18 #include "pthread_impl.h"
22 static char errbuf[128];
26 #if ULONG_MAX == 0xffffffff
27 typedef Elf32_Ehdr Ehdr;
28 typedef Elf32_Phdr Phdr;
29 typedef Elf32_Sym Sym;
30 #define R_TYPE(x) ((x)&255)
31 #define R_SYM(x) ((x)>>8)
33 typedef Elf64_Ehdr Ehdr;
34 typedef Elf64_Phdr Phdr;
35 typedef Elf64_Sym Sym;
36 #define R_TYPE(x) ((x)&0xffffffff)
37 #define R_SYM(x) ((x)>>32)
40 #define MAXP2(a,b) (-(-(a)&-(b)))
41 #define ALIGN(x,y) ((x)+(y)-1 & -(y))
55 struct dso *next, *prev;
74 struct dso **deps, *needed_by;
75 char *rpath_orig, *rpath;
77 size_t tls_len, tls_size, tls_align, tls_id, tls_offset;
78 size_t relro_start, relro_end;
80 unsigned char *new_tls;
81 int new_dtv_idx, new_tls_idx;
82 struct dso *fini_next;
94 void __init_ssp(size_t *);
95 int __init_tp(void *);
96 void __init_libc(char **, char *);
98 const char *__libc_get_version(void);
100 static struct dso *head, *tail, *ldso, *fini_head;
101 static char *env_path, *sys_path;
102 static unsigned long long gencnt;
106 static int ldso_fail;
108 static jmp_buf *rtld_fail;
109 static pthread_rwlock_t lock;
110 static struct debug debug;
111 static size_t tls_cnt, tls_offset, tls_align = 4*sizeof(size_t);
112 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
113 static long long builtin_tls[(sizeof(struct pthread) + 64)/sizeof(long long)];
115 struct debug *_dl_debug_addr = &debug;
120 static void decode_vec(size_t *v, size_t *a, size_t cnt)
122 memset(a, 0, cnt*sizeof(size_t));
123 for (; v[0]; v+=2) if (v[0]<cnt) {
129 static int search_vec(size_t *v, size_t *r, size_t key)
131 for (; v[0]!=key; v+=2)
137 static uint32_t sysv_hash(const char *s0)
139 const unsigned char *s = (void *)s0;
145 return h & 0xfffffff;
148 static uint32_t gnu_hash(const char *s0)
150 const unsigned char *s = (void *)s0;
151 uint_fast32_t h = 5381;
157 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
160 Sym *syms = dso->syms;
161 uint32_t *hashtab = dso->hashtab;
162 char *strings = dso->strings;
163 for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
164 if ((!dso->versym || dso->versym[i] >= 0)
165 && (!strcmp(s, strings+syms[i].st_name)))
171 static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso)
173 Sym *syms = dso->syms;
174 char *strings = dso->strings;
175 uint32_t *hashtab = dso->ghashtab;
176 uint32_t nbuckets = hashtab[0];
177 uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
180 uint32_t i = buckets[h1 % nbuckets];
184 hashval = buckets + nbuckets + (i - hashtab[1]);
186 for (h1 |= 1; ; i++) {
188 if ((!dso->versym || dso->versym[i] >= 0)
189 && (h1 == (h2|1)) && !strcmp(s, strings + syms[i].st_name))
197 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
198 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
200 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
202 uint32_t h = 0, gh = 0;
203 struct symdef def = {0};
206 if (gh == 0x1f4039c9 && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
209 if (h == 0x595a4cc && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
211 for (; dso; dso=dso->next) {
213 if (!dso->global) continue;
215 if (!gh) gh = gnu_hash(s);
216 sym = gnu_lookup(s, gh, dso);
218 if (!h) h = sysv_hash(s);
219 sym = sysv_lookup(s, h, dso);
223 if (need_def || (sym->st_info&0xf) == STT_TLS)
226 if ((sym->st_info&0xf) != STT_TLS)
228 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
229 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
231 if (def.sym && sym->st_info>>4 == STB_WEAK) continue;
234 if (sym->st_info>>4 == STB_GLOBAL) break;
239 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
241 unsigned char *base = dso->base;
242 Sym *syms = dso->syms;
243 char *strings = dso->strings;
251 for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
252 type = R_TYPE(rel[1]);
253 sym_index = R_SYM(rel[1]);
255 sym = syms + sym_index;
256 name = strings + sym->st_name;
257 ctx = IS_COPY(type) ? head->next : head;
258 def = find_sym(ctx, name, IS_PLT(type));
259 if (!def.sym && (sym->st_shndx != SHN_UNDEF
260 || sym->st_info>>4 != STB_WEAK)) {
261 snprintf(errbuf, sizeof errbuf,
262 "Error relocating %s: %s: symbol not found",
264 if (runtime) longjmp(*rtld_fail, 1);
265 dprintf(2, "%s\n", errbuf);
274 do_single_reloc(dso, base, (void *)(base + rel[0]), type,
275 stride>2 ? rel[2] : 0, sym, sym?sym->st_size:0, def,
276 def.sym?(size_t)(def.dso->base+def.sym->st_value):0);
280 /* A huge hack: to make up for the wastefulness of shared libraries
281 * needing at least a page of dirty memory even if they have no global
282 * data, we reclaim the gaps at the beginning and end of writable maps
283 * and "donate" them to the heap by setting up minimal malloc
284 * structures and then freeing them. */
286 static void reclaim(struct dso *dso, size_t start, size_t end)
289 if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
290 if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
291 start = start + 6*sizeof(size_t)-1 & -4*sizeof(size_t);
292 end = (end & -4*sizeof(size_t)) - 2*sizeof(size_t);
293 if (start>end || end-start < 4*sizeof(size_t)) return;
294 a = (size_t *)(dso->base + start);
295 z = (size_t *)(dso->base + end);
297 a[-1] = z[0] = end-start + 2*sizeof(size_t) | 1;
302 static void reclaim_gaps(struct dso *dso)
304 Phdr *ph = dso->phdr;
