = tls_offset;
 838 #endif
 839                 p->new_dtv = (void *)(-sizeof(size_t) &
 840                         (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
 841                 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
 842         }
 843
 844         tail->next = p;
 845         p->prev = tail;
 846         tail = p;
 847
 848         if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
 849
 850         return p;
 851 }
 852
 853 static void load_deps(struct dso *p)
 854 {
 855         size_t i, ndeps=0;
 856         struct dso ***deps = &p->deps, **tmp, *dep;
 857         for (; p; p=p->next) {
 858                 for (i=0; p->dynv[i]; i+=2) {
 859                         if (p->dynv[i] != DT_NEEDED) continue;
 860                         dep = load_library(p->strings + p->dynv[i+1], p);
 861                         if (!dep) {
 862                                 error("Error loading shared library %s: %m (needed by %s)",
 863                                         p->strings + p->dynv[i+1], p->name);
 864                                 if (runtime) longjmp(*rtld_fail, 1);
 865                                 continue;
 866                         }
 867                         if (runtime) {
 868                                 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
 869                                 if (!tmp) longjmp(*rtld_fail, 1);
 870                                 tmp[ndeps++] = dep;
 871                                 tmp[ndeps] = 0;
 872                                 *deps = tmp;
 873                         }
 874                 }
 875         }
 876 }
 877
 878 static void load_preload(char *s)
 879 {
 880         int tmp;
 881         char *z;
 882         for (z=s; *z; s=z) {
 883                 for (   ; *s && (isspace(*s) || *s==':'); s++);
 884                 for (z=s; *z && !isspace(*z) && *z!=':'; z++);
 885                 tmp = *z;
 886                 *z = 0;
 887                 load_library(s, 0);
 888                 *z = tmp;
 889         }
 890 }
 891
 892 static void make_global(struct dso *p)
 893 {
 894         for (; p; p=p->next) p->global = 1;
 895 }
 896
 897 static void do_mips_relocs(struct dso *p, size_t *got)
 898 {
 899         size_t i, j, rel[2];
 900         unsigned char *base = p->base;
 901         i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
 902         if (p==&ldso) {
 903                 got += i;
 904         } else {
 905                 while (i--) *got++ += (size_t)base;
 906         }
 907         j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
 908         i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
 909         Sym *sym = p->syms + j;
 910         rel[0] = (unsigned char *)got - base;
 911         for (i-=j; i; i--, sym++, rel[0]+=sizeof(size_t)) {
 912                 rel[1] = sym-p->syms << 8 | R_MIPS_JUMP_SLOT;
 913                 do_relocs(p, rel, sizeof rel, 2);
 914         }
 915 }
 916
 917 static void reloc_all(struct dso *p)
 918 {
 919         size_t dyn[DYN_CNT];
 920         for (; p; p=p->next) {
 921                 if (p->relocated) continue;
 922                 decode_vec(p->dynv, dyn, DYN_CNT);
 923                 if (NEED_MIPS_GOT_RELOCS)
 924                         do_mips_relocs(p, (void *)(p->base+dyn[DT_PLTGOT]));
 925                 do_relocs(p, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
 926                         2+(dyn[DT_PLTREL]==DT_RELA));
 927                 do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2);
 928                 do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
 929
 930                 if (head != &ldso && p->relro_start != p->relro_end &&
 931                     mprotect(p->base+p->relro_start, p->relro_end-p->relro_start, PROT_READ)
 932                     && errno != ENOSYS) {
 933                         error("Error relocating %s: RELRO protection failed: %m",
 934                                 p->name);
 935                         if (runtime) longjmp(*rtld_fail, 1);
 936                 }
 937
 938                 p->relocated = 1;
 939         }
 940 }
 941
 942 static void kernel_mapped_dso(struct dso *p)
 943 {
 944         size_t min_addr = -1, max_addr = 0, cnt;
 945         Phdr *ph = p->phdr;
 946         for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
 947                 if (ph->p_type == PT_DYNAMIC) {
 948                         p->dynv = (void *)(p->base + ph->p_vaddr);
 949                 } else if (ph->p_type == PT_GNU_RELRO) {
 950                         p->relro_start = ph->p_vaddr & -PAGE_SIZE;
