nsz Git - musl/blob - 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) < 0)
 540                                 goto error;
 541                         break;
 542                 }
 543         dso->map = map;
 544         dso->map_len = map_len;
 545         dso->base = base;
 546         dso->dynv = (void *)(base+dyn);
 547         if (dso->tls_size) dso->tls_image = (void *)(base+tls_image);
 548         if (!runtime) reclaim_gaps(dso);
 549         free(allocated_buf);
 550         return map;
 551 noexec:
 552         errno = ENOEXEC;
 553 error:
 554         if (map!=MAP_FAILED) munmap(map, map_len);
 555         free(allocated_buf);
 556         return 0;
 557 }
 558
 559 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
 560 {
 561         size_t l;
 562         int fd;
 563         for (;;) {
 564                 s += strspn(s, ":\n");
 565                 l = strcspn(s, ":\n");
 566                 if (l-1 >= INT_MAX) return -1;
 567                 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
 568                         if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
 569                         switch (errno) {
 570                         case ENOENT:
 571                         case ENOTDIR:
 572                         case EACCES:
 573                         case ENAMETOOLONG:
 574                                 break;
 575                         default:
 576                                 /* Any negative value but -1 will inhibit
 577                                  * futher path search. */
 578                                 return -2;
 579                         }
 580                 }
 581                 s += l;
 582         }
 583 }
 584
 585 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
 586 {
 587         size_t n, l;
 588         const char *s, *t, *origin;
 589         char *d;
 590         if (p->rpath || !p->rpath_orig) return 0;
 591         if (!strchr(p->rpath_orig, '$')) {
 592                 p->rpath = p->rpath_orig;
 593                 return 0;
 594         }
 595         n = 0;
 596         s = p->rpath_orig;
 597         while ((t=strchr(s, '$'))) {
 598                 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
 599                         return 0;
 600                 s = t+1;
 601                 n++;
 602         }
 603         if (n > SSIZE_MAX/PATH_MAX) return 0;
 604
 605         if (p->kernel_mapped) {
 606                 /* $ORIGIN searches cannot be performed for the main program
 607                  * when it is suid/sgid/AT_SECURE. This is because the
 608                  * pathname is under the control of the caller of execve.
 609                  * For libraries, however, $ORIGIN can be processed safely
 610                  * since the library's pathname came from a trusted source
 611                  * (either system paths or a call to dlopen). */
 612                 if (libc.secure)
 613                         return 0;
 614                 l = readlink("/proc/self/exe", buf, buf_size);
 615                 if (l == -1) switch (errno) {
 616                 case ENOENT:
 617                 case ENOTDIR:
 618                 case EACCES:
 619                         break;
 620                 default:
 621                         return -1;
 622                 }
 623                 if (l >= buf_size)
 624                         return 0;
 625                 buf[l] = 0;
 626                 origin = buf;
 627         } else {
 628                 origin = p->name;
 629         }
 630         t = strrchr(origin, '/');
 631         l = t ? t-origin : 0;
 632         p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
 633         if (!p->rpath) return -1;
 634
 635         d = p->rpath;
 636         s = p->rpath_orig;
 637         while ((t=strchr(s, '$'))) {
 638                 memcpy(d, s, t-s);
 639                 d += t-s;
 640                 memcpy(d, origin, l);
 641                 d += l;
 642                 /* It was determined previously that the '$' is followed
 643                  * either by "ORIGIN" or "{ORIGIN}". */
 644                 s = t + 7 + 2*(t[1]=='{');
 645         }
 646         strcpy(d, s);
 647         return 0;
 648 }
 649
 650 static void decode_dyn(struct dso *p)
 651 {
 652         size_t dyn[DYN_CNT];
 653         decode_vec(p->dynv, dyn, DYN_CNT);
 654         p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
 655         p->strings = (void *)(p->base + dyn[DT_STRTAB]);
 656         if (dyn[0]&(1<<DT_HASH))
 657                 p->hashtab = (void *)(p->base + dyn[DT_HASH]);
 658         if (dyn[0]&(1<<DT_RPATH))
 659                 p->rpath_orig = (void *)(p->strings + dyn[DT_RPATH]);
 660         if (dyn[0]&(1<<DT_RUNPATH))
 661                 p->rpath_orig = (void *)(p->strings + dyn[DT_RUNPATH]);
 662         if (search_vec(p->dynv, dyn, DT_GNU_HASH))
 663                 p->ghashtab = (void *)(p->base + *dyn);
 664         if (search_vec(p->dynv, dyn, DT_VERSYM))
 665                 p->versym = (void *)(p->base + *dyn);
 666 }
 667
 668 static struct dso *load_library(const char *name, struct dso *needed_by)
 669 {
 670         char buf[2*NAME_MAX+2];
 671         const char *pathname;
 672         unsigned char *map;
 673         struct dso *p, temp_dso = {0};
 674         int fd;
 675         struct stat st;
 676         size_t alloc_size;
 677         int n_th = 0;
 678         int is_self = 0;
 679
 680         if (!*name) {
 681                 errno = EINVAL;
 682                 return 0;
 683         }
 684
 685         /* Catch and block attempts to reload the implementation itself */
 686         if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
 687                 static const char *rp, reserved[] =
 688                         "c\0pthread\0rt\0m\0dl\0util\0xnet\0";
 689                 char *z = strchr(name, '.');
 690                 if (z) {
 691                         size_t l = z-name;
 692                         for (rp=reserved; *rp && strncmp(name+3, rp, l-3); rp+=strlen(rp)+1);
 693                         if (*rp) {
 694                                 if (ldd_mode) {
 695                                         /* Track which names have been resolved
 696                                          * and only report each one once. */
 697                                         static unsigned reported;
