21 #include "pthread_impl.h"
25 static char errbuf[128];
29 #if ULONG_MAX == 0xffffffff
30 typedef Elf32_Ehdr Ehdr;
31 typedef Elf32_Phdr Phdr;
32 typedef Elf32_Sym Sym;
33 #define R_TYPE(x) ((x)&255)
34 #define R_SYM(x) ((x)>>8)
36 typedef Elf64_Ehdr Ehdr;
37 typedef Elf64_Phdr Phdr;
38 typedef Elf64_Sym Sym;
39 #define R_TYPE(x) ((x)&0xffffffff)
40 #define R_SYM(x) ((x)>>32)
43 #define MAXP2(a,b) (-(-(a)&-(b)))
44 #define ALIGN(x,y) ((x)+(y)-1 & -(y))
58 struct dso *next, *prev;
76 size_t tls_len, tls_size, tls_align, tls_id, tls_offset;
78 unsigned char *new_tls;
79 int new_dtv_idx, new_tls_idx;
80 struct dso *fini_next;
92 void __init_ssp(size_t *);
93 void *__install_initial_tls(void *);
94 void __init_libc(char **, char *);
96 static struct dso *head, *tail, *ldso, *fini_head;
97 static char *env_path, *sys_path, *r_path;
98 static unsigned long long gencnt;
102 static int ldso_fail;
104 static jmp_buf *rtld_fail;
105 static pthread_rwlock_t lock;
106 static struct debug debug;
107 static size_t tls_cnt, tls_offset, tls_align = 4*sizeof(size_t);
108 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
110 struct debug *_dl_debug_addr = &debug;
115 static void decode_vec(size_t *v, size_t *a, size_t cnt)
117 memset(a, 0, cnt*sizeof(size_t));
118 for (; v[0]; v+=2) if (v[0]<cnt) {
124 static int search_vec(size_t *v, size_t *r, size_t key)
126 for (; v[0]!=key; v+=2)
132 static uint32_t sysv_hash(const char *s0)
134 const unsigned char *s = (void *)s0;
140 return h & 0xfffffff;
143 static uint32_t gnu_hash(const char *s0)
145 const unsigned char *s = (void *)s0;
146 uint_fast32_t h = 5381;
152 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
155 Sym *syms = dso->syms;
156 uint32_t *hashtab = dso->hashtab;
157 char *strings = dso->strings;
158 for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
159 if (!strcmp(s, strings+syms[i].st_name))
165 static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso)
169 uint32_t *hashtab = dso->ghashtab;
170 uint32_t nbuckets = hashtab[0];
171 uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
174 uint32_t n = buckets[h1 % nbuckets];
178 strings = dso->strings;
180 hashval = buckets + nbuckets + (n - hashtab[1]);
182 for (h1 |= 1; ; sym++) {
184 if ((h1 == (h2|1)) && !strcmp(s, strings + sym->st_name))
192 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
193 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
195 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
197 uint32_t h = 0, gh = 0;
198 struct symdef def = {0};
201 if (gh == 0x1f4039c9 && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
204 if (h == 0x595a4cc && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
206 for (; dso; dso=dso->next) {
208 if (!dso->global) continue;
210 if (!gh) gh = gnu_hash(s);
211 sym = gnu_lookup(s, gh, dso);
213 if (!h) h = sysv_hash(s);
214 sym = sysv_lookup(s, h, dso);
218 if (need_def || (sym->st_info&0xf) == STT_TLS)
221 if ((sym->st_info&0xf) != STT_TLS)
223 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
224 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
226 if (def.sym && sym->st_info>>4 == STB_WEAK) continue;
229 if (sym->st_info>>4 == STB_GLOBAL) break;
234 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
236 unsigned char *base = dso->base;
237 Sym *syms = dso->syms;
238 char *strings = dso->strings;
246 for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
247 type = R_TYPE(rel[1]);
248 sym_index = R_SYM(rel[1]);
250 sym = syms + sym_index;
251 name = strings + sym->st_name;
252 ctx = IS_COPY(type) ? head->next : head;
253 def = find_sym(ctx, name, IS_PLT(type));
254 if (!def.sym && sym->st_info>>4 != STB_WEAK) {
255 snprintf(errbuf, sizeof errbuf,
256 "Error relocating %s: %s: symbol not found",
258 if (runtime) longjmp(*rtld_fail, 1);