 951                         p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
 952                 }
 953                 if (ph->p_type != PT_LOAD) continue;
 954                 if (ph->p_vaddr < min_addr)
 955                         min_addr = ph->p_vaddr;
 956                 if (ph->p_vaddr+ph->p_memsz > max_addr)
 957                         max_addr = ph->p_vaddr+ph->p_memsz;
 958         }
 959         min_addr &= -PAGE_SIZE;
 960         max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
 961         p->map = p->base + min_addr;
 962         p->map_len = max_addr - min_addr;
 963         p->kernel_mapped = 1;
 964 }
 965
 966 static void do_fini()
 967 {
 968         struct dso *p;
 969         size_t dyn[DYN_CNT];
 970         for (p=fini_head; p; p=p->fini_next) {
 971                 if (!p->constructed) continue;
 972                 decode_vec(p->dynv, dyn, DYN_CNT);
 973                 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
 974                         size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
 975                         size_t *fn = (size_t *)(p->base + dyn[DT_FINI_ARRAY])+n;
 976                         while (n--) ((void (*)(void))*--fn)();
 977                 }
 978 #ifndef NO_LEGACY_INITFINI
 979                 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
 980                         ((void (*)(void))(p->base + dyn[DT_FINI]))();
 981 #endif
 982         }
 983 }
 984
 985 static void do_init_fini(struct dso *p)
 986 {
 987         size_t dyn[DYN_CNT];
 988         int need_locking = libc.threads_minus_1;
 989         /* Allow recursive calls that arise when a library calls
 990          * dlopen from one of its constructors, but block any
 991          * other threads until all ctors have finished. */
 992         if (need_locking) pthread_mutex_lock(&init_fini_lock);
 993         for (; p; p=p->prev) {
 994                 if (p->constructed) continue;
 995                 p->constructed = 1;
 996                 decode_vec(p->dynv, dyn, DYN_CNT);
 997                 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
 998                         p->fini_next = fini_head;
 999                         fini_head = p;
1000                 }
1001 #ifndef NO_LEGACY_INITFINI
1002                 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
1003                         ((void (*)(void))(p->base + dyn[DT_INIT]))();
1004 #endif
1005                 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
1006                         size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
1007                         size_t *fn = (void *)(p->base + dyn[DT_INIT_ARRAY]);
1008                         while (n--) ((void (*)(void))*fn++)();
1009                 }
1010                 if (!need_locking && libc.threads_minus_1) {
1011                         need_locking = 1;
1012                         pthread_mutex_lock(&init_fini_lock);
1013                 }
1014         }
1015         if (need_locking) pthread_mutex_unlock(&init_fini_lock);
1016 }
1017
1018 static void dl_debug_state(void)
1019 {
1020 }
1021
1022 weak_alias(dl_debug_state, _dl_debug_state);
1023
1024 void __reset_tls()
1025 {
1026         pthread_t self = __pthread_self();
1027         struct dso *p;
1028         for (p=head; p; p=p->next) {
1029                 if (!p->tls_id || !self->dtv[p->tls_id]) continue;
1030                 memcpy(self->dtv[p->tls_id], p->tls_image, p->tls_len);
1031                 memset((char *)self->dtv[p->tls_id]+p->tls_len, 0,
1032                         p->tls_size - p->tls_len);
1033                 if (p->tls_id == (size_t)self->dtv[0]) break;
1034         }
1035 }
1036
1037 void *__copy_tls(unsigned char *mem)
1038 {
1039         pthread_t td;
1040         struct dso *p;
1041         void **dtv;
1042
1043 #ifdef TLS_ABOVE_TP
1044         dtv = (void **)(mem + libc.tls_size) - (tls_cnt + 1);
1045
1046         mem += -((uintptr_t)mem + sizeof(struct pthread)) & (tls_align-1);
1047         td = (pthread_t)mem;
1048         mem += sizeof(struct pthread);
1049
1050         for (p=head; p; p=p->next) {
1051                 if (!p->tls_id) continue;
1052                 dtv[p->tls_id] = mem + p->tls_offset;
1053                 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
1054         }
1055 #else
1056         dtv = (void **)mem;
1057
1058         mem += libc.tls_size - sizeof(struct pthread);
1059         mem -= (uintptr_t)mem & (tls_align-1);
1060         td = (pthread_t)mem;
1061
1062         for (p=head; p; p=p->next) {
1063                 if (!p->tls_id) continue;