305 size_t phcnt = dso->phnum;
307 for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
308 if (ph->p_type!=PT_LOAD) continue;
309 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
310 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
311 reclaim(dso, ph->p_vaddr+ph->p_memsz,
312 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
316 static void *map_library(int fd, struct dso *dso)
318 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
319 void *allocated_buf=0;
321 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
322 size_t this_min, this_max;
327 unsigned char *map=MAP_FAILED, *base;
332 ssize_t l = read(fd, buf, sizeof buf);
335 if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
337 phsize = eh->e_phentsize * eh->e_phnum;
338 if (phsize > sizeof buf - sizeof *eh) {
339 allocated_buf = malloc(phsize);
340 if (!allocated_buf) return 0;
341 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
342 if (l < 0) goto error;
343 if (l != phsize) goto noexec;
344 ph = ph0 = allocated_buf;
345 } else if (eh->e_phoff + phsize > l) {
346 l = pread(fd, buf+1, phsize, eh->e_phoff);
347 if (l < 0) goto error;
348 if (l != phsize) goto noexec;
349 ph = ph0 = (void *)(buf + 1);
351 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
353 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
354 if (ph->p_type == PT_DYNAMIC) {
356 } else if (ph->p_type == PT_TLS) {
357 tls_image = ph->p_vaddr;
358 dso->tls_align = ph->p_align;
359 dso->tls_len = ph->p_filesz;
360 dso->tls_size = ph->p_memsz;
361 } else if (ph->p_type == PT_GNU_RELRO) {
362 dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
363 dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
365 if (ph->p_type != PT_LOAD) continue;
366 if (ph->p_vaddr < addr_min) {
367 addr_min = ph->p_vaddr;
368 off_start = ph->p_offset;
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));
373 if (ph->p_vaddr+ph->p_memsz > addr_max) {
374 addr_max = ph->p_vaddr+ph->p_memsz;
377 if (!dyn) goto noexec;
378 addr_max += PAGE_SIZE-1;
379 addr_max &= -PAGE_SIZE;
380 addr_min &= -PAGE_SIZE;
381 off_start &= -PAGE_SIZE;
382 map_len = addr_max - addr_min + off_start;
383 /* The first time, we map too much, possibly even more than
384 * the length of the file. This is okay because we will not
385 * use the invalid part; we just need to reserve the right
386 * amount of virtual address space to map over later. */
387 map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start);
388 if (map==MAP_FAILED) goto error;
389 /* If the loaded file is not relocatable and the requested address is
390 * not available, then the load operation must fail. */
391 if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
395 base = map - addr_min;
398 for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
399 if (ph->p_type != PT_LOAD) continue;
400 /* Check if the programs headers are in this load segment, and
401 * if so, record the address for use by dl_iterate_phdr. */
402 if (!dso->phdr && eh->e_phoff >= ph->p_offset
403 && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
404 dso->phdr = (void *)(base + ph->p_vaddr
405 + (eh->e_phoff-ph->p_offset));
406 dso->phnum = eh->e_phnum;
407 dso->phentsize = eh->e_phentsize;
409 /* Reuse the existing mapping for the lowest-address LOAD */
410 if ((ph->p_vaddr & -PAGE_SIZE) == addr_min) continue;
411 this_min = ph->p_vaddr & -PAGE_SIZE;
412 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
413 off_start = ph->p_offset & -PAGE_SIZE;
414 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
415 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
416 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
417 if (mmap(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
419 if (ph->p_memsz > ph->p_filesz) {
420 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
421 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
422 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
423 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)
427 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
428 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
429 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC) < 0)
434 dso->map_len = map_len;
436 dso->dynv = (void *)(base+dyn);
437 if (dso->tls_size) dso->tls_image = (void *)(base+tls_image);
438 if (!runtime) reclaim_gaps(dso);
444 if (map!=MAP_FAILED) munmap(map, map_len);
449 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
454 s += strspn(s, ":\n");
455 l = strcspn(s, ":\n");
456 if (l-1 >= INT_MAX) return -1;
457 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) >= buf_size)
459 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
464 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
467 const char *s, *t, *origin;
469 if (p->rpath) return 0;
470 if (!p->rpath_orig) return -1;
471 if (!strchr(p->rpath_orig, '$')) {
472 p->rpath = p->rpath_orig;
477 while ((t=strchr(s, '$'))) {
478 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
483 if (n > SSIZE_MAX/PATH_MAX) return -1;
485 if (p->kernel_mapped) {
486 /* $ORIGIN searches cannot be performed for the main program
487 * when it is suid/sgid/AT_SECURE. This is because the
488 * pathname is under the control of the caller of execve.