259 dprintf(2, "%s\n", errbuf);
268 do_single_reloc(dso, base, (void *)(base + rel[0]), type,
269 stride>2 ? rel[2] : 0, sym, sym?sym->st_size:0, def,
270 def.sym?(size_t)(def.dso->base+def.sym->st_value):0);
274 /* A huge hack: to make up for the wastefulness of shared libraries
275 * needing at least a page of dirty memory even if they have no global
276 * data, we reclaim the gaps at the beginning and end of writable maps
277 * and "donate" them to the heap by setting up minimal malloc
278 * structures and then freeing them. */
280 static void reclaim(unsigned char *base, size_t start, size_t end)
283 start = start + 6*sizeof(size_t)-1 & -4*sizeof(size_t);
284 end = (end & -4*sizeof(size_t)) - 2*sizeof(size_t);
285 if (start>end || end-start < 4*sizeof(size_t)) return;
286 a = (size_t *)(base + start);
287 z = (size_t *)(base + end);
289 a[-1] = z[0] = end-start + 2*sizeof(size_t) | 1;
294 static void reclaim_gaps(unsigned char *base, Phdr *ph, size_t phent, size_t phcnt)
296 for (; phcnt--; ph=(void *)((char *)ph+phent)) {
297 if (ph->p_type!=PT_LOAD) continue;
298 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
299 reclaim(base, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
300 reclaim(base, ph->p_vaddr+ph->p_memsz,
301 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
305 static void *map_library(int fd, struct dso *dso)
307 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
308 void *allocated_buf=0;
310 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
311 size_t this_min, this_max;
316 unsigned char *map=MAP_FAILED, *base;
321 ssize_t l = read(fd, buf, sizeof buf);
324 if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
326 phsize = eh->e_phentsize * eh->e_phnum;
327 if (phsize > sizeof buf - sizeof *eh) {
328 allocated_buf = malloc(phsize);
329 if (!allocated_buf) return 0;
330 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
331 if (l < 0) goto error;
332 if (l != phsize) goto noexec;
333 ph = ph0 = allocated_buf;
334 } else if (eh->e_phoff + phsize > l) {
335 l = pread(fd, buf+1, phsize, eh->e_phoff);
336 if (l < 0) goto error;
337 if (l != phsize) goto noexec;
338 ph = ph0 = (void *)(buf + 1);
340 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
342 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
343 if (ph->p_type == PT_DYNAMIC)
345 if (ph->p_type == PT_TLS) {
346 tls_image = ph->p_vaddr;
347 dso->tls_align = ph->p_align;
348 dso->tls_len = ph->p_filesz;
349 dso->tls_size = ph->p_memsz;
351 if (ph->p_type != PT_LOAD) continue;
352 if (ph->p_vaddr < addr_min) {
353 addr_min = ph->p_vaddr;
354 off_start = ph->p_offset;
355 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
356 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
357 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
359 if (ph->p_vaddr+ph->p_memsz > addr_max) {
360 addr_max = ph->p_vaddr+ph->p_memsz;
363 if (!dyn) goto noexec;
364 addr_max += PAGE_SIZE-1;
365 addr_max &= -PAGE_SIZE;
366 addr_min &= -PAGE_SIZE;
367 off_start &= -PAGE_SIZE;
368 map_len = addr_max - addr_min + off_start;
369 /* The first time, we map too much, possibly even more than
370 * the length of the file. This is okay because we will not
371 * use the invalid part; we just need to reserve the right
372 * amount of virtual address space to map over later. */
373 map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start);
374 if (map==MAP_FAILED) goto error;
375 /* If the loaded file is not relocatable and the requested address is
376 * not available, then the load operation must fail. */
377 if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
381 base = map - addr_min;
384 for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
385 if (ph->p_type != PT_LOAD) continue;
386 /* Check if the programs headers are in this load segment, and