1064                 dtv[p->tls_id] = mem - p->tls_offset;
1065                 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
1066         }
1067 #endif
1068         dtv[0] = (void *)tls_cnt;
1069         td->dtv = td->dtv_copy = dtv;
1070         return td;
1071 }
1072
1073 __attribute__((__visibility__("hidden")))
1074 void *__tls_get_new(size_t *v)
1075 {
1076         pthread_t self = __pthread_self();
1077
1078         /* Block signals to make accessing new TLS async-signal-safe */
1079         sigset_t set;
1080         __block_all_sigs(&set);
1081         if (v[0]<=(size_t)self->dtv[0]) {
1082                 __restore_sigs(&set);
1083                 return (char *)self->dtv[v[0]]+v[1];
1084         }
1085
1086         /* This is safe without any locks held because, if the caller
1087          * is able to request the Nth entry of the DTV, the DSO list
1088          * must be valid at least that far out and it was synchronized
1089          * at program startup or by an already-completed call to dlopen. */
1090         struct dso *p;
1091         for (p=head; p->tls_id != v[0]; p=p->next);
1092
1093         /* Get new DTV space from new DSO if needed */
1094         if (v[0] > (size_t)self->dtv[0]) {
1095                 void **newdtv = p->new_dtv +
1096                         (v[0]+1)*sizeof(void *)*a_fetch_add(&p->new_dtv_idx,1);
1097                 memcpy(newdtv, self->dtv,
1098                         ((size_t)self->dtv[0]+1) * sizeof(void *));
1099                 newdtv[0] = (void *)v[0];
1100                 self->dtv = self->dtv_copy = newdtv;
1101         }
1102
1103         /* Get new TLS memory from all new DSOs up to the requested one */
1104         unsigned char *mem;
1105         for (p=head; ; p=p->next) {
1106                 if (!p->tls_id || self->dtv[p->tls_id]) continue;
1107                 mem = p->new_tls + (p->tls_size + p->tls_align)
1108                         * a_fetch_add(&p->new_tls_idx,1);
1109                 mem += ((uintptr_t)p->tls_image - (uintptr_t)mem)
1110                         & (p->tls_align-1);
1111                 self->dtv[p->tls_id] = mem;
1112                 memcpy(mem, p->tls_image, p->tls_len);
1113                 if (p->tls_id == v[0]) break;
1114         }
1115         __restore_sigs(&set);
1116         return mem + v[1];
1117 }
1118
1119 static void update_tls_size()
1120 {
1121         libc.tls_size = ALIGN(
1122                 (1+tls_cnt) * sizeof(void *) +
1123                 tls_offset +
1124                 sizeof(struct pthread) +
1125                 tls_align * 2,
1126         tls_align);
1127 }
1128
1129 /* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
1130  * following stage 2 and stage 3 functions via primitive symbolic lookup
1131  * since it does not have access to their addresses to begin with. */
1132
1133 /* Stage 2 of the dynamic linker is called after relative relocations
1134  * have been processed. It can make function calls to static functions
1135  * and access string literals and static data, but cannot use extern
1136  * symbols. Its job is to perform symbolic relocations on the dynamic
1137  * linker itself, but some of the relocations performed may need to be
1138  * replaced later due to copy relocations in the main program. */
1139
1140 void __dls2(unsigned char *base, size_t *sp)
1141 {
1142         Ehdr *ehdr = (void *)base;
1143         ldso.base = base;
1144         ldso.name = ldso.shortname = "libc.so";
1145         ldso.global = 1;
1146         ldso.phnum = ehdr->e_phnum;
1147         ldso.phdr = (void *)(base + ehdr->e_phoff);
1148         ldso.phentsize = ehdr->e_phentsize;
1149         kernel_mapped_dso(&ldso);
1150         decode_dyn(&ldso);
1151
1152         /* Prepare storage for to save clobbered REL addends so they
1153          * can be reused in stage 3. There should be very few. If
1154          * something goes wrong and there are a huge number, abort
1155          * instead of risking stack overflow. */
1156         size_t dyn[DYN_CNT];
1157         decode_vec(ldso.dynv, dyn, DYN_CNT);
1158         size_t *rel = (void *)(base+dyn[DT_REL]);
1159         size_t rel_size = dyn[DT_RELSZ];
1160         size_t symbolic_rel_cnt = 0;
1161         apply_addends_to = rel;
1162         for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t))
1163                 if (!IS_RELATIVE(rel[1])) symbolic_rel_cnt++;
1164         if (symbolic_rel_cnt >= ADDEND_LIMIT) a_crash();
1165         size_t addends[symbolic_rel_cnt+1];
1166         saved_addends = addends;
1167
1168         head = &ldso;
1169         reloc_all(&ldso);
