nsz Git - musl/blob - src/ldso/dynlink.c

   1 #define _GNU_SOURCE
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4 #include <string.h>
   5 #include <unistd.h>
   6 #include <stdint.h>
   7 #include <elf.h>
   8 #include <sys/mman.h>
   9 #include <limits.h>
  10 #include <stdint.h>
  11 #include <fcntl.h>
  12 #include <sys/stat.h>
  13 #include <errno.h>
  14 #include <limits.h>
  15 #include <elf.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
  23 static int errflag;
  24 static char errbuf[128];
  25
  26 #ifdef SHARED
  27
  28 #if ULONG_MAX == 0xffffffff
  29 typedef Elf32_Ehdr Ehdr;
  30 typedef Elf32_Phdr Phdr;
  31 typedef Elf32_Sym Sym;
  32 #define R_TYPE(x) ((x)&255)
  33 #define R_SYM(x) ((x)>>8)
  34 #else
  35 typedef Elf64_Ehdr Ehdr;
  36 typedef Elf64_Phdr Phdr;
  37 typedef Elf64_Sym Sym;
  38 #define R_TYPE(x) ((x)&0xffffffff)
  39 #define R_SYM(x) ((x)>>32)
  40 #endif
  41
  42 #define MAXP2(a,b) (-(-(a)&-(b)))
  43 #define ALIGN(x,y) ((x)+(y)-1 & -(y))
  44
  45 struct debug {
  46         int ver;
  47         void *head;
  48         void (*bp)(void);
  49         int state;
  50         void *base;
  51 };
  52
  53 struct dso {
  54         unsigned char *base;
  55         char *name;
  56         size_t *dynv;
  57         struct dso *next, *prev;
  58
  59         int refcnt;
  60         Sym *syms;
  61         uint32_t *hashtab;
  62         uint32_t *ghashtab;
  63         char *strings;
  64         unsigned char *map;
  65         size_t map_len;
  66         dev_t dev;
  67         ino_t ino;
  68         signed char global;
  69         char relocated;
  70         char constructed;
  71         struct dso **deps;
  72         void *tls_image;
  73         size_t tls_len, tls_size, tls_align, tls_id, tls_offset;
  74         void **new_dtv;
  75         unsigned char *new_tls;
  76         int new_dtv_idx, new_tls_idx;
  77         struct dso *fini_next;
  78         char *shortname;
  79         char buf[];
  80 };
  81
  82 struct symdef {
  83         Sym *sym;
  84         struct dso *dso;
  85 };
  86
  87 #include "reloc.h"
  88
  89 void __init_ssp(size_t *);
  90 void *__install_initial_tls(void *);
  91
  92 static struct dso *head, *tail, *ldso, *fini_head;
  93 static char *env_path, *sys_path, *r_path;
  94 static int ssp_used;
  95 static int runtime;
  96 static int ldd_mode;
  97 static int ldso_fail;
  98 static jmp_buf rtld_fail;
  99 static pthread_rwlock_t lock;
 100 static struct debug debug;
 101 static size_t *auxv;
 102 static size_t tls_cnt, tls_offset, tls_align = 4*sizeof(size_t);
 103 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
 104
 105 struct debug *_dl_debug_addr = &debug;
 106
 107 #define AUX_CNT 38
 108 #define DYN_CNT 34
 109
 110 static void decode_vec(size_t *v, size_t *a, size_t cnt)
 111 {
 112         memset(a, 0, cnt*sizeof(size_t));
 113         for (; v[0]; v+=2) if (v[0]<cnt) {
 114                 a[0] |= 1ULL<<v[0];
 115                 a[v[0]] = v[1];
 116         }
 117 }
 118
 119 static int search_vec(size_t *v, size_t *r, size_t key)
 120 {
 121         for (; v[0]!=key; v+=2)
 122                 if (!v[0]) return 0;
 123         *r = v[1];
 124         return 1;
 125 }
 126
 127 static uint32_t sysv_hash(const char *s0)
 128 {
 129         const unsigned char *s = (void *)s0;
 130         uint_fast32_t h = 0;
 131         while (*s) {
 132                 h = 16*h + *s++;
 133                 h ^= h>>24 & 0xf0;
 134         }
 135         return h & 0xfffffff;
 136 }
 137
 138 static uint32_t gnu_hash(const char *s0)
 139 {
 140         const unsigned char *s = (void *)s0;
 141         uint_fast32_t h = 5381;
 142         for (; *s; s++)
 143                 h = h*33 + *s;
 144         return h;
 145 }
 146
 147 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
 148 {
 149         size_t i;
 150         Sym *syms = dso->syms;
 151         uint32_t *hashtab = dso->hashtab;
 152         char *strings = dso->strings;
 153         for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
 154                 if (!strcmp(s, strings+syms[i].st_name))
 155                         return syms+i;
 156         }
 157         return 0;
 158 }
 159
 160 static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso)
 161 {
 162         Sym *sym;
 163         char *strings;
 164         uint32_t *hashtab = dso->ghashtab;
 165         uint32_t nbuckets = hashtab[0];
 166         uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
 167         uint32_t h2;
 168         uint32_t *hashval;
 169         uint32_t n = buckets[h1 % nbuckets];
 170
 171         if (!n) return 0;
 172
 173         strings = dso->strings;
 174         sym = dso->syms + n;
 175         hashval = buckets + nbuckets + (n - hashtab[1]);
 176
 177         for (h1 |= 1; ; sym++) {
 178                 h2 = *hashval++;
 179                 if ((h1 == (h2|1)) && !strcmp(s, strings + sym->st_name))
 180                         return sym;
 181                 if (h2 & 1) break;
 182         }
 183
 184         return 0;
 185 }
 186
 187 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
 188 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK)
 189
 190 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
 191 {
 192         uint32_t h = 0, gh = 0;
 193         struct symdef def = {0};
 194         if (dso->ghashtab) {
 195                 gh = gnu_hash(s);
 196                 if (gh == 0x1f4039c9 && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
 197         } else {
 198                 h = sysv_hash(s);
 199                 if (h == 0x595a4cc && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
 200         }
 201         for (; dso; dso=dso->next) {
 202                 Sym *sym;
 203                 if (!dso->global) continue;
 204                 if (dso->ghashtab) {
 205                         if (!gh) gh = gnu_hash(s);
 206                         sym = gnu_lookup(s, gh, dso);
 207                 } else {
 208                         if (!h) h = sysv_hash(s);