 698                                         unsigned mask = 1U<<(rp-reserved);
 699                                         if (!(reported & mask)) {
 700                                                 reported |= mask;
 701                                                 dprintf(1, "\t%s => %s (%p)\n",
 702                                                         name, ldso.name,
 703                                                         ldso.base);
 704                                         }
 705                                 }
 706                                 is_self = 1;
 707                         }
 708                 }
 709         }
 710         if (!strcmp(name, ldso.name)) is_self = 1;
 711         if (is_self) {
 712                 if (!ldso.prev) {
 713                         tail->next = &ldso;
 714                         ldso.prev = tail;
 715                         tail = ldso.next ? ldso.next : &ldso;
 716                 }
 717                 return &ldso;
 718         }
 719         if (strchr(name, '/')) {
 720                 pathname = name;
 721                 fd = open(name, O_RDONLY|O_CLOEXEC);
 722         } else {
 723                 /* Search for the name to see if it's already loaded */
 724                 for (p=head->next; p; p=p->next) {
 725                         if (p->shortname && !strcmp(p->shortname, name)) {
 726                                 p->refcnt++;
 727                                 return p;
 728                         }
 729                 }
 730                 if (strlen(name) > NAME_MAX) return 0;
 731                 fd = -1;
 732                 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
 733                 for (p=needed_by; fd == -1 && p; p=p->needed_by) {
 734                         if (fixup_rpath(p, buf, sizeof buf) < 0)
 735                                 fd = -2; /* Inhibit further search. */
 736                         if (p->rpath)
 737                                 fd = path_open(name, p->rpath, buf, sizeof buf);
 738                 }
 739                 if (fd == -1) {
 740                         if (!sys_path) {
 741                                 char *prefix = 0;
 742                                 size_t prefix_len;
 743                                 if (ldso.name[0]=='/') {
 744                                         char *s, *t, *z;
 745                                         for (s=t=z=ldso.name; *s; s++)
 746                                                 if (*s=='/') z=t, t=s;
 747                                         prefix_len = z-ldso.name;
 748                                         if (prefix_len < PATH_MAX)
 749                                                 prefix = ldso.name;
 750                                 }
 751                                 if (!prefix) {
 752                                         prefix = "";
 753                                         prefix_len = 0;
 754                                 }
 755                                 char etc_ldso_path[prefix_len + 1
 756                                         + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
 757                                 snprintf(etc_ldso_path, sizeof etc_ldso_path,
 758                                         "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
 759                                         (int)prefix_len, prefix);
 760                                 FILE *f = fopen(etc_ldso_path, "rbe");
 761                                 if (f) {
 762                                         if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
 763                                                 free(sys_path);
 764                                                 sys_path = "";
 765                                         }
 766                                         fclose(f);
 767                                 } else if (errno != ENOENT) {
 768                                         sys_path = "";
 769                                 }
 770                         }
 771                         if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
 772                         fd = path_open(name, sys_path, buf, sizeof buf);
 773                 }
 774                 pathname = buf;
 775         }
 776         if (fd < 0) return 0;
 777         if (fstat(fd, &st) < 0) {
 778                 close(fd);
 779                 return 0;
 780         }
 781         for (p=head->next; p; p=p->next) {
 782                 if (p->dev == st.st_dev && p->ino == st.st_ino) {
 783                         /* If this library was previously loaded with a
 784                          * pathname but a search found the same inode,
 785                          * setup its shortname so it can be found by name. */
 786                         if (!p->shortname && pathname != name)
 787                                 p->shortname = strrchr(p->name, '/')+1;
 788                         close(fd);
 789                         p->refcnt++;
 790                         return p;
 791                 }
 792         }
 793         map = noload ? 0 : map_library(fd, &temp_dso);
 794         close(fd);
 795         if (!map) return 0;
 796
 797         /* Allocate storage for the new DSO. When there is TLS, this
 798          * storage must include a reservation for all pre-existing
 799          * threads to obtain copies of both the new TLS, and an
 800          * extended DTV capable of storing an additional slot for
 801          * the newly-loaded DSO. */
 802         alloc_size = sizeof *p + strlen(pathname) + 1;
 803         if (runtime && temp_dso.tls_image) {
 804                 size_t per_th = temp_dso.tls_size + temp_dso.tls_align
 805                         + sizeof(void *) * (tls_cnt+3);
 806                 n_th = libc.threads_minus_1 + 1;
 807                 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
 808                 else alloc_size += n_th * per_th;
 809         }
 810         p = calloc(1, alloc_size);
 811         if (!p) {
 812                 munmap(map, temp_dso.map_len);
 813                 return 0;
 814         }
 815         memcpy(p, &temp_dso, sizeof temp_dso);
 816         decode_dyn(p);
 817         p->dev = st.st_dev;
 818         p->ino = st.st_ino;
 819         p->refcnt = 1;
 820         p->needed_by = needed_by;