387 * if so, record the address for use by dl_iterate_phdr. */
388 if (!dso->phdr && eh->e_phoff >= ph->p_offset
389 && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
390 dso->phdr = (void *)(base + ph->p_vaddr
391 + (eh->e_phoff-ph->p_offset));
392 dso->phnum = eh->e_phnum;
394 /* Reuse the existing mapping for the lowest-address LOAD */
395 if ((ph->p_vaddr & -PAGE_SIZE) == addr_min) continue;
396 this_min = ph->p_vaddr & -PAGE_SIZE;
397 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
398 off_start = ph->p_offset & -PAGE_SIZE;
399 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
400 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
401 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
402 if (mmap(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
404 if (ph->p_memsz > ph->p_filesz) {
405 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
406 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
407 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
408 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)
412 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
413 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
414 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC) < 0)
418 if (!runtime) reclaim_gaps(base, ph0, eh->e_phentsize, eh->e_phnum);
420 dso->map_len = map_len;
422 dso->dynv = (void *)(base+dyn);
423 if (dso->tls_size) dso->tls_image = (void *)(base+tls_image);
429 if (map!=MAP_FAILED) munmap(map, map_len);
434 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
439 s += strspn(s, ":\n");
440 l = strcspn(s, ":\n");
441 if (l-1 >= INT_MAX) return -1;
442 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) >= buf_size)
444 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
449 static void decode_dyn(struct dso *p)
451 size_t dyn[DYN_CNT] = {0};
452 decode_vec(p->dynv, dyn, DYN_CNT);
453 p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
454 p->strings = (void *)(p->base + dyn[DT_STRTAB]);
455 if (dyn[0]&(1<<DT_HASH))
456 p->hashtab = (void *)(p->base + dyn[DT_HASH]);
457 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
458 p->ghashtab = (void *)(p->base + *dyn);
461 static struct dso *load_library(const char *name)
463 char buf[2*NAME_MAX+2];
464 const char *pathname;
466 struct dso *p, temp_dso = {0};
473 /* Catch and block attempts to reload the implementation itself */
474 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
475 static const char *rp, reserved[] =
476 "c\0pthread\0rt\0m\0dl\0util\0xnet\0";
477 char *z = strchr(name, '.');
480 for (rp=reserved; *rp && strncmp(name+3, rp, l-3); rp+=strlen(rp)+1);
483 /* Track which names have been resolved
484 * and only report each one once. */
485 static unsigned reported;
486 unsigned mask = 1U<<(rp-reserved);
487 if (!(reported & mask)) {
489 dprintf(1, "\t%s => %s (%p)\n",
498 if (!strcmp(name, ldso->name)) is_self = 1;
503 tail = ldso->next ? ldso->next : ldso;
507 if (strchr(name, '/')) {
509 fd = open(name, O_RDONLY|O_CLOEXEC);
511 /* Search for the name to see if it's already loaded */
512 for (p=head->next; p; p=p->next) {
513 if (p->shortname && !strcmp(p->shortname, name)) {
518 if (strlen(name) > NAME_MAX) return 0;
520 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
521 if (fd < 0 && r_path) fd = path_open(name, r_path, buf, sizeof buf);
526 if (ldso->name[0]=='/') {
528 for (s=t=z=ldso->name; *s; s++)
529 if (*s=='/') z=t, t=s;
530 prefix_len = z-ldso->name;
531 if (prefix_len < PATH_MAX)
538 char etc_ldso_path[prefix_len + 1
539 + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
540 snprintf(etc_ldso_path, sizeof etc_ldso_path,
541 "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
542 (int)prefix_len, prefix);
543 FILE *f = fopen(etc_ldso_path, "rbe");
545 if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