489 * For libraries, however, $ORIGIN can be processed safely
490 * since the library's pathname came from a trusted source
491 * (either system paths or a call to dlopen). */
494 l = readlink("/proc/self/exe", buf, buf_size);
502 t = strrchr(origin, '/');
503 l = t ? t-origin : 0;
504 p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
505 if (!p->rpath) return -1;
509 while ((t=strchr(s, '$'))) {
512 memcpy(d, origin, l);
514 /* It was determined previously that the '$' is followed
515 * either by "ORIGIN" or "{ORIGIN}". */
516 s = t + 7 + 2*(t[1]=='{');
522 static void decode_dyn(struct dso *p)
524 size_t dyn[DYN_CNT] = {0};
525 decode_vec(p->dynv, dyn, DYN_CNT);
526 p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
527 p->strings = (void *)(p->base + dyn[DT_STRTAB]);
528 if (dyn[0]&(1<<DT_HASH))
529 p->hashtab = (void *)(p->base + dyn[DT_HASH]);
530 if (dyn[0]&(1<<DT_RPATH))
531 p->rpath_orig = (void *)(p->strings + dyn[DT_RPATH]);
532 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
533 p->ghashtab = (void *)(p->base + *dyn);
534 if (search_vec(p->dynv, dyn, DT_VERSYM))
535 p->versym = (void *)(p->base + *dyn);
538 static struct dso *load_library(const char *name, struct dso *needed_by)
540 char buf[2*NAME_MAX+2];
541 const char *pathname;
543 struct dso *p, temp_dso = {0};
550 /* Catch and block attempts to reload the implementation itself */
551 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
552 static const char *rp, reserved[] =
553 "c\0pthread\0rt\0m\0dl\0util\0xnet\0";
554 char *z = strchr(name, '.');
557 for (rp=reserved; *rp && strncmp(name+3, rp, l-3); rp+=strlen(rp)+1);
560 /* Track which names have been resolved
561 * and only report each one once. */
562 static unsigned reported;
563 unsigned mask = 1U<<(rp-reserved);
564 if (!(reported & mask)) {
566 dprintf(1, "\t%s => %s (%p)\n",
575 if (!strcmp(name, ldso->name)) is_self = 1;
580 tail = ldso->next ? ldso->next : ldso;
584 if (strchr(name, '/')) {
586 fd = open(name, O_RDONLY|O_CLOEXEC);
588 /* Search for the name to see if it's already loaded */
589 for (p=head->next; p; p=p->next) {
590 if (p->shortname && !strcmp(p->shortname, name)) {
595 if (strlen(name) > NAME_MAX) return 0;
597 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
598 for (p=needed_by; fd < 0 && p; p=p->needed_by)
599 if (!fixup_rpath(p, buf, sizeof buf))
600 fd = path_open(name, p->rpath, buf, sizeof buf);
605 if (ldso->name[0]=='/') {
607 for (s=t=z=ldso->name; *s; s++)
608 if (*s=='/') z=t, t=s;
609 prefix_len = z-ldso->name;
610 if (prefix_len < PATH_MAX)
617 char etc_ldso_path[prefix_len + 1
618 + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
619 snprintf(etc_ldso_path, sizeof etc_ldso_path,
620 "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
621 (int)prefix_len, prefix);
622 FILE *f = fopen(etc_ldso_path, "rbe");
624 if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
629 } else if (errno != ENOENT) {
633 if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
634 fd = path_open(name, sys_path, buf, sizeof buf);
638 if (fd < 0) return 0;
639 if (fstat(fd, &st) < 0) {
643 for (p=head->next; p; p=p->next) {
644 if (p->dev == st.st_dev && p->ino == st.st_ino) {
645 /* If this library was previously loaded with a
646 * pathname but a search found the same inode,
647 * setup its shortname so it can be found by name. */
648 if (!p->shortname && pathname != name)
649 p->shortname = strrchr(p->name, '/')+1;
655 map = noload ? 0 : map_library(fd, &temp_dso);
659 /* Allocate storage for the new DSO. When there is TLS, this
660 * storage must include a reservation for all pre-existing
661 * threads to obtain copies of both the new TLS, and an