1170
1171         ldso.relocated = 0;
1172
1173         /* Call dynamic linker stage-3, __dls3, looking it up
1174          * symbolically as a barrier against moving the address
1175          * load across the above relocation processing. */
1176         struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
1177         ((stage3_func)(ldso.base+dls3_def.sym->st_value))(sp);
1178 }
1179
1180 /* Stage 3 of the dynamic linker is called with the dynamic linker/libc
1181  * fully functional. Its job is to load (if not already loaded) and
1182  * process dependencies and relocations for the main application and
1183  * transfer control to its entry point. */
1184
1185 _Noreturn void __dls3(size_t *sp)
1186 {
1187         static struct dso app, vdso;
1188         size_t aux[AUX_CNT], *auxv;
1189         size_t i;
1190         char *env_preload=0;
1191         size_t vdso_base;
1192         int argc = *sp;
1193         char **argv = (void *)(sp+1);
1194         char **argv_orig = argv;
1195         char **envp = argv+argc+1;
1196
1197         /* Find aux vector just past environ[] and use it to initialize
1198          * global data that may be needed before we can make syscalls. */
1199         __environ = envp;
1200         for (i=argc+1; argv[i]; i++);
1201         libc.auxv = auxv = (void *)(argv+i+1);
1202         decode_vec(auxv, aux, AUX_CNT);
1203         __hwcap = aux[AT_HWCAP];
1204         libc.page_size = aux[AT_PAGESZ];
1205         libc.secure = ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1206                 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]);
1207
1208         /* Setup early thread pointer in builtin_tls for ldso/libc itself to
1209          * use during dynamic linking. If possible it will also serve as the
1210          * thread pointer at runtime. */
1211         libc.tls_size = sizeof builtin_tls;
1212         if (__init_tp(__copy_tls((void *)builtin_tls)) < 0) {
1213                 a_crash();
1214         }
1215
1216         /* Only trust user/env if kernel says we're not suid/sgid */
1217         if (!libc.secure) {
1218                 env_path = getenv("LD_LIBRARY_PATH");
1219                 env_preload = getenv("LD_PRELOAD");
1220         }
1221
1222         /* If the main program was already loaded by the kernel,
1223          * AT_PHDR will point to some location other than the dynamic
1224          * linker's program headers. */
1225         if (aux[AT_PHDR] != (size_t)ldso.phdr) {
1226                 size_t interp_off = 0;
1227                 size_t tls_image = 0;
1228                 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1229                 Phdr *phdr = app.phdr = (void *)aux[AT_PHDR];
1230                 app.phnum = aux[AT_PHNUM];
1231                 app.phentsize = aux[AT_PHENT];
1232                 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1233                         if (phdr->p_type == PT_PHDR)
1234                                 app.base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1235                         else if (phdr->p_type == PT_INTERP)
1236                                 interp_off = (size_t)phdr->p_vaddr;
1237                         else if (phdr->p_type == PT_TLS) {
1238                                 tls_image = phdr->p_vaddr;
1239                                 app.tls_len = phdr->p_filesz;
1240                                 app.tls_size = phdr->p_memsz;
1241                                 app.tls_align = phdr->p_align;
1242                         }
1243                 }
1244                 if (app.tls_size) app.tls_image = (char *)app.base + tls_image;
1245                 if (interp_off) ldso.name = (char *)app.base + interp_off;
1246                 if ((aux[0] & (1UL<<AT_EXECFN))
1247                     && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1248                         app.name = (char *)aux[AT_EXECFN];
1249                 else
1250                         app.name = argv[0];
1251                 kernel_mapped_dso(&app);
1252         } else {
1253                 int fd;
1254                 char *ldname = argv[0];
1255                 size_t l = strlen(ldname);
1256                 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1257                 argv++;
1258                 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1259                         char *opt = argv[0]+2;
1260                         *argv++ = (void *)-1;
1261                         if (!*opt) {
1262                                 break;
1263                         } else if (!memcmp(opt, "list", 5)) {
