20 #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;
74 size_t tls_len, tls_size, tls_align, tls_id, tls_offset;
76 unsigned char *new_tls;
77 int new_dtv_idx, new_tls_idx;
78 struct dso *fini_next;
90 void __init_ssp(size_t *);
91 void *__install_initial_tls(void *);
93 static struct dso *head, *tail, *libc, *fini_head;
94 static char *env_path, *sys_path, *r_path;
99 static jmp_buf rtld_fail;
100 static pthread_rwlock_t lock;
101 static struct debug debug;
103 static size_t tls_cnt, tls_offset, tls_start, tls_align = 4*sizeof(size_t);
104 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
106 struct debug *_dl_debug_addr = &debug;
111 static void decode_vec(size_t *v, size_t *a, size_t cnt)
113 memset(a, 0, cnt*sizeof(size_t));
114 for (; v[0]; v+=2) if (v[0]<cnt) {
120 static int search_vec(size_t *v, size_t *r, size_t key)
122 for (; v[0]!=key; v+=2)
128 static uint32_t sysv_hash(const char *s0)
130 const unsigned char *s = (void *)s0;
136 return h & 0xfffffff;
139 static uint32_t gnu_hash(const char *s0)
141 const unsigned char *s = (void *)s0;
142 uint_fast32_t h = 5381;
148 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
151 Sym *syms = dso->syms;
152 uint32_t *hashtab = dso->hashtab;
153 char *strings = dso->strings;
154 for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
155 if (!strcmp(s, strings+syms[i].st_name))
161 static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso)
165 uint32_t *hashtab = dso->ghashtab;
166 uint32_t nbuckets = hashtab[0];
167 uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
170 uint32_t n = buckets[h1 % nbuckets];
174 strings = dso->strings;
176 hashval = buckets + nbuckets + (n - hashtab[1]);
178 for (h1 |= 1; ; sym++) {
180 if ((h1 == (h2|1)) && !strcmp(s, strings + sym->st_name))
188 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
189 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK)
191 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
193 uint32_t h = 0, gh = 0;
194 struct symdef def = {0};
197 if (gh == 0x1f4039c9 && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
200 if (h == 0x595a4cc && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
202 for (; dso; dso=dso->next) {
204 if (!dso->global) continue;
206 if (!gh) gh = gnu_hash(s);
207 sym = gnu_lookup(s, gh, dso);
209 if (!h) h = sysv_hash(s);
210 sym = sysv_lookup(s, h, dso);
214 if (need_def || (sym->st_info&0xf) == STT_TLS)
217 if ((sym->st_info&0xf) != STT_TLS)
219 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
220 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
222 if (def.sym && sym->st_info>>4 == STB_WEAK) continue;
225 if (sym->st_info>>4 == STB_GLOBAL) break;
230 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
232 unsigned char *base = dso->base;
233 Sym *syms = dso->syms;
234 char *strings = dso->strings;
242 for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
243 type = R_TYPE(rel[1]);
244 sym_index = R_SYM(rel[1]);
246 sym = syms + sym_index;
247 name = strings + sym->st_name;
248 ctx = IS_COPY(type) ? head->next : head;
249 def = find_sym(ctx, name, IS_PLT(type));
250 if (!def.sym && sym->st_info>>4 != STB_WEAK) {
251 snprintf(errbuf, sizeof errbuf,
252 "Error relocating %s: %s: symbol not found",
254 if (runtime) longjmp(rtld_fail, 1);
255 dprintf(2, "%s\n", errbuf);
264 do_single_reloc(dso, base, (void *)(base + rel[0]), type,
265 stride>2 ? rel[2] : 0, sym, sym?sym->st_size:0, def,
266 def.sym?(size_t)(def.dso->base+def.sym->st_value):0);
270 /* A huge hack: to make up for the wastefulness of shared libraries
271 * needing at least a page of dirty memory even if they have no global