552 if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
553 fd = path_open(name, sys_path, buf, sizeof buf);
557 if (fd < 0) return 0;
558 if (fstat(fd, &st) < 0) {
562 for (p=head->next; p; p=p->next) {
563 if (p->dev == st.st_dev && p->ino == st.st_ino) {
564 /* If this library was previously loaded with a
565 * pathname but a search found the same inode,
566 * setup its shortname so it can be found by name. */
567 if (!p->shortname && pathname != name)
568 p->shortname = strrchr(p->name, '/')+1;
574 map = noload ? 0 : map_library(fd, &temp_dso);
578 /* Allocate storage for the new DSO. When there is TLS, this
579 * storage must include a reservation for all pre-existing
580 * threads to obtain copies of both the new TLS, and an
581 * extended DTV capable of storing an additional slot for
582 * the newly-loaded DSO. */
583 alloc_size = sizeof *p + strlen(pathname) + 1;
584 if (runtime && temp_dso.tls_image) {
585 size_t per_th = temp_dso.tls_size + temp_dso.tls_align
586 + sizeof(void *) * (tls_cnt+3);
587 n_th = libc.threads_minus_1 + 1;
588 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
589 else alloc_size += n_th * per_th;
591 p = calloc(1, alloc_size);
593 munmap(map, temp_dso.map_len);
596 memcpy(p, &temp_dso, sizeof temp_dso);
602 strcpy(p->name, pathname);
603 /* Add a shortname only if name arg was not an explicit pathname. */
604 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
606 if (runtime && !__pthread_self_init()) {
607 munmap(map, p->map_len);
611 p->tls_id = ++tls_cnt;
612 tls_align = MAXP2(tls_align, p->tls_align);
614 p->tls_offset = tls_offset + ( (tls_align-1) &
615 -(tls_offset + (uintptr_t)p->tls_image) );
616 tls_offset += p->tls_size;
618 tls_offset += p->tls_size + p->tls_align - 1;
619 tls_offset -= (tls_offset + (uintptr_t)p->tls_image)
621 p->tls_offset = tls_offset;
623 p->new_dtv = (void *)(-sizeof(size_t) &
624 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
625 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
632 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
637 static void load_deps(struct dso *p)
640 struct dso ***deps = &p->deps, **tmp, *dep;
641 for (; p; p=p->next) {
642 for (i=0; p->dynv[i]; i+=2) {
643 if (p->dynv[i] != DT_RPATH) continue;
644 r_path = (void *)(p->strings + p->dynv[i+1]);
646 for (i=0; p->dynv[i]; i+=2) {
647 if (p->dynv[i] != DT_NEEDED) continue;
648 dep = load_library(p->strings + p->dynv[i+1]);
650 snprintf(errbuf, sizeof errbuf,
651 "Error loading shared library %s: %m (needed by %s)",
652 p->strings + p->dynv[i+1], p->name);
653 if (runtime) longjmp(*rtld_fail, 1);
654 dprintf(2, "%s\n", errbuf);
659 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
660 if (!tmp) longjmp(*rtld_fail, 1);
670 static void load_preload(char *s)
675 for ( ; *s && isspace(*s); s++);
676 for (z=s; *z && !isspace(*z); z++);
684 static void make_global(struct dso *p)
686 for (; p; p=p->next) p->global = 1;
689 static void reloc_all(struct dso *p)
691 size_t dyn[DYN_CNT] = {0};
692 for (; p; p=p->next) {
693 if (p->relocated) continue;
694 decode_vec(p->dynv, dyn, DYN_CNT);
695 #ifdef NEED_ARCH_RELOCS
696 do_arch_relocs(p, head);
698 do_relocs(p, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
699 2+(dyn[DT_PLTREL]==DT_RELA));
700 do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2);
701 do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
706 static size_t find_dyn(Phdr *ph, size_t cnt, size_t stride)
708 for (; cnt--; ph = (void *)((char *)ph + stride))
709 if (ph->p_type == PT_DYNAMIC)
714 static void find_map_range(Phdr *ph, size_t cnt, size_t stride, struct dso *p)
716 size_t min_addr = -1, max_addr = 0;
717 for (; cnt--; ph = (void *)((char *)ph + stride)) {
718 if (ph->p_type != PT_LOAD) continue;
719 if (ph->p_vaddr < min_addr)