662 * extended DTV capable of storing an additional slot for
663 * the newly-loaded DSO. */
664 alloc_size = sizeof *p + strlen(pathname) + 1;
665 if (runtime && temp_dso.tls_image) {
666 size_t per_th = temp_dso.tls_size + temp_dso.tls_align
667 + sizeof(void *) * (tls_cnt+3);
668 n_th = libc.threads_minus_1 + 1;
669 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
670 else alloc_size += n_th * per_th;
672 p = calloc(1, alloc_size);
674 munmap(map, temp_dso.map_len);
677 memcpy(p, &temp_dso, sizeof temp_dso);
682 p->needed_by = needed_by;
684 strcpy(p->name, pathname);
685 /* Add a shortname only if name arg was not an explicit pathname. */
686 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
688 if (runtime && !libc.has_thread_pointer) {
689 munmap(map, p->map_len);
694 p->tls_id = ++tls_cnt;
695 tls_align = MAXP2(tls_align, p->tls_align);
697 p->tls_offset = tls_offset + ( (tls_align-1) &
698 -(tls_offset + (uintptr_t)p->tls_image) );
699 tls_offset += p->tls_size;
701 tls_offset += p->tls_size + p->tls_align - 1;
702 tls_offset -= (tls_offset + (uintptr_t)p->tls_image)
704 p->tls_offset = tls_offset;
706 p->new_dtv = (void *)(-sizeof(size_t) &
707 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
708 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
715 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
720 static void load_deps(struct dso *p)
723 struct dso ***deps = &p->deps, **tmp, *dep;
724 for (; p; p=p->next) {
725 for (i=0; p->dynv[i]; i+=2) {
726 if (p->dynv[i] != DT_NEEDED) continue;
727 dep = load_library(p->strings + p->dynv[i+1], p);
729 snprintf(errbuf, sizeof errbuf,
730 "Error loading shared library %s: %m (needed by %s)",
731 p->strings + p->dynv[i+1], p->name);
732 if (runtime) longjmp(*rtld_fail, 1);
733 dprintf(2, "%s\n", errbuf);
738 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
739 if (!tmp) longjmp(*rtld_fail, 1);
748 static void load_preload(char *s)
753 for ( ; *s && isspace(*s); s++);
754 for (z=s; *z && !isspace(*z); z++);
762 static void make_global(struct dso *p)
764 for (; p; p=p->next) p->global = 1;
767 static void reloc_all(struct dso *p)
769 size_t dyn[DYN_CNT] = {0};
770 for (; p; p=p->next) {
771 if (p->relocated) continue;
772 decode_vec(p->dynv, dyn, DYN_CNT);
773 #ifdef NEED_ARCH_RELOCS
774 do_arch_relocs(p, head);
776 do_relocs(p, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
777 2+(dyn[DT_PLTREL]==DT_RELA));
778 do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2);
779 do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
781 if (p->relro_start != p->relro_end &&
782 mprotect(p->base+p->relro_start, p->relro_end-p->relro_start, PROT_READ) < 0) {
783 snprintf(errbuf, sizeof errbuf,
784 "Error relocating %s: RELRO protection failed",
786 if (runtime) longjmp(*rtld_fail, 1);
787 dprintf(2, "%s\n", errbuf);
795 static void kernel_mapped_dso(struct dso *p)
797 size_t min_addr = -1, max_addr = 0, cnt;
799 for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
800 if (ph->p_type == PT_DYNAMIC) {
801 p->dynv = (void *)(p->base + ph->p_vaddr);
802 } else if (ph->p_type == PT_GNU_RELRO) {
803 p->relro_start = ph->p_vaddr & -PAGE_SIZE;
804 p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
806 if (ph->p_type != PT_LOAD) continue;
807 if (ph->p_vaddr < min_addr)
808 min_addr = ph->p_vaddr;
809 if (ph->p_vaddr+ph->p_memsz > max_addr)
810 max_addr = ph->p_vaddr+ph->p_memsz;
812 min_addr &= -PAGE_SIZE;
813 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
814 p->map = p->base + min_addr;
815 p->map_len = max_addr - min_addr;
816 p->kernel_mapped = 1;
819 static void do_fini()
822 size_t dyn[DYN_CNT] = {0};
823 for (p=fini_head; p; p=p->fini_next) {