 821         p->name = p->buf;
 822         strcpy(p->name, pathname);
 823         /* Add a shortname only if name arg was not an explicit pathname. */
 824         if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
 825         if (p->tls_image) {
 826                 p->tls_id = ++tls_cnt;
 827                 tls_align = MAXP2(tls_align, p->tls_align);
 828 #ifdef TLS_ABOVE_TP
 829                 p->tls_offset = tls_offset + ( (tls_align-1) &
 830                         -(tls_offset + (uintptr_t)p->tls_image) );
 831                 tls_offset += p->tls_size;
 832 #else
 833                 tls_offset += p->tls_size + p->tls_align - 1;
 834                 tls_offset -= (tls_offset + (uintptr_t)p->tls_image)
 835                         & (p->tls_align-1);
 836                 p->tls_offset = tls_offset;
 837 #endif
 838                 p->new_dtv = (void *)(-sizeof(size_t) &
 839                         (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
 840                 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
 841         }
 842
 843         tail->next = p;
 844         p->prev = tail;
 845         tail = p;
 846
 847         if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
 848
 849         return p;
 850 }
 851
 852 static void load_deps(struct dso *p)
 853 {
 854         size_t i, ndeps=0;
 855         struct dso ***deps = &p->deps, **tmp, *dep;
 856         for (; p; p=p->next) {
 857                 for (i=0; p->dynv[i]; i+=2) {
 858                         if (p->dynv[i] != DT_NEEDED) continue;
 859                         dep = load_library(p->strings + p->dynv[i+1], p);
 860                         if (!dep) {
 861                                 error("Error loading shared library %s: %m (needed by %s)",
 862                                         p->strings + p->dynv[i+1], p->name);
 863                                 if (runtime) longjmp(*rtld_fail, 1);
 864                                 continue;
 865                         }
 866                         if (runtime) {
 867                                 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
 868                                 if (!tmp) longjmp(*rtld_fail, 1);
 869                                 tmp[ndeps++] = dep;
 870                                 tmp[ndeps] = 0;
 871                                 *deps = tmp;
 872                         }
 873                 }
 874         }
 875 }
 876
 877 static void load_preload(char *s)
 878 {
 879         int tmp;
 880         char *z;
 881         for (z=s; *z; s=z) {
 882                 for (   ; *s && (isspace(*s) || *s==':'); s++);
 883                 for (z=s; *z && !isspace(*z) && *z!=':'; z++);
 884                 tmp = *z;
 885                 *z = 0;
 886                 load_library(s, 0);
 887                 *z = tmp;
 888         }
 889 }
 890
 891 static void make_global(struct dso *p)
 892 {
 893         for (; p; p=p->next) p->global = 1;
 894 }
 895
 896 static void do_mips_relocs(struct dso *p, size_t *got)
 897 {
 898         size_t i, j, rel[2];
 899         unsigned char *base = p->base;
 900         i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
 901         if (p==&ldso) {
 902                 got += i;
 903         } else {
 904                 while (i--) *got++ += (size_t)base;
 905         }
 906         j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
 907         i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
 908         Sym *sym = p->syms + j;
 909         rel[0] = (unsigned char *)got - base;
 910         for (i-=j; i; i--, sym++, rel[0]+=sizeof(size_t)) {
 911                 rel[1] = sym-p->syms << 8 | R_MIPS_JUMP_SLOT;
 912                 do_relocs(p, rel, sizeof rel, 2);
 913         }
 914 }
 915
 916 static void reloc_all(struct dso *p)
 917 {
 918         size_t dyn[DYN_CNT];
 919         for (; p; p=p->next) {
 920                 if (p->relocated) continue;
 921                 decode_vec(p->dynv, dyn, DYN_CNT);
 922                 if (NEED_MIPS_GOT_RELOCS)
 923                         do_mips_relocs(p, (void *)(p->base+dyn[DT_PLTGOT]));
 924                 do_relocs(p, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
 925                         2+(dyn[DT_PLTREL]==DT_RELA));
 926                 do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2);
 927                 do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
 928
 929                 if (head != &ldso && p->relro_start != p->relro_end &&
 930                     mprotect(p->base+p->relro_start, p->relro_end-p->relro_start, PROT_READ) < 0) {
 931                         error("Error relocating %s: RELRO protection failed: %m",
 932                                 p->name);
 933                         if (runtime) longjmp(*rtld_fail, 1);
 934                 }
 935
 936                 p->relocated = 1;
 937         }
 938 }
 939
 940 static void kernel_mapped_dso(struct dso *p)
 941 {
 942         size_t min_addr = -1, max_addr = 0, cnt;
 943         Phdr *ph = p->phdr;
 944         for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
 945                 if (ph->p_type == PT_DYNAMIC) {
 946                         p->dynv = (void *)(p->base + ph->p_vaddr);
 947                 } else if (ph->p_type == PT_GNU_RELRO) {
 948                         p->relro_start = ph->p_vaddr & -PAGE_SIZE;
 949                         p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
 950                 }
 951                 if (ph->p_type != PT_LOAD) continue;
 952                 if (ph->p_vaddr < min_addr)
 953                         min_addr = ph->p_vaddr;
 954                 if (ph->p_vaddr+ph->p_memsz > max_addr)
 955                         max_addr = ph->p_vaddr+ph->p_memsz;
 956         }
 957         min_addr &= -PAGE_SIZE;
 958         max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
 959         p->map = p->base + min_addr;
 960         p->map_len = max_addr - min_addr;
 961         p->kernel_mapped = 1;
 962 }
 963
 964 static void do_fini()
 965 {
 966         struct dso *p;
 967         size_t dyn[DYN_CNT];
 968         for (p=fini_head; p; p=p->fini_next) {
 969                 if (!p->constructed) continue;
 970                 decode_vec(p->dynv, dyn, DYN_CNT);
 971                 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