720 min_addr = ph->p_vaddr;
721 if (ph->p_vaddr+ph->p_memsz > max_addr)
722 max_addr = ph->p_vaddr+ph->p_memsz;
724 min_addr &= -PAGE_SIZE;
725 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
726 p->map = p->base + min_addr;
727 p->map_len = max_addr - min_addr;
730 static void do_fini()
733 size_t dyn[DYN_CNT] = {0};
734 for (p=fini_head; p; p=p->fini_next) {
735 if (!p->constructed) continue;
736 decode_vec(p->dynv, dyn, DYN_CNT);
737 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
738 size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
739 size_t *fn = (size_t *)(p->base + dyn[DT_FINI_ARRAY])+n;
740 while (n--) ((void (*)(void))*--fn)();
742 #ifndef NO_LEGACY_INITFINI
743 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
744 ((void (*)(void))(p->base + dyn[DT_FINI]))();
749 static void do_init_fini(struct dso *p)
751 size_t dyn[DYN_CNT] = {0};
752 int need_locking = libc.threads_minus_1;
753 /* Allow recursive calls that arise when a library calls
754 * dlopen from one of its constructors, but block any
755 * other threads until all ctors have finished. */
756 if (need_locking) pthread_mutex_lock(&init_fini_lock);
757 for (; p; p=p->prev) {
758 if (p->constructed) continue;
760 decode_vec(p->dynv, dyn, DYN_CNT);
761 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
762 p->fini_next = fini_head;
765 #ifndef NO_LEGACY_INITFINI
766 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
767 ((void (*)(void))(p->base + dyn[DT_INIT]))();
769 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
770 size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
771 size_t *fn = (void *)(p->base + dyn[DT_INIT_ARRAY]);
772 while (n--) ((void (*)(void))*fn++)();
774 if (!need_locking && libc.threads_minus_1) {
776 pthread_mutex_lock(&init_fini_lock);
779 if (need_locking) pthread_mutex_unlock(&init_fini_lock);
782 void _dl_debug_state(void)
788 pthread_t self = __pthread_self();
790 for (p=head; p; p=p->next) {
791 if (!p->tls_id || !self->dtv[p->tls_id]) continue;
792 memcpy(self->dtv[p->tls_id], p->tls_image, p->tls_len);
793 memset((char *)self->dtv[p->tls_id]+p->tls_len, 0,
794 p->tls_size - p->tls_len);
795 if (p->tls_id == (size_t)self->dtv[0]) break;
799 void *__copy_tls(unsigned char *mem)
804 if (!tls_cnt) return mem;
806 void **dtv = (void *)mem;
807 dtv[0] = (void *)tls_cnt;
810 mem += sizeof(void *) * (tls_cnt+1);
811 mem += -((uintptr_t)mem + sizeof(struct pthread)) & (tls_align-1);
813 mem += sizeof(struct pthread);
815 for (p=head; p; p=p->next) {
816 if (!p->tls_id) continue;
817 dtv[p->tls_id] = mem + p->tls_offset;
818 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
821 mem += libc.tls_size - sizeof(struct pthread);
822 mem -= (uintptr_t)mem & (tls_align-1);
825 for (p=head; p; p=p->next) {
826 if (!p->tls_id) continue;
827 dtv[p->tls_id] = mem - p->tls_offset;
828 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
835 void *__tls_get_addr(size_t *v)
837 pthread_t self = __pthread_self();
838 if (v[0]<=(size_t)self->dtv[0] && self->dtv[v[0]])
839 return (char *)self->dtv[v[0]]+v[1];
841 /* Block signals to make accessing new TLS async-signal-safe */
843 pthread_sigmask(SIG_BLOCK, SIGALL_SET, &set);
844 if (v[0]<=(size_t)self->dtv[0] && self->dtv[v[0]]) {
845 pthread_sigmask(SIG_SETMASK, &set, 0);
846 return (char *)self->dtv[v[0]]+v[1];
849 /* This is safe without any locks held because, if the caller
850 * is able to request the Nth entry of the DTV, the DSO list
851 * must be valid at least that far out and it was synchronized
852 * at program startup or by an already-completed call to dlopen. */
854 for (p=head; p->tls_id != v[0]; p=p->next);
856 /* Get new DTV space from new DSO if needed */
857 if (v[0] > (size_t)self->dtv[0]) {
858 void **newdtv = p->new_dtv +