 209                         sym = sysv_lookup(s, h, dso);
 210                 }
 211                 if (!sym) continue;
 212                 if (!sym->st_shndx)
 213                         if (need_def || (sym->st_info&0xf) == STT_TLS)
 214                                 continue;
 215                 if (!sym->st_value)
 216                         if ((sym->st_info&0xf) != STT_TLS)
 217                                 continue;
 218                 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
 219                 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
 220
 221                 if (def.sym && sym->st_info>>4 == STB_WEAK) continue;
 222                 def.sym = sym;
 223                 def.dso = dso;
 224                 if (sym->st_info>>4 == STB_GLOBAL) break;
 225         }
 226         return def;
 227 }
 228
 229 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
 230 {
 231         unsigned char *base = dso->base;
 232         Sym *syms = dso->syms;
 233         char *strings = dso->strings;
 234         Sym *sym;
 235         const char *name;
 236         void *ctx;
 237         int type;
 238         int sym_index;
 239         struct symdef def;
 240
 241         for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
 242                 type = R_TYPE(rel[1]);
 243                 sym_index = R_SYM(rel[1]);
 244                 if (sym_index) {
 245                         sym = syms + sym_index;
 246                         name = strings + sym->st_name;
 247                         ctx = IS_COPY(type) ? head->next : head;
 248                         def = find_sym(ctx, name, IS_PLT(type));
 249                         if (!def.sym && sym->st_info>>4 != STB_WEAK) {
 250                                 snprintf(errbuf, sizeof errbuf,
 251                                         "Error relocating %s: %s: symbol not found",
 252                                         dso->name, name);
 253                                 if (runtime) longjmp(rtld_fail, 1);
 254                                 dprintf(2, "%s\n", errbuf);
 255                                 ldso_fail = 1;
 256                                 continue;
 257                         }
 258                 } else {
 259                         sym = 0;
 260                         def.sym = 0;
 261                         def.dso = 0;
 262                 }
 263                 do_single_reloc(dso, base, (void *)(base + rel[0]), type,
 264                         stride>2 ? rel[2] : 0, sym, sym?sym->st_size:0, def,
 265                         def.sym?(size_t)(def.dso->base+def.sym->st_value):0);
 266         }
 267 }
 268
 269 /* A huge hack: to make up for the wastefulness of shared libraries
 270  * needing at least a page of dirty memory even if they have no global
 271  * data, we reclaim the gaps at the beginning and end of writable maps
 272  * and "donate" them to the heap by setting up minimal malloc
 273  * structures and then freeing them. */
 274
 275 static void reclaim(unsigned char *base, size_t start, size_t end)
 276 {
 277         size_t *a, *z;
 278         start = start + 6*sizeof(size_t)-1 & -4*sizeof(size_t);
 279         end = (end & -4*sizeof(size_t)) - 2*sizeof(size_t);
 280         if (start>end || end-start < 4*sizeof(size_t)) return;
 281         a = (size_t *)(base + start);
 282         z = (size_t *)(base + end);
 283         a[-2] = 1;
 284         a[-1] = z[0] = end-start + 2*sizeof(size_t) | 1;
 285         z[1] = 1;
 286         free(a);
 287 }
 288
 289 static void reclaim_gaps(unsigned char *base, Phdr *ph, size_t phent, size_t phcnt)
 290 {
 291         for (; phcnt--; ph=(void *)((char *)ph+phent)) {
 292                 if (ph->p_type!=PT_LOAD) continue;
 293                 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
 294                 reclaim(base, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
 295                 reclaim(base, ph->p_vaddr+ph->p_memsz,
 296                         ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
 297         }
 298 }
 299
 300 static void *map_library(int fd, struct dso *dso)
 301 {
 302         Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
 303         size_t phsize;
 304         size_t addr_min=SIZE_MAX, addr_max=0, map_len;
 305         size_t this_min, this_max;
 306         off_t off_start;
 307         Ehdr *eh;
 308         Phdr *ph;
 309         unsigned prot;
 310         unsigned char *map, *base;
 311         size_t dyn;
 312         size_t tls_image=0;
 313         size_t i;
 314
 315         ssize_t l = read(fd, buf, sizeof buf);
 316         if (l<sizeof *eh) return 0;
 317         eh = buf;
 318         phsize = eh->e_phentsize * eh->e_phnum;
 319         if (phsize + sizeof *eh > l) return 0;
 320         if (eh->e_phoff + phsize > l) {
 321                 l = pread(fd, buf+1, phsize, eh->e_phoff);
 322                 if (l != phsize) return 0;
 323                 eh->e_phoff = sizeof *eh;
 324         }
 325         ph = (void *)((char *)buf + eh->e_phoff);
 326         for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
 327                 if (ph->p_type == PT_DYNAMIC)
 328                         dyn = ph->p_vaddr;
 329                 if (ph->p_type == PT_TLS) {
 330                         tls_image = ph->p_vaddr;
 331                         dso->tls_align = ph->p_align;
 332                         dso->tls_len = ph->p_filesz;
 333                         dso->tls_size = ph->p_memsz;
 334                 }
 335                 if (ph->p_type != PT_LOAD) continue;
 336                 if (ph->p_vaddr < addr_min) {
 337                         addr_min = ph->p_vaddr;
 338                         off_start = ph->p_offset;
 339                         prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
 340                                 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
 341                                 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
 342                 }