 972                         size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
 973                         size_t *fn = (size_t *)(p->base + dyn[DT_FINI_ARRAY])+n;
 974                         while (n--) ((void (*)(void))*--fn)();
 975                 }
 976 #ifndef NO_LEGACY_INITFINI
 977                 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
 978                         ((void (*)(void))(p->base + dyn[DT_FINI]))();
 979 #endif
 980         }
 981 }
 982
 983 static void do_init_fini(struct dso *p)
 984 {
 985         size_t dyn[DYN_CNT];
 986         int need_locking = libc.threads_minus_1;
 987         /* Allow recursive calls that arise when a library calls
 988          * dlopen from one of its constructors, but block any
 989          * other threads until all ctors have finished. */
 990         if (need_locking) pthread_mutex_lock(&init_fini_lock);
 991         for (; p; p=p->prev) {
 992                 if (p->constructed) continue;
 993                 p->constructed = 1;
 994                 decode_vec(p->dynv, dyn, DYN_CNT);
 995                 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
 996                         p->fini_next = fini_head;
 997                         fini_head = p;
 998                 }
 999 #ifndef NO_LEGACY_INITFINI
1000                 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
1001                         ((void (*)(void))(p->base + dyn[DT_INIT]))();
1002 #endif
1003                 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
1004                         size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
1005                         size_t *fn = (void *)(p->base + dyn[DT_INIT_ARRAY]);
1006                         while (n--) ((void (*)(void))*fn++)();
1007                 }
1008                 if (!need_locking && libc.threads_minus_1) {
1009                         need_locking = 1;
1010                         pthread_mutex_lock(&init_fini_lock);
1011                 }
1012         }
1013         if (need_locking) pthread_mutex_unlock(&init_fini_lock);
1014 }
1015
1016 static void dl_debug_state(void)
1017 {
1018 }
1019
1020 weak_alias(dl_debug_state, _dl_debug_state);
1021
1022 void __reset_tls()
1023 {
1024         pthread_t self = __pthread_self();
1025         struct dso *p;
1026         for (p=head; p; p=p->next) {
1027                 if (!p->tls_id || !self->dtv[p->tls_id]) continue;
1028                 memcpy(self->dtv[p->tls_id], p->tls_image, p->tls_len);
1029                 memset((char *)self->dtv[p->tls_id]+p->tls_len, 0,
1030                         p->tls_size - p->tls_len);
1031                 if (p->tls_id == (size_t)self->dtv[0]) break;
1032         }
1033 }
1034
1035 void *__copy_tls(unsigned char *mem)
1036 {
1037         pthread_t td;
1038         struct dso *p;
1039         void **dtv;
1040
1041 #ifdef TLS_ABOVE_TP
1042         dtv = (void **)(mem + libc.tls_size) - (tls_cnt + 1);
1043
1044         mem += -((uintptr_t)mem + sizeof(struct pthread)) & (tls_align-1);
1045         td = (pthread_t)mem;
1046         mem += sizeof(struct pthread);
1047
1048         for (p=head; p; p=p->next) {
1049                 if (!p->tls_id) continue;
1050                 dtv[p->tls_id] = mem + p->tls_offset;
1051                 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
1052         }
1053 #else
1054         dtv = (void **)mem;
1055
1056         mem += libc.tls_size - sizeof(struct pthread);
1057         mem -= (uintptr_t)mem & (tls_align-1);
1058         td = (pthread_t)mem;
1059
1060         for (p=head; p; p=p->next) {
1061                 if (!p->tls_id) continue;
1062                 dtv[p->tls_id] = mem - p->tls_offset;
1063                 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
1064         }
1065 #endif
1066         dtv[0] = (void *)tls_cnt;
1067         td->dtv = td->dtv_copy = dtv;
1068         return td;
1069 }
1070
1071 __attribute__((__visibility__("hidden")))
1072 void *__tls_get_new(size_t *v)
1073 {
1074         pthread_t self = __pthread_self();
1075
1076         /* Block signals to make accessing new TLS async-signal-safe */
1077         sigset_t set;
1078         __block_all_sigs(&set);
1079         if (v[0]<=(size_t)self->dtv[0]) {
1080                 __restore_sigs(&set);
1081                 return (char *)self->dtv[v[0]]+v[1];
1082         }
1083
1084         /* This is safe without any locks held because, if the caller
1085          * is able to request the Nth entry of the DTV, the DSO list
1086          * must be valid at least that far out and it was synchronized
1087          * at program startup or by an already-completed call to dlopen. */
1088         struct dso *p;
1089         for (p=head; p->tls_id != v[0]; p=p->next);
1090
1091         /* Get new DTV space from new DSO if needed */
1092         if (v[0] > (size_t)self->dtv[0]) {
1093                 void **newdtv = p->new_dtv +
1094                         (v[0]+1)*sizeof(void *)*a_fetch_add(&p->new_dtv_idx,1);
1095                 memcpy(newdtv, self->dtv,
1096                         ((size_t)self->dtv[0]+1) * sizeof(void *));
1097                 newdtv[0] = (void *)v[0];
1098                 self->dtv = self->dtv_copy = newdtv;
1099         }
1100
1101         /* Get new TLS memory from all new DSOs up to the requested one */
1102         unsigned char *mem;
1103         for (p=head; ; p=p->next) {
1104                 if (!p->tls_id || self->dtv[p->tls_id]) continue;
1105                 mem = p->new_tls + (p->tls_size + p->tls_align)
1106                         * a_fetch_add(&p->new_tls_idx,1);
1107                 mem += ((uintptr_t)p->tls_image - (uintptr_t)mem)
1108                         & (p->tls_align-1);
1109                 self->dtv[p->tls_id] = mem;
1110                 memcpy(mem, p->tls_image, p->tls_len);
1111                 if (p->tls_id == v[0]) break;
1112         }
1113         __restore_sigs(&set);
1114         return mem + v[1];
1115 }
1116
1117 static void update_tls_size()
1118 {
1119         libc.tls_size = ALIGN(
1120                 (1+tls_cnt) * sizeof(void *) +
1121                 tls_offset +
1122                 sizeof(struct pthread) +
1123                 tls_align * 2,
1124         tls_align);
1125 }
1126
1127 /* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
1128  * following stage 2 and stage 3 functions via primitive symbolic lookup