272 * data, we reclaim the gaps at the beginning and end of writable maps
273 * and "donate" them to the heap by setting up minimal malloc
274 * structures and then freeing them. */
276 static void reclaim(unsigned char *base, size_t start, size_t end)
279 start = start + 6*sizeof(size_t)-1 & -4*sizeof(size_t);
280 end = (end & -4*sizeof(size_t)) - 2*sizeof(size_t);
281 if (start>end || end-start < 4*sizeof(size_t)) return;
282 a = (size_t *)(base + start);
283 z = (size_t *)(base + end);
285 a[-1] = z[0] = end-start + 2*sizeof(size_t) | 1;
290 static void reclaim_gaps(unsigned char *base, Phdr *ph, size_t phent, size_t phcnt)
292 for (; phcnt--; ph=(void *)((char *)ph+phent)) {
293 if (ph->p_type!=PT_LOAD) continue;
294 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
295 reclaim(base, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
296 reclaim(base, ph->p_vaddr+ph->p_memsz,
297 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
301 static void *map_library(int fd, struct dso *dso)
303 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
305 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
306 size_t this_min, this_max;
311 unsigned char *map, *base;
316 ssize_t l = read(fd, buf, sizeof buf);
317 if (l<sizeof *eh) return 0;
319 phsize = eh->e_phentsize * eh->e_phnum;
320 if (phsize + sizeof *eh > l) return 0;
321 if (eh->e_phoff + phsize > l) {
322 l = pread(fd, buf+1, phsize, eh->e_phoff);
323 if (l != phsize) return 0;
324 eh->e_phoff = sizeof *eh;
326 ph = (void *)((char *)buf + eh->e_phoff);
327 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
328 if (ph->p_type == PT_DYNAMIC)
330 if (ph->p_type == PT_TLS) {
331 tls_image = ph->p_vaddr;
332 dso->tls_align = ph->p_align;
333 dso->tls_len = ph->p_filesz;
334 dso->tls_size = ph->p_memsz;
336 if (ph->p_type != PT_LOAD) continue;
337 if (ph->p_vaddr < addr_min) {
338 addr_min = ph->p_vaddr;
339 off_start = ph->p_offset;
340 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
341 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
342 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
344 if (ph->p_vaddr+ph->p_memsz > addr_max) {
345 addr_max = ph->p_vaddr+ph->p_memsz;
349 addr_max += PAGE_SIZE-1;
350 addr_max &= -PAGE_SIZE;
351 addr_min &= -PAGE_SIZE;
352 off_start &= -PAGE_SIZE;
353 map_len = addr_max - addr_min + off_start;
354 /* The first time, we map too much, possibly even more than
355 * the length of the file. This is okay because we will not
356 * use the invalid part; we just need to reserve the right
357 * amount of virtual address space to map over later. */
358 map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start);
359 if (map==MAP_FAILED) return 0;
360 base = map - addr_min;
361 ph = (void *)((char *)buf + eh->e_phoff);
362 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
363 if (ph->p_type != PT_LOAD) continue;
364 /* Reuse the existing mapping for the lowest-address LOAD */
365 if ((ph->p_vaddr & -PAGE_SIZE) == addr_min) continue;
366 this_min = ph->p_vaddr & -PAGE_SIZE;
367 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
368 off_start = ph->p_offset & -PAGE_SIZE;
369 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
370 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
371 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
372 if (mmap(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
374 if (ph->p_memsz > ph->p_filesz) {
375 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
376 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
377 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
378 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)
382 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