 343                 if (ph->p_vaddr+ph->p_memsz > addr_max) {
 344                         addr_max = ph->p_vaddr+ph->p_memsz;
 345                 }
 346         }
 347         if (!dyn) return 0;
 348         addr_max += PAGE_SIZE-1;
 349         addr_max &= -PAGE_SIZE;
 350         addr_min &= -PAGE_SIZE;
 351         off_start &= -PAGE_SIZE;
 352         map_len = addr_max - addr_min + off_start;
 353         /* The first time, we map too much, possibly even more than
 354          * the length of the file. This is okay because we will not
 355          * use the invalid part; we just need to reserve the right
 356          * amount of virtual address space to map over later. */
 357         map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start);
 358         if (map==MAP_FAILED) return 0;
 359         base = map - addr_min;
 360         ph = (void *)((char *)buf + eh->e_phoff);
 361         for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
 362                 if (ph->p_type != PT_LOAD) continue;
 363                 /* Reuse the existing mapping for the lowest-address LOAD */
 364                 if ((ph->p_vaddr & -PAGE_SIZE) == addr_min) continue;
 365                 this_min = ph->p_vaddr & -PAGE_SIZE;
 366                 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
 367                 off_start = ph->p_offset & -PAGE_SIZE;
 368                 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
 369                         ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
 370                         ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
 371                 if (mmap(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
 372                         goto error;
 373                 if (ph->p_memsz > ph->p_filesz) {
 374                         size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
 375                         size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
 376                         memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
 377                         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)
 378                                 goto error;
 379                 }
 380         }
 381         for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
 382                 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
 383                         if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC) < 0)
 384                                 goto error;
 385                         break;
 386                 }
 387         if (!runtime) reclaim_gaps(base, (void *)((char *)buf + eh->e_phoff),
 388                 eh->e_phentsize, eh->e_phnum);
 389         dso->map = map;
 390         dso->map_len = map_len;
 391         dso->base = base;
 392         dso->dynv = (void *)(base+dyn);
 393         if (dso->tls_size) dso->tls_image = (void *)(base+tls_image);
 394         return map;
 395 error:
 396         munmap(map, map_len);
 397         return 0;
 398 }
 399
 400 static int path_open(const char *name, const char *search, char *buf, size_t buf_size)
 401 {
 402         const char *s=search, *z;
 403         int l, fd;
 404         for (;;) {
 405                 while (*s==':') s++;
 406                 if (!*s) return -1;
 407                 z = strchr(s, ':');
 408                 l = z ? z-s : strlen(s);
 409                 snprintf(buf, buf_size, "%.*s/%s", l, s, name);
 410                 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
 411                 s += l;
 412         }
 413 }
 414
 415 static void decode_dyn(struct dso *p)
 416 {
 417         size_t dyn[DYN_CNT] = {0};
 418         decode_vec(p->dynv, dyn, DYN_CNT);
 419         p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
 420         p->strings = (void *)(p->base + dyn[DT_STRTAB]);
 421         if (dyn[0]&(1<<DT_HASH))
 422                 p->hashtab = (void *)(p->base + dyn[DT_HASH]);
 423         if (search_vec(p->dynv, dyn, DT_GNU_HASH))
 424                 p->ghashtab = (void *)(p->base + *dyn);
 425 }
 426
 427 static struct dso *load_library(const char *name)
 428 {
 429         char buf[2*NAME_MAX+2];
 430         const char *pathname;
 431         unsigned char *base, *map;
 432         size_t dyno, map_len;
 433         struct dso *p, temp_dso = {0};
 434         int fd;
 435         struct stat st;
 436         size_t alloc_size;
 437         int n_th = 0;
 438
 439         /* Catch and block attempts to reload the implementation itself */
 440         if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
 441                 static const char *rp, reserved[] =
 442                         "c\0pthread\0rt\0m\0dl\0util\0xnet\0";
 443                 char *z = strchr(name, '.');
 444                 if (z) {
 445                         size_t l = z-name;
 446                         for (rp=reserved; *rp && memcmp(name+3, rp, l-3); rp+=strlen(rp)+1);
 447                         if (*rp) {
 448                                 if (!ldso->prev) {
 449                                         tail->next = ldso;
 450                                         ldso->prev = tail;
 451                                         tail = ldso->next ? ldso->next : ldso;
 452                                 }
 453                                 return ldso;
 454                         }
 455                 }
 456         }
 457         if (strchr(name, '/')) {
 458                 pathname = name;
 459                 fd = open(name, O_RDONLY|O_CLOEXEC);
 460         } else {
 461                 /* Search for the name to see if it's already loaded */
 462                 for (p=head->next; p; p=p->next) {
 463                         if (p->shortname && !strcmp(p->shortname, name)) {
 464                                 p->refcnt++;
 465                                 return p;
 466                         }
 467                 }
 468                 if (strlen(name) > NAME_MAX) return 0;
 469                 fd = -1;