859 (v[0]+1)*sizeof(void *)*a_fetch_add(&p->new_dtv_idx,1);
860 memcpy(newdtv, self->dtv,
861 ((size_t)self->dtv[0]+1) * sizeof(void *));
862 newdtv[0] = (void *)v[0];
866 /* Get new TLS memory from new DSO */
867 unsigned char *mem = p->new_tls +
868 (p->tls_size + p->tls_align) * a_fetch_add(&p->new_tls_idx,1);
869 mem += ((uintptr_t)p->tls_image - (uintptr_t)mem) & (p->tls_align-1);
870 self->dtv[v[0]] = mem;
871 memcpy(mem, p->tls_image, p->tls_len);
872 pthread_sigmask(SIG_SETMASK, &set, 0);
876 static void update_tls_size()
878 libc.tls_size = ALIGN(
879 (1+tls_cnt) * sizeof(void *) +
881 sizeof(struct pthread) +
886 void *__dynlink(int argc, char **argv)
888 size_t aux[AUX_CNT] = {0};
892 static struct dso builtin_dsos[3];
893 struct dso *const app = builtin_dsos+0;
894 struct dso *const lib = builtin_dsos+1;
895 struct dso *const vdso = builtin_dsos+2;
899 char **envp = argv+argc+1;
901 /* Find aux vector just past environ[] */
902 for (i=argc+1; argv[i]; i++)
903 if (!memcmp(argv[i], "LD_LIBRARY_PATH=", 16))
904 env_path = argv[i]+16;
905 else if (!memcmp(argv[i], "LD_PRELOAD=", 11))
906 env_preload = argv[i]+11;
907 auxv = (void *)(argv+i+1);
909 decode_vec(auxv, aux, AUX_CNT);
911 /* Only trust user/env if kernel says we're not suid/sgid */
912 if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
913 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]) {
918 /* If the dynamic linker was invoked as a program itself, AT_BASE
919 * will not be set. In that case, we assume the base address is
920 * the start of the page containing the PHDRs; I don't know any
921 * better approach... */
923 aux[AT_BASE] = aux[AT_PHDR] & -PAGE_SIZE;
924 aux[AT_PHDR] = aux[AT_PHENT] = aux[AT_PHNUM] = 0;
927 /* The dynamic linker load address is passed by the kernel
928 * in the AUX vector, so this is easy. */
929 lib->base = (void *)aux[AT_BASE];
930 lib->name = lib->shortname = "libc.so";
932 ehdr = (void *)lib->base;
933 lib->phnum = ehdr->e_phnum;
934 lib->phdr = (void *)(aux[AT_BASE]+ehdr->e_phoff);
935 find_map_range(lib->phdr, ehdr->e_phnum, ehdr->e_phentsize, lib);
936 lib->dynv = (void *)(lib->base + find_dyn(lib->phdr,
937 ehdr->e_phnum, ehdr->e_phentsize));
941 size_t interp_off = 0;
942 size_t tls_image = 0;
943 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
944 app->phdr = phdr = (void *)aux[AT_PHDR];
945 app->phnum = aux[AT_PHNUM];
946 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
947 if (phdr->p_type == PT_PHDR)
948 app->base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
949 else if (phdr->p_type == PT_INTERP)
950 interp_off = (size_t)phdr->p_vaddr;
951 else if (phdr->p_type == PT_TLS) {
952 tls_image = phdr->p_vaddr;
953 app->tls_len = phdr->p_filesz;
954 app->tls_size = phdr->p_memsz;
955 app->tls_align = phdr->p_align;
958 if (app->tls_size) app->tls_image = (char *)app->base + tls_image;
959 if (interp_off) lib->name = (char *)app->base + interp_off;
961 app->dynv = (void *)(app->base + find_dyn(
962 (void *)aux[AT_PHDR], aux[AT_PHNUM], aux[AT_PHENT]));
963 find_map_range((void *)aux[AT_PHDR],
964 aux[AT_PHNUM], aux[AT_PHENT], app);
967 char *ldname = argv[0];
968 size_t l = strlen(ldname);
969 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
970 *argv++ = (void *)-1;
971 if (argv[0] && !strcmp(argv[0], "--")) *argv++ = (void *)-1;
973 dprintf(2, "musl libc/dynamic program loader\n");
974 dprintf(2, "usage: %s pathname%s\n", ldname,
975 ldd_mode ? "" : " [args]");
978 fd = open(argv[0], O_RDONLY);
980 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
984 ehdr = (void *)map_library(fd, app);
986 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
993 aux[AT_ENTRY] = (size_t)app->base + ehdr->e_entry;
994 /* Find the name that would have been used for the dynamic
995 * linker had ldd not taken its place. */