1129  * since it does not have access to their addresses to begin with. */
1130
1131 /* Stage 2 of the dynamic linker is called after relative relocations
1132  * have been processed. It can make function calls to static functions
1133  * and access string literals and static data, but cannot use extern
1134  * symbols. Its job is to perform symbolic relocations on the dynamic
1135  * linker itself, but some of the relocations performed may need to be
1136  * replaced later due to copy relocations in the main program. */
1137
1138 void __dls2(unsigned char *base, size_t *sp)
1139 {
1140         Ehdr *ehdr = (void *)base;
1141         ldso.base = base;
1142         ldso.name = ldso.shortname = "libc.so";
1143         ldso.global = 1;
1144         ldso.phnum = ehdr->e_phnum;
1145         ldso.phdr = (void *)(base + ehdr->e_phoff);
1146         ldso.phentsize = ehdr->e_phentsize;
1147         kernel_mapped_dso(&ldso);
1148         decode_dyn(&ldso);
1149
1150         /* Prepare storage for to save clobbered REL addends so they
1151          * can be reused in stage 3. There should be very few. If
1152          * something goes wrong and there are a huge number, abort
1153          * instead of risking stack overflow. */
1154         size_t dyn[DYN_CNT];
1155         decode_vec(ldso.dynv, dyn, DYN_CNT);
1156         size_t *rel = (void *)(base+dyn[DT_REL]);
1157         size_t rel_size = dyn[DT_RELSZ];
1158         size_t symbolic_rel_cnt = 0;
1159         apply_addends_to = rel;
1160         for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t))
1161                 if (!IS_RELATIVE(rel[1])) symbolic_rel_cnt++;
1162         if (symbolic_rel_cnt >= ADDEND_LIMIT) a_crash();
1163         size_t addends[symbolic_rel_cnt+1];
1164         saved_addends = addends;
1165
1166         head = &ldso;
1167         reloc_all(&ldso);
1168
1169         ldso.relocated = 0;
1170
1171         /* Call dynamic linker stage-3, __dls3, looking it up
1172          * symbolically as a barrier against moving the address
1173          * load across the above relocation processing. */
1174         struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
1175         ((stage3_func)(ldso.base+dls3_def.sym->st_value))(sp);
1176 }
1177
1178 /* Stage 3 of the dynamic linker is called with the dynamic linker/libc
1179  * fully functional. Its job is to load (if not already loaded) and
1180  * process dependencies and relocations for the main application and
1181  * transfer control to its entry point. */
1182
1183 _Noreturn void __dls3(size_t *sp)
1184 {
1185         static struct dso app, vdso;
1186         size_t aux[AUX_CNT], *auxv;
1187         size_t i;
1188         char *env_preload=0;
1189         size_t vdso_base;
1190         int argc = *sp;
1191         char **argv = (void *)(sp+1);
1192         char **argv_orig = argv;
1193         char **envp = argv+argc+1;
1194
1195         /* Find aux vector just past environ[] and use it to initialize
1196          * global data that may be needed before we can make syscalls. */
1197         __environ = envp;
1198         for (i=argc+1; argv[i]; i++);
1199         libc.auxv = auxv = (void *)(argv+i+1);
1200         decode_vec(auxv, aux, AUX_CNT);
1201         __hwcap = aux[AT_HWCAP];
1202         libc.page_size = aux[AT_PAGESZ];
1203         libc.secure = ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1204                 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]);
1205
1206         /* Setup early thread pointer in builtin_tls for ldso/libc itself to
1207          * use during dynamic linking. If possible it will also serve as the
1208          * thread pointer at runtime. */
1209         libc.tls_size = sizeof builtin_tls;
1210         if (__init_tp(__copy_tls((void *)builtin_tls)) < 0) {
1211                 a_crash();
1212         }
1213
1214         /* Only trust user/env if kernel says we're not suid/sgid */
1215         if (!libc.secure) {
1216                 env_path = getenv("LD_LIBRARY_PATH");
1217                 env_preload = getenv("LD_PRELOAD");
1218         }
1219
1220         /* If the main program was already loaded by the kernel,
1221          * AT_PHDR will point to some location other than the dynamic
1222          * linker's program headers. */
1223         if (aux[AT_PHDR] != (size_t)ldso.phdr) {
1224                 size_t interp_off = 0;
1225                 size_t tls_image = 0;
1226                 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1227                 Phdr *phdr = app.phdr = (void *)aux[AT_PHDR];
1228                 app.phnum = aux[AT_PHNUM];
1229                 app.phentsize = aux[AT_PHENT];
1230                 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1231                         if (phdr->p_type == PT_PHDR)
1232                                 app.base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1233                         else if (phdr->p_type == PT_INTERP)
1234                                 interp_off = (size_t)phdr->p_vaddr;
1235                         else if (phdr->p_type == PT_TLS) {
1236                                 tls_image = phdr->p_vaddr;
1237                                 app.tls_len = phdr->p_filesz;
1238                                 app.tls_size = phdr->p_memsz;
1239                                 app.tls_align = phdr->p_align;
1240                         }
1241                 }
1242                 if (app.tls_size) app.tls_image = (char *)app.base + tls_image;
1243                 if (interp_off) ldso.name = (char *)app.base + interp_off;
1244                 if ((aux[0] & (1UL<<AT_EXECFN))
1245                     && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1246                         app.name = (char *)aux[AT_EXECFN];
1247                 else
1248                         app.name = argv[0];
1249                 kernel_mapped_dso(&app);
1250         } else {
1251                 int fd;
1252                 char *ldname = argv[0];
1253                 size_t l = strlen(ldname);
1254                 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1255                 argv++;
1256                 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1257                         char *opt = argv[0]+2;
1258                         *argv++ = (void *)-1;
1259                         if (!*opt) {
1260                                 break;