383 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
384 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC) < 0)
388 if (!runtime) reclaim_gaps(base, (void *)((char *)buf + eh->e_phoff),
389 eh->e_phentsize, eh->e_phnum);
391 dso->map_len = map_len;
393 dso->dynv = (void *)(base+dyn);
394 if (dso->tls_size) dso->tls_image = (void *)(base+tls_image);
397 munmap(map, map_len);
401 static int path_open(const char *name, const char *search, char *buf, size_t buf_size)
403 const char *s=search, *z;
409 l = z ? z-s : strlen(s);
410 snprintf(buf, buf_size, "%.*s/%s", l, s, name);
411 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
416 static void decode_dyn(struct dso *p)
418 size_t dyn[DYN_CNT] = {0};
419 decode_vec(p->dynv, dyn, DYN_CNT);
420 p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
421 p->strings = (void *)(p->base + dyn[DT_STRTAB]);
422 if (dyn[0]&(1<<DT_HASH))
423 p->hashtab = (void *)(p->base + dyn[DT_HASH]);
424 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
425 p->ghashtab = (void *)(p->base + *dyn);
428 static struct dso *load_library(const char *name)
430 char buf[2*NAME_MAX+2];
431 const char *pathname;
432 unsigned char *base, *map;
433 size_t dyno, map_len;
434 struct dso *p, temp_dso = {0};
440 /* Catch and block attempts to reload the implementation itself */
441 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
442 static const char *rp, reserved[] =
443 "c\0pthread\0rt\0m\0dl\0util\0xnet\0";
444 char *z = strchr(name, '.');
447 for (rp=reserved; *rp && memcmp(name+3, rp, l-3); rp+=strlen(rp)+1);
452 tail = libc->next ? libc->next : libc;
458 if (strchr(name, '/')) {
460 fd = open(name, O_RDONLY|O_CLOEXEC);
462 /* Search for the name to see if it's already loaded */
463 for (p=head->next; p; p=p->next) {
464 if (p->shortname && !strcmp(p->shortname, name)) {
469 if (strlen(name) > NAME_MAX) return 0;
471 if (r_path) fd = path_open(name, r_path, buf, sizeof buf);
472 if (fd < 0 && env_path) fd = path_open(name, env_path, buf, sizeof buf);
475 FILE *f = fopen(ETC_LDSO_PATH, "rbe");
477 if (getline(&sys_path, (size_t[1]){0}, f) > 0)
478 sys_path[strlen(sys_path)-1]=0;
482 if (sys_path) fd = path_open(name, sys_path, buf, sizeof buf);
483 else fd = path_open(name, "/lib:/usr/local/lib:/usr/lib", buf, sizeof buf);
487 if (fd < 0) return 0;
488 if (fstat(fd, &st) < 0) {
492 for (p=head->next; p; p=p->next) {
493 if (p->dev == st.st_dev && p->ino == st.st_ino) {
494 /* If this library was previously loaded with a
495 * pathname but a search found the same inode,
496 * setup its shortname so it can be found by name. */
497 if (!p->shortname && pathname != name)
498 p->shortname = strrchr(p->name, '/')+1;
504 map = map_library(fd, &temp_dso);
508 /* Allocate storage for the new DSO. When there is TLS, this
509 * storage must include a reservation for all pre-existing
510 * threads to obtain copies of both the new TLS, and an
511 * extended DTV capable of storing an additional slot for
512 * the newly-loaded DSO. */
513 alloc_size = sizeof *p + strlen(pathname) + 1;
514 if (runtime && temp_dso.tls_image) {
515 size_t per_th = temp_dso.tls_size + temp_dso.tls_align
516 + sizeof(void *) * (tls_cnt+3);
517 n_th = __libc.threads_minus_1 + 1;
518 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
519 else alloc_size += n_th * per_th;
521 p = calloc(1, alloc_size);
523 munmap(map, map_len);
526 memcpy(p, &temp_dso, sizeof temp_dso);
532 strcpy(p->name, pathname);
533 /* Add a shortname only if name arg was not an explicit pathname. */
534 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
536 if (runtime && !__pthread_self_init()) {
538 munmap(map, map_len);