 470                 if (r_path) fd = path_open(name, r_path, buf, sizeof buf);
 471                 if (fd < 0 && env_path) fd = path_open(name, env_path, buf, sizeof buf);
 472                 if (fd < 0) {
 473                         if (!sys_path) {
 474                                 FILE *f = fopen(ETC_LDSO_PATH, "rbe");
 475                                 if (f) {
 476                                         if (getline(&sys_path, (size_t[1]){0}, f) > 0)
 477                                                 sys_path[strlen(sys_path)-1]=0;
 478                                         fclose(f);
 479                                 }
 480                         }
 481                         if (sys_path) fd = path_open(name, sys_path, buf, sizeof buf);
 482                         else fd = path_open(name, "/lib:/usr/local/lib:/usr/lib", buf, sizeof buf);
 483                 }
 484                 pathname = buf;
 485         }
 486         if (fd < 0) return 0;
 487         if (fstat(fd, &st) < 0) {
 488                 close(fd);
 489                 return 0;
 490         }
 491         for (p=head->next; p; p=p->next) {
 492                 if (p->dev == st.st_dev && p->ino == st.st_ino) {
 493                         /* If this library was previously loaded with a
 494                          * pathname but a search found the same inode,
 495                          * setup its shortname so it can be found by name. */
 496                         if (!p->shortname && pathname != name)
 497                                 p->shortname = strrchr(p->name, '/')+1;
 498                         close(fd);
 499                         p->refcnt++;
 500                         return p;
 501                 }
 502         }
 503         map = map_library(fd, &temp_dso);
 504         close(fd);
 505         if (!map) return 0;
 506
 507         /* Allocate storage for the new DSO. When there is TLS, this
 508          * storage must include a reservation for all pre-existing
 509          * threads to obtain copies of both the new TLS, and an
 510          * extended DTV capable of storing an additional slot for
 511          * the newly-loaded DSO. */
 512         alloc_size = sizeof *p + strlen(pathname) + 1;
 513         if (runtime && temp_dso.tls_image) {
 514                 size_t per_th = temp_dso.tls_size + temp_dso.tls_align
 515                         + sizeof(void *) * (tls_cnt+3);
 516                 n_th = libc.threads_minus_1 + 1;
 517                 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
 518                 else alloc_size += n_th * per_th;
 519         }
 520         p = calloc(1, alloc_size);
 521         if (!p) {
 522                 munmap(map, map_len);
 523                 return 0;
 524         }
 525         memcpy(p, &temp_dso, sizeof temp_dso);
 526         decode_dyn(p);
 527         p->dev = st.st_dev;
 528         p->ino = st.st_ino;
 529         p->refcnt = 1;
 530         p->name = p->buf;
 531         strcpy(p->name, pathname);
 532         /* Add a shortname only if name arg was not an explicit pathname. */
 533         if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
 534         if (p->tls_image) {
 535                 if (runtime && !__pthread_self_init()) {
 536                         free(p);
 537                         munmap(map, map_len);
 538                         return 0;
 539                 }
 540                 p->tls_id = ++tls_cnt;
 541                 tls_align = MAXP2(tls_align, p->tls_align);
 542 #ifdef TLS_ABOVE_TP
 543                 p->tls_offset = tls_offset + ( (tls_align-1) &
 544                         -(tls_offset + (uintptr_t)p->tls_image) );
 545                 tls_offset += p->tls_size;
 546 #else
 547                 tls_offset += p->tls_size + p->tls_align - 1;
 548                 tls_offset -= (tls_offset + (uintptr_t)p->tls_image)
 549                         & (p->tls_align-1);
 550                 p->tls_offset = tls_offset;
 551 #endif
 552                 p->new_dtv = (void *)(-sizeof(size_t) &
 553                         (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
 554                 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
 555         }
 556
 557         tail->next = p;
 558         p->prev = tail;
 559         tail = p;
 560
 561         if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, base);
 562
 563         return p;
 564 }
 565
 566 static void load_deps(struct dso *p)
 567 {
 568         size_t i, ndeps=0;
 569         struct dso ***deps = &p->deps, **tmp, *dep;
 570         for (; p; p=p->next) {
 571                 for (i=0; p->dynv[i]; i+=2) {
 572                         if (p->dynv[i] != DT_RPATH) continue;
 573                         r_path = (void *)(p->strings + p->dynv[i+1]);
 574                 }
 575                 for (i=0; p->dynv[i]; i+=2) {
 576                         if (p->dynv[i] != DT_NEEDED) continue;
 577                         dep = load_library(p->strings + p->dynv[i+1]);
 578                         if (!dep) {
 579                                 snprintf(errbuf, sizeof errbuf,
 580                                         "Error loading shared library %s: %m (needed by %s)",
 581                                         p->strings + p->dynv[i+1], p->name);
 582                                 if (runtime) longjmp(rtld_fail, 1);
 583                                 dprintf(2, "%s\n", errbuf);
 584                                 ldso_fail = 1;
 585                                 continue;
 586                         }
 587                         if (runtime) {
 588                                 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
 589                                 if (!tmp) longjmp(rtld_fail, 1);
 590                                 tmp[ndeps++] = dep;
 591                                 tmp[ndeps] = 0;
 592                                 *deps = tmp;
 593                         }
 594                 }
 595                 r_path = 0;
 596         }
 597 }
 598