1261                         } else if (!memcmp(opt, "list", 5)) {
1262                                 ldd_mode = 1;
1263                         } else if (!memcmp(opt, "library-path", 12)) {
1264                                 if (opt[12]=='=') env_path = opt+13;
1265                                 else if (opt[12]) *argv = 0;
1266                                 else if (*argv) env_path = *argv++;
1267                         } else if (!memcmp(opt, "preload", 7)) {
1268                                 if (opt[7]=='=') env_preload = opt+8;
1269                                 else if (opt[7]) *argv = 0;
1270                                 else if (*argv) env_preload = *argv++;
1271                         } else {
1272                                 argv[0] = 0;
1273                         }
1274                 }
1275                 argv[-1] = (void *)(argc - (argv-argv_orig));
1276                 if (!argv[0]) {
1277                         dprintf(2, "musl libc\n"
1278                                 "Version %s\n"
1279                                 "Dynamic Program Loader\n"
1280                                 "Usage: %s [options] [--] pathname%s\n",
1281                                 __libc_get_version(), ldname,
1282                                 ldd_mode ? "" : " [args]");
1283                         _exit(1);
1284                 }
1285                 fd = open(argv[0], O_RDONLY);
1286                 if (fd < 0) {
1287                         dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1288                         _exit(1);
1289                 }
1290                 runtime = 1;
1291                 Ehdr *ehdr = (void *)map_library(fd, &app);
1292                 if (!ehdr) {
1293                         dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1294                         _exit(1);
1295                 }
1296                 runtime = 0;
1297                 close(fd);
1298                 ldso.name = ldname;
1299                 app.name = argv[0];
1300                 aux[AT_ENTRY] = (size_t)app.base + ehdr->e_entry;
1301                 /* Find the name that would have been used for the dynamic
1302                  * linker had ldd not taken its place. */
1303                 if (ldd_mode) {
1304                         for (i=0; i<app.phnum; i++) {
1305                                 if (app.phdr[i].p_type == PT_INTERP)
1306                                         ldso.name = (void *)(app.base
1307                                                 + app.phdr[i].p_vaddr);
1308                         }
1309                         dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
1310                 }
1311         }
1312         if (app.tls_size) {
1313                 app.tls_id = tls_cnt = 1;
1314 #ifdef TLS_ABOVE_TP
1315                 app.tls_offset = 0;
1316                 tls_offset = app.tls_size
1317                         + ( -((uintptr_t)app.tls_image + app.tls_size)
1318                         & (app.tls_align-1) );
1319 #else
1320                 tls_offset = app.tls_offset = app.tls_size
1321                         + ( -((uintptr_t)app.tls_image + app.tls_size)
1322                         & (app.tls_align-1) );
1323 #endif
1324                 tls_align = MAXP2(tls_align, app.tls_align);
1325         }
1326         app.global = 1;
1327         decode_dyn(&app);
1328
1329         /* Attach to vdso, if provided by the kernel */
1330         if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
1331                 Ehdr *ehdr = (void *)vdso_base;
1332                 Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
1333                 vdso.phnum = ehdr->e_phnum;
1334                 vdso.phentsize = ehdr->e_phentsize;
1335                 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1336                         if (phdr->p_type == PT_DYNAMIC)
1337                                 vdso.dynv = (void *)(vdso_base + phdr->p_offset);
1338                         if (phdr->p_type == PT_LOAD)
1339                                 vdso.base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1340                 }
1341                 vdso.name = "";
1342                 vdso.shortname = "linux-gate.so.1";
1343                 vdso.global = 1;
1344                 vdso.relocated = 1;
1345                 decode_dyn(&vdso);
1346                 vdso.prev = &ldso;
1347                 ldso.next = &vdso;
1348         }
1349
1350         /* Initial dso chain consists only of the app. */
1351         head = tail = &app;
1352
1353         /* Donate unused parts of app and library mapping to malloc */
1354         reclaim_gaps(&app);
1355         reclaim_gaps(&ldso);
1356
1357         /* Load preload/needed libraries, add their symbols to the global
1358          * namespace, and perform all remaining relocations. */
1359         if (env_preload) load_preload(env_preload);
1360         load_deps(&app);
1361         make_global(&app);
1362
1363 #ifndef DYNAMIC_IS_RO
1364         for (i=0; app.dynv[i]; i+=2)
1365                 if (app.dynv[i]==DT_DEBUG)
1366                         app.dynv[i+1] = (size_t)&debug;
1367 #endif
1368
1369         /* The main program must be relocated LAST since it may contin
1370          * copy relocations which depend on libraries' relocations. */
1371         reloc_all(app.next);
1372         reloc_all(&app);
1373
1374         update_tls_size();
1375         if (libc.tls_size > sizeof builtin_tls || tls_align > MIN_TLS_ALIGN) {
1376                 void *initial_tls = calloc(libc.tls_size, 1);
1377                 if (!initial_tls) {
1378                         dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1379                                 argv[0], libc.tls_size);
1380                         _exit(127);
1381                 }
1382                 if (__init_tp(__copy_tls(initial_tls)) < 0) {
1383                         a_crash();
1384                 }
1385         } else {
1386                 size_t tmp_tls_size = libc.tls_size;
1387                 pthread_t self = __pthread_self();
1388                 /* Temporarily set the tls size to the full size of
1389                  * builtin_tls so that __copy_tls will use the same layout
1390                  * as it did for before. Then check, just to be safe. */
1391                 libc.tls_size = sizeof builtin_tls;