541 p->tls_id = ++tls_cnt;
542 tls_align = MAXP2(tls_align, p->tls_align);
543 tls_offset += p->tls_size + p->tls_align - 1;
544 tls_offset -= (tls_offset + (uintptr_t)p->tls_image)
546 p->tls_offset = tls_offset;
547 p->new_dtv = (void *)(-sizeof(size_t) &
548 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
549 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
556 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, base);
561 static void load_deps(struct dso *p)
564 struct dso ***deps = &p->deps, **tmp, *dep;
565 for (; p; p=p->next) {
566 for (i=0; p->dynv[i]; i+=2) {
567 if (p->dynv[i] != DT_RPATH) continue;
568 r_path = (void *)(p->strings + p->dynv[i+1]);
570 for (i=0; p->dynv[i]; i+=2) {
571 if (p->dynv[i] != DT_NEEDED) continue;
572 dep = load_library(p->strings + p->dynv[i+1]);
574 snprintf(errbuf, sizeof errbuf,
575 "Error loading shared library %s: %m (needed by %s)",
576 p->strings + p->dynv[i+1], p->name);
577 if (runtime) longjmp(rtld_fail, 1);
578 dprintf(2, "%s\n", errbuf);
583 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
584 if (!tmp) longjmp(rtld_fail, 1);
594 static void load_preload(char *s)
599 for ( ; *s && isspace(*s); s++);
600 for (z=s; *z && !isspace(*z); z++);
608 static void make_global(struct dso *p)
610 for (; p; p=p->next) p->global = 1;
613 static void reloc_all(struct dso *p)
615 size_t dyn[DYN_CNT] = {0};
616 for (; p; p=p->next) {
617 if (p->relocated) continue;
618 decode_vec(p->dynv, dyn, DYN_CNT);
619 #ifdef NEED_ARCH_RELOCS
620 do_arch_relocs(p, head);
622 do_relocs(p, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
623 2+(dyn[DT_PLTREL]==DT_RELA));
624 do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2);
625 do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
630 static void free_all(struct dso *p)
635 if (p->map && p!=libc && p!=head) free(p);
640 static size_t find_dyn(Phdr *ph, size_t cnt, size_t stride)
642 for (; cnt--; ph = (void *)((char *)ph + stride))
643 if (ph->p_type == PT_DYNAMIC)
648 static void find_map_range(Phdr *ph, size_t cnt, size_t stride, struct dso *p)
650 size_t min_addr = -1, max_addr = 0;
651 for (; cnt--; ph = (void *)((char *)ph + stride)) {
652 if (ph->p_type != PT_LOAD) continue;
653 if (ph->p_vaddr < min_addr)
654 min_addr = ph->p_vaddr;
655 if (ph->p_vaddr+ph->p_memsz > max_addr)
656 max_addr = ph->p_vaddr+ph->p_memsz;
658 min_addr &= -PAGE_SIZE;
659 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
660 p->map = p->base + min_addr;
661 p->map_len = max_addr - min_addr;
664 static void do_fini()
667 size_t dyn[DYN_CNT] = {0};
668 for (p=fini_head; p; p=p->fini_next) {
669 if (!p->constructed) continue;
670 decode_vec(p->dynv, dyn, DYN_CNT);
671 ((void (*)(void))(p->base + dyn[DT_FINI]))();
675 static void do_init_fini(struct dso *p)
677 size_t dyn[DYN_CNT] = {0};
678 int need_locking = __libc.threads_minus_1;
679 /* Allow recursive calls that arise when a library calls
680 * dlopen from one of its constructors, but block any
681 * other threads until all ctors have finished. */
682 if (need_locking) pthread_mutex_lock(&init_fini_lock);
683 for (; p; p=p->prev) {
684 if (p->constructed) continue;
686 decode_vec(p->dynv, dyn, DYN_CNT);
687 if (dyn[0] & (1<<DT_FINI)) {
688 p->fini_next = fini_head;
691 if (dyn[0] & (1<<DT_INIT))
692 ((void (*)(void))(p->base + dyn[DT_INIT]))();
694 if (need_locking) pthread_mutex_unlock(&init_fini_lock);
697 void _dl_debug_state(void)
701 void *__copy_tls(unsigned char *mem)
706 if (!tls_cnt) return mem;
708 void **dtv = (void *)mem;
709 dtv[0] = (void *)tls_cnt;
711 mem += __libc.tls_size - sizeof(struct pthread);
712 mem -= (uintptr_t)mem & (tls_align-1);