1264                                 ldd_mode = 1;
1265                         } else if (!memcmp(opt, "library-path", 12)) {
1266                                 if (opt[12]=='=') env_path = opt+13;
1267                                 else if (opt[12]) *argv = 0;
1268                                 else if (*argv) env_path = *argv++;
1269                         } else if (!memcmp(opt, "preload", 7)) {
1270                                 if (opt[7]=='=') env_preload = opt+8;
1271                                 else if (opt[7]) *argv = 0;
1272                                 else if (*argv) env_preload = *argv++;
1273                         } else {
1274                                 argv[0] = 0;
1275                         }
1276                 }
1277                 argv[-1] = (void *)(argc - (argv-argv_orig));
1278                 if (!argv[0]) {
1279                         dprintf(2, "musl libc\n"
1280                                 "Version %s\n"
1281                                 "Dynamic Program Loader\n"
1282                                 "Usage: %s [options] [--] pathname%s\n",
1283                                 __libc_get_version(), ldname,
1284                                 ldd_mode ? "" : " [args]");
1285                         _exit(1);
1286                 }
1287                 fd = open(argv[0], O_RDONLY);
1288                 if (fd < 0) {
1289                         dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1290                         _exit(1);
1291                 }
1292                 runtime = 1;
1293                 Ehdr *ehdr = (void *)map_library(fd, &app);
1294                 if (!ehdr) {
1295                         dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1296                         _exit(1);
1297                 }
1298                 runtime = 0;
1299                 close(fd);
1300                 ldso.name = ldname;
1301                 app.name = argv[0];
1302                 aux[AT_ENTRY] = (size_t)app.base + ehdr->e_entry;
1303                 /* Find the name that would have been used for the dynamic
1304                  * linker had ldd not taken its place. */
1305                 if (ldd_mode) {
1306                         for (i=0; i<app.phnum; i++) {
1307                                 if (app.phdr[i].p_type == PT_INTERP)
1308                                         ldso.name = (void *)(app.base
1309                                                 + app.phdr[i].p_vaddr);
1310                         }
1311                         dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
1312                 }
1313         }
1314         if (app.tls_size) {
1315                 app.tls_id = tls_cnt = 1;
1316 #ifdef TLS_ABOVE_TP
1317                 app.tls_offset = 0;
1318                 tls_offset = app.tls_size
1319                         + ( -((uintptr_t)app.tls_image + app.tls_size)
1320                         & (app.tls_align-1) );
1321 #else
1322                 tls_offset = app.tls_offset = app.tls_size
1323                         + ( -((uintptr_t)app.tls_image + app.tls_size)
1324                         & (app.tls_align-1) );
1325 #endif
1326                 tls_align = MAXP2(tls_align, app.tls_align);
1327         }
1328         app.global = 1;
1329         decode_dyn(&app);
1330
1331         /* Attach to vdso, if provided by the kernel */
1332         if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
1333                 Ehdr *ehdr = (void *)vdso_base;
1334                 Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
1335                 vdso.phnum = ehdr->e_phnum;
1336                 vdso.phentsize = ehdr->e_phentsize;
1337                 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1338                         if (phdr->p_type == PT_DYNAMIC)
1339                                 vdso.dynv = (void *)(vdso_base + phdr->p_offset);
1340                         if (phdr->p_type == PT_LOAD)
1341                                 vdso.base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1342                 }
1343                 vdso.name = "";
1344                 vdso.shortname = "linux-gate.so.1";
1345                 vdso.global = 1;
1346                 vdso.relocated = 1;
1347                 decode_dyn(&vdso);
1348                 vdso.prev = &ldso;
1349                 ldso.next = &vdso;
1350         }
1351
1352         /* Initial dso chain consists only of the app. */
1353         head = tail = &app;
1354
1355         /* Donate unused parts of app and library mapping to malloc */
1356         reclaim_gaps(&app);