1392                 if (__copy_tls((void*)builtin_tls) != self) a_crash();
1393                 libc.tls_size = tmp_tls_size;
1394         }
1395         static_tls_cnt = tls_cnt;
1396
1397         if (ldso_fail) _exit(127);
1398         if (ldd_mode) _exit(0);
1399
1400         /* Switch to runtime mode: any further failures in the dynamic
1401          * linker are a reportable failure rather than a fatal startup
1402          * error. */
1403         runtime = 1;
1404
1405         debug.ver = 1;
1406         debug.bp = dl_debug_state;
1407         debug.head = head;
1408         debug.base = ldso.base;
1409         debug.state = 0;
1410         _dl_debug_state();
1411
1412         __init_libc(envp, argv[0]);
1413         atexit(do_fini);
1414         errno = 0;
1415         do_init_fini(tail);
1416
1417         CRTJMP((void *)aux[AT_ENTRY], argv-1);
1418         for(;;);
1419 }
1420
1421 void *dlopen(const char *file, int mode)
1422 {
1423         struct dso *volatile p, *orig_tail, *next;
1424         size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1425         size_t i;
1426         int cs;
1427         jmp_buf jb;
1428
1429         if (!file) return head;
1430
1431         pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1432         pthread_rwlock_wrlock(&lock);
1433         __inhibit_ptc();
1434
1435         p = 0;
1436         orig_tls_cnt = tls_cnt;
1437         orig_tls_offset = tls_offset;
1438         orig_tls_align = tls_align;
1439         orig_tail = tail;
1440         noload = mode & RTLD_NOLOAD;
1441
1442         rtld_fail = &jb;
1443         if (setjmp(*rtld_fail)) {
1444                 /* Clean up anything new that was (partially) loaded */
1445                 if (p && p->deps) for (i=0; p->deps[i]; i++)
1446                         if (p->deps[i]->global < 0)
1447                                 p->deps[i]->global = 0;
1448                 for (p=orig_tail->next; p; p=next) {
1449                         next = p->next;
1450                         munmap(p->map, p->map_len);
1451                         while (p->td_index) {
1452                                 void *tmp = p->td_index->next;
1453                                 free(p->td_index);
1454                                 p->td_index = tmp;
1455                         }
1456                         if (p->rpath != p->rpath_orig)
1457                                 free(p->rpath);
1458                         free(p->deps);
1459                         free(p);
1460                 }
1461                 tls_cnt = orig_tls_cnt;
1462                 tls_offset = orig_tls_offset;
1463                 tls_align = orig_tls_align;
1464                 tail = orig_tail;
1465                 tail->next = 0;
1466                 p = 0;
1467                 goto end;
1468         } else p = load_library(file, head);
1469
1470         if (!p) {
1471                 error(noload ?
1472                         "Library %s is not already loaded" :
1473                         "Error loading shared library %s: %m",
1474                         file);
1475                 goto end;
1476         }
1477
1478         /* First load handling */
1479         if (!p->deps) {
1480                 load_deps(p);
1481                 if (p->deps) for (i=0; p->deps[i]; i++)
1482                         if (!p->deps[i]->global)
1483                                 p->deps[i]->global = -1;
1484                 if (!p->global) p->global = -1;
1485                 reloc_all(p);
1486                 if (p->deps) for (i=0; p->deps[i]; i++)
1487                         if (p->deps[i]->global < 0)
1488                                 p->deps[i]->global = 0;
1489                 if (p->global < 0) p->global = 0;
1490         }
1491
1492         if (mode & RTLD_GLOBAL) {
1493                 if (p->deps) for (i=0; p->deps[i]; i++)
1494                         p->deps[i]->global = 1;
1495                 p->global = 1;
1496         }
1497
1498         update_tls_size();
1499         _dl_debug_state();
1500         orig_tail = tail;
1501 end:
1502         __release_ptc();
1503         if (p) gencnt++;
1504         pthread_rwlock_unlock(&lock);
1505         if (p) do_init_fini(orig_tail);
1506         pthread_setcancelstate(cs, 0);
1507         return p;
1508 }
1509
1510 static int invalid_dso_handle(void *h)
1511 {
1512         struct dso *p;
1513         for (p=head; p; p=p->next) if (h==p) return 0;
1514         error("Invalid library handle %p", (void *)h);
1515         return 1;
1516 }
1517
1518 void *__tls_get_addr(size_t *);
1519
1520 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1521 {
1522         size_t i;
1523         uint32_t h = 0, gh = 0;
1524         Sym *sym;
1525         if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1526                 if (p == RTLD_DEFAULT) {
1527                         p = head;
1528                 } else if (p == RTLD_NEXT) {
1529                         for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
1530                         if (!p) p=head;
1531                         p = p->next;
1532                 }
1533                 struct symdef def = find_sym(p, s, 0);
1534                 if (!def.sym) goto failed;
1535                 if ((def.sym->st_info&0xf) == STT_TLS)
1536                         return __tls_get_addr((size_t []){def.dso->tls_id, def.sym->st_value});
1537                 return def.dso->base + def.sym->st_value;
1538         }
1539         if (invalid_dso_handle(p))
1540                 return 0;
1541         if (p->ghashtab) {
1542                 gh = gnu_hash(s);
1543                 sym = gnu_lookup(s, gh, p);
1544         } else {
1545                 h = sysv_hash(s);
1546                 sym = sysv_lookup(s, h, p);
1547         }
1548         if (sym && (sym->st_info&0xf) == STT_TLS)
1549                 return __tls_get_addr((size_t []){p->tls_id, sym->st_value});
1550         if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1551                 return p->base + sym->st_value;
1552         if (p->deps) for (i=0; p->deps[i]; i++) {
1553                 if (p->deps[i]->ghashtab) {
1554                         if (!gh) gh = gnu_hash(s);
1555                         sym = gnu_lookup(s, gh, p->deps[i]);
1556                 } else {
1557                         if (!h) h = sysv_hash(s);
1558                         sym = sysv_lookup(s, h, p->deps[i]);