824 if (!p->constructed) continue;
825 decode_vec(p->dynv, dyn, DYN_CNT);
826 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
827 size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
828 size_t *fn = (size_t *)(p->base + dyn[DT_FINI_ARRAY])+n;
829 while (n--) ((void (*)(void))*--fn)();
831 #ifndef NO_LEGACY_INITFINI
832 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
833 ((void (*)(void))(p->base + dyn[DT_FINI]))();
838 static void do_init_fini(struct dso *p)
840 size_t dyn[DYN_CNT] = {0};
841 int need_locking = libc.threads_minus_1;
842 /* Allow recursive calls that arise when a library calls
843 * dlopen from one of its constructors, but block any
844 * other threads until all ctors have finished. */
845 if (need_locking) pthread_mutex_lock(&init_fini_lock);
846 for (; p; p=p->prev) {
847 if (p->constructed) continue;
849 decode_vec(p->dynv, dyn, DYN_CNT);
850 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
851 p->fini_next = fini_head;
854 #ifndef NO_LEGACY_INITFINI
855 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
856 ((void (*)(void))(p->base + dyn[DT_INIT]))();
858 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
859 size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
860 size_t *fn = (void *)(p->base + dyn[DT_INIT_ARRAY]);
861 while (n--) ((void (*)(void))*fn++)();
863 if (!need_locking && libc.threads_minus_1) {
865 pthread_mutex_lock(&init_fini_lock);
868 if (need_locking) pthread_mutex_unlock(&init_fini_lock);
871 void _dl_debug_state(void)
877 pthread_t self = __pthread_self();
879 for (p=head; p; p=p->next) {
880 if (!p->tls_id || !self->dtv[p->tls_id]) continue;
881 memcpy(self->dtv[p->tls_id], p->tls_image, p->tls_len);
882 memset((char *)self->dtv[p->tls_id]+p->tls_len, 0,
883 p->tls_size - p->tls_len);
884 if (p->tls_id == (size_t)self->dtv[0]) break;
888 void *__copy_tls(unsigned char *mem)
893 void **dtv = (void *)mem;
894 dtv[0] = (void *)tls_cnt;
896 td = (void *)(dtv+1);
902 mem += sizeof(void *) * (tls_cnt+1);
903 mem += -((uintptr_t)mem + sizeof(struct pthread)) & (tls_align-1);
905 mem += sizeof(struct pthread);
907 for (p=head; p; p=p->next) {
908 if (!p->tls_id) continue;
909 dtv[p->tls_id] = mem + p->tls_offset;
910 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
913 mem += libc.tls_size - sizeof(struct pthread);
914 mem -= (uintptr_t)mem & (tls_align-1);
917 for (p=head; p; p=p->next) {
918 if (!p->tls_id) continue;
919 dtv[p->tls_id] = mem - p->tls_offset;
920 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
927 void *__tls_get_addr(size_t *v)
929 pthread_t self = __pthread_self();
930 if (v[0]<=(size_t)self->dtv[0] && self->dtv[v[0]])
931 return (char *)self->dtv[v[0]]+v[1];
933 /* Block signals to make accessing new TLS async-signal-safe */
935 pthread_sigmask(SIG_BLOCK, SIGALL_SET, &set);
936 if (v[0]<=(size_t)self->dtv[0] && self->dtv[v[0]]) {
937 pthread_sigmask(SIG_SETMASK, &set, 0);
938 return (char *)self->dtv[v[0]]+v[1];
941 /* This is safe without any locks held because, if the caller
942 * is able to request the Nth entry of the DTV, the DSO list
943 * must be valid at least that far out and it was synchronized
944 * at program startup or by an already-completed call to dlopen. */
946 for (p=head; p->tls_id != v[0]; p=p->next);
948 /* Get new DTV space from new DSO if needed */
949 if (v[0] > (size_t)self->dtv[0]) {
950 void **newdtv = p->new_dtv +
951 (v[0]+1)*sizeof(void *)*a_fetch_add(&p->new_dtv_idx,1);
952 memcpy(newdtv, self->dtv,
953 ((size_t)self->dtv[0]+1) * sizeof(void *));
954 newdtv[0] = (void *)v[0];
958 /* Get new TLS memory from new DSO */
959 unsigned char *mem = p->new_tls +