 599 static void load_preload(char *s)
 600 {
 601         int tmp;
 602         char *z;
 603         for (z=s; *z; s=z) {
 604                 for (   ; *s && isspace(*s); s++);
 605                 for (z=s; *z && !isspace(*z); z++);
 606                 tmp = *z;
 607                 *z = 0;
 608                 load_library(s);
 609                 *z = tmp;
 610         }
 611 }
 612
 613 static void make_global(struct dso *p)
 614 {
 615         for (; p; p=p->next) p->global = 1;
 616 }
 617
 618 static void reloc_all(struct dso *p)
 619 {
 620         size_t dyn[DYN_CNT] = {0};
 621         for (; p; p=p->next) {
 622                 if (p->relocated) continue;
 623                 decode_vec(p->dynv, dyn, DYN_CNT);
 624 #ifdef NEED_ARCH_RELOCS
 625                 do_arch_relocs(p, head);
 626 #endif
 627                 do_relocs(p, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
 628                         2+(dyn[DT_PLTREL]==DT_RELA));
 629                 do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2);
 630                 do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
 631                 p->relocated = 1;
 632         }
 633 }
 634
 635 static size_t find_dyn(Phdr *ph, size_t cnt, size_t stride)
 636 {
 637         for (; cnt--; ph = (void *)((char *)ph + stride))
 638                 if (ph->p_type == PT_DYNAMIC)
 639                         return ph->p_vaddr;
 640         return 0;
 641 }
 642
 643 static void find_map_range(Phdr *ph, size_t cnt, size_t stride, struct dso *p)
 644 {
 645         size_t min_addr = -1, max_addr = 0;
 646         for (; cnt--; ph = (void *)((char *)ph + stride)) {
 647                 if (ph->p_type != PT_LOAD) continue;
 648                 if (ph->p_vaddr < min_addr)
 649                         min_addr = ph->p_vaddr;
 650                 if (ph->p_vaddr+ph->p_memsz > max_addr)
 651                         max_addr = ph->p_vaddr+ph->p_memsz;
 652         }
 653         min_addr &= -PAGE_SIZE;
 654         max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
 655         p->map = p->base + min_addr;
 656         p->map_len = max_addr - min_addr;
 657 }
 658
 659 static void do_fini()
 660 {
 661         struct dso *p;
 662         size_t dyn[DYN_CNT] = {0};
 663         for (p=fini_head; p; p=p->fini_next) {
 664                 if (!p->constructed) continue;
 665                 decode_vec(p->dynv, dyn, DYN_CNT);
 666                 ((void (*)(void))(p->base + dyn[DT_FINI]))();
 667         }
 668 }
 669
 670 static void do_init_fini(struct dso *p)
 671 {
 672         size_t dyn[DYN_CNT] = {0};
 673         int need_locking = libc.threads_minus_1;
 674         /* Allow recursive calls that arise when a library calls
 675          * dlopen from one of its constructors, but block any
 676          * other threads until all ctors have finished. */
 677         if (need_locking) pthread_mutex_lock(&init_fini_lock);
 678         for (; p; p=p->prev) {
 679                 if (p->constructed) continue;
 680                 p->constructed = 1;
 681                 decode_vec(p->dynv, dyn, DYN_CNT);
 682                 if (dyn[0] & (1<<DT_FINI)) {
 683                         p->fini_next = fini_head;
 684                         fini_head = p;
 685                 }
 686                 if (dyn[0] & (1<<DT_INIT))
 687                         ((void (*)(void))(p->base + dyn[DT_INIT]))();
 688         }
 689         if (need_locking) pthread_mutex_unlock(&init_fini_lock);
 690 }
 691
 692 void _dl_debug_state(void)
 693 {
 694 }
 695
 696 void *__copy_tls(unsigned char *mem)
 697 {
 698         pthread_t td;
 699         struct dso *p;
 700
 701         if (!tls_cnt) return mem;
 702
 703         void **dtv = (void *)mem;
 704         dtv[0] = (void *)tls_cnt;
 705
 706 #ifdef TLS_ABOVE_TP
 707         mem += sizeof(void *) * (tls_cnt+1);
 708         mem += -((uintptr_t)mem + sizeof(struct pthread)) & (tls_align-1);
 709         td = (pthread_t)mem;
 710         mem += sizeof(struct pthread);
 711
 712         for (p=head; p; p=p->next) {
 713                 if (!p->tls_id) continue;
 714                 dtv[p->tls_id] = mem + p->tls_offset;
 715                 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
 716         }
 717 #else
 718         mem += libc.tls_size - sizeof(struct pthread);
 719         mem -= (uintptr_t)mem & (tls_align-1);
 720         td = (pthread_t)mem;
 721
 722         for (p=head; p; p=p->next) {
 723                 if (!p->tls_id) continue;
 724                 dtv[p->tls_id] = mem - p->tls_offset;
 725                 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
 726         }
 727 #endif
 728         td->dtv = dtv;
 729         return td;
 730 }
 731
 732 void *__tls_get_addr(size_t *v)
 733 {
 734         pthread_t self = __pthread_self();
 735         if (self->dtv && v[0]<=(size_t)self->dtv[0] && self->dtv[v[0]])
 736                 return (char *)self->dtv[v[0]]+v[1];
 737
 738         /* Block signals to make accessing new TLS async-signal-safe */
 739         sigset_t set;
 740         pthread_sigmask(SIG_BLOCK, SIGALL_SET, &set);
 741         if (self->dtv && v[0]<=(size_t)self->dtv[0] && self->dtv[v[0]]) {
 742                 pthread_sigmask(SIG_SETMASK, &set, 0);
 743                 return (char *)self->dtv[v[0]]+v[1];
 744         }
 745
 746         /* This is safe without any locks held because, if the caller
 747          * is able to request the Nth entry of the DTV, the DSO list
 748          * must be valid at least that far out and it was synchronized
 749          * at program startup or by an already-completed call to dlopen. */
 750         struct dso *p;
 751         for (p=head; p->tls_id != v[0]; p=p->next);
 752
 753         /* Get new DTV space from new DSO if needed */
 754         if (!self->dtv || v[0] > (size_t)self->dtv[0]) {
 755                 void **newdtv = p->new_dtv +
 756                         (v[0]+1)*sizeof(void *)*a_fetch_add(&p->new_dtv_idx,1);
 757                 if (self->dtv) memcpy(newdtv, self->dtv,