716 for (p=head; p; p=p->next) {
717 if (!p->tls_id) continue;
718 dtv[p->tls_id] = mem - p->tls_offset;
719 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
725 void *__tls_get_addr(size_t *v)
727 pthread_t self = __pthread_self();
728 if (self->dtv && v[0]<=(size_t)self->dtv[0] && self->dtv[v[0]])
729 return (char *)self->dtv[v[0]]+v[1];
731 /* Block signals to make accessing new TLS async-signal-safe */
733 pthread_sigmask(SIG_BLOCK, SIGALL_SET, &set);
734 if (self->dtv && v[0]<=(size_t)self->dtv[0] && self->dtv[v[0]]) {
735 pthread_sigmask(SIG_SETMASK, &set, 0);
736 return (char *)self->dtv[v[0]]+v[1];
739 /* This is safe without any locks held because, if the caller
740 * is able to request the Nth entry of the DTV, the DSO list
741 * must be valid at least that far out and it was synchronized
742 * at program startup or by an already-completed call to dlopen. */
744 for (p=head; p->tls_id != v[0]; p=p->next);
746 /* Get new DTV space from new DSO if needed */
747 if (!self->dtv || v[0] > (size_t)self->dtv[0]) {
748 void **newdtv = p->new_dtv +
749 (v[0]+1)*sizeof(void *)*a_fetch_add(&p->new_dtv_idx,1);
750 if (self->dtv) memcpy(newdtv, self->dtv,
751 ((size_t)self->dtv[0]+1) * sizeof(void *));
752 newdtv[0] = (void *)v[0];
756 /* Get new TLS memory from new DSO */
757 unsigned char *mem = p->new_tls +
758 (p->tls_size + p->tls_align) * a_fetch_add(&p->new_tls_idx,1);
759 mem += ((uintptr_t)p->tls_image - (uintptr_t)mem) & (p->tls_align-1);
760 self->dtv[v[0]] = mem;
761 memcpy(mem, p->tls_image, p->tls_len);
762 pthread_sigmask(SIG_SETMASK, &set, 0);
766 static void update_tls_size()
768 size_t below_tp = (1+tls_cnt) * sizeof(void *) + tls_offset;
769 size_t above_tp = sizeof(struct pthread) + tls_start + tls_align;
770 __libc.tls_size = ALIGN(below_tp + above_tp, tls_align);
773 void *__dynlink(int argc, char **argv)
775 size_t aux[AUX_CNT] = {0};
779 static struct dso builtin_dsos[3];
780 struct dso *const app = builtin_dsos+0;
781 struct dso *const lib = builtin_dsos+1;
782 struct dso *const vdso = builtin_dsos+2;
786 /* Find aux vector just past environ[] */
787 for (i=argc+1; argv[i]; i++)
788 if (!memcmp(argv[i], "LD_LIBRARY_PATH=", 16))
789 env_path = argv[i]+16;
790 else if (!memcmp(argv[i], "LD_PRELOAD=", 11))
791 env_preload = argv[i]+11;
792 auxv = (void *)(argv+i+1);
794 decode_vec(auxv, aux, AUX_CNT);
796 /* Only trust user/env if kernel says we're not suid/sgid */
797 if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
798 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]) {
803 /* If the dynamic linker was invoked as a program itself, AT_BASE
804 * will not be set. In that case, we assume the base address is
805 * the start of the page containing the PHDRs; I don't know any
806 * better approach... */
808 aux[AT_BASE] = aux[AT_PHDR] & -PAGE_SIZE;
809 aux[AT_PHDR] = aux[AT_PHENT] = aux[AT_PHNUM] = 0;
812 /* The dynamic linker load address is passed by the kernel
813 * in the AUX vector, so this is easy. */
814 lib->base = (void *)aux[AT_BASE];
815 lib->name = lib->shortname = "libc.so";
817 ehdr = (void *)lib->base;
818 find_map_range((void *)(aux[AT_BASE]+ehdr->e_phoff),
819 ehdr->e_phnum, ehdr->e_phentsize, lib);
820 lib->dynv = (void *)(lib->base + find_dyn(
821 (void *)(aux[AT_BASE]+ehdr->e_phoff),
822 ehdr->e_phnum, ehdr->e_phentsize));
826 size_t interp_off = 0;
827 size_t tls_image = 0;
828 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
829 phdr = (void *)aux[AT_PHDR];
830 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
831 if (phdr->p_type == PT_PHDR)
832 app->base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
833 else if (phdr->p_type == PT_INTERP)