997 for (i=0; i<app->phnum; i++) {
998 if (app->phdr[i].p_type == PT_INTERP)
999 lib->name = (void *)(app->base
1000 + app->phdr[i].p_vaddr);
1002 dprintf(1, "\t%s (%p)\n", lib->name, lib->base);
1005 if (app->tls_size) {
1006 app->tls_id = tls_cnt = 1;
1008 app->tls_offset = 0;
1009 tls_offset = app->tls_size
1010 + ( -((uintptr_t)app->tls_image + app->tls_size)
1011 & (app->tls_align-1) );
1013 tls_offset = app->tls_offset = app->tls_size
1014 + ( -((uintptr_t)app->tls_image + app->tls_size)
1015 & (app->tls_align-1) );
1017 tls_align = MAXP2(tls_align, app->tls_align);
1022 /* Attach to vdso, if provided by the kernel */
1023 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
1024 ehdr = (void *)vdso_base;
1025 vdso->phdr = phdr = (void *)(vdso_base + ehdr->e_phoff);
1026 vdso->phnum = ehdr->e_phnum;
1027 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1028 if (phdr->p_type == PT_DYNAMIC)
1029 vdso->dynv = (void *)(vdso_base + phdr->p_offset);
1030 if (phdr->p_type == PT_LOAD)
1031 vdso->base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1034 vdso->shortname = "linux-gate.so.1";
1041 /* Initial dso chain consists only of the app. We temporarily
1042 * append the dynamic linker/libc so we can relocate it, then
1043 * restore the initial chain in preparation for loading third
1044 * party libraries (preload/needed). */
1051 /* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */
1053 /* Donate unused parts of app and library mapping to malloc */
1054 reclaim_gaps(app->base, (void *)aux[AT_PHDR], aux[AT_PHENT], aux[AT_PHNUM]);
1055 ehdr = (void *)lib->base;
1056 reclaim_gaps(lib->base, (void *)(lib->base+ehdr->e_phoff),
1057 ehdr->e_phentsize, ehdr->e_phnum);
1059 /* Load preload/needed libraries, add their symbols to the global
1060 * namespace, and perform all remaining relocations. The main
1061 * program must be relocated LAST since it may contain copy
1062 * relocations which depend on libraries' relocations. */
1063 if (env_preload) load_preload(env_preload);
1067 reloc_all(app->next);
1072 void *mem = mmap(0, libc.tls_size, PROT_READ|PROT_WRITE,
1073 MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
1074 if (mem==MAP_FAILED ||
1075 !__install_initial_tls(__copy_tls(mem))) {
1076 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1077 argv[0], libc.tls_size);
1082 if (ldso_fail) _exit(127);
1083 if (ldd_mode) _exit(0);
1085 /* Switch to runtime mode: any further failures in the dynamic
1086 * linker are a reportable failure rather than a fatal startup
1087 * error. If the dynamic loader (dlopen) will not be used, free
1088 * all memory used by the dynamic linker. */
1091 #ifndef DYNAMIC_IS_RO
1092 for (i=0; app->dynv[i]; i+=2)
1093 if (app->dynv[i]==DT_DEBUG)
1094 app->dynv[i+1] = (size_t)&debug;
1097 debug.bp = _dl_debug_state;
1099 debug.base = lib->base;
1103 if (ssp_used) __init_ssp((void *)aux[AT_RANDOM]);
1104 __init_libc(envp, argv[0]);
1109 return (void *)aux[AT_ENTRY];
1112 void *dlopen(const char *file, int mode)
1114 struct dso *volatile p, *orig_tail, *next;
1115 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1120 if (!file) return head;
1122 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1123 pthread_rwlock_wrlock(&lock);
1127 orig_tls_cnt = tls_cnt;
1128 orig_tls_offset = tls_offset;
1129 orig_tls_align = tls_align;
1131 noload = mode & RTLD_NOLOAD;
1134 if (setjmp(*rtld_fail)) {
1135 /* Clean up anything new that was (partially) loaded */
1136 if (p && p->deps) for (i=0; p->deps[i]; i++)
1137 if (p->deps[i]->global < 0)
1138 p->deps[i]->global = 0;
1139 for (p=orig_tail->next; p; p=next) {
1141 munmap(p->map, p->map_len);
1145 tls_cnt = orig_tls_cnt;
1146 tls_offset = orig_tls_offset;
1147 tls_align = orig_tls_align;
1153 } else p = load_library(file);
1156 snprintf(errbuf, sizeof errbuf, noload ?