1559                 }
1560                 if (sym && (sym->st_info&0xf) == STT_TLS)
1561                         return __tls_get_addr((size_t []){p->deps[i]->tls_id, sym->st_value});
1562                 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1563                         return p->deps[i]->base + sym->st_value;
1564         }
1565 failed:
1566         error("Symbol not found: %s", s);
1567         return 0;
1568 }
1569
1570 int __dladdr(const void *addr, Dl_info *info)
1571 {
1572         struct dso *p;
1573         Sym *sym;
1574         uint32_t nsym;
1575         char *strings;
1576         size_t i;
1577         void *best = 0;
1578         char *bestname;
1579
1580         pthread_rwlock_rdlock(&lock);
1581         for (p=head; p && (unsigned char *)addr-p->map>p->map_len; p=p->next);
1582         pthread_rwlock_unlock(&lock);
1583
1584         if (!p) return 0;
1585
1586         sym = p->syms;
1587         strings = p->strings;
1588         if (p->hashtab) {
1589                 nsym = p->hashtab[1];
1590         } else {
1591                 uint32_t *buckets;
1592                 uint32_t *hashval;
1593                 buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
1594                 sym += p->ghashtab[1];
1595                 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
1596                         if (buckets[i] > nsym)
1597                                 nsym = buckets[i];
1598                 }
1599                 if (nsym) {
1600                         nsym -= p->ghashtab[1];
1601                         hashval = buckets + p->ghashtab[0] + nsym;
1602                         do nsym++;
1603                         while (!(*hashval++ & 1));
1604                 }
1605         }
1606
1607         for (; nsym; nsym--, sym++) {
1608                 if (sym->st_value
1609                  && (1<<(sym->st_info&0xf) & OK_TYPES)
1610                  && (1<<(sym->st_info>>4) & OK_BINDS)) {
1611                         void *symaddr = p->base + sym->st_value;
1612                         if (symaddr > addr || symaddr < best)
1613                                 continue;
1614                         best = symaddr;
1615                         bestname = strings + sym->st_name;
1616                         if (addr == symaddr)
1617                                 break;
1618                 }
1619         }
1620
1621         if (!best) return 0;
1622
1623         info->dli_fname = p->name;
1624         info->dli_fbase = p->base;
1625         info->dli_sname = bestname;
1626         info->dli_saddr = best;
1627
1628         return 1;
1629 }
1630
1631 __attribute__((__visibility__("hidden")))
1632 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1633 {
1634         void *res;
1635         pthread_rwlock_rdlock(&lock);
1636         res = do_dlsym(p, s, ra);
1637         pthread_rwlock_unlock(&lock);
1638         return res;
1639 }
1640
1641 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
1642 {
1643         struct dso *current;
1644         struct dl_phdr_info info;
1645         int ret = 0;
1646         for(current = head; current;) {
1647                 info.dlpi_addr      = (uintptr_t)current->base;
1648                 info.dlpi_name      = current->name;
1649                 info.dlpi_phdr      = current->phdr;
1650                 info.dlpi_phnum     = current->phnum;
1651                 info.dlpi_adds      = gencnt;
1652                 info.dlpi_subs      = 0;
1653                 info.dlpi_tls_modid = current->tls_id;
1654                 info.dlpi_tls_data  = current->tls_image;
1655
1656                 ret = (callback)(&info, sizeof (info), data);
1657
1658                 if (ret != 0) break;
1659
1660                 pthread_rwlock_rdlock(&lock);
1661                 current = current->next;
1662                 pthread_rwlock_unlock(&lock);
1663         }
1664         return ret;
1665 }
1666 #else
1667 static int invalid_dso_handle(void *h)
1668 {
1669         error("Invalid library handle %p", (void *)h);
1670         return 1;
1671 }
1672 void *dlopen(const char *file, int mode)
1673 {
1674         error("Dynamic loading not supported");
1675         return 0;
1676 }
1677 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1678 {
1679         error("Symbol not found: %s", s);
1680         return 0;
1681 }
1682 int __dladdr (const void *addr, Dl_info *info)
1683 {
1684         return 0;
1685 }
1686 #endif
1687
1688 int __dlinfo(void *dso, int req, void *res)
1689 {
1690         if (invalid_dso_handle(dso)) return -1;
1691         if (req != RTLD_DI_LINKMAP) {
1692                 error("Unsupported request %d", req);
1693                 return -1;
1694         }
1695         *(struct link_map **)res = dso;
1696         return 0;
1697 }
1698
1699 char *dlerror()
1700 {
1701         pthread_t self = __pthread_self();
1702         if (!self->dlerror_flag) return 0;
1703         self->dlerror_flag = 0;
1704         char *s = self->dlerror_buf;
1705         if (s == (void *)-1)
1706                 return "Dynamic linker failed to allocate memory for error message";
1707         else
1708                 return s;
1709 }
1710
1711 int dlclose(void *p)
1712 {
1713         return invalid_dso_handle(p);
1714 }
1715
1716 void __dl_thread_cleanup(void)
1717 {
1718         pthread_t self = __pthread_self();
1719         if (self->dlerror_buf != (void *)-1)
1720                 free(self->dlerror_buf);
1721 }
1722
1723 static void error(const char *fmt, ...)
1724 {
1725         va_list ap;
1726         va_start(ap, fmt);
1727 #ifdef SHARED
1728         if (!runtime) {
1729                 vdprintf(2, fmt, ap);
1730                 dprintf(2, "\n");
1731                 ldso_fail = 1;
1732                 va_end(ap);
1733                 return;
1734         }
1735 #endif
1736         pthread_t self = __pthread_self();
1737         if (self->dlerror_buf != (void *)-1)
1738                 free(self->dlerror_buf);
1739         size_t len = vsnprintf(0, 0, fmt, ap);
1740         va_end(ap);
1741         char *buf = malloc(len+1);
1742         if (buf) {
1743                 va_start(ap, fmt);
1744                 vsnprintf(buf, len+1, fmt, ap);
1745                 va_end(ap);
1746         } else {
1747                 buf = (void *)-1;
1748         }
1749         self->dlerror_buf = buf;
1750         self->dlerror_flag = 1;
1751 }