 758                         ((size_t)self->dtv[0]+1) * sizeof(void *));
 759                 newdtv[0] = (void *)v[0];
 760                 self->dtv = newdtv;
 761         }
 762
 763         /* Get new TLS memory from new DSO */
 764         unsigned char *mem = p->new_tls +
 765                 (p->tls_size + p->tls_align) * a_fetch_add(&p->new_tls_idx,1);
 766         mem += ((uintptr_t)p->tls_image - (uintptr_t)mem) & (p->tls_align-1);
 767         self->dtv[v[0]] = mem;
 768         memcpy(mem, p->tls_image, p->tls_len);
 769         pthread_sigmask(SIG_SETMASK, &set, 0);
 770         return mem + v[1];
 771 }
 772
 773 static void update_tls_size()
 774 {
 775         libc.tls_size = ALIGN(
 776                 (1+tls_cnt) * sizeof(void *) +
 777                 tls_offset +
 778                 sizeof(struct pthread) +
 779                 tls_align * 2,
 780         tls_align);
 781 }
 782
 783 void *__dynlink(int argc, char **argv)
 784 {
 785         size_t aux[AUX_CNT] = {0};
 786         size_t i;
 787         Phdr *phdr;
 788         Ehdr *ehdr;
 789         static struct dso builtin_dsos[3];
 790         struct dso *const app = builtin_dsos+0;
 791         struct dso *const lib = builtin_dsos+1;
 792         struct dso *const vdso = builtin_dsos+2;
 793         char *env_preload=0;
 794         size_t vdso_base;
 795
 796         /* Find aux vector just past environ[] */
 797         for (i=argc+1; argv[i]; i++)
 798                 if (!memcmp(argv[i], "LD_LIBRARY_PATH=", 16))
 799                         env_path = argv[i]+16;
 800                 else if (!memcmp(argv[i], "LD_PRELOAD=", 11))
 801                         env_preload = argv[i]+11;
 802         auxv = (void *)(argv+i+1);
 803
 804         decode_vec(auxv, aux, AUX_CNT);
 805
 806         /* Only trust user/env if kernel says we're not suid/sgid */
 807         if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
 808           || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]) {
 809                 env_path = 0;
 810                 env_preload = 0;
 811         }
 812
 813         /* If the dynamic linker was invoked as a program itself, AT_BASE
 814          * will not be set. In that case, we assume the base address is
 815          * the start of the page containing the PHDRs; I don't know any
 816          * better approach... */
 817         if (!aux[AT_BASE]) {
 818                 aux[AT_BASE] = aux[AT_PHDR] & -PAGE_SIZE;
 819                 aux[AT_PHDR] = aux[AT_PHENT] = aux[AT_PHNUM] = 0;
 820         }
 821
 822         /* The dynamic linker load address is passed by the kernel
 823          * in the AUX vector, so this is easy. */
 824         lib->base = (void *)aux[AT_BASE];
 825         lib->name = lib->shortname = "libc.so";
 826         lib->global = 1;
 827         ehdr = (void *)lib->base;
 828         find_map_range((void *)(aux[AT_BASE]+ehdr->e_phoff),
 829                 ehdr->e_phnum, ehdr->e_phentsize, lib);
 830         lib->dynv = (void *)(lib->base + find_dyn(
 831                 (void *)(aux[AT_BASE]+ehdr->e_phoff),
 832                 ehdr->e_phnum, ehdr->e_phentsize));
 833         decode_dyn(lib);
 834
 835         if (aux[AT_PHDR]) {
 836                 size_t interp_off = 0;
 837                 size_t tls_image = 0;
 838                 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
 839                 phdr = (void *)aux[AT_PHDR];
 840                 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
 841                         if (phdr->p_type == PT_PHDR)
 842                                 app->base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
 843                         else if (phdr->p_type == PT_INTERP)
 844                                 interp_off = (size_t)phdr->p_vaddr;
 845                         else if (phdr->p_type == PT_TLS) {
 846                                 tls_image = phdr->p_vaddr;
 847                                 app->tls_len = phdr->p_filesz;
 848                                 app->tls_size = phdr->p_memsz;
 849                                 app->tls_align = phdr->p_align;
 850                         }
 851                 }
 852                 if (app->tls_size) app->tls_image = (char *)app->base + tls_image;
 853                 if (interp_off) lib->name = (char *)app->base + interp_off;
 854                 app->name = argv[0];
 855                 app->dynv = (void *)(app->base + find_dyn(
 856                         (void *)aux[AT_PHDR], aux[AT_PHNUM], aux[AT_PHENT]));
 857                 find_map_range((void *)aux[AT_PHDR],
 858                         aux[AT_PHNUM], aux[AT_PHENT], app);
 859         } else {
 860                 int fd;
 861                 char *ldname = argv[0];
 862                 size_t dyno, l = strlen(ldname);
 863                 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
 864                 *argv++ = (void *)-1;
 865                 if (argv[0] && !strcmp(argv[0], "--")) *argv++ = (void *)-1;
 866                 if (!argv[0]) {
 867                         dprintf(2, "musl libc/dynamic program loader\n");
 868                         dprintf(2, "usage: %s pathname%s\n", ldname,
 869                                 ldd_mode ? "" : " [args]");
 870                         _exit(1);
 871                 }
 872                 fd = open(argv[0], O_RDONLY);
 873                 if (fd < 0) {
 874                         dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
 875                         _exit(1);
 876                 }
 877                 runtime = 1;
 878                 ehdr = (void *)map_library(fd, app);
 879                 if (!ehdr) {
 880                         dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
 881                         _exit(1);
 882                 }
 883                 runtime = 0;
 884                 close(fd);
 885                 lib->name = ldname;
 886                 app->name = argv[0];
 887                 aux[AT_ENTRY] = ehdr->e_entry;