1357         reclaim_gaps(&ldso);
1358
1359         /* Load preload/needed libraries, add their symbols to the global
1360          * namespace, and perform all remaining relocations. */
1361         if (env_preload) load_preload(env_preload);
1362         load_deps(&app);
1363         make_global(&app);
1364
1365 #ifndef DYNAMIC_IS_RO
1366         for (i=0; app.dynv[i]; i+=2)
1367                 if (app.dynv[i]==DT_DEBUG)
1368                         app.dynv[i+1] = (size_t)&debug;
1369 #endif
1370
1371         /* The main program must be relocated LAST since it may contin
1372          * copy relocations which depend on libraries' relocations. */
1373         reloc_all(app.next);
1374         reloc_all(&app);
1375
1376         update_tls_size();
1377         if (libc.tls_size > sizeof builtin_tls || tls_align > MIN_TLS_ALIGN) {
1378                 void *initial_tls = calloc(libc.tls_size, 1);
1379                 if (!initial_tls) {
1380                         dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1381                                 argv[0], libc.tls_size);
1382                         _exit(127);
1383                 }
1384                 if (__init_tp(__copy_tls(initial_tls)) < 0) {
1385                         a_crash();
1386                 }
1387         } else {
1388                 size_t tmp_tls_size = libc.tls_size;
1389                 pthread_t self = __pthread_self();
1390                 /* Temporarily set the tls size to the full size of
1391                  * builtin_tls so that __copy_tls will use the same layout
1392                  * as it did for before. Then check, just to be safe. */
1393                 libc.tls_size = sizeof builtin_tls;
1394                 if (__copy_tls((void*)builtin_tls) != self) a_crash();
1395                 libc.tls_size = tmp_tls_size;
1396         }
1397         static_tls_cnt = tls_cnt;
1398
1399         if (ldso_fail) _exit(127);
1400         if (ldd_mode) _exit(0);
1401
1402         /* Switch to runtime mode: any further failures in the dynamic
1403          * linker are a reportable failure rather than a fatal startup
1404          * error. */
1405         runtime = 1;
1406
1407         debug.ver = 1;
1408         debug.bp = dl_debug_state;
1409         debug.head = head;
1410         debug.base = ldso.base;
1411         debug.state = 0;
1412         _dl_debug_state();
1413
1414         __init_libc(envp, argv[0]);
1415         atexit(do_fini);
1416         errno = 0;
1417         do_init_fini(tail);
1418
1419         CRTJMP((void *)aux[AT_ENTRY], argv-1);
1420         for(;;);
1421 }
1422
1423 void *dlopen(const char *file, int mode)
1424 {
1425         struct dso *volatile p, *orig_tail, *next;
1426         size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1427         size_t i;
1428         int cs;
1429         jmp_buf jb;
1430
1431         if (!file) return head;
1432
1433         pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1434         pthread_rwlock_wrlock(&lock);
1435         __inhibit_ptc();
1436
1437         p = 0;
1438         orig_tls_cnt = tls_cnt;
1439         orig_tls_offset = tls_offset;
1440         orig_tls_align = tls_align;
1441         orig_tail = tail;
1442         noload = mode & RTLD_NOLOAD;
1443
1444         rtld_fail = &jb;
1445         if (setjmp(*rtld_fail)) {
1446                 /* Clean up anything new that was (partially) loaded */
1447                 if (p && p->deps) for (i=0; p->deps[i]; i++)
1448                         if (p->deps[i]->global < 0)
1449                                 p->deps[i]->global = 0;
1450                 for (p=orig_tail->next; p; p=next) {
1451                         next = p->next;
1452                         munmap(p->map, p->map_len);
1453                         while (p->td_index) {
1454                                 void *tmp = p->td_index->next;
1455                                 free(p->td_index);
1456                                 p->td_index = tmp;
1457                         }
1458                         if (p->rpath != p->rpath_orig)
1459                                 free(p->rpath);
1460                         free(p->deps);
1461                         free(p);
1462                 }
1463                 tls_cnt = orig_tls_cnt;
1464                 tls_offset = orig_tls_offset;
1465                 tls_align = orig_tls_align;
1466                 tail = orig_tail;
1467                 tail->next = 0;
1468                 p = 0;
1469                 goto end;
1470         } else p = load_library(file, head);
1471
1472         if (!p) {
1473                 error(noload ?