960 (p->tls_size + p->tls_align) * a_fetch_add(&p->new_tls_idx,1);
961 mem += ((uintptr_t)p->tls_image - (uintptr_t)mem) & (p->tls_align-1);
962 self->dtv[v[0]] = mem;
963 memcpy(mem, p->tls_image, p->tls_len);
964 pthread_sigmask(SIG_SETMASK, &set, 0);
968 static void update_tls_size()
970 libc.tls_size = ALIGN(
971 (1+tls_cnt) * sizeof(void *) +
973 sizeof(struct pthread) +
978 void *__dynlink(int argc, char **argv)
980 size_t aux[AUX_CNT] = {0};
984 static struct dso builtin_dsos[3];
985 struct dso *const app = builtin_dsos+0;
986 struct dso *const lib = builtin_dsos+1;
987 struct dso *const vdso = builtin_dsos+2;
991 char **envp = argv+argc+1;
994 /* Find aux vector just past environ[] */
995 for (i=argc+1; argv[i]; i++)
996 if (!memcmp(argv[i], "LD_LIBRARY_PATH=", 16))
997 env_path = argv[i]+16;
998 else if (!memcmp(argv[i], "LD_PRELOAD=", 11))
999 env_preload = argv[i]+11;
1000 auxv = (void *)(argv+i+1);
1002 decode_vec(auxv, aux, AUX_CNT);
1004 /* Only trust user/env if kernel says we're not suid/sgid */
1005 if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1006 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]) {
1011 libc.page_size = aux[AT_PAGESZ];
1013 /* If the dynamic linker was invoked as a program itself, AT_BASE
1014 * will not be set. In that case, we assume the base address is
1015 * the start of the page containing the PHDRs; I don't know any
1016 * better approach... */
1017 if (!aux[AT_BASE]) {
1018 aux[AT_BASE] = aux[AT_PHDR] & -PAGE_SIZE;
1019 aux[AT_PHDR] = aux[AT_PHENT] = aux[AT_PHNUM] = 0;
1022 /* The dynamic linker load address is passed by the kernel
1023 * in the AUX vector, so this is easy. */
1024 lib->base = (void *)aux[AT_BASE];
1025 lib->name = lib->shortname = "libc.so";
1027 ehdr = (void *)lib->base;
1028 lib->phnum = ehdr->e_phnum;
1029 lib->phdr = (void *)(aux[AT_BASE]+ehdr->e_phoff);
1030 lib->phentsize = ehdr->e_phentsize;
1031 kernel_mapped_dso(lib);
1035 size_t interp_off = 0;
1036 size_t tls_image = 0;
1037 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1038 app->phdr = phdr = (void *)aux[AT_PHDR];
1039 app->phnum = aux[AT_PHNUM];
1040 app->phentsize = aux[AT_PHENT];
1041 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1042 if (phdr->p_type == PT_PHDR)
1043 app->base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1044 else if (phdr->p_type == PT_INTERP)
1045 interp_off = (size_t)phdr->p_vaddr;
1046 else if (phdr->p_type == PT_TLS) {
1047 tls_image = phdr->p_vaddr;
1048 app->tls_len = phdr->p_filesz;
1049 app->tls_size = phdr->p_memsz;
1050 app->tls_align = phdr->p_align;
1053 if (app->tls_size) app->tls_image = (char *)app->base + tls_image;
1054 if (interp_off) lib->name = (char *)app->base + interp_off;
1055 if ((aux[0] & (1UL<<AT_EXECFN))
1056 && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1057 app->name = (char *)aux[AT_EXECFN];
1059 app->name = argv[0];
1060 kernel_mapped_dso(app);
1063 char *ldname = argv[0];
1064 size_t l = strlen(ldname);
1065 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1066 *argv++ = (void *)-1;
1067 if (argv[0] && !strcmp(argv[0], "--")) *argv++ = (void *)-1;
1069 dprintf(2, "musl libc\n"
1071 "Dynamic Program Loader\n"
1072 "Usage: %s [--] pathname%s\n",
1073 __libc_get_version(), ldname,
1074 ldd_mode ? "" : " [args]");
1077 fd = open(argv[0], O_RDONLY);
1079 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1083 ehdr = (void *)map_library(fd, app);
1085 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1091 app->name = argv[0];
1092 aux[AT_ENTRY] = (size_t)app->base + ehdr->e_entry;
1093 /* Find the name that would have been used for the dynamic
1094 * linker had ldd not taken its place. */
1096 for (i=0; i<app->phnum; i++) {