1157 "Library %s is not already loaded" :
1158 "Error loading shared library %s: %m",
1164 /* First load handling */
1167 if (p->deps) for (i=0; p->deps[i]; i++)
1168 if (!p->deps[i]->global)
1169 p->deps[i]->global = -1;
1170 if (!p->global) p->global = -1;
1172 if (p->deps) for (i=0; p->deps[i]; i++)
1173 if (p->deps[i]->global < 0)
1174 p->deps[i]->global = 0;
1175 if (p->global < 0) p->global = 0;
1178 if (mode & RTLD_GLOBAL) {
1179 if (p->deps) for (i=0; p->deps[i]; i++)
1180 p->deps[i]->global = 1;
1186 if (ssp_used) __init_ssp(libc.auxv);
1193 pthread_rwlock_unlock(&lock);
1194 if (p) do_init_fini(orig_tail);
1195 pthread_setcancelstate(cs, 0);
1199 static int invalid_dso_handle(void *h)
1202 for (p=head; p; p=p->next) if (h==p) return 0;
1203 snprintf(errbuf, sizeof errbuf, "Invalid library handle %p", (void *)h);
1208 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1211 uint32_t h = 0, gh = 0;
1213 if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1214 if (p == RTLD_DEFAULT) {
1216 } else if (p == RTLD_NEXT) {
1217 for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
1221 struct symdef def = find_sym(p, s, 0);
1222 if (!def.sym) goto failed;
1223 if ((def.sym->st_info&0xf) == STT_TLS)
1224 return __tls_get_addr((size_t []){def.dso->tls_id, def.sym->st_value});
1225 return def.dso->base + def.sym->st_value;
1227 if (p != RTLD_DEFAULT && p != RTLD_NEXT && invalid_dso_handle(p))
1231 sym = gnu_lookup(s, gh, p);
1234 sym = sysv_lookup(s, h, p);
1236 if (sym && (sym->st_info&0xf) == STT_TLS)
1237 return __tls_get_addr((size_t []){p->tls_id, sym->st_value});
1238 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1239 return p->base + sym->st_value;
1240 if (p->deps) for (i=0; p->deps[i]; i++) {
1241 if (p->deps[i]->ghashtab) {
1242 if (!gh) gh = gnu_hash(s);
1243 sym = gnu_lookup(s, gh, p->deps[i]);
1245 if (!h) h = sysv_hash(s);
1246 sym = sysv_lookup(s, h, p->deps[i]);
1248 if (sym && (sym->st_info&0xf) == STT_TLS)
1249 return __tls_get_addr((size_t []){p->deps[i]->tls_id, sym->st_value});
1250 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1251 return p->deps[i]->base + sym->st_value;
1255 snprintf(errbuf, sizeof errbuf, "Symbol not found: %s", s);
1259 int __dladdr(void *addr, Dl_info *info)
1269 pthread_rwlock_rdlock(&lock);
1270 for (p=head; p && (unsigned char *)addr-p->map>p->map_len; p=p->next);
1271 pthread_rwlock_unlock(&lock);
1276 strings = p->strings;
1278 nsym = p->hashtab[1];
1282 buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
1283 sym += p->ghashtab[1];
1284 for (i = 0; i < p->ghashtab[0]; i++) {
1285 if (buckets[i] > nsym)
1289 nsym -= p->ghashtab[1];
1290 hashval = buckets + p->ghashtab[0] + nsym;
1292 while (!(*hashval++ & 1));
1296 for (; nsym; nsym--, sym++) {
1298 && (1<<(sym->st_info&0xf) & OK_TYPES)
1299 && (1<<(sym->st_info>>4) & OK_BINDS)) {
1300 void *symaddr = p->base + sym->st_value;
1301 if (symaddr > addr || symaddr < best)
1304 bestname = strings + sym->st_name;
1305 if (addr == symaddr)
1310 if (!best) return 0;
1312 info->dli_fname = p->name;
1313 info->dli_fbase = p->base;
1314 info->dli_sname = bestname;
1315 info->dli_saddr = best;
1320 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1323 pthread_rwlock_rdlock(&lock);
1324 res = do_dlsym(p, s, ra);
1325 pthread_rwlock_unlock(&lock);
1329 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
1331 struct dso *current;
1332 struct dl_phdr_info info;
1334 for(current = head; current;) {
1335 info.dlpi_addr = (uintptr_t)current->base;
1336 info.dlpi_name = current->name;
1337 info.dlpi_phdr = current->phdr;
1338 info.dlpi_phnum = current->phnum;
1339 info.dlpi_adds = gencnt;
1341 info.dlpi_tls_modid = current->tls_id;
1342 info.dlpi_tls_data = current->tls_image;
1344 ret = (callback)(&info, sizeof (info), data);
1346 if (ret != 0) break;
1348 pthread_rwlock_rdlock(&lock);
1349 current = current->next;
1350 pthread_rwlock_unlock(&lock);
1355 static int invalid_dso_handle(void *h)
1357 snprintf(errbuf, sizeof errbuf, "Invalid library handle %p", (void *)h);
1361 void *dlopen(const char *file, int mode)
1365 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1369 int __dladdr (void *addr, Dl_info *info)
1375 int __dlinfo(void *dso, int req, void *res)
1377 if (invalid_dso_handle(dso)) return -1;
1378 if (req != RTLD_DI_LINKMAP) {
1379 snprintf(errbuf, sizeof errbuf, "Unsupported request %d", req);
1383 *(struct link_map **)res = dso;
1389 if (!errflag) return 0;
1394 int dlclose(void *p)
1396 return invalid_dso_handle(p);