 888         }
 889         if (app->tls_size) {
 890                 app->tls_id = tls_cnt = 1;
 891 #ifdef TLS_ABOVE_TP
 892                 app->tls_offset = 0;
 893                 tls_offset = app->tls_size
 894                         + ( -((uintptr_t)app->tls_image + app->tls_size)
 895                         & (app->tls_align-1) );
 896 #else
 897                 tls_offset = app->tls_offset = app->tls_size
 898                         + ( -((uintptr_t)app->tls_image + app->tls_size)
 899                         & (app->tls_align-1) );
 900 #endif
 901                 tls_align = MAXP2(tls_align, app->tls_align);
 902         }
 903         app->global = 1;
 904         app->constructed = 1;
 905         decode_dyn(app);
 906
 907         /* Attach to vdso, if provided by the kernel */
 908         if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
 909                 ehdr = (void *)vdso_base;
 910                 phdr = (void *)(vdso_base + ehdr->e_phoff);
 911                 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
 912                         if (phdr->p_type == PT_DYNAMIC)
 913                                 vdso->dynv = (void *)(vdso_base + phdr->p_offset);
 914                         if (phdr->p_type == PT_LOAD)
 915                                 vdso->base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
 916                 }
 917                 vdso->name = vdso->shortname = "linux-gate.so.1";
 918                 vdso->global = 1;
 919                 decode_dyn(vdso);
 920                 vdso->prev = lib;
 921                 lib->next = vdso;
 922         }
 923
 924         /* Initial dso chain consists only of the app. We temporarily
 925          * append the dynamic linker/libc so we can relocate it, then
 926          * restore the initial chain in preparation for loading third
 927          * party libraries (preload/needed). */
 928         head = tail = app;
 929         ldso = lib;
 930         app->next = lib;
 931         reloc_all(lib);
 932         app->next = 0;
 933
 934         /* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */
 935
 936         /* Donate unused parts of app and library mapping to malloc */
 937         reclaim_gaps(app->base, (void *)aux[AT_PHDR], aux[AT_PHENT], aux[AT_PHNUM]);
 938         ehdr = (void *)lib->base;
 939         reclaim_gaps(lib->base, (void *)(lib->base+ehdr->e_phoff),
 940                 ehdr->e_phentsize, ehdr->e_phnum);
 941
 942         /* Load preload/needed libraries, add their symbols to the global
 943          * namespace, and perform all remaining relocations. The main
 944          * program must be relocated LAST since it may contain copy
 945          * relocations which depend on libraries' relocations. */
 946         if (env_preload) load_preload(env_preload);
 947         load_deps(app);
 948         make_global(app);
 949
 950         reloc_all(app->next);
 951         reloc_all(app);
 952
 953         update_tls_size();
 954         if (tls_cnt) {
 955                 struct dso *p;
 956                 void *mem = mmap(0, libc.tls_size, PROT_READ|PROT_WRITE,
 957                         MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
 958                 if (mem==MAP_FAILED ||
 959                     !__install_initial_tls(__copy_tls(mem))) {
 960                         dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
 961                                 argv[0], libc.tls_size);
 962                         _exit(127);
 963                 }
 964         }
 965
 966         if (ldso_fail) _exit(127);
 967         if (ldd_mode) _exit(0);
 968
 969         /* Switch to runtime mode: any further failures in the dynamic
 970          * linker are a reportable failure rather than a fatal startup
 971          * error. If the dynamic loader (dlopen) will not be used, free
 972          * all memory used by the dynamic linker. */
 973         runtime = 1;
 974
 975 #ifndef DYNAMIC_IS_RO
 976         for (i=0; app->dynv[i]; i+=2)
 977                 if (app->dynv[i]==DT_DEBUG)
 978                         app->dynv[i+1] = (size_t)&debug;
 979 #endif
 980         debug.ver = 1;
 981         debug.bp = _dl_debug_state;
 982         debug.head = head;
 983         debug.base = lib->base;
 984         debug.state = 0;
 985         _dl_debug_state();
 986
 987         if (ssp_used) __init_ssp((void *)aux[AT_RANDOM]);
 988
 989         atexit(do_fini);
 990         do_init_fini(tail);
 991
 992         errno = 0;
 993         return (void *)aux[AT_ENTRY];
 994 }
 995
 996 void *dlopen(const char *file, int mode)
 997 {
 998         struct dso *volatile p, *orig_tail, *next;
 999         size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1000         size_t i;
1001         int cs;
1002
1003         if (!file) return head;
1004
1005         pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1006         pthread_rwlock_wrlock(&lock);
1007         __inhibit_ptc();
1008
1009         p = 0;
1010         orig_tls_cnt = tls_cnt;
1011         orig_tls_offset = tls_offset;
1012         orig_tls_align = tls_align;
1013         orig_tail = tail;
1014
1015         if (setjmp(rtld_fail)) {
1016                 /* Clean up anything new that was (partially) loaded */
1017                 if (p && p->deps) for (i=0; p->deps[i]; i++)
1018                         if (p->deps[i]->global < 0)
1019                                 p->deps[i]->global = 0;
1020                 for (p=orig_tail->next; p; p=next) {
1021                         next = p->next;
1022                         munmap(p->map, p->map_len);
1023                         free(p->deps);
1024                         free(p);
1025                 }
1026                 tls_cnt = orig_tls_cnt;
1027                 tls_offset = orig_tls_offset;
1028                 tls_align = orig_tls_align;
1029                 tail = orig_tail;
1030                 tail->next = 0;
1031                 p = 0;
1032                 errflag = 1;
1033                 goto end;