1097 if (app->phdr[i].p_type == PT_INTERP)
1098 lib->name = (void *)(app->base
1099 + app->phdr[i].p_vaddr);
1101 dprintf(1, "\t%s (%p)\n", lib->name, lib->base);
1104 if (app->tls_size) {
1105 app->tls_id = tls_cnt = 1;
1107 app->tls_offset = 0;
1108 tls_offset = app->tls_size
1109 + ( -((uintptr_t)app->tls_image + app->tls_size)
1110 & (app->tls_align-1) );
1112 tls_offset = app->tls_offset = app->tls_size
1113 + ( -((uintptr_t)app->tls_image + app->tls_size)
1114 & (app->tls_align-1) );
1116 tls_align = MAXP2(tls_align, app->tls_align);
1121 /* Attach to vdso, if provided by the kernel */
1122 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
1123 ehdr = (void *)vdso_base;
1124 vdso->phdr = phdr = (void *)(vdso_base + ehdr->e_phoff);
1125 vdso->phnum = ehdr->e_phnum;
1126 vdso->phentsize = ehdr->e_phentsize;
1127 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1128 if (phdr->p_type == PT_DYNAMIC)
1129 vdso->dynv = (void *)(vdso_base + phdr->p_offset);
1130 if (phdr->p_type == PT_LOAD)
1131 vdso->base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1134 vdso->shortname = "linux-gate.so.1";
1141 /* Initial dso chain consists only of the app. We temporarily
1142 * append the dynamic linker/libc so we can relocate it, then
1143 * restore the initial chain in preparation for loading third
1144 * party libraries (preload/needed). */
1151 /* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */
1153 /* Donate unused parts of app and library mapping to malloc */
1157 /* Load preload/needed libraries, add their symbols to the global
1158 * namespace, and perform all remaining relocations. The main
1159 * program must be relocated LAST since it may contain copy
1160 * relocations which depend on libraries' relocations. */
1161 if (env_preload) load_preload(env_preload);
1165 #ifndef DYNAMIC_IS_RO
1166 for (i=0; app->dynv[i]; i+=2)
1167 if (app->dynv[i]==DT_DEBUG)
1168 app->dynv[i+1] = (size_t)&debug;
1171 reloc_all(app->next);
1175 if (libc.tls_size > sizeof builtin_tls) {
1176 initial_tls = calloc(libc.tls_size, 1);
1178 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1179 argv[0], libc.tls_size);
1183 initial_tls = builtin_tls;
1185 if (__init_tp(__copy_tls(initial_tls)) < 0 && tls_cnt) {
1186 dprintf(2, "%s: Thread-local storage not supported by kernel.\n", argv[0]);
1190 if (ldso_fail) _exit(127);
1191 if (ldd_mode) _exit(0);
1193 /* Switch to runtime mode: any further failures in the dynamic
1194 * linker are a reportable failure rather than a fatal startup
1195 * error. If the dynamic loader (dlopen) will not be used, free
1196 * all memory used by the dynamic linker. */
1200 debug.bp = _dl_debug_state;
1202 debug.base = lib->base;
1206 if (ssp_used) __init_ssp((void *)aux[AT_RANDOM]);
1207 __init_libc(envp, argv[0]);
1212 return (void *)aux[AT_ENTRY];
1215 void *dlopen(const char *file, int mode)
1217 struct dso *volatile p, *orig_tail, *next;
1218 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1223 if (!file) return head;
1225 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1226 pthread_rwlock_wrlock(&lock);
1230 orig_tls_cnt = tls_cnt;
1231 orig_tls_offset = tls_offset;
1232 orig_tls_align = tls_align;
1234 noload = mode & RTLD_NOLOAD;
1237 if (setjmp(*rtld_fail)) {
1238 /* Clean up anything new that was (partially) loaded */
1239 if (p && p->deps) for (i=0; p->deps[i]; i++)
1240 if (p->deps[i]->global < 0)
1241 p->deps[i]->global = 0;
1242 for (p=orig_tail->next; p; p=next) {
1244 munmap(p->map, p->map_len);
1248 tls_cnt = orig_tls_cnt;
1249 tls_offset = orig_tls_offset;
1250 tls_align = orig_tls_align;
1256 } else p = load_library(file, head);
1259 snprintf(errbuf, sizeof errbuf, noload ?