834 interp_off = (size_t)phdr->p_vaddr;
835 else if (phdr->p_type == PT_TLS) {
836 tls_image = phdr->p_vaddr;
837 app->tls_len = phdr->p_filesz;
838 app->tls_size = phdr->p_memsz;
839 app->tls_align = phdr->p_align;
842 if (app->tls_size) app->tls_image = (char *)app->base + tls_image;
843 if (interp_off) lib->name = (char *)app->base + interp_off;
845 app->dynv = (void *)(app->base + find_dyn(
846 (void *)aux[AT_PHDR], aux[AT_PHNUM], aux[AT_PHENT]));
847 find_map_range((void *)aux[AT_PHDR],
848 aux[AT_PHNUM], aux[AT_PHENT], app);
851 char *ldname = argv[0];
852 size_t dyno, l = strlen(ldname);
853 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
854 *argv++ = (void *)-1;
855 if (argv[0] && !strcmp(argv[0], "--")) *argv++ = (void *)-1;
857 dprintf(2, "musl libc/dynamic program loader\n");
858 dprintf(2, "usage: %s pathname%s\n", ldname,
859 ldd_mode ? "" : " [args]");
862 fd = open(argv[0], O_RDONLY);
864 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
868 ehdr = (void *)map_library(fd, app);
870 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
877 aux[AT_ENTRY] = ehdr->e_entry;
880 app->tls_id = tls_cnt = 1;
881 tls_offset = app->tls_offset = app->tls_size;
882 tls_start = -((uintptr_t)app->tls_image + app->tls_size)
883 & (app->tls_align-1);
884 tls_align = MAXP2(tls_align, app->tls_align);
887 app->constructed = 1;
890 /* Attach to vdso, if provided by the kernel */
891 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
892 ehdr = (void *)vdso_base;
893 phdr = (void *)(vdso_base + ehdr->e_phoff);
894 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
895 if (phdr->p_type == PT_DYNAMIC)
896 vdso->dynv = (void *)(vdso_base + phdr->p_offset);
897 if (phdr->p_type == PT_LOAD)
898 vdso->base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
900 vdso->name = vdso->shortname = "linux-gate.so.1";
907 /* Initial dso chain consists only of the app. We temporarily
908 * append the dynamic linker/libc so we can relocate it, then
909 * restore the initial chain in preparation for loading third
910 * party libraries (preload/needed). */
917 /* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */
919 /* Donate unused parts of app and library mapping to malloc */
920 reclaim_gaps(app->base, (void *)aux[AT_PHDR], aux[AT_PHENT], aux[AT_PHNUM]);
921 ehdr = (void *)lib->base;
922 reclaim_gaps(lib->base, (void *)(lib->base+ehdr->e_phoff),
923 ehdr->e_phentsize, ehdr->e_phnum);
925 /* Load preload/needed libraries, add their symbols to the global
926 * namespace, and perform all remaining relocations. The main
927 * program must be relocated LAST since it may contain copy
928 * relocations which depend on libraries' relocations. */
929 if (env_preload) load_preload(env_preload);
933 reloc_all(app->next);
939 void *mem = mmap(0, __libc.tls_size, PROT_READ|PROT_WRITE,
940 MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
941 if (mem==MAP_FAILED ||
942 !__install_initial_tls(__copy_tls(mem))) {
943 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
944 argv[0], __libc.tls_size);
949 if (ldso_fail) _exit(127);
950 if (ldd_mode) _exit(0);
952 /* Switch to runtime mode: any further failures in the dynamic
953 * linker are a reportable failure rather than a fatal startup
954 * error. If the dynamic loader (dlopen) will not be used, free
955 * all memory used by the dynamic linker. */
958 #ifndef DYNAMIC_IS_RO
959 for (i=0; app->dynv[i]; i+=2)
960 if (app->dynv[i]==DT_DEBUG)
961 app->dynv[i+1] = (size_t)&debug;
964 debug.bp = _dl_debug_state;
966 debug.base = lib->base;
970 if (ssp_used) __init_ssp(auxv);
976 return (void *)aux[AT_ENTRY];
979 void *dlopen(const char *file, int mode)