1034         } else p = load_library(file);
1035
1036         if (!p) {
1037                 snprintf(errbuf, sizeof errbuf,
1038                         "Error loading shared library %s: %m", file);
1039                 errflag = 1;
1040                 goto end;
1041         }
1042
1043         /* First load handling */
1044         if (!p->deps) {
1045                 load_deps(p);
1046                 if (p->deps) for (i=0; p->deps[i]; i++)
1047                         if (!p->deps[i]->global)
1048                                 p->deps[i]->global = -1;
1049                 if (!p->global) p->global = -1;
1050                 reloc_all(p);
1051                 if (p->deps) for (i=0; p->deps[i]; i++)
1052                         if (p->deps[i]->global < 0)
1053                                 p->deps[i]->global = 0;
1054                 if (p->global < 0) p->global = 0;
1055         }
1056
1057         if (mode & RTLD_GLOBAL) {
1058                 if (p->deps) for (i=0; p->deps[i]; i++)
1059                         p->deps[i]->global = 1;
1060                 p->global = 1;
1061         }
1062
1063         update_tls_size();
1064
1065         if (ssp_used) __init_ssp(auxv);
1066
1067         _dl_debug_state();
1068         orig_tail = tail;
1069 end:
1070         __release_ptc();
1071         pthread_rwlock_unlock(&lock);
1072         if (p) do_init_fini(orig_tail);
1073         pthread_setcancelstate(cs, 0);
1074         return p;
1075 }
1076
1077 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1078 {
1079         size_t i;
1080         uint32_t h = 0, gh = 0;
1081         Sym *sym;
1082         if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1083                 if (p == RTLD_NEXT) {
1084                         for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
1085                         if (!p) p=head;
1086                 }
1087                 struct symdef def = find_sym(p->next, s, 0);
1088                 if (!def.sym) goto failed;
1089                 return def.dso->base + def.sym->st_value;
1090         }
1091         if (p->ghashtab) {
1092                 gh = gnu_hash(s);
1093                 sym = gnu_lookup(s, gh, p);
1094         } else {
1095                 h = sysv_hash(s);
1096                 sym = sysv_lookup(s, h, p);
1097         }
1098         if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1099                 return p->base + sym->st_value;
1100         if (p->deps) for (i=0; p->deps[i]; i++) {
1101                 if (p->deps[i]->ghashtab) {
1102                         if (!gh) gh = gnu_hash(s);
1103                         sym = gnu_lookup(s, gh, p->deps[i]);
1104                 } else {
1105                         if (!h) h = sysv_hash(s);
1106                         sym = sysv_lookup(s, h, p->deps[i]);
1107                 }
1108                 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1109                         return p->deps[i]->base + sym->st_value;
1110         }
1111 failed:
1112         errflag = 1;
1113         snprintf(errbuf, sizeof errbuf, "Symbol not found: %s", s);
1114         return 0;
1115 }
1116
1117 int __dladdr(void *addr, Dl_info *info)
1118 {
1119         struct dso *p;
1120         Sym *sym;
1121         uint32_t nsym;
1122         char *strings;
1123         size_t i;
1124         void *best = 0;
1125         char *bestname;
1126
1127         pthread_rwlock_rdlock(&lock);
1128         for (p=head; p && (unsigned char *)addr-p->map>p->map_len; p=p->next);
1129         pthread_rwlock_unlock(&lock);
1130
1131         if (!p) return 0;
1132
1133         sym = p->syms;
1134         strings = p->strings;
1135         if (p->hashtab) {
1136                 nsym = p->hashtab[1];
1137         } else {
1138                 uint32_t *buckets;
1139                 uint32_t *hashval;
1140                 buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
1141                 sym += p->ghashtab[1];
1142                 for (i = 0; i < p->ghashtab[0]; i++) {
1143                         if (buckets[i] > nsym)
1144                                 nsym = buckets[i];
1145                 }
1146                 if (nsym) {
1147                         nsym -= p->ghashtab[1];
1148                         hashval = buckets + p->ghashtab[0] + nsym;
1149                         do nsym++;
1150                         while (!(*hashval++ & 1));
1151                 }
1152         }
1153
1154         for (; nsym; nsym--, sym++) {
1155                 if (sym->st_shndx && sym->st_value
1156                  && (1<<(sym->st_info&0xf) & OK_TYPES)
1157                  && (1<<(sym->st_info>>4) & OK_BINDS)) {
1158                         void *symaddr = p->base + sym->st_value;
1159                         if (symaddr > addr || symaddr < best)
1160                                 continue;
1161                         best = symaddr;
1162                         bestname = strings + sym->st_name;
1163                         if (addr == symaddr)
1164                                 break;
1165                 }
1166         }
1167
1168         if (!best) return 0;
1169
1170         info->dli_fname = p->name;
1171         info->dli_fbase = p->base;
1172         info->dli_sname = bestname;
1173         info->dli_saddr = best;
1174
1175         return 1;
1176 }
1177
1178 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1179 {
1180         void *res;
1181         pthread_rwlock_rdlock(&lock);
1182         res = do_dlsym(p, s, ra);
1183         pthread_rwlock_unlock(&lock);
1184         return res;
1185 }
1186 #else
1187 void *dlopen(const char *file, int mode)
1188 {
1189         return 0;
1190 }
1191 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1192 {
1193         return 0;
1194 }
1195 int __dladdr (void *addr, Dl_info *info)
1196 {
1197         return 0;
1198 }
1199 #endif
1200
1201 char *dlerror()
1202 {
1203         if (!errflag) return 0;
1204         errflag = 0;
1205         return errbuf;
1206 }
1207
1208 int dlclose(void *p)
1209 {
1210         return 0;
1211 }