1260 "Library %s is not already loaded" :
1261 "Error loading shared library %s: %m",
1267 /* First load handling */
1270 if (p->deps) for (i=0; p->deps[i]; i++)
1271 if (!p->deps[i]->global)
1272 p->deps[i]->global = -1;
1273 if (!p->global) p->global = -1;
1275 if (p->deps) for (i=0; p->deps[i]; i++)
1276 if (p->deps[i]->global < 0)
1277 p->deps[i]->global = 0;
1278 if (p->global < 0) p->global = 0;
1281 if (mode & RTLD_GLOBAL) {
1282 if (p->deps) for (i=0; p->deps[i]; i++)
1283 p->deps[i]->global = 1;
1289 if (ssp_used) __init_ssp(libc.auxv);
1296 pthread_rwlock_unlock(&lock);
1297 if (p) do_init_fini(orig_tail);
1298 pthread_setcancelstate(cs, 0);
1302 static int invalid_dso_handle(void *h)
1305 for (p=head; p; p=p->next) if (h==p) return 0;
1306 snprintf(errbuf, sizeof errbuf, "Invalid library handle %p", (void *)h);
1311 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1314 uint32_t h = 0, gh = 0;
1316 if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1317 if (p == RTLD_DEFAULT) {
1319 } else if (p == RTLD_NEXT) {
1320 for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
1324 struct symdef def = find_sym(p, s, 0);
1325 if (!def.sym) goto failed;
1326 if ((def.sym->st_info&0xf) == STT_TLS)
1327 return __tls_get_addr((size_t []){def.dso->tls_id, def.sym->st_value});
1328 return def.dso->base + def.sym->st_value;
1330 if (p != RTLD_DEFAULT && p != RTLD_NEXT && invalid_dso_handle(p))
1334 sym = gnu_lookup(s, gh, p);
1337 sym = sysv_lookup(s, h, p);
1339 if (sym && (sym->st_info&0xf) == STT_TLS)
1340 return __tls_get_addr((size_t []){p->tls_id, sym->st_value});
1341 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1342 return p->base + sym->st_value;
1343 if (p->deps) for (i=0; p->deps[i]; i++) {
1344 if (p->deps[i]->ghashtab) {
1345 if (!gh) gh = gnu_hash(s);
1346 sym = gnu_lookup(s, gh, p->deps[i]);
1348 if (!h) h = sysv_hash(s);
1349 sym = sysv_lookup(s, h, p->deps[i]);
1351 if (sym && (sym->st_info&0xf) == STT_TLS)
1352 return __tls_get_addr((size_t []){p->deps[i]->tls_id, sym->st_value});
1353 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1354 return p->deps[i]->base + sym->st_value;
1358 snprintf(errbuf, sizeof errbuf, "Symbol not found: %s", s);
1362 int __dladdr(const void *addr, Dl_info *info)
1372 pthread_rwlock_rdlock(&lock);
1373 for (p=head; p && (unsigned char *)addr-p->map>p->map_len; p=p->next);
1374 pthread_rwlock_unlock(&lock);
1379 strings = p->strings;
1381 nsym = p->hashtab[1];
1385 buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
1386 sym += p->ghashtab[1];
1387 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
1388 if (buckets[i] > nsym)
1392 nsym -= p->ghashtab[1];
1393 hashval = buckets + p->ghashtab[0] + nsym;
1395 while (!(*hashval++ & 1));
1399 for (; nsym; nsym--, sym++) {
1401 && (1<<(sym->st_info&0xf) & OK_TYPES)
1402 && (1<<(sym->st_info>>4) & OK_BINDS)) {
1403 void *symaddr = p->base + sym->st_value;
1404 if (symaddr > addr || symaddr < best)
1407 bestname = strings + sym->st_name;
1408 if (addr == symaddr)
1413 if (!best) return 0;
1415 info->dli_fname = p->name;
1416 info->dli_fbase = p->base;
1417 info->dli_sname = bestname;
1418 info->dli_saddr = best;
1423 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1426 pthread_rwlock_rdlock(&lock);
1427 res = do_dlsym(p, s, ra);
1428 pthread_rwlock_unlock(&lock);
1432 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
1434 struct dso *current;
1435 struct dl_phdr_info info;
1437 for(current = head; current;) {
1438 info.dlpi_addr = (uintptr_t)current->base;
1439 info.dlpi_name = current->name;
1440 info.dlpi_phdr = current->phdr;
1441 info.dlpi_phnum = current->phnum;
1442 info.dlpi_adds = gencnt;
1444 info.dlpi_tls_modid = current->tls_id;
1445 info.dlpi_tls_data = current->tls_image;
1447 ret = (callback)(&info, sizeof (info), data);
1449 if (ret != 0) break;
1451 pthread_rwlock_rdlock(&lock);
1452 current = current->next;
1453 pthread_rwlock_unlock(&lock);
1458 static int invalid_dso_handle(void *h)
1460 snprintf(errbuf, sizeof errbuf, "Invalid library handle %p", (void *)h);
1464 void *dlopen(const char *file, int mode)
1468 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1472 int __dladdr (const void *addr, Dl_info *info)
1478 int __dlinfo(void *dso, int req, void *res)
1480 if (invalid_dso_handle(dso)) return -1;
1481 if (req != RTLD_DI_LINKMAP) {
1482 snprintf(errbuf, sizeof errbuf, "Unsupported request %d", req);
1486 *(struct link_map **)res = dso;
1492 if (!errflag) return 0;
1497 int dlclose(void *p)
1499 return invalid_dso_handle(p);