981 struct dso *volatile p, *orig_tail, *next;
982 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
986 if (!file) return head;
988 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
989 pthread_rwlock_wrlock(&lock);
993 orig_tls_cnt = tls_cnt;
994 orig_tls_offset = tls_offset;
995 orig_tls_align = tls_align;
998 if (setjmp(rtld_fail)) {
999 /* Clean up anything new that was (partially) loaded */
1000 if (p && p->deps) for (i=0; p->deps[i]; i++)
1001 if (p->deps[i]->global < 0)
1002 p->deps[i]->global = 0;
1003 for (p=orig_tail->next; p; p=next) {
1005 munmap(p->map, p->map_len);
1009 tls_cnt = orig_tls_cnt;
1010 tls_offset = orig_tls_offset;
1011 tls_align = orig_tls_align;
1017 } else p = load_library(file);
1020 snprintf(errbuf, sizeof errbuf,
1021 "Error loading shared library %s: %m", file);
1026 /* First load handling */
1029 if (p->deps) for (i=0; p->deps[i]; i++)
1030 if (!p->deps[i]->global)
1031 p->deps[i]->global = -1;
1032 if (!p->global) p->global = -1;
1034 if (p->deps) for (i=0; p->deps[i]; i++)
1035 if (p->deps[i]->global < 0)
1036 p->deps[i]->global = 0;
1037 if (p->global < 0) p->global = 0;
1040 if (mode & RTLD_GLOBAL) {
1041 if (p->deps) for (i=0; p->deps[i]; i++)
1042 p->deps[i]->global = 1;
1048 if (ssp_used) __init_ssp(auxv);
1054 pthread_rwlock_unlock(&lock);
1055 if (p) do_init_fini(orig_tail);
1056 pthread_setcancelstate(cs, 0);
1060 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1063 uint32_t h = 0, gh = 0;
1065 if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1066 if (p == RTLD_NEXT) {
1067 for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
1070 struct symdef def = find_sym(p->next, s, 0);
1071 if (!def.sym) goto failed;
1072 return def.dso->base + def.sym->st_value;
1076 sym = gnu_lookup(s, gh, p);
1079 sym = sysv_lookup(s, h, p);
1081 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1082 return p->base + sym->st_value;
1083 if (p->deps) for (i=0; p->deps[i]; i++) {
1084 if (p->deps[i]->ghashtab) {
1085 if (!gh) gh = gnu_hash(s);
1086 sym = gnu_lookup(s, gh, p->deps[i]);
1088 if (!h) h = sysv_hash(s);
1089 sym = sysv_lookup(s, h, p->deps[i]);
1091 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1092 return p->deps[i]->base + sym->st_value;
1096 snprintf(errbuf, sizeof errbuf, "Symbol not found: %s", s);
1100 int __dladdr(void *addr, Dl_info *info)
1110 pthread_rwlock_rdlock(&lock);
1111 for (p=head; p && (unsigned char *)addr-p->map>p->map_len; p=p->next);
1112 pthread_rwlock_unlock(&lock);
1117 strings = p->strings;
1119 nsym = p->hashtab[1];
1123 buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
1124 sym += p->ghashtab[1];
1125 for (i = 0; i < p->ghashtab[0]; i++) {
1126 if (buckets[i] > nsym)
1130 nsym -= p->ghashtab[1];
1131 hashval = buckets + p->ghashtab[0] + nsym;
1133 while (!(*hashval++ & 1));
1137 for (; nsym; nsym--, sym++) {
1138 if (sym->st_shndx && sym->st_value
1139 && (1<<(sym->st_info&0xf) & OK_TYPES)
1140 && (1<<(sym->st_info>>4) & OK_BINDS)) {
1141 void *symaddr = p->base + sym->st_value;
1142 if (symaddr > addr || symaddr < best)
1145 bestname = strings + sym->st_name;
1146 if (addr == symaddr)
1151 if (!best) return 0;
1153 info->dli_fname = p->name;
1154 info->dli_fbase = p->base;
1155 info->dli_sname = bestname;
1156 info->dli_saddr = best;
1161 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1164 pthread_rwlock_rdlock(&lock);
1165 res = do_dlsym(p, s, ra);
1166 pthread_rwlock_unlock(&lock);
1170 void *dlopen(const char *file, int mode)
1174 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1178 int __dladdr (void *addr, Dl_info *info)
1186 if (!errflag) return 0;
1191 int dlclose(void *p)