1474                         "Library %s is not already loaded" :
1475                         "Error loading shared library %s: %m",
1476                         file);
1477                 goto end;
1478         }
1479
1480         /* First load handling */
1481         if (!p->deps) {
1482                 load_deps(p);
1483                 if (p->deps) for (i=0; p->deps[i]; i++)
1484                         if (!p->deps[i]->global)
1485                                 p->deps[i]->global = -1;
1486                 if (!p->global) p->global = -1;
1487                 reloc_all(p);
1488                 if (p->deps) for (i=0; p->deps[i]; i++)
1489                         if (p->deps[i]->global < 0)
1490                                 p->deps[i]->global = 0;
1491                 if (p->global < 0) p->global = 0;
1492         }
1493
1494         if (mode & RTLD_GLOBAL) {
1495                 if (p->deps) for (i=0; p->deps[i]; i++)
1496                         p->deps[i]->global = 1;
1497                 p->global = 1;
1498         }
1499
1500         update_tls_size();
1501         _dl_debug_state();
1502         orig_tail = tail;
1503 end:
1504         __release_ptc();
1505         if (p) gencnt++;
1506         pthread_rwlock_unlock(&lock);
1507         if (p) do_init_fini(orig_tail);
1508         pthread_setcancelstate(cs, 0);
1509         return p;
1510 }
1511
1512 static int invalid_dso_handle(void *h)
1513 {
1514         struct dso *p;
1515         for (p=head; p; p=p->next) if (h==p) return 0;
1516         error("Invalid library handle %p", (void *)h);
1517         return 1;
1518 }
1519
1520 void *__tls_get_addr(size_t *);
1521
1522 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1523 {
1524         size_t i;
1525         uint32_t h = 0, gh = 0;
1526         Sym *sym;
1527         if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1528                 if (p == RTLD_DEFAULT) {
1529                         p = head;
1530                 } else if (p == RTLD_NEXT) {
1531                         for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
1532                         if (!p) p=head;
1533                         p = p->next;
1534                 }
1535                 struct symdef def = find_sym(p, s, 0);
1536                 if (!def.sym) goto failed;
1537                 if ((def.sym->st_info&0xf) == STT_TLS)
1538                         return __tls_get_addr((size_t []){def.dso->tls_id, def.sym->st_value});
1539                 return def.dso->base + def.sym->st_value;
1540         }
1541         if (invalid_dso_handle(p))
1542                 return 0;
1543         if (p->ghashtab) {
1544                 gh = gnu_hash(s);
1545                 sym = gnu_lookup(s, gh, p);
1546         } else {
1547                 h = sysv_hash(s);
1548                 sym = sysv_lookup(s, h, p);
1549         }
1550         if (sym && (sym->st_info&0xf) == STT_TLS)
1551                 return __tls_get_addr((size_t []){p->tls_id, sym->st_value});
1552         if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1553                 return p->base + sym->st_value;
1554         if (p->deps) for (i=0; p->deps[i]; i++) {
1555                 if (p->deps[i]->ghashtab) {
1556                         if (!gh) gh = gnu_hash(s);
1557                         sym = gnu_lookup(s, gh, p->deps[i]);
1558                 } else {
1559                         if (!h) h = sysv_hash(s);
1560                         sym = sysv_lookup(s, h, p->deps[i]);
1561                 }
1562                 if (sym && (sym->st_info&0xf) == STT_TLS)
1563                         return __tls_get_addr((size_t []){p->deps[i]->tls_id, sym->st_value});
1564                 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1565                         return p->deps[i]->base + sym->st_value;
1566         }
1567 failed:
1568         error("Symbol not found: %s", s);
1569         return 0;
1570 }
1571
1572 int __dladdr(const void *addr, Dl_info *info)
1573 {
1574         struct dso *p;
1575         Sym *sym;
1576         uint32_t nsym;
1577         char *strings;
1578         size_t i;
1579         void *best = 0;
1580         char *bestname;
1581
1582         pthread_rwlock_rdlock(&lock);
1583         for (p=head; p && (unsigned char *)addr-p->map>p->map_len; p=p->next);
1584         pthread_rwlock_unlock(&lock);
1585
1586         if (!p) return 0;
1587
1588         sym = p->syms;
1589         strings = p->strings;
1590         if (p->hashtab) {
1591                 nsym = p->hashtab[1];
1592         } else {
1593                 uint32_t *buckets;
1594                 uint32_t *hashval;
1595                 buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
1596                 sym += p->ghashtab[1];
1597                 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
1598                         if (buckets[i] > nsym)
1599                                 nsym = buckets[i];
1600                 }
1601                 if (nsym) {
1602                         nsym -= p->ghashtab[1];
1603                         hashval = buckets + p->ghashtab[0] + nsym;
1604                         do nsym++;
1605                         while (!(*hashval++ & 1));
1606                 }
1607         }
1608
1609         for (; nsym; nsym--, sym++) {
1610                 if (sym->st_value
1611                  && (1<<(sym->st_info&0xf) & OK_TYPES)
1612                  && (1<<(sym->st_info>>4) & OK_BINDS)) {
1613                         void *symaddr = p->base + sym->st_value;
1614                         if (symaddr > addr || symaddr < best)
1615                                 continue;
1616                         best = symaddr;
1617                         bestname = strings + sym->st_name;
1618                         if (addr == symaddr)
1619                                 break;
1620                 }
1621         }
1622
1623         if (!best) return 0;
1624
1625         info->dli_fname = p->name;
1626         info->dli_fbase = p->base;
1627         info->dli_sname = bestname;
1628         info->dli_saddr = best;
1629
1630         return 1;
1631 }
1632
1633 __attribute__((__visibility__("hidden")))
1634 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1635 {
1636         void *res;
1637         pthread_rwlock_rdlock(&lock);
1638         res = do_dlsym(p, s, ra);
1639         pthread_rwlock_unlock(&lock);
1640         return res;
1641 }
1642
1643 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
1644 {
1645         struct dso *current;
1646         struct dl_phdr_info info;
1647         int ret = 0;
1648         for(current = head; current;) {
1649                 info.dlpi_addr      = (uintptr_t)current->base;
1650                 info.dlpi_name      = current->name;
1651                 info.dlpi_phdr      = current->phdr;
1652                 info.dlpi_phnum     = current->phnum;
1653                 info.dlpi_adds      = gencnt;
1654                 info.dlpi_subs      = 0;
1655                 info.dlpi_tls_modid = current->tls_id;
1656                 info.dlpi_tls_data  = current->tls_image;
1657
1658                 ret = (callback)(&info, sizeof (info), data);
1659
1660                 if (ret != 0) break;
1661
1662                 pthread_rwlock_rdlock(&lock);
1663                 current = current->next;
1664                 pthread_rwlock_unlock(&lock);
1665         }
1666         return ret;
1667 }
1668 #else
1669 static int invalid_dso_handle(void *h)
1670 {
1671         error("Invalid library handle %p", (void *)h);
1672         return 1;
1673 }
1674 void *dlopen(const char *file, int mode)
1675 {
1676         error("Dynamic loading not supported");
1677         return 0;
1678 }
1679 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1680 {
1681         error("Symbol not found: %s", s);
1682         return 0;
1683 }
1684 int __dladdr (const void *addr, Dl_info *info)
1685 {
1686         return 0;
1687 }
1688 #endif
1689
1690 int __dlinfo(void *dso, int req, void *res)
1691 {
1692         if (invalid_dso_handle(dso)) return -1;
1693         if (req != RTLD_DI_LINKMAP) {
1694                 error("Unsupported request %d", req);
1695                 return -1;
1696         }
1697         *(struct link_map **)res = dso;
1698         return 0;
1699 }
1700
1701 char *dlerror()
1702 {
1703         pthread_t self = __pthread_self();
1704         if (!self->dlerror_flag) return 0;
1705         self->dlerror_flag = 0;
1706         char *s = self->dlerror_buf;
1707         if (s == (void *)-1)
1708                 return "Dynamic linker failed to allocate memory for error message";
1709         else
1710                 return s;
1711 }
1712
1713 int dlclose(void *p)
1714 {
1715         return invalid_dso_handle(p);
1716 }
1717
1718 void __dl_thread_cleanup(void)
1719 {
1720         pthread_t self = __pthread_self();
1721         if (self->dlerror_buf != (void *)-1)
1722                 free(self->dlerror_buf);
1723 }
1724
1725 static void error(const char *fmt, ...)
1726 {
1727         va_list ap;
1728         va_start(ap, fmt);
1729 #ifdef SHARED
1730         if (!runtime) {
1731                 vdprintf(2, fmt, ap);
1732                 dprintf(2, "\n");
1733                 ldso_fail = 1;
1734                 va_end(ap);
1735                 return;
1736         }
1737 #endif
1738         pthread_t self = __pthread_self();
1739         if (self->dlerror_buf != (void *)-1)
1740                 free(self->dlerror_buf);
1741         size_t len = vsnprintf(0, 0, fmt, ap);
1742         va_end(ap);
1743         char *buf = malloc(len+1);
1744         if (buf) {
1745                 va_start(ap, fmt);
1746                 vsnprintf(buf, len+1, fmt, ap);
1747                 va_end(ap);
1748         } else {
1749                 buf = (void *)-1;
1750         }
1751         self->dlerror_buf = buf;
1752         self->dlerror_flag = 1;